ASSESSMENT OF SPEECH SYNTHESIS TECHNOLOGY AS A HUMAN INTERFACE

1)从1）可懂度，2）自然度和3）对个别应用的适用性的观点对合成语音质量进行了评估。2）从可懂度研究中发现：（1）双音节音素的可懂度分数比单音节音素的可懂度分数更重要，因为双音节音素与句子的可懂度分数的关系比单音节音素更密切。(2)我们还发现了一个适当的程序来对异常句子进行知觉判断。3）我们发现，合成语音的自然度评估不仅应由普通人来做，而且应由受过语音学训练的受试者来做，因为自然度测试是为了测量合成语音中实际语音表现的程度。4）根据合成语音对于特定应用的适当语音质量，已经实验性地研究了合成语音的适用性。语音质量在平均频谱形状和基频方面是不同的。我们发现，适当的平均频谱形状取决于合成语音是在安静的房间里还是在办公室里被听到，而适当的平均基频的变化取决于它是长时间使用还是短时间使用。

1) Assessment of synthetic speech quality has been made from the viewpoint of 1) intelligibility, 2) naturalness, and 3) suitability to individual applications. The suitability can be stated in terms of application purpose, the users, and the environments.2) From the intelligibility study, we found the followings: (1) Intelligibility scores of phonemes in bisyllables are more essential than the ones in monosyllables in the sense that the formers are more closely related to the intelligibility score of the sentence than the latters. (2) The word intelligibility should be measured in the anomalous sentence context as shown at Haskins Laboratories, U.S.A. We also found an adequate procedure for the perceptual judgments of anomalous sentences.3) We have found that the naturalness assessment of synthetic speech should be made not only by ordinary people but by the subjects who are trained in phonetics, since the naturalness test is to measure the degree of actual phonetic manifestation in synthetic speech.4) Suitability of the synthetic speech has been experimentally studied in terms of the appropriate voice quality of the synthetic speech for particular applications. The voice quality was varied in terms of the average spectral shape and the fundamental frequency. We found that the appropriate average spectral shape depends upon whether the synthetic speech is to be heard in a quiet room or in an office and that an adequate average fundamental frequency changes depending upon whether it is to be used for long hours or for a short period of time.