Abstract: Filters 106-1-106-N divide an input signal 100 into N band-limited signals 107-1-107-N, and multipliers 108-1-108-N carry out dynamic range control of the N band-limited signals 107-1-107-N, respectively. After that, filters 111-1-111-N eliminate odd harmonics caused by the dynamic range control, and a signal synthesis unit 113 combines the signals passing through the filters 111-1-111-N into a single output signal 114.

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 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 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 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 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: Filters 106-1-106-N divide an input signal 100 into N band-limited signals 107-1-107-N, and multipliers 108-1-108-N carry out dynamic range control of the N band-limited signals 107-1-107-N, respectively. After that, filters 111-1-111-N eliminate odd harmonics caused by the dynamic range control, and a signal synthesis unit 113 combines the signals passing through the filters 111-1-111-N into a single output signal 114.

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 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 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 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 sound encoder multiplexes a plurality of codes into a sound code in an order determined by a multiplexing order determination unit (12), and a sound decoder demultiplexes the sound code into a plurality of codes one by one in an order determined by a demultiplexing order determination unit (14).

Abstract: A sound encoder multiplexes a plurality of codes into a sound code in an order determined by a multiplexing order determination unit (12), and a sound decoder demultiplexes the sound code into a plurality of codes one by one in an order determined by a demultiplexing order determination unit (14).

Abstract: A sound encoder multiplexes a plurality of codes into a sound code in an order determined by a multiplexing order determination unit (12), and a sound decoder demultiplexes the sound code into a plurality of codes one by one in an order determined by a demultiplexing order determination unit (14).

Abstract: A speech encoding apparatus calculates encoding distortion of a noise-like fixed code vector and multiplies the encoding distortion by a fixed weight corresponding to the noise-like degree of the noise-like fixed code vector, calculates encoding distortion of a non-noise-like fixed code vector and multiplies the encoding distortion by a fixed weight corresponding to the non-noise-like fixed code vector, and selects the fixed excitation code associated with multiplication result with a smaller value.

Abstract: A speech coding apparatus comprises a repetition period pre-selecting unit for generating a plurality of candidates for the repetition period of a driving excitation source by multiplying the repetition period of an adaptive excitation source by a plurality of constant numbers, respectively, and for pre-selecting a predetermined number of candidates from all the candidates generated. A driving excitation source coding unit provides both excitation source location information and excitation source polarity information that minimize a coding distortion, for each of the predetermined number of candidates, and provides an evaluation value associated with the minimum coding distortion for each of the predetermined number of candidates.

Abstract: A speech coding apparatus comprises a repetition period pre-selecting unit for generating a plurality of candidates for the repetition period of a driving excitation source by multiplying the repetition period of an adaptive excitation source by a plurality of constant numbers, respectively, and for pre-selecting a predetermined number of candidates from all the candidates generated. A driving excitation source coding unit provides both excitation source location information and excitation source polarity information that minimize a coding distortion, for each of the predetermined number of candidates, and provides an evaluation value associated with the minimum coding distortion for each of the predetermined number of candidates.