Recognition of classroom lectures in european portuguese

Abstract

Classroom lectures may be very challenging for automatic speech recognizers, because the vocabulary may be very specific and the speaking style very spontaneous. Our first experiments using a recognizer trained for Broadcast News resulted in word error rates near 60%, clearly confirming the need for adaptation to the specific topic of the lectures, on one hand, and for better strategies for handling spontaneous speech. This paper describes our efforts in these two directions: the different domain adaptation steps that lowered the error rate to 45%, with very little transcribed adaptation material, and the exploratory study of spontaneous speech phenomena in European Portuguese, namely concerning filled pauses.