Human Speech

It takes an interaction of 72 different muscles to produce human speech.

The speech skill is a wonder. To produce a phrase, about 100 muscles of the chest, neck, jaw, tongue and lips must collaborate. Each muscle is a bundle made of hundreds or thousands of fibers. For the coordination of these muscles much more neurons than necessary are required for contracting the muscles from an athlete’s feet. Just one motor neuron can trigger movement in the 2,000 muscular fibers existent on a calf muscle. But the neurons controlling the vocal cords or the larynx can be bound just one to two-three muscle cells.

Each spoken word or short phrase is accompanied by its own pattern of muscular movements. All the information necessary for speaking a phrase like “How are you?” is stored in the brain, in the speech area. But it’s not about a fixed program. If you have a mouth wound impeding you to pronounce the words like you usually do, the movements are modified, allowing you to utter the words as closely as possible to normal.

A simple “Hallo” can transmit a lot of things. The voice’s tone shows if the speaker is happy, pleased, bored, hurried, angry, sad, scared, aggressive or dominant and the intensity of these states; irony, affection, support or joke. The sense of a simple expression can be changed according to the rapidity of the movements and the fractions of seconds depending on how much the movement of different muscles lasts.

Humans can emit about 14 seconds per second, while isolated parts of the speech apparatus, like tongue, lips, jaws and others cannot execute more than 2 movements per second.

Early humans could have had a rudimentary speech system of visual, tactile and auditive calls, resembling animal communication. Speech appeared when we acquired the ability of representing objects through symbols and communicate to another individual our own mental creations. Our special brain enabled us to do this.