shithub: pokered

Download patch

ref: 969b43d443090da42a4d0d73129298f6b6d69d5a
parent: 6574881cdac656d23697be57ab048c90b0969949
author: dannye <33dannye@gmail.com>
date: Sat Aug 17 10:40:34 EDT 2019 

Update labels to match new audio macro names
and synchronize engine_2 and engine_3 with engine_1


--- a/audio/engine_1.asm
+++ b/audio/engine_1.asm
@@ -57,25 +57,25 @@
 .startChecks
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit BIT_ROTATE_DUTY, [hl]
+	bit BIT_ROTATE_DUTY_CYCLE, [hl]
 	jr z, .checkForExecuteMusic
-	call Audio1_ApplyDutyCycle
+	call Audio1_ApplyDutyCyclePattern
 .checkForExecuteMusic
 	ld b, 0
 	ld hl, wChannelFlags2
 	add hl, bc
 	bit BIT_EXECUTE_MUSIC, [hl]
-	jr nz, .checkForPitchBend
+	jr nz, .checkForPitchSlide
 	ld hl, wChannelFlags1
 	add hl, bc
 	bit BIT_NOISE_OR_SFX, [hl]
-	jr nz, .skipPitchBendVibrato
-.checkForPitchBend
+	jr nz, .skipPitchSlideVibrato
+.checkForPitchSlide
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit BIT_PITCH_BEND_ON, [hl]
+	bit BIT_PITCH_SLIDE_ON, [hl]
 	jr z, .checkVibratoDelay
-	jp Audio1_ApplyPitchBend
+	jp Audio1_ApplyPitchSlide
 .checkVibratoDelay
 	ld hl, wChannelVibratoDelayCounters
 	add hl, bc
@@ -83,7 +83,7 @@
 	and a ; check if delay is over
 	jr z, .checkForVibrato
 	dec [hl] ; otherwise, dec delay
-.skipPitchBendVibrato
+.skipPitchSlideVibrato
 	ret
 .checkForVibrato
 	ld hl, wChannelVibratoExtents
@@ -142,7 +142,7 @@
 	ret
 
 ; this routine executes all music commands that take up no time,
-; like tempo changes, duty changes etc. and doesn't return
+; like tempo changes, duty cycle changes etc. and doesn't return
 ; until the first note is reached
 Audio1_PlayNextNote:
 ; reload the vibrato delay counter
@@ -155,20 +155,20 @@
 
 	ld hl, wChannelFlags1
 	add hl, bc
-	res BIT_PITCH_BEND_ON, [hl]
-	res BIT_PITCH_BEND_DECREASING, [hl]
-	call Audio1_endchannel
+	res BIT_PITCH_SLIDE_ON, [hl]
+	res BIT_PITCH_SLIDE_DECREASING, [hl]
+	call Audio1_sound_ret
 	ret
 
-Audio1_endchannel:
+Audio1_sound_ret:
 	call Audio1_GetNextMusicByte
 	ld d, a
-	cp $ff ; is this command an endchannel?
-	jp nz, Audio1_callchannel ; no
+	cp $ff ; is this command a sound_ret?
+	jp nz, Audio1_sound_call ; no
 	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit BIT_CHANNEL_CALL, [hl]
+	bit BIT_SOUND_CALL, [hl]
 	jr nz, .returnFromCall
 	ld a, c
 	cp Ch4
@@ -187,15 +187,15 @@
 	ld a, $80
 	ld [rNR30], a
 .skipSfxChannel3
-	jr nz, .asm_9222
+	jr nz, .dontDisable
 	ld a, [wDisableChannelOutputWhenSfxEnds]
 	and a
-	jr z, .asm_9222
+	jr z, .dontDisable
 	xor a
 	ld [wDisableChannelOutputWhenSfxEnds], a
 	jr .disableChannelOutput
-.asm_9222
-	jr .asm_9248
+.dontDisable
+	jr .afterDisable
 .returnFromCall
 	res 1, [hl]
 	ld d, $0
@@ -215,7 +215,7 @@
 	inc de
 	ld a, [de]
 	ld [hl], a ; loads channel address to return to
-	jp Audio1_endchannel
+	jp Audio1_sound_ret
 .disableChannelOutput
 	ld hl, Audio1_HWChannelDisableMasks
 	add hl, bc
@@ -222,12 +222,12 @@
 	ld a, [rNR51]
 	and [hl]
 	ld [rNR51], a
-.asm_9248
+.afterDisable
 	ld a, [wChannelSoundIDs + Ch5]
 	cp CRY_SFX_START
-	jr nc, .asm_9251
+	jr nc, .maybeCry
 	jr .skipCry
-.asm_9251
+.maybeCry
 	ld a, [wChannelSoundIDs + Ch5]
 	cp CRY_SFX_END
 	jr z, .skipCry
@@ -236,10 +236,10 @@
 .cry
 	ld a, c
 	cp Ch5
-	jr z, .asm_9265
+	jr z, .skipRewind
 	call Audio1_GoBackOneCommandIfCry
 	ret c
-.asm_9265
+.skipRewind
 	ld a, [wSavedVolume]
 	ld [rNR50], a
 	xor a
@@ -250,9 +250,9 @@
 	ld [hl], b
 	ret
 
-Audio1_callchannel:
-	cp $fd ; is this command a callchannel?
-	jp nz, Audio1_loopchannel ; no
+Audio1_sound_call:
+	cp $fd ; is this command a sound_call?
+	jp nz, Audio1_sound_loop ; no
 	call Audio1_GetNextMusicByte
 	push af
 	call Audio1_GetNextMusicByte
@@ -284,12 +284,12 @@
 	ld b, $0
 	ld hl, wChannelFlags1
 	add hl, bc
-	set BIT_CHANNEL_CALL, [hl] ; set the call flag
-	jp Audio1_endchannel
+	set BIT_SOUND_CALL, [hl] ; set the call flag
+	jp Audio1_sound_ret
 
-Audio1_loopchannel:
-	cp $fe ; is this command a loopchannel?
-	jp nz, Audio1_notetype ; no
+Audio1_sound_loop:
+	cp $fe ; is this command a sound_loop?
+	jp nz, Audio1_note_type ; no
 	call Audio1_GetNextMusicByte
 	ld e, a
 	and a
@@ -304,7 +304,7 @@
 	ld [hl], a
 	call Audio1_GetNextMusicByte ; skip pointer
 	call Audio1_GetNextMusicByte
-	jp Audio1_endchannel
+	jp Audio1_sound_ret
 .loopAgain ; inc loop count
 	inc a
 	ld [hl], a
@@ -323,12 +323,12 @@
 	pop af
 	ld [hli], a
 	ld [hl], b
-	jp Audio1_endchannel
+	jp Audio1_sound_ret
 
-Audio1_notetype:
+Audio1_note_type:
 	and $f0
-	cp $d0 ; is this command a notetype?
-	jp nz, Audio1_toggleperfectpitch ; no
+	cp $d0 ; is this command a note_type?
+	jp nz, Audio1_toggle_perfect_pitch ; no
 	ld a, d
 	and $f
 	ld b, $0
@@ -367,11 +367,11 @@
 	add hl, bc
 	ld [hl], d
 .noiseChannel
-	jp Audio1_endchannel
+	jp Audio1_sound_ret
 
-Audio1_toggleperfectpitch:
+Audio1_toggle_perfect_pitch:
 	ld a, d
-	cp $e8 ; is this command a toggleperfectpitch?
+	cp $e8 ; is this command a toggle_perfect_pitch?
 	jr nz, Audio1_vibrato ; no
 	ld b, 0
 	ld hl, wChannelFlags1
@@ -379,11 +379,11 @@
 	ld a, [hl]
 	xor $1
 	ld [hl], a ; flip bit 0 of wChannelFlags1
-	jp Audio1_endchannel
+	jp Audio1_sound_ret
 
 Audio1_vibrato:
 	cp $ea ; is this command a vibrato?
-	jr nz, Audio1_pitchbend ; no
+	jr nz, Audio1_pitch_slide ; no
 	call Audio1_GetNextMusicByte
 	ld b, 0
 	ld hl, wChannelVibratoDelayCounters
@@ -427,14 +427,14 @@
 	or d
 	ld [hl], a
 
-	jp Audio1_endchannel
+	jp Audio1_sound_ret
 
-Audio1_pitchbend:
-	cp $eb ; is this command a pitchbend?
-	jr nz, Audio1_duty ; no
+Audio1_pitch_slide:
+	cp $eb ; is this command a pitch_slide?
+	jr nz, Audio1_duty_cycle ; no
 	call Audio1_GetNextMusicByte
 	ld b, 0
-	ld hl, wChannelPitchBendLengthModifiers
+	ld hl, wChannelPitchSlideLengthModifiers
 	add hl, bc
 	ld [hl], a
 	call Audio1_GetNextMusicByte
@@ -446,22 +446,22 @@
 	and $f
 	call Audio1_CalculateFrequency
 	ld b, 0
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
 	ld [hl], d
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
 	ld [hl], e
 	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	set BIT_PITCH_BEND_ON, [hl]
+	set BIT_PITCH_SLIDE_ON, [hl]
 	call Audio1_GetNextMusicByte
 	ld d, a
-	jp Audio1_notelength
+	jp Audio1_note_length
 
-Audio1_duty:
-	cp $ec ; is this command a duty?
+Audio1_duty_cycle:
+	cp $ec ; is this command a duty_cycle?
 	jr nz, Audio1_tempo ; no
 	call Audio1_GetNextMusicByte
 	rrca
@@ -468,14 +468,14 @@
 	rrca
 	and $c0
 	ld b, 0
-	ld hl, wChannelDuties
+	ld hl, wChannelDutyCycles
 	add hl, bc
-	ld [hl], a ; store duty
-	jp Audio1_endchannel
+	ld [hl], a ; store duty cycle
+	jp Audio1_sound_ret
 
 Audio1_tempo:
 	cp $ed ; is this command a tempo?
-	jr nz, Audio1_stereopanning ; no
+	jr nz, Audio1_stereo_panning ; no
 	ld a, c
 	cp Ch5
 	jr nc, .sfxChannel
@@ -500,19 +500,19 @@
 	ld [wChannelNoteDelayCountersFractionalPart + 6], a
 	ld [wChannelNoteDelayCountersFractionalPart + 7], a
 .musicChannelDone
-	jp Audio1_endchannel
+	jp Audio1_sound_ret
 
-Audio1_stereopanning:
-	cp $ee ; is this command a stereopanning?
+Audio1_stereo_panning:
+	cp $ee ; is this command a stereo_panning?
 	jr nz, Audio1_unknownmusic0xef ; no
 	call Audio1_GetNextMusicByte
 	ld [wStereoPanning], a ; store panning
-	jp Audio1_endchannel
+	jp Audio1_sound_ret
 
 ; this appears to never be used
 Audio1_unknownmusic0xef:
 	cp $ef ; is this command an unknownmusic0xef?
-	jr nz, Audio1_dutycycle ; no
+	jr nz, Audio1_duty_cycle_pattern ; no
 	call Audio1_GetNextMusicByte
 	push bc
 	call Audio1_PlaySound
@@ -525,45 +525,45 @@
 	xor a
 	ld [wChannelSoundIDs + Ch8], a
 .skip
-	jp Audio1_endchannel
+	jp Audio1_sound_ret
 
-Audio1_dutycycle:
-	cp $fc ; is this command a dutycycle?
+Audio1_duty_cycle_pattern:
+	cp $fc ; is this command a duty_cycle_pattern?
 	jr nz, Audio1_volume ; no
 	call Audio1_GetNextMusicByte
 	ld b, 0
+	ld hl, wChannelDutyCyclePatterns
+	add hl, bc
+	ld [hl], a ; store full pattern
+	and %11000000
 	ld hl, wChannelDutyCycles
 	add hl, bc
-	ld [hl], a ; store full cycle
-	and $c0
-	ld hl, wChannelDuties
-	add hl, bc
-	ld [hl], a ; store first duty
+	ld [hl], a ; store first duty cycle
 	ld hl, wChannelFlags1
 	add hl, bc
-	set BIT_ROTATE_DUTY, [hl]
-	jp Audio1_endchannel
+	set BIT_ROTATE_DUTY_CYCLE, [hl]
+	jp Audio1_sound_ret
 
 Audio1_volume:
 	cp $f0 ; is this command a volume?
-	jr nz, Audio1_executemusic ; no
+	jr nz, Audio1_execute_music ; no
 	call Audio1_GetNextMusicByte
 	ld [rNR50], a ; store volume
-	jp Audio1_endchannel
+	jp Audio1_sound_ret
 
-Audio1_executemusic:
-	cp $f8 ; is this command an executemusic?
+Audio1_execute_music:
+	cp $f8 ; is this command an execute_music?
 	jr nz, Audio1_octave ; no
 	ld b, $0
 	ld hl, wChannelFlags2
 	add hl, bc
 	set BIT_EXECUTE_MUSIC, [hl]
-	jp Audio1_endchannel
+	jp Audio1_sound_ret
 
 Audio1_octave:
 	and $f0
 	cp $e0 ; is this command an octave?
-	jr nz, Audio1_sfxnote ; no
+	jr nz, Audio1_sfx_note ; no
 	ld hl, wChannelOctaves
 	ld b, 0
 	add hl, bc
@@ -570,27 +570,27 @@
 	ld a, d
 	and $f
 	ld [hl], a ; store low nibble as octave
-	jp Audio1_endchannel
+	jp Audio1_sound_ret
 
-; sfxnote is either squarenote or noisenote depending on the channel
-Audio1_sfxnote:
-	cp $20 ; is this command a sfxnote?
-	jr nz, Audio1_pitchenvelope
+; sfx_note is either square_note or noise_note depending on the channel
+Audio1_sfx_note:
+	cp $20 ; is this command a sfx_note?
+	jr nz, Audio1_pitch_sweep
 	ld a, c
 	cp Ch4 ; is this a noise or sfx channel?
-	jr c, Audio1_pitchenvelope ; no
+	jr c, Audio1_pitch_sweep ; no
 	ld b, 0
 	ld hl, wChannelFlags2
 	add hl, bc
-	bit BIT_EXECUTE_MUSIC, [hl] ; is executemusic being used?
-	jr nz, Audio1_pitchenvelope ; yes
-	call Audio1_notelength
+	bit BIT_EXECUTE_MUSIC, [hl] ; is execute_music being used?
+	jr nz, Audio1_pitch_sweep ; yes
+	call Audio1_note_length
 
-; This code seems to do the same thing as what Audio1_ApplyDutyAndSoundLength
+; This code seems to do the same thing as what Audio1_ApplyDutyCycleAndSoundLength
 ; does below.
 	ld d, a
 	ld b, 0
-	ld hl, wChannelDuties
+	ld hl, wChannelDutyCycles
 	add hl, bc
 	ld a, [hl]
 	or d
@@ -619,18 +619,18 @@
 .skip
 	ld d, a
 	push de
-	call Audio1_ApplyDutyAndSoundLength
+	call Audio1_ApplyDutyCycleAndSoundLength
 	call Audio1_EnableChannelOutput
 	pop de
 	call Audio1_ApplyWavePatternAndFrequency
 	ret
 
-Audio1_pitchenvelope:
+Audio1_pitch_sweep:
 	ld a, c
 	cp Ch5
 	jr c, Audio1_note ; if not a sfx
 	ld a, d
-	cp $10 ; is this command a pitchenvelope?
+	cp $10 ; is this command a pitch_sweep?
 	jr nz, Audio1_note ; no
 	ld b, $0
 	ld hl, wChannelFlags2
@@ -639,17 +639,27 @@
 	jr nz, Audio1_note ; no
 	call Audio1_GetNextMusicByte
 	ld [rNR10], a
-	jp Audio1_endchannel
+	jp Audio1_sound_ret
 
 Audio1_note:
 	ld a, c
 	cp Ch4
-	jr nz, Audio1_notelength ; if not noise channel
+	jr nz, Audio1_note_length ; if not noise channel
 	ld a, d
 	and $f0
 	cp $b0 ; is this command a dnote?
-	jr z, Audio1_dnote
-	jr nc, Audio1_notelength ; no
+	jr z, .dnote
+	jr nc, Audio1_note_length ; no
+
+	; this executes when on the noise channel and
+	; the command id is less than $b0
+	; in this case, the upper nybble is used as the noise instrument ($1-$a)
+	; and the lower nybble is the length minus 1 (0-15)
+	; however, this doesn't work for instrument #2 because the command id
+	; is captured by the noise_note command (command id $2x)
+	; this essentially acts like a dnote command that is only 1 byte
+	; instead of 2 and can only be used with instruments 1 and 3 through 10
+	; this is unused by the game
 	swap a
 	ld b, a
 	ld a, d
@@ -658,26 +668,26 @@
 	ld a, b
 	push de
 	push bc
-	jr asm_94fd
+	jr .playDnote
 
-Audio1_dnote:
+.dnote
 	ld a, d
 	and $f
 	push af
 	push bc
 	call Audio1_GetNextMusicByte ; get dnote instrument
-asm_94fd
+.playDnote
 	ld d, a
 	ld a, [wDisableChannelOutputWhenSfxEnds]
 	and a
-	jr nz, .asm_9508
+	jr nz, .skipDnote
 	ld a, d
 	call Audio1_PlaySound
-.asm_9508
+.skipDnote
 	pop bc
 	pop de
 
-Audio1_notelength:
+Audio1_note_length:
 	ld a, d
 	push af
 	and $f
@@ -727,15 +737,15 @@
 	ld hl, wChannelFlags2
 	add hl, bc
 	bit BIT_EXECUTE_MUSIC, [hl]
-	jr nz, Audio1_notepitch
+	jr nz, Audio1_note_pitch
 	ld hl, wChannelFlags1
 	add hl, bc
 	bit BIT_NOISE_OR_SFX, [hl]
-	jr z, Audio1_notepitch
+	jr z, Audio1_note_pitch
 	pop hl
 	ret
 
-Audio1_notepitch:
+Audio1_note_pitch:
 	pop af
 	and $f0
 	cp $c0 ; compare to rest
@@ -784,10 +794,10 @@
 	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit BIT_PITCH_BEND_ON, [hl]
-	jr z, .skipPitchBend
-	call Audio1_InitPitchBendVars
-.skipPitchBend
+	bit BIT_PITCH_SLIDE_ON, [hl]
+	jr z, .skipPitchSlide
+	call Audio1_InitPitchSlideVars
+.skipPitchSlide
 	push de
 	ld a, c
 	cp Ch5
@@ -812,13 +822,13 @@
 	ld b, REG_VOLUME_ENVELOPE
 	call Audio1_GetRegisterPointer
 	ld [hl], d
-	call Audio1_ApplyDutyAndSoundLength
+	call Audio1_ApplyDutyCycleAndSoundLength
 	call Audio1_EnableChannelOutput
 	pop de
 	ld b, $0
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit BIT_PERFECT_PITCH, [hl] ; has toggleperfectpitch been used?
+	bit BIT_PERFECT_PITCH, [hl] ; has toggle_perfect_pitch been used?
 	jr z, .skipFrequencyInc
 	inc e                       ; if yes, increment the frequency by 1
 	jr nc, .skipFrequencyInc
@@ -867,7 +877,7 @@
 	ld [rNR51], a
 	ret
 
-Audio1_ApplyDutyAndSoundLength:
+Audio1_ApplyDutyCycleAndSoundLength:
 	ld b, 0
 	ld hl, wChannelNoteDelayCounters ; use the note delay as sound length
 	add hl, bc
@@ -877,11 +887,11 @@
 	jr z, .skipDuty ; if music channel 3
 	cp Ch7
 	jr z, .skipDuty ; if sfx channel 3
-; include duty (except on channel 3 which doesn't have it)
+; include duty cycle (except on channel 3 which doesn't have it)
 	ld a, d
 	and $3f
 	ld d, a
-	ld hl, wChannelDuties
+	ld hl, wChannelDutyCycles
 	add hl, bc
 	ld a, [hl]
 	or d
@@ -1022,19 +1032,19 @@
 	scf
 	ret
 
