Pipe, usually wooden, used in orchestrions, photoplayers, and organs. The harmonic flute is open at the top and has a small hole at the nodal point (of the sound wave) about at the center of the front or back of the pipe. This hole causes the pipe to speak an octave higher than it normally would, more promptly and with greater tonal stability. A harmonic flute pipe is not quite as loud as the equivalent piccolo pipe that is half as long. Used in many types of instruments; certain Seeburg coin pianos and orchestrions have harmonic flutes, for example.