Speaker verification using coded speech

The implementation of a pseudo text-independent Speaker Verification system is described. This system was designed to use only information extracted directly from the coded parameters embedded in the ITU-T G.729 bit-stream. Experiments were performed over the YOHO database [1]. The feature vector as a short-time representation of speech consists of 16 LPC-Cepstral coefficients, as well as residual information appended in the form of a pitch estimate and a measure of vocality of the speech. The robustness in verification accuracy is also studied. The results show that while speech coders, G.729 in particular, introduce coding distortions that lead to verification performance degradation, proper augmented use of unconventional information nevertheless leads to a competitive performance on par with that of a well-studied traditional system which does not involve signal coding and transmission. The result suggests that speaker verification over a cell phone connection remains feasible even though the signal has been encoded to 8 Kb/s.