「同步性(synchronicity)」是同步口譯的重要特色，反映了口譯員的認知負荷及訊息處理，進而影響產出品質。口譯研究的文獻多半以「聽譯時間差(ear-voice span, EVS)」來衡量同步性對譯語品質的影響（EVS為原語開始時間和對應譯語開始時間之時長）。然而，「句末時間差(tail-to-tail span, TTS)」對譯語品質的影響可能更大（TTS為原語結束時間和對應譯語結束時間相減之時長）。若句末時間差較短，口譯員的產出和講者下一句原語之間會有較少重疊，讓口譯員保留更多的認知資源來處理新的原語，維持同步性。實務上常見口譯員盡量縮短TTS以提升口譯品質，較短的TTS也代表口譯員的語言較有彈性，訊息處理技巧（如策略性遺漏、壓縮、預測）較佳。本篇技術報告檢視作者在一場會議中，為非英語母語人士之間的問答所做的英譯中同步口譯，分析EVS及TTS與譯語準確度之間的關係。分析顯示，口譯員須隨時注意源語及譯語之間的時間差並盡量縮短句末時間差以維持譯語品質。文末建議口譯教學中應強調時間差的意識，提升語言能力及轉換技巧，以即時分析同步性，提高同步口譯的表現。

Synchronicity is a key feature of simultaneous interpreting (SI). It reflects aspects such as cognitive load and information processing, which would in turn affect output quality. Studies that examined the effect of synchronicity on SI quality often measure the “ear-voice span (EVS)”, the time that elapses between the onset of the source speech and the onset of the corresponding interpretation. Another measure of synchronicity, the “tail-to-tail span (TTS)”, which is the time that elapses between the end of a source speech sentence and the end of the corresponding interpretation, is arguably as important as, if not more than, EVS. A shorter TTS would reduce the amount of time that the interpreter’s output is overlapping with the speaker’s next incoming sentence, helping interpreters preserve more cognitive capacity to process incoming sentences and maintain synchronicity. Anecdotally, shorter TTS produces higher interpretation quality and demonstrates that the interpreter has better language flexibility and information processing skills such as strategic omission, compression, or anticipation. This technical report examined the relationship between both time lag measurements and accuracy of the author’s English to Mandarin Chinese simultaneous interpretation of a Q&A session involving non-native speakers of English. The analysis demonstrates that conscious awareness of the time lag and deliberate actions to shorten TTS contributed to SI quality. The report concluded with pedagogical suggestions on raising students’ awareness of time lag and highlighting the importance of enhancing language proficiency and reformulation techniques to ensure real-time analysis of synchronicity and improve SI performance.