Intelligibility of Machine Translation Output in Speech Synthesis

One use of text-to-speech synthesis (TTS) is as a component of speech-to-speech translation systems. The output of automatic machine translation (MT) can vary widely in quality, however. A synthetic voice that is extremely intelligible on naturally-occurring text may be far less intelligible when asked to render text that is automatically generated. In this paper, we compare the quality of synthesis of naturally-occurring text and its MT counterpart. We find that intelligibility of TTS on MT output is significantly lower than on either naturally-occurring text or semantically unpredictable sentences, and explore the reasons why