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.