METHOD OF TRANSFORMING PERIODIC SIGNAL USING SMOOTHED SPECTROGRAM, METHOD OF TRANSFORMING SOUND USING PHASING COMPONENT AND METHOD OF ANALYZING SIGNAL USING OPTIMUM INTERPOLATION FUNCTION

摘要

At a smoothing spectrogram calculation portion, atriangular interpolation function having a frequency widthtwice that of the fundamental frequency of a signal isobtained based on information on the fundamental frequencyof the signal. The interpolation function and a spectrumobtained at an adaptive frequency analysis portion areconvoluted in the direction of frequency. Then, using atriangular interpolation function having a time lengthtwice that of a fundamental period, the spectruminterpolated in the frequency direction described above isfurther interpolated in the temporal direction, in orderto produce a smoothed spectrogram having the space betweengrid points on the time-frequency plane filled with thesurface of a bilinear function. Using the smoothedspectrogram, a speech sound is transformed. Therefore, theinfluence of periodicity in the frequency direction andthe temporal direction can be reduced.