Why Does Helium Make Your Voice Squeaky?

If you take a pull of air from a helium balloon, you'll sound like a cartoon version of yourself for a few seconds. Learn why helium makes you so high pitched in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,
Lauren bulk bumb Here. Today's question is why does helium
make our voices go all squeaky? And to answer it
we have to ask three other questions. What is air,
what is helium? And what is your voice? Note here
at the top we cannot technically recommend inhaling helium to

(00:24):
play with your voice, and even if we did, you
probably shouldn't take our medical advice. But if you're going
to only pull from a balloon, not a helium tank,
tanks contain compressed gas that will pop your lungs, and
only take short breaths and make sure you get some
good old regular air in between goes so that you
don't suffocate. Okay, So back to our questions. First up, air.

(00:47):
Air is a gaseous molecule soup yep. It seems real thin,
but it's chuck full of stuff when it's dry. Air
is about nitrogen oxygen nearly one percent are gone, and
a wee bit of a bunch of other things carbon dioxide, neon, helium, methane, etcetera.
It can also contain some water, vapor and maybe zero

(01:08):
to three percent. Your voice is the vibration of that
air soup created by sound waves. When you speak, saying,
or yodel, you're pushing air in your lungs out through
your throat past your vocal chords. You can vibrate, loosen,
and pull taught your vocal chords in a number of
ways to make a number of different frequencies of sound.

(01:29):
Because the vibrations are periodic, meaning that their motion is
repeated after an interval of time called a period, the
frequencies produced by your vocal chords are harmonic. The harmonic
frequencies that your vocal chords create are called your voices pitch.
You can manipulate other parts of your mouth noisemaker, your throat, jaw, cheeks,
and tongue to manipulate the way those harmonic frequencies bounce

(01:52):
around inside your head, that is, resonate before they leave
your mouth. This gives more power to the frequencies as
they add to each other, and it creates your voices. Timber.
Timber is one of those great words that's defined by
what it's not. It's not how loud your voices, and
it's not your pitch. It's any other quality that's different.

(02:12):
If two sounds loudness and pitch are the same. Okay,
all of that make more or less sense. On to helium.
Helium is an element that's mixed with a little air
to fill balloons because helium is less massive colloquially termed
lighter than air, and thus makes balloons float in air soup.
It also helps that helium is inert. It doesn't like

(02:35):
reacting with other elements, so it's not likely to cause
an explosion or catch fire or anything else that we
don't like our balloons to do. And it stays a
gas at a wide range of temperatures. But yeah, it's
pretty light. How light are we talking? So light? Helium's
standard atomic weight is just four point zero zero three.
In comparison, nitrogen and oxygen are more than three times

(02:57):
as massive, with standard atomic weights fourteen point zero zero
seven and fifteen point nine nine nine, respectively. So when
you breathe in helium instead of air, you're filling your
lungs and head cavities with these wee atoms that get
pushed around like all heck by sound waves like Oz's
scarecrow in a mosh pit. The atoms that make up

(03:18):
normal air don't oscillate as quickly because they're more massive,
like the tin man in a mosh pit. The practical
outcome of this is that sound waves travel through helium
much faster than they do through air, about three times faster.
Since the sound waves are traveling faster than usual, their
residences inside your head cavities occur at higher frequencies. I

(03:38):
think of it like a pool table if you started
playing with ping pong balls instead of pool balls and
hit them with the same force that fly around the table,
smashing all into each other at much higher speeds. That
means that less residence is happening at the lower end
frequencies of your normal air driven voice, meaning the lower
frequencies have less power to them, meaning that the sounds

(03:59):
that emerge from your head cavities and out of your
mouth are the higher frequencies. You sound squeaky like Donald
Duck Ducks by the way, you get their squeaky quack
by virtue of having a much shorter vocal tract and
less headspace for air than humans. Note that the helium
doesn't change the wavelengths of the sounds emerging from your
vocal cords. It doesn't affect your pitch. If you sing

(04:20):
a particular note on regular air and then on helium
it will be the same note. It will only change
your timber, and specifically the timber of your vowels. Today's
episode was written by Me in the Way Back for
our YouTube series. I hope it wasn't terribly confusing by
a audio, and also that you aren't disappointed that I

(04:42):
didn't suck helium while recording it. It was produced by
Tyler Clang. For more on this and lots of other
resonant topics, visit our home planet, how Stuff Works dot com.