FuzhouBench: A Benchmark for Eastern Min Chinese with Tone Sandhi Annotations

Xiaocan Li, Haoyu Lin


Abstract
Eastern Min Chinese (Fuzhou dialect, ISO 639-3 ‘cdo‘) has roughly ten million speakers yet no dedicated paper at any major NLP venue. Four properties make Fuzhou structurally distinct from Mandarin and challenging for current NLP: (1) a tone-sandhi system conditioned on the following syllable’s citation tone, (2) initial-consonant assimilation in non-final positions, (3) systematic literary-colloquial diglossia (45% of frequent characters carry ≥ 2 distinct segmental readings), and (4) substantial lexical divergence (everyday concepts use entirely different morphemes from Mandarin). We release **FuzhouBench**, the first public NLP benchmark for Eastern Min, built on a community-maintained open dictionary: 22,890 word entries with 51,505 standardized Yngping romanizations, 11,276 explicit tone-sandhi annotations, 5,160 explanations, and 3.06 hours of paired dictionary-style audio from two native speakers. We define three tasks (grapheme-to-phoneme, sandhi prediction, definition retrieval) with full baselines. Frontier LLMs score under 3% word-exact on few-shot Yngping G2P, while a LoRA fine-tune on the released pairs reaches 17.2%: learnable, but far from saturated. A symbolic sandhi rule learned from the training pool beats every LLM by up to 18 points; and BM25 collapses from MRR 0.799 to 0.372 when queries shift from dictionary-extracted to colloquial Mandarin, partially recoverable via a two-stage hybrid + cross-encoder pipeline (MRR 0.716). Data, evaluation splits, and code are available at https://github.com/Nang-muoi-sing/FuzhouBench.
Anthology ID:
2026.emnlp-main.618
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
Note:
Pages:
14194–14208
Language:
URL:
https://aclanthology.org/2026.emnlp-main.618/
DOI:
Bibkey:
Cite (ACL):
Xiaocan Li and Haoyu Lin. 2026. FuzhouBench: A Benchmark for Eastern Min Chinese with Tone Sandhi Annotations. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 14194–14208, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
FuzhouBench: A Benchmark for Eastern Min Chinese with Tone Sandhi Annotations (Li & Lin, EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.618.pdf