Everything About the Sound Editor When you double-click on a sound layer in the Timeline view, the Sound Element Editor appears. Mute/Unmute: This button mutes and unmutes the sound layer during the scene play back. Layer Name: This field displays the layer's name. Sound Editor: This button opens the Sound editor. Start Frame/End Frame: These fields determine the start and end frame of the sound file. Detect: This button launches the automated lip-sync detection. Map: This button opens the Map Lip-sync dialog box. Mouth Shapes: This section shows the automated lip-sync detection during the scene play back. Click on the thumbnail image of each mouth to change the phoneme assigned to the current frame.