Here's What It Takes to Shatter Glass With Speakers


What better way to demonstrate the science of sound than by breaking stuff? For the latest installment of the new Tested web series Simple Feats of Science, host Kishore Hari and Zeke Kossover from San Francisco's Exploratorium conducted an experiment to see if basic car speakers could break a pane of glass. Using a custom-built speaker box and an audio device playing barely audible, low-frequency tones, the duo demonstrate how sound waves work without doing damage to their ears in the process.

This isn't the typical experiment involving wine glasses and high-pitched sounds. In the video above, Kossover explains how his team's version is different. "Breaking glass with sound is incredibly cool, however that high-pitched sound is really close to the most sensitive part of your hearing so it sounds super loud," he said. Those experiments are also difficult to do because of the strength of the glasses required, he added.

Instead, Kossover positioned the speakers in his custom box so that they faced opposite directions, which created pulses of air pressure inside the box's three chambers. The box is sealed so that the pressure only has three ways to escape (through three holes in the top). Kossover then gradually lowered the frequency until he found the sweet spot—the resonant frequency of the glass–causing it to break.

Check out the full experiment above and head to the Tested YouTube page for more cool science.

[h/t Tested]