It doesn't seem like a good idea at all for ebooks. People read at different speeds, so how could it tell what particular sentence the reader's eye was at at that moment? What if the reader hears the "patter of footsteps" or the "booming gong" before he reaches that passage in the book?
I don't think I'd like it. However, I LOVE the playlists
Moxie Mezcal has online for her (his??) books. Putting the playlist online is a cool little "extra" thing that readers can check out (or not), and it draws people to the website. I wish more authors would do it.