Why does your voice change when you breathe helium? Question to the scientist: Why does helium distort the voice? Candidate of Chemical Sciences, scientific columnist for Russian Journal and Science and Life journal

Sound is the propagation of waves in an elastic medium (gas, liquid, solid body) and is born from vibrations of something (a ruler clamped in a vice, a loudspeaker membrane, air in a pipe, a string, etc.). The higher the oscillation frequency (the greater the number of oscillations per second), the higher (thinner) the sound. On the contrary, the lower the oscillation frequency, the lower (rougher) the sound. Too high sound (ultrasound, with a frequency above 20 kHz) we do not hear. Too low sound (infrasound, with a frequency below 16 Hz) is also not perceived by the human ear.

If you inhale helium (before that, it is better to take a deep breath), then the ligaments will not be in the usual air environment, but in the helium one. Helium is a very light gas normal conditions the density is 7 times less than that of air. In a less dense medium, bundles (like strings, for example) vibrate at a higher frequency. Imagine that you are clapping your hands in water and in air - just like that, it is easier for the cords to oscillate in helium than in air, which is seven times more dense.

It can be assumed that if you breathe in some gas (harmless, of course), whose density is greater than that of air, then the voice, on the contrary, will become lower.

Such a safe and colorless gas exists and is often used in physics demonstrations. This is sulfur hexafluoride (or sulfur (VI) fluoride, SF 6). Its density under normal conditions is 5 times higher than the density of air. The ligaments in it fluctuate with less frequency and the voice therefore becomes rougher.

We note as additional information that in addition to high density, sulfur hexafluoride has a high breakdown voltage (89 kV / cm), i.e., it is a very good insulator (this is shown in the video). This property is used in high-voltage electrical engineering, and one of the names of this gas - SF6 - is an abbreviation for "electric gas", which was given in the USSR, where this property was discovered in the 30s.

It is also interesting to know what frequencies the human voice can produce in general. The best voices are trained, choreographed singing voices. The bass has the lowest sounds (80 Hz-350 Hz), the highest sounds have the soprano (up to 1400 Hz). Some singers are able to take the note F of the third octave (aria of the Queen of the Night in Mozart's opera "The Magic Flute") - 1396.9 Hz and even the note G of the third octave (aria "Io non chiedo, eterni Dei" for soprano and orchestra, Mozart KV316) - 1568 Hz.

There are also incredible records of hitting the lowest or highest notes. Thus, the lowest note, almost inaudible to the ear, was recorded by Tim Storms from the USA - 8 Hz. Singer Mariah Carey sang a note up to the 4th octave (2093 Hz). In 2014, a national record was set in Ukraine (in Kyiv) - singer Svetlana Podyakova took up to 5 octaves! And in 2008, Adam Lopez took a note in C-sharp of the fifth octave, for which there is not even a key on the piano (the rightmost key of the piano is up to the 5th octave) - this is more than 4000 Hz!

And this is without any helium and sulfur hexafluoride!

It would seem that this topic has nothing to do with vocals. Rather, to chemistry ... Or physics ... Or acoustics, as part of physics ... And yet the influence HELIUM(and not only him alone, as you will learn from the article) on VOICE shows the validity of the view on how the human voice arises and what laws it obeys.

So, when inhaling a light inert gas - helium, for example, from balloons, a person's voice completely changes. You don't know about it yet? Yes, yes, amazing - nearby ...

Sounds really funny! The effect is so interesting that even such famous people as the hosts of the MythBusters program on the Discovery TV channel did not pass by. But!

roller on English language, but it's not scary, there is quite a suitable translation:

"I promise it will be cool, but you have to promise that NEVER don't repeat this at home! Okay? Okay! And now... Everyone knows that my voice will sound higher if I inhale helium! This is because it is 6 times lighter than air which means my vocal cords will vibrate faster and it makes my voice sound a lot higher!
And now ... I will breathe in sulfur hexafluoride, which is 6 times heavier than air, and the voice will sound something like this ...
My voice sounded much lower...
In general, I still have fun!
THIS IS SCIENCE !!!»

An inquisitive and curious person would naturally like to know WHY is this happening? And there are no answers to this question ... One of them has already been given - my vocal cords will fluctuate faster ... But, is it really so?

There are other "reasons" - the difference in air and helium pressures, "compression" of the vocal cords, and even the fact that INERT(!) gas somehow affects itself STRUCTURE vocal cords! Mind unbelievable!

