I always thought that shattering glass with your voice was a myth. A way of illustrating how strong a voice was, but not actually a direct result of voice pitch and strength. I was wrong.
According to these instructions, with the right volume and frequency, you can in fact break a glass with your voice
. You'll need an amplifier, a crystal glass, a microphone, ear and eye protection, and a fierce voice. Have a read through the full instructions including their safety advice before giving this a try.
Every glass will have a different frequency at which it will shatter. You'll want to play around with different glasses and pitches. You can test the needed pitch by dipping your finger in water and running it along the rim of the glass, or tapping the glass gently. If you mimic your sound after the sound that these produce, you'll probably hit the right note.
Just don't try this with your wedding crystal in case it actually works.