Abstract: A correction spectrum calculation unit 6 obtains a correction spectrum by smoothing an estimated noise spectrum in accordance with the degree of its variations, and a suppression quantity limiting coefficient calculation unit 7 decides a suppression quantity limiting coefficient from the correction spectrum. A suppression quantity calculation unit 9 obtains a suppression coefficient based on the suppression quantity limiting coefficient, and the spectrum suppression unit 10 carries out amplitude suppression of spectral components of an input signal.

Abstract: A noise suppression device includes: a power spectrum calculator converting an input signal of time domain into power spectra of frequency domain; a voice/noise determination unit determining whether the power spectra indicate voice or noise; a noise spectrum estimation unit estimating noise spectra of the power spectra; a period component estimation unit analyzing a harmonic structure constituting the power spectra and estimating periodical information about the power spectra; a weighting coefficient calculator calculating a weighting coefficient for weighting the power spectra; a suppression coefficient calculator calculating a suppression coefficient for suppressing noise included in the power spectra; a spectrum suppression unit suppressing amplitude of the power spectra in accordance with the suppression coefficient; and an inverse Fourier transformer converting the power spectra output by the spectrum suppression unit into a signal of time domain to generate a noise-suppressed signal.

Abstract: A noise reduction device comprises a SN ratio obtaining unit configured to obtain a SN ratio as a function of an estimated noise spectrum and an arithmetic product of an averaged power spectrum of the input signal and noise likeliness signal, and an output signal obtaining unit configured to obtain a output signal whose noise is reduced based on the input signal and the SN ratio obtained by the SN ratio obtaining unit.

Abstract: A band separating unit 5 carries out a band division of a plurality of power spectra into which an input signal is converted by a time-to-frequency converting unit 2 to combine power spectra into each subband, and a band representative component generating unit 6 defines a power spectrum having a maximum among the plurality of power spectra within each subband as a representative power spectrum. A noise suppression amount generating unit 7 calculates an amount of noise suppression for each subband by using the representative power spectrum and a noise spectrum, and a noise suppressing unit 9 suppresses the amplitudes of the power spectra according to the amount of noise suppression.

Abstract: A synthesis filter 106 synthesizes a plurality of wide-band speech signals by combining wide-band phoneme signals and sound source signals from a speech signal code book 105, and a distortion evaluation unit 107 selects one of the wide-band speech signals with a minimum waveform distortion with respect to an up-sampled narrow-band speech signal output from a sampling conversion unit 101. A first bandpass filter 103 extracts a frequency component outside a narrow-band of the wide-band speech signal and a band synthesis unit 104 combines it with the up-sampled narrow-band speech signal.

Abstract: A voice/noise section decision unit 2 makes a decision from a low-frequency amplitude spectrum 102 as to whether an input signal 100 is like a voice or not. A noise spectrum estimation unit 3 estimates a low-frequency noise spectrum and high-frequency noise spectrum from the output of the voice/noise section decision unit 2. A low-frequency processing unit 201 and a high-frequency processing unit 202 perform noise suppression based on the noise spectrum output from the noise spectrum estimation unit 3.

Abstract: A noise suppressor selects, for individual frequency components, maximums by comparing a plurality of noise suppressed spectra 105 and 106 a plurality of noise suppressing units 4 and 5 output, thereby obtaining an output spectrum 107 having the frequency components selected as its components. A first noise suppressing unit 4 generates a noise suppressed spectrum 105 by multiplying an input spectrum 102 by amplitude suppression gains, and makes the amplitude suppression gains greater than most of the amplitude suppression gains in a noise signal intervals of a second noise suppressing unit 5.

Abstract: A processed component calculating unit 14 obtains a transformed noise suppressed spectrum 18a based on the ratio between a noise suppressed spectrum 18 and an estimated noise spectrum 17, and a phase disturbing unit 15 performs phase disturbance to obtain a processed spectrum 19 consisting of smoothed components that make deterioration components in the noise suppressed spectrum 18 subjectively imperceptible. A signal addition unit 11 adds the processed spectrum 19 to the frequency components of the noise suppressed spectrum 18 deteriorated through the noise suppression of a noise suppressing unit 3 to suppress the deterioration components.

Abstract: A noise reduction device including: an input signal spectrum obtaining unit that obtains an input signal spectrum by a subband unit based on a current frame of an input signal; an averaged spectrum obtaining unit that obtains an averaged spectrum of the input signal by averaging the input signal spectrum; an estimated noise spectrum obtaining unit that obtains an estimated noise spectrum estimated based on a past frame of the input signal by the subband unit; and an SN ratio obtaining unit that obtains an SN ratio by the subband unit, based on the averaged spectrum of the input signal obtained by the averaged spectrum obtaining unit, the estimated noise spectrum obtained by the estimated noise spectrum obtaining unit, and a function of the averaged spectrum of the input signal obtained by the averaged spectrum obtaining unit and the estimated noise spectrum obtained by the estimated noise spectrum obtaining unit.

Abstract: A noise suppression device comprises subband SN ratio calculation means which receives a noise likeness signal, an input signal spectrum and a subband-based estimated noise spectrum, calculates the subband-based input signal average spectrum, calculates a subband-based mixture ratio of the subband-based estimated noise spectrum to the subband-based input signal average spectrum on the basis of the noise likeness signal, and calculates the subband-based SN ratio on the basis of the subband-based estimated noise spectrum, the subband-based input signal average spectrum and the mixture ratio.

