Science tells us that you absolutely can break a wine glass with your voice, and it all comes down to how sound waves react with other objects. Live Science explains that all objects have what is called a natural frequency. You can hear a wine glass's frequency when you rub your wet finger around the rim. Voices have a natural frequency, too, and they can shift the air molecules around nearby objects. Sound waves close enough to a wine glass can make the glass vibrate, a process called resonance. Enough vibration will result in so much resonance that the glass will eventually break.
But there's more to it. Scientific American explains that the volume of sound is also related to how it displaces air. When a singer sings really loudly, the sound molecules are creating a great deal of resonance. Opera singers train to sing loud, and some of their voices can reach up to 100 decibels, which is about as loud as a bulldozer, according to Bacou-Dalloz Hearing Safety Group. At that point, breaking a delicate glass might be possible.