People don’t know physics… Absolutely…

And the true reason is quite simple and has long been studied by science. Yes, in fairness it must be admitted that bundles operating in a medium not of air, but of helium (and, of course, sulfur hexafluoride) oscillate a little faster (slower). But only LITTLE! And this degree of change in the speed of vibrations cannot affect the voice in any way. SO MONSTERIOUS! The main factor is different.

Think for yourself, because if the vocal cords themselves experienced any impact, then the voice could be higher or lower, but its timbre would not change! The voice would still be HUMAN, albeit higher or lower. But something quite different is observed - INHUMANITY vote! It is the change TEMBRA in the direction of his "pinocchio", "cartoon" causes uncontrollable laughter! The same effect occurs when the voice is “lowered” – “demonic”, “monstrous”, but in any case, there is no resemblance to a human voice.

But TIMBRE the human voice - a set of formants, as described in the article "What are formants?" . The formants themselves are impossible without the participation RESONATORY SYSTEMS human body. And not only! Higher HUMAN a voice is a complex sound wave consisting of the same formants, but not only the formants themselves are modified, but also their individual arrangement in the spectrum of the voice. Therefore, we hear, though high (or low), but, most importantly, a human voice. Change the same ENVIRONMENTS, the replacement of air with another gas does not lead to a change in the configuration of the resonator cavities, as a result, the formants do not shift relative to each other, but simply change their frequency. Rumor fixes this as the "artificiality" of the voice.

This is the confirmation of both the existence of the resonator system itself and its fundamental influence on the very phenomenon of the voice. Well, the refinement of the process from the point of view of physics ... Excuse me:

“The human vocal tract consists of vocal cords and a resonator filled with air (or helium): lungs, respiratory tract, cranial cavities. The ligaments generate a faint sound, without a resonator we might not hear it. The resonant frequencies of the vocal tract depend on its volume and shape. Helium has a lower density than air, so the speed of sound in it is higher (965 m/s versus 331). The frequency, wavelength and speed of sound in gases are related by certain relationships. This results in the fact that, although the configuration of the resonator does not change, higher frequencies become resonant, and the overall spectrum of the voice shifts to higher frequencies. In musical terms, helium does not change the pitch of the voice, but its timbre. More precisely, the pitch changes, but very little - it depends mainly on the tension of the vocal cords, and when helium is exhaled, it is slightly different than when air is exhaled.

“... the throat is, from the point of view of acoustics, a cavity resonator tuned to a certain wavelength (not frequency!). And if a person breathes air, then a sound (voice) of a certain frequency is obtained ... But if now we take helium instead of air, then FOR THE SAME WAVE LENGTH due to the higher speed of sound, a different frequency will result - a higher one. And when moving from one medium to another (from a helium-filled pharynx to normal air), the sound frequency no longer changes.

So, dear reader, the links do not change in any way! The whole thing is in ENVIRONMENT! And the main "builder" of our voice is resonance.

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Probably each of us knows that if you inhale a little gas from a helium balloon, then the voice will become thinner and will sound funny. But not everyone will be able to answer why the voice changes from helium when the gas is inhaled ?! And all because helium has a much lower density. The vocal cords vibrate elastically in the air stream. And since the density of helium is seven times lower than air, it means that it loads the ligaments much less, which is why they vibrate with a higher frequency and the voice becomes squeaky and funny.
Now let's take a closer look at how and why helium changes the voice. The mechanics of the human voice is an amazing biological phenomenon. It all starts with the fact that air enters the lungs through the larynx and then leaves the lungs in the form of carbon dioxide again through the larynx. This can be manipulated in several ways. For example, you can release the air, and all that is heard by others is the sound of breathing. If you need to say something, the muscles of the larynx and vocal cords are included in the matter.

The air in your lungs pushes your diaphragm to relax. It then travels through your windpipe and into a small opening that has two folds of skin (vocal cords) on either side of it, in the shape of a V. As the muscles that control your voice tense and relax, they create the vibration of the cords. When these cords vibrate, they release pulses of air. Tension in these muscles creates differences in frequency. The higher the voltage, the higher the frequency and therefore the higher the voice. This frequency is measured in hertz (well, that is, how many times per second it repeats). For example, almost all human speech sounds usually range from 200 hertz to 8000 hertz.

After exiting the vocal window, the air moves into an area of ​​your mouth that can be informally called your vocal tract. As you manipulate your tongue, jaw, and lips, you can change the resonant frequencies created by your vocal connections, producing many different speech sounds.
The sound created by air flowing at different frequencies and resonances creates our voice. Another factor affecting stride is the thickness of the vocal cords. The thicker the folds of the skin, the deeper the voice, and vice versa - the thinner the folds and the thinner the voice.