-Audio1_ApplyPitchBend:
+Audio1_ApplyPitchSlide:
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit BIT_PITCH_BEND_DECREASING, [hl]
+	bit BIT_PITCH_SLIDE_DECREASING, [hl]
 	jp nz, .frequencyDecreasing
 ; frequency increasing
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld e, [hl]
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld d, [hl]
-	ld hl, wChannelPitchBendFrequencySteps
+	ld hl, wChannelPitchSlideFrequencySteps
 	add hl, bc
 	ld l, [hl]
 	ld h, b
@@ -1041,10 +1051,10 @@
 	add hl, de
 	ld d, h
 	ld e, l
-	ld hl, wChannelPitchBendCurrentFrequencyFractionalPart
+	ld hl, wChannelPitchSlideCurrentFrequencyFractionalPart
 	add hl, bc
 	push hl
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
 	add hl, bc
 	ld a, [hl]
 	pop hl
@@ -1056,13 +1066,13 @@
 	ld a, 0
 	adc d
 	ld d, a
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
 	ld a, [hl]
 	cp d
 	jp c, .reachedTargetFrequency
 	jr nz, .applyUpdatedFrequency
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
 	ld a, [hl]
 	cp e
@@ -1069,13 +1079,13 @@
 	jp c, .reachedTargetFrequency
 	jr .applyUpdatedFrequency
 .frequencyDecreasing
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld a, [hl]
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld d, [hl]
-	ld hl, wChannelPitchBendFrequencySteps
+	ld hl, wChannelPitchSlideFrequencySteps
 	add hl, bc
 	ld e, [hl]
 	sub e
@@ -1083,7 +1093,7 @@
 	ld a, d
 	sbc b
 	ld d, a
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
 	add hl, bc
 	ld a, [hl]
 	add a
@@ -1094,22 +1104,22 @@
 	ld a, d
 	sbc b
 	ld d, a
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
 	ld a, d
 	cp [hl]
 	jr c, .reachedTargetFrequency
 	jr nz, .applyUpdatedFrequency
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
 	ld a, e
 	cp [hl]
 	jr c, .reachedTargetFrequency
 .applyUpdatedFrequency
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld [hl], e
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld [hl], d
 	ld b, REG_FREQUENCY_LO
@@ -1119,24 +1129,24 @@
 	ld [hl], d
 	ret
 .reachedTargetFrequency
-; Turn off pitch bend when the target frequency has been reached.
+; Turn off pitch slide when the target frequency has been reached.
 	ld hl, wChannelFlags1
 	add hl, bc
-	res BIT_PITCH_BEND_ON, [hl]
-	res BIT_PITCH_BEND_DECREASING, [hl]
+	res BIT_PITCH_SLIDE_ON, [hl]
+	res BIT_PITCH_SLIDE_DECREASING, [hl]
 	ret
 
-Audio1_InitPitchBendVars:
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+Audio1_InitPitchSlideVars:
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld [hl], d
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld [hl], e
 	ld hl, wChannelNoteDelayCounters
 	add hl, bc
 	ld a, [hl]
-	ld hl, wChannelPitchBendLengthModifiers
+	ld hl, wChannelPitchSlideLengthModifiers
 	add hl, bc
 	sub [hl]
 	jr nc, .next
@@ -1143,7 +1153,7 @@
 	ld a, 1
 .next
 	ld [hl], a
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
 	ld a, e
 	sub [hl]
@@ -1150,7 +1160,7 @@
 	ld e, a
 	ld a, d
 	sbc b
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
 	sub [hl]
 	jr c, .targetFrequencyGreater
@@ -1158,18 +1168,18 @@
 	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	set BIT_PITCH_BEND_DECREASING, [hl]
+	set BIT_PITCH_SLIDE_DECREASING, [hl]
 	jr .next2
 .targetFrequencyGreater
 ; If the target frequency is greater, subtract the current frequency from
 ; the target frequency to get the absolute difference.
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld d, [hl]
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld e, [hl]
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
 	ld a, [hl]
 	sub e
@@ -1184,7 +1194,7 @@
 	sbc b
 	ld d, a
 
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
 	ld a, [hl]
 	sub d
@@ -1192,10 +1202,10 @@
 	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	res BIT_PITCH_BEND_DECREASING, [hl]
+	res BIT_PITCH_SLIDE_DECREASING, [hl]
 
 .next2
-	ld hl, wChannelPitchBendLengthModifiers
+	ld hl, wChannelPitchSlideLengthModifiers
 	add hl, bc
 .divideLoop
 	inc b
@@ -1214,20 +1224,20 @@
 	add [hl]
 	ld d, b ; d = quotient + 1
 	ld b, 0
-	ld hl, wChannelPitchBendFrequencySteps
+	ld hl, wChannelPitchSlideFrequencySteps
 	add hl, bc
 	ld [hl], d ; store quotient + 1
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
 	add hl, bc
 	ld [hl], a ; store remainder - dividend
-	ld hl, wChannelPitchBendCurrentFrequencyFractionalPart
+	ld hl, wChannelPitchSlideCurrentFrequencyFractionalPart
 	add hl, bc
 	ld [hl], a ; store remainder - dividend
 	ret
 
-Audio1_ApplyDutyCycle:
+Audio1_ApplyDutyCyclePattern:
 	ld b, 0
-	ld hl, wChannelDutyCycles
+	ld hl, wChannelDutyCyclePatterns
 	add hl, bc
 	ld a, [hl]
 	rlca
@@ -1322,7 +1332,7 @@
 	ld [wSoundID], a
 	cp $ff
 	jp z, .stopAllAudio
-	cp MAX_SFX_ID
+	cp MAX_SFX_ID_1
 	jp z, .playSfx
 	jp c, .playSfx
 	cp $fe
@@ -1346,10 +1356,10 @@
 	call .FillMem
 	ld hl, wChannelFlags1
 	call .FillMem
-	ld hl, wChannelDuties
-	call .FillMem
 	ld hl, wChannelDutyCycles
 	call .FillMem
+	ld hl, wChannelDutyCyclePatterns
+	call .FillMem
 	ld hl, wChannelVibratoDelayCounters
 	call .FillMem
 	ld hl, wChannelVibratoExtents
@@ -1362,21 +1372,21 @@
 	call .FillMem
 	ld hl, wChannelFlags2
 	call .FillMem
-	ld hl, wChannelPitchBendLengthModifiers
+	ld hl, wChannelPitchSlideLengthModifiers
 	call .FillMem
-	ld hl, wChannelPitchBendFrequencySteps
+	ld hl, wChannelPitchSlideFrequencySteps
 	call .FillMem
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
 	call .FillMem
-	ld hl, wChannelPitchBendCurrentFrequencyFractionalPart
+	ld hl, wChannelPitchSlideCurrentFrequencyFractionalPart
 	call .FillMem
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	call .FillMem
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	call .FillMem
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	call .FillMem
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	call .FillMem
 	ld a, $1
 	ld hl, wChannelLoopCounters
@@ -1441,26 +1451,26 @@
 	add hl, de
 	ld a, [hl]
 	and a
-	jr z, .asm_99a3
+	jr z, .playChannel
 	ld a, e
-	cp $7
-	jr nz, .asm_999a
+	cp Ch8
+	jr nz, .notNoiseChannel
 	ld a, [wSoundID]
-	cp $14
-	jr nc, .asm_9993
+	cp NOISE_INSTRUMENTS_END
+	jr nc, .notNoiseInstrument
 	ret
-.asm_9993
+.notNoiseInstrument
 	ld a, [hl]
-	cp $14
-	jr z, .asm_99a3
-	jr c, .asm_99a3
-.asm_999a
+	cp NOISE_INSTRUMENTS_END
+	jr z, .playChannel
+	jr c, .playChannel
+.notNoiseChannel
 	ld a, [wSoundID]
 	cp [hl]
-	jr z, .asm_99a3
-	jr c, .asm_99a3
+	jr z, .playChannel
+	jr c, .playChannel
 	ret
-.asm_99a3
+.playChannel
 	xor a
 	push de
 	ld h, d
@@ -1483,10 +1493,10 @@
 	ld hl, wChannelFlags1
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelDuties
+	ld hl, wChannelDutyCycles
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelDutyCycles
+	ld hl, wChannelDutyCyclePatterns
 	add hl, de
 	ld [hl], a
 	ld hl, wChannelVibratoDelayCounters
@@ -1504,28 +1514,28 @@
 	ld hl, wChannelVibratoDelayCounterReloadValues
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendLengthModifiers
+	ld hl, wChannelPitchSlideLengthModifiers
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendFrequencySteps
+	ld hl, wChannelPitchSlideFrequencySteps
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendCurrentFrequencyFractionalPart
+	ld hl, wChannelPitchSlideCurrentFrequencyFractionalPart
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, de
 	ld [hl], a
 	ld hl, wChannelFlags2
@@ -1543,10 +1553,10 @@
 	ld [hl], a
 	ld a, e
 	cp Ch5
-	jr nz, .asm_9a2b
+	jr nz, .skipSweepDisable
 	ld a, $8
 	ld [rNR10], a ; sweep off
-.asm_9a2b
+.skipSweepDisable
 	ld a, c
 	and a
 	jp z, .playSoundCommon
@@ -1667,9 +1677,9 @@
 	jr nz, .commandPointerLoop
 	ld a, [wSoundID]
 	cp CRY_SFX_START
-	jr nc, .asm_9aeb
+	jr nc, .maybeCry
 	jr .done
-.asm_9aeb
+.maybeCry
 	ld a, [wSoundID]
 	cp CRY_SFX_END
 	jr z, .done
@@ -1682,10 +1692,10 @@
 	ld [hli], a
 	ld [hl], a
 	ld hl, wChannelCommandPointers + Ch7 * 2 ; sfx wave channel pointer
-	ld de, Audio1_CryEndchannel
+	ld de, Audio1_CryRet
 	ld [hl], e
 	inc hl
-	ld [hl], d ; overwrite pointer to point to endchannel
+	ld [hl], d ; overwrite pointer to point to sound_ret
 	ld a, [wSavedVolume]
 	and a
 	jr nz, .done
@@ -1696,7 +1706,7 @@
 .done
 	ret
 
-Audio1_CryEndchannel:
+Audio1_CryRet:
 	sound_ret
 
 Audio1_HWChannelBaseAddresses:
@@ -1725,5 +1735,3 @@
 	dw $FB58 ; A_
 	dw $FB9B ; A#
 	dw $FBDA ; B_
-
-
--- a/audio/engine_2.asm
+++ b/audio/engine_2.asm
@@ -1,9 +1,11 @@
 ; The second of three duplicated sound engines.
+; This copy has a few differences relating to battle sound effects
+; and the low health alarm that plays in battle
 
 Audio2_UpdateMusic::
 	ld c, Ch1
 .loop
-	ld b, $0
+	ld b, 0
 	ld hl, wChannelSoundIDs
 	add hl, bc
 	ld a, [hl]
@@ -19,7 +21,7 @@
 	jr nz, .nextChannel
 	set 7, a
 	ld [wMuteAudioAndPauseMusic], a
-	xor a
+	xor a ; disable all channels' output
 	ld [rNR51], a
 	ld [rNR30], a
 	ld a, $80
@@ -29,7 +31,7 @@
 	call Audio2_ApplyMusicAffects
 .nextChannel
 	ld a, c
-	inc c
+	inc c ; inc channel number
 	cp Ch8
 	jr nz, .loop
 	ret
@@ -36,12 +38,6 @@
 
 ; this routine checks flags for music effects currently applied
 ; to the channel and calls certain functions based on flags.
-; known flags for wChannelFlags1:
-;   0: toggleperfectpitch has been used
-;   1: call has been used
-;   3: a toggle used only by this routine for vibrato
-;   4: pitchbend flag
-;   6: dutycycle flag
 Audio2_ApplyMusicAffects:
 	ld b, $0
 	ld hl, wChannelNoteDelayCounters ; delay until next note
@@ -63,36 +59,36 @@
 .startChecks
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 6, [hl] ; dutycycle
+	bit BIT_ROTATE_DUTY_CYCLE, [hl]
 	jr z, .checkForExecuteMusic
-	call Audio2_ApplyDutyCycle
+	call Audio2_ApplyDutyCyclePattern
 .checkForExecuteMusic
-	ld b, $0
+	ld b, 0
 	ld hl, wChannelFlags2
 	add hl, bc
-	bit 0, [hl]
-	jr nz, .checkForPitchBend
+	bit BIT_EXECUTE_MUSIC, [hl]
+	jr nz, .checkForPitchSlide
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 2, [hl]
-	jr nz, .disablePitchBendVibrato
-.checkForPitchBend
+	bit BIT_NOISE_OR_SFX, [hl]
+	jr nz, .skipPitchSlideVibrato
+.checkForPitchSlide
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 4, [hl] ; pitchbend
+	bit BIT_PITCH_SLIDE_ON, [hl]
 	jr z, .checkVibratoDelay
-	jp Audio2_ApplyPitchBend
+	jp Audio2_ApplyPitchSlide
 .checkVibratoDelay
-	ld hl, wChannelVibratoDelayCounters ; vibrato delay
+	ld hl, wChannelVibratoDelayCounters
 	add hl, bc
 	ld a, [hl]
 	and a ; check if delay is over
 	jr z, .checkForVibrato
 	dec [hl] ; otherwise, dec delay
-.disablePitchBendVibrato
+.skipPitchSlideVibrato
 	ret
 .checkForVibrato
-	ld hl, wChannelVibratoExtents ; vibrato rate
+	ld hl, wChannelVibratoExtents
 	add hl, bc
 	ld a, [hl]
 	and a
@@ -105,22 +101,24 @@
 	ld a, [hl]
 	and $f
 	and a
-	jr z, .vibratoAlreadyDone
-	dec [hl] ; apply vibrato pitch change
+	jr z, .applyVibrato
+	dec [hl] ; decrement counter
 	ret
-.vibratoAlreadyDone
+.applyVibrato
 	ld a, [hl]
 	swap [hl]
 	or [hl]
-	ld [hl], a ; reset the vibrato value and start again
+	ld [hl], a ; reload the counter
 	ld hl, wChannelFrequencyLowBytes
 	add hl, bc
 	ld e, [hl] ; get note pitch
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 3, [hl] ; this is the only code that sets/resets bit three so
-	jr z, .unset ; it continuously alternates which path it takes
-	res 3, [hl]
+; This is the only code that sets/resets the vibrato direction bit, so it
+; continuously alternates which path it takes.
+	bit BIT_VIBRATO_DIRECTION, [hl]
+	jr z, .unset
+	res BIT_VIBRATO_DIRECTION, [hl]
 	ld a, d
 	and $f
 	ld d, a
@@ -127,11 +125,11 @@
 	ld a, e
 	sub d
 	jr nc, .noCarry
-	ld a, $0
+	ld a, 0
 .noCarry
 	jr .done
 .unset
-	set 3, [hl]
+	set BIT_VIBRATO_DIRECTION, [hl]
 	ld a, d
 	and $f0
 	swap a
@@ -140,15 +138,16 @@
 	ld a, $ff
 .done
 	ld d, a
-	ld b, $3
-	call Audio2_21ff7
+	ld b, REG_FREQUENCY_LO
+	call Audio2_GetRegisterPointer
 	ld [hl], d
 	ret
 
 ; this routine executes all music commands that take up no time,
-; like tempo changes, duty changes etc. and doesn't return
+; like tempo changes, duty cycle changes etc. and doesn't return
 ; until the first note is reached
 Audio2_PlayNextNote:
+; reload the vibrato delay counter
 	ld hl, wChannelVibratoDelayCounterReloadValues
 	add hl, bc
 	ld a, [hl]
@@ -155,55 +154,59 @@
 	ld hl, wChannelVibratoDelayCounters
 	add hl, bc
 	ld [hl], a
+
 	ld hl, wChannelFlags1
 	add hl, bc
-	res 4, [hl]
-	res 5, [hl]
+	res BIT_PITCH_SLIDE_ON, [hl]
+	res BIT_PITCH_SLIDE_DECREASING, [hl]
+	; --- this section is only present in this copy of the sound engine
 	ld a, c
 	cp Ch5
 	jr nz, .beginChecks
-	ld a, [wLowHealthAlarm] ;low health alarm enabled?
+	ld a, [wLowHealthAlarm] ; low health alarm enabled?
 	bit 7, a
 	ret nz
 .beginChecks
-	call Audio2_endchannel
+	; ---
+	call Audio2_sound_ret
 	ret
 
-Audio2_endchannel:
+Audio2_sound_ret:
 	call Audio2_GetNextMusicByte
 	ld d, a
-	cp $ff ; is this command an endchannel?
-	jp nz, Audio2_callchannel ; no
-	ld b, $0 ; yes
+	cp $ff ; is this command a sound_ret?
+	jp nz, Audio2_sound_call ; no
+	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 1, [hl]
+	bit BIT_SOUND_CALL, [hl]
 	jr nz, .returnFromCall
 	ld a, c
 	cp Ch4
 	jr nc, .noiseOrSfxChannel
-	jr .asm_219c0
+	jr .disableChannelOutput
 .noiseOrSfxChannel
-	res 2, [hl]
+	res BIT_NOISE_OR_SFX, [hl]
 	ld hl, wChannelFlags2
 	add hl, bc
-	res 0, [hl]
+	res BIT_EXECUTE_MUSIC, [hl]
 	cp Ch7
-	jr nz, .notSfxChannel3
+	jr nz, .skipSfxChannel3
+; restart hardware channel 3 (wave channel) output
 	ld a, $0
 	ld [rNR30], a
 	ld a, $80
 	ld [rNR30], a
-.notSfxChannel3
-	jr nz, .asm_219a3
+.skipSfxChannel3
+	jr nz, .dontDisable
 	ld a, [wDisableChannelOutputWhenSfxEnds]
 	and a
-	jr z, .asm_219a3
+	jr z, .dontDisable
 	xor a
 	ld [wDisableChannelOutputWhenSfxEnds], a
-	jr .asm_219c0
-.asm_219a3
-	jr .asm_219c9
+	jr .disableChannelOutput
+.dontDisable
+	jr .afterDisable
 .returnFromCall
 	res 1, [hl]
 	ld d, $0
@@ -223,45 +226,45 @@
 	inc de
 	ld a, [de]
 	ld [hl], a ; loads channel address to return to
-	jp Audio2_endchannel
-.asm_219c0
-	ld hl, Unknown_222de
+	jp Audio2_sound_ret
+.disableChannelOutput
+	ld hl, Audio2_HWChannelDisableMasks
 	add hl, bc
 	ld a, [rNR51]
 	and [hl]
 	ld [rNR51], a
-.asm_219c9
+.afterDisable
 	ld a, [wChannelSoundIDs + Ch5]
-	cp $14
-	jr nc, .asm_219d2
-	jr .asm_219ef
-.asm_219d2
+	cp CRY_SFX_START
+	jr nc, .maybeCry
+	jr .skipCry
+.maybeCry
 	ld a, [wChannelSoundIDs + Ch5]
-	cp $86
-	jr z, .asm_219ef
-	jr c, .asm_219dd
-	jr .asm_219ef
-.asm_219dd
+	cp CRY_SFX_END
+	jr z, .skipCry
+	jr c, .cry
+	jr .skipCry
+.cry
 	ld a, c
 	cp Ch5
-	jr z, .asm_219e6
-	call Audio2_21e6d
+	jr z, .skipRewind
+	call Audio2_GoBackOneCommandIfCry
 	ret c
-.asm_219e6
+.skipRewind
 	ld a, [wSavedVolume]
 	ld [rNR50], a
 	xor a
 	ld [wSavedVolume], a
-.asm_219ef
+.skipCry
 	ld hl, wChannelSoundIDs
 	add hl, bc
 	ld [hl], b
 	ret
 
-Audio2_callchannel:
-	cp $fd ; is this command a callchannel?
-	jp nz, Audio2_loopchannel ; no
-	call Audio2_GetNextMusicByte ; yes
+Audio2_sound_call:
+	cp $fd ; is this command a sound_call?
+	jp nz, Audio2_sound_loop ; no
+	call Audio2_GetNextMusicByte
 	push af
 	call Audio2_GetNextMusicByte
 	ld d, a
@@ -292,17 +295,17 @@
 	ld b, $0
 	ld hl, wChannelFlags1
 	add hl, bc
-	set 1, [hl] ; set the call flag
-	jp Audio2_endchannel
+	set BIT_SOUND_CALL, [hl] ; set the call flag
+	jp Audio2_sound_ret
 
