With the voice track shown by clicking the "Facial" button on the timeline for a character you should see the "voice clip" track and your voice clip. The one I imported was named 19446__totya__yeah (see below).

Right click on the voice clip and select "un-group".
This will split the voice clip into two tracks: voice and lips.
These are sub-tracks of the Voice Clip. Click on the arrow to the left of the track header "Voice Clip" to expand.

A character is made up of many "sprites". Some examples would be eyes, ears, hand, arms, etc.
Actually, each of these "sprites" is really a container that holds a single sprite image but is commonly referred to as a "sprite".
CTA provides the ability to have a group (or library) of sprites that a sprite object/container can select from for display.
With the ability to select from this group of images you can switch sprites on the fly throughout your animation.
One of those many "sprites" are the lips.
There a group of sprites for the lips for facial expressions and another group for speaking (see partial list of speaking sprites below).
To get create the look of speaking, the lips sprite is switched between the various sprites from the voice group where each represent various mouth pronunciation positions.

In the "Lips" track each of the black diamonds represents a switching of the lips from one "sprite" to another. When the audio file was imported it was analyzed and the various lip sprites were assigned at different points in the audio track to simulate the character talking. The voice and lips track were then grouped together into a "Voice Clip" and placed on the timeline for that character.
With the Voice Clip un-grouped you can edit the lips track to add, delete, or change the sprites.
Jeff
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