* _GUS_VOICEFREQ - Sets voice (sample) playback frequency (P1=Hz)
* _GUS_VOICEVOL - Sets voice volume (P1=volume, 0xfff=max, 0xeff=half, 0x000=off)
* _GUS_VOICEVOL2 - Sets voice volume (P1=volume, 0xfff=max, 0xeff=half, 0x000=off)
* _GUS_VOICEFREQ - Sets voice (sample) playback frequency (P1=Hz)
* _GUS_VOICEVOL - Sets voice volume (P1=volume, 0xfff=max, 0xeff=half, 0x000=off)
* _GUS_VOICEVOL2 - Sets voice volume (P1=volume, 0xfff=max, 0xeff=half, 0x000=off)