The pitch of your voice is determined by the air you breathe. Helium makes your voice squeaky because it is a light gas. Sulphur Hexafluoride makes your voice deep because it is a heavy gas.
Every human has their own natural vocal range, and it’s hard to make your voice higher or lower without actually exercising your thorax. However, the quality of your sound isn’t a feature of your voice, but rather depends on the air you’re breathing.
The pitch of your voice would be different if you were breathing Martian air, or any other air composition, for that matter. Earth’s atmosphere is composed of 20% Oxygen and 79% Nitrogen; the remainder is made up of Argon, Hydrogen, Carbon Dioxide and other gases. This mixture gives your voice the sound that you think that you ‘have’. If you were to breathe pure oxygen, for example, your voice would be a little lower than normal. If you were to breathe pure carbon dioxide… you would probably die.
The most interesting thing about breathing weird gases is that they change your voice, but you can do absolutely nothing about it. Even trying to change it while the gas is in your lungs simply doesn’t work. The “gas user” has to wait for as long as it takes for that substance to move out of the lungs and clear the throat. There are two audio clips below that will make you realize how different your voice sounds when you inhale Helium and when you inhale Sodium Hexafluoride.
Breathing Helium (The Squeaky Voice Gas):
Helium is the second lightest gas on the periodic table, and non-lethal in small quantities. This makes it extremely useful when you want to freak out your friends by impersonating Alvin the Chipmunk. To make your day better, here’s Morgan Freeman after sucking up some Helium.
Breathing Sulphur Hexafluoride (The Deep Voice Gas):
Although there are many gases that make you sound like Morgan Freeman, Sulphur Hexafluoride is the best candidate if you want to avoid dying within seconds of inhaling it. To be more specific, it is one of the only non-poisonous gas heavy enough to make your voice lower than normal. Xenon, which is a noble gas, can also have the same effect on you but it is very rare and expensive. Other options would include Nitrous Oxide also known as laughing gas used by dentists during surgeries. It has the added benefit of ‘relaxing’ you, for lack of a better word, accompanied with visual distortions and euphoria. So, if you want to be able to remember your name while you try to lower your voice, sulphur hexafluoride is the way to go. Also, it makes you sound like Arnold Schwarzenegger trying to impersonate Sylvester Stallone.
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Before we tell you how to do this, we should probably tell you why you shouldn’t do this. Note that you should not inhale multiple breaths of either gas, as you might cause yourself to asphyxiate. You should definitely stop if you start feeling lightheaded. The high flow rate of the gas can also rupture your lung tissue or send a concentrated mass of gas into your bloodstream, after which it can lodge in the brain and cause a stroke, seizure or death. Therefore, don’t inhale large amounts of the gas in one go; instead, take smaller sips.
Helium is ‘relatively’ harmless because it is lighter than air and will gradually move out of your lungs through your mouth just by floating up. Sulphur Hexafluoride, on the other hand, would settle inside your lungs and block the flow of oxygen if you inhale it in large amounts. Of these two gases, Helium is quite easily available and is used in balloons to make them rise. Sulphur Hexafluoride, however, is a heavy gas and is not naturally available. Both of these can be used to fill up a balloon and then inhaled.
Why does inhaling a gas change your voice?
It all starts with the air in the lungs. As air passes from your lungs to the outside of your mouth, it is manipulated in several different ways. The sound that is radiated when we speak is a superposition of the normal modes in our mouth cavity brought about by the vocal chords in our throat (or thorax). Nearly all human speech sounds range from approx. 200 hertz – 8,000 hertz, meaning that the sound waves vibrate approx. 200 – 8,000 times per second.
Together, the sound we hear, which is created by air flowing at different frequencies and resonances, is what defines our voice. Another factor affecting pitch is the thickness of one’s vocal cords. The thicker the folds of skin, the deeper the voice. This is due to the mass of your chords, which the air has to manipulate. As you would expect, men tend to have much thicker folds of skin than women, and therefore a lower voice than females too!
The only difference in gases that is responsible for changing your voice is mass. Sound travels slowly in gases that are heavier and faster in gases that are lighter. Although your throat produces sound at a certain fixed frequency, the quality heard by others is lower for sounds traveling slower. Helium is almost seven times lighter than air, which means that the sound wave traveling in Helium will be much higher than normal air. The opposite is true for Sulphur Hexafluoride, for which the sound wave is slower than normal.
Basically… if you inhale both of these together, you’ll sound something like Adele.