Further experiments in text-independent speaker recognition over communications channels

Experiments are described in automatic, text-independent speaker recognition using three databases: good quality read speech, conversations over simulated telephone links, and conversations over real telephone links. A recognition system is evaluated on this material using a set of features which were believed to have some resistance to transmission degradations, namely, F0statistics and statistics of low-order cepstrum coefficient variation. Performance is reasonable on the first two databases but poor on the telephone speech. A new set of features based on the frequencies of peaks in the short-term smoothed spectrum is found to perform better on the telephone speech, presumably because of its greater resistance to noise and nonlinear distortions. A computer simulation of the recognition experiments is described. The results of the simulation indicate that performance estimates from recognition experiments should be allowed wide error tolerances, and they illustrate the danger of trying too many features on the same database.