The acoustic features of the speaker's voice are liable to change due to a number of situational factors, such as success of communication, social distance between the interlocutors etc., and conversational role. The paper aims to find out how pre-defined roles of leader and follower are manifested in the speakers' prosodic features depending on the task they perform: map task vs. card-matching game. In general, information giver tends to speak louder and with higher maximum F0; temporal changes between roles are speaker-dependent. The two types of tasks differ in the prosodic manifestations of conversational roles: in map task the roles of giver and follower differ much more consistently; in card games speakers rarely reveal prosodically well-defined roles.