Did you ever inhale helium to make your voice sound like a cartoon character? I was recently reminded of this phenomenon while watching the movie My Best Friend's Wedding — the little brother and his friends inhale helium before the wedding and sing in harmony, sounding a bit like Donald Duck and family.
Have you ever wondered how that works and whether it is dangerous?
The Sound of Your Voice
First, it is important to understand what determines the sound of your normal voice.
It might seem simple, but the physical characteristics of air, and the shape of your throat, mouth, nasal cavities, tongue and lips all contribute to how you sound when you speak.
Voice begins in a part of the throat called the larynx (or voice box), where vocal cords vibrate when air passes between them. Whether your voice is high-pitched or low-pitched depends on the vocal cords' length and thickness. These differ in men and women, accounting for the lower pitch of most men compared with most women.
Helium is less dense than air; that's why helium balloons rise. As a result of its lower density, sound travels 2½ times faster in helium than in air. Faster speed means higher pitch, so as helium travels through your airway across the vocal cords, the pitch is much higher than usual.
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Is It Dangerous?
Inhaling helium for a breath or two is generally harmless. There are reports of brain injury and even death after inhaling helium, but these have occurred after prolonged inhalation (which leads to inadequate oxygen in the lungs and blood) or after inhaling the helium from a pressurized tank (which can force gas bubbles into the bloodstream, a dangerous problem that can cause a stroke).
So, there is generally little risk to the usual party trick of inhaling a small amount of helium from a balloon, and it wears off quickly, once air has a chance to replace the helium in your upper airways.
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The Benefits of Helium
Helium actually has been used on occasion to treat illness. In particular, a mixture of helium and oxygen has been used for patients with lung diseases such as asthma or related conditions in which the lungs' smaller airways become narrowed.
Because of its physical properties, helium can reduce turbulence and improve airflow in the lungs. Studies have demonstrated that treatment with a mixture of helium and oxygen can reduce breathlessness and improve lung function among patients with severe chronic obstructive pulmonary disease (COPD).
It also has been used for decompression sickness (also called "the bends"), a serious condition that can develop in deep-sea divers who come up to the surface too quickly. Brain injury or other nervous system problems can follow, but successful treatment with mixtures of helium and oxygen have been reported.
Finally, inhaled mixtures of helium and oxygen have been used to test how well the lungs are doing, similar to the pulmonary-function testing commonly recommended for people with asthma.
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The Bottom Line
The voice is an amazing instrument. While it may be best to avoid anything that might cause trouble to something so remarkable, briefly inhaling helium is unlikely to damage your voice or otherwise cause harm. However, prolonged inhalation and use of a pressurized tank certainly should be avoided.
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Robert H. Shmerling, M.D. is associate physician at Beth Israel Deaconess Medical Center and associate professor at Harvard Medical School. He has been a practicing rheumatologist for over 20 years at Beth Israel Deaconess Medical Center. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program.