Adapting Pretrained Models to Endangered Languages in Japan: A Comparative Study on Ryukyuan and Ainu Speech Recognition

Kohei Matsuura, Takanori Ashihara, Tatsuya Kawahara


Abstract
We investigate high-accuracy and speaker-robust automatic speech recognition (ASR) models by leveraging pretrained models for endangered languages in Japan — Ryukyuan (Shuri dialect) and Ainu (Saru dialect) — to support language and cultural preservation. In particular, this study presents the first experimental study on building and evaluating an ASR model for the Ryukyuan language. Specifically, we compare existing multilingual pretrained models, Whisper and XLS-R, with our in-house Japanese-focused model (JP-90k) pretrained solely on a large-scale weakly-supervised Japanese dataset. These models were fine-tuned on up to 10 and 32 hours of Ryukyuan and Ainu data, respectively. As a result, JP-90k consistently outperformed other models of the similar size in both languages. In addition, it demonstrated a remarkable advantage when training data was very limited, i.e., an hour or less. These findings suggest that large-scale pretraining on a language closely related to the target ones can yield robust low-resource ASR, including for unseen speakers and out-of-domain conditions. Furthermore, we found that all pretrained models achieved convergence in ASR accuracy with as little as 3-5 hours of fine-tuning data for both languages.
Anthology ID:
2026.lrec-1.112
Volume:
Proceedings of the Fifteenth Language Resources and Evaluation Conference
Month:
May
Year:
2026
Address:
Palma de Mallorca, Spain
Editors:
Stelios Piperidis, Núria Bel, Henk van den Heuvel, Nancy Ide, Simon Krek, Antonio Toral
Venue:
LREC
SIG:
Publisher:
ELRA Language Resource Association
Note:
Pages:
1455–1463
Language:
External URL:
https://lrec.elra.info/lrec2026-main-112
DOI:
10.63317/3iw5dymnwwbr
Bibkey:
Cite (ACL):
Kohei Matsuura, Takanori Ashihara, and Tatsuya Kawahara. 2026. Adapting Pretrained Models to Endangered Languages in Japan: A Comparative Study on Ryukyuan and Ainu Speech Recognition. In Proceedings of the Fifteenth Language Resources and Evaluation Conference, pages 1455–1463, Palma de Mallorca, Spain. ELRA Language Resource Association.
Cite (Informal):
Adapting Pretrained Models to Endangered Languages in Japan: A Comparative Study on Ryukyuan and Ainu Speech Recognition (Matsuura et al., LREC 2026)
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