Patent ID: 7359857

Claim:
A method of correcting spectral deformations in a voice, introduced by a communication network, comprising an equalization operation on a frequency band, adapted to an actual distortion of a transmission chain, said operation being performed by a digital filter having a frequency response which is a function of a ratio between a reference spectrum and a spectrum corresponding to a long-term spectrum of voice signals of speakers, comprising: communicating a constitution of classes of speakers with one voice reference per class prior to the equalization of a voice signal of a speaker; communicating a classification of the speaker, such that the speaker is allocated to the class from predefined classification criteria which causes a voice reference which is closest to the voice of the speaker to correspond to the speaker; performing equalization of a digitized signal of the voice of the speaker with, as a reference spectrum, the voice reference of the class to which the speaker has been allocated; wherein communicating the constitution of classes of speakers comprises selecting a corpus of N speakers recorded under non-deteriorated conditions, determining a long-term frequency spectrum of the selected corpus of N speakers, classifying the speakers of the corpus according to their partial cepstrum, and calculating the reference spectrum associated with each class to obtain the voice reference corresponding to each of the classes; wherein said ceptrum is calculated from the long-term spectrum restricted to the equalization band and by applying a predefined classification criterion to these cepstra to obtain K classes.