The human larynx

From the noble soliloquy to the humble grunt, the voice is a versatile tool which you control using what is colloquially called the voice box, or more formally, the larynx.

The voice is made of a handful of cartilages and muscles inside your throat. You can find it easily by feeling for your thyroid notch, sometimes called an Adam’s apple. Everyone has one, but it tends to be more prominent in men, hence the gendered name. Try alternating back and forth between the sounds /s/ as in Snake and /z/ as in Zebra. You should feel a vibration which switches on for /z/ and off for /s/. This is your voice.

We use this mechanism to convey an astonishing amount of information. Some fixed aspects of the voice convey something about you as a person, such as your height, sex, and possibly your physical attractiveness. But the voice is also flexible and it sings our favourite songs, distinguishes between voiced and voiceless phonemes so that you can separate words like “singer” from “zinger”, encodes the tones of tonal languages which will be unfamiliar to most speakers of European languages but are a prominent feature of two thirds of the worlds languages, stresses syllables so that a DESert is a place that is very dry while to desERT is to leave someone high and dry, emphasises words so that “THEY don’t like them” means something subtly different than “they don’t like THEM”, and expresses a range of uncertainty from questions to commands.

We accomplish all of this by controlling two fleshy membranes called the vocal folds that sit in the airway. We can set them out of the way so that air flows normally and we can breathe deeply. Or we can press them together tightly so that air passing between sets them to vibrating like air flowing over a wax-paper comb-kazoo. This vibration is the physical basis for your voice. We can stretch the vocal folds thin and taught so that they vibrate at a high frequency, or relax them so that they vibrate at a low frequency. This is how you control the pitch of your voice, and these laryngeal acrobatics are the driving force behind a whole range of expressive subtleties.