In 1945, W. Averell Harriman, US Ambassador to the Soviet Union, was presented with a carved wooden plaque of the Great Seal of the United States as a 'gesture of friendship' by a delegation from the Young Pioneer Organization of the Soviet Union. Unbeknownst to him, one of the first covert listening devices - the 'Great Seal Bug' as it came to be known - was secreted within it and was subsequently used to listen in on his conversations for the next six years. This book uses remarkable tales like this to tell the story of the development of modern audio surveillance and the way in which it has influenced the development of today's artificial intelligence. Beginning with the tale of the Great Seal Bug and speculating forward, the book traces an arc through to the present day in which Pegasus spyware can record our calls, copy messages and secretly film us, before moving into a near future in which AIs can listen to things we have not yet said. Exploring how mass forms of audio intelligence now inform artificial intelligence through speakers and appliances brought into the home, it examines technologies such as mobile phones, children’s toys and even IoT baby monitors to show that the urge to listen to everything that has ever been uttered is scored deeply into the technological operating system of Western culture.