-Audio2_loopchannel:
-	cp $fe ; is this command a loopchannel?
-	jp nz, Audio2_notetype ; no
-	call Audio2_GetNextMusicByte ; yes
+Audio2_sound_loop:
+	cp $fe ; is this command a sound_loop?
+	jp nz, Audio2_note_type ; no
+	call Audio2_GetNextMusicByte
 	ld e, a
 	and a
 	jr z, .infiniteLoop
-	ld b, $0
+	ld b, 0
 	ld hl, wChannelLoopCounters
 	add hl, bc
 	ld a, [hl]
@@ -312,7 +315,7 @@
 	ld [hl], a
 	call Audio2_GetNextMusicByte ; skip pointer
 	call Audio2_GetNextMusicByte
-	jp Audio2_endchannel
+	jp Audio2_sound_ret
 .loopAgain ; inc loop count
 	inc a
 	ld [hl], a
@@ -331,13 +334,13 @@
 	pop af
 	ld [hli], a
 	ld [hl], b
-	jp Audio2_endchannel
+	jp Audio2_sound_ret
 
-Audio2_notetype:
+Audio2_note_type:
 	and $f0
-	cp $d0 ; is this command a notetype?
-	jp nz, Audio2_toggleperfectpitch ; no
-	ld a, d ; yes
+	cp $d0 ; is this command a note_type?
+	jp nz, Audio2_toggle_perfect_pitch ; no
+	ld a, d
 	and $f
 	ld b, $0
 	ld hl, wChannelNoteSpeeds
@@ -352,15 +355,15 @@
 	cp Ch3
 	jr z, .musicChannel3
 	cp Ch7
-	jr nz, .notChannel3
+	jr nz, .skipChannel3
 	ld hl, wSfxWaveInstrument
-	jr .sfxChannel3
+	jr .channel3
 .musicChannel3
 	ld hl, wMusicWaveInstrument
-.sfxChannel3
+.channel3
 	ld a, d
 	and $f
-	ld [hl], a ; store low nibble of param as duty
+	ld [hl], a ; store low nibble of param as wave instrument
 	ld a, d
 	and $30
 	sla a
@@ -369,31 +372,31 @@
 
 	; if channel 3, store high nibble as volume
 	; else, store volume (high nibble) and fade (low nibble)
-.notChannel3
-	ld b, $0
+.skipChannel3
+	ld b, 0
 	ld hl, wChannelVolumes
 	add hl, bc
 	ld [hl], d
 .noiseChannel
-	jp Audio2_endchannel
+	jp Audio2_sound_ret
 
-Audio2_toggleperfectpitch:
+Audio2_toggle_perfect_pitch:
 	ld a, d
-	cp $e8 ; is this command a toggleperfectpitch?
+	cp $e8 ; is this command a toggle_perfect_pitch?
 	jr nz, Audio2_vibrato ; no
-	ld b, $0 ; yes
+	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
 	ld a, [hl]
 	xor $1
 	ld [hl], a ; flip bit 0 of wChannelFlags1
-	jp Audio2_endchannel
+	jp Audio2_sound_ret
 
 Audio2_vibrato:
 	cp $ea ; is this command a vibrato?
-	jr nz, Audio2_pitchbend ; no
-	call Audio2_GetNextMusicByte ; yes
-	ld b, $0
+	jr nz, Audio2_pitch_slide ; no
+	call Audio2_GetNextMusicByte
+	ld b, 0
 	ld hl, wChannelVibratoDelayCounters
 	add hl, bc
 	ld [hl], a ; store delay
@@ -402,9 +405,16 @@
 	ld [hl], a ; store delay
 	call Audio2_GetNextMusicByte
 	ld d, a
+
+; The high nybble of the command byte is the extent of the vibrato.
+; Let n be the extent.
+; The upper nybble of the channel's byte in the wChannelVibratoExtents
+; array will store the extent above the note: (n / 2) + (n % 2).
+; The lower nybble will store the extent below the note: (n / 2).
+; These two values add to the total extent, n.
 	and $f0
 	swap a
-	ld b, $0
+	ld b, 0
 	ld hl, wChannelVibratoExtents
 	add hl, bc
 	srl a
@@ -412,7 +422,13 @@
 	adc b
 	swap a
 	or e
-	ld [hl], a ; store rate as both high and low nibbles
+	ld [hl], a
+
+; The low nybble of the command byte is the rate of the vibrato.
+; The high and low nybbles of the channel's byte in the wChannelVibratoRates
+; array are both initialised to this value because the high nybble is the
+; counter reload value and the low nybble is the counter itself, which should
+; start at its value upon reload.
 	ld a, d
 	and $f
 	ld d, a
@@ -420,17 +436,18 @@
 	add hl, bc
 	swap a
 	or d
-	ld [hl], a ; store depth as both high and low nibbles
-	jp Audio2_endchannel
+	ld [hl], a
 
-Audio2_pitchbend:
-	cp $eb ; is this command a pitchbend?
-	jr nz, Audio2_duty ; no
-	call Audio2_GetNextMusicByte ; yes
-	ld b, $0
-	ld hl, wChannelPitchBendLengthModifiers
+	jp Audio2_sound_ret
+
+Audio2_pitch_slide:
+	cp $eb ; is this command a pitch_slide?
+	jr nz, Audio2_duty_cycle ; no
+	call Audio2_GetNextMusicByte
+	ld b, 0
+	ld hl, wChannelPitchSlideLengthModifiers
 	add hl, bc
-	ld [hl], a ; store first param
+	ld [hl], a
 	call Audio2_GetNextMusicByte
 	ld d, a
 	and $f0
@@ -438,39 +455,39 @@
 	ld b, a
 	ld a, d
 	and $f
-	call Audio2_22017
-	ld b, $0
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	call Audio2_CalculateFrequency
+	ld b, 0
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
-	ld [hl], d ; store unknown part of second param
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld [hl], d
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
-	ld [hl], e ; store unknown part of second param
-	ld b, $0
+	ld [hl], e
+	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	set 4, [hl] ; set pitchbend flag
+	set BIT_PITCH_SLIDE_ON, [hl]
 	call Audio2_GetNextMusicByte
 	ld d, a
-	jp Audio2_notelength
+	jp Audio2_note_length
 
-Audio2_duty:
-	cp $ec ; is this command a duty?
+Audio2_duty_cycle:
+	cp $ec ; is this command a duty_cycle?
 	jr nz, Audio2_tempo ; no
-	call Audio2_GetNextMusicByte ; yes
+	call Audio2_GetNextMusicByte
 	rrca
 	rrca
 	and $c0
-	ld b, $0
-	ld hl, wChannelDuties
+	ld b, 0
+	ld hl, wChannelDutyCycles
 	add hl, bc
-	ld [hl], a ; store duty
-	jp Audio2_endchannel
+	ld [hl], a ; store duty cycle
+	jp Audio2_sound_ret
 
 Audio2_tempo:
 	cp $ed ; is this command a tempo?
-	jr nz, Audio2_stereopanning ; no
-	ld a, c ; yes
+	jr nz, Audio2_stereo_panning ; no
+	ld a, c
 	cp Ch5
 	jr nc, .sfxChannel
 	call Audio2_GetNextMusicByte
@@ -494,20 +511,20 @@
 	ld [wChannelNoteDelayCountersFractionalPart + 6], a
 	ld [wChannelNoteDelayCountersFractionalPart + 7], a
 .musicChannelDone
-	jp Audio2_endchannel
+	jp Audio2_sound_ret
 
-Audio2_stereopanning:
-	cp $ee ; is this command a stereopanning?
+Audio2_stereo_panning:
+	cp $ee ; is this command a stereo_panning?
 	jr nz, Audio2_unknownmusic0xef ; no
-	call Audio2_GetNextMusicByte ; yes
+	call Audio2_GetNextMusicByte
 	ld [wStereoPanning], a ; store panning
-	jp Audio2_endchannel
+	jp Audio2_sound_ret
 
 ; this appears to never be used
 Audio2_unknownmusic0xef:
 	cp $ef ; is this command an unknownmusic0xef?
-	jr nz, Audio2_dutycycle ; no
-	call Audio2_GetNextMusicByte ; yes
+	jr nz, Audio2_duty_cycle_pattern ; no
+	call Audio2_GetNextMusicByte
 	push bc
 	call Audio2_PlaySound
 	pop bc
@@ -519,124 +536,141 @@
 	xor a
 	ld [wChannelSoundIDs + Ch8], a
 .skip
-	jp Audio2_endchannel
+	jp Audio2_sound_ret
 
-Audio2_dutycycle:
-	cp $fc ; is this command a dutycycle?
+Audio2_duty_cycle_pattern:
+	cp $fc ; is this command a duty_cycle_pattern?
 	jr nz, Audio2_volume ; no
-	call Audio2_GetNextMusicByte ; yes
-	ld b, $0
+	call Audio2_GetNextMusicByte
+	ld b, 0
+	ld hl, wChannelDutyCyclePatterns
+	add hl, bc
+	ld [hl], a ; store full pattern
+	and %11000000
 	ld hl, wChannelDutyCycles
 	add hl, bc
-	ld [hl], a ; store full cycle
-	and $c0
-	ld hl, wChannelDuties
-	add hl, bc
-	ld [hl], a ; store first duty
+	ld [hl], a ; store first duty cycle
 	ld hl, wChannelFlags1
 	add hl, bc
-	set 6, [hl] ; set dutycycle flag
-	jp Audio2_endchannel
+	set BIT_ROTATE_DUTY_CYCLE, [hl]
+	jp Audio2_sound_ret
 
 Audio2_volume:
 	cp $f0 ; is this command a volume?
-	jr nz, Audio2_executemusic ; no
-	call Audio2_GetNextMusicByte ; yes
+	jr nz, Audio2_execute_music ; no
+	call Audio2_GetNextMusicByte
 	ld [rNR50], a ; store volume
-	jp Audio2_endchannel
+	jp Audio2_sound_ret
 
-Audio2_executemusic:
-	cp $f8 ; is this command an executemusic?
+Audio2_execute_music:
+	cp $f8 ; is this command an execute_music?
 	jr nz, Audio2_octave ; no
-	ld b, $0 ; yes
+	ld b, $0
 	ld hl, wChannelFlags2
 	add hl, bc
-	set 0, [hl]
-	jp Audio2_endchannel
+	set BIT_EXECUTE_MUSIC, [hl]
+	jp Audio2_sound_ret
 
 Audio2_octave:
 	and $f0
 	cp $e0 ; is this command an octave?
-	jr nz, Audio2_sfxnote ; no
-	ld hl, wChannelOctaves ; yes
-	ld b, $0
+	jr nz, Audio2_sfx_note ; no
+	ld hl, wChannelOctaves
+	ld b, 0
 	add hl, bc
 	ld a, d
 	and $f
 	ld [hl], a ; store low nibble as octave
-	jp Audio2_endchannel
+	jp Audio2_sound_ret
 
-; sfxnote is either squarenote or noisenote depending on the channel
-Audio2_sfxnote:
-	cp $20 ; is this command an sfxnote?
-	jr nz, Audio2_pitchenvelope ; no
+; sfx_note is either square_note or noise_note depending on the channel
+Audio2_sfx_note:
+	cp $20 ; is this command a sfx_note?
+	jr nz, Audio2_pitch_sweep
 	ld a, c
 	cp Ch4 ; is this a noise or sfx channel?
-	jr c, Audio2_pitchenvelope ; no
-	ld b, $0
+	jr c, Audio2_pitch_sweep ; no
+	ld b, 0
 	ld hl, wChannelFlags2
 	add hl, bc
-	bit 0, [hl]
-	jr nz, Audio2_pitchenvelope ; no
-	call Audio2_notelength
+	bit BIT_EXECUTE_MUSIC, [hl] ; is execute_music being used?
+	jr nz, Audio2_pitch_sweep ; yes
+	call Audio2_note_length
+
+; This code seems to do the same thing as what Audio2_ApplyDutyCycleAndSoundLength
+; does below.
 	ld d, a
-	ld b, $0
-	ld hl, wChannelDuties
+	ld b, 0
+	ld hl, wChannelDutyCycles
 	add hl, bc
 	ld a, [hl]
 	or d
 	ld d, a
-	ld b, $1
-	call Audio2_21ff7
+	ld b, REG_DUTY_SOUND_LEN
+	call Audio2_GetRegisterPointer
 	ld [hl], d
+
 	call Audio2_GetNextMusicByte
 	ld d, a
-	ld b, $2
-	call Audio2_21ff7
+	ld b, REG_VOLUME_ENVELOPE
+	call Audio2_GetRegisterPointer
 	ld [hl], d
 	call Audio2_GetNextMusicByte
 	ld e, a
 	ld a, c
 	cp Ch8
-	ld a, $0
-	jr z, .sfxNoiseChannel ; only two params for noise channel
+	ld a, 0
+	jr z, .skip
+; Channels 1 through 3 have 2 registers that control frequency, but the noise
+; channel a single register (the polynomial counter) that controls frequency,
+; so this command has one less byte on the noise channel.
 	push de
 	call Audio2_GetNextMusicByte
 	pop de
-.sfxNoiseChannel
+.skip
 	ld d, a
 	push de
-	call Audio2_21daa
-	call Audio2_21d79
+	call Audio2_ApplyDutyCycleAndSoundLength
+	call Audio2_EnableChannelOutput
 	pop de
-	call Audio2_21dcc
+	call Audio2_ApplyWavePatternAndFrequency
 	ret
 
-Audio2_pitchenvelope:
+Audio2_pitch_sweep:
 	ld a, c
 	cp Ch5
 	jr c, Audio2_note ; if not a sfx
 	ld a, d
-	cp $10 ; is this command a pitchenvelope?
+	cp $10 ; is this command a pitch_sweep?
 	jr nz, Audio2_note ; no
 	ld b, $0
 	ld hl, wChannelFlags2
 	add hl, bc
-	bit 0, [hl]
+	bit BIT_EXECUTE_MUSIC, [hl]
 	jr nz, Audio2_note ; no
-	call Audio2_GetNextMusicByte ; yes
+	call Audio2_GetNextMusicByte
 	ld [rNR10], a
-	jp Audio2_endchannel
+	jp Audio2_sound_ret
 
 Audio2_note:
 	ld a, c
 	cp Ch4
-	jr nz, Audio2_notelength ; if not noise channel
+	jr nz, Audio2_note_length ; if not noise channel
 	ld a, d
 	and $f0
 	cp $b0 ; is this command a dnote?
-	jr z, Audio2_dnote ; yes
-	jr nc, Audio2_notelength ; no
+	jr z, .dnote
+	jr nc, Audio2_note_length ; no
+
+	; this executes when on the noise channel and
+	; the command id is less than $b0
+	; in this case, the upper nybble is used as the noise instrument ($1-$a)
+	; and the lower nybble is the length minus 1 (0-15)
+	; however, this doesn't work for instrument #2 because the command id
+	; is captured by the noise_note command (command id $2x)
+	; this essentially acts like a dnote command that is only 1 byte
+	; instead of 2 and can only be used with instruments 1 and 3 through 10
+	; this is unused by the game
 	swap a
 	ld b, a
 	ld a, d
@@ -645,38 +679,38 @@
 	ld a, b
 	push de
 	push bc
-	jr asm_21c7e
+	jr .playDnote
 
-Audio2_dnote:
+.dnote
 	ld a, d
 	and $f
 	push af
 	push bc
 	call Audio2_GetNextMusicByte ; get dnote instrument
-asm_21c7e
+.playDnote
 	ld d, a
 	ld a, [wDisableChannelOutputWhenSfxEnds]
 	and a
-	jr nz, .asm_21c89
+	jr nz, .skipDnote
 	ld a, d
 	call Audio2_PlaySound
-.asm_21c89
+.skipDnote
 	pop bc
 	pop de
 
-Audio2_notelength:
+Audio2_note_length:
 	ld a, d
 	push af
 	and $f
 	inc a
-	ld b, $0
-	ld e, a ; store note length (in 16ths)
+	ld b, 0
+	ld e, a  ; store note length (in 16ths)
 	ld d, b
 	ld hl, wChannelNoteSpeeds
 	add hl, bc
 	ld a, [hl]
 	ld l, b
-	call Audio2_22006
+	call Audio2_MultiplyAdd
 	ld a, c
 	cp Ch5
 	jr nc, .sfxChannel
@@ -690,20 +724,20 @@
 	ld e, $0
 	cp Ch8
 	jr z, .skip ; if noise channel
-	call Audio2_21e2f
+	call Audio2_SetSfxTempo
 	ld a, [wSfxTempo]
 	ld d, a
 	ld a, [wSfxTempo + 1]
 	ld e, a
 .skip
-	ld a, l
-	ld b, $0
+	ld a, l ; a = note_length * note_speed
+	ld b, 0
 	ld hl, wChannelNoteDelayCountersFractionalPart
 	add hl, bc
 	ld l, [hl]
-	call Audio2_22006
+	call Audio2_MultiplyAdd
 	ld e, l
-	ld d, h
+	ld d, h ; de = note_delay_frac_part + (note_length * note_speed * tempo)
 	ld hl, wChannelNoteDelayCountersFractionalPart
 	add hl, bc
 	ld [hl], e
@@ -713,16 +747,16 @@
 	ld [hl], a
 	ld hl, wChannelFlags2
 	add hl, bc
-	bit 0, [hl]
-	jr nz, Audio2_notepitch
+	bit BIT_EXECUTE_MUSIC, [hl]
+	jr nz, Audio2_note_pitch
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 2, [hl]
-	jr z, Audio2_notepitch
+	bit BIT_NOISE_OR_SFX, [hl]
+	jr z, Audio2_note_pitch
 	pop hl
 	ret
 
-Audio2_notepitch:
+Audio2_note_pitch:
 	pop af
 	and $f0
 	cp $c0 ; compare to rest
@@ -729,7 +763,8 @@
 	jr nz, .notRest
 	ld a, c
 	cp Ch5
-	jr nc, .sfxChannel
+	jr nc, .next
+; If this isn't an SFX channel, try the corresponding SFX channel.
 	ld hl, wChannelSoundIDs + Ch5
 	add hl, bc
 	ld a, [hl]
@@ -736,113 +771,117 @@
 	and a
 	jr nz, .done
 	; fall through
-.sfxChannel
+.next
 	ld a, c
 	cp Ch3
-	jr z, .musicChannel3
+	jr z, .channel3
 	cp Ch7
-	jr nz, .notSfxChannel3
-.musicChannel3
-	ld b, $0
-	ld hl, Unknown_222de
+	jr nz, .notChannel3
+.channel3
+	ld b, 0
+	ld hl, Audio2_HWChannelDisableMasks
 	add hl, bc
 	ld a, [rNR51]
 	and [hl]
-	ld [rNR51], a
+	ld [rNR51], a ; disable hardware channel 3's output
 	jr .done
-.notSfxChannel3
-	ld b, $2
-	call Audio2_21ff7
-	ld a, $8
+.notChannel3
+	ld b, REG_VOLUME_ENVELOPE
+	call Audio2_GetRegisterPointer
+	ld a, $8 ; fade in sound
 	ld [hli], a
 	inc hl
-	ld a, $80
+	ld a, $80 ; restart sound
 	ld [hl], a
 .done
 	ret
 .notRest
 	swap a
-	ld b, $0
+	ld b, 0
 	ld hl, wChannelOctaves
 	add hl, bc
 	ld b, [hl]
-	call Audio2_22017
-	ld b, $0
+	call Audio2_CalculateFrequency
+	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 4, [hl]
-	jr z, .asm_21d39
-	call Audio2_21f4e
-.asm_21d39
+	bit BIT_PITCH_SLIDE_ON, [hl]
+	jr z, .skipPitchSlide
+	call Audio2_InitPitchSlideVars
+.skipPitchSlide
 	push de
 	ld a, c
 	cp Ch5
-	jr nc, .skip ; if sfx channel
+	jr nc, .sfxChannel ; if sfx channel
+; If this isn't an SFX channel, try the corresponding SFX channel.
 	ld hl, wChannelSoundIDs + Ch5
-	ld d, $0
+	ld d, 0
 	ld e, a
 	add hl, de
 	ld a, [hl]
 	and a
-	jr nz, .asm_21d4c
-	jr .skip
-.asm_21d4c
+	jr nz, .noSfx
+	jr .sfxChannel
+.noSfx
 	pop de
 	ret
-.skip
-	ld b, $0
+.sfxChannel
+	ld b, 0
 	ld hl, wChannelVolumes
 	add hl, bc
 	ld d, [hl]
-	ld b, $2
-	call Audio2_21ff7
+	ld b, REG_VOLUME_ENVELOPE
+	call Audio2_GetRegisterPointer
 	ld [hl], d
-	call Audio2_21daa
-	call Audio2_21d79
+	call Audio2_ApplyDutyCycleAndSoundLength
+	call Audio2_EnableChannelOutput
 	pop de
 	ld b, $0
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 0, [hl]   ; has toggleperfectpitch been used?
-	jr z, .skip2
-	inc e         ; if yes, increment the pitch by 1
-	jr nc, .skip2
+	bit BIT_PERFECT_PITCH, [hl] ; has toggle_perfect_pitch been used?
+	jr z, .skipFrequencyInc
+	inc e                       ; if yes, increment the frequency by 1
+	jr nc, .skipFrequencyInc
 	inc d
-.skip2
+.skipFrequencyInc
 	ld hl, wChannelFrequencyLowBytes
 	add hl, bc
 	ld [hl], e
-	call Audio2_21dcc
+	call Audio2_ApplyWavePatternAndFrequency
 	ret
 
