a loudspeaker that radiates sound waves with a high degree of directivity by using a horn to concentrate the flux of acoustic power in a specific direction. The horns used usually have a cross-sectional area that varies exponentially. In order to transmit the low frequencies of a sound spectrum properly (without distortion), a horn’s cross section must expand slowly, which increases the length. Consequently, small horn loudspeakers, which are widely used, can only reproduce higher frequencies.
Horn loudspeakers are divided into two types, depending on the structural design. In the first type, sometimes known as a large-throat horn, a cone-shaped dynamic loudspeaker is loaded by a horn having a throat (the input opening) with an area similar to the area of the base of the loudspeaker cone. In the second type, often called a small-throat horn, the dynamic loudspeaker used has a rigid diaphragm several times greater than the size of the throat.
The operating frequency range of a horn loudspeaker depends on the intended use and may cover either a small portion of the acoustic frequency spectrum or a comparatively wide band (approximately 100 to 6,000 hertz). Loudspeaker powers are usually from 5 to 100 volt-amperes. Because of their high efficiency (up to 20 per cent), horn loudspeakers are used either as a self-contained unit or as a part of a loudspeaker system in sound systems for streets, squares, and motion-picture theaters and in other large premises.
N. T. MOLODAIA and L. Z. PAPERNOV