Hierarchical Policy Optimization for Simultaneous Translation of Unbounded Speech

Fuente: arXiv
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Autori principali: Ouyang, Siqi, Ding, Shuoyang, Hrinchuk, Oleksii, Lavrukhin, Vitaly, Yan, Brian, Ginsburg, Boris, Li, Lei
Natura: Preprint
Pubblicazione: 2026
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author Ouyang, Siqi
Ding, Shuoyang
Hrinchuk, Oleksii
Lavrukhin, Vitaly
Yan, Brian
Ginsburg, Boris
Li, Lei
author_facet Ouyang, Siqi
Ding, Shuoyang
Hrinchuk, Oleksii
Lavrukhin, Vitaly
Yan, Brian
Ginsburg, Boris
Li, Lei
contents Simultaneous speech translation (SST) generates translations while receiving partial speech input. Recent advances show that large language models (LLMs) can substantially improve SST quality, but at the cost of high computational overhead. To reduce this cost, prior work reformulates SST as a multi-turn dialogue task, enabling full reuse of the LLM's key-value (KV) cache and eliminating redundant feature recomputation. However, this approach relies on supervised fine-tuning (SFT) data in dialogue form, for which few human annotations exist, and existing synthesis methods cannot guarantee data quality. In this work, we propose a Hierarchical Policy Optimization (HPO) approach that post-train models trained on imperfect SFT data. We introduce a hierarchical reward that balances translation quality and latency objectives. Experiments on English to Chinese/German/Japanese demonstrate improvements of over +7 COMET score and +1.25 MetricX score at a latency of 1.5 seconds. Comprehensive ablation studies further validate the effectiveness of different quality rewards, hierarchical reward formulations, and segmentation strategies. Code can be found here https://github.com/owaski/HPO
format Preprint
id arxiv_https___arxiv_org_abs_2604_21045
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Hierarchical Policy Optimization for Simultaneous Translation of Unbounded Speech
Ouyang, Siqi
Ding, Shuoyang
Hrinchuk, Oleksii
Lavrukhin, Vitaly
Yan, Brian
Ginsburg, Boris
Li, Lei
Computation and Language
Simultaneous speech translation (SST) generates translations while receiving partial speech input. Recent advances show that large language models (LLMs) can substantially improve SST quality, but at the cost of high computational overhead. To reduce this cost, prior work reformulates SST as a multi-turn dialogue task, enabling full reuse of the LLM's key-value (KV) cache and eliminating redundant feature recomputation. However, this approach relies on supervised fine-tuning (SFT) data in dialogue form, for which few human annotations exist, and existing synthesis methods cannot guarantee data quality. In this work, we propose a Hierarchical Policy Optimization (HPO) approach that post-train models trained on imperfect SFT data. We introduce a hierarchical reward that balances translation quality and latency objectives. Experiments on English to Chinese/German/Japanese demonstrate improvements of over +7 COMET score and +1.25 MetricX score at a latency of 1.5 seconds. Comprehensive ablation studies further validate the effectiveness of different quality rewards, hierarchical reward formulations, and segmentation strategies. Code can be found here https://github.com/owaski/HPO
title Hierarchical Policy Optimization for Simultaneous Translation of Unbounded Speech
topic Computation and Language
url https://arxiv.org/abs/2604.21045