Recently, end-to-end speech recognition with a hybrid model consisting of the connectionist temporal classification(CTC) and the attention encoder-decoder achieved state-of-the-art results. In this paper, we propose a novel CTC decoder structure based on the experiments we conducted and explore the relation between decoding performance and the depth of encoder. We also apply attention smoothing mechanism to acquire more context information for subword-based decoding. Taken together, these strategies allow us to achieve a word error rate(WER) of 4.43% without LM and 3.34% with RNN-LM on the test-clean subset of the LibriSpeech corpora, which by far are the best reported WERs for end-to-end ASR systems on this dataset.
@article{arxiv.1810.12020,
title = {An improved hybrid CTC-Attention model for speech recognition},
author = {Zhe Yuan and Zhuoran Lyu and Jiwei Li and Xi Zhou},
journal= {arXiv preprint arXiv:1810.12020},
year = {2018}
}
Comments
Submitted to the 2019 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Brighton, UK, May 2019