musical instruments are classified in various ways, but the system devised in 1914 by Kurt Sachs and E. M. von Hornbostel has been accorded recognition by both anthropologists and musicologists because it is applicable not only to modern Western instruments but to primitive and exotic instruments as well. This system divides instruments into five main classes: idiophones, membranophones, aerophones, chordophones, and electrophones. Most idiophones, which are instruments made of a sonorous material needing no additional tension, and membranophones, whose sound is produced by the vibrations of a membrane stretched over a hollow resonator, are popularly grouped as percussion instruments; certain instruments, however, such as the jew's-harp and the glass harmonica (see harmonica2), are idiophones, but are not percussion instruments. Aerophones are of two types: free aerophones, which include those reed instruments employing free reeds, and wind instruments, which produce sound by means of an enclosed, vibrating column of air. Chordophones are stringed instruments. Electrophones, a development of the 20th cent., are of two types: those which simply add an electric amplifier to some existing instrument, e.g., the piano, guitar, or reed organ, and those whose sounds originate as electrical vibrations, e.g., the electric organ. Musical instruments are of very ancient origin; the remains of flutes dating to at least 35,000 years ago have been found in SW Germany. See articles on individual instruments, e.g., dulcimer.
See K. Sachs, The History of Musical Instruments (1940); K. Geiringer, Musical Instruments (1943, 2d ed. 1978); A. Buchner, Musical Instruments: An Illustrated History (rev. ed. 1973).