There is an opinion that a very strong voice is able to turn glass objects into fragments. We checked whether this is so.

Many remember the wonderful Soviet film "Jelsomino's Magic Voice" based on the tale of Gianni Rodari. His hero possessed such amazing vocal cords that he could destroy the walls, not to mention the usual window glass. But if the boy achieved this involuntarily, without effort, then in real life everything is different. There are legends that owners of especially impressive vocal data (usually opera singers) are able to make a small glass object, for example, a glass. One of the most famous such legends is about the great bass Fedor Chaliapin. “When he sang to the full power, candles went out, chandeliers were shaking, faceted glasses cracked” - something like this is the power of bass Chaliapin in numerous sources online. Grotto Chaliapin near the village of New Light in Crimea received, According to legend, the name for the fact that when the maestro performed here, his powerful voice was reflected from the walls and smashed the glass with champagne in the singer’s hand. On the other hand, the wife of the famous tenor Enriko Caruso in her book refutes a similar legend about his husband.

In the 70s in the USA, Memorex's speakers advertising was popular. In it, the glasses burst from the voice of the first lady of Jazz Ella Fitzgerald. However, advertising is an information that is not worth it unconditionally:

Since we are talking about a physical phenomenon, I would like to have both its theoretical justification and practical confirmation. Let's start with the first.

Sound is wave vibrations distributed in space with a certain frequency. The wave, reaching the glass, makes it vibrate. Here we are dealing with such a phenomenon as resonance, which manifests itself in a sharp increase in the amplitude of oscillations when the sound frequency coincides with the oscillation frequency, characteristic of glass of this thickness, composition and shape.

The harmony of these two frequencies, multiplied by sufficient power, can make the glass burst. In other words, if we say, on the example of a glass for wine, for this you need to make a sound, the frequency of which coincides with the resonant frequency of its own oscillations of the glass. It is intuitive that it should at least be a sufficiently powerful sound. But how to determine its necessary and sufficient parameters?

Here's what the famous Dutch professor Walter Levin writes about this in his book "The eyes of physics":

“I personally have never seen an opera singer who breaks a glass of a glass, and therefore I do not attract them to my experiments. I take a glass, lightly knock on it with a spoon and measure its main frequency with the help of an oscilloscope-it is clear that it varies from the glass to the glass, but for those that I use, it always fluctuates somewhere in the range from 440 to 480 hertz. Then I electronically generate the sound of exactly the same frequency (well, quite accurately, of course, this is impossible to do, but I try to get the closest meaning). I put the glass to the amplifier and slowly increase the volume. Why am I doing this? Because the louder the sound, the more energy in the form of a sound wave will hit the glass. And the larger the amplitude of the oscillations in the glass, the more glass will bend inside and bend back - until it breaks (which I count on, conducting a demonstration).

To show that the glass is vibrating, I largely lead a camera on it and illuminate a strobe -compete with a beam, adjusted to a slightly different frequency than a sound. It's just incredible! You see how the glass begins to vibrate; Its two opposite sides first converge, and then diverge, and the distance that they shift is growing and grows as the speaker volume increases. Sometimes I have to configure the frequency a little, and then bam! - And glass fragments. This part of the experiment especially likes students; They just can’t wait until the glass bursts. ”

So we smoothly moved to the experimental part. In the example of Levin, the glass was broken using a technical device, and we are interested in the effect of the human voice. Naturally, it would be interesting to ask whether the creators of the famous program “Destroyers of Legends”, who like to check various stable stereotypes associated with physical phenomena, dealt with this issue. Indeed, already in the first season of the famous show, an episode called Breaking Glass (“Broken the glass”) was released.

The creators of the program to achieve their goal invited a rock singer and vocal coach Jamie Wender. It was possible to break the glass with the help of the amplifier quickly - even the presenters were able to do this. Another thing is to achieve success in a natural voice. Vender tried more than ten different vessels before he stumbled upon the only one who split from his mighty vocals:

For the first time, the evidence that a voice without outside help can really break glass was shot on video. It should be noted that in his victorious attempt, Wender's voice reached an indicator of 105 dB - almost as loudly as a jack of a hammer. This is much higher than the capabilities of an ordinary person. According to the magazine Scientific American, even opera singers have been training for years to reproduce stable notes at a volume above 100 dB.

In addition, one cannot but pay attention to the dependence on a specific glass. Vessels that look equally naked eye can have radically discounted strength on a break, which allows one of them to withstand a much more powerful effect than others. In other words, success here greatly depends on the location, depth and form of microcracks.

Nevertheless, the legend, as we are convinced, is absolutely fair: the human voice can be broken by glass.