Human beings have the capacity to express themselves through words. Man is able to produce different types of sounds. Do you know how this is possible? Our throat has a hollow organ called the ‘sound box‘ or ‘larynx‘. It is, in fact, an enlarged part of the windpipe. 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. Sixteen muscles control the movement of the two cords. When air from the lungs passes through the vocal cords, they start vibrating. As a result of these vibrations, sound is produced. The sharpness, hoarseness and sweetness of sound depend upon the tension of the vocal cords. And the muscles control this tension. 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 the vibrations, sharper is the voice and less the number of vibrations, the heavier is the voice. 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 the 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.