-Audio2_21d79:
-	ld b, $0
-	ld hl, Unknown_222e6
+Audio2_EnableChannelOutput:
+	ld b, 0
+	ld hl, Audio2_HWChannelEnableMasks
 	add hl, bc
 	ld a, [rNR51]
-	or [hl]
+	or [hl] ; set this channel's bits
 	ld d, a
 	ld a, c
 	cp Ch8
-	jr z, .sfxNoiseChannel
+	jr z, .noiseChannelOrNoSfx
 	cp Ch5
 	jr nc, .skip ; if sfx channel
+; If this isn't an SFX channel, try the corresponding SFX channel.
 	ld hl, wChannelSoundIDs + Ch5
 	add hl, bc
 	ld a, [hl]
 	and a
 	jr nz, .skip
-.sfxNoiseChannel
+.noiseChannelOrNoSfx
+; If this is the SFX noise channel or a music channel whose corresponding
+; SFX channel is off, apply stereo panning.
 	ld a, [wStereoPanning]
-	ld hl, Unknown_222e6
+	ld hl, Audio2_HWChannelEnableMasks
 	add hl, bc
 	and [hl]
 	ld d, a
 	ld a, [rNR51]
-	ld hl, Unknown_222de
+	ld hl, Audio2_HWChannelDisableMasks
 	add hl, bc
-	and [hl]
-	or d
+	and [hl] ; reset this channel's output bits
+	or d ; set this channel's output bits that enabled in [wStereoPanning]
 	ld d, a
 .skip
 	ld a, d
@@ -849,47 +888,48 @@
 	ld [rNR51], a
 	ret
 
-Audio2_21daa:
-	ld b, $0
-	ld hl, wChannelNoteDelayCounters
+Audio2_ApplyDutyCycleAndSoundLength:
+	ld b, 0
+	ld hl, wChannelNoteDelayCounters ; use the note delay as sound length
 	add hl, bc
 	ld d, [hl]
 	ld a, c
 	cp Ch3
-	jr z, .channel3 ; if music channel 3
+	jr z, .skipDuty ; if music channel 3
 	cp Ch7
-	jr z, .channel3 ; if sfx channel 3
+	jr z, .skipDuty ; if sfx channel 3
+; include duty cycle (except on channel 3 which doesn't have it)
 	ld a, d
 	and $3f
 	ld d, a
-	ld hl, wChannelDuties
+	ld hl, wChannelDutyCycles
 	add hl, bc
 	ld a, [hl]
 	or d
 	ld d, a
-.channel3
-	ld b, $1
-	call Audio2_21ff7
+.skipDuty
+	ld b, REG_DUTY_SOUND_LEN
+	call Audio2_GetRegisterPointer
 	ld [hl], d
 	ret
 
-Audio2_21dcc:
+Audio2_ApplyWavePatternAndFrequency:
 	ld a, c
 	cp Ch3
 	jr z, .channel3
 	cp Ch7
-	jr nz, .notSfxChannel3
+	jr nz, .notChannel3
 	; fall through
 .channel3
 	push de
 	ld de, wMusicWaveInstrument
 	cp Ch3
-	jr z, .musicChannel3
+	jr z, .next
 	ld de, wSfxWaveInstrument
-.musicChannel3
+.next
 	ld a, [de]
 	add a
-	ld d, $0
+	ld d, 0
 	ld e, a
 	ld hl, Audio2_WavePointers
 	add hl, de
@@ -896,9 +936,9 @@
 	ld e, [hl]
 	inc hl
 	ld d, [hl]
-	ld hl, $ff30
+	ld hl, $ff30 ; wave pattern RAM
 	ld b, $f
-	ld a, $0
+	ld a, $0 ; stop hardware channel 3
 	ld [rNR30], a
 .loop
 	ld a, [de]
@@ -908,155 +948,166 @@
 	dec b
 	and a
 	jr nz, .loop
-	ld a, $80
+	ld a, $80 ; start hardware channel 3
 	ld [rNR30], a
 	pop de
-.notSfxChannel3
+.notChannel3
 	ld a, d
-	or $80
-	and $c7
+	or $80 ; use counter mode (i.e. disable output when the counter reaches 0)
+	and $c7 ; zero the unused bits in the register
 	ld d, a
-	ld b, $3
-	call Audio2_21ff7
-	ld [hl], e
+	ld b, REG_FREQUENCY_LO
+	call Audio2_GetRegisterPointer
+	ld [hl], e ; store frequency low byte
 	inc hl
-	ld [hl], d
+	ld [hl], d ; store frequency high byte
+	; --- this section is only present in this copy of the sound engine
 	ld a, c
 	cp Ch5
 	jr c, .musicChannel
-	call Audio2_21e56
+	call Audio2_ApplyFrequencyModifier
 .musicChannel
+	; ---
 	ret
 
-Audio2_21e19:
+; --- this section is only present in this copy of the sound engine
+; unused
+Audio2_ResetCryModifiers:
 	ld a, c
 	cp Ch5
-	jr nz, .asm_21e2e
+	jr nz, .skip
 	ld a, [wLowHealthAlarm]
 	bit 7, a
-	jr z, .asm_21e2e
+	jr z, .skip
 	xor a
 	ld [wFrequencyModifier], a
 	ld a, $80
 	ld [wTempoModifier], a
-.asm_21e2e
+.skip
 	ret
+; ---
 
-Audio2_21e2f:
-	call Audio2_21e8b
-	jr c, .asm_21e39
-	call Audio2_21e9f
-	jr nc, .asm_21e4c
-.asm_21e39
-	ld d, $0
+Audio2_SetSfxTempo:
+	call Audio2_IsCry
+	jr c, .skipCryCheck
+	call Audio2_IsBattleSFX
+	jr nc, .notCry
+.skipCryCheck
+	ld d, 0
 	ld a, [wTempoModifier]
 	add $80
-	jr nc, .asm_21e43
+	jr nc, .next
 	inc d
-.asm_21e43
+.next
 	ld [wSfxTempo + 1], a
 	ld a, d
 	ld [wSfxTempo], a
-	jr .asm_21e55
-.asm_21e4c
+	jr .done
+.notCry
 	xor a
 	ld [wSfxTempo + 1], a
 	ld a, $1
 	ld [wSfxTempo], a
-.asm_21e55
+.done
 	ret
 
-Audio2_21e56:
-	call Audio2_21e8b
-	jr c, .asm_21e60
-	call Audio2_21e9f
-	jr nc, .asm_21e6c
-.asm_21e60
+Audio2_ApplyFrequencyModifier:
+	call Audio2_IsCry
+	jr c, .skipCryCheck
+	call Audio2_IsBattleSFX
+	jr nc, .done
+.skipCryCheck
+; if playing a cry, add the cry's frequency modifier
 	ld a, [wFrequencyModifier]
 	add e
-	jr nc, .asm_21e67
+	jr nc, .noCarry
 	inc d
-.asm_21e67
+.noCarry
 	dec hl
 	ld e, a
 	ld [hl], e
 	inc hl
 	ld [hl], d
-.asm_21e6c
+.done
 	ret
 
-Audio2_21e6d:
-	call Audio2_21e8b
-	jr nc, .asm_21e88
+Audio2_GoBackOneCommandIfCry:
+	call Audio2_IsCry
+	jr nc, .done
 	ld hl, wChannelCommandPointers
 	ld e, c
-	ld d, $0
+	ld d, 0
 	sla e
 	rl d
 	add hl, de
 	ld a, [hl]
-	sub $1
+	sub 1
 	ld [hl], a
 	inc hl
 	ld a, [hl]
-	sbc $0
+	sbc 0
 	ld [hl], a
 	scf
 	ret
-.asm_21e88
+.done
 	scf
 	ccf
 	ret
 
-Audio2_21e8b:
+Audio2_IsCry:
+; Returns whether the currently playing audio is a cry in carry.
 	ld a, [wChannelSoundIDs + Ch5]
-	cp $14
-	jr nc, .asm_21e94
-	jr .asm_21e9a
-.asm_21e94
-	cp $86
-	jr z, .asm_21e9a
-	jr c, .asm_21e9d
-.asm_21e9a
+	cp CRY_SFX_START
+	jr nc, .next
+	jr .no
+.next
+	cp CRY_SFX_END
+	jr z, .no
+	jr c, .yes
+.no
 	scf
 	ccf
 	ret
-.asm_21e9d
+.yes
 	scf
 	ret
 
-Audio2_21e9f:
+; --- this section is only present in this copy of the sound engine
+Audio2_IsBattleSFX:
+; Returns whether the currently playing audio is a cry in carry.
 	ld a, [wChannelSoundIDs + Ch8]
 	ld b, a
 	ld a, [wChannelSoundIDs + Ch5]
 	or b
-	cp $9d
-	jr nc, .asm_21ead
-	jr .asm_21eb3
-.asm_21ead
-	cp $ea
-	jr z, .asm_21eb3
-	jr c, .asm_21eb6
-.asm_21eb3
+	cp BATTLE_SFX_START
+	jr nc, .next
+	jr .no
+.next
+	cp BATTLE_SFX_END
+	jr z, .no
+	jr c, .yes
+.no
 	scf
 	ccf
 	ret
-.asm_21eb6
+.yes
 	scf
 	ret
+; ---
 
-Audio2_ApplyPitchBend:
+Audio2_ApplyPitchSlide:
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 5, [hl]
-	jp nz, .asm_21eff
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	bit BIT_PITCH_SLIDE_DECREASING, [hl]
+	jp nz, .frequencyDecreasing
+; frequency increasing
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld e, [hl]
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld d, [hl]
-	ld hl, wChannelPitchBendFrequencySteps
+	ld hl, wChannelPitchSlideFrequencySteps
 	add hl, bc
 	ld l, [hl]
 	ld h, b
@@ -1063,41 +1114,41 @@
 	add hl, de
 	ld d, h
 	ld e, l
-	ld hl, wChannelPitchBendCurrentFrequencyFractionalPart
+	ld hl, wChannelPitchSlideCurrentFrequencyFractionalPart
 	add hl, bc
 	push hl
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
 	add hl, bc
 	ld a, [hl]
 	pop hl
 	add [hl]
 	ld [hl], a
-	ld a, $0
+	ld a, 0
 	adc e
 	ld e, a
-	ld a, $0
+	ld a, 0
 	adc d
 	ld d, a
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
 	ld a, [hl]
 	cp d
-	jp c, .asm_21f45
-	jr nz, .asm_21f32
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	jp c, .reachedTargetFrequency
+	jr nz, .applyUpdatedFrequency
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
 	ld a, [hl]
 	cp e
-	jp c, .asm_21f45
-	jr .asm_21f32
-.asm_21eff
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	jp c, .reachedTargetFrequency
+	jr .applyUpdatedFrequency
+.frequencyDecreasing
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld a, [hl]
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld d, [hl]
-	ld hl, wChannelPitchBendFrequencySteps
+	ld hl, wChannelPitchSlideFrequencySteps
 	add hl, bc
 	ld e, [hl]
 	sub e
@@ -1105,7 +1156,7 @@
 	ld a, d
 	sbc b
 	ld d, a
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
 	add hl, bc
 	ld a, [hl]
 	add a
@@ -1116,55 +1167,56 @@
 	ld a, d
 	sbc b
 	ld d, a
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
 	ld a, d
 	cp [hl]
-	jr c, .asm_21f45
-	jr nz, .asm_21f32
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	jr c, .reachedTargetFrequency
+	jr nz, .applyUpdatedFrequency
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
 	ld a, e
 	cp [hl]
-	jr c, .asm_21f45
-.asm_21f32
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	jr c, .reachedTargetFrequency
+.applyUpdatedFrequency
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld [hl], e
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld [hl], d
-	ld b, $3
-	call Audio2_21ff7
+	ld b, REG_FREQUENCY_LO
+	call Audio2_GetRegisterPointer
 	ld a, e
 	ld [hli], a
 	ld [hl], d
 	ret
-.asm_21f45
+.reachedTargetFrequency
+; Turn off pitch slide when the target frequency has been reached.
 	ld hl, wChannelFlags1
 	add hl, bc
-	res 4, [hl]
-	res 5, [hl]
+	res BIT_PITCH_SLIDE_ON, [hl]
+	res BIT_PITCH_SLIDE_DECREASING, [hl]
 	ret
 
-Audio2_21f4e:
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+Audio2_InitPitchSlideVars:
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld [hl], d
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld [hl], e
 	ld hl, wChannelNoteDelayCounters
 	add hl, bc
 	ld a, [hl]
-	ld hl, wChannelPitchBendLengthModifiers
+	ld hl, wChannelPitchSlideLengthModifiers
 	add hl, bc
 	sub [hl]
-	jr nc, .asm_21f66
-	ld a, $1
-.asm_21f66
+	jr nc, .next
+	ld a, 1
+.next
 	ld [hl], a
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
 	ld a, e
 	sub [hl]
@@ -1171,74 +1223,84 @@
 	ld e, a
 	ld a, d
 	sbc b
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
 	sub [hl]
-	jr c, .asm_21f82
+	jr c, .targetFrequencyGreater
 	ld d, a
-	ld b, $0
+	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	set 5, [hl]
-	jr .asm_21fa5
-.asm_21f82
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	set BIT_PITCH_SLIDE_DECREASING, [hl]
+	jr .next2
+.targetFrequencyGreater
+; If the target frequency is greater, subtract the current frequency from
+; the target frequency to get the absolute difference.
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld d, [hl]
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld e, [hl]
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
 	ld a, [hl]
 	sub e
 	ld e, a
+
+; Bug. Instead of borrowing from the high byte of the target frequency as it
+; should, it borrows from the high byte of the current frequency instead.
+; This means that the result will be 0x200 greater than it should be if the
+; low byte of the current frequency is greater than the low byte of the
+; target frequency.
 	ld a, d
 	sbc b
 	ld d, a
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
 	ld a, [hl]
 	sub d
 	ld d, a
-	ld b, $0
+	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	res 5, [hl]
-.asm_21fa5
-	ld hl, wChannelPitchBendLengthModifiers
+	res BIT_PITCH_SLIDE_DECREASING, [hl]
+
+.next2
+	ld hl, wChannelPitchSlideLengthModifiers
 	add hl, bc
-.asm_21fa9
+.divideLoop
 	inc b
 	ld a, e
 	sub [hl]
 	ld e, a
-	jr nc, .asm_21fa9
+	jr nc, .divideLoop
 	ld a, d
 	and a
-	jr z, .asm_21fb7
+	jr z, .doneDividing
 	dec a
 	ld d, a
-	jr .asm_21fa9
-.asm_21fb7
-	ld a, e
+	jr .divideLoop
+.doneDividing
+	ld a, e ; a = remainder - dividend
 	add [hl]
-	ld d, b
-	ld b, $0
-	ld hl, wChannelPitchBendFrequencySteps
+	ld d, b ; d = quotient + 1
+	ld b, 0
+	ld hl, wChannelPitchSlideFrequencySteps
 	add hl, bc
-	ld [hl], d
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
+	ld [hl], d ; store quotient + 1
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
 	add hl, bc
-	ld [hl], a
-	ld hl, wChannelPitchBendCurrentFrequencyFractionalPart
+	ld [hl], a ; store remainder - dividend
+	ld hl, wChannelPitchSlideCurrentFrequencyFractionalPart
 	add hl, bc
-	ld [hl], a
+	ld [hl], a ; store remainder - dividend
 	ret
 
-Audio2_ApplyDutyCycle:
-	ld b, $0
-	ld hl, wChannelDutyCycles
+Audio2_ApplyDutyCyclePattern:
+	ld b, 0
+	ld hl, wChannelDutyCyclePatterns
 	add hl, bc
 	ld a, [hl]
 	rlca
@@ -1246,8 +1308,8 @@
 	ld [hl], a
 	and $c0
 	ld d, a
-	ld b, $1
-	call Audio2_21ff7
+	ld b, REG_DUTY_SOUND_LEN
+	call Audio2_GetRegisterPointer
 	ld a, [hl]
 	and $3f
 	or d
@@ -1255,7 +1317,7 @@
 	ret
 
 Audio2_GetNextMusicByte:
-	ld d, $0
+	ld d, 0
 	ld a, c
 	add a
 	ld e, a
@@ -1272,9 +1334,10 @@
 	ld [hl], d
 	ret
 
-Audio2_21ff7:
+Audio2_GetRegisterPointer:
+; hl = address of hardware sound register b for software channel c
 	ld a, c
-	ld hl, Unknown_222d6
+	ld hl, Audio2_HWChannelBaseAddresses
 	add l
 	jr nc, .noCarry
 	inc h
@@ -1286,13 +1349,14 @@
 	ld h, $ff
 	ret
 
-Audio2_22006:
-	ld h, $0
+Audio2_MultiplyAdd:
+; hl = l + (a * de)
+	ld h, 0
 .loop
 	srl a
-	jr nc, .noCarry
+	jr nc, .skipAdd
 	add hl, de
-.noCarry
+.skipAdd
 	sla e
 	rl d
 	and a
@@ -1301,8 +1365,9 @@
 .done
 	ret
 
