Mapudungun-Spanish Speech Translation: A Low-Resource End-to-End System for the IWSLT 2026 Shared Task
Summary
The authors built an end-to-end speech-to-text translation system from Mapudungun (arn), an endangered Indigenous language of Chile and Argentina, into Spanish. It was their entry for Task 1 of the IWSLT 2026 Low-Resource Speech Translation shared task. They used the provided corpus by Duan et al. (2020), about 142 hours of healthcare-themed interviews from the AVENUE project, and adapted NVIDIA's Canary-1B-v2 (FastConformer encoder, Transformer decoder, NeMo framework). The backbone stayed frozen, and only a small linear adapter in the encoder was trained. Canary translates only to and from English, so they used the eng → spa direction and let the "English" source tag stand in for Mapudungun. This relies on the model's existing acoustic knowledge and its ability to generate Spanish. Three runs compared on-the-fly audio augmentation, a plain setup, and filtering out utterances longer than 15 seconds. The filtered run worked best. Absolute scores were very low, and outputs sometimes degenerated into repetitive Spanish phrases. The work shows that cheap adaptation of multilingual foundation models to Indigenous languages is possible but still very limited.
Key points
- Data: The Mapudungun corpus contains 142 h of speech, cleaned from 170 h recorded in 2001–2005. It covers three dialects: Nguluche (~110 h), Lafkenche (~20 h) and Pewenche (~10 h). It uses a 28-grapheme supra-dialectal orthography rather than the Azumchefe standard.
- Method: PEFT with a linear adapter (1024 → 8, Swish activation) reduces trainable parameters from a reported 1.7B to 589k. Other settings were bfloat16 training, Lhotse duration bucketing and lower-cased Spanish without punctuation. The hardware was modest, with GPUs of 24–32 GB.
- Runs: The three runs were Augmented (Main), Vanilla and Filtered (audio ≤15 s). On the development set, the post-submission Filtered* version reached BLEU 3.7 and WER 1.56. The other two runs scored BLEU ~1.0–1.05 and WER 2.3–2.5.
- Official test set: Filtered scored BLEU 0.82 and chrF2++ 14.31. Main scored BLEU 0.73 and chrF2++ 12.70, and Vanilla scored BLEU 0.34 and chrF2++ 6.92.
- Observations:
- Augmentation helped little, probably because the corpus is already noisy.
- The model captured some region-specific words such as huinca and mapuche.
- Two-GPU training was unstable.
- The authors plan to extend the approach to Quechua and Nahuatl.
- Code: github.com/umoqnier/iwstl-low-resource-experiments.
Cite
@inproceedings{martinez2026mapudungun,
title = {{Mapudungun-Spanish Speech Translation: A Low-Resource End-to-End System for the IWSLT 2026 Shared Task}},
author = {Martínez, Diego Alberto Barriga and Gazque, Amilkar and Elizalde, Mikel Segura and Mena, Carlos Daniel Hernandez and Gutierrez-Vasques, Ximena and Ruiz, Ivan Vladimir Meza},
booktitle = {Proceedings of the 23rd International Conference on Spoken Language Translation (IWSLT 2026)},
year = {2026},
doi = {10.18653/v1/2026.iwslt-1.26},
url = {https://doi.org/10.18653/v1/2026.iwslt-1.26}
}References
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