AdiDhwani: Preservation-Oriented ASR for Endangered Bhili and Mundari Languages

Pooja Singh, M Kaab Bin Shahid, Sandeep Kumar


Abstract
India’s tribal (*Janjatiya/Adivasi*) languages remain absent from public ASR evaluation, despite their importance for oral history, ecological knowledge, and cultural continuity. We present **AdiDhwani**, a preservation-oriented ASR benchmark for **Bhili** (ISO 639-3: ‘bhb‘), India’s largest non-scheduled language, and **Mundari** (ISO 639-3: ‘unr‘), a Vulnerable North Munda language. The benchmark comprises 56.5 hours of community-validated Bhili speech and 11.7 hours of Mundari speech with fixed evaluation splits and reproducible baselines. We evaluate multilingual ASR under zero-shot transfer, target-language fine-tuning, donor-language initialization, synthetic supervision, and KenLM-assisted decoding. Target-language supervision substantially improves WER, yet lower edit distance does not always reflect better documentation fidelity: models replace attested Bhili forms with Hindi cognates or delete grammatically meaningful Mundari suffixes while still achieving competitive scores. We introduce **Hindi-Normalization Bias (HNB)** and its alignment-constrained variant **(HNBA)**, **Morphological Fragmentation Rate (MFR)**, and **Suffix Deletion Rate (SDR)** as preservation-oriented diagnostics beyond WER. Human transcriber baselines show that these gaps are not fixed limits. **AdiDhwani** provides the first controlled ASR evaluation framework for these two under-documented Indian languages and supports language-preserving speech recognition research in endangered-language settings.
Anthology ID:
2026.emnlp-main.1707
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
38870–38910
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URL:
https://aclanthology.org/2026.emnlp-main.1707/
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Cite (ACL):
Pooja Singh, M Kaab Bin Shahid, and Sandeep Kumar. 2026. AdiDhwani: Preservation-Oriented ASR for Endangered Bhili and Mundari Languages. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 38870–38910, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
AdiDhwani: Preservation-Oriented ASR for Endangered Bhili and Mundari Languages (Singh et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.1707.pdf