Audible requires a few seconds of room tone at the beginning and end of each file. (myworkfromhomemoney.com)
The most common issues we see include peaks being out of range, and too much / little room tone at the head or tail of audio files. (medium.com)
This is a film of rooms, street corners, and swaths of shadow through which actors move, of room tones in which voices appear and die away. (filmcomment.com)