While "voice" is frequently invoked in discussions of pupils' agency and empowerment, less attention has been paid to the dialogic dynamics of children's voices and the sociocultural features shaping their emergence. Drawing on linguistic ethnographic research involving recent recordings of 10- and 11-year-old children's spoken language experience across the school day, this paper examines how pupils' voices are configured within institutional interactional contexts which render particular kinds of voice more or less hearable and convey different kinds of value. Analysis shows how children appropriate and reproduce the authoritative voices of education, popular culture and parents in the course of their induction into social practices. At the same time, they also express varying degrees of commitment to these voices and orchestrate their own and other people's voices within accounts and anecdotes, making voice appropriation an uneven, accumulative process shot through with the dynamics of personal and peer-group experience. The examination of children's dialogue from different contexts across the school day highlights the situated semiotics of voice and the heteroglossic development of children's speaking consciousness.