Dr Helen Czerski examines the extraordinary messages sound waves carry and how they help us understand the world around us.

Visiting a hidden location buried beneath the hills of Scotland, Helen experiences some of the most extreme acoustics in the world. Here she learns just how much information can be carried by sound. She discovers how sound has driven the evolution of truly incredible biological systems and complex relationships between creatures that exploit sound for hunting - and escaping from predators. Helen demonstrates how sound waves diffract (bend around objects) and in doing so help us sense danger and locate it.

Through the story of a cochlea implant patient Helen explores the complicated way our ears can translate sound waves - a physical vibration in the air - into an electrical signal our brain can understand.

Helen explains how we are not limited to passively detecting sound waves, we can also use them to actively probe the world. From detecting submarines to uncovering the secrets of our planet, sound waves are instrumental in revealing things hidden from the world of light. On the cold North Sea, Helen investigates how marine archaeologists are using sound waves to uncover the remarkable human stories buried beneath the sea. Yet we are not limited to using sound waves here on Earth, as Helen explains how sound has been used to better understand distant, alien worlds in the outer solar system. Show less