Minimum bayesian risk methods for automatic speech recognition

摘要

A hypothesis space of a search graph may be determined. The hypothesis space may include n hypothesis-space transcriptions of an utterance, each selected from a search graph that includes t>n transcriptions of the utterance. An evidence space of the search graph may also be determined. The evidence space may include m evidence-space transcriptions of the utterance that are randomly selected from the search graph, where t>m. For each particular hypothesis-space transcription in the hypothesis space, an expected word error rate may be calculated by comparing the particular hypothesis-space transcription to each of the evidence-space transcriptions. Based on the expected word error rates, a lowest expected word error rate may be obtained, and the particular hypothesis-space transcription that is associated with the lowest expected word error rate may be provided.

主权项

1. A method comprising:
selecting, by a computing device, n hypothesis-space transcriptions of an utterance from a search graph that includes t>n transcriptions of the utterance, wherein selecting the n hypothesis-space transcriptions comprises determining n best transcriptions of the utterance according to a maximum a posteriori (MAP) technique; randomly selecting m evidence-space transcriptions of the utterance from the search graph, wherein t>m; for each particular hypothesis-space transcription of the n hypothesis-space transcriptions, calculating an expected word error rate by comparing the particular hypothesis-space transcription to the randomly selected m evidence-space transcriptions; based on the expected word error rates, determining a lowest expected word error rate; and providing the particular hypothesis-space transcription that is associated with the lowest expected word error rate.