So now let's talk about the air that comes out of your lungs. The number of molecules in a fixed volume of gas, like the volume of air in the lungs, does not change with the type of gas (assuming the pressure is low enough). As long as the temperature and pressure are the same, it doesn't matter if it's helium or air, the number of molecules is the same. The mass of these molecules is then measured by atomic weight. Atomic weight is a dimensionless physical quantity (which is why it works so well for a gas that doesn't necessarily have a given size). This is the ratio of the average mass of an element's atoms compared to 1/12 of the mass of a carbon-12 atom. All this basically means is that the higher the number, the heavier the gas.
Helium has an atomic weight of 4.002602. Air, which is approximately 80% nitrogen, has different characteristics depending on environment. Because of this, its actual atomic weight cannot be accurately determined. However, it is typically about seven times heavier than helium.

So, why does the voice change from helium when the gas is inhaled?! The answer lies in how sound waves travel through a given gas. The denser or heavier the gas, the slower the sound wave will be. Helium is much lighter than air. Then the speed of the sound wave through helium will be much higher. So when you inhale helium and use it as a source of perceived sound, you simply increase the speed or frequency of your voice. You don't change the pitch, as your vocal cords vibrate at the same rate as when you use air. You also do not change the configuration of your vocal tract. So while the fundamental frequency of the chords remains the same, the frequency of the sound heard by others increases due to the wave traveling through helium much faster than through air.

There is a trick that can be seen many times on YouTube videos. These videos can be found if you search for the words "helium" and "voice". We see that after a person inhales helium gas, his voice changes, becomes ridiculously squeaky. If a person inhales another gas, sulfur hexafluoride, which is heavier than air, his voice takes on bass tones, which is also unusual and therefore funny.

What is the reason for this phenomenon?

But first, let's answer the question, thanks to what we can speak at all. How does a voice come about?

This happens when air passes from the lungs through the trachea into the larynx. In the larynx, approximately in the middle of it, there is a narrowing where the vocal cords are located, which actually generate the sound. The vocal cords are two horizontal folds, between which there is an opening called the glottis. If the vocal cords vibrate as air passes through them from the lungs, sound is produced. The vocal cords can produce a wide variety of movements. They can close, connect, change their length and thickness, thereby producing a variety of sounds.

But the links themselves are very weak. Therefore, the sound produced by them is very quiet. A resonator is needed to amplify this sound. The role of the resonator in the human vocal tract is performed by the pharynx. Throat is voluminous. It opens towards the mouth opening. The shape of the pharynx is wrong, but this shape is so cunningly “calculated” by nature that it amplifies the weak vibrations of the air that the vocal cords generate and directs them from the mouth towards the listener. The pharynx is located directly next to the bones of the skull. As a result, our voice travels to our ear not so much through the air as through our cranial bone. A strange effect is connected with this: we hear our own voice differently than the people around us hear it.

So, the human vocal tract is very similar to any sound-reproducing apparatus: it has a generator of sound vibrations (vocal cords) and an amplifier-resonator (pharynx). The nose and mouth, as well as the tongue, lips and palate in the mouth, are involved in articulation. Thanks to them, a person changes the sounds generated by the vocal cords and amplified by the pharynx, and pronounces words. If we draw an analogy with a radio transmitter, the main signal is modulated by the information signal.

What happens when a person inhales helium gas and starts talking? Due to the fact that helium is lighter than air, the vocal cords in the environment of this gas will fluctuate a little faster. But it is not because of this change that the tone of the voice rises so dramatically.

But for our throat, which, as already mentioned, works as a resonator, a change in the nature of the sound transmission medium is significant. After all, the resonant frequencies of the pharynx depend on its shape and volume. When air is replaced with helium, the speed of sound in the resonator almost triples, from 331 m/s to 965 m/s. But the configuration of the resonator has not changed. Therefore, the resonator will now enter into resonance (and therefore amplify) other, higher frequencies. All sounds coming out of the mouth of a person who "sipped" helium will shift towards higher frequencies. The voice will become more squeaky.

If, instead of light helium, we inhale a gas heavier than air, in which the speed of sound is lower, resonate with the pharynx, which means that sound vibrations with a lower frequency will be amplified. The voice will shift towards low frequencies and become unnaturally rough.

This is how all these miracles are explained.