Spoken Language Identification Using Lstm-Based Angular Proximity

This paper describes the design of an acoustic language identification (LID) system based on LSTMs that directly maps a sequence of acoustic features to a vector in a vector space where the angular proximity corresponds to a measure of language/dialect similarity. A specific architecture for the LSTM-based language vector extractor is introduced along with the angular proximity loss function to train it. This new LSTM-based LID system is quicker to train than a standard RNN topology using stacked layers trained with the cross-entropy loss function and obtains significantly lower language error rates. Experiments compare this approach to our previous developments on the subject. as well as to two widely used LID techniques: a phonotactic system using DNN acoustic models and an i-vector system. Results are reported on two different data sets: the 14 languages of NIST LRE07 and the 20 closely related languages and dialects of NIST LRE15. In addition to reporting the NIST Cavg metric which served as the primary metric for the LRE07 and LRE15 evaluations, the average LER is provided.