ALLEGRO_VOICE man page

#include <allegro5/allegro_audio.h>

typedef struct ALLEGRO_VOICE ALLEGRO_VOICE;

A voice represents an audio device on the system, which may be a real device, or an abstract device provided by the operating system. To play back audio, you would attach a mixer, sample instance or audio stream to a voice.

ALLEGRO_MIXER(3), ALLEGRO_SAMPLE(3), ALLEGRO_AUDIO_STREAM(3)

ALLEGRO_AUDIO_STREAM(3), ALLEGRO_SAMPLE_INSTANCE(3).