The voice

With the season about to tilt from summer to autumn, Canada geese are once more filling the air with their melodious sounds as they prepare to fly south for the winter.

To us, of course, the sound of a flock of geese “talking” to each other is more or less the same as the sound of a downtown street corner during a traffic jam, but all that honking must mean something, mustn’t it?

Well, yes, it must, but not in the way we think of sounds having meaning. Geese honk, dogs bark, cats meow and cows moo, but only humans (as far as we know) use sound to communicate abstract ideas rather than immediate emotional states. It’s one of the few things that distinguishes us from the other animals.

Physiologically, there are four major functions that must be coordinated for us to speak: breathing, phonation, resonance and articulation.

Speaking starts with the exhalation of air. We do that all the time without thinking about it, but even such a simple-seeming activity is a marvelous combination of actions by the abdominal muscles to force the diaphragm up and the ribcage inward. How forcefully that happens determines how much and how rapidly air is expelled, which plays an important role in determining the volume and duration of the sound.

Phonation, the process of actually making a sound, happens in the larynx, a muscular tube that contains the vocal cords, two folds of mucous membrane with a gap between them called the glottis. Each fold encloses an elastic vocal ligament. Muscles tighten the cords as air is forced up through the glottis, which causes the cords to vibrate, producing sound.

In normal breathing the vocal muscles are slack, so that the air passes silently in and out through a wide slit. The tighter the muscles contract the vocal cords, the higher the pitch of the sound, just as a tight guitar string produces a higher pitch than a loose one.

The vocal cords in a grown man are longer and thicker than those in a woman, which is why most men have deeper voices than most women (Michael Jackson excepted). Pitch is determined by the frequency at which the vocal cords vibrate. One hundred vibrations per second produce the low chest sound of the male voice, while 1,000 per second produce the high C of a trained soprano.

One of the physical variations that effects a person’s natural tone of voice is resonance. Resonance also amplifies the sounds being produced. It involves the pharynx (throat), the mouth, the nose, the nasal sinuses and the chest cavity. Just like banging on a steel drum sounds different than banging on a tin can, so differences in the size and shape of these resonating areas produces different noises in different people.

A nasal voice, for example, is produced when most of the resonance is taking place in the small nasal cavities, while a deep radio-announcer’s voice is produced in the big chest cavity.

Finally, speech involves articulation, the process of forming sound into words. This involves complex maneuvers with the lips, tongue, soft palate and facial muscles.

Speech disorders afflict almost one out of 10 people in North America. Forty percent are caused by hearing loss: we control our voices based on the feedback we get from our ears. When we can’t hear, it becomes much harder to accurately judge the sounds we are forming or how loud they are. Another 10 percent are due to neurological disease, and the rest to a range of other causes, from emotional disturbance to genetic defects that affect the shape and size of some of the structures used in speaking. Dyslalia, for example, better known as lisping, can result from an abnormality in the tongue or shape of the mouth, and dysphemia–stuttering–is thought to be caused by neurological deficiencies present at birth or caused by injury.

It doesn’t take much to affect speech, because, as you can see, it’s an amazingly complicated process–so complicated you’d think it would take so much concentration we’d have trouble saying a word. But in fact, quite amazingly, we’re able to blabber on without even thinking about what we’re saying.

In fact, we can even talk with one foot in our mouth.

Let’s see those noisy geese do that.

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