SONAR-SLT: Multilingual Sign Language Translation via Language-Agnostic Sentence Embedding Supervision

Yasser Hamidullah, Shakib Yazdani, Cennet Oguz, Josef Van Genabith, Cristina España-Bonet


Abstract
Sign language translation (SLT) is typically trained with text in a single spoken language, which limits scalability and cross-language generalization. Earlier approaches have replaced gloss supervision with text-based sentence embeddings, but up to now, these remain tied to a specific language and modality. In contrast, here we employ language-agnostic, multimodal embeddings trained on text and speech from multiple languages to supervise SLT, enabling direct multilingual translation. To address data scarcity, we propose a coupled augmentation method that combines multilingual target augmentations (i.e. translations into many languages) with video-level perturbations, improving model robustness. Experiments show consistent BLEURT gains over text-only sentence embedding supervision, with larger improvements in low-resource settings. Our results demonstrate that language-agnostic embedding supervision, combined with coupled augmentation, provides a scalable and semantically robust alternative to traditional SLT training.
Anthology ID:
2025.wmt-1.18
Volume:
Proceedings of the Tenth Conference on Machine Translation
Month:
November
Year:
2025
Address:
Suzhou, China
Editors:
Barry Haddow, Tom Kocmi, Philipp Koehn, Christof Monz
Venue:
WMT
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
301–313
Language:
URL:
https://aclanthology.org/2025.wmt-1.18/
DOI:
Bibkey:
Cite (ACL):
Yasser Hamidullah, Shakib Yazdani, Cennet Oguz, Josef Van Genabith, and Cristina España-Bonet. 2025. SONAR-SLT: Multilingual Sign Language Translation via Language-Agnostic Sentence Embedding Supervision. In Proceedings of the Tenth Conference on Machine Translation, pages 301–313, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
SONAR-SLT: Multilingual Sign Language Translation via Language-Agnostic Sentence Embedding Supervision (Hamidullah et al., WMT 2025)
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PDF:
https://aclanthology.org/2025.wmt-1.18.pdf