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Michael: So you’re about to give a big presentation in front of a ton of people. You start off strong, but in the middle of a sentence, your voice refuses to cooperate. In a blaze of awkward glory, your voice completely cracks, its pitch wavering uncontrollably. If it’s any comfort, this happens to pretty much everyone at some point.

And usually, it’s because of puberty, stress, or illness. Your voice mainly comes from your larynx, or voicebox. The inside lining of your larynx has two flaps of tissue stretching on each side with a gap between them.

Those are your vocal folds. When you breathe, your vocal folds open to let air through, but when you speak, they close. And when you talk, sing, or yell, air is blown up from your lungs and past the edges of your closed vocal folds, which vibrate to produce your voice.

The position of your vocal folds determines your voice’s pitch, and they can be in any of about 170 different positions. Kids have higher-pitched voices because they have shorter vocal folds than adults. When you hit puberty, your vocal folds lengthen and thicken, and you end up with a deeper, lower adult voice. It’s like how the longer a guitar string is, the lower its note will be. The sudden growth of the voicebox makes it difficult for the vocal folds to maintain steady vibrations, so the voice cracks a lot during this transitory phase.

Another reason your voice cracks during puberty has to do with muscle memory. Your vocal folds might automatically go for a pitch that you used to be able to reach, but now can’t — so instead you get all squeaky. Usually male puberty involves much more larynx growth than female puberty, so there’s a lot more voice cracking in the process.

But what about people who aren’t experiencing the raging hormones of adolescence? In most cases, adult vocal cracking has to do with stress or illness. When you’re anxious, your vocal folds tend to tense up and your ability to control them shoots down. Also, people tend to forget to take deep breaths in stressful situations. Without a strong breath, there may not be enough pressure against the folds to push out a strong voice.

Combine that with a dry mouth and throat, and you have a recipe for very shaky vocalizing. Frequent shouting, screaming or straining can cause also make your voice crack because the vocal folds get inflamed. In extreme cases, people can even develop nodules—hard, callous-like growths that become larger and stiffer over time if they keep straining their voice. Inflammation and nodules lead to some serious crackage by altering or blocking your airflow.

When you get a bad cold, your voice cracks because your vocal folds are irritated from symptoms like coughing and sneezing. Plus, your body's natural healing process makes vocal tissues thicker than normal and also causes cracking — sometimes long after an illness has passed. Basically, if your voicebox is disturbed in any way, you’re probably gonna start sounding like Shaggy from Scooby-Doo.

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