BrainStuff Classics: Why Do Men Have Deeper Voices?

Of course, everybody's voice varies, but in general male humans develop lower-pitched voices than female humans starting around puberty. Learn why in this classic episode of BrainStuff. 

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,
I'm Lauren voc Obam, and today's episode is another brain
Stuff classic from our erstwhile host, Christian Sager. Our question
for the day, why do men tend to have deeper
voices than women? Hello, brain Stuff, I'm Christian Saga, and

(00:23):
today we're going to talk about the human voice. You
might have noticed that if you're talking to a group
of five year old boys and girls, let's say you're
asking them for advice about your investment portfolio, there's not
a big difference between the pitch of the girl's voices
and the pitch of the boys voices. Yet if you
talk to a group of thirty five year old men

(00:44):
and women, you notice that the men's voices are on
average a good bit deeper than the women's voices. So
why is that and how does it happen? Well, first off,
let's acknowledge that everyone is a special and unique butterfly,
and there's no rule about how men and women's voices
should sound. But on average, adult men's voices have what's

(01:07):
known as a lower fundamental frequency than adult women's voices.
The fundamental frequency is simply the scientific term for how
high or low a person's natural speaking voice sounds. Sound
frequency is measured in hurts, which is a measure of
how many times something happens in a second. So a

(01:27):
sound wave that vibrates a hundred times per second produces
a tone of a hundred hurts. The more cycles per second,
the higher the pitch. According to the National Center for
Voice and Speech, babies usually cry at a frequency of
around five hundred hurts. Children have speaking frequencies in the
range of two hundred and fifty to four hundred hurts

(01:48):
by the time of adulthood. However, men have an average
fundamental frequency of about one hundred and twenty five hurts
and women about two hundred hurts. What happened here? What?
Why the big difference? Okay, to understand why men's voices
end up lower than women's voices, we need to look
at how the body produces sounds. So let's take a

(02:09):
magical journey to the inside of your neck. Leading from
your lungs to the cavity behind your mouth and nose
is a pipeline called the tray chia. You use it
to breathe. At the top of the trachea is a
hollow organ called the larynx, or in common parlance, the
voice box. The larynx is amazing. For example, when you
swallow food, it is a part of the larynx called

(02:31):
the epiglottis that closes off your tray chia and keeps
you from getting gummy bears in your lungs. The larynx
is also what allows us to make sound for talking
or singing. To do this, you use your lungs to
push a column of air through the larynx while using
your laryngeal muscles to press together a pair of membranes
called the vocal folds, or more commonly, your vocal chords.

(02:54):
When you close the vocal folds like this, the air
you push out through them makes them vibrate, and this
vibration leads to sound. So the next time you're just
shrieking and shrieking until the cashier finally accepts your expired coupon,
thank your larynx. There are several factors that can all
have some effect on the fundamental frequency of a person's voice,

(03:17):
like the size of the larynx and the differential development
of facial bones and muscles. But the most important factor
to talk about is the length of the vocal folds.
If you pluck a string, the length of the string
affects the frequency of the note that plays. Think about
a guitar. When you press a string down to a
higher fret. On a guitar, you shorten the length of

(03:39):
the part of the string that vibrates when you pluck it,
and this produces a higher note. The same thing happens
inside your larynx. The longer the vocal fold, the lower
the note. During puberty, both boys and girls experience growth
of the vocal folds, leading to lower voices, but the
male hormone testosserone, which is released by the testicles during puberty,

(04:01):
typically causes boys vocal folds to grow longer and thicker
than girls. On average, adult women have vocal folds somewhere
around ten millimeters long, while adult men have vocal folds
in the neighborhood of sixteen millimeters. Consequently, women are up
there on the upper frets, soloing into oblivion like a
high school kid who just learned how to play eruption

(04:24):
by Van Halen, and men are letting the open strings
ring like the intro of nothing else matters by Metallica.
Now here's some bonus information for you. Everyone knows what
happens when you inhale some helium from a party balloon
or you know, straight from an industrial helium transport truck.
Your voice pitch gets higher. This is because helium is

(04:45):
less dense than air. But did you know you can
reverse the effect and give yourself a deep, booming bridge
troll voice by breathing a gas with a higher density
than your air, like zenon or sulfur hexafloor a ride.
But remember, your body needs air to live, and breathing
anything other than air can be dangerous, so don't try

(05:06):
this at home. Today's episodes written by Joe McCormick and
produced by Tyler Clang. If you miss Christian you can
find him on his new pop culture podcast super Context,
And of course, for more on this and lots of
other deep topics, visit our home planet, how Stuff Works
dot com.