Title
LEARNING WORD-LEVEL CONFIDENCE FOR SUBWORD END-TO-END ASR
Abstract
We study the problem of word-level confidence estimation in subword-based end-to-end (E2E) models for automatic speech recognition (ASR). Although prior works have proposed training auxiliary confidence models for ASR systems, they do not extend naturally to systems that operate on word-pieces (WP) as their vocabulary. In particular, ground truth WP correctness labels are needed for training confidence models, but the non-unique tokenization from word to WP causes inaccurate labels to be generated. This paper proposes and studies two confidence models of increasing complexity to solve this problem. The final model uses self-attention to directly learn word-level confidence without needing subword tokenization, and exploits full context features from multiple hypotheses to improve confidence accuracy. Experiments on Voice Search and long-tail test sets show standard metrics (e.g., NCE, AUC, RMSE) improving substantially. The proposed confidence module also enables a model selection approach to combine an on-device E2E model with a hybrid model on the server to address the rare word recognition problem for the E2E model.
Year
DOI
Venue
2021
10.1109/ICASSP39728.2021.9413966
2021 IEEE INTERNATIONAL CONFERENCE ON ACOUSTICS, SPEECH AND SIGNAL PROCESSING (ICASSP 2021)
Keywords
DocType
Citations 
Automatic speech recognition, confidence, calibration, transformer, attention-based end-to-end models
Conference
0
PageRank 
References 
Authors
0.34
0
12
Name
Order
Citations
PageRank
David Qiu100.68
Li, Qiujia254.48
Yanzhang He36416.36
Yu Zhang444241.79
Bo Li520642.46
liangliang cao6181690.71
Rohit Prabhavalkar716322.56
Deepti Bhatia800.34
Wei Li9436140.67
Ke Hu1011.73
Tara N. Sainath113497232.43
Ian McGraw1225324.41