TRANSCRIPTION OF BROADCAST TELEVISION AND RADIO NEWS: THE 1996 ABBOT SYSTEM

摘要

Abbot is a hybrid connectionist-HMM large vocabulary continuous speech recognition system developed at the Cambridge University Engineering Department. This uses a recurrent neural network acoustic model to map acoustic features into posterior phone probabilities. These posterior probabilities are then converted to scaled likelihoods and used as observation likelihoods for phone HMMs [1, 2]. This paper describes the development of the CU-CON system which participated in the 1996 ARPA Hub 4 Evaluations. The system is based on Abbot. The Hub 4 Evaluation task involves the transcription of broadcast television and radio news programmes. This is an extremely demanding task for state-of-the-art speech recognition systems. Typical programmes include a wide variety of speaking styles and acoustic conditions. These range from read speech recorded in the studio to extemporaneous speech recorded over telephone channels. Results are presented for the system at various stages of development, as well as for the final evaluation system.