Inside a Victorian sewer, with fat deposits sliding off the ceiling and disappearing down the back of his shirt, Trevor Cox had an epiphany. Listening to the strange sound of his voice reverberating inside the sewer, he wondered where else in the world he could experience unusual and surprising noises.

As an acoustic engineer, Trevor started his career tackling unwanted noises, from clamour in the classroom to poor acoustics in concert halls. But his jaunt inside a sewer sparked a new quest to find and celebrate the 'sonic wonders of the world'.

In this episode he shares these sounds with Jim Al-Khalili and discusses the science behind them.

Producer: Michelle Martin.