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Speaker 1: to brain Stuff from How Stuff Works. Hello brain Stuff.
Speaker 1: I'm Christian Saga, and today we're going to talk about
Speaker 1: the human voice. You might have noticed that if you're
Speaker 1: talking to a group of five year old boys and girls,
Speaker 1: let's say you're asking them for advice about your investment portfolio,
Speaker 1: there's not a big difference between the pitch of the
Speaker 1: girl's voices and the pitch of the boy's voices. Yet,
Speaker 1: if you talk to a group of thirty five year
Speaker 1: old men and women, you notice that the men's voices
Speaker 1: are on average a good bit deeper than the women's voices.
Speaker 1: So why is that and how does it happen? Well,
Speaker 1: first off, let's acknowledge that everyone is a special and
Speaker 1: unique butterfly. And there's no rule about how men and
Speaker 1: women's voices should sound, But on average, adult men's voices
Speaker 1: have what's known as a lower fundamental frequency than adult
Speaker 1: women's voices. The fundamental frequency is simply the scientific term
Speaker 1: for how high or low a person's natural speaking voice sounds.
Speaker 1: Sound frequency is measured in hurts, which is a measure
Speaker 1: of how many times something happens in a second. So
Speaker 1: a sound wave that vibrates a hundred times per second
Speaker 1: produces a tone of a hundred hurts. The more cycles
Speaker 1: per second, the higher the pitch. According to the National
Speaker 1: Center for Voice and Speech, bay bees usually cry at
Speaker 1: a frequency of around five hundred hurts. Children have speaking
Speaker 1: frequencies in the range of two hundred and fifty to
Speaker 1: four hundred hurts. By the time of adulthood. However, men
Speaker 1: have an average fundamental frequency of about one hundred and
Speaker 1: twenty five hurts and women about two hundred hurts. What
Speaker 1: happened here? What why the big difference? Okay, to understand
Speaker 1: why men's voices end up lower than women's voices, we
Speaker 1: need to look at how the body produces sounds. So
Speaker 1: let's take a magical journey to the inside of your neck.
Speaker 1: Leading from your lungs to the cavity behind your mouth
Speaker 1: and nose is a pipeline called the tray chia. You
Speaker 1: use it to breathe. At the top of the tray
Speaker 1: chia is a hollow organ called the larynx, or in
Speaker 1: common parlance, the voice box. The larynx is amazing. For example,
Speaker 1: when you swallow food. It is a part of the
Speaker 1: larynx called the epiglottis that closes off your tra chea
Speaker 1: and keeps you from getting gummy bears in your lungs.
Speaker 1: The larynx is also what allows us to make sound
Speaker 1: for talking or singing. To do this, you use your
Speaker 1: lungs to push a column of air through the larynx
Speaker 1: while using your laryngeal muscles to press together a pair
Speaker 1: of membranes called the vocal folds, or more commonly, your
Speaker 1: vocal chords. When you close the vocal folds like this,
Speaker 1: the air you push out through them makes them vibrate,
Speaker 1: and this vibration leads to sound. So the next time
Speaker 1: you're just shrieking and shrieking until the cashier finally accepts
Speaker 1: your expired coupon, thank your larynx. There are several factors
Speaker 1: that can all have some effect on the fundamental frequency
Speaker 1: of a person's voice, like the size of the larynx
Speaker 1: and the differential development of facial bones and muscles. But
Speaker 1: the most important factor to talk about is the length
Speaker 1: of the vocal folds. If you pluck a string, the
Speaker 1: length of the string affects the frequency of the note
Speaker 1: that plays. Think about a guitar. When you press a
Speaker 1: string down to a higher fret. On a guitar, you
Speaker 1: shorten the length of the part of the string that
Speaker 1: vibrates when you pluck it, and this produces a higher note.
Speaker 1: The same thing happens inside your larynx. The longer the
Speaker 1: vocal fold, the lower the note. During puberty, both boys
Speaker 1: and girls experience growth of the vocal folds, leading to
Speaker 1: lower voices, but the male hormone testosserone, which is released
Speaker 1: by the testicles during puberty, typically causes boys vocal folds
Speaker 1: to grow longer and thicker than girls. On average, adult
Speaker 1: women have vocal folds somewhere around ten millimeters long, while
Speaker 1: adult men have vocal folds in the neighborhood of sixteen millimeters. Consequently,
Speaker 1: women are up there on the upper frets soloing into
Speaker 1: oblivion like a high school kid who just learned how
Speaker 1: to play eruption by Van Halen, and men are letting
Speaker 1: the open strings ring like the intro of Nothing Else
Speaker 1: Matters by Metallica. Now here's some bonus information for you.
Speaker 1: Everyone knows what happens when you inhale some helium from
Speaker 1: a party balloon or you know, straight from an industrial
Speaker 1: helium transport truck. Your voice pitch gets higher. This is
Speaker 1: because helium is less dense than air. But did you
Speaker 1: know you can reverse the effect and give yourself a deep,
Speaker 1: booming bridge troll voice by breathing a gas with a
Speaker 1: higher density than your air, like zenon or sulfur hexafluoride.
Speaker 1: But remember, your body needs air to live, and breathing
Speaker 1: anything other than air can be dangerous, so don't try
Speaker 1: this at home. Check out the brain stuff channel on YouTube,
Speaker 1: and for more on this and thousands of other topics,
Speaker 1: visit how stuff works dot com.