A type of Reed consisting of a flexible metal tongue, fixed at one end to a stationary plate. When activated by air pressure or suction, the tongue vibrates freely through a slot cut in the plate (in some cases the reed is cut out of the plate and lies flat within it). This contrasts with a ‘beating reed’ such as an organ reed-pipe tongue or clarinet reed, which beats against a flat surface having an aperture cut into it that is narrower than the tongue. Each free reed gives only one note, a different reed being required for each note of the instrument. However, since the reed is free to vibrate with varying degrees of amplitude in response to the amount of air pressure used, free reed instruments are nevertheless capable of dynamic inflection. The pitch of the note is produced by the natural frequency of the reed, either alone (as with the harmonica), or in some cases (see Sheng) in a coupled system combining the frequencies of both reed and pipe (in the manner of beating reed instruments). Timbre can be affected by the shape and design both of the reed itself and of the resonating chamber. The principle of the free reed has existed for many centuries in East Asia but was not extensively used in the West until the late 18th century, when it began being applied to organs.
For further discussion of free reeds see Accordion; Concertina; Harmonica; Organ, §III, 3; Reed instruments; and Reed organ. Other free reed instruments entered in this dictionary include the khaen, keledi, mouth organ, saenghwang and shō.
BARBARA OWEN, RICHARD PARTRIDGE