Can standard bubble wrap etc that furniture comes wrapped in, be used for a sound deadener for speakers, or to stop some rattling inside the boot/trunk or doors ??
Thanks (IMG:style_emoticons/default/smile.gif)

If the bubble wrap is being used to simply stop something from rolling around (or rattling) then I would assume it would work to perform that function as a filler. However if you are trying to dampen sound from coming into your cabin, you should find some other media. Thin plastic not only has very poor sound dampening properties; I would also be inclined to think the plastic would be noisy if it moves around (even if it's just rubbing against itself). For sound dampening you should really consider something that either has some mass to it or something that is very fibrous (insulation).

Also, to understand why a filler is installed in speaker boxes, you need to understand that, commonly, low frequency sound waves will not fully develop (spread out) before they reach your ears. The filler (usually a synthetic insulation) helps fix that problem by letting the sound waves take a longer path (and even bounce around / reflect off the insulation) before the sound waves make their way out of the speaker box. The filler essentially tricks the sound waves into thinking that they are inside a much larger cavity.

BTW you should really check out the skull of a dinosaur called Parasaurolophus. That guy had sound figured out a very long time before we did. ****, I just realized I'm a dork.