Large Language Models Are Efficient Learners as Zero-Shot Speech Translators

Significant progress has recently been made in combining Speech Foundation Models (SFMs) and Large Language Models (LLMs) into a unified model to tackle Speech-to-Text Translation (ST) tasks. However, fine-tuning LLMs to adapt to specific downstream tasks requires substantial resources, which is often infeasible. Therefore, this study proposes using Chain-of-Thought (CoT)-based LLMs to perform error correction on Automatic Speech Recognition results followed by translation into the target language. This approach combines SFMs and LLMs in a lightweight manner without fine-tuning or large parallel corpora. Additionally, through our proposed Translation Graph CoT (TGCoT), which involves iterative feedback and Back Translation, the model can self-check when errors are detected, effectively reducing error accumulation during the multi-step CoT reasoning process and thereby improving translation accuracy. Finally, extensive experiments across languages and models demonstrate the superiority and robustness of the proposed method. The results show that the proposed approach better unleashes LLM capabilities and adapts to downstream ST tasks with minimal resources.