" Keep in mind that the other side of the wall would have to be infinitely big. It would have to be a very big space which would contain an infinite amount of fibreglass."
- You forgot to mention, impossible to construct. Do you listen to theoretical music too?
" My speaker invention would be ten times thicker at a fraction of the cost! "
- Fraction of the cost indeed, since it only can exist in your mind and you get what you pay for ...