At a smoothing spectrogram calculation portion, a triangular interpolation function having a frequency width twice that of the fundamental frequency of a signal is obtained based on information on the fundamental frequency of the signal. The interpolation function and a spectrum obtained at an adaptive...http://www.google.com.hk/patents/US6115684?utm_source=gb-gplus-share專利 US6115684 - Method of transforming periodic signal using smoothed spectrogram, method of transforming sound using phasing component and method of analyzing signal using optimum interpolation function
