Abstract: A method for the time scaling of a sampled audio signal is presented. The method includes a first step of performing a pitch and voicing analysis of each frame of the signal in order to determine if a given frame is voiced or unvoiced and to evaluate a pitch profile for voiced frames. The results of this analysis are used to determine the length and position of analysis windows along each frame. Once an analysis window is determined, it is overlap-added to previously synthesized windows of the output signal.

Abstract: An approach is provided for maintaining natural pitch periodicity of the speech or audio signal when processing a late frame in a predictive decoder. Concealment is performed to replace a late frame. The late frame that includes audio information is detected. A pitch phase difference introduced by the concealment is determined. The pitch phase difference is compensated for before playing out a subsequent frame that follows the late frame.

Abstract: Apparatus is provided that includes at least one entity for transmitting speech signals in a discontinuous transmission mode including transmitting speech frames interspersed with frames including comfort noise parameters during periods of speech pauses. The entit(ies) include a first entity for estimating a current noise value. In addition, the apparatus includes a second entity for selectively controlling a rate at which the frames including comfort noise parameters are transmitted during the periods of speech pauses based upon the estimated current noise value.

Abstract: 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.

Abstract: The present invention relates to a method and device for improving concealment of frame erasure caused by frames of an encoded sound signal erased during transmission from an encoder (106) to a decoder (110), and for accelerating recovery of the decoder after non erased frames of the encoded sound signal have been received. For that purpose, concealment/recovery parameters are determined in the encoder or decoder. When determined in the encoder (106), the concealment/recovery parameters are transmitted to the decoder (110). In the decoder, erasure frame concealment and decoder recovery is conducted in response to the concealment/recovery parameters. The concealment/recovery parameters may be selected from the group consisting of: a signal classification parameter, an energy information parameter and a phase information parameter.

Abstract: 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.

Abstract: 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.

Abstract: 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 comprises at least one step for the encoding/decoding of at least one of the parameters of the prosody of the recognized segments, such as the energy and/or pitch and/or voicing and/or length of the segments, by using a piece of information on prosody pertaining to the “best representatives”. Application to bit rates lower than 400 bits per second.