Code-Mixed Text Augmentation for Latvian ASR

Martins Kronis, Askars Salimbajevs, Mārcis Pinnis


Abstract
Code-mixing has become mainstream in the modern, globalised world and affects low-resource languages, such as Latvian, in particular. Solutions to developing an automatic speech recognition system (ASR) for code-mixed speech often rely on specially created audio-text corpora, which are expensive and time-consuming to create. In this work, we attempt to tackle code-mixed Latvian-English speech recognition by improving the language model (LM) of a hybrid ASR system. We make a distinction between inflected transliterations and phonetic transcriptions as two different foreign word types. We propose an inflected transliteration model and a phonetic transcription model for the automatic generation of said word types. We then leverage a large human-translated English-Latvian parallel text corpus to generate synthetic code-mixed Latvian sentences by substituting in generated foreign words. Using the newly created augmented corpora, we train a new LM and combine it with our existing Latvian acoustic model (AM). For evaluation, we create a specialised foreign word test set on which our methods yield up to 15% relative CER improvement. We then further validate these results in a human evaluation campaign.
Anthology ID:
2024.lrec-main.308
Volume:
Proceedings of the 2024 Joint International Conference on Computational Linguistics, Language Resources and Evaluation (LREC-COLING 2024)
Month:
May
Year:
2024
Address:
Torino, Italia
Editors:
Nicoletta Calzolari, Min-Yen Kan, Veronique Hoste, Alessandro Lenci, Sakriani Sakti, Nianwen Xue
Venues:
LREC | COLING
SIG:
Publisher:
ELRA and ICCL
Note:
Pages:
3469–3479
Language:
URL:
https://aclanthology.org/2024.lrec-main.308
DOI:
Bibkey:
Cite (ACL):
Martins Kronis, Askars Salimbajevs, and Mārcis Pinnis. 2024. Code-Mixed Text Augmentation for Latvian ASR. In Proceedings of the 2024 Joint International Conference on Computational Linguistics, Language Resources and Evaluation (LREC-COLING 2024), pages 3469–3479, Torino, Italia. ELRA and ICCL.
Cite (Informal):
Code-Mixed Text Augmentation for Latvian ASR (Kronis et al., LREC-COLING 2024)
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PDF:
https://aclanthology.org/2024.lrec-main.308.pdf