This paper describes evaluations of the readability of visualized speech represented by integrating several speech parameters. In the first test, a closed subset of a small vocabulary (75 words: nouns) uttered by four male speakers was examined. Next, the vocabulary was expanded to a medium size (520 words: nouns, adjectives, verbs, and adverbs) uttered by 10 males. Finally, we conducted a systematic test to analyze the influence of vocabulary size, defective representation of a parameter, and real-time representation on the readability of utterances by 10 males and 10 females. The results showed that readability of the visualized speech was almost unaffected by differences among speakers. Moreover, words from the small vocabulary (75-120) were readable in real time because subjects could rapidly grasp the vocabulary through the repetition of randomized words uttered by various speakers during tests even without being told correct answers.
