How do we produce our voices?

1. Maya sings into a microphone, and her voice fills the room. A voice needs three things working together: air, a buzz and a shape. Let's look inside.
2. First, the power. The lungs push air up the windpipe. When you just breathe out, the air slips through silently. No push of air, no voice.
3. Next, the buzz. In the voice box are two small folds. To speak, they come together. The air pushes them apart, they spring back, and this happens again and again, hundreds of times each second.
4. Small muscles can stretch the folds. Stretched tight and thin, they vibrate faster, and the note is higher. Loose and thick, they vibrate more slowly, and the note is lower. More air makes it louder.
5. The buzz is not a word yet. It travels through your throat and mouth, and their shape changes its sound. Tongue high and forward: eee. Jaw open: aah. Lips round, tongue back: ooo.
6. Children have short vocal folds, so their voices are high. Grown-ups have longer, thicker folds, so their voices are lower. The size and shape of your throat, mouth and nose make your voice sound like you.

This head and chest are cut open down the middle so you can see inside. Tap each part to see what it does for your voice.

• Lungs. The power for your voice. They push air up the windpipe, and a harder push makes a louder sound.
• Windpipe. The tube that carries air from the lungs up to the voice box.
• Vocal folds. Two small folds inside the voice box. When they come together and air blows through, they vibrate. That buzz is the start of your voice.
• Throat. The space above the voice box. The buzz travels up through it, and its shape helps color the sound.
• Tongue. The busiest shaper of all. Moving it up, down, forward or back changes the space in your mouth, and that changes the vowel.
• Lips. Lips can spread, round or close. Rounding them makes ooo. Closing and popping them makes sounds such as p, b and m.
• Nose. For sounds like m and n, the air and the sound go out through the nose. Pinch your nose and try to hum!

Change the breath, stretch the folds and pick a vowel, or drag the tongue yourself. Watch the folds, the wave and the mouth. Press Hear it to listen.

Experiment: What changes when you stretch the vocal folds tighter but keep the mouth the same?

1. Choose Aah. Slide the fold stretch from loose to tight. Watch the folds and the wave.
2. Keep the stretch the same and try each vowel. Watch the tongue.
3. Move the folds apart to whisper. Then make the breath very gentle.

What we found: The folds set the note and the mouth sets the vowel. Tighter folds vibrate faster and sound higher, but aah stays aah. Moving the tongue and lips changes the vowel without changing the note. With the folds apart there is no buzz, only a whisper, and with too little air there is no sound at all.

Turn on JavaScript to try it yourself.

Each listener asks for a sound: a vowel, a pitch, and loud, soft or whispered. Set the voice machine, then sing it. For 3 stars, get every one right the first time.

Your voice starts with air. When you speak or sing, your lungs push air up the windpipe. At the top of the windpipe is the voice box, a small hollow box you can feel in the front of your neck. Inside it are two soft folds, the vocal folds.

When you breathe, the folds stay apart and the air passes silently. To make a sound, you bring them together. The air pushes them open, they spring shut, the air pushes again, and so on, hundreds of times every second. Each opening lets out a tiny puff of air, and all those puffs make a buzz. Put your fingers on your throat and hum, and you can feel it.

Small muscles change the folds. Stretch them tight and thin, and they vibrate faster, so the note goes up. Let them go loose and thick, and the note goes down. A guitar string does the same when you tighten it. Push more air, and the folds swing wider and the sound gets louder. Children have short folds, so their voices are high. As people grow, the folds get longer and thicker, and voices get lower.

A buzz is not speech yet. On its way out, the sound passes through your throat and mouth, and their shape changes it. A high, forward tongue makes eee. An open jaw makes aah. Round lips with the tongue pulled back make ooo. Lips, teeth and tongue also stop and release the air to make sounds such as p, t and k. Our guitar comparison is not perfect: a guitar's body keeps one shape, but you reshape your mouth many times every second as you talk.

Key words

Vocal folds

Two small folds in the voice box that vibrate when air blows between them.

Voice box

The hollow box at the top of the windpipe that holds the vocal folds.

Pitch

How high or low a sound is. Faster vibrations make a higher pitch.

Hertz

A unit for counting vibrations: one hertz is one vibration each second.

Resonance

When a space, such as your mouth, makes some sounds ring louder than others.

Vowel

A speech sound made with the mouth open, such as eee, aah or ooo.

Check your thinking

1. Where does the sound of your voice start?

   Show the answer

   At the vocal folds, which vibrate as air blows through them. The lungs only supply air. The sound begins where that air sets the vocal folds vibrating.

2. How do you sing a higher note?

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   Stretch the vocal folds tighter, so they vibrate faster. Tighter, thinner folds vibrate faster, and faster vibrations sound higher, just like a tightened guitar string.

3. Why do grown-ups usually have lower voices than children?

   Show the answer

   Their vocal folds are longer and thicker, so they vibrate more slowly. Bigger folds are like thicker, longer strings: they move more slowly, so the note is lower.

4. You say aah, then eee, on the same note. What did you change?

   Show the answer

   The shape of your mouth: the tongue moved up and forward. The note comes from the folds. The vowel comes from the shape of your mouth.

5. What is different about a whisper?

   Show the answer

   The folds stay apart, so there is no buzz, only rushing air. In a whisper the air hisses between folds that are held apart. Your mouth still shapes that hiss into words.

6. In our model, raising the tongue from low to high moves resonance 1 from 950 Hz down to 300 Hz. Which change of vowel is that?

   Show the answer

   From aah toward eee or ooo. A low tongue and open jaw give the high first resonance of aah. A high tongue gives the low first resonance shared by eee and ooo.