Google Inc.

David Qiu

Yanzhang He

Yu Zhang

Liangliang Cao

Ian Mcgraw

Qiujia Li

Tara N Sainath

Wei Ping Li

Bo Li

Rohit Prakash Prabhavalkar

Khe Chai Sim

Wei Li

Ke Hu

Deepti Bhatia

Tsendsuren Munkhdalai

A method including receiving a speech recognition result corresponding to a transcription of an utterance spoken by a user. For each sub-word unit in a sequence of hypothesized sub-word units of the speech recognition result, using a confidence estimation module to: obtain a respective confidence embedding associated with the corresponding output step when the corresponding sub-word unit was output from the first speech recognizer; generate a confidence feature vector; generate an acoustic context vector; and generate a respective confidence output score for the corresponding sub-word unit based on the confidence feature vector and the acoustic feature vector received as input by the output layer of the confidence estimation module. The method also includes determining, based on the respective confidence output score generated for each sub-word unit in the sequence of hypothesized sub-word units, an utterance-level confidence score for the transcription of the utterance.

Multi-task learning for end-to-end automated speech recognition confidence and deletion estimation

An automatic speech recognition (ASR) system that includes an ASR model, a neural associative memory (NAM) biasing model, and a confidence estimation model (CEM). The ASR model includes an audio encoder configured to encode a sequence of audio frames characterizing a spoken utterance into a sequence of higher-order feature representations, and a decoder configured to receive the sequence of higher-order feature representations and output a final speech recognition result. The NAM biasing model is configured to receive biasing contextual information and modify the sequence of higher-order feature representations based on the biasing contextual information to generate, as output, biasing context vectors. The CEM is configured to compute a confidence of the final speech recognition result output by the decoder. The CEM is connected to the biasing context vectors generated by the NAM biasing model.

Context-aware neural confidence estimation for rare word speech recognition

A method includes receiving a speech recognition result, and using a confidence estimation module (CEM), for each sub-word unit in a sequence of hypothesized sub-word units for the speech recognition result: obtaining a respective confidence embedding that represents a set of confidence features; generating, using a first attention mechanism, a confidence feature vector; generating, using a second attention mechanism, an acoustic context vector; and generating, as output from an output layer of the CEM, a respective confidence output score for each corresponding sub-word unit based on the confidence feature vector and the acoustic feature vector received as input by the output layer of the CEM. For each of the one or more words formed by the sequence of hypothesized sub-word units, the method also includes determining a respective word-level confidence score for the word. The method also includes determining an utterance-level confidence score by aggregating the word-level confidence scores.

Learning word-level confidence for subword end-to-end automatic speech recognition

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David Qiu