INTEGRATION OF PHONOTACTIC FEATURES FOR LANGUAGE IDENTIFICATION ON CODE-SWITCHED SPEECH

In this paper, phoneme sequences are used as language information to perform code-switched language
identification (LID). With the one-pass recognition system, the spoken sounds are converted into
phonetically arranged sequences of sounds. The acoustic models are robust enough to handle multiple
languages when emulating multiple hidden Markov models (HMMs). To determine the phoneme similarity
among our target languages, we reported two methods of phoneme mapping. Statistical phoneme-based
bigram language models (LM) are integrated into speech decoding to eliminate possible phone
mismatches. The supervised support vector machine (SVM) is used to learn to recognize the phonetic
information of mixed-language speech based on recognized phone sequences. As the back-end decision is
taken by an SVM, the likelihood scores of segments with monolingual phone occurrence are used to
classify language identity. The speech corpus was tested on Sepedi and English languages that are often
mixed. Our system is evaluated by measuring both the ASR performance and the LID performance
separately. The systems have obtained a promising ASR accuracy with data-driven phone merging
approach modelled using 16 Gaussian mixtures per state. In code-switched speech and monolingual
speech segments respectively, the proposed systems achieved an acceptable ASR and LID accuracy.