Why don’t people have identical voices?

          No two persons in the world have exactly the same voice! Do you know why it differs from person to person?

          The act of speaking involves movements of hundreds of muscles in split-second co-ordination. The speech organ called larynx or voice-box is capable of producing an infinite number of sounds. It is part of the throat through which air passes. When we breathe, air passes through the larynx downwards through mouth and nose into trachea (windpipe) and finally to the lungs.

          The larynx is made up of a tough wall of cartilage. It’s inside lining has two folds of tissue stretching on each side and leaving a gap between them. These are called vocal cords. In case of simple breathing, the gap between the cords remains wide open. The cords are slack. But talking, singing or shouting involves tightening of the cords. The exhaled air causes the cords to vibrate and produce sound. Our vocal cords can be found in any of about 170 different positions.

          If the vocal cords are slack, they may vibrate about 80 times per second and the result is deep tones. If they are tensed, they vibrate rapidly, perhaps thousand times a second, and produce short sound waves or high tones or high pitch sounds.

          As a child has short vocal cords, they produce short air waves and consequently a high pitched voice. As a child grows, the vocal cords become longer and that causes the voice to become deeper. Thus the voices of adults are heavier and deeper than children’s voices.

          Similarly the voices of most adult men are deeper than those of women. This is because a man’s larynx is larger than that of a woman with longer cords.

          The pitch of a voice depends upon the length of the vocal cords. Each voice has a certain range of frequencies. It is this range that determines what kind of voice a person has. Voices can be divided into six groups: bass, baritone, and tenor for men; and alto, mezzo-soprano and soprano for women.

          The quality of human voice also depends on many other things, such as resonating spaces, lungs, nasal cavities etc. The nose, sinuses, pharynx and the oral cavity act as resonating chambers, and modify the vocal tone produced by the vocal cords. The movement of the tongue against palate, the shaping of the lips, and the arrangement of teeth also produce changes in the voice.

           Since the structures and movements of all these organs are different in different persons the voices of no two persons in the world can be the same.