Thomson-Csf

Thales

Philippe Gournay

Fr&eacute;d&eacute;ric Chartier

Gilles Quagliaro

Yves-Paul Nakache

Gwena&euml;l Guilmin

A speech encoding/decoding method using an encoder working at very low bit rates, comprises a learning step enabling the identification of the representatives of the speech signal; and an encoding step to segment the speech signal and determine the best representative associated with each recognized segment. The method also comprises at least one step for the encoding/decoding of at least one of the parameters of the prosody of the recognized segments, e.g., the energy, pitch, voicing, and/or length of the segments, by using a piece of information on prosody pertaining to the best representatives. The method can employ a bit rate of lower than 400 bits per second.

Method for the encoding of prosody for a speech encoder working at very low bit rates

A method for encoding speech at a low bit rate. The method assembles parameters on N consecutive frames to form a super-frame. A vector quantization of transition frequencies of a voicing during each super-frame is made. Only the most frequent configurations are transmitted without deterioration and the least frequent configurations are replaced by the configuration that is the nearest in terms of absolute error among most frequent configurations. The pitch is encoded in carrying out a scalar quantization of only one value of the pitch for each super-frame. The energy is encoded in selecting only a reduced number of values in assembling these values in sub-packets quantized by vector quantization. The spectral envelope parameters are encoded by vector quantization in selecting only a determined number of filters. The untransmitted energy values are recovered in the synthesis part by interpolation or extrapolation from transmitted values. Such a method may find particular application in vocoders.

Method for quantizing speech coder parameters

A method for providing auditory correction for a hearing-impaired individual, including extracting pitch, voicing, energy and spectrum characteristics of an input speech signal. The method also includes modifying the extracted pitch characteristic by multiplying a pitch factor times the extracted pitch characteristic, modifying the extracted voicing characteristic by multiplying a voicing factor times the extracted voicing characteristic, modifying the extracted energy characteristic by applying a compression function to the extracted energy characteristic, and modifying the extracted spectrum characteristic by applying a homothetical compression function to the extracted spectrum characteristic. Further, a speech signal is reconstituted perceptible to the hearing-impaired individual based on the modified pitch, voicing, energy and spectrum characteristics.

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Asnieres, France

Philippe Gournay