Abstract: An audio signal processing device includes: a short-time fast Fourier transform unit that generates a signal in a frequency domain obtained by performing a short-time fast Fourier transform on an input audio signal; a steady sound determining unit that determines whether a waveform of a peak portion included in a waveform of the signal in a frequency domain is a steady sound; a filter coefficient calculation unit that dynamically calculates a filter coefficient on the basis of a result of determination made by the steady sound determining unit; a comb filter that operates according to the filter coefficient calculated by the filter coefficient calculation unit so as to filter a signal in a frequency domain; and an inverse Fourier transform unit that transforms an output of the comb filter into a signal in a time domain and outputs the signal in a time domain.

Abstract: An audio signal processing device includes: a short-time fast Fourier transform unit 4 that generates a signal in a frequency domain obtained by performing a short-time fast Fourier transform on an input audio signal; a steady sound determining unit 5 that determines whether a waveform of a peak portion included in a waveform of the signal in a frequency domain is a steady sound; a filter coefficient calculation unit 6 that dynamically calculates a filter coefficient on the basis of a result of determination made by the steady sound determining unit 5; a comb filter 7 that operates according to the filter coefficient calculated by the filter coefficient calculation unit 6 so as to filter a signal in a frequency domain; and an inverse Fourier transform unit 8 that transforms an output of the comb filter 7 into a signal in a time domain and outputs the signal in a time domain.

Abstract: An audio waveform processing not imparting any feeling of strangeness and high in definition, in which time stretch and pitch shift are performed by a vocoder method, and the variation of phase over the whole waveform caused by the vocoder method at all times is reduced. An audio input waveform is handled as one band as it is or subjected to frequency band division into bands. While performing time stretch and pitch shift of each band waveform like conventional vocoder methods, the waveforms are combined. The combined waveform of the band is phase-synchronized at regular intervals to reduce the variation of phase. The phase-synchronized waveforms of the band are added, thus obtaining the final output waveform.