The free reed is called free, because unlike the single reed which beats against the rest of its mouthpiece, or the double reed which beats against its twin, the reed is a blade of bamboo or bronze that swings freely to and fro in a closing-fitting frame without beating against anything.
It seems to have been initially an Oriental device, and one question is the possibility of its links with a larger instrument, the trump or jews harp. With both instruments there is a tongue in a close-fitting frame, and today, again in the Orient, both have the tongue cut from a thin sheet of bronze, or slip of bamboo, or other suitable material. The free reed is small enough that it can be made to vibrate by human breath; the jews harp is larger, so that it needs to be plucked by a finger, usually at the hinge end, or by jerking a cord through the hinge end of the instrument, and its vibration and sound are greatly amplified by being blown across its width. Whether one led to the other, we have no evidence. Its origin is unknown – whether in Thailand, or China proper, the Naga territory, or in the border lands between these states we simply do not know.
The free reed is most commonly used, in these same areas, in mouthorgans. A group of pipes, fitted into a common vessel of wood, gourd, metal, etc, each has a reed set in its side at a convenient point to fit into the chamber, and also has a small fingerhole. By closing the fingerhole, the reed is coupled to the air column of the pipe and will then sound. On the more advanced mouthorgans such as the Thai khaen, the Chinese sheng, and the Japanese sho, the sounding length of each pipe is controlled by slots cut in the pipe, which allows the pipes to be arranged in pleasing figurations, where their physical length bears no relation to their acoustical length. The Chinese, for example, say that their shape resembles the phoenix’s wings and the sound the phoenix’s cry, and this shape was copied in Japan. The Thai khaen has its pipes arranged in two parallel rafts, arranged in order of physical length, with the reed-holder about one third of the way up the length, but the sounding length is controlled by slots cut in the bamboo pipes. In other simpler mouthorgans the pipes are arranged just by their physical length.
In some areas, in many parts of the Chinese periphery among the minority peoples, the free reed is cut idioglottally in thin sheet bronze and inserted into a slot cut in the bamboo of the pipe close to the stopped proximal end of a tube, usually of bamboo, with a set of fingerholes. This is against the acousticians’ cant, which assures us that a free reed can sound only a single pitch, based on its length and mass. However their free-reed pipes will sound a series of pitches by opening the fingerholes just as well as any other type of reed-blown pipe. The Karen people in Burma and other minorities also blow side-blown horns, not by the vibration of their lips but via a free reed set into a slot cut in the wall of the horn or of a wooden instrument in the shape of a horn, with a thumb hole in the tip of the horn, for, just as in Africa, theirs is a tonal language in which they can communicate by musical means. The Miao people can also ‘talk’ with pitches from their mouthorgans.
What makes the difference is the shape of the reed and how it lies in its slot. Alan Thrasher has shown that a rectangular reed with the free end cut off square lying flat in its slot when at rest, will produce just one note and it can be sounded by both blow and draw; this is the type used in the Chinese sheng and Japanese sho. If the end is slightly raised from the sides of the slot that same shape of reed will sound only on blow, and if it projects slightly downwards it will sound only on draw; this is the type used in many of our squeeze boxes and harmonicas. But if the reed is cut as a long triangle, coming to a point at the end, as in many such jews harps, then it will generate the air column and allow fingerholes to produce different pitches; this is the bawu and is the type used among the Chinese minorities. And a few Asian mouthorgans have the end of the reed cut in a slant instead of square, and just what does, so far we do not know, but in at least one type it can allow a second not to be obtained from each pipe.
In the mid-eighteenth century a sheng, the Chinese mouthorgan, arrived in St Petersburg, and was there studied and taken apart. Mersenne had also studied a Thai khaen and included it in his great book, Harmonie Universelle of 1636, but it seemed then to have attracted no further interest. It was otherwise in Russia a century later. Organ builders took up the idea and fitted a free reed in some ranks of organs pipes. The idea travelled across Europe and it must soon have been realised, though whether in Russia or further west I do not know, that a free reed does not require a pipe to resonate its sound, any more than a regal had needed pipes, three or so centuries earlier.
The result was all our reed organs, originating in the early years of the nineteenth century, whether blown across the reed like a harmonium or sucked across it like an American organ. This allowed a full-size organ, down to 64-foot stops, to be built into a case no larger than an upright piano. This was followed by all the smaller bellows-blown instruments, concertinas, all the varieties of accordions and button-boxes, and eventually the harmonica, our version of the mouthorgan.
© Jeremy Montagu, 2018