So technically possible, in my opinion. The problem is activating 100 wave files before getting the one you want. User agent could prompt user to load. But audio and video are different. This applies to multi-layered presentations as well.
Every layer needs to be controlled, except the one in the front.
So every supported layer needs control. The user needs to be able to determine what is distracting. So users need to be able to turn off about every layer. An interesting technique would be to present layers adjacent, as thumbnails. I can think of cases, with style sheets, to determine what the background image is.