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5745648 Apparatus and method for analyzing speech signals to determine parameters expressive of characteristics of the speech signals  
An apparatus and method for locating a plurality of roots of a line spectrum pair expression on a unit circle. The method comprises the steps of: (1) receiving an initial value for locating a first...
5742927 Noise reduction apparatus using spectral subtraction or scaling and signal attenuation between formant regions  
A noise reduction apparatus and method for enhancing noisy speech signal which applies to the spectral component signals of a time-varying input signal either a spectral substraction process or a...
5742734 Encoding rate selection in a variable rate vocoder  
It is a first objective of the present invention to provide a method by which to reduce the probability of coding low energy unvoiced speech as background noise. The present invention determines an...
5742733 Parametric speech coding  
This invention is a new kind of parametric speech coding system in which the parametrization according to a speech production model is carried out not only on the speech signal to be coded but also...
5737484 Multistage low bit-rate CELP speech coder with switching code books depending on degree of pitch periodicity  
A voice coder system is capable of coding speech at low bit rates with high speech quality. Speech signals are divided into frames and further divided into subframes. A spectral parameter...
5734790 Low bit rate speech signal transmitting system using an analyzer and synthesizer with calculation reduction  
In a speech signal encoding system comprising a maximum similarity series extracting unit (50) for producing a series of excitation pulses appearing at an equidistant time interval and an identical...
5732188 Method for the modification of LPC coefficients of acoustic signals  
In a CELP coding scheme, p-order LPC coefficients of an input signal are transformed into n-order LPC cepctrum coefficients c j (S 2 ), which are modified into n-order modified LPC cepstrum...
5732389 Voiced/unvoiced classification of speech for excitation codebook selection in celp speech decoding during frame erasures  
A CELP speech decoder includes a first portion comprising an adaptive codebook and a second portion comprising a fixed codebook. The CS-ACELP decoder generates a speech excitation signal...
5729655 Method and apparatus for speech compression using multi-mode code excited linear predictive coding  
An apparatus and method of coding speech. The apparatus includes a first circuit being coupled to receive a first signal, the first signal corresponds to the speech signal. The first circuit is for...
5729654 Vector encoding method, in particular for voice signals  
The vector encoding method, particularly for voice signals, includes storing autocorrelation coefficients in one codebook and performing a logic operation on the autocorrelation coefficients with...
5724480 Speech coding apparatus, speech decoding apparatus, speech coding and decoding method and a phase amplitude characteristic extracting apparatus for carrying out the method  
A speech coding and decoding apparatus for improving the quality of synthesized speech. A coding portion includes a filter for adding a short-term phase amplitude characteristic to an excitation...
5719994 Determination of an excitation vector in CELP encoder  
The present invention relates to a method for determining an excitation vector in a CELP speech signal encoder, said vector belonging to a subset associated with a larger set of excitation vectors...
5719993 Long term predictor  
An improved long-term predictor (LTP) for use in analysis-by-synthesis coding systems, such as CELP is disclosed. The invention provides control of the periodicity of speech signals generated by...
5719992 Constrained-stochastic-excitation coding  
In CELP coding, stochastic (noise-like) excitation is used in exciting a cascade of long-term and short-term all-pole linear synthesis filters. This approach is based on the observation that the...
5717819 Methods and apparatus for encoding/decoding speech signals at low bit rates  
A voice encoder for use in low bit rate vocoding applications employs a method of encoding a plurality of digital information frames. This method includes the step of providing an estimate of the...
5717825 Algebraic code-excited linear prediction speech coding method  
The method uses the technique of CELP coding with algebraic codebook. The search for the CELP excitation includes a calculation of certain components of the covariance matrix U=H T H where H...
5717824 Adaptive speech coder having code excited linear predictor with multiple codebook searches  
Methods and apparatus determining codevectors in response to a speech signal include a first codebook member which stochastically determines the characteristics of a bi-pulse codevector...
