ASA 127th Meeting M.I.T. 1994 June 6-10

3aMU7. Measurement of harmonic ratios of sounds produced by musical instruments.

Judith C. Brown

Media Lab., MIT, Cambridge, MA 02139

Wellesley College, Wellesley, MA 02181

A recently developed high resolution pitch tracker [J. C. Brown and M. S. Puckette, J. Acoust. Soc. Am. 94, 662--667 (1993)] has made it possible to measure the ratios of the frequencies of the upper harmonics of a sound with respect to its fundamental frequency with high accuracy. Calculations were carried out on digitized sounds produced by a cello, viola, alto flute, clarinet, and piano. The sounds produced by the stringed instruments included examples both with and without vibrato. Measured ratios were exactly equal to integers for all instruments except the piano with an upper bound of error of 3 cents. As expected the piano was found to have stretched harmonics with the measured inharmonicity increasing for harmonics 2 through 5. The major limitation on this method of calculation was found to be extraneous noise, and this was greatest for the stringed instruments.