The IBM 2006 Speech Transcription System

TC-STAR is an European Union funded speech to speech translation project to transcribe, translate and synthesize European Parliamentary Plenary Speeches (EPPS). This paper describes IBM’s English and Spanish speech recognition systems submitted to the TC-STAR 2006 Evaluation. The technical advances in this submission include two different algorithms for automatic segmentation and speaker clustering of the input audio; a system architecture that is based on cross-adaptation across these two segmentation schemes and system combination through generation of an ensemble of systems using randomized decision tree state-tying; automatic punctuation of the speech recognition output; and the incorporation of an additional 35 hours of in-domain EPPS acoustic training data. These advances reduced the error rate by 30% relative over the best-performing system in the TC-STAR 2005 Evaluation on the 2006 English development test set, and produced one of the best performing systems on the 2006 evaluation in English with a word error rate of 8.3%.