This paper analyzes the features of monotonic translations, which follow the word order of the source language, in simultaneous interpreting (SI). The word order differences are one of the biggest challenges in SI, especially for language pairs with significant structural differences like English and Japanese. We analyzed the characteristics of monotonic translations using the NAIST English-to-Japanese Chunk-wise Monotonic Translation Evaluation Dataset and found some grammatical structures that make monotonic translation difficult in English-Japanese SI. We further investigated the features of monotonic translations through evaluating the output from the existing speech translation (ST) and simultaneous speech translation (simulST) models on NAIST English-to-Japanese Chunk-wise Monotonic Translation Evaluation Dataset as well as on existing test sets. The results suggest that the existing SI-based test set underestimates the model performance. We also found that the monotonic-translation-based dataset would better evaluate simulST models, while using an offline-based test set for evaluating simulST models underestimates the model performance.

翻译：本文分析了同声传译中遵循源语言词序的单调翻译特征。词序差异是同声传译面临的主要挑战之一，对于英语和日语这类结构差异显著的语言对尤为突出。我们利用NAIST英日分块单调翻译评估数据集分析了单调翻译的特征，发现了若干导致英日同声传译中单调翻译困难的语法结构。通过评估现有语音翻译模型及同声语音翻译模型在NAIST英日分块单调翻译评估数据集及既有测试集上的输出表现，我们进一步探究了单调翻译的特性。结果表明，现有基于同声传译的测试集低估了模型性能。我们还发现基于单调翻译的数据集能更有效地评估同声语音翻译模型，而使用离线测试集评估同声语音翻译模型则会低估其性能。