When you were growing up, you might've wondered what all those backward messages were all about on your records, and this might have tempted you to reverse an audio clip. While it may have been cool when you were young, its highly unlikely you want it to happen in your After Effects compositions. If you change the speed or direction of a video clip, its audio file will also change. This may result in the unexpected.
Before changing the speed or direction of a video track that has audio in the comp, you must duplicate the track. Press Cmd+D (Ctrl+D) to duplicate selected tracks.
Turn the visibility icons off on the tracks that have been unaffected by speed changes. These will be your audio only.
To avoid confusion, move your audio only tacks to the bottom of the composition, and lock them to prevent changes in position or visibility.
On tracks that have speed changes applied, disable the audio by clicking on the speaker icon.