Sound Playback

Before playing back any sound, click the Enable Sound  button in the Playback toolbar or enable it through the Play menu (in the top menu). This will ensure that you can hear the sound layers in your scene, even the ones included within symbols.

Mute

If there are two or more sound layers and you want to listen to them independently, you can disable the unwanted sound by clicking the Mute Sound  button on the sound name layer in the Timeline view.