Papers › CAT: A CTC-CRF based ASR Toolkit Bridging the Hybrid and the End-to-end Approaches...
CAT: A CTC-CRF based ASR Toolkit Bridging the Hybrid and the End-to-end Approaches towards Data Efficiency and Low Latency
Keyu An, Hongyu Xiang, Zhijian Ou
In this paper, we present a new open source toolkit for speech recognition, named CAT (CTC-CRF based ASR Toolkit). CAT inherits the data-efficiency of the hybrid approach and the simplicity of the E2E approach, providing a full-fledged implementation of CTC-CRFs and complete training and testing scripts for a number of English and Chinese benchmarks. Experiments show CAT obtains state-of-the-art results, which are comparable to the fine-tuned hybrid models in Kaldi but with a much simpler training pipeline. Compared to existing non-modularized E2E models, CAT performs better on limited-scale datasets, demonstrating its data efficiency. Furthermore, we propose a new method called contextualized soft forgetting, which enables CAT to do streaming ASR without accuracy degradation. We hope CAT, especially the CTC-CRF based framework and software, will be of broad interest to the community, and can be further explored and improved.
Code
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Tasks
Results from the paper archive 2025-07-28
| Task | Dataset | Model | Metric | Value | Rank at snapshot | Leaderboard | Report |
|---|---|---|---|---|---|---|---|
| Speech Recognition | AISHELL-1 | CTC-CRF 4gram-LM | Word Error Rate (WER) | 6.34 | #15 of 18 | Archive leaderboard | report |
| Speech Recognition | Hub5'00 FISHER-SWBD | CTC-CRF | Word Error Rate (WER) | 12 | #1 of 1 | Archive leaderboard | report |
| Speech Recognition | Hub5'00 SwitchBoard | CTC-CRF | CallHome | 18.4 | #4 of 5 | Archive leaderboard | report |
| Speech Recognition | Hub5'00 SwitchBoard | CTC-CRF | Hub5'00 | 14.1 | #4 of 5 | Archive leaderboard | report |
| Speech Recognition | Hub5'00 SwitchBoard | CTC-CRF | SwitchBoard | 9.7 | #4 of 5 | Archive leaderboard | report |
| Speech Recognition | WSJ dev93 | CTC-CRF VGG-BLSTM | Word Error Rate (WER) | 5.7 | #2 of 4 | Archive leaderboard | report |
| Speech Recognition | WSJ eval92 | CTC-CRF VGG-BLSTM | Word Error Rate (WER) | 3.2 | #9 of 17 | Archive leaderboard | report |
Ranks are positions in the archive's leaderboards as they stood at the 2025-07-28 snapshot. Results published since then are not among these rows, so a rank here is not a current standing.
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