Ralph Saca, age 16, of Sarasota, Fla., for his question:

HOW DOES A RECORDING MICROPHONE WORK?

A sound recording microphone is very much like the human ear. It is made up of a thin and sensitive membrane which vibrates at the frequency with which the sound waves strike it and responds directly to the strength of the sound.

Vibrations of the metal membrane produce an electric current which alternates, or vibrates, at the frequency and with the strength of the sound. The current is then amplified in strength and sent on to the sound recording machine.

A studio microphone works on almost the same principle as that used in the telephone, except that the studio equipment is much more sensitive.