High Performance Sequence-to-Sequence Model for Streaming Speech Recognition
Table 3: Latency and accuracy of the S2S models with unidirectional and chunk-based encoders using immortal prefix.
['[BOLD] Encoder', '[BOLD] Beam Size', 'Δ', '[BOLD] WER', '[BOLD] Latency']
The chunk-based encoder closes the gap and moves closer to the performance of the bidirectional encoder when a large chunk size is used. As the encoder’s states are fixed early, the inferences are already stable when Δ=30 for all beam sizes. To achieve 1-second delay, all the approaches need to trade-off for an accuracy reduction of 5% relatively. In term of latency, the chunk-based approach with K=80 and beamsize=2 and Δ=30 is the best setting in this setup.