Unsupervised speaker adaptation of DNN-HMM by selecting similar speakers for lecture transcription

Unsupervised speaker adaptation of Deep Neural Network (DNN) is investigated for lecture transcription tasks, in which a single speaker gives a long speech and thus speaker adaptation is important. The proposed method selects similar speakers to the test data (test speaker) from the training database, which are used for retraining the baseline DNN. Several speaker characteristic features are defined for the speaker similarity measure. The feature based on Universal Background Model (UBM) and principal component analysis (PCA) achieves the best performance, resulting in a significant improvement from the baseline DNN and also from the adapted GMM-HMM system. The method is combined with a naive adaptation method using the initial ASR hypothesis of the test data, and an additional improvement is achieved.