Abstract: A noise canceller removes a noise component from an input speech signal. The noise canceller includes a noise cancellation coefficient adjuster that adjusts a noise cancellation coefficient to determine an amount of noise cancellation. A noise spectrum storage device stores an estimated noise spectrum. A noise estimator estimates a noise spectrum by comparing an input spectrum with a noise spectrum stored in the noise spectrum storage device. A noise canceling/spectrum compensator subtracts the noise spectrum stored in the noise spectrum storage device from the input spectrum based on a coefficient acquired by the noise cancellation coefficient adjuster.

Abstract: A code excited linear prediction speech decoder includes an adaptive codebook configured to generate an adaptive code vector. The decoder also includes a random codebook configured to generate a random code vector. The decoder also includes a a synthesis filter that receives a signal based on said adaptive code vector and said random code vector, and that is configured to perform linear prediction coefficient synthesis on said signal. The random codebook includes a pulse vector providing system configured to provide a pulse vector having a signed unit pulse. The random codebook also includes a comparing system configured to compare a value of adaptive codebook gain with a preset threshold value. The random codebook further includes a selecting system configured to select a dispersion pattern from a plurality of dispersion patterns stored in a memory in accordance with a result of said comparison.

Abstract: CELP-based speech encoder that performs encoding by decomposing one frame into a plurality of subframes, includes an LPC synthesizer that obtains synthesized speech by filtering an adaptive excitation vector and a stochastic excitation vector stored in an adaptive codebook and in an stochastic codebook using LPC coefficients obtained from input speech. A gain calculator calculates gains of the adaptive excitation vector and the stochastic excitation vector. A parameter coder performs vector quantization of the adaptive excitation vector and the stochastic excitation vector obtained by comparing distortions between the input speech and the synthesized speech. A pitch analyzer performs pitch analyses of a plurality of subframes in the frame respectively, before performing an adaptive codebook search for the first subframe, calculating correlation values and finding a value most approximate to the pitch period using the correlation values.

Abstract: A speech encoder includes an LPC synthesizer that obtains synthesized speech by filtering an adaptive excitation vector and a stochastic excitation vector stored in an adaptive codebook and in a stochastic codebook using LPC coefficients obtained from input speech. A gain calculator calculates gains of the adaptive excitation vector and the stochastic excitation vector and searches code of the adaptive excitation vector and code of the stochastic excitation vector by comparing distortions between the input speech and the synthesized speech obtained using the adaptive excitation vector and the stochastic excitation vector. A parameter coder performs predictive coding of gains using the adaptive excitation vector and the stochastic excitation vector corresponding to the codes obtained. The parameter coder comprises a prediction coefficient adjuster that adjusts at least one prediction coefficient used for the predictive coding according to at least one state of at least one previous subframe.

Abstract: A random code vector reading section and a random codebook of a conventional CELP type speech coder/decoder are respectively replaced with an oscillator for outputting different vector streams in accordance with values of input seeds, and a seed storage section for storing a plurality of seeds. This makes it unnecessary to store fixed vectors as they are in a fixed codebook (ROM), thereby considerably reducing the memory capacity.

Abstract: A random code vector reading section and a random codebook of a conventional CELP type speech coder/decoder are respectively replaced with an oscillator for outputting different vector streams in accordance with values of input seeds, and a seed storage section for storing a plurality of seeds . This makes it unnecessary to store fixed vectors as they are in a fixed codebook (ROM), thereby considerably reducing the memory capacity.

Abstract: A random code vector reading section and a random codebook of a conventional CELP type speech coder/decoder are respectively replaced with an oscillator for outputting different vector streams in accordance with values of input seeds, and a seed storage section for storing a plurality of seeds. This makes it unnecessary to store fixed vectors as they are in a fixed codebook (ROM), thereby considerably reducing the memory capacity.

Abstract: An excitation vector generator is provided for generating an excitation vector. The excitation vector includes a pulse vector generator that has at least one channel for generating pulse vectors. A memory stores at least one type of dispersion pattern for each of the channels. A dispersion pattern is selectively extracted from the memory for each of the channels. A dispersed vector generator generates a dispersed vector for every channel by convolution calculation using the extracted dispersion pattern and the generated pulse vectors. An excitation vector generator generates an excitation vector from the dispersed vectors generated by the dispersion vector generator.

Abstract: A random code vector reading section and a random codebook of a conventional CELP type speech coder/decoder are respectively replaced with an oscillator for outputting different vector streams in accordance with values of input seeds, and a seed storage section for storing a plurality of seeds. This makes it unnecessary to store fixed vectors as they are in a fixed codebook (ROM), thereby considerably reducing the memory capacity.

