Dear Bianca,

Think about all the ways you use your voice: talking, singing, whispering, shouting, yodeling. Humans make so many sounds with just their voices.

I talked about how it works with Alisa Toy. She’s a professional singer who teaches in the School of Music at Washington State University.

She told me that the human voice is the smallest instrument in the world. The parts that make the sound—called the vocal folds or vocal cords—are about as long as your thumbnail.

So, where are those tiny vocal folds and how do they do it?

Inside your throat you have two tubes. The esophagus is the food tube. That’s how food travels from your mouth to your stomach. The trachea is the air tube. It’s how air moves between your mouth and lungs.

Your larynx—also called the voice box—sits right on top of your trachea. The larynx’s job is to close off that air tube while you’re eating. That keeps your food from accidentally going down the wrong tube.

The larynx also houses the vocal folds that make sound.

“The vocal folds are in the middle of the larynx,” Toy said. “Air that’s pumped up from the lungs causes them to vibrate—and that’s where the sound comes from.”

A diagram of a human showing a side profile with mouth and nasal cavity and the larynx, vocal cords and other structures
All the parts that contain -glottis (inside the blue box) are parts of the larynx. The vocal folds (vocal cords) are tucked right in the middle. Image: NIH/Alan Hoofring, blue box added by Dr. Universe

The vocal folds are tiny, but they’re also incredibly thin. Try gently pinching your eyelid. Your vocal folds are even thinner than that.

The vocal folds sit next to each other. When you breathe, the space between the vocal folds is slightly open. The air whooshes from your lungs and up through the opening. That vibrates the vocal folds.

Toy told me that when the vocal folds vibrate, the sound isn’t like your regular voice. It sounds like clicks.

To transform those clicks into your actual voice, you need resonance. That’s the way the waves of sound change as they bounce around the open spaces inside your head. That means inside your mouth, behind your nose and in the back of your throat.

You might not realize it, but you make lots of little adjustments in your throat and mouth when you use your voice. Singers like Toy work hard to fine tune those adjustments to make beautiful sounds.

When you sing or talk, you also adjust how you hold your tongue and lips in relation to things that don’t move—like your teeth or the hard part of the roof of your mouth. Now, the clicks from your vocal folds have transformed into musical notes and words.

Scientists are trying to figure out when humans began to talk. One clue is that there’s a direct connection between your brain and your larynx. Other animals don’t seem to have that.

Being able to talk, shout or yodel in the dark and across distances would have been super useful for early people. Maybe it helped make humans a re-sound-ing success.


Dr. Universe