5717822 Computational complexity reduction during frame erasure of packet loss  
A speech coding system robust to frame erasure (or packet loss) is described. Illustrative embodiments are directed to a modified version of CCITT standard G.728. In the event of frame erasure,...
5710863 Speech signal quantization using human auditory models in predictive coding systems  
A speech compression system called "Transform Predictive Coding", or TPC, provides for encoding 7 kHz wideband speech (160 kHz sampling) at a target bit-rate range of 16 to 32 kb/s (1 to 2...
5706394 Telecommunications speech signal improvement by reduction of residual noise  
A telecommunications network service overcomes the annoying effects of transmitted noise by signal processing which filters out the noise using a model-based iterative signal estimator. The...
5704001 Sensitivity weighted vector quantization of line spectral pair frequencies  
A novel and improved method and apparatus for quantizing the line spectral pair (LSP) frequencies in a speech compression system is disclosed. A novel and computationally efficient procedure for...
5704002 Process and device for minimizing an error in a speech signal using a residue signal and a synthesized excitation signal  
The present invention relates to a device and process for the digital coding and decoding of speech comprising a short term prediction, a long term prediction and a residual wave coding technique...
5704004 Apparatus and method for normalizing and categorizing linear prediction code vectors using Bayesian categorization technique  
The present invention discloses a pattern matching system applicable for syllable recognition which includes a dictionary means for storing a plurality of standard patterns each representing a...
5701392 Depth-first algebraic-codebook search for fast coding of speech  
A codebook is searched in view of encoding a sound signal. This codebook consists of a set of codevectors each of 40 positions and comprising N non-zero-amplitude pulses assignable to predetermined...
5699485 Pitch delay modification during frame erasures  
In a speech decoder which experiences frame erasure, the pitch delay associated with the first of consecutive erased frames is incremented. The incremented value is used as the pitch delay for the...
5699477 Mixed excitation linear prediction with fractional pitch  
An analyzer and synthesizer (500) for human speech using LPC filtering (530) of an excitation of mixed (508-518-520) voiced pulse train (502) and unvoiced noise (512) with fractional sampling...
5699483 Code excited linear prediction coder with a short-length codebook for modeling speech having local peak  
A predicted residual signal is calculated from a current input speech signal and a past input speech signal, and a cross-correlation between the predicted residual signal and the past input speech...
5699482 Fast sparse-algebraic-codebook search for efficient speech coding  
A method of encoding a speech signal is provided. This method improves the excitation codebook and search procedure of the conventional Code-Excited Linear Prediction (CELP) speech encoders. This...
5696874 Multipulse processing with freedom given to multipulse positions of a speech signal  
In a multipulse processing device for achieving a high encoding efficiency without using a high sampling frequency for an input signal and with a great degree of freedom given to positions of...
5696873 Vocoder system and method for performing pitch estimation using an adaptive correlation sample window  
An improved vocoder system and method for estimating pitch in a speed waveform. The method comprises an improved correlation method for estimating the pitch parameter which more accurately...
5694519 Tunable post-filter for tandem coders  
An adaptive postfilter is used on the decoding side of tandem codecs (coder/decoders). Post-filter parameters are adapted using a backward synthesis filter. The parameters used are 10th order LPC...
5692101 Speech coding method and apparatus using mean squared error modifier for selected speech coder parameters using VSELP techniques  
An improved speech coder provides a more natural sounding replication of speech by modifying the mean-squared error criterion for the selected speech coder parameters. Specifically, the...
5689615 Usage of voice activity detection for efficient coding of speech  
A method for efficient coding of non-active voice periods is disclosed for a speech communication system with (a) a speech encoder, (b) a communication channel and (c) a speech decoder. The method...
5687284 Excitation signal encoding method and device capable of encoding with high quality  
In an excitation signal encoding method comprising the steps of, dividing a speech signal into a plurality of frames, dividing each of the plurality of frames into a plurality of subframes each of...
