Judith C. Brown
Media Lab., MIT, Cambridge, MA 02139
Wellesley College, Wellesley, MA 02181
Miller S. Puckette
IRCAM, Paris 75004, France
When the Fourier components of a sound with harmonic frequency components are plotted against log frequency, a constant pattern independent of fundamental frequency is obtained. A computationally efficient implementation [J. C. Brown and M. S. Puckette, ``An efficient algorithm for the calculation of a constant Q transform,'' J. Acoust. Soc. Am. (to be published 1992)] will be described. One can then calculate the cross-correlation function of these spectra with the ideal pattern, which consists of ones at the positions of the harmonic frequency components, to obtain the fundamental frequency of the input signal. Extremely accurate values of the fundamental frequency can be obtained using a method based on phase changes of the discrete Fourier transform [J. C. Brown and M. S. Puckette, ``A high resolution fundamental frequency determination based on phase changes of the Fourier transform,'' submitted to J. Acoust. Soc. Am. (1992)]. Results for a variety of musical instruments will be presented, including recent results on tracking very low frequencies produced by a cello.