-Audio2_22017:
-	ld h, $0
+Audio2_CalculateFrequency:
+; return the frequency for note a, octave b in de
+	ld h, 0
 	ld l, a
 	add hl, hl
 	ld d, h
@@ -1314,7 +1379,7 @@
 	ld d, [hl]
 	ld a, b
 .loop
-	cp Ch8
+	cp 7
 	jr z, .done
 	sra d
 	rr e
@@ -1321,7 +1386,7 @@
 	inc a
 	jr .loop
 .done
-	ld a, $8
+	ld a, 8
 	add d
 	ld d, a
 	ret
@@ -1329,14 +1394,15 @@
 Audio2_PlaySound::
 	ld [wSoundID], a
 	cp $ff
-	jp z, Audio2_221f3
-	cp $e9
-	jp z, Audio2_2210d
-	jp c, Audio2_2210d
+	jp z, .stopAllAudio
+	cp MAX_SFX_ID_2
+	jp z, .playSfx
+	jp c, .playSfx
 	cp $fe
-	jr z, .asm_2204c
-	jp nc, Audio2_2210d
-.asm_2204c
+	jr z, .playMusic
+	jp nc, .playSfx
+
+.playMusic
 	xor a
 	ld [wUnusedC000], a
 	ld [wDisableChannelOutputWhenSfxEnds], a
@@ -1345,53 +1411,53 @@
 	ld [wSfxWaveInstrument], a
 	ld d, $8
 	ld hl, wChannelReturnAddresses
-	call FillAudioRAM2
+	call .FillMem
 	ld hl, wChannelCommandPointers
-	call FillAudioRAM2
+	call .FillMem
 	ld d, $4
 	ld hl, wChannelSoundIDs
-	call FillAudioRAM2
+	call .FillMem
 	ld hl, wChannelFlags1
-	call FillAudioRAM2
-	ld hl, wChannelDuties
-	call FillAudioRAM2
+	call .FillMem
 	ld hl, wChannelDutyCycles
-	call FillAudioRAM2
+	call .FillMem
+	ld hl, wChannelDutyCyclePatterns
+	call .FillMem
 	ld hl, wChannelVibratoDelayCounters
-	call FillAudioRAM2
+	call .FillMem
 	ld hl, wChannelVibratoExtents
-	call FillAudioRAM2
+	call .FillMem
 	ld hl, wChannelVibratoRates
-	call FillAudioRAM2
+	call .FillMem
 	ld hl, wChannelFrequencyLowBytes
-	call FillAudioRAM2
+	call .FillMem
 	ld hl, wChannelVibratoDelayCounterReloadValues
-	call FillAudioRAM2
+	call .FillMem
 	ld hl, wChannelFlags2
-	call FillAudioRAM2
-	ld hl, wChannelPitchBendLengthModifiers
-	call FillAudioRAM2
-	ld hl, wChannelPitchBendFrequencySteps
-	call FillAudioRAM2
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
-	call FillAudioRAM2
-	ld hl, wChannelPitchBendCurrentFrequencyFractionalPart
-	call FillAudioRAM2
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
-	call FillAudioRAM2
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
-	call FillAudioRAM2
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
-	call FillAudioRAM2
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
-	call FillAudioRAM2
+	call .FillMem
+	ld hl, wChannelPitchSlideLengthModifiers
+	call .FillMem
+	ld hl, wChannelPitchSlideFrequencySteps
+	call .FillMem
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
+	call .FillMem
+	ld hl, wChannelPitchSlideCurrentFrequencyFractionalPart
+	call .FillMem
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
+	call .FillMem
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
+	call .FillMem
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
+	call .FillMem
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
+	call .FillMem
 	ld a, $1
 	ld hl, wChannelLoopCounters
-	call FillAudioRAM2
+	call .FillMem
 	ld hl, wChannelNoteDelayCounters
-	call FillAudioRAM2
+	call .FillMem
 	ld hl, wChannelNoteSpeeds
-	call FillAudioRAM2
+	call .FillMem
 	ld [wMusicTempo], a
 	ld a, $ff
 	ld [wStereoPanning], a
@@ -1399,7 +1465,7 @@
 	ld [rNR50], a
 	ld a, $8
 	ld [rNR10], a
-	ld a, $0
+	ld a, 0
 	ld [rNR51], a
 	xor a
 	ld [rNR30], a
@@ -1407,12 +1473,12 @@
 	ld [rNR30], a
 	ld a, $77
 	ld [rNR50], a
-	jp Audio2_2224e
+	jp .playSoundCommon
 
-Audio2_2210d:
+.playSfx
 	ld l, a
 	ld e, a
-	ld h, $0
+	ld h, 0
 	ld d, h
 	add hl, hl
 	add hl, de
@@ -1427,13 +1493,13 @@
 	rlca
 	rlca
 	ld c, a
-.asm_22126
+.sfxChannelLoop
 	ld d, c
 	ld a, c
 	add a
 	add c
 	ld c, a
-	ld b, $0
+	ld b, 0
 	ld a, [wSfxHeaderPointer]
 	ld h, a
 	ld a, [wSfxHeaderPointer + 1]
@@ -1442,32 +1508,32 @@
 	ld c, d
 	ld a, [hl]
 	and $f
-	ld e, a
-	ld d, $0
+	ld e, a ; software channel ID
+	ld d, 0
 	ld hl, wChannelSoundIDs
 	add hl, de
 	ld a, [hl]
 	and a
-	jr z, .asm_22162
+	jr z, .playChannel
 	ld a, e
-	cp $7
-	jr nz, .asm_22159
+	cp Ch8
+	jr nz, .notNoiseChannel
 	ld a, [wSoundID]
-	cp $14
-	jr nc, .asm_22152
+	cp NOISE_INSTRUMENTS_END
+	jr nc, .notNoiseInstrument
 	ret
-.asm_22152
+.notNoiseInstrument
 	ld a, [hl]
-	cp $14
-	jr z, .asm_22162
-	jr c, .asm_22162
-.asm_22159
+	cp NOISE_INSTRUMENTS_END
+	jr z, .playChannel
+	jr c, .playChannel
+.notNoiseChannel
 	ld a, [wSoundID]
 	cp [hl]
-	jr z, .asm_22162
-	jr c, .asm_22162
+	jr z, .playChannel
+	jr c, .playChannel
 	ret
-.asm_22162
+.playChannel
 	xor a
 	push de
 	ld h, d
@@ -1490,10 +1556,10 @@
 	ld hl, wChannelFlags1
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelDuties
+	ld hl, wChannelDutyCycles
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelDutyCycles
+	ld hl, wChannelDutyCyclePatterns
 	add hl, de
 	ld [hl], a
 	ld hl, wChannelVibratoDelayCounters
@@ -1511,28 +1577,28 @@
 	ld hl, wChannelVibratoDelayCounterReloadValues
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendLengthModifiers
+	ld hl, wChannelPitchSlideLengthModifiers
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendFrequencySteps
+	ld hl, wChannelPitchSlideFrequencySteps
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendCurrentFrequencyFractionalPart
+	ld hl, wChannelPitchSlideCurrentFrequencyFractionalPart
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, de
 	ld [hl], a
 	ld hl, wChannelFlags2
@@ -1549,35 +1615,35 @@
 	add hl, de
 	ld [hl], a
 	ld a, e
-	cp $4
-	jr nz, .asm_221ea
+	cp Ch5
+	jr nz, .skipSweepDisable
 	ld a, $8
-	ld [rNR10], a
-.asm_221ea
+	ld [rNR10], a ; sweep off
+.skipSweepDisable
 	ld a, c
 	and a
-	jp z, Audio2_2224e
+	jp z, .playSoundCommon
 	dec c
-	jp .asm_22126
+	jp .sfxChannelLoop
 
-Audio2_221f3:
+.stopAllAudio
 	ld a, $80
-	ld [rNR52], a
-	ld [rNR30], a
+	ld [rNR52], a ; sound hardware on
+	ld [rNR30], a ; wave playback on
 	xor a
-	ld [rNR51], a
-	ld [rNR32], a
+	ld [rNR51], a ; no sound output
+	ld [rNR32], a ; mute channel 3 (wave channel)
 	ld a, $8
-	ld [rNR10], a
-	ld [rNR12], a
-	ld [rNR22], a
-	ld [rNR42], a
+	ld [rNR10], a ; sweep off
+	ld [rNR12], a ; mute channel 1 (pulse channel 1)
+	ld [rNR22], a ; mute channel 2 (pulse channel 2)
+	ld [rNR42], a ; mute channel 4 (noise channel)
 	ld a, $40
-	ld [rNR14], a
+	ld [rNR14], a ; counter mode
 	ld [rNR24], a
 	ld [rNR44], a
 	ld a, $77
-	ld [rNR50], a
+	ld [rNR50], a ; full volume
 	xor a
 	ld [wUnusedC000], a
 	ld [wDisableChannelOutputWhenSfxEnds], a
@@ -1588,11 +1654,11 @@
 	ld [wSfxWaveInstrument], a
 	ld d, $a0
 	ld hl, wChannelCommandPointers
-	call FillAudioRAM2
+	call .FillMem
 	ld a, $1
 	ld d, $18
 	ld hl, wChannelNoteDelayCounters
-	call FillAudioRAM2
+	call .FillMem
 	ld [wMusicTempo], a
 	ld [wSfxTempo], a
 	ld a, $ff
@@ -1600,7 +1666,7 @@
 	ret
 
 ; fills d bytes at hl with a
-FillAudioRAM2:
+.FillMem
 	ld b, d
 .loop
 	ld [hli], a
@@ -1608,11 +1674,11 @@
 	jr nz, .loop
 	ret
 
-Audio2_2224e:
+.playSoundCommon
 	ld a, [wSoundID]
 	ld l, a
 	ld e, a
-	ld h, $0
+	ld h, 0
 	ld d, h
 	add hl, hl
 	add hl, de
@@ -1632,19 +1698,19 @@
 	ld b, c
 	inc b
 	inc de
-	ld c, $0
-.asm_22270
+	ld c, 0
+.commandPointerLoop
 	cp c
-	jr z, .asm_22278
+	jr z, .next
 	inc c
 	inc hl
 	inc hl
-	jr .asm_22270
-.asm_22278
+	jr .commandPointerLoop
+.next
 	push hl
 	push bc
 	push af
-	ld b, $0
+	ld b, 0
 	ld c, a
 	ld hl, wChannelSoundIDs
 	add hl, bc
@@ -1651,12 +1717,12 @@
 	ld a, [wSoundID]
 	ld [hl], a
 	pop af
-	cp $3
-	jr c, .asm_22291
+	cp Ch4
+	jr c, .skipSettingFlag
 	ld hl, wChannelFlags1
 	add hl, bc
-	set 2, [hl]
-.asm_22291
+	set BIT_NOISE_OR_SFX, [hl]
+.skipSettingFlag
 	pop bc
 	pop hl
 	ld a, [de] ; get channel pointer
@@ -1671,52 +1737,53 @@
 	and a
 	ld a, [de]
 	inc de
-	jr nz, .asm_22270
+	jr nz, .commandPointerLoop
 	ld a, [wSoundID]
-	cp $14
-	jr nc, .asm_222aa
-	jr .asm_222d4
-.asm_222aa
+	cp CRY_SFX_START
+	jr nc, .maybeCry
+	jr .done
+.maybeCry
 	ld a, [wSoundID]
-	cp $86
-	jr z, .asm_222d4
-	jr c, .asm_222b5
-	jr .asm_222d4
-.asm_222b5
+	cp CRY_SFX_END
+	jr z, .done
+	jr c, .cry
+	jr .done
+.cry
 	ld hl, wChannelSoundIDs + Ch5
 	ld [hli], a
 	ld [hli], a
 	ld [hli], a
 	ld [hl], a
-	ld hl, wChannelCommandPointers + Ch7 * 2 ; sfx noise channel pointer
-	ld de, Noise2_endchannel
+	ld hl, wChannelCommandPointers + Ch7 * 2 ; sfx wave channel pointer
+	ld de, Audio2_CryRet
 	ld [hl], e
 	inc hl
-	ld [hl], d ; overwrite pointer to point to endchannel
+	ld [hl], d ; overwrite pointer to point to sound_ret
 	ld a, [wSavedVolume]
 	and a
-	jr nz, .asm_222d4
+	jr nz, .done
 	ld a, [rNR50]
 	ld [wSavedVolume], a
 	ld a, $77
-	ld [rNR50], a
-.asm_222d4
+	ld [rNR50], a ; full volume
+.done
 	ret
 
-Noise2_endchannel:
+Audio2_CryRet:
 	sound_ret
 
-Unknown_222d6:
-	db $10, $15, $1A, $1F ; channels 0-3
-	db $10, $15, $1A, $1F ; channels 4-7
+Audio2_HWChannelBaseAddresses:
+; the low bytes of each HW channel's base address
+	db HW_CH1_BASE, HW_CH2_BASE, HW_CH3_BASE, HW_CH4_BASE ; channels 0-3
+	db HW_CH1_BASE, HW_CH2_BASE, HW_CH3_BASE, HW_CH4_BASE ; channels 4-7
 
-Unknown_222de:
-	db $EE, $DD, $BB, $77 ; channels 0-3
-	db $EE, $DD, $BB, $77 ; channels 4-7
+Audio2_HWChannelDisableMasks:
+	db HW_CH1_DISABLE_MASK, HW_CH2_DISABLE_MASK, HW_CH3_DISABLE_MASK, HW_CH4_DISABLE_MASK ; channels 0-3
+	db HW_CH1_DISABLE_MASK, HW_CH2_DISABLE_MASK, HW_CH3_DISABLE_MASK, HW_CH4_DISABLE_MASK ; channels 4-7
 
-Unknown_222e6:
-	db $11, $22, $44, $88 ; channels 0-3
-	db $11, $22, $44, $88 ; channels 4-7
+Audio2_HWChannelEnableMasks:
+	db HW_CH1_ENABLE_MASK, HW_CH2_ENABLE_MASK, HW_CH3_ENABLE_MASK, HW_CH4_ENABLE_MASK ; channels 0-3
+	db HW_CH1_ENABLE_MASK, HW_CH2_ENABLE_MASK, HW_CH3_ENABLE_MASK, HW_CH4_ENABLE_MASK ; channels 4-7
 
 Audio2_Pitches:
 	dw $F82C ; C_
@@ -1731,5 +1798,3 @@
 	dw $FB58 ; A_
 	dw $FB9B ; A#
 	dw $FBDA ; B_
-
-
--- a/audio/engine_3.asm
+++ b/audio/engine_3.asm
@@ -3,7 +3,7 @@
 Audio3_UpdateMusic::
 	ld c, Ch1
 .loop
-	ld b, $0
+	ld b, 0
 	ld hl, wChannelSoundIDs
 	add hl, bc
 	ld a, [hl]
@@ -19,7 +19,7 @@
 	jr nz, .nextChannel
 	set 7, a
 	ld [wMuteAudioAndPauseMusic], a
-	xor a
+	xor a ; disable all channels' output
 	ld [rNR51], a
 	ld [rNR30], a
 	ld a, $80
@@ -36,18 +36,12 @@
 
 ; this routine checks flags for music effects currently applied
 ; to the channel and calls certain functions based on flags.
-; known flags for wChannelFlags1:
-;   0: toggleperfectpitch has been used
-;   1: call has been used
-;   3: a toggle used only by this routine for vibrato
-;   4: pitchbend flag
-;   6: dutycycle flag
 Audio3_ApplyMusicAffects:
 	ld b, $0
 	ld hl, wChannelNoteDelayCounters ; delay until next note
 	add hl, bc
 	ld a, [hl]
-	cp $1 ; if delay is 1, play next note
+	cp $1 ; if the delay is 1, play next note
 	jp z, Audio3_PlayNextNote
 	dec a ; otherwise, decrease the delay timer
 	ld [hl], a
@@ -63,36 +57,36 @@
 .startChecks
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 6, [hl] ; dutycycle
+	bit BIT_ROTATE_DUTY_CYCLE, [hl]
 	jr z, .checkForExecuteMusic
-	call Audio3_ApplyDutyCycle
+	call Audio3_ApplyDutyCyclePattern
 .checkForExecuteMusic
-	ld b, $0
+	ld b, 0
 	ld hl, wChannelFlags2
 	add hl, bc
-	bit 0, [hl]
-	jr nz, .checkForPitchBend
+	bit BIT_EXECUTE_MUSIC, [hl]
+	jr nz, .checkForPitchSlide
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 2, [hl]
-	jr nz, .disablePitchBendVibrato
-.checkForPitchBend
+	bit BIT_NOISE_OR_SFX, [hl]
+	jr nz, .skipPitchSlideVibrato
+.checkForPitchSlide
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 4, [hl] ; pitchbend
+	bit BIT_PITCH_SLIDE_ON, [hl]
 	jr z, .checkVibratoDelay
-	jp Audio3_ApplyPitchBend
+	jp Audio3_ApplyPitchSlide
 .checkVibratoDelay
-	ld hl, wChannelVibratoDelayCounters ; vibrato delay
+	ld hl, wChannelVibratoDelayCounters
 	add hl, bc
 	ld a, [hl]
 	and a ; check if delay is over
 	jr z, .checkForVibrato
 	dec [hl] ; otherwise, dec delay
-.disablePitchBendVibrato
+.skipPitchSlideVibrato
 	ret
 .checkForVibrato
-	ld hl, wChannelVibratoExtents ; vibrato rate
+	ld hl, wChannelVibratoExtents
 	add hl, bc
 	ld a, [hl]
 	and a
@@ -105,22 +99,24 @@
 	ld a, [hl]
 	and $f
 	and a
-	jr z, .vibratoAlreadyDone
-	dec [hl] ; apply vibrato pitch change
+	jr z, .applyVibrato
+	dec [hl] ; decrement counter
 	ret
-.vibratoAlreadyDone
+.applyVibrato
 	ld a, [hl]
 	swap [hl]
 	or [hl]
-	ld [hl], a ; reset the vibrato value and start again
+	ld [hl], a ; reload the counter
 	ld hl, wChannelFrequencyLowBytes
 	add hl, bc
 	ld e, [hl] ; get note pitch
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 3, [hl] ; this is the only code that sets/resets bit three so
-	jr z, .unset ; it continuously alternates which path it takes
-	res 3, [hl]
+; This is the only code that sets/resets the vibrato direction bit, so it
+; continuously alternates which path it takes.
+	bit BIT_VIBRATO_DIRECTION, [hl]
+	jr z, .unset
+	res BIT_VIBRATO_DIRECTION, [hl]
 	ld a, d
 	and $f
 	ld d, a
@@ -127,11 +123,11 @@
 	ld a, e
 	sub d
 	jr nc, .noCarry
-	ld a, $0
+	ld a, 0
 .noCarry
 	jr .done
 .unset
-	set 3, [hl]
+	set BIT_VIBRATO_DIRECTION, [hl]
 	ld a, d
 	and $f0
 	swap a
@@ -140,15 +136,16 @@
 	ld a, $ff
 .done
 	ld d, a
-	ld b, $3
-	call Audio3_7d8ac
+	ld b, REG_FREQUENCY_LO
+	call Audio3_GetRegisterPointer
 	ld [hl], d
 	ret
 
 ; this routine executes all music commands that take up no time,
-; like tempo changes, duty changes etc. and doesn't return
+; like tempo changes, duty cycle changes etc. and doesn't return
 ; until the first note is reached
 Audio3_PlayNextNote:
+; reload the vibrato delay counter
 	ld hl, wChannelVibratoDelayCounterReloadValues
 	add hl, bc
 	ld a, [hl]
@@ -155,48 +152,50 @@
 	ld hl, wChannelVibratoDelayCounters
 	add hl, bc
 	ld [hl], a
+
 	ld hl, wChannelFlags1
 	add hl, bc
-	res 4, [hl]
-	res 5, [hl]
-	call Audio3_endchannel
+	res BIT_PITCH_SLIDE_ON, [hl]
+	res BIT_PITCH_SLIDE_DECREASING, [hl]
+	call Audio3_sound_ret
 	ret
 
