In a shattering episode of the PBS show Physics Girl, host Dianna Cowern partnered up with Mike Boyd of Learn Quick so that he could teach her how he was able to break a wineglass with his voice. After a few tries, Cowern finally hit the right note and broke the glass. She then explained the physics behind this phenomenon, specifically the resonant frequency and oscillating system of a wineglass.
In the wineglass that frequency is the note it vibrates at if you flick it and let it ring. By the way musical notes can always be described by their frequency or frequencies. …Now the wineglass analogy is that if you sing at the glass at its resonant frequency your vocal cords are vibrating the air molecules that vibrate the glass and drive it at its resonant frequency and …will go higher and higher the glass will vibrate or shake harder and hard and if you shake something hard enough it will eventually break