Abstract
We present HydraQE, our contribution to the IWSLT 2026 Speech Translation Metrics shared task. HydraQE is an end-to-end, reference-free quality estimation (QE) system for speech translation built on a Qwen3-ASR backbone, which accepts source audio and a translation hypothesis as joint input. Hidden states from all backbone layers are combined via a sparsemax scalar mix, then re-encoded by a bidirectional Transformer for full cross-modal interaction. To address the scarcity of human-annotated speech translation data, three independent prediction heads are trained on complementary supervision signals: human direct assessment (DA) annotations, MetricX-24 pseudo-labels, and xCOMET pseudo-labels. We train on a combination of synthetically corrupted examples and silver pseudo-labeled machine translation outputs, using a curriculum that begins on synthetic and silver data and gradually shifts toward human-annotated examples. HydraQE outperforms cascaded text-based baselines and prior direct speech QE systems, demonstrating that end-to-end speech translation QE is competitive with cascaded approaches.- Anthology ID:
- 2026.iwslt-1.37
- Volume:
[Proceedings of the 23rd International Conference on Spoken Language Translation (IWSLT 2026)](/volumes/2026.iwslt-1/)- Month:
- July
- Year:
- 2026
- Address:
- San Diego, USA (in-person and online)
- Editors:
Elizabeth Salesky,Antonios Anastasopoulos,Matteo Negri,Marcello Federico- Venues:
[IWSLT](/venues/iwslt/)|[WS](/venues/ws/)- SIG:
[SIGSLT](/sigs/sigslt/)- Publisher:
- Association for Computational Linguistics
- Note:
- Pages:
- 323–331
- Language:
- URL:
[https://aclanthology.org/2026.iwslt-1.37/](https://aclanthology.org/2026.iwslt-1.37/)- DOI:
- Cite (ACL):
- Kevin Krahn and Eric Fosler-Lussier. 2026. HydraQE: OSU’s Submission for the IWSLT 2026 Speech Translation Metrics Shared Task. InProceedings of the 23rd International Conference on Spoken Language Translation (IWSLT 2026), pages 323–331, San Diego, USA (in-person and online). Association for Computational Linguistics. - Cite (Informal):
[HydraQE: OSU’s Submission for the IWSLT 2026 Speech Translation Metrics Shared Task](https://aclanthology.org/2026.iwslt-1.37/)(Krahn & Fosler-Lussier, IWSLT 2026)- PDF:
[https://aclanthology.org/2026.iwslt-1.37.pdf](https://aclanthology.org/2026.iwslt-1.37.pdf)