-Audio3_endchannel:
+Audio3_sound_ret:
 	call Audio3_GetNextMusicByte
 	ld d, a
-	cp $ff ; is this command an endchannel?
-	jp nz, Audio3_callchannel ; no
-	ld b, $0 ; yes
+	cp $ff ; is this command a sound_ret?
+	jp nz, Audio3_sound_call ; no
+	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 1, [hl]
+	bit BIT_SOUND_CALL, [hl]
 	jr nz, .returnFromCall
 	ld a, c
 	cp Ch4
 	jr nc, .noiseOrSfxChannel
-	jr .asm_7d2b3
+	jr .disableChannelOutput
 .noiseOrSfxChannel
-	res 2, [hl]
+	res BIT_NOISE_OR_SFX, [hl]
 	ld hl, wChannelFlags2
 	add hl, bc
-	res 0, [hl]
+	res BIT_EXECUTE_MUSIC, [hl]
 	cp Ch7
-	jr nz, .notSfxChannel3
+	jr nz, .skipSfxChannel3
+; restart hardware channel 3 (wave channel) output
 	ld a, $0
 	ld [rNR30], a
 	ld a, $80
 	ld [rNR30], a
-.notSfxChannel3
-	jr nz, .asm_7d296
+.skipSfxChannel3
+	jr nz, .dontDisable
 	ld a, [wDisableChannelOutputWhenSfxEnds]
 	and a
-	jr z, .asm_7d296
+	jr z, .dontDisable
 	xor a
 	ld [wDisableChannelOutputWhenSfxEnds], a
-	jr .asm_7d2b3
-.asm_7d296
-	jr .asm_7d2bc
+	jr .disableChannelOutput
+.dontDisable
+	jr .afterDisable
 .returnFromCall
 	res 1, [hl]
 	ld d, $0
@@ -216,45 +215,45 @@
 	inc de
 	ld a, [de]
 	ld [hl], a ; loads channel address to return to
-	jp Audio3_endchannel
-.asm_7d2b3
-	ld hl, Unknown_7db93
+	jp Audio3_sound_ret
+.disableChannelOutput
+	ld hl, Audio3_HWChannelDisableMasks
 	add hl, bc
 	ld a, [rNR51]
 	and [hl]
 	ld [rNR51], a
-.asm_7d2bc
+.afterDisable
 	ld a, [wChannelSoundIDs + Ch5]
-	cp $14
-	jr nc, .asm_7d2c5
-	jr .asm_7d2e2
-.asm_7d2c5
+	cp CRY_SFX_START
+	jr nc, .maybeCry
+	jr .skipCry
+.maybeCry
 	ld a, [wChannelSoundIDs + Ch5]
-	cp $86
-	jr z, .asm_7d2e2
-	jr c, .asm_7d2d0
-	jr .asm_7d2e2
-.asm_7d2d0
+	cp CRY_SFX_END
+	jr z, .skipCry
+	jr c, .cry
+	jr .skipCry
+.cry
 	ld a, c
 	cp Ch5
-	jr z, .asm_7d2d9
-	call Audio3_7d73b
+	jr z, .skipRewind
+	call Audio3_GoBackOneCommandIfCry
 	ret c
-.asm_7d2d9
+.skipRewind
 	ld a, [wSavedVolume]
 	ld [rNR50], a
 	xor a
 	ld [wSavedVolume], a
-.asm_7d2e2
+.skipCry
 	ld hl, wChannelSoundIDs
 	add hl, bc
 	ld [hl], b
 	ret
 
-Audio3_callchannel:
-	cp $fd ; is this command a callchannel?
-	jp nz, Audio3_loopchannel ; no
-	call Audio3_GetNextMusicByte ; yes
+Audio3_sound_call:
+	cp $fd ; is this command a sound_call?
+	jp nz, Audio3_sound_loop ; no
+	call Audio3_GetNextMusicByte
 	push af
 	call Audio3_GetNextMusicByte
 	ld d, a
@@ -285,27 +284,27 @@
 	ld b, $0
 	ld hl, wChannelFlags1
 	add hl, bc
-	set 1, [hl] ; set the call flag
-	jp Audio3_endchannel
+	set BIT_SOUND_CALL, [hl] ; set the call flag
+	jp Audio3_sound_ret
 
-Audio3_loopchannel:
-	cp $fe ; is this command a loopchannel?
-	jp nz, Audio3_notetype ; no
-	call Audio3_GetNextMusicByte ; yes
+Audio3_sound_loop:
+	cp $fe ; is this command a sound_loop?
+	jp nz, Audio3_note_type ; no
+	call Audio3_GetNextMusicByte
 	ld e, a
 	and a
 	jr z, .infiniteLoop
-	ld b, $0
+	ld b, 0
 	ld hl, wChannelLoopCounters
 	add hl, bc
 	ld a, [hl]
 	cp e
 	jr nz, .loopAgain
-	ld a, $1 ; if no more loops to make
+	ld a, $1 ; if no more loops to make,
 	ld [hl], a
 	call Audio3_GetNextMusicByte ; skip pointer
 	call Audio3_GetNextMusicByte
-	jp Audio3_endchannel
+	jp Audio3_sound_ret
 .loopAgain ; inc loop count
 	inc a
 	ld [hl], a
@@ -324,13 +323,13 @@
 	pop af
 	ld [hli], a
 	ld [hl], b
-	jp Audio3_endchannel
+	jp Audio3_sound_ret
 
-Audio3_notetype:
+Audio3_note_type:
 	and $f0
-	cp $d0 ; is this command a notetype?
-	jp nz, Audio3_toggleperfectpitch ; no
-	ld a, d ; yes
+	cp $d0 ; is this command a note_type?
+	jp nz, Audio3_toggle_perfect_pitch ; no
+	ld a, d
 	and $f
 	ld b, $0
 	ld hl, wChannelNoteSpeeds
@@ -345,15 +344,15 @@
 	cp Ch3
 	jr z, .musicChannel3
 	cp Ch7
-	jr nz, .notChannel3
+	jr nz, .skipChannel3
 	ld hl, wSfxWaveInstrument
-	jr .sfxChannel3
+	jr .channel3
 .musicChannel3
 	ld hl, wMusicWaveInstrument
-.sfxChannel3
+.channel3
 	ld a, d
 	and $f
-	ld [hl], a ; store low nibble of param as duty
+	ld [hl], a ; store low nibble of param as wave instrument
 	ld a, d
 	and $30
 	sla a
@@ -362,31 +361,31 @@
 
 	; if channel 3, store high nibble as volume
 	; else, store volume (high nibble) and fade (low nibble)
-.notChannel3
-	ld b, $0
+.skipChannel3
+	ld b, 0
 	ld hl, wChannelVolumes
 	add hl, bc
 	ld [hl], d
 .noiseChannel
-	jp Audio3_endchannel
+	jp Audio3_sound_ret
 
-Audio3_toggleperfectpitch:
+Audio3_toggle_perfect_pitch:
 	ld a, d
-	cp $e8 ; is this command a toggleperfectpitch?
+	cp $e8 ; is this command a toggle_perfect_pitch?
 	jr nz, Audio3_vibrato ; no
-	ld b, $0 ; yes
+	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
 	ld a, [hl]
 	xor $1
 	ld [hl], a ; flip bit 0 of wChannelFlags1
-	jp Audio3_endchannel
+	jp Audio3_sound_ret
 
 Audio3_vibrato:
 	cp $ea ; is this command a vibrato?
-	jr nz, Audio3_pitchbend ; no
-	call Audio3_GetNextMusicByte ; yes
-	ld b, $0
+	jr nz, Audio3_pitch_slide ; no
+	call Audio3_GetNextMusicByte
+	ld b, 0
 	ld hl, wChannelVibratoDelayCounters
 	add hl, bc
 	ld [hl], a ; store delay
@@ -395,9 +394,16 @@
 	ld [hl], a ; store delay
 	call Audio3_GetNextMusicByte
 	ld d, a
+
+; The high nybble of the command byte is the extent of the vibrato.
+; Let n be the extent.
+; The upper nybble of the channel's byte in the wChannelVibratoExtents
+; array will store the extent above the note: (n / 2) + (n % 2).
+; The lower nybble will store the extent below the note: (n / 2).
+; These two values add to the total extent, n.
 	and $f0
 	swap a
-	ld b, $0
+	ld b, 0
 	ld hl, wChannelVibratoExtents
 	add hl, bc
 	srl a
@@ -405,7 +411,13 @@
 	adc b
 	swap a
 	or e
-	ld [hl], a ; store rate as both high and low nibbles
+	ld [hl], a
+
+; The low nybble of the command byte is the rate of the vibrato.
+; The high and low nybbles of the channel's byte in the wChannelVibratoRates
+; array are both initialised to this value because the high nybble is the
+; counter reload value and the low nybble is the counter itself, which should
+; start at its value upon reload.
 	ld a, d
 	and $f
 	ld d, a
@@ -413,17 +425,18 @@
 	add hl, bc
 	swap a
 	or d
-	ld [hl], a ; store depth as both high and low nibbles
-	jp Audio3_endchannel
+	ld [hl], a
 
-Audio3_pitchbend:
-	cp $eb ; is this command a pitchbend?
-	jr nz, Audio3_duty ; no
-	call Audio3_GetNextMusicByte ; yes
-	ld b, $0
-	ld hl, wChannelPitchBendLengthModifiers
+	jp Audio3_sound_ret
+
+Audio3_pitch_slide:
+	cp $eb ; is this command a pitch_slide?
+	jr nz, Audio3_duty_cycle ; no
+	call Audio3_GetNextMusicByte
+	ld b, 0
+	ld hl, wChannelPitchSlideLengthModifiers
 	add hl, bc
-	ld [hl], a ; store first param
+	ld [hl], a
 	call Audio3_GetNextMusicByte
 	ld d, a
 	and $f0
@@ -431,39 +444,39 @@
 	ld b, a
 	ld a, d
 	and $f
-	call Audio3_7d8cc
-	ld b, $0
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	call Audio3_CalculateFrequency
+	ld b, 0
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
-	ld [hl], d ; store unknown part of second param
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld [hl], d
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
-	ld [hl], e ; store unknown part of second param
-	ld b, $0
+	ld [hl], e
+	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	set 4, [hl] ; set pitchbend flag
+	set BIT_PITCH_SLIDE_ON, [hl]
 	call Audio3_GetNextMusicByte
 	ld d, a
-	jp Audio3_notelength
+	jp Audio3_note_length
 
-Audio3_duty:
-	cp $ec ; is this command a duty?
+Audio3_duty_cycle:
+	cp $ec ; is this command a duty_cycle?
 	jr nz, Audio3_tempo ; no
-	call Audio3_GetNextMusicByte ; yes
+	call Audio3_GetNextMusicByte
 	rrca
 	rrca
 	and $c0
-	ld b, $0
-	ld hl, wChannelDuties
+	ld b, 0
+	ld hl, wChannelDutyCycles
 	add hl, bc
-	ld [hl], a ; store duty
-	jp Audio3_endchannel
+	ld [hl], a ; store duty cycle
+	jp Audio3_sound_ret
 
 Audio3_tempo:
 	cp $ed ; is this command a tempo?
-	jr nz, Audio3_stereopanning ; no
-	ld a, c ; yes
+	jr nz, Audio3_stereo_panning ; no
+	ld a, c
 	cp Ch5
 	jr nc, .sfxChannel
 	call Audio3_GetNextMusicByte
@@ -487,20 +500,20 @@
 	ld [wChannelNoteDelayCountersFractionalPart + 6], a
 	ld [wChannelNoteDelayCountersFractionalPart + 7], a
 .musicChannelDone
-	jp Audio3_endchannel
+	jp Audio3_sound_ret
 
-Audio3_stereopanning:
-	cp $ee ; is this command a stereopanning?
+Audio3_stereo_panning:
+	cp $ee ; is this command a stereo_panning?
 	jr nz, Audio3_unknownmusic0xef ; no
-	call Audio3_GetNextMusicByte ; yes
+	call Audio3_GetNextMusicByte
 	ld [wStereoPanning], a ; store panning
-	jp Audio3_endchannel
+	jp Audio3_sound_ret
 
 ; this appears to never be used
 Audio3_unknownmusic0xef:
 	cp $ef ; is this command an unknownmusic0xef?
-	jr nz, Audio3_dutycycle ; no
-	call Audio3_GetNextMusicByte ; yes
+	jr nz, Audio3_duty_cycle_pattern ; no
+	call Audio3_GetNextMusicByte
 	push bc
 	call Audio3_PlaySound
 	pop bc
@@ -512,124 +525,141 @@
 	xor a
 	ld [wChannelSoundIDs + Ch8], a
 .skip
-	jp Audio3_endchannel
+	jp Audio3_sound_ret
 
-Audio3_dutycycle:
-	cp $fc ; is this command a dutycycle?
+Audio3_duty_cycle_pattern:
+	cp $fc ; is this command a duty_cycle_pattern?
 	jr nz, Audio3_volume ; no
-	call Audio3_GetNextMusicByte ; yes
-	ld b, $0
+	call Audio3_GetNextMusicByte
+	ld b, 0
+	ld hl, wChannelDutyCyclePatterns
+	add hl, bc
+	ld [hl], a ; store full pattern
+	and %11000000
 	ld hl, wChannelDutyCycles
 	add hl, bc
-	ld [hl], a ; store full cycle
-	and $c0
-	ld hl, wChannelDuties
-	add hl, bc
-	ld [hl], a ; store first duty
+	ld [hl], a ; store first duty cycle
 	ld hl, wChannelFlags1
 	add hl, bc
-	set 6, [hl] ; set duty flag
-	jp Audio3_endchannel
+	set BIT_ROTATE_DUTY_CYCLE, [hl]
+	jp Audio3_sound_ret
 
 Audio3_volume:
 	cp $f0 ; is this command a volume?
-	jr nz, Audio3_executemusic ; no
-	call Audio3_GetNextMusicByte ; yes
+	jr nz, Audio3_execute_music ; no
+	call Audio3_GetNextMusicByte
 	ld [rNR50], a ; store volume
-	jp Audio3_endchannel
+	jp Audio3_sound_ret
 
-Audio3_executemusic:
-	cp $f8 ; is this command an executemusic?
+Audio3_execute_music:
+	cp $f8 ; is this command an execute_music?
 	jr nz, Audio3_octave ; no
-	ld b, $0 ; yes
+	ld b, $0
 	ld hl, wChannelFlags2
 	add hl, bc
-	set 0, [hl]
-	jp Audio3_endchannel
+	set BIT_EXECUTE_MUSIC, [hl]
+	jp Audio3_sound_ret
 
 Audio3_octave:
 	and $f0
 	cp $e0 ; is this command an octave?
-	jr nz, Audio3_sfxnote ; no
-	ld hl, wChannelOctaves ; yes
-	ld b, $0
+	jr nz, Audio3_sfx_note ; no
+	ld hl, wChannelOctaves
+	ld b, 0
 	add hl, bc
 	ld a, d
 	and $f
 	ld [hl], a ; store low nibble as octave
-	jp Audio3_endchannel
+	jp Audio3_sound_ret
 
-; sfxnote is either squarenote or noisenote depending on the channel
-Audio3_sfxnote:
-	cp $20 ; is this command an sfxnote?
-	jr nz, Audio3_pitchenvelope ; no
+; sfx_note is either square_note or noise_note depending on the channel
+Audio3_sfx_note:
+	cp $20 ; is this command a sfx_note?
+	jr nz, Audio3_pitch_sweep
 	ld a, c
 	cp Ch4 ; is this a noise or sfx channel?
-	jr c, Audio3_pitchenvelope ; no
-	ld b, $0
+	jr c, Audio3_pitch_sweep ; no
+	ld b, 0
 	ld hl, wChannelFlags2
 	add hl, bc
-	bit 0, [hl]
-	jr nz, Audio3_pitchenvelope ; no
-	call Audio3_notelength ; yes
+	bit BIT_EXECUTE_MUSIC, [hl] ; is execute_music being used?
+	jr nz, Audio3_pitch_sweep ; yes
+	call Audio3_note_length
+
+; This code seems to do the same thing as what Audio3_ApplyDutyCycleAndSoundLength
+; does below.
 	ld d, a
-	ld b, $0
-	ld hl, wChannelDuties
+	ld b, 0
+	ld hl, wChannelDutyCycles
 	add hl, bc
 	ld a, [hl]
 	or d
 	ld d, a
-	ld b, $1
-	call Audio3_7d8ac
+	ld b, REG_DUTY_SOUND_LEN
+	call Audio3_GetRegisterPointer
 	ld [hl], d
+
 	call Audio3_GetNextMusicByte
 	ld d, a
-	ld b, $2
-	call Audio3_7d8ac
+	ld b, REG_VOLUME_ENVELOPE
+	call Audio3_GetRegisterPointer
 	ld [hl], d
 	call Audio3_GetNextMusicByte
 	ld e, a
 	ld a, c
 	cp Ch8
-	ld a, $0
-	jr z, .sfxNoiseChannel ; only two params for noise channel
+	ld a, 0
+	jr z, .skip
+; Channels 1 through 3 have 2 registers that control frequency, but the noise
+; channel a single register (the polynomial counter) that controls frequency,
+; so this command has one less byte on the noise channel.
 	push de
 	call Audio3_GetNextMusicByte
 	pop de
-.sfxNoiseChannel
+.skip
 	ld d, a
 	push de
-	call Audio3_7d69d
-	call Audio3_7d66c
+	call Audio3_ApplyDutyCycleAndSoundLength
+	call Audio3_EnableChannelOutput
 	pop de
-	call Audio3_7d6bf
+	call Audio3_ApplyWavePatternAndFrequency
 	ret
 
-Audio3_pitchenvelope:
+Audio3_pitch_sweep:
 	ld a, c
 	cp Ch5
 	jr c, Audio3_note ; if not a sfx
 	ld a, d
-	cp $10 ; is this command an pitchenvelope?
+	cp $10 ; is this command a pitch_sweep?
 	jr nz, Audio3_note ; no
 	ld b, $0
 	ld hl, wChannelFlags2
 	add hl, bc
-	bit 0, [hl]
+	bit BIT_EXECUTE_MUSIC, [hl]
 	jr nz, Audio3_note ; no
-	call Audio3_GetNextMusicByte ; yes
+	call Audio3_GetNextMusicByte
 	ld [rNR10], a
-	jp Audio3_endchannel
+	jp Audio3_sound_ret
 
 Audio3_note:
 	ld a, c
 	cp Ch4
-	jr nz, Audio3_notelength ; if not noise channel
+	jr nz, Audio3_note_length ; if not noise channel
 	ld a, d
 	and $f0
 	cp $b0 ; is this command a dnote?
-	jr z, Audio3_dnote ; yes
-	jr nc, Audio3_notelength ; no
+	jr z, .dnote
+	jr nc, Audio3_note_length ; no
+
+	; this executes when on the noise channel and
+	; the command id is less than $b0
+	; in this case, the upper nybble is used as the noise instrument ($1-$a)
+	; and the lower nybble is the length minus 1 (0-15)
+	; however, this doesn't work for instrument #2 because the command id
+	; is captured by the noise_note command (command id $2x)
+	; this essentially acts like a dnote command that is only 1 byte
+	; instead of 2 and can only be used with instruments 1 and 3 through 10
+	; this is unused by the game
 	swap a
 	ld b, a
 	ld a, d
@@ -638,31 +668,31 @@
 	ld a, b
 	push de
 	push bc
-	jr asm_7d571
+	jr .playDnote
 
-Audio3_dnote:
+.dnote
 	ld a, d
 	and $f
 	push af
 	push bc
 	call Audio3_GetNextMusicByte ; get dnote instrument
-asm_7d571
+.playDnote
 	ld d, a
 	ld a, [wDisableChannelOutputWhenSfxEnds]
 	and a
-	jr nz, .asm_7d57c
+	jr nz, .skipDnote
 	ld a, d
 	call Audio3_PlaySound
-.asm_7d57c
+.skipDnote
 	pop bc
 	pop de
 
-Audio3_notelength:
+Audio3_note_length:
 	ld a, d
 	push af
 	and $f
 	inc a
-	ld b, $0
+	ld b, 0
 	ld e, a  ; store note length (in 16ths)
 	ld d, b
 	ld hl, wChannelNoteSpeeds
@@ -669,7 +699,7 @@
 	add hl, bc
 	ld a, [hl]
 	ld l, b
-	call Audio3_7d8bb
+	call Audio3_MultiplyAdd
 	ld a, c
 	cp Ch5
 	jr nc, .sfxChannel
@@ -683,20 +713,20 @@
 	ld e, $0
 	cp Ch8
 	jr z, .skip ; if noise channel
-	call Audio3_7d707
+	call Audio3_SetSfxTempo
 	ld a, [wSfxTempo]
 	ld d, a
 	ld a, [wSfxTempo + 1]
 	ld e, a
 .skip
-	ld a, l
-	ld b, $0
+	ld a, l ; a = note_length * note_speed
+	ld b, 0
 	ld hl, wChannelNoteDelayCountersFractionalPart
 	add hl, bc
 	ld l, [hl]
-	call Audio3_7d8bb
+	call Audio3_MultiplyAdd
 	ld e, l
-	ld d, h
+	ld d, h ; de = note_delay_frac_part + (note_length * note_speed * tempo)
 	ld hl, wChannelNoteDelayCountersFractionalPart
 	add hl, bc
 	ld [hl], e
@@ -706,16 +736,16 @@
 	ld [hl], a
 	ld hl, wChannelFlags2
 	add hl, bc
-	bit 0, [hl]
-	jr nz, Audio3_notepitch
+	bit BIT_EXECUTE_MUSIC, [hl]
+	jr nz, Audio3_note_pitch
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 2, [hl]
-	jr z, Audio3_notepitch
+	bit BIT_NOISE_OR_SFX, [hl]
+	jr z, Audio3_note_pitch
 	pop hl
 	ret
 
