A Dictionary of Music and Musicians/Free Reed
FREE REED. Organ stops of the Free-reed class are more frequently made by continental than by English artists. The sound-producing part of a pipe of this species is formed thus:—A surface of metal or wood has a vertical opening made through it as a passage for the wind: in front of this a strip or tongue of metal—in some large examples wood—is adjusted, fastened at the upper end and left at liberty at the lower, which is so slightly smaller than the opening as almost exactly to fit into it. This tongue is by the current of air carried a short way through the opening, when it springs back from its own elasticity; and the sound results from the periodical and regular beats which the tongue, vibrating to and fro, imparts to the passing air. The 'vibrators' of a harmonium are really free reeds; but in the case of an organ-pipe the tongue is furnished with a tube, which, upon the principle of a speaking-trumpet, greatly augments and amplifies the sound produced. There are some free-reed 16- and 32-feet posaunes in the pedal organ of Schulze's fine instrument at Doncaster parish church.
[ E. J. H. ]