If I can work out how to paste an image I will do so.
This morning I opened up an audio-book to inspect it (downloaded from YouTube). There is the usual introduction “This Audio book is published by blah-blah-blah”, then the traveling cursor skips over about one second of wave before continuing " blah-blah-blah …".
No sound is audible to my ears while the little squiggle is traversed.
My first thought is that the skinny waveform is some sorts of Digital Rights Management or a signature to assist in tracking copyright violations.
My second thought is that ANY wave that shows up in Audacity ought to make some kind of noise. I am used to seeing “clicks” and similar Milli-second like sharp peaks.
Without belabouring the issue of Copyright I’d be interested in your comments.