Toward Robust Speech Recognition and Understanding
Journal of VLSI Signal Processing Systems
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In order to improve the performance of speech recognition systems when speakers change frequently and each of them utters a series of several sentences, a new unsupervised, online and incremental speaker adaptation technique combined with automatic detection of speaker changes is proposed. The speaker change is detected by comparing likelihoods using speaker-independent and speaker-adaptive Gaussian mixture models (GMMs). Both the phone HMM and GMM are adapted by MLLR transformation. In a broadcast news transcription task, this method reduces the word error rate by 10.0%. In comparison with the conventional method that uses HMMs for the speaker change detection, the GMM-based method requires a significantly less number of computations at the cost of only a slightly lower word recognition rate.