Why Do Voices Crack During Puberty?
Few sounds are as instantly recognizable as a teenager's voice breaking mid-sentence. The squeak is not nerves or carelessness. It is the sound of the voice box being physically rebuilt while it is still in daily use.
The larynx grows, the folds stretch
The voice starts at the vocal folds, two bands of tissue in the larynx whose vibration sets the pitch of every sound we make. At puberty, testosterone drives the larynx to grow, and the folds lengthen and thicken. Voice research gives the numbers: by about age sixteen, male vocal folds measure roughly 18 to 24 millimetres and vibrate near 130 Hz, while female folds stay around 15 to 20 millimetres near 220 Hz. The folds also gain a third tissue layer during these years. Longer, heavier folds vibrate more slowly, and slower vibration is exactly what a deeper voice is.
The pitch drops suddenly, not smoothly
A long-running study that followed boys through puberty found the speaking pitch does not glide downward gently. It drops abruptly in late puberty, tracking the physical stages of development. The larynx grows in spurts, so the instrument changes size in steps rather than millimetre by millimetre.
Why the crack happens
Pitch control is a skill run by the brain, which learned its settings on a child's larynx. When the folds suddenly get longer and heavier, the old settings no longer hold: the brain aims for one note, the new instrument produces another, and the voice flips unpredictably between them. That flip is the crack. As the brain recalibrates to the adult larynx over the following months, the flips fade and the new, lower register stabilizes.
Everyone changes, some more noticeably
Girls' voices also change at puberty, just less dramatically, since their folds grow less. The change in boys is large enough that researchers use "age at voice break" as a convenient marker of puberty timing in large genetic studies, and those studies show its timing is strongly influenced by genetics. The squeaky months, embarrassing as they feel, are simply what it sounds like when a body part grows faster than the skill that runs it.
Facts checked: 22 October 2026
Sources: Harries, M. et al. (1997). Changes in the male voice at puberty. Archives of Disease in Childhood, 77(5):445-447. PMC1717378. Pedersen, M., Jonsson, A. O., and Larsen, C. F. Genetics and voice production in childhood and adolescence - a review. PMC9152557.