al_set_voice_playing man page
al_set_voice_playing — Allegro 5 API
#include <allegro5/allegro_audio.h> bool al_set_voice_playing(ALLEGRO_VOICE *voice, bool val)
Change whether a voice is playing or not. This can only work if the voice has a non-streaming object attached to it, e.g. a sample instance. On success the voice's current sample position is reset.
Returns true on success, false on failure.