Effect of melodic properties on speakers' perceived credibility

Pitch range and prosodic phrasing are known to be among the factors influencing a speaker's perceived quality. Previous research suggests that greater melodic variability generally contributes to more positive ratings. However, the importance of different factors seems to be language-specific and may also be context-dependent. The objective of this thesis is to examine the influence of melodic properties of speech on the perceived credibility of Czech speakers in a political context. For the purposes of the study, ten former male politicians who are no longer politically active were selected. Their credibility was assessed using two versions of a perception test, each containing ten original recordings and ten recordings with applied melodic manipulation. A total of 94 respondents participated in the test. Our results indicate that Czech listeners tend to prefer speech with lower melodic variability. The findings also suggest that pitch range is not a decisive factor for perceived credibility, as implicated by a high interpersonal variability of responses. The existence of other determining factors is also evidenced by the results of an additional survey, which was conducted on 13 speakers of other languages. Keywords: melodic variability, pitch range, prosodic phrasing, Czech, perceived...