It’s 50 years since a discovery which helped found the modern conservation movement.

In 1967, an American biologist