al_fill_silence - Man Page
Allegro 5 API
#include <allegro5/allegro_audio.h> void al_fill_silence(void *buf, unsigned int samples, ALLEGRO_AUDIO_DEPTH depth, ALLEGRO_CHANNEL_CONF chan_conf)
Fill a buffer with silence, for the given format and channel configuration. The buffer must have enough space for the given number of samples, and be properly aligned.
Allegro reference manual