5684920 Acoustic signal transform coding method and decoding method having a high efficiency envelope flattening method therein  
An input acoustic signal is subjected to modified discrete cosine transform processing to obtain its spectrum characteristics. Linear prediction coefficients are derived from the input acoustic...
5682462 Very low bit rate voice messaging system using variable rate backward search interpolation processing  
A method and apparatus is provided for a low bit rate speech transmission. Speech spectral parameter vectors are generated from a voice message and stored in a sequence of speech spectral parameter...
5673361 System and method for performing predictive scaling in computing LPC speech coding coefficients  
A system and method for calculating linear predictive coding (lpc) coefficients in response to a received speech signal waveform. The system of the present invention uses a method referred to as...
5671327 Speech encoding apparatus utilizing stored code data  
A learning-type speech encoding apparatus comprises an adaptive code book storing driving signal vectors, a minimum distortion searching circuit for searching the adaptive code book for an optimum...
5668924 Digital sound recording and reproduction device using a coding technique to compress data for reduction of memory requirements  
A sound recording and reproducing device codes a sound signal by a code excited linear predictive coding means including an adaptive code book created on the basis of past excitation signals, a...
5664055 CS-ACELP speech compression system with adaptive pitch prediction filter gain based on a measure of periodicity  
A speech coding system employing an adaptive codebook model of periodicity is augmented with a pitch-predictive filter (PPF). This PPF has a delay equal to the integer component of the pitch-period...
5664053 Predictive split-matrix quantization of spectral parameters for efficient coding of speech  
The present invention concerns efficient quantization of more than one LPC spectral models per frame in order to enhance the accuracy of the time-varying spectrum representation without...
5664054 Spike code-excited linear prediction  
A conventional CELP speech codec synthesizes a pitch interval in a sound by synthesizing a scaled innovation signal--typically, a random signal--and adding it to a scaled pitch signal derived from...
5659659 Speech compressor using trellis encoding and linear prediction  
A speech compressor utilizing Trellis Encoding and Linear Prediction (TELP). A TELP speech compressor provides improved signal generation and search technique for a code-excited linear prediction...
5657421 Speech signal transmitter wherein coding is maintained during speech pauses despite substantial shut down of the transmitter  
In so-called Code Excited Linear Prediction (CELP) coding methods for speech signal transmission, a codebook look-up method is used which is very processor-intensive. To conserve power, during...
5657350 Audio coder/decoder with recursive determination of prediction coefficients based on reflection coefficients derived from correlation coefficients  
A coder/decoder for samples of speech or other audio signals with bit rate reduction includes an adaptive prediction filter having filter coefficients which are recursively computed according to...
5651091 Method and apparatus for low-delay CELP speech coding and decoding  
A low-bitrate (typically 8 kbit/s or less), low-delay digital coder and decoder based on Code Excited Linear Prediction for speech and similar signals features backward adaptive adjustment for...
5649056 Speech recognition system and method which permits a speaker's utterance to be recognized using a hidden markov model with subsequent calculation reduction  
A sound analyzer sound analyzes an input speech signal to obtain feature vectors. A matrix quantizer performs a matrix quantization process between the feature vectors obtained by the sound...
5646991 Noise replacement system and method in an echo canceller  
A noise replacement system and method for providing a synthesized noise replacement signal to an output speech channel in an echo cancellation system. A far-end speech signal transmitted through a...
5642464 Methods and apparatus for noise conditioning in digital speech compression systems using linear predictive coding  
In methods and apparatus for processing a speech signals comprising a plurality of successive signal intervals, each signal interval containing no speech sounds is classified as a noise interval,...
5642465 Linear prediction speech coding method using spectral energy for quantization mode selection  
A speech signal digitized as successive frames is subjected to analysis-by-synthesis in order to obtain, for each frame, quantization values of synthesis parameters allowing reconstruction of an...
Matches 551 - 600 out of 749 < 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 >