Speaker Adaptation for End-to-End CTC Models
Table 7: WERs (%) for supervised KLD regularization adaptation for the mix-unit CTC model on the 7-speaker set.
['Adapt. type', '# of utt.', '[ITALIC] α=0', '[ITALIC] α=0.2', '[ITALIC] α=0.5', '[ITALIC] α=0.8']
3.4.1 KLD Adaptation We first evaluate the KLD adaptation for the mix-unit CTC model on the 7-speaker dataset. Similar to the word CTC model, we observe consistent WER improvements with increasing number of adaptation utterances per speaker as expected. The best WER (15.48%) is obtained from adapting all hidden layers with α=0.0 on 200 utterances per speaker, providing a relative WERR 7.63% over the baseline SI mix-unit CTC model. We also observe the diminishing benefit of larger regularization for larger dataset (200 utterances) for adapting hidden layers.