With the liberalisation of the airwaves and the rising use of mobile phones since the 2000s, call- and text-in shows have become popular and lively features on broadcast media in Eastern Africa. Amidst expanding possibilities for listeners to speak and contribute to live radio broadcasts, new ways of imagining the position of the audience emerge. The audience is not simply comprised of passive listeners of publicly broadcast information, but actively engaged in contributing and reacting to what is aired. Yet the nature and political potential of the ‘audience-public’ is not straightforward. Interactive radio and TV shows are not just introducing specific audience members into the discussion, but who they are, what they represent, their influence and contribution to the space are uncertain. As audience members engage, those who manage and shape the broadcast must imagine, interpret and respond. Each participant in the discussion –whether listening, or involved in the station – producing, hosting, etc. – must come to terms with the nature of the interaction, Who is engaged? How should they respond? What are their reasons for being engaged and how might the introduction of this indeterminate audience-public relate to their intentions? Given the plurality of subjectivities, information, roles and intentions of those involved, the audience and why it matters can be imagined in multiple and competing ways. This paper interrogates how different actors involved in the radio broadcast imagine and respond to audience participation, and how these imaginaries become politically significant. This paper draws predominantly on interview and observation data on the perspectives of station hosts, guests and frequent callers of selected media houses and interactive broadcast shows in Zambia and Kenya. It examines the dynamic, plural and conflicting ways in which the audience is being reconstructed as an active ‘public’. In so doing, it shows the centrality of the imagined audience in the construction of the broadcast as a ‘public’, specifically how the indeterminate audience becomes the basis for competing imaginaries about power, authority and belonging. The political significance of the ‘audience-public’, it is argued, lies in the very fact that multiple and competing imaginaries are at play, which are invested in by actors pursuing diverse ends and thereby create tangible political effects.