In smooth and cooperative human-to-human conversations, the prosody as pitch is synchronized between speakers. From this, it is expected that there are some relations between various prosodic changes and the impressions of the conversations. It is necessary to understand what factors are involved in meaning the conversation smooth and lively. In this paper, we analyzed the correlation between the fundamental frequency's synchrony tendency or overlap frequency, and subjective measures of "liveliness" and "familiarity" in human-to-human dialog. As a result, when the prosodic change of speakers synchronized well, it seemed the dialog became familiar, lively, and frank, and the speakers were in agreement. It is shown that the impression signifiers of the conversation are able to be evaluated with only the use of prosodic information.
