..... Click the link for more information. . The vibrations create sound waves in the air around the speaker. In a dynamic speaker, the most common kind, the diaphragm is cone-shaped and is attached to a coil of wire suspended in a magnetic field produced by a permanent magnet. A signal current in the suspended coil, called a voice coil, creates a magnetic field that interacts with the already-existing field, causing the coil and the diaphragm attached to it to vibrate. To provide a faithful reproduction of music or speech, a loudspeaker must be able to reproduce a wide range of audio frequencies (i.e., 20 Hz to 20 kHz). Since it is difficult for a single speaker to do that adequately, many quality sound systems employ speakers of three different sizes. The largest ones, or woofers, reproduce low frequencies; the medium-sized ones, or midrange speakers, reproduce middle frequencies; the smallest ones, or tweeters, reproduce high frequencies. The three sizes were traditionally contained in the same cabinet, with a pair of such speakers used for stereophonic sound stereophonic sound, sound recorded simultaneously through two or more electronic channels. For live recordings, microphones are placed in different positions relative to the sound source.
..... Click the link for more information. , but increasingly in the late 1980s and early 1990s home sound systems used smaller pairs of speakers enclosures containing only the midrange speakers and tweeters and a single woofer cabinet designed to be placed in an out-of-the-way location. This design takes avantage of the fact that the human ear is not good at determining the direction of low-frequency sound, and thus stereo perception is not adversely affected by the location of the woofer. A crossover network is a filter in a speaker system that ensures that each speaker receives only signals in the frequency range it is designed to reproduce. A properly designed enclosure can reduce unwanted resonances and extend the frequency range of a speaker system. Along with dynamic speakers, other speaker types include electrostatic and piezoelectric.
loudspeaker
or speaker)
loudspeaker
loudspeaker [′lau̇d‚spēk·ər]
Loudspeaker
an electroacoustic or mechanical device for the loud reproduction of speech. music, and other sounds. Most types of loudspeakers transform electrical current or the voltage of sound frequencies into sound vibrations of the surrounding air medium with the aid of a mechanical movable system (diffuser. diaphragm). There are different types of loudspeakers. including the moving-coil. the horn. the piezoelectric. the condenser. and the magnetic. In the past pneumatic loudspeakers were also used. The direction in which a loudspeaker operates is determined by a horn (in moving-coil and pneumatic loudspeakers) and by the use of sound columns.
The most frequently used devices in broadcast receivers and sound amplification systems are moving-coil loudspeakers with a rated capacity of 0.1 to 100 watts (W) and a band of reproduced frequencies of 50 to 12.000 hertz (Hz); sound columns consisting of several diffuser loudspeakers with total rated capacity of up to 100 W and a band of reproduced frequencies of 100 to 8,000 Hz; and loudspeaker systems consisting of moving-coil and horn-type loudspeakers with a total rated capacity of up to 100 W.
REFERENCES
Dreizen. I. G. Elektroakustika i zvukovoe veshchanie. Moscow, 1961.Dol’nik, A. G. Gromkogovoriteli. 3rd ed. Moscow-Leningrad, 1961.
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