Of all the living beings only man can express himself in words. He is able to produce different types of sounds. Do you know how human beings produce sounds?
Our throat has a hollow organ called the ‘sound box’ or ‘larynx’. It is, in fact, an enlarged part of the wind pipe. Its walls are made of cartilages and are lined with mucous membrane inside. The cartilage is made up of a very soft bony substance. The outer portion of our ears is also made up of this material. There are two vocal cords on the two sides of this box. Their movement is controlled by sixteen muscles. When air from the lungs passes through the vocal cords, they start vibrating. As a consequence of these vibrations, sound is produced.
The sharpness, hoarseness and sweetness of sound depend upon the tension of the vocal cords. And this is controlled by the muscles. When the vocal cords are under higher tension, they can vibrate up to 1000 times per second, thus producing melodious sounds. In fact, more the number of their vibrations, sharper is the sound; and less the number of vibrations, the heavier is the sound. The rate of vibrations varies from person to person. That is why the pitch of sound is also different in different people. People with melodious voices have a better formed sound box as compared to others.
When the child attains the age of 13-14 years, his vocal cords become thicker, as a result of which their frequency of vibrations is reduced. This lowers the pitch of the voice. Not only this, even our chest, stomach, tongue, lips, teeth, etc., are also involved in the production of sound.