End-to-end speech recognition with Alignment RNN-Transducer

The Recurrent Neural Network Transducer (RNN-T) extends Connectionist Temporal Classification (CTC) by jointly modeling both input-output and output-output dependencies, and it has been successfully applied in end-to-end speech recognition. RNN-T adds language information by expanding its dimensions in this way, but the model training is difficult. And some paths of the model are unreasonable when decoding. Therefore, we present the Alignment RNN Transducer (ART) algorithm, which uses the forward-backward algorithm in CTC to find the best path alignment information as context-related information for training. We not only reduce the training dimensions but also adds context information to the model. And we still use CTC as the loss function to avoid decoding the impossible path in the RNN-T. We verify the algorithm on a Mandarin speech corpus AIShell-1, and it achieves a 13.65% CER, compared with the 16.79% CER given by the RNN-T model.