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Why Does Inhaling Helium Make Your Voice Sound Funny?

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Helium's atomic number is 2 and its atomic weight is 4.002602. Its boiling and melting points— -452.1°F and -458.0°F, respectively—are the lowest among the elements. It is the second most abundant element in the known universe (after hydrogen). And it makes your voice sound really funny when you inhale it. Here's why.

A Crash Course in Sound

When you speak, air travels up from your lungs and through the larynx, where it meets the vocal cords (or vocal folds), twin infoldings of mucous membrane stretched horizontally across the larynx, and hits the underside, causing them to vibrate. The vibration of the cords excites air molecules in your vocal tract and sets up resonant frequencies. The vibration of the vocal cords influences the pitch (the perceived fundamental frequency of a sound) of your voice; the vibration of the air in the vocal tract influences your voice's timbre (the quality of a sound that distinguishes different types of sound production—remember that for later, it will be important); and manipulation of the vocal tract—moving your tongue, lips, etc.—creates different resonant frequencies and allows you to make the different sounds of speech, like "oohs" and "aahs." Your voice finally leaves your mouth in the form of waves, oscillations of pressure transmitted through a medium.

Voice, Meet Helium

In addition to the vibrations and manipulations that influence the sound of your voice, what another person hears when you speak also depends in part on what the space where the sound is created contains. The air that fills a room where you might be speaking to someone is made up of roughly 78.08 percent nitrogen, 20.95 percent oxygen, 0.93 percent argon, 0.038 percent carbon dioxide, and tiny amounts of other gases. Nitrogen, which makes up the majority of our air, has a mass roughly seven times greater than that of helium. Because helium is lighter than air, sound waves travel through it faster. In a room where the temperature is 68 degrees Fahrenheit, sound travels at 344 meters a second through air, but 927 meters a second through helium. When you inhale helium, you're changing the type of gas molecules in your vocal tract and increasing the speed of the sound of your voice.

Some people think that helium changes the pitch of your voice, but the vibration frequency of the vocal cords doesn't change along with the type of gas molecules that surround them. When your vocal tract is filled with helium, your vocal cords are vibrating at the same frequency as usual. It's actually the timbre (again, the quality of a sound that distinguishes different types of sound, also known as tone quality or tone color) that changes, because those lighter-than-air helium molecules allow sound to travel faster and change the resonances of your vocal tract by making it more responsive to high-frequency sounds and less responsive to lower ones. Your voice winds up flat and Donald Duck-esque and listeners perceive this as a change in pitch.

More Fun With Gases

If a lighter gas like helium gives us a squeaky-sounding voice, you might to assume that a heavier-than-air gas would amplify the lower resonant frequencies and make it deeper and richer (trading Donald Duck for Barry White, if you will). You'd be correct; gases like xenon and sulfur hexafluoride slow the speed of sound and lower the resonant frequencies of your vocal tract. 

No Fun With Gas

As amusing as the results are, inhaling helium is not so great for you. While you're inhaling it, you're not getting the oxygen you need for normal respiration. Breathing helium continuously can cause asphyxiation within a few minutes. That light-headed feeling you get from a few inhalations is a sign you need to take a break. And please don't ever inhale helium directly from one of those pressurized tanks. The high flow rate can 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, seizures and death.

This story originally appeared in 2009.

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Big Questions
Why Do Cats Freak Out After Pooping?
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Cats often exhibit some very peculiar behavior, from getting into deadly combat situations with their own tail to pouncing on unsuspecting humans. Among their most curious habits: running from their litter box like a greyhound after moving their bowels. Are they running from their own fecal matter? Has waste elimination prompted a sense of euphoria?

Experts—if anyone is said to qualify as an expert in post-poop moods—aren’t exactly sure, but they’ve presented a number of entertaining theories. From a biological standpoint, some animal behaviorists suspect that a cat bolting after a deposit might stem from fears that a predator could track them based on the smell of their waste. But researchers are quick to note that they haven’t observed cats run from their BMs in the wild.

Biology also has a little bit to do with another theory, which postulates that cats used to getting their rear ends licked by their mother after defecating as kittens are showing off their independence by sprinting away, their butts having taken on self-cleaning properties in adulthood.

Not convinced? You might find another idea more plausible: Both humans and cats have a vagus nerve running from their brain stem. In both species, the nerve can be stimulated by defecation, leading to a pleasurable sensation and what some have labeled “poo-phoria,” or post-poop elation. In running, the cat may simply be working off excess energy brought on by stimulation of the nerve.

Less interesting is the notion that notoriously hygienic cats may simply want to shake off excess litter or fecal matter by running a 100-meter dash, or that a digestive problem has led to some discomfort they’re attempting to flee from. The fact is, so little research has been done in the field of pooping cat mania that there’s no universally accepted answer. Like so much of what makes cats tick, a definitive motivation will have to remain a mystery.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Big Questions
Why Do Baseball Managers Wear Uniforms?
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Basketball and hockey coaches wear business suits on the sidelines. Football coaches wear team-branded shirts and jackets and often ill-fitting pleated khakis. Why are baseball managers the only guys who wear the same outfit as their players?

According to John Thorn, the official historian of Major League Baseball since 2011, it goes back to the earliest days of the game. Back then, the person known as the manager was the business manager: the guy who kept the books in order and the road trips on schedule. Meanwhile, the guy we call the manager today, the one who arranges the roster and decides when to pull a pitcher, was known as the captain. In addition to managing the team on the field, he was usually also on the team as a player. For many years, the “manager” wore a player’s uniform simply because he was a player. There were also a few captains who didn’t play for the team and stuck to making decisions in the dugout, and they usually wore suits.

With the passing of time, it became less common for the captain to play, and on most teams they took on strictly managerial roles. Instead of suits proliferating throughout America’s dugouts, though, non-playing captains largely hung on to the tradition of wearing a player's uniform. By the early to mid 20th century, wearing the uniform was the norm for managers, with a few notable exceptions. The Philadelphia Athletics’s Connie Mack and the Brooklyn Dodgers’s Burt Shotton continued to wear suits and ties to games long after it fell out of favor (though Shotton sometimes liked to layer a team jacket on top of his street clothes). Once those two retired, it’s been uniforms as far as the eye can see.

The adherence to the uniform among managers in the second half of the 20th century leads some people to think that MLB mandates it, but a look through the official major league rules [PDF] doesn’t turn up much on a manager’s dress. Rule 1.11(a) (1) says that “All players on a team shall wear uniforms identical in color, trim and style, and all players’ uniforms shall include minimal six-inch numbers on their backs" and rule 2.00 states that a coach is a "team member in uniform appointed by the manager to perform such duties as the manager may designate, such as but not limited to acting as base coach."

While Rule 2.00 gives a rundown of the manager’s role and some rules that apply to them, it doesn’t specify that they’re uniformed. Further down, Rule 3.15 says that "No person shall be allowed on the playing field during a game except players and coaches in uniform, managers, news photographers authorized by the home team, umpires, officers of the law in uniform and watchmen or other employees of the home club." Again, nothing about the managers being uniformed.

All that said, Rule 2.00 defines the bench or dugout as “the seating facilities reserved for players, substitutes and other team members in uniform when they are not actively engaged on the playing field," and makes no exceptions for managers or anyone else. While the managers’ duds are never addressed anywhere else, this definition does seem to necessitate, in a roundabout way, that managers wear a uniform—at least if they want to have access to the dugout. And, really, where else would they sit?

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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