Speaker is an electric device that reproduces sound. Speakers form part of stereophonic sound systems, radios, CD players, and television sets. They also are part of public address systems and equipment used to amplify sound created by musicians.
Most speakers have three main parts: (1) a coil of wire called a voice coil, (2) a permanent magnet, and (3) a cone-shaped piece of paper or plastic called a diaphragm. Waves of electric current from an amplifier pass through the voice coil, producing varying magnetic forces in the coil. The magnetic forces move the coil back and forth within the permanent magnet in rapid vibrations. The diaphragm, which is attached to the voice coil, vibrates with it. The vibrations of the diaphragm produce vibrations in the air. These air vibrations are sound waves.
Some equipment has several speakers, each of which reproduces either lower-pitched or higher-pitched sounds. A speaker that reproduces lower-pitched sounds is a woofer. A speaker that reproduces higher-pitched sounds is a tweeter. In general, a system of woofers and tweeters provides sound reproduction of higher quality than a single speaker. Speakers in such systems are mounted in wooden cabinets. The size and shape of these cabinets can influence the tone quality of the sounds.
