Sequence-to-Sequence Models for Emphasis Speech Translation

Speech-to-speech translation (S2ST) systems are capable of breaking language barriers in cross-lingual communication by translating speech across languages. Recent studies have introduced many improvements that allow existing S2ST systems to handle not only linguistic meaning but also paralinguistic information such as emphasis by proposing additional emphasis estimation and translation components. However, the approach used for emphasis translation is not optimal for sequence translation tasks and fails to easily handle the long-term dependencies of words and emphasis levels. It also requires the quantization of emphasis levels and treats them as discrete labels instead of continuous values. Moreover, the whole translation pipeline is fairly complex and slow because all components are trained separately without joint optimization. In this paper, we make two contributions: 1) we propose an approach that can handle continuous emphasis levels based on sequence-to-sequence models, and 2) we combine machine and emphasis translation into a single model, which greatly simplifies the translation pipeline and make it easier to perform joint optimization. Our results on an emphasis translation task indicate that our translation models outperform previous models by a large margin in both objective and subjective tests. Experiments on a joint translation model also show that our models can perform joint translation of words and emphasis with one-word delays instead of full-sentence delays while preserving the translation performance of both tasks.