Allow author to remove "dead-air" from enunciated audio

[burrage]

1.) Allow author to remove any "dead-air" from the beginning and end of enunciated audio so the duration is more true to the actual spoken audio.
OR
2.) Allow author to set the word begin and end times for enunciated audio for the duration.
OR
3.) We may find a tool or webpage that automatically trims all audio in this manner. This will help for file size + fitting better to the highlight duration.