CONDITIONED CONSTANT-Q SPECTRA FOR IMPROVED FREQUENCY TRACKING THE PRESENCE OF INTERFERING SIGNALS

A technique is presented for improving the performance of a method for estimating the time-varying fundamental frequency of a signal corrupt ed by interference components. The original method involves the calcul ation and comparison of frequency-pair ratios in each short-time spect rum of the corrupted signal [M. Piszczalski and B. A. Galler, ''Predic ting musical pitch from component frequency ratios,'' J. Acoust. Sec. Am. 66, 710-720 (1979)]. As the strength of the interference component s is increased, the frequency estimates from this method become more u nreliable. To obtain improved performance, a procedure based upon prin cipal components analysis is used to enhance the harmonic signal's spe ctral components prior to the calculation of frequency-pair ratios. Th e resulting improvement in fundamental frequency estimation is demonst rated through examples involving music signals.