Abstract: A noise suppression device calculates a subband SN ratio calculation based on a noise likeness signal, an input signal spectrum and a subband-based estimated noise spectrum. The device calculates a subband-based input signal average spectrum, calculates a subband-based mixture ratio of the subband-based estimated noise spectrum to the subband-based input signal average spectrum on the basis of the noise likeness signal, and calculates the subband-based SN ratio on the basis of the subband-based estimated noise spectrum, the subband-based input signal average spectrum and the mixture ratio.

Abstract: A noise suppression device comprises subband SN ratio calculation means which receives a noise likeness signal, an input signal spectrum and a subband-based estimated noise spectrum, calculates the subband-based input signal average spectrum, calculates a subband-based mixture ratio of the subband-based estimated noise spectrum to the subband-based input signal average spectrum on the basis of the noise likeness signal, and calculates the subband-based SN ratio on the basis of the subband-based estimated noise spectrum, the subband-based input signal average spectrum and the mixture ratio.

Abstract: A noise suppression device comprises subband SN ratio calculation means which receives a noise likeness signal, an input signal spectrum and a subband-based estimated noise spectrum, calculates the subband-based input signal average spectrum, calculates a subband-based mixture ratio of the subband-based estimated noise spectrum to the subband-based input signal average spectrum on the basis of the noise likeness signal, and calculates the subband-based SN ratio on the basis of the subband-based estimated noise spectrum, the subband-based input signal average spectrum and the mixture ratio.

Abstract: A noise suppression device comprises subband SN ratio calculation means which receives a noise likeness signal, an input signal spectrum and a subband-based estimated noise spectrum, calculates the subband-based input signal average spectrum, calculates a subband-based mixture ratio of the subband-based estimated noise spectrum to the subband-based input signal average spectrum on the basis of the noise likeness signal, and calculates the subband-based SN ratio on the basis of the subband-based estimated noise spectrum, the subband-based input signal average spectrum and the mixture ratio.

Abstract: A noise suppression device comprises subband SN ratio calculation means which receives a noise likeness signal, an input signal spectrum and a subband-based estimated noise spectrum, calculates the subband-based input signal average spectrum, calculates a subband-based mixture ratio of the subband-based estimated noise spectrum to the subband-based input signal average spectrum on the basis of the noise likeness signal, and calculates the subband-based SN ratio on the basis of the subband-based estimated noise spectrum, the subband-based input signal average spectrum and the mixture ratio.

Abstract: An amplitude suppression quantity denoting a noise suppression level of a current frame is calculated in an amplitude suppression quantity calculating unit (20), a perceptual weight distributing pattern of both a spectral subtraction quantity and a spectral amplitude suppression quantity is determined in a perceptual weight pattern adjusting unit (21), the spectral subtraction quantity and the spectral amplitude suppression quantity given by the perceptual weight distributing pattern are corrected according to a frequency band SN ratio in a perceptual weight correcting unit (7), a noise subtracted spectrum is calculated from an amplitude spectrum, a noise spectrum and a corrected spectral subtraction quantity in a spectrum subtracting unit (8), and a noise suppressed spectrum is calculated from the noise subtracted spectrum and a corrected spectral amplitude suppression quantity in a spectrum suppressing unit (9).

Abstract: In the noise suppression apparatus, a spectrum correction gain calculation unit calculates the noise amplitude spectrum correction gain and the noise removal spectrum correction gain using the input amplitude spectrum, noise amplitude spectrum and respective coefficients; a spectrum deduction unit deducts the product of the noise amplitude spectrum and the noise amplitude spectrum correction gain from the input amplitude spectrum and outputs the result as a first noise removal spectrum; a spectrum suppression unit multiplies the first noise removal spectrum by the noise removal spectrum correction gain and outputs the result as a second noise removal spectrum; finally a frequency/time conversion unit converts the second noise removal spectrum into a time domain signal.

Abstract: An echo processor includes an echo suppression amount decider which compares a state of an outgoing input signal to be sent including an echo with a state of an incoming input signal and calculates an echo suppression amount based on the comparison, a time-frequency transformer which transforms the outgoing input signal in the time domain into the frequency domain, thereby generating an amplitude spectrum and a phase spectrum, a noise-spectrum estimator which estimates a noise spectrum from the amplitude spectrum, a mixer which mixes an amount of the noise spectrum based on the echo suppression amount with the amplitude spectrum, and a frequency-time transformer which generates an outgoing output signal including a noise in the time domain on the basis of the amplitude spectrum, with which an amount of the noise spectrum is mixed by the mixer, and the phase spectrum, and outputs the outgoing output signal.

Abstract: A noise suppressor device for attaining perceptually preferable noise suppression is disclosed. The device minimizes reduction in quality even in the presence of increased noises. The device is adaptable for use in voice communications systems and speech recognition systems employed in a variety of kinds of noisy environments. The device includes a spectrum subtracter and a spectrum amplitude suppressor that operate on the basis of perceptual weights.

Abstract: A noise suppression device comprises subband SN ratio calculation means which receives a noise likeness signal, an input signal spectrum and a subband-based estimated noise spectrum, calculates the subband-based input signal average spectrum, calculates a subband-based mixture ratio of the subband-based estimated noise spectrum to the subband-based input signal average spectrum on the basis of the noise likeness signal, and calculates the subband-based SN ratio on the basis of the subband-based estimated noise spectrum, the subband-based input signal average spectrum and the mixture ratio.