The ISL evaluation system for Verbmobil-II

Describes the 2000 ISL large vocabulary speech recognition system for fast decoding of conversational speech which was used in the German Verbmobil-II project. The challenge of this task is to build robust acoustic models to handle different dialects, spontaneous effects, and crosstalk as occur in conversational speech. We present speaker incremental normalization and adaptation experiments close to real-time constraints. To reduce the number of consequential errors caused by out-of-vocabulary words, we conducted filler-model experiments to handle unknown proper names. The overall improvements from 1998 to 2000 resulted in a word error reduction from 40% to 17% on our development test set.