Sound Radiation from the Mouth of an Organ Pipe

A double‐ended organ pipe, symmetrical about its midplane, was blown at one of its mouthpieces and radiation patterns were observed in an anechoic chamber. The sharp nulls on the midplane show that the unexcited end is very nearly as strong a source as the blown end. Thus, the blowing jet current, even though chopped by the switching action, does not contribute materially to the radiated sound. This also implies that the jet current does not contribute directly to sustaining oscillations in the pipe.