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The human voice can break glass. (Andrey Armyagov/Getty Images/Hemera)
The human voice can break glass. (Andrey Armyagov/Getty Images/Hemera)


Vino veritas: the proof is in a glass Add to ...

Welcome to Opera Night at the CW Café. This evening, we feature Dame Volumina Voxissima with an ear-splitting selection from Verdi’s La Shatterata. Okay, folks, hang on to your wineglasses.

The question

Ten-year-old Nathan DeNigris of Ottawa wants to know if the human voice really can break glass.

The answer

Mississauga acoustic engineer John Swallow says that, as a student at the University of Toronto, he experimented with exposing glass jars to sound, trying to find defective ones. He thought that perhaps by pounding the jars with sound and making them vibrate, they might break at the weak points. “No such luck, no matter what we did,” he writes.

“We also took several wineglasses, both cheap and expensive, and blasted each with sound, with no luck, until the sound was tuned like an opera singer’s voice to exactly the resonant frequency of the glass, but 100 times louder than a voice. Even then, it took 20 minutes to break a cheap glass. Expensive ones lasted longer.”

The sound made the wineglasses vibrate and ring like a bell, he says. The vibration caused distortion in the rim of the glass, “with the circular rim alternately flattening in the north-south direction, then in the east-west, a natural vibration mode, all at a pitch of about high C. It was vibrating so much it was a blur,” he writes.

So, it’s obviously very difficult to break glass using sound, but could an unamplified human voice perform the task?

Yes, says Alain Gingras of Notre-Dame-de-la-Salette, Que. He recalls watching an episode of the TV show Mythbusters in which they did succeed in breaking a wineglass with an unamplified human voice. “They had to try and try again,” he writes. “They had to get the right glass, the right singer and the right note.”

Finally, singing coach Jaime Vendera, holding the glass up close to his mouth, managed to break it by directing a long, high-pitched note right at it. However, it took him 20 tries before he succeeded.

So, yes, it seems it is possible to shatter glass with the human voice, but it surely isn’t easy.

Further notice

Here’s another helping of information on a food question we asked recently. It was this: If you could eat only one type of food, which food would keep you alive the longest?

Lee Handel of Victoria says he has a partial answer. “It’s partial,” he writes, “because this food must be supplemented a little with margarine, but otherwise it works as a ‘superfood.’ It’s the potato.”

He quotes the following passage from the book Propitious Esculent: The Potato in World History by John Reader.

“The most valuable asset of the potato is undoubtedly the balanced nutrition it provides. In controlled experiments, people have sustained active lives for months on a diet consisting only of potatoes (plus a little margarine), maintaining perfect health throughout and without losing (or gaining) weight.”

The drawback, however, is that participants in the studies had to eat two to three kilograms of spuds a day.

Help wanted

George Woolley of Aurora, Ont., wonders why some languages have nouns that are either masculine or feminine. “Is there an advantage to having this feature in a language?”

In February, says Sterling Campbell of Campbell River, B.C., the Royal Canadian Mint will start destroying one-cent coins. But what will it do with U.S. pennies in circulation in Canada?

Let’s hear from you: If you have the answer to one of these questions (or have a question of your own) send an e-mail to wisdom@globeandmail.com. Please include your location and a daytime phone number.

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