Automatic correction of i/y spelling in czech asr output

Abstract

This paper concentrates on the design and evaluation of the method that would be able to automatically correct the spelling of i/y in the Czech words at the output of the ASR decoder. After analysis of both the Czech grammar rules and the data, we have decided to deal only with the endings consisting of consonants b/f/l/m/p/s/v/z followed by i/y in both short and long forms. The correction is framed as the classification task where the word could belong to the “i” class, the “y” class or the “empty” class. Using the state-of-the-art Bidirectional Encoder Representations from Transformers (BERT) architecture, we were able to substantially improve the correctness of the i/y spelling both on the simulated and the real ASR output. Since the misspelling of i/y in the Czech texts is seen by the majority of native Czech speakers as a blatant error, the corrected output greatly improves the perceived quality of the ASR system.