Voice

Voice. Almost all animals have voices. A few animals, like the giraffe, rarely use their voices. But most higher animals can bark, cry, howl, groan, growl, chirp, or make some other noise. Many of the animals use their voices to communicate with each other. Birds can make music with their voices. Dogs can express several feelings with their voices. They whimper when begging or when they feel guilty, they growl when angry, and bark eagerly when they are happy. Several of the zoo animals, such as the chimpanzee, also make various sounds to show different feelings. But no animal's voice is as highly developed as a human being's voice.

The human voice can express ideas through a variety of arrangements of consonant and vowel sounds. It can also be used for singing. It can combine speech with music, and sing words. Because the human voice is so highly developed, people have been able to create elaborate languages. These languages allow people to tell one another their detailed thoughts and actions.

The vocal cords are the main sound producers in human beings. These two small folds of tissue stretch across the larynx (voice box). One fold stretches on each side of an opening in the trachea (windpipe). Muscles in the larynx stretch and relax the vocal cords.

When we breathe, we relax our vocal cords so they form a V-shaped opening that lets air through. When we speak, we pull the vocal cords by the attached muscles, narrowing the opening. Then, as we drive air from the lungs through the larynx, the air vibrates the tightened vocal cords and sound results.

In human beings, sounds of the voice are made chiefly by the vocal cords, small bands of tissue that stretch across the larynx. Muscles in the larynx stretch and relax the vocal cords on each side of an opening in the trachea. When we speak, the larynx muscles pull on the cords, narrowing the opening. Air forced from the lungs vibrates the tensed cords, producing sound.
From The World Book^™ Multimedia Encyclopedia ©1998 World Book, Inc., 525 W. Monroe, Chicago, IL 60661. All rights reserved.
World Book illustrations by Leonard Morgan.

Varying the sound. The voice mechanism is so well organized that we use our vocal cords, muscles, and lungs in many combinations without thinking about it. The more tightly the vocal cords are stretched, the higher are the sounds produced. The more relaxed the cords, the lower the sounds. Even in normal speech we stretch and relax the vocal cords to many degrees. This stretching and relaxing produces variations in the sounds of our voice.

The pitch of the voice is determined by the size of the larynx. Women's voices are usually pitched higher than men's because their vocal cords are shorter. Boys and girls have vocal cords of about the same size until the boys reach puberty. At puberty, the voice boxes of the boys grow larger. As a result, the boys' voices become lower.

The tongue, lips, and teeth also help shape the sounds of the voice. In addition, the nasal cavity gives resonance and color to the voice. When a person becomes ill with a cold and the nasal passages stop up, the person's voice changes.

Straining the voice affects the vocal cords. So does a general muscular tension caused by nervousness. In the disease called laryngitis the larynx is inflamed, irritated, or infected. Sometimes the sick person cannot speak at all for a day or two.

Contributor: Charles W. Cummings, M.D., Prof. and Director, Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins Univ. Medical Center.

Voice

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