What are multiphonics? How can you play two notes at a time on a woodwind instrument?
Let’s use the flute as an example, but the principle is similar for all woodwinds. In a ‘normal’ note played on a woodwind instrument, especially in the low range, all (or nearly all) of the tone holes downstream of a certain point are open, and all those upstream from that point are closed. The pipe behaves approximately like a pipe that stops near the first open hole. (For more detail, see tone holes on our introduction to flute acoustics.) Multiphonics are usually produced by opening a single tonehole, usually a small one, somewhere in the line of closed tone holes, but not at 1/2 or 1/3 of the way along the pipe. (At these positions, the hole would function as a register hole.) A wave travelling down the closed-hole part of the pipe can be partially reflected at the first open hole. And part of the wave can travel down to the first open hole in the series of open holes, where it is reflected. This gives rise to two standing waves, with different wavelength, and therefore different
