The Scientific Reason Your Voice Gets Squeaky When You Inhale Helium
Needless to say, a sense of humor is a deeply personal thing. Some comedians swear just a little too much for some people's tastes, while others get their comedy kicks from that exact brand of humor. Comedian Frank Skinner said, per The Independent, "I don't want Gordon Ramsay to spoil it ... used properly, swearing really can be a beautiful thing."
We've all laughed uproariously at a clip on the Internet, showed it to a friend, and then been greeted with sheer bafflement and/or distinct unamusement. Some people think clowns are hilarious. Others are terrified of them. Variety, as they say, is the spice of life.
There's one silly jape that will almost always get a laugh from anyone, even a grudging and slightly judgmental one: the classic squeaky-helium-voice stunt. It's very difficult to resist. In our haste to amuse, though, we rarely stop to wonder about the science behind this odd effect. Here's how it works.
Lightweight helium has a curious effect on the air
Helium balloons have two vital purposes: to cause their owner dismay as they float up into the sky eight seconds after being purchased, and to be inhaled to cause that iconic squeaky voice effect. To understand both of these things, we'll need to take a look at the curious properties of helium.
Why does a helium balloon make an immediate bid for sky-based freedom the second you let go of the string? How Stuff Works explains that helium is lighter than air. Balloons aren't exactly heavyweights either, and so the balloon and its gassy contents can take off into the sky by displacing said air. ThoughtCo adds that those teeny atoms of helium gradually escape from balloons over time, which is why balloons will sag shortly after a special occasion and look very sorry for themselves.
The unique way that helium interacts with the air around us also causes that characteristic squeaky voice effect, though not in the way you might expect.
The high-speed, high-pitched helium hilarity
Per Live Science, our voices are curious instruments. There are so many elements, from the size of vocal cords to the shapes of vocal folds, that determine how our voices will sound. They're truly unique, just as fingerprints are. Inhaling helium dramatically alters the way the sounds our voices generate travel through the air, which explains the squeaky sound.
Sounds travels much more quickly through helium than through air, owing to the weight disparity between the gases. Sound is propelled by the oscillation of these gases, at a rate almost three times as quickly through helium (3041 feet or 927 meters in a second) than through air (1,128 feet or 344 meters per second).
The Sydney School of Physics (via Physclips) explains how this affects our voices. It demonstrates what happens when a subject is speaking while "keeping the tract configuration the same (i.e. trying to pronounce the same vowel as before, but with a throat full of helium)." The pitch of the voice is the same, reportedly, but "the speed of sound is greater, so the resonances occur at higher frequencies."
As a result, per Live Science, "certain high-pitch components of your voice become amplified relative to the low-pitch components, drastically changing the overall timbre of your voice." That's the scientific reason, but in the end, we have to thank science for giving us a little silly fun.