Double Gauss Based Unsupervised Score Normalization in Speaker Verification

In text-independent speaker verification, unsupervised mode can improve system performance. In traditional systems, the speaker model is updated when a test speech has a score higher than a particular threshold; we call this unsupervised model training. In this paper, an unsupervised score normalization is proposed. A target speaker score Gauss and an impostor score Gauss are set up as a prior; the parameters of the impostor score model are updated using the test score. Then the test score is normalized by the new impostor score model. When the unsupervised score normalization, unsupervised model training and factor analysis are adopted in the NIST 2006 SRE core test, the EER of the system is 4.29%.