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The sound of music

Go on. Open your mouth and make a sound! What you’re doing to produce vocal sounds and speech is a process known as phonation [foe-nay-shun]. That’s quite a fancy word for something that seems so effortless! Actually it is, thanks to a delicate and complicated system of muscles and strong bands called ligaments. They’re found in your voice box at the front of your neck just below your chin. Collectively known as the larynx, these muscles and ligaments are involved in breathing, sound production and protecting your windpipe from trying to inhale your food.

“Sing until you have no voice
Sing because you have no choice.”
Big Blue Wave by Hey Ocean!

Oh, by the way, you can stop making that racket now.

The larynx consists of a framework of cartilage with surrounding soft tissue. The front part of this cartilage can be easily felt in some necks as the "Adam's apple." The larynx contains your horizontally stretched vocal cords—muscles which are essential for phonation. There is a right and left cord and together they form a "V" when viewed from above.

When you breathe, certain muscles in your larynx keep the vocal cords open; but when you speak or sing, your vocal cords close slightly as you expel air from your lungs. The air passes between the vocal cords.  If you get the air pressure, tension and position of the vocal cords just right, the cords vibrate and produce sounds (phonation).

Sound originates from the vibration of the vocal cords, but other structures are necessary for converting the sound into recognizable speech. The throat, mouth, nasal cavity and sinuses all act as resonating chambers that give the voice its human and individual quality. You produce the vowel sounds by constricting and relaxing the muscles in your throat. Muscles of the face, tongue, and lips help you pronounce (or enunciate) words.

Some singers can reach very high notes and some can reach very low notes.  The pitch (how high or low the note is) of the sound you sing depends on the frequency of vibration of the vocal cords—how many times the vocal cords vibrate per second. Pitch is controlled by the tension on the vocal cords. If they are pulled taut by the muscles, they vibrate more rapidly and a higher pitch results. Decreasing the muscular tension on the vocal cords causes them to vibrate more slowly and produce lower-pitched sounds.

Young boys and girls (prior to puberty) have similar-sounding voices. This is because their larynx  size is very similar, as is the structure of their vocal cords. With the onset of puberty, both male and female voices change as the vocal ligaments become more defined and the cartilage hardens. if you’ve been following Justin Bieber’s career,

You’ve seen this change happen.

Due to the influence of androgens (male sex hormones), vocal cords are usually thicker and longer in males than in females and therefore vibrate more slowly (about half that of an adult female). This is why an adult male’s voice generally has a lower range than that of an adult female. But there’s a lot of variation within that general rule. For a male, Justin Timberlake has a very high voice. For a female, Adele has a low-pitched voice. 

Professional singers learn to control their larynx, regulate their breath and open up the spaces in their sinuses and throats so that they can sing a wide range of pitches. In their hands—or should I say mouths—phonation becomes an art form.

This is just some of the science behind how humans make sound. Science World’s brand new exhibition, AMPED, will be an all-star performance, right at the intersection of art and science. We want to inspire kids to take a deeper look at the mechanics of music and remind adults how music connects us all.

Further Information

Science World Resources | Sound
The mechanism of phonation 
VoiceSource | What creates pitch and loudness?
The Indi-Annas Chorus of Sweet Adelines International | Phonation
Discovery Channel News | The science of singing
eHow | Differences between male and female speech
Wikipedia | Singing