Handling uncertain observations in unsupervised topic-mixture language model adaptation

Ekapol Chuangsuwanich, Shinji Watanabe, Takaaki Hori, Tomoharu Iwata, James R. Glass

Abstract: We propose an extension to the recent approaches in topic-mixture modeling such as Latent Dirichlet Allocation and Topic Tracking Model for the purpose of unsupervised adaptation in speech recognition. Instead of using the 1-best input given by the speech recognizer, the proposed model takes confusion network as an input to alleviate recognition errors. We incorporate a selection variable which helps reweight the recognition output, thus creating a more accurate latent topic estimate. Compared to adapting based on just one recognition hypothesis, the proposed model show WER improvements on two different tasks.