High frequencies break glass?

There was an experiment on the television a few weeks ago in which a woman with a high-pitched voice tried to break a drinking glass by screaming.

A glass was held a few feet from her, and she sang with a very high-pitched voice, so loud it was almost painful to listen. After a few seconds the glass shattered. I assume that there was no trickery on the part of the television station, as it all looked real.
I had never seen this before, and was wondering if it was uncommon.

Is it possible for a glass to break if there is a high-pitched scream near to it and if so why?

The master speaks:


You obviously never saw the famous commerical with Ella Fitzgerald and a Memorex tape.

For those who lack the vocal range to do this trick temselves, there is always the infamous beaker breaker.

The actual pitch depends on the shape of the glass. I’ve seen large sheets of glass cracked by very low frequency notes.

If the pitch of the note hits a resonant frequency of the glass, and continues, the glass will quite likely break. The resonant frequency depends upon shape, thickness, size and the elastic properties of the glass material.

The resonant frequency of the glass can be found by wetting a finger and running it slowly around the rim. After the right wetness is achieved you get a nice clear tone from a thin, high quality glass.

MEMOREX WAS FAKED? The story I heard (back in the 70s) was that Ella couldn’t break the glass, so Memorex helped things along by shooting it with a BB gun.

Is there any evidence at all that an UNAMPLIFIED human voice can shatter glass?

If you play 100 watts of pure sine wave through a one-inch pipe which is held close to a wine glass, you CAN shatter the glass. This suggests that the singer would have to put their mouth very close to the glass if they wanted to break it (otherwise the sound pressure would be much weaker, inverse square law and all.)

But if I remember the Memorex commercial, Ella didn’t hold the glass up to her mouth. Instead it was several feet away. If my memory is right, then this is good evidence that the commercial was faked (at least the part about a singer breaking glass, as opposed to a loudspeaker/amp/microphone doing it.)

I would think a trained opera singer might just do it if the precise note could be struck.

[frivolry]I do remember a funny scene in which an opera soprano knocked Victor Borge right off his piano bench. So he picked himself up, sat down and pulled a seat belt out of the bench.[/frivolry]

bbeaty, you obviously did not notice or else did not follow the link I made in my post concerning Ella Fitzgerald and Memorex.

If you go to my link you will find:
[ul][li]a link to a site explaining how glass can be broken by sound[/li][li]an explaination of how Memorex may have fudged, but not faked the facts.[/ul][/li]

As to the story you heard back in the 70’s could we have a cite? Please. :smiley:

And how many people do you think will recognize who Victor Borge is? :cool:

And how many people do you think will recognize who Victor Borge is? :cool:


Let’s do it this way:

I doubt that a human being could break a wineglass by singing at it. Is there any evidence that someone has EVER done this? If not, then I refuse to leap to conclusions not based on evidence.

Yes, if you use a microphone and amplifier then that’s totally different. I first saw articles about this in THE PHYSICS TEACHER back in the 1970s. With a few hundred watts going through a single driver, I bet that even I could shatter a wineglass with my amplified voice.

I did. I saw nothing about Ella breaking a glass using her unmodified unamplified lungs and throat (no power amp, no loudspeakers, no nothing.) All the demos in the physics magazines show that it’s trivial to break a glass using a loudspeaker and amplifier.

The Memorex ad seems to be about the singing of a perfect pitch, not about shattering a glass using JUST your vocal chords.

I suspect that most anyone can break a glass by using a microphone, amp, and transducers capable of 500 watts or so, and an Ella F. isn’t needed.

Hmmm. I wonder what the shattering glass looks like if you view the Memorex ad frame by frame. Will cracks start near the rim where the maximum oscillation is? Or will they “star” outwards from a particular point, as if hit by a pellet?

Well, kniz, this is the internet. Anyone can type Victor Borge into the “Search” box and get the answer. Anyone who isn’t curious enough to find out about this exceedingly funny guy is the loser.

So there!

I knew who Victor Borge was even without searching. Does that count for something? :smiley:

Victor Borge may not be able to break a glass with his voice, but I always bust a gut laughing when I see him.

For what it’s worth, the pitch does not have to be high. I’ve see Bowser do it with a low voice, but don’t know whether he had electronic amplification assistance.