Multilevel and Session Variability Compensated Language Recognition: ATVS-UAM Systems at NIST LRE 2009

This paper presents the systems submitted by the ATVS Biometric Recognition Group to the 2009 Language Recognition Evaluation (LRE'09), organized by NIST. New challenges included in this LRE edition can be summarized by three main differences with respect to past evaluations. First, the number of languages to be recognized expanded to 23 languages from 14 in 2007, and 7 in 2005. Second, the data variability has been increased by including telephone speech excerpts extracted from Voice of America (VOA) radio broadcasts through Internet in addition to conversational telephone speech (CTS). The third difference was the volume of data, involving in this evaluation up to 2 terabytes of speech data for development, which is an order of magnitude greater than past evaluations. LRE'09 thus required participants to develop robust systems able not only to successfully face the session variability problem but also to do it with reasonable computational resources. ATVS participation consisted of state-of-the-art acoustic and high-level systems focussing on these issues. Furthermore, the problem of finding a proper combination and calibration of the information obtained at different levels of the speech signal was widely explored in this submission. In this paper, two original contributions were developed. The first contribution was applying a session variability compensation scheme based on factor analysis (FA) within the statistics domain into a SVM-supervector (SVM-SV) approach. The second contribution was the employment of a novel back-end based on anchor models in order to fuse individual systems prior to one-versus-all calibration via logistic regression. Results both in development and evaluation corpora show the robustness and excellent performance of the submitted systems, exemplified by our system ranked second in the 30-second open-set condition, with remarkably scarce computational resources.