Patent ID: 9241214
Filing Date: 2016-01-19
CPC Classification: G10L,H04R,H04S

Claim Text:
1. A direct sound extraction device, comprising: a Fourier transform unit which performs a Fourier transform process on an input signal that includes a reverberant sound in a direct sound; a spectrum transform unit which transforms, on the basis of frequency spectra of real and imaginary numbers of the input signal on which a Fourier transform process has been performed by the Fourier transform unit, the input signal to a first amplitude spectrum signal and a phase spectrum signal; a low-pass filter unit which carries out a low-pass filtering process on the first amplitude spectrum signal by using a preset normalized cutoff frequency for each frequency; a first limiter unit which limits a negative side of an amplitude of a second amplitude spectrum signal on which a low-pass filtering process has been performed by the low-pass filter unit, so as to bring the amplitude to zero; a first subtraction unit which calculates a third amplitude spectrum signal by subtracting the second amplitude spectrum signal whose negative-side amplitude has been limited by the first limiter unit from the first amplitude spectrum signal; a second limiter unit which limits a negative side of an amplitude of the third amplitude spectrum signal calculated by the first subtraction unit, so as to bring the amplitude to zero; an inverse spectrum transform unit which calculates, on the basis of the phase spectrum signal and the third amplitude spectrum signal whose negative-side amplitude has been limited by the second limiter unit, a signal that is made from frequency spectra of real and imaginary numbers; and an inverse Fourier transform unit which performs an inverse Fourier transform process on the signal calculated by the inverse spectrum transform unit to generate a direct sound signal that is obtained by extracting the direct sound from the input signal.