QUALITY EVALUATION OF 5 GERMAN SPEECH SYNTHESIS SYSTEMS

A comprehensive evaluation of five speech synthesis systems covering t hree different auditory evaluation methods is presented. The purpose o f the tests is to assess the signal generation part (i.e. the synthesi zer itself) and the prosody generation module of two rule-based and th ree template-based synthesis systems for German. Different aspects of speech quality and distinct Linguistic levels are addressed by applyin g the following test procedures: the Cluster-Identification Test for t he assessment of segmental intelligibility (TEST1), a Paired Compariso n Test for the measurement of general acceptance at the sentence level (TEST2) and a Category Rating Test using eight attributes at the para graph level (TEST3). First each test is presented separately. Then all test results are related to each other to review the separate interpr etations of the respective results as well as to elicit the main dimen sions of speech quality. Finally, some conclusions are drawn from thes e results regarding speech synthesis improvement. In this context the German Verbmobil project is envisaged, this investigation being a pilo t task of the speech synthesis work group.