Loquendo - Politecnico di Torino's 2008 NIST speaker recognition evaluation system

This paper describes the improvements introduced in the Loquendo-Politecnico di Torino (LPT) speaker recognition system submitted to the NIST SRE08 evaluation campaign. This system, which was among the best participants in this evaluation, combines the results of three core acoustic systems, two based on Gaussian mixture models (GMMs), and one on phonetic GMMs. We discuss the results of the experiments performed for the 10sec-10sec condition and for the core condition, including the challenging tasks involving a target speaker and an interviewer. The error rate reduction of our SRE08 system compared to the SRE06 system ranges from 25% of the telephone-interview condition to 57% of the interview-interview condition. On the test with telephone and microphone conversations, the improvements range from 9% to 32%.