Team QUESPA System Submission for the IWSLT 2026 Dialectal and Low-resource Speech Translation Task

John E. Ortega, Rodolfo Joel Zevallos, Fabrício Carraro, Stephanny Gabriela Sánchez Bautista, Chad Howe


Abstract
This paper describes the QUESPA team’s speech translation (ST) submissions for the Quechua to Spanish (QUE-SPA) track of the IWSLT 2026 Evaluation Campaign on dialectal and low-resource speech translation. The campaign supports a single submission category, namely unconstrained. This marks our fourth consecutive participation in the IWSLT shared task, building upon prior systems with substantial improvements. Our 2026 submission comprises three unconstrained-only systems. The best-performing system (contrastive 2) extends our strongest model from the previous year by leveraging a high-performing pre-trained language model (PLM) for end-to-end speech translation without cascading, augmented with additional Quechua-Collao text - now made available on the IWSLT GitHub. Fine-tuning Microsoft’s SpeechT5 model in an ST setting, combined with targeted data augmentation, results in a BLEU score of 27.2 on the official evaluation set. Additionally, we evaluate prompt-based machine translation using Gemini, DeepSeek, GPT-5, Claude, and Qwen for the first time. Aside from that, we introduce SIDON, an audio enhancement framework designed to improve audio quality. This paper provides a comparative analysis across our current and three previous IWSLT submissions, with a detailed examination of the impact of synthetic data, unconstrained external resources, and audio enhancement techniques on fine-tuning performance. Our results highlight the complementary role of PLM-based ST, LLM prompting, and ASR enhancement in advancing low-resource speech translation.
Anthology ID:
2026.iwslt-1.5
Volume:
Proceedings of the 23rd International Conference on Spoken Language Translation (IWSLT 2026)
Month:
July
Year:
2026
Address:
San Diego, USA (in-person and online)
Editors:
Elizabeth Salesky, Antonios Anastasopoulos, Matteo Negri, Marcello Federico
Venues:
IWSLT | WS
SIG:
SIGSLT
Publisher:
Association for Computational Linguistics
Note:
Pages:
47–57
Language:
URL:
https://aclanthology.org/2026.iwslt-1.5/
DOI:
Bibkey:
Cite (ACL):
John E. Ortega, Rodolfo Joel Zevallos, Fabrício Carraro, Stephanny Gabriela Sánchez Bautista, and Chad Howe. 2026. Team QUESPA System Submission for the IWSLT 2026 Dialectal and Low-resource Speech Translation Task. In Proceedings of the 23rd International Conference on Spoken Language Translation (IWSLT 2026), pages 47–57, San Diego, USA (in-person and online). Association for Computational Linguistics.
Cite (Informal):
Team QUESPA System Submission for the IWSLT 2026 Dialectal and Low-resource Speech Translation Task (Ortega et al., IWSLT 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.iwslt-1.5.pdf