Segregation of Speakers for Speaker Adaptation in TV News Audio

Speaker adaptation is commonly used to compensate speaker variation in large vocabulary continuous speech recognition. In a multi-speaker environment where speakers change frequently speaker segregation is needed to divide the input audio stream to speaker turns. Speaker turns define the current speaker at each time and speaker adaptation can thus be done based on speaker turns. The novelty of this paper is that the speaker-specific transformations are estimated incrementally and in tandem with speaker segregation. Therefore we need a transformation that can be reliably estimated based on one speaker turn alone. We propose the constrained maximum likelihood linear regression (CMLLR) for this. In testing with Finnish TV news audio, speaker adaptation reduced the average letter error rate 25% relative to baseline.