-Audio3_notepitch:
+Audio3_note_pitch:
 	pop af
 	and $f0
 	cp $c0 ; compare to rest
@@ -722,120 +752,125 @@
 	jr nz, .notRest
 	ld a, c
 	cp Ch5
-	jr nc, .sfxChannel
+	jr nc, .next
+; If this isn't an SFX channel, try the corresponding SFX channel.
 	ld hl, wChannelSoundIDs + Ch5
 	add hl, bc
 	ld a, [hl]
 	and a
-	jr nz, .quit
+	jr nz, .done
 	; fall through
-.sfxChannel
+.next
 	ld a, c
 	cp Ch3
-	jr z, .musicChannel3
+	jr z, .channel3
 	cp Ch7
-	jr nz, .notSfxChannel3
-.musicChannel3
-	ld b, $0
-	ld hl, Unknown_7db93
+	jr nz, .notChannel3
+.channel3
+	ld b, 0
+	ld hl, Audio3_HWChannelDisableMasks
 	add hl, bc
 	ld a, [rNR51]
 	and [hl]
-	ld [rNR51], a
-	jr .quit
-.notSfxChannel3
-	ld b, $2
-	call Audio3_7d8ac
-	ld a, $8
+	ld [rNR51], a ; disable hardware channel 3's output
+	jr .done
+.notChannel3
+	ld b, REG_VOLUME_ENVELOPE
+	call Audio3_GetRegisterPointer
+	ld a, $8 ; fade in sound
 	ld [hli], a
 	inc hl
-	ld a, $80
+	ld a, $80 ; restart sound
 	ld [hl], a
-.quit
+.done
 	ret
 .notRest
 	swap a
-	ld b, $0
+	ld b, 0
 	ld hl, wChannelOctaves
 	add hl, bc
 	ld b, [hl]
-	call Audio3_7d8cc
-	ld b, $0
+	call Audio3_CalculateFrequency
+	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 4, [hl]
-	jr z, .asm_7d62c
-	call Audio3_7d803
-.asm_7d62c
+	bit BIT_PITCH_SLIDE_ON, [hl]
+	jr z, .skipPitchSlide
+	call Audio3_InitPitchSlideVars
+.skipPitchSlide
 	push de
 	ld a, c
 	cp Ch5
-	jr nc, .skip ; if sfx Channel
+	jr nc, .sfxChannel ; if sfx channel
+; If this isn't an SFX channel, try the corresponding SFX channel.
 	ld hl, wChannelSoundIDs + Ch5
-	ld d, $0
+	ld d, 0
 	ld e, a
 	add hl, de
 	ld a, [hl]
 	and a
-	jr nz, .done
-	jr .skip
-.done
+	jr nz, .noSfx
+	jr .sfxChannel
+.noSfx
 	pop de
 	ret
-.skip
-	ld b, $0
+.sfxChannel
+	ld b, 0
 	ld hl, wChannelVolumes
 	add hl, bc
 	ld d, [hl]
-	ld b, $2
-	call Audio3_7d8ac
+	ld b, REG_VOLUME_ENVELOPE
+	call Audio3_GetRegisterPointer
 	ld [hl], d
-	call Audio3_7d69d
-	call Audio3_7d66c
+	call Audio3_ApplyDutyCycleAndSoundLength
+	call Audio3_EnableChannelOutput
 	pop de
 	ld b, $0
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 0, [hl]   ; has toggleperfectpitch been used?
-	jr z, .skip2
-	inc e         ; if yes, increment the pitch by 1
-	jr nc, .skip2
+	bit BIT_PERFECT_PITCH, [hl] ; has toggle_perfect_pitch been used?
+	jr z, .skipFrequencyInc
+	inc e                       ; if yes, increment the frequency by 1
+	jr nc, .skipFrequencyInc
 	inc d
-.skip2
+.skipFrequencyInc
 	ld hl, wChannelFrequencyLowBytes
 	add hl, bc
 	ld [hl], e
-	call Audio3_7d6bf
+	call Audio3_ApplyWavePatternAndFrequency
 	ret
 
-Audio3_7d66c:
-	ld b, $0
-	ld hl, Unknown_7db9b
+Audio3_EnableChannelOutput:
+	ld b, 0
+	ld hl, Audio3_HWChannelEnableMasks
 	add hl, bc
 	ld a, [rNR51]
-	or [hl]
+	or [hl] ; set this channel's bits
 	ld d, a
 	ld a, c
 	cp Ch8
-	jr z, .sfxNoiseChannel
+	jr z, .noiseChannelOrNoSfx
 	cp Ch5
 	jr nc, .skip ; if sfx channel
+; If this isn't an SFX channel, try the corresponding SFX channel.
 	ld hl, wChannelSoundIDs + Ch5
 	add hl, bc
 	ld a, [hl]
 	and a
 	jr nz, .skip
-.sfxNoiseChannel
+.noiseChannelOrNoSfx
+; If this is the SFX noise channel or a music channel whose corresponding
+; SFX channel is off, apply stereo panning.
 	ld a, [wStereoPanning]
-	ld hl, Unknown_7db9b
+	ld hl, Audio3_HWChannelEnableMasks
 	add hl, bc
 	and [hl]
 	ld d, a
 	ld a, [rNR51]
-	ld hl, Unknown_7db93
+	ld hl, Audio3_HWChannelDisableMasks
 	add hl, bc
-	and [hl]
-	or d
+	and [hl] ; reset this channel's output bits
+	or d ; set this channel's output bits that enabled in [wStereoPanning]
 	ld d, a
 .skip
 	ld a, d
@@ -842,47 +877,48 @@
 	ld [rNR51], a
 	ret
 
-Audio3_7d69d:
-	ld b, $0
-	ld hl, wChannelNoteDelayCounters
+Audio3_ApplyDutyCycleAndSoundLength:
+	ld b, 0
+	ld hl, wChannelNoteDelayCounters ; use the note delay as sound length
 	add hl, bc
 	ld d, [hl]
 	ld a, c
 	cp Ch3
-	jr z, .channel3 ; if music channel 3
+	jr z, .skipDuty ; if music channel 3
 	cp Ch7
-	jr z, .channel3 ; if sfx channel 3
+	jr z, .skipDuty ; if sfx channel 3
+; include duty cycle (except on channel 3 which doesn't have it)
 	ld a, d
 	and $3f
 	ld d, a
-	ld hl, wChannelDuties
+	ld hl, wChannelDutyCycles
 	add hl, bc
 	ld a, [hl]
 	or d
 	ld d, a
-.channel3
-	ld b, $1
-	call Audio3_7d8ac
+.skipDuty
+	ld b, REG_DUTY_SOUND_LEN
+	call Audio3_GetRegisterPointer
 	ld [hl], d
 	ret
 
-Audio3_7d6bf:
+Audio3_ApplyWavePatternAndFrequency:
 	ld a, c
 	cp Ch3
 	jr z, .channel3
 	cp Ch7
-	jr nz, .notSfxChannel3
+	jr nz, .notChannel3
 	; fall through
 .channel3
 	push de
 	ld de, wMusicWaveInstrument
 	cp Ch3
-	jr z, .musicChannel3
+	jr z, .next
 	ld de, wSfxWaveInstrument
-.musicChannel3
+.next
 	ld a, [de]
 	add a
-	ld d, $0
+	ld d, 0
 	ld e, a
 	ld hl, Audio3_WavePointers
 	add hl, de
@@ -889,9 +925,9 @@
 	ld e, [hl]
 	inc hl
 	ld d, [hl]
-	ld hl, $ff30
+	ld hl, $ff30 ; wave pattern RAM
 	ld b, $f
-	ld a, $0
+	ld a, $0 ; stop hardware channel 3
 	ld [rNR30], a
 .loop
 	ld a, [de]
@@ -901,111 +937,114 @@
 	dec b
 	and a
 	jr nz, .loop
-	ld a, $80
+	ld a, $80 ; start hardware channel 3
 	ld [rNR30], a
 	pop de
-.notSfxChannel3
+.notChannel3
 	ld a, d
-	or $80
-	and $c7
+	or $80 ; use counter mode (i.e. disable output when the counter reaches 0)
+	and $c7 ; zero the unused bits in the register
 	ld d, a
-	ld b, $3
-	call Audio3_7d8ac
-	ld [hl], e
+	ld b, REG_FREQUENCY_LO
+	call Audio3_GetRegisterPointer
+	ld [hl], e ; store frequency low byte
 	inc hl
-	ld [hl], d
-	call Audio3_7d729
+	ld [hl], d ; store frequency high byte
+	call Audio3_ApplyFrequencyModifier
 	ret
 
-Audio3_7d707:
-	call Audio3_7d759
-	jr nc, .asm_7d71f
-	ld d, $0
+Audio3_SetSfxTempo:
+	call Audio3_IsCry
+	jr nc, .notCry
+	ld d, 0
 	ld a, [wTempoModifier]
 	add $80
-	jr nc, .asm_7d716
+	jr nc, .next
 	inc d
-.asm_7d716
+.next
 	ld [wSfxTempo + 1], a
 	ld a, d
 	ld [wSfxTempo], a
-	jr .asm_7d728
-.asm_7d71f
+	jr .done
+.notCry
 	xor a
 	ld [wSfxTempo + 1], a
 	ld a, $1
 	ld [wSfxTempo], a
-.asm_7d728
+.done
 	ret
 
-Audio3_7d729:
-	call Audio3_7d759
-	jr nc, .asm_7d73a
+Audio3_ApplyFrequencyModifier:
+	call Audio3_IsCry
+	jr nc, .done
+; if playing a cry, add the cry's frequency modifier
 	ld a, [wFrequencyModifier]
 	add e
-	jr nc, .asm_7d735
+	jr nc, .noCarry
 	inc d
-.asm_7d735
+.noCarry
 	dec hl
 	ld e, a
 	ld [hl], e
 	inc hl
 	ld [hl], d
-.asm_7d73a
+.done
 	ret
 
-Audio3_7d73b:
-	call Audio3_7d759
-	jr nc, .asm_7d756
+Audio3_GoBackOneCommandIfCry:
+	call Audio3_IsCry
+	jr nc, .done
 	ld hl, wChannelCommandPointers
 	ld e, c
-	ld d, $0
+	ld d, 0
 	sla e
 	rl d
 	add hl, de
 	ld a, [hl]
-	sub $1
+	sub 1
 	ld [hl], a
 	inc hl
 	ld a, [hl]
-	sbc $0
+	sbc 0
 	ld [hl], a
 	scf
 	ret
-.asm_7d756
+.done
 	scf
 	ccf
 	ret
 
-Audio3_7d759:
+Audio3_IsCry:
+; Returns whether the currently playing audio is a cry in carry.
 	ld a, [wChannelSoundIDs + Ch5]
-	cp $14
-	jr nc, .asm_7d762
-	jr .asm_7d768
-.asm_7d762
-	cp $86
-	jr z, .asm_7d768
-	jr c, .asm_7d76b
-.asm_7d768
+	cp CRY_SFX_START
+	jr nc, .next
+	jr .no
+.next
+	cp CRY_SFX_END
+	jr z, .no
+	jr c, .yes
+.no
 	scf
 	ccf
 	ret
-.asm_7d76b
+.yes
 	scf
 	ret
 
-Audio3_ApplyPitchBend:
+Audio3_ApplyPitchSlide:
 	ld hl, wChannelFlags1
 	add hl, bc
-	bit 5, [hl]
-	jp nz, .asm_7d7b4
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	bit BIT_PITCH_SLIDE_DECREASING, [hl]
+	jp nz, .frequencyDecreasing
+; frequency increasing
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld e, [hl]
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld d, [hl]
-	ld hl, wChannelPitchBendFrequencySteps
+	ld hl, wChannelPitchSlideFrequencySteps
 	add hl, bc
 	ld l, [hl]
 	ld h, b
@@ -1012,41 +1051,41 @@
 	add hl, de
 	ld d, h
 	ld e, l
-	ld hl, wChannelPitchBendCurrentFrequencyFractionalPart
+	ld hl, wChannelPitchSlideCurrentFrequencyFractionalPart
 	add hl, bc
 	push hl
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
 	add hl, bc
 	ld a, [hl]
 	pop hl
 	add [hl]
 	ld [hl], a
-	ld a, $0
+	ld a, 0
 	adc e
 	ld e, a
-	ld a, $0
+	ld a, 0
 	adc d
 	ld d, a
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
 	ld a, [hl]
 	cp d
-	jp c, .asm_7d7fa
-	jr nz, .asm_7d7e7
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	jp c, .reachedTargetFrequency
+	jr nz, .applyUpdatedFrequency
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
 	ld a, [hl]
 	cp e
-	jp c, .asm_7d7fa
-	jr .asm_7d7e7
-.asm_7d7b4
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	jp c, .reachedTargetFrequency
+	jr .applyUpdatedFrequency
+.frequencyDecreasing
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld a, [hl]
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld d, [hl]
-	ld hl, wChannelPitchBendFrequencySteps
+	ld hl, wChannelPitchSlideFrequencySteps
 	add hl, bc
 	ld e, [hl]
 	sub e
@@ -1054,7 +1093,7 @@
 	ld a, d
 	sbc b
 	ld d, a
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
 	add hl, bc
 	ld a, [hl]
 	add a
@@ -1065,55 +1104,56 @@
 	ld a, d
 	sbc b
 	ld d, a
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
 	ld a, d
 	cp [hl]
-	jr c, .asm_7d7fa
-	jr nz, .asm_7d7e7
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	jr c, .reachedTargetFrequency
+	jr nz, .applyUpdatedFrequency
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
 	ld a, e
 	cp [hl]
-	jr c, .asm_7d7fa
-.asm_7d7e7
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	jr c, .reachedTargetFrequency
+.applyUpdatedFrequency
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld [hl], e
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld [hl], d
-	ld b, $3
-	call Audio3_7d8ac
+	ld b, REG_FREQUENCY_LO
+	call Audio3_GetRegisterPointer
 	ld a, e
 	ld [hli], a
 	ld [hl], d
 	ret
-.asm_7d7fa
+.reachedTargetFrequency
+; Turn off pitch slide when the target frequency has been reached.
 	ld hl, wChannelFlags1
 	add hl, bc
-	res 4, [hl]
-	res 5, [hl]
+	res BIT_PITCH_SLIDE_ON, [hl]
+	res BIT_PITCH_SLIDE_DECREASING, [hl]
 	ret
 
-Audio3_7d803:
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+Audio3_InitPitchSlideVars:
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld [hl], d
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld [hl], e
 	ld hl, wChannelNoteDelayCounters
 	add hl, bc
 	ld a, [hl]
-	ld hl, wChannelPitchBendLengthModifiers
+	ld hl, wChannelPitchSlideLengthModifiers
 	add hl, bc
 	sub [hl]
-	jr nc, .asm_7d81b
-	ld a, $1
-.asm_7d81b
+	jr nc, .next
+	ld a, 1
+.next
 	ld [hl], a
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
 	ld a, e
 	sub [hl]
@@ -1120,74 +1160,84 @@
 	ld e, a
 	ld a, d
 	sbc b
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
 	sub [hl]
-	jr c, .asm_7d837
+	jr c, .targetFrequencyGreater
 	ld d, a
-	ld b, $0
+	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	set 5, [hl]
-	jr .asm_7d85a
-.asm_7d837
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	set BIT_PITCH_SLIDE_DECREASING, [hl]
+	jr .next2
+.targetFrequencyGreater
+; If the target frequency is greater, subtract the current frequency from
+; the target frequency to get the absolute difference.
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, bc
 	ld d, [hl]
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, bc
 	ld e, [hl]
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, bc
 	ld a, [hl]
 	sub e
 	ld e, a
+
+; Bug. Instead of borrowing from the high byte of the target frequency as it
+; should, it borrows from the high byte of the current frequency instead.
+; This means that the result will be 0x200 greater than it should be if the
+; low byte of the current frequency is greater than the low byte of the
+; target frequency.
 	ld a, d
 	sbc b
 	ld d, a
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, bc
 	ld a, [hl]
 	sub d
 	ld d, a
-	ld b, $0
+	ld b, 0
 	ld hl, wChannelFlags1
 	add hl, bc
-	res 5, [hl]
-.asm_7d85a
-	ld hl, wChannelPitchBendLengthModifiers
+	res BIT_PITCH_SLIDE_DECREASING, [hl]
+
+.next2
+	ld hl, wChannelPitchSlideLengthModifiers
 	add hl, bc
-.asm_7d85e
+.divideLoop
 	inc b
 	ld a, e
 	sub [hl]
 	ld e, a
-	jr nc, .asm_7d85e
+	jr nc, .divideLoop
 	ld a, d
 	and a
-	jr z, .asm_7d86c
+	jr z, .doneDividing
 	dec a
 	ld d, a
-	jr .asm_7d85e
-.asm_7d86c
-	ld a, e
+	jr .divideLoop
+.doneDividing
+	ld a, e ; a = remainder - dividend
 	add [hl]
-	ld d, b
-	ld b, $0
-	ld hl, wChannelPitchBendFrequencySteps
+	ld d, b ; d = quotient + 1
+	ld b, 0
+	ld hl, wChannelPitchSlideFrequencySteps
 	add hl, bc
-	ld [hl], d
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
+	ld [hl], d ; store quotient + 1
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
 	add hl, bc
-	ld [hl], a
-	ld hl, wChannelPitchBendCurrentFrequencyFractionalPart
+	ld [hl], a ; store remainder - dividend
+	ld hl, wChannelPitchSlideCurrentFrequencyFractionalPart
 	add hl, bc
-	ld [hl], a
+	ld [hl], a ; store remainder - dividend
 	ret
 
-Audio3_ApplyDutyCycle:
-	ld b, $0
-	ld hl, wChannelDutyCycles
+Audio3_ApplyDutyCyclePattern:
+	ld b, 0
+	ld hl, wChannelDutyCyclePatterns
 	add hl, bc
 	ld a, [hl]
 	rlca
@@ -1195,8 +1245,8 @@
 	ld [hl], a
 	and $c0
 	ld d, a
-	ld b, $1
-	call Audio3_7d8ac
+	ld b, REG_DUTY_SOUND_LEN
+	call Audio3_GetRegisterPointer
 	ld a, [hl]
 	and $3f
 	or d
@@ -1204,7 +1254,7 @@
 	ret
 
 Audio3_GetNextMusicByte:
-	ld d, $0
+	ld d, 0
 	ld a, c
 	add a
 	ld e, a
@@ -1221,9 +1271,10 @@
 	ld [hl], d
 	ret
 
-Audio3_7d8ac:
+Audio3_GetRegisterPointer:
+; hl = address of hardware sound register b for software channel c
 	ld a, c
-	ld hl, Unknown_7db8b
+	ld hl, Audio3_HWChannelBaseAddresses
 	add l
 	jr nc, .noCarry
 	inc h
@@ -1235,13 +1286,14 @@
 	ld h, $ff
 	ret
 
-Audio3_7d8bb:
-	ld h, $0
+Audio3_MultiplyAdd:
+; hl = l + (a * de)
+	ld h, 0
 .loop
 	srl a
-	jr nc, .noCarry
+	jr nc, .skipAdd
 	add hl, de
-.noCarry
+.skipAdd
 	sla e
 	rl d
 	and a
@@ -1250,8 +1302,9 @@
 .done
 	ret
 
-Audio3_7d8cc:
-	ld h, $0
+Audio3_CalculateFrequency:
+; return the frequency for note a, octave b in de
+	ld h, 0
 	ld l, a
 	add hl, hl
 	ld d, h
@@ -1263,7 +1316,7 @@
 	ld d, [hl]
 	ld a, b
 .loop
-	cp $7
+	cp 7
 	jr z, .done
 	sra d
 	rr e
@@ -1270,7 +1323,7 @@
 	inc a
 	jr .loop
 .done
-	ld a, $8
+	ld a, 8
 	add d
 	ld d, a
 	ret
@@ -1278,14 +1331,15 @@
 Audio3_PlaySound::
 	ld [wSoundID], a
 	cp $ff
-	jp z, Audio3_7daa8
-	cp $c2
-	jp z, Audio3_7d9c2
-	jp c, Audio3_7d9c2
+	jp z, .stopAllAudio
+	cp MAX_SFX_ID_3
+	jp z, .playSfx
+	jp c, .playSfx
 	cp $fe
-	jr z, .asm_7d901
-	jp nc, Audio3_7d9c2
-.asm_7d901
+	jr z, .playMusic
+	jp nc, .playSfx
+
+.playMusic
 	xor a
 	ld [wUnusedC000], a
 	ld [wDisableChannelOutputWhenSfxEnds], a
@@ -1294,53 +1348,53 @@
 	ld [wSfxWaveInstrument], a
 	ld d, $8
 	ld hl, wChannelReturnAddresses
-	call FillAudioRAM3
+	call .FillMem
 	ld hl, wChannelCommandPointers
-	call FillAudioRAM3
+	call .FillMem
 	ld d, $4
 	ld hl, wChannelSoundIDs
-	call FillAudioRAM3
+	call .FillMem
 	ld hl, wChannelFlags1
-	call FillAudioRAM3
-	ld hl, wChannelDuties
-	call FillAudioRAM3
+	call .FillMem
 	ld hl, wChannelDutyCycles
-	call FillAudioRAM3
+	call .FillMem
+	ld hl, wChannelDutyCyclePatterns
+	call .FillMem
 	ld hl, wChannelVibratoDelayCounters
-	call FillAudioRAM3
+	call .FillMem
 	ld hl, wChannelVibratoExtents
-	call FillAudioRAM3
+	call .FillMem
 	ld hl, wChannelVibratoRates
-	call FillAudioRAM3
+	call .FillMem
 	ld hl, wChannelFrequencyLowBytes
-	call FillAudioRAM3
+	call .FillMem
 	ld hl, wChannelVibratoDelayCounterReloadValues
-	call FillAudioRAM3
+	call .FillMem
 	ld hl, wChannelFlags2
-	call FillAudioRAM3
-	ld hl, wChannelPitchBendLengthModifiers
-	call FillAudioRAM3
-	ld hl, wChannelPitchBendFrequencySteps
-	call FillAudioRAM3
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
-	call FillAudioRAM3
-	ld hl, wChannelPitchBendCurrentFrequencyFractionalPart
-	call FillAudioRAM3
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
-	call FillAudioRAM3
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
-	call FillAudioRAM3
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
-	call FillAudioRAM3
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
-	call FillAudioRAM3
+	call .FillMem
+	ld hl, wChannelPitchSlideLengthModifiers
+	call .FillMem
+	ld hl, wChannelPitchSlideFrequencySteps
+	call .FillMem
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
+	call .FillMem
+	ld hl, wChannelPitchSlideCurrentFrequencyFractionalPart
+	call .FillMem
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
+	call .FillMem
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
+	call .FillMem
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
+	call .FillMem
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
+	call .FillMem
 	ld a, $1
 	ld hl, wChannelLoopCounters
-	call FillAudioRAM3
+	call .FillMem
 	ld hl, wChannelNoteDelayCounters
-	call FillAudioRAM3
+	call .FillMem
 	ld hl, wChannelNoteSpeeds
-	call FillAudioRAM3
+	call .FillMem
 	ld [wMusicTempo], a
 	ld a, $ff
 	ld [wStereoPanning], a
@@ -1348,7 +1402,7 @@
 	ld [rNR50], a
 	ld a, $8
 	ld [rNR10], a
-	ld a, $0
+	ld a, 0
 	ld [rNR51], a
 	xor a
 	ld [rNR30], a
@@ -1356,12 +1410,12 @@
 	ld [rNR30], a
 	ld a, $77
 	ld [rNR50], a
-	jp Audio3_7db03
+	jp .playSoundCommon
 
-Audio3_7d9c2:
+.playSfx
 	ld l, a
 	ld e, a
-	ld h, $0
+	ld h, 0
 	ld d, h
 	add hl, hl
 	add hl, de
@@ -1376,13 +1430,13 @@
 	rlca
 	rlca
 	ld c, a
-.asm_7d9db
+.sfxChannelLoop
 	ld d, c
 	ld a, c
 	add a
 	add c
 	ld c, a
-	ld b, $0
+	ld b, 0
 	ld a, [wSfxHeaderPointer]
 	ld h, a
 	ld a, [wSfxHeaderPointer + 1]
@@ -1391,32 +1445,32 @@
 	ld c, d
 	ld a, [hl]
 	and $f
-	ld e, a
-	ld d, $0
+	ld e, a ; software channel ID
+	ld d, 0
 	ld hl, wChannelSoundIDs
 	add hl, de
 	ld a, [hl]
 	and a
-	jr z, .asm_7da17
+	jr z, .playChannel
 	ld a, e
-	cp $7
-	jr nz, .asm_7da0e
+	cp Ch8
+	jr nz, .notNoiseChannel
 	ld a, [wSoundID]
-	cp $14
-	jr nc, .asm_7da07
+	cp NOISE_INSTRUMENTS_END
+	jr nc, .notNoiseInstrument
 	ret
-.asm_7da07
+.notNoiseInstrument
 	ld a, [hl]
-	cp $14
-	jr z, .asm_7da17
-	jr c, .asm_7da17
-.asm_7da0e
+	cp NOISE_INSTRUMENTS_END
+	jr z, .playChannel
+	jr c, .playChannel
+.notNoiseChannel
 	ld a, [wSoundID]
 	cp [hl]
-	jr z, .asm_7da17
-	jr c, .asm_7da17
+	jr z, .playChannel
+	jr c, .playChannel
 	ret
-.asm_7da17
+.playChannel
 	xor a
 	push de
 	ld h, d
@@ -1439,10 +1493,10 @@
 	ld hl, wChannelFlags1
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelDuties
+	ld hl, wChannelDutyCycles
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelDutyCycles
+	ld hl, wChannelDutyCyclePatterns
 	add hl, de
 	ld [hl], a
 	ld hl, wChannelVibratoDelayCounters
@@ -1460,28 +1514,28 @@
 	ld hl, wChannelVibratoDelayCounterReloadValues
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendLengthModifiers
+	ld hl, wChannelPitchSlideLengthModifiers
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendFrequencySteps
+	ld hl, wChannelPitchSlideFrequencySteps
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendFrequencyStepsFractionalPart
+	ld hl, wChannelPitchSlideFrequencyStepsFractionalPart
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendCurrentFrequencyFractionalPart
+	ld hl, wChannelPitchSlideCurrentFrequencyFractionalPart
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendCurrentFrequencyHighBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyHighBytes
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendCurrentFrequencyLowBytes
+	ld hl, wChannelPitchSlideCurrentFrequencyLowBytes
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendTargetFrequencyHighBytes
+	ld hl, wChannelPitchSlideTargetFrequencyHighBytes
 	add hl, de
 	ld [hl], a
-	ld hl, wChannelPitchBendTargetFrequencyLowBytes
+	ld hl, wChannelPitchSlideTargetFrequencyLowBytes
 	add hl, de
 	ld [hl], a
 	ld hl, wChannelFlags2
@@ -1498,35 +1552,35 @@
 	add hl, de
 	ld [hl], a
 	ld a, e
-	cp $4
-	jr nz, .asm_7da9f
+	cp Ch5
+	jr nz, .skipSweepDisable
 	ld a, $8
-	ld [rNR10], a
-.asm_7da9f
+	ld [rNR10], a ; sweep off
+.skipSweepDisable
 	ld a, c
 	and a
-	jp z, Audio3_7db03
+	jp z, .playSoundCommon
 	dec c
-	jp .asm_7d9db
+	jp .sfxChannelLoop
 
-Audio3_7daa8:
+.stopAllAudio
 	ld a, $80
-	ld [rNR52], a
-	ld [rNR30], a
+	ld [rNR52], a ; sound hardware on
+	ld [rNR30], a ; wave playback on
 	xor a
-	ld [rNR51], a
-	ld [rNR32], a
+	ld [rNR51], a ; no sound output
+	ld [rNR32], a ; mute channel 3 (wave channel)
 	ld a, $8
-	ld [rNR10], a
-	ld [rNR12], a
-	ld [rNR22], a
-	ld [rNR42], a
+	ld [rNR10], a ; sweep off
+	ld [rNR12], a ; mute channel 1 (pulse channel 1)
+	ld [rNR22], a ; mute channel 2 (pulse channel 2)
+	ld [rNR42], a ; mute channel 4 (noise channel)
 	ld a, $40
-	ld [rNR14], a
+	ld [rNR14], a ; counter mode
 	ld [rNR24], a
 	ld [rNR44], a
 	ld a, $77
-	ld [rNR50], a
+	ld [rNR50], a ; full volume
 	xor a
 	ld [wUnusedC000], a
 	ld [wDisableChannelOutputWhenSfxEnds], a
@@ -1537,11 +1591,11 @@
 	ld [wSfxWaveInstrument], a
 	ld d, $a0
 	ld hl, wChannelCommandPointers
-	call FillAudioRAM3
+	call .FillMem
 	ld a, $1
 	ld d, $18
 	ld hl, wChannelNoteDelayCounters
-	call FillAudioRAM3
+	call .FillMem
 	ld [wMusicTempo], a
 	ld [wSfxTempo], a
 	ld a, $ff
@@ -1549,7 +1603,7 @@
 	ret
 
 ; fills d bytes at hl with a
-FillAudioRAM3:
+.FillMem
 	ld b, d
 .loop
 	ld [hli], a
@@ -1557,11 +1611,11 @@
 	jr nz, .loop
 	ret
 
-Audio3_7db03:
+.playSoundCommon
 	ld a, [wSoundID]
 	ld l, a
 	ld e, a
-	ld h, $0
+	ld h, 0
 	ld d, h
 	add hl, hl
 	add hl, de
@@ -1581,19 +1635,19 @@
 	ld b, c
 	inc b
 	inc de
-	ld c, $0
-.asm_7db25
+	ld c, 0
+.commandPointerLoop
 	cp c
-	jr z, .asm_7db2d
+	jr z, .next
 	inc c
 	inc hl
 	inc hl
-	jr .asm_7db25
-.asm_7db2d
+	jr .commandPointerLoop
+.next
 	push hl
 	push bc
 	push af
-	ld b, $0
+	ld b, 0
 	ld c, a
 	ld hl, wChannelSoundIDs
 	add hl, bc
@@ -1600,12 +1654,12 @@
 	ld a, [wSoundID]
 	ld [hl], a
 	pop af
-	cp $3
-	jr c, .asm_7db46
+	cp Ch4
+	jr c, .skipSettingFlag
 	ld hl, wChannelFlags1
 	add hl, bc
-	set 2, [hl]
-.asm_7db46
+	set BIT_NOISE_OR_SFX, [hl]
+.skipSettingFlag
 	pop bc
 	pop hl
 	ld a, [de] ; get channel pointer
@@ -1620,52 +1674,53 @@
 	and a
 	ld a, [de]
 	inc de
-	jr nz, .asm_7db25
+	jr nz, .commandPointerLoop
 	ld a, [wSoundID]
-	cp $14
-	jr nc, .asm_7db5f
-	jr .asm_7db89
-.asm_7db5f
+	cp CRY_SFX_START
+	jr nc, .maybeCry
+	jr .done
+.maybeCry
 	ld a, [wSoundID]
-	cp $86
-	jr z, .asm_7db89
-	jr c, .asm_7db6a
-	jr .asm_7db89
-.asm_7db6a
+	cp CRY_SFX_END
+	jr z, .done
+	jr c, .cry
+	jr .done
+.cry
 	ld hl, wChannelSoundIDs + Ch5
 	ld [hli], a
 	ld [hli], a
 	ld [hli], a
 	ld [hl], a
-	ld hl, wChannelCommandPointers + Ch7 * 2 ; sfx noise channel pointer
-	ld de, Noise3_endchannel
+	ld hl, wChannelCommandPointers + Ch7 * 2 ; sfx wave channel pointer
+	ld de, Audio3_CryRet
 	ld [hl], e
 	inc hl
-	ld [hl], d ; overwrite pointer to point to endchannel
+	ld [hl], d ; overwrite pointer to point to sound_ret
 	ld a, [wSavedVolume]
 	and a
-	jr nz, .asm_7db89
+	jr nz, .done
 	ld a, [rNR50]
 	ld [wSavedVolume], a
 	ld a, $77
-	ld [rNR50], a
-.asm_7db89
+	ld [rNR50], a ; full volume
+.done
 	ret
 
-Noise3_endchannel:
+Audio3_CryRet:
 	sound_ret
 
-Unknown_7db8b:
-	db $10, $15, $1A, $1F ; channels 0-3
-	db $10, $15, $1A, $1F ; channels 4-7
+Audio3_HWChannelBaseAddresses:
+; the low bytes of each HW channel's base address
+	db HW_CH1_BASE, HW_CH2_BASE, HW_CH3_BASE, HW_CH4_BASE ; channels 0-3
+	db HW_CH1_BASE, HW_CH2_BASE, HW_CH3_BASE, HW_CH4_BASE ; channels 4-7
 
-Unknown_7db93:
-	db $EE, $DD, $BB, $77 ; channels 0-3
-	db $EE, $DD, $BB, $77 ; channels 4-7
+Audio3_HWChannelDisableMasks:
+	db HW_CH1_DISABLE_MASK, HW_CH2_DISABLE_MASK, HW_CH3_DISABLE_MASK, HW_CH4_DISABLE_MASK ; channels 0-3
+	db HW_CH1_DISABLE_MASK, HW_CH2_DISABLE_MASK, HW_CH3_DISABLE_MASK, HW_CH4_DISABLE_MASK ; channels 4-7
 
-Unknown_7db9b:
-	db $11, $22, $44, $88 ; channels 0-3
-	db $11, $22, $44, $88 ; channels 4-7
+Audio3_HWChannelEnableMasks:
+	db HW_CH1_ENABLE_MASK, HW_CH2_ENABLE_MASK, HW_CH3_ENABLE_MASK, HW_CH4_ENABLE_MASK ; channels 0-3
+	db HW_CH1_ENABLE_MASK, HW_CH2_ENABLE_MASK, HW_CH3_ENABLE_MASK, HW_CH4_ENABLE_MASK ; channels 4-7
 
 Audio3_Pitches:
 	dw $F82C ; C_
@@ -1680,5 +1735,3 @@
 	dw $FB58 ; A_
 	dw $FB9B ; A#
 	dw $FBDA ; B_
-
-
--- a/audio/music/yellow/meetjessiejames.asm
+++ b/audio/music/yellow/meetjessiejames.asm
@@ -306,4 +306,3 @@
 	note E_, 1
 	rest 1
 	sound_loop 0, Music_MeetJessieJames_branch_83235
-	sound_ret
--- a/constants/music_constants.asm
+++ b/constants/music_constants.asm
@@ -20,19 +20,27 @@
 REG_VOLUME_ENVELOPE EQU 2
 REG_FREQUENCY_LO    EQU 3
 
-MAX_SFX_ID EQU $B9
+MAX_SFX_ID_1 EQUS "SFX_SAFARI_ZONE_PA"
+MAX_SFX_ID_2 EQUS "SFX_SILPH_SCOPE"
+MAX_SFX_ID_3 EQUS "SFX_SHOOTING_STAR"
 
-CRY_SFX_START EQU $14
-CRY_SFX_END   EQU $86
+NOISE_INSTRUMENTS_START EQUS "SFX_NOISE_INSTRUMENT01"
+NOISE_INSTRUMENTS_END   EQUS "SFX_NOISE_INSTRUMENT19 + 1"
 
+CRY_SFX_START EQUS "SFX_CRY_00"
+CRY_SFX_END   EQUS "SFX_CRY_25 + 3"
+
+BATTLE_SFX_START EQUS "SFX_PECK"
+BATTLE_SFX_END   EQUS "SFX_SILPH_SCOPE + 1"
+
 ; wChannelFlags1 constants
-BIT_PERFECT_PITCH         EQU 0 ; controlled by toggleperfectpitch command
-BIT_CHANNEL_CALL          EQU 1 ; if in channel call
-BIT_NOISE_OR_SFX          EQU 2 ; if channel is the music noise channel or an SFX channel
-BIT_VIBRATO_DIRECTION     EQU 3 ; if the pitch is above or below normal (cycles)
-BIT_PITCH_BEND_ON         EQU 4 ; if pitch bend is active
-BIT_PITCH_BEND_DECREASING EQU 5 ; if the pitch bend frequency is decreasing (instead of increasing)
-BIT_ROTATE_DUTY           EQU 6 ; if rotating duty
+BIT_PERFECT_PITCH          EQU 0 ; controlled by toggle_perfect_pitch command
+BIT_SOUND_CALL             EQU 1 ; if in sound call
+BIT_NOISE_OR_SFX           EQU 2 ; if channel is the music noise channel or an SFX channel
+BIT_VIBRATO_DIRECTION      EQU 3 ; if the pitch is above or below normal (cycles)
+BIT_PITCH_SLIDE_ON         EQU 4 ; if pitch slide is active
+BIT_PITCH_SLIDE_DECREASING EQU 5 ; if the pitch slide frequency is decreasing (instead of increasing)
+BIT_ROTATE_DUTY_CYCLE      EQU 6 ; if rotating duty cycle
 
 ; wChannelFlags2 constant (only has one flag)
 BIT_EXECUTE_MUSIC EQU 0 ; if in execute music
--- a/macros/audio_macros.asm
+++ b/macros/audio_macros.asm
@@ -86,6 +86,14 @@
 	db \1
 ENDM
 
+;format: instrument [1, 3-10], length (in 16ths)
+; like dnote but one 1 byte instead of 2
+; can only be used with instruments 1-10, excluding 2
+; unused
+dnote_short: MACRO
+	db (\1 << 4) | (\2 - 1)
+ENDM
+
 ;format: length (in 16ths)
 rest: MACRO
 	db $C0 | (\1 - 1)
--- a/wram.asm
+++ b/wram.asm
@@ -101,10 +101,10 @@
 wChannelFlags2:: ; c036
 	ds 8
 
-wChannelDuties:: ; c03e
+wChannelDutyCycles:: ; c03e
 	ds 8
 
-wChannelDutyCycles:: ; c046
+wChannelDutyCyclePatterns:: ; c046
 	ds 8
 
 wChannelVibratoDelayCounters:: ; c04e
@@ -126,28 +126,28 @@
 ; delay of the beginning of the vibrato from the start of the note
 	ds 8
 
-wChannelPitchBendLengthModifiers:: ; c076
+wChannelPitchSlideLengthModifiers:: ; c076
 	ds 8
 
-wChannelPitchBendFrequencySteps:: ; c07e
+wChannelPitchSlideFrequencySteps:: ; c07e
 	ds 8
 
-wChannelPitchBendFrequencyStepsFractionalPart:: ; c086
+wChannelPitchSlideFrequencyStepsFractionalPart:: ; c086
 	ds 8
 
-wChannelPitchBendCurrentFrequencyFractionalPart:: ; c08e
+wChannelPitchSlideCurrentFrequencyFractionalPart:: ; c08e
 	ds 8
 
-wChannelPitchBendCurrentFrequencyHighBytes:: ; c096
+wChannelPitchSlideCurrentFrequencyHighBytes:: ; c096
 	ds 8
 
-wChannelPitchBendCurrentFrequencyLowBytes:: ; c09e
+wChannelPitchSlideCurrentFrequencyLowBytes:: ; c09e
 	ds 8
 
-wChannelPitchBendTargetFrequencyHighBytes:: ; c0a6
+wChannelPitchSlideTargetFrequencyHighBytes:: ; c0a6
 	ds 8
 
-wChannelPitchBendTargetFrequencyLowBytes:: ; c0ae
+wChannelPitchSlideTargetFrequencyLowBytes:: ; c0ae
 	ds 8
 
 wChannelNoteDelayCounters:: ; c0b6