gus_speaker_ctl
gus_speaker_ctl(sc, vol.left > AUDIO_MIN_GAIN ?
gus_speaker_ctl(sc, cp->un.ord ? SPKR_OFF : SPKR_ON);
gus_speaker_ctl(sc, cp->un.ord ? SPKR_OFF : SPKR_ON);
gus_speaker_ctl(sc, (flags & FWRITE) ? SPKR_ON : SPKR_OFF);
int gus_speaker_ctl(void *, int);