method of extracting the fundamental frequency or the fundamental period of the periodic waveform noise is added

摘要

PROBLEM TO BE SOLVED: To provide a method for extracting a fundamental period or a fundamental frequency of a periodical waveform with added noise, that is noise-resistant and moreover permits to extract the precise fundamental period or the fundamental frequency. SOLUTION: Target sound with suppressed noise is obtained by observing mixed sound x(t) in which target sound of a harmonic structure and noise are mixed at a sole sound receiving source, roughly estimating a fundamental frequency of the target sound s(t) from the observed mixed sound x(t) by using a fundamental frequency estimation method through a comb line filter resistant to the noise n(t), extracting estimated noise through a band-width variable comb line filter made to match with the estimated fundamental frequency, suppressing the estimated noise by subtracting the estimated noise from the original mixed sound, estimating a highly accurate fundamental frequency by using a fundamental frequency estimation method on the basis of an instantaneous frequency to the signal suppressed in the noise, and estimating and removing the noise through the band-width variable comb line filter using this highly accurate fundamental frequency.