Abstract: A noise suppressing apparatus suppresses a noise component of a sound signal which contains the noise component and a signal component. In the apparatus, a frequency analyzing section divides the sound signal into a plurality of frames such that adjacent frames overlap with each other along a time axis, and computes a first spectrum of each frame. A noise suppressing section suppresses a noise component of the first spectrum so as to provide a second spectrum of each frame in which the noise component is suppressed. A frequency specifying section specifies a frequency of a noise component of each frame. A phase controlling section varies a phase of the noise component corresponding to the specified frequency in the second spectrum by a different variation amount each frame.

Abstract: In a noise suppression apparatus, an index setter sets an exponent K that is a positive value. A factor setter variably sets a suppression factor according to the exponent K. A noise suppressor generates an audio signal from which a noise component is suppressed through noise suppression process of suppressing a Kth power of an amplitude of the noise component at each frequency thereof in a Kth power of an amplitude of the audio signal at each frequency thereof to a degree determined according to the suppression factor set by the factor setting part. Preferably, the index setter sets the exponent K to a value less than 0.1.

Abstract: A noise suppressing device is provided for suppressing noise of a first audio signal to generate a second audio signal. In the noise suppressing device, a noise acquisition unit acquires a plurality of noise components which are different from each other. A noise suppression unit generates each suppression component by suppressing each noise component from the first audio signal, thereby providing a plurality of suppression components different from each other in correspondence to the plurality of the noise components. A signal generation unit generates the second audio signal by summing the plurality of the suppression components that are provided from the noise suppression unit.

Abstract: In an audio processing device, a target sound emphasizer generates a target sound emphasized component by emphasizing a target sound component contained in a plurality of audio signals generated by a plurality of sound receiving devices. A stereo processor generates a stereo component of a plurality of channels from the plurality of audio signals. A first adjuster adjusts a sound pressure level of the target sound emphasized component according to a first adjustment value, and a second adjuster adjusts a sound pressure level of the stereo component according to a second adjustment value. A variable setter variably sets a zoom value which is changeable between a wide angle side and a telephoto side relative to a target.

Abstract: A In a noise suppression apparatus, an extractor extracts a noise component from an audio signal. A stationary noise estimator estimates stationary noise included in the noise component. A first noise suppressor removes a spectrum of the stationary noise from a spectrum of the audio signal to an extent determined by a subtraction factor. A non-stationary noise estimator estimates a spectrum of non-stationary noise by subtracting the spectrum of the stationary noise from the spectrum of the noise component. A factor setter generates a filtering factor for emphasizing a target sound component contained in the audio signal from the spectrum of the non-stationary noise. A second noise suppressor performs a filtering process using the filtering factor on the audio signal after processing of the first noise suppressor.

Abstract: A signal processing device processes a plurality of observed signals at a plurality of frequencies. The plurality of the observed signals are produced by a plurality of sound receiving devices which receive a mixture of a plurality of sounds. In the signal processing device, a storage stores observed data of the plurality of the observed signals. The observed data represents a time series of magnitude of each frequency in each of the plurality of the observed signals. An index calculator calculates an index value from the observed data for each of the plurality of the frequencies. The index value indicates significance of learning of a separation matrix using the observed data of each frequency. The separation matrix is used for separation of the plurality of the sounds from each other at each frequency. A frequency selector selects one or more frequency according to the index value of each frequency.

Abstract: A noise suppression estimation device calculates a noise index value which varies according to kurtosis of a frequence distribution of magnitude of a sound signal before or after suppression of the noise component, the noise index value indicating a degree of occurrence of musical noise after suppression of the noise component in a frequency domain. For example, the noise suppression estimation device calculates first kurtosis of a frequence distribution of magnitude of the sound signal before suppression of the noise component, calculates second kurtosis of a frequence distribution of magnitude of the sound signal after suppression of the noise component, and calculates the noise index value from the first kurtosis and the second kurtosis.

Abstract: A noise suppressing apparatus suppresses a noise component of a sound signal which contains the noise component and a signal component. In the apparatus, a frequency analyzing section divides the sound signal into a plurality of frames such that adjacent frames overlap with each other along a time axis, and computes a first spectrum of each frame. A noise suppressing section suppresses a noise component of the first spectrum so as to provide a second spectrum of each frame in which the noise component is suppressed. A frequency specifying section specifies a frequency of a noise component of each frame. A phase controlling section varies a phase of the noise component corresponding to the specified frequency in the second spectrum by a different variation amount each frame.

Abstract: A time-axis compression/expansion method and apparatus for multitrack signals is provided, which is capable of performing time-axis compression/expansion on a multitrack signal in such an appropriate manner as to prevent a degradation in the sound quality of a sound generated through a multichannel reproduction or a sound generated through reproduction of a musical tone signal obtained by mix-down. Positions of attacks of the rhythm track sound source signal of a plurality of track sound source signals are detected. Portions of the rhythm track sound source signal between the detected positions of attacks are subjected to a first time-axis compression/expansion process, and the other track sound source signals are subjected to a second time-axis compression/expansion process, based on the detected positions of attacks.

Abstract: A time-axis compression/expansion system compresses or expands a multichannel signal at a specified compression/expansion rate. Waveform segments are sequentially cut out from each channel signal. A cutting starting point of a leading end portion of a waveform segment following each preceding waveform segment of the cut out waveform segments is determined commonly between the channel signals, based on two portions of a waveform of a synthesized signal formed by synthesizing the channel signals within a range of predetermined search parameters of the waveform of the synthesized signal. The two portions correspond to a time period over which cross-fading is to be carried out and are most similar to each other. The preceding waveform segment and the following waveform segment cut from each channel signal are spliced together by cross-fading a trailing end portion of the preceding waveform segment and the leading end portion of the following waveform segment.

Abstract: A vector quantizer and a vector quantization method are provided, which do not allow the embedding position of the watermark information to be identified easily, and thus enable unfair use of the vector quantized information to be accurately found out. Waveform extraction is performed on input signal data to output extracted waveform data. Index data are generated based on the output extracted waveform data. As index data to be generated based on predetermined extracted waveform data in which no watermark information is to be embedded, out of the output extracted waveform data, index data is randomly selected, which corresponds to the predetermined extracted waveform data from a plurality of index data which, when decoded, have amounts of errors falling within a predetermined range with respect to the predetermined extracted waveform data before decoding.

Abstract: A time-scale modification method or apparatus is basically designed to effect a time-scale modification process (i.e., expansion or compression with respect to time) on rhythm source signals containing waves such that rhythm sounds are not substantially changed in pitches. Herein, attack positions are detected from the rhythm source signals by using thresholds which are determined in advance. Hence, the time-scale modification process is performed on intermediate signal portions of the rhythm source signals between the attacks in accordance with a desired time-scale modification factor. Then, the intermediate signal portions subjected to the time-scale modification process are smoothly connected with other signal portions such as the attacks and their proximal portions, which are not subjected to the time-scale modification process.

Abstract: A speech encoding and decoding system comprises a speech coding apparatus and a speech decoding apparatus. The speech encoding apparatus orthogonally transforms an input speech signal represented in a time domain into a signal represented in a frequency domain in units of predetermined blocks, smoothes the resulting orthogonal transform coefficients by auxiliary information obtained by analyzing the speech signal, vector-quantizes the smoothed orthogonal transform coefficients to generate a quantization index, extracts a vector quantization error of low frequency components of the vector-quantized smoothed orthogonal transform coefficients, scalar-quantizes the vector quantization error to determine low frequency range correction information, and outputs the auxiliary information, quantization index, and low frequency range correction information.

Abstract: A pitch/tempo converting apparatus is constructed for concurrently changing a tempo and a pitch of an audio signal according to tempo designation information and pitch designation information. In the apparatus, a memory section memorizes the audio signal composed of original amplitude values sequentially sampled at original sampling points timed by an original sampling rate within an original frame period. A tempo converting section converts the original frame period into an actual frame period by varying a length of the original frame period according to the tempo designation information so as to change the tempo of the audio signal. A pitch converting section converts each of the original sampling points into each of actual sampling points by shifting each of the original sampling points according to the pitch designation information so as to change the pitch of the audio signal.

Abstract: An encoding apparatus provided at the transmission side includes a low pass filter, a high pass filter, a nonvoice band detecter, a switch and an adder for separating a speech component and a background noise component from an inputted signal. The low pass filter provides a voice band of the speech component and the high pass filter provides a nonvoice band of the speech component. The nonvoice band component is separated from the background noise portion of the output of the high pass filter and re-combined with the voice band to provide the separated speech component. The separated speech component and the background component are individually encoded by a speech encoder and a noise encoder, respectively, and transmitted. In a decoding apparatus at the reception side, the speech component and the background noise component are individually decoded by a speech decoder and a noise decoder, respectively.