Developments in Large Vocabulary Dictation : The LIMSI Nov94 NAB System

In this paper we report on our development work in large vocabulary , American English continuous speech dictation on the ARPA NAB task in preparation for the November 1994 evaluation. We have experimented with (1) alternative analyses for the acoustic front end, (2) the use of an enlarged vocabulary of 65k words so as to reduce the number of errors due to out-of-vocabulary words, (3) extensions to the lexical representation, (4) the use of additional acoustic training data, and (5) modiication of the acoustic models for telephone speech. The recognizer was evaluated on Hubs 1 and 2 of the fall 1994 ARPA NAB CSR Hub and Spoke Benchmark test. Experimental results on development and evaluation test data are given, as well as an analysis of the errors on the development data.