CATENG Submission for the IWSLT 2026: Dialectal and Low-resource Speech Translation Task
Summary
This paper describes the CATENG team's entries to the IWSLT 2026 shared task on dialectal and low-resource speech translation, which covers translating spoken Catalan into English text. Catalan has good text resources but is still underserved in speech technology. Its Eastern and Western varieties, along with mixing with Spanish, make recognition harder. The team submitted three unconstrained systems, trained on the roughly 15-hour IWSLT 2026 Catalan dataset plus external parallel text.
Two of the systems are cascades that feed a fine-tuned NLLB-200 translation model. The first uses a Mamba-based recognizer (ConMamba, the primary run). The second uses a Catalan-adapted Whisper-v3, further tuned on the task data. The third system is a direct SpeechT5 model trained with audio augmentation.
The Whisper-v3 cascade scored highest, and both pipelines beat the end-to-end model. Because the cascades share the same MT component, the authors conclude that recognition quality, rather than translation, is the limiting factor. The Mamba-based recognizer was already close to Whisper-v3. This edition is also the first in which Catalan appears as a source language in the track.
Key points
- Official scores: Whisper-v3 + NLLB reached 44.7 BLEU / 65.1 chrF, ConMamba + NLLB reached 43.2 / 64.3, and SpeechT5 (end-to-end) reached 41.3 / 63.1. The gap between best and worst is 3.4 BLEU.
- The MT component is NLLB-200 (1.3B), fine-tuned for CA–EN with these settings:
- sequences up to 128 tokens
- 10 epochs, batch size 8
- beam search with 5 beams
- fixed seed 65
- The Whisper run starts from the Projecte AINA checkpoint
faster-whisper-large-v3-ca-3catparla. It is then fine-tuned on the task's Catalan transcriptions as ASR targets. - SpeechT5 has a 12-layer encoder and a 6-layer decoder and was pretrained on 960 h of LibriSpeech. It was augmented with nlpaug (noise, temporal distortion, signal perturbation), which doubled the training audio.
- The dataset is public on GitHub (
rjzevallos/IWSLT_2026_Catalan_Dataset). The constrained setting no longer exists in this track.
Cite
@inproceedings{zevallos2026cateng,
title = {{CATENG Submission for the IWSLT 2026: Dialectal and Low-resource Speech Translation Task}},
author = {Zevallos, Rodolfo Joel and Casals, Marc and Ortega, John E. and Carraro, Fabrício and Buitrago, Pol and Cámbara, Guillermo},
booktitle = {Proceedings of the 23rd International Conference on Spoken Language Translation (IWSLT 2026)},
year = {2026},
doi = {10.18653/v1/2026.iwslt-1.18},
url = {https://doi.org/10.18653/v1/2026.iwslt-1.18}
}References
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