Abstract: A method includes masking the voice of a speaker by intentionally altering the pitch and the timbre of their voice. An audio signal corresponding to an original recording of the voice of the speaker is divided (11) into a series of successive audio segments of a determined constant duration. A rising frequency alteration (12a) is applied to a timbre (A) extracted from each audio segment. A falling frequency alteration (12b) is applied to a pitch (B) extracted from each audio segment. The altered pitch and the altered timbre of the audio segment are combined (14) so as to form a single resulting altered audio segment. From one audio segment to another in the series of audio segments, a variation (13a) of the rising alteration and a variation (13b) of the falling alteration are applied. These variations fluctuate randomly from one audio segment to another in the series of audio segments.

Abstract: A process and apparatus for measuring the resemblance between sound samples incorporating a learning phase and a test phase, each having a digital acquisition and preprocessing stage, an order p acoustic analysis stage and a p.times.p covariance matrix calculating stage with respect to the resulting vector signal, the learning phase also having a reference X covariance matrix inversion stage and a stage of storing the thus obtained matrix X.sup.-1 in a dictionary, the test phase incorporating a stage of multiplying the covariance matrix of test Y with the reference matrix X.sup.-1, a stage of extracting all or part of the p eigenvalues .lambda.k of said matrix product and a calculating stage using a family of functions f, called generalized sphericity functions, so as to obtain a digital value measuring the resemblance between the considered test sample and the reference samples of the dictionary.