N-gram Boosting: Improving Contextual Biasing with Normalized N-gram Targets

08/04/2023

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by   Wang Yau Li, et al.

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Accurate transcription of proper names and technical terms is particularly important in speech-to-text applications for business conversations. These words, which are essential to understanding the conversation, are often rare and therefore likely to be under-represented in text and audio training data, creating a significant challenge in this domain. We present a two-step keyword boosting mechanism that successfully works on normalized unigrams and n-grams rather than just single tokens, which eliminates missing hits issues with boosting raw targets. In addition, we show how adjusting the boosting weight logic avoids over-boosting multi-token keywords. This improves our keyword recognition rate by 26 LibriSpeech. This method is particularly useful on targets that involve non-alphabetic characters or have non-standard pronunciations.