Q: Why does helium change the sound of your voice?

When you talk, air travels from your lungs to your larynx, also known as the voice box. Your vocal cords are stretched across the larynx. As air passes by, the vocal cords vibrate. These vibrations then resonate through the throat and nasal passages, creating sound.

Regular dry air is composed on about 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.03% carbon dioxide, and trace amounts of other gases. At 70 degrees Fahrenheit (about 21 degree Celsius), sound travels at a speed of 344 meters per second or 771 miles per hour in dry air.

But what happens when we introduce helium to the vocal tract?

Helium is the second element on the periodic table and the second most abundant element in the universe (after hydrogen). It’s roughly seven times less dense than air, allowing sound waves to travel through faster. At 70 degrees Fahrenheit, sound travels at 1090 meters per second or 2441 miles per hour in helium- three times as fast as the sound would have traveled through air.

It’s important to note that the vibration frequency of your vocal cords and voice pitch remains the same, regardless of whether you inhaled air or helium. The helium simply allows the sound to travel faster, changing the resonances of your vocal tract and affecting the timbre or tone of your voice.

The effect is temporary. It lasts only as long as helium is around your vocal cords. Once regular air replaces the helium, your voice goes back to normal. Of course, we’re not meant to breathe helium continuously. A couple breaths of helium are typically harmless. Too much can cause asphyxiation, so it’s vital to exercise caution when inhaling helium.

Keep calm and science on.

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