Okay, so you know how you can sing high enough to break glass? It's actually easier than most media makes it out to be. What you have to do is sing the resonant frequency that matches up with the natural frequency of the glass. Basically, everything has a frequency at which it naturally vibrates. So, if a note is sung, or played whatever, the object starts to vibrate along with it, causing more sound to be produced, causing it to vibrate harder etc etc. Make an object vibrate hard enough, and it will shatter. Obviously, the easiest type of material to do this with would be glass, considering, well, it's glass. And, the other thing I've found is that the resonant frequency isn't all that high, I could even hit the note after a warm up. The main issue with the process is that the note has to be played at extremely close ranges and extremely loud. So, put an amplifier right next to the glass. Yeah, I'm gonna break glass with my voice. This is gonna be awesome.