Abstract: First determiner 121 provisionally determines whether a current processing unit is a stationary noise region based on a determination result on stationary characteristics of a decoded signal. Based on the provisional determination result and a determination result on periodicity of the decoded signal, second determiner 124 further determines whether the current processing unit is a stationary noise region, whereby a decoded signal including a stationary speech signal such as a stationary vowel is distinguished from a stationary noise, and thus the stationary noise region is detected accurately.

Abstract: An Adaptive Sound Source Vector Generator (ASSVG) 103 sets preceding and succeeding pitch cycles centered on an integral-accuracy pitch cycle T0 selected in the previous subframe as a range for searching for a fractional-accuracy pitch frequency, and extracts an adaptive sound source vector P(T-frac) that has fractional-accuracy pitch cycle T-frac within this range from an Adaptive Code Book (ACB) 102. A Last Sub Frame Integral Pitch Cycle Storage (LSFIPCS) 108 stores integral component T0 of the optimal pitch cycle selected by a Distortion Comparator (DC) 107, and when a pitch cycle of the next subframe is searched for, outputs this optimal pitch cycle integral component T0 to the Adaptive Sound Source Vector Generator (ASSVG) 103. An Optimal Pitch Cycle Accuracy Judge Section (OPCAJS) 109 judges whether the optimal pitch cycle is of integral accuracy or fractional accuracy.

Abstract: In coding and decoding an acoustic parameter, a weighted vector is generated by multiplying a code vector output in a past frame and a code vector selected in a present frame by weighting factors respectively selected from a factor code book and adding the products to each other.

Abstract: The present invention carries out pre-selection on many LPC codevectors stored in an LSF codebook 101 using a weighted Euclidean distortion as a measure and carries out a full-code selection on the LPC codevectors left after the pre-selection using an amount of distortion in a spectral space as a measure. This makes it possible to improve the quantization performance of the LPC parameter vector quantizer and improve the quality of synthesized speech of the speech coder/decoder.

Abstract: A dispersed vector generator used in an excitation vector generator for a speech coder/decoder is provided. The dispersed vector generator includes a pulse vector generating section that generates a pulse vector having a signed unit pulse on one element of a vector axis. The dispersed vector generator also includes a dispersion pattern storing section that stores a plurality of dispersion patterns, a switch that selects a dispersion pattern out of the plurality of dispersion patterns stored in the dispersion pattern storing section and a pulse vector dispersion section that generates a dispersed vector by convoluting the selected dispersion pattern and the pulse vector.

Abstract: A random code vector reading section and a random codebook of a conventional CELP type speech coder/decoder are respectively replaced with an oscillator for outputting different vector streams in accordance with values of input seeds, and a seed storage section for storing a plurality of seeds. This makes it unnecessary to store fixed vectors as they are in a fixed codebook (ROM), thereby considerably reducing the memory capacity.

Abstract: A random code vector reading section and a random codebook of a conventional CELP type speech coder/decoder are respectively replaced with an oscillator for outputting different vector streams in accordance with values of input seeds, and a seed storage section for storing a plurality of seeds. This makes it unnecessary to store fixed vectors as they are in a fixed codebook (ROM), thereby considerably reducing the memory capacity.

Abstract: A random code vector reading section and a random codebook of a conventional CELP type speech coder/decoder are respectively replaced with an oscillator for outputting different vector streams in accordance with values of input seeds, and a seed storage section for storing a pluralitty of seeds This makes it unnecessary to store fixed vectors as they are in a fixed codebook (ROM) thereby considerably reducing the memory capacity.

Abstract: An excitation vector generator comprises a pulse vector generating section having N channels (N≧1) for generating pulse vectors, a storing section for storing M (M≧1)kinds of dispersion patterns every channel in accordance with N channels, a selecting section for selectively taking out a dispersion pattern from the storing section every channel, a dispersion section for performing a superimposing calculation of the extracted dispersion pattern and the generated pulse vectors every channel so as to generate N dispersion vectors, excitation vector generating section for generating an excitation vector from N dispersion vectors generated.

Abstract: A random code vector reading section and a random codebook of a conventional CELP type speech coder/decoder are respectively replaced with an oscillator for outputting different vector streams in accordance with values of input seeds, and a seed storage section for storing a plurality of seeds. This makes it unnecessary to store fixed vectors as they are in a fixed codebook (ROM), thereby considerably reducing the memory capacity.

Abstract: A random code vector reading section and a random codebook of a conventional CELP type speech coder/decoder are respectively replaced with an oscillator for outputting different vector streams in accordance with values of input seeds, and a seed storage section for storing a plurality of seeds . This makes it unnecessary to store fixed vectors as they are in a fixed codebook (ROM), thereby considerably reducing the memory capacity.