IntroductionTo foster effective human-agent interactions, designers must understand how vocal cues influence the perception of agent personality and the role of user-agent alignment in shaping these perceptions. In this work, we examine whether users can perceive extroversion in voice-only artificial agents and how perceived personality relates to user-agent synchrony.MethodsWe conducted an exploratory study with 388 participants, who evaluated four synthetic voices derived from human recordings, varying by gender (male, female) and personality expression (introverted, extroverted).ResultsOur findings suggest that participants were able to differentiate perceived extroversion across the female voice conditions, but not consistently across the male voice conditions. We also observed preliminary evidence consistent with perceived personality synchrony, particularly in participants' evaluations of the first agent encountered. These findings represent an initial step toward understanding personality synchrony in voice-based human-agent interactions. Because each experimental condition was represented by a single synthesized voice and no objective acoustic validation of the intended personality manipulation was conducted, these findings should be interpreted within the exploratory scope of this study.DiscussionWe discuss the implications of these findings while considering the limitations of stimulus diversity and voice representation, and outline implications for the design of voice-based agents, particularly regarding the interaction between gender, personality perception, and initial user impressions. This paper contributes exploratory evidence and methodological insights for investigating the interplay of user-agent personality and gender synchrony in the design of human-agent interactions.