Matthew Sweet discusses talking, speech and having a voice, with Trevor Cox, Professor of Acoustic Engineering at the University of Salford; Rebecca Roache, Senior Lecturer in Philosophy at Royal Holloway, University of London; actress and impressionist Jessica Martin; and Maurice McLeod, social commentator, director of Media Diversified, and Labour councillor for Queenstown Battersea.

Trevor Cox has written Now You're Talking: The Story of Human Conversation from Neanderthals to Artificial Intelligence.

Producer: Luke Mulhall