snd_gf1_stop_voices
void snd_gf1_stop_voices(struct snd_gus_card * gus, unsigned short v_min, unsigned short v_max);
snd_gf1_stop_voices(gus, voice, voice);
snd_gf1_stop_voices(gus, voice, voice);
snd_gf1_stop_voices(gus, 0, 31); /* stop all voices */