Design of phonetically balanced SUS test for evaluation of Slovak TTS systems

Development of speech synthesis systems requires the definition of qualitative criterions for evaluation of the output speech. We can evaluate parameters such as intelligibility or naturalness of speech at the output of the system and we can also compare the quality of various systems taking an advantage of the results obtained by these evaluations. One of the most useful evaluation methods is based on the semantically unpredictable sentences, which are being used for the subjective assessment of speech intelligibility. The paper deals with the issue of design of the test that could be used in the evaluation process of Slovak speech synthesis systems. The aim was to analyze and propose a set of semantically unpredictable sentences in Slovak language with focusing on maximizing the phonetic coverage of the proposed set of sentences. Slovak syntactic frames which are based on the most numerous morphological structures extracted from large database of Slovak language text were designed too.