The amount of labeled data to train models for speech tasks is limited for most languages, however, the data scarcity is exacerbated for speech translation which requires labeled data covering two different languages. To address this issue, we study a simple and effective approach to build speech translation systems without labeled data by leveraging recent advances in unsupervised speech recognition, machine translation and speech synthesis, either in a pipeline approach, or to generate pseudo-labels for training end-to-end speech translation models. Furthermore, we present an unsupervised domain adaptation technique for pre-trained speech models which improves the performance of downstream unsupervised speech recognition, especially for low-resource settings. Experiments show that unsupervised speech-to-text translation outperforms the previous unsupervised state of the art by 3.2 BLEU on the Libri-Trans benchmark, on CoVoST 2, our best systems outperform the best supervised end-to-end models (without pre-training) from only two years ago by an average of 5.0 BLEU over five X-En directions. We also report competitive results on MuST-C and CVSS benchmarks.

本文利用无监督语音识别、机器翻译与语音合成技术，探讨实现无标注数据建立语音翻译系统的方法，通过管道方法或生成伪标签，对端到端语音翻译模型进行训练。同时，提出一种无监督域自适应方法，能够提供一定的性能提升。实验结果表明，本文提出的无监督语音翻译方法，在Libri-Trans基准测试的BLEU分数上超过以前报告的无监督效果的3.2个点，在CoVoST2数据集上，本文的最佳系统相对于最佳监督学习的端到端模型（无预训练），在五个语种（X-En）上平均提高5.0个BLEU分数。在MuST-C和CVSS基准测试上，本文也取得了有竞争力的结果。

简单有效的无监督语音翻译