Yesterday, your son sounded like he's always sounded — like a boy. But today,
you heard that first crack in his voice. He's started puberty and several things about
him are changing. Along with obvious changes in physical appearance, his voice will
start sounding a whole lot different. For a while, he might have difficulty controlling
it and he'll make all sorts of odd noises when speaking.
The Changing Larynx
It's the larynx (or voice box) that's causing all that noise. As the body goes
through puberty, the larynx grows larger and thicker. It happens in both boys and
girls, but the change is more evident in boys. Girls' voices only deepen by a couple
of tones and the change is barely noticeable. Boys' voices, however, start to get
significantly deeper.
The Science Behind the Squeaking
The larynx, which is located in the throat, plays the major role in creating the
sound of the voice. Two muscles, or vocal cords, are stretched across the larynx and
they're kind of like rubber bands.
When a person speaks, air rushes from the lungs and makes the vocal cords
vibrate, which in turn produces the sound of the voice. The pitch of the sound produced
is controlled by how tightly the vocal cord muscles contract as the air from the lungs
hits them. If you've ever plucked a small, thin rubber band, you've heard the high-pitched
twang it makes when it's stretched. A thicker rubber band makes a deeper, lower-pitched
twang. It's the same process with vocal cords.
Before a boy reaches puberty, his larynx is pretty small and his vocal cords are
kind of small and thin. That's why his voice is higher than an adult's. But as he
goes through puberty, the larynx gets bigger and the vocal cords lengthen and thicken,
so his voice gets deeper. Along with the larynx, the vocal cords grow significantly
longer and become thicker. In addition, the facial bones begin to grow. Cavities in
the sinuses, the nose, and the back of the throat grow bigger, creating more space
in the face — which gives the voice more room to resonate.
As a boy's body adjusts to this changing equipment, his voice may "crack" or "break."
This process lasts only a few months. Once the larynx is finished growing, your son's
voice won't make those unpredictable sounds.