We are surrounded by sounds all the time, but we tend not to hear them; our brains are very good at editing what our ears pick up. If we stop for a moment to listen, there they are: the ticking clock, traffic noise, fragments of conversation, a passing plane. These are examples of what the American composer John Cage called “illegal harmony”.

In response to the noisiest century in history, modern composers have consistently flown in the face of musical orthodoxy. As technology has changed at an unprecedented rate, so have musical styles – sometimes to the dismay of audiences and critics.

In Illegal Harmonies, Andrew Ford charts the course of music in the concert hall and opera house over the last hundred years, linking it to developments in literature, theatre, cinema and the visual arts, and to popular music from Irving Berlin to the Beatles to rap. The result is a stimulating, provocative and informative cultural history. This revised third edition includes a new preface and extended epilogue, bringing the story into the twenty-first century.