(classical orchestra intro music)
(writing on chalkboard)
(beep)
- Hello, Brain Stuff!
I'm Cristen, and today we're going to talk
about the human voice.
First off, let's acknowledge that everyone
is a special and unique butter knife,
and there's no rule
about how men and women's
voices should sound.
But on average, adult men's
voices have what's 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 is.
Sound frequency is measured
in hertz, which means
how many times something
happens in one second.
So a sound wave that
vibrates 100 per second
produces a tone of 100 hertz.
The more cycles per second,
the higher the pitch.
Babies usually cry at a
frequency of around 500 hertz.
Children have speaking frequencies
in the range 250 to 400 hertz.
By the time of adulthood, however,
men have an average fundamental frequency
of around 125 hertz, and
women about 200 hertz.
So what happened here?
Why the hertz gender gap?
Leading from your lungs to the cavity
behind your mouth and nose
is a pipeline called the trachea.
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.
There are several factors
that can all have some effect
on the fundamental frequency
of a person's voice,
like the size of the larynx and
the differential development
in facial bone and cavities in the head.
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 that note plays.
Think about a guitar.
When you press a string down
to a higher fret on a guitar,
you shorten the length
of the part of the string
that vibrates when you pluck it.
And this produces a higher note.
Same thing happens inside your larynx.
During puberty, both boys and girls
experience growth of the vocal folds,
leading to lower voices.
But the male hormone testosterone,
which is released by the
testicles during puberty,
typically causes boys' vocal folds
to grow longer and thicker than girls'.
On average, adult women have vocal folds
somewhere around 10 millimeters long.
Not bad, ladies!
While adult men have vocal folds
in the neighborhood of 16 millimeters.
Consequently, women are
up there on the upper fret
soloing into oblivion,
like a high school kid
who just learned to play
"Eruption" by Van Halen!
And men are letting the open strings ring
like the intro to "Nothing
Else Matters" by Metallica.
You know?
You know?
Bonus fact: 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 less dense than air.
But did you know you
can reverse the effect
and give yourself a deep,
booming, bridge troll voice
by breathing in a gas with
a higher density than air,
like xenon, or sulfur hexafluoride?
But remember, your body needs air to live,
and breathing anything other than air
can be potentially dangerous,
so we don't recommend trying this at home.
