Cristen explains why male humans' voices generally get lower than female humans' during puberty.
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Hello, Brainstuff! 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 butterknife, 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 times 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 of 250 to 400 hertz.
By the time of adulthood, however, men have an average fundamental frequency of about 125 hertz, and women about 200 hertz. What happened here? Why the big difference?
To understand why men’s voices end up lower than women’s voices, we need to look at how the body produces sound. So let’s take a 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 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.”
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 cords.
When you close the vocal folds like this, the air you push out through them makes them vibrate, and this vibration leads to sound.
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 differential development of facial bones 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 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 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 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, while adult men have focal folds in the neighborhood of 16 millimeters.
Consequently, women are up there on the upper frets 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. Y’know? Y’know?
Bonus! 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 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 potentially be dangerous, so we don’t recommend trying this at home.