Abstract
The orchestral woodwind instruments have been empirically designed to give musical tones heard with a single definite pitch and a characteristic quality. However, certain unorthodox fingerings and/or embouchure adjustments can result in tones of a quite different character. They are heard as perhaps two separate pitches sounding simultaneously, or as perhaps a tone of rather indefinite pitch but of a ’’rough’’ or ’’beating’’ quality. Such tones have been named multiphonics. They were investigated as follows: The instrument was fingered and blown to produce a multiphonic tone. A microphone, supplied with an appropriate probe, picked up the internal standing wave; the microphone output was recorded on tape. Loops made from this tape allowed the internal standing wave to be reproduced continously for analysis. The input impedance curve of the instrument with the multiphonic fingering was also plotted. It was found that multiphonic tones consist of two independently generated main components, one associated with the lowest resonance of the instrument, and the other with the third and fourth resonance. Furthermore, the higher-frequency component is amplitude modulated somewhat by the low-frequency component because of the nonlinearity of the air flow through the reed aperture. This results in two more components whose frequencies are given by the difference and sum, respectively, of the two main component frequencies. Interactions of harmonics of the main components may generate other smaller higher-frequency components. Listening tests demonstrated that the ear generally can hear the two main components and the difference frequency; in some cases other components can also be heard.
Published Version
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