Simultaneous translation is a task in which the translation begins before the end of an input speech segment. Its evaluation should be conducted based on latency in addition to quality, and for users, the smallest possible amount of latency is preferable. Most existing metrics measure latency based on the start timings of partial translations and ignore their duration. This means such metrics do not penalize the latency caused by long translation output, which delays the comprehension of users and subsequent translations. In this work, we propose a novel latency evaluation metric for simultaneous translation called \emph{Average Token Delay} (ATD) that focuses on the duration of partial translations. We demonstrate its effectiveness through analyses simulating user-side latency based on Ear-Voice Span (EVS). In our experiment, ATD had the highest correlation with EVS among baseline latency metrics under most conditions.

同时翻译是一种在输入语音片段结束之前开始的任务。我们提出了一种用于同时翻译的新颖延迟评估指标——平均令牌延迟(ATD)，该指标侧重于部分翻译的持续时间。通过基于耳-声跨度(EVS)进行用户端延迟模拟的分析，我们证明了该指标的有效性。在我们的实验中，ATD与EVS在大多数条件下具有最高的相关性。

平均令牌延迟：同时翻译的时延度量