Unified Simplified Grapheme Acoustic Modeling for Medieval Latin LVCSR

摘要

A large vocabulary continuous speech recognition (LVCSR) system designed for dictation of medieval Latin language documents is introduced. Such language technology tool can be of great help for preserving Latin language charters from this era, as optical character recognition systems are often challenged by these historical materials. As corresponding historical research focuses on the Visegrad region, our primary aim is to make medieval Latin dictation available for texts and speakers of this region, concentrating on Czech, Hungarian and Polish. The baseline acoustic models we start with are monolingual grapheme-based ones. On one hand, the application of medieval Latin knowledge-based grapheme-to-phoneme (G2P) mapping from the source language to the target language resulted in significant improvement, reducing the Word Error Rate (WER) by 13.3%. On the other hand, applying a Unified Simplified Grapheme (USG) inventory set for the three-language acoustic data set complemented with Romanian speech data, resulted in a further 0.7% WER reduction - without using any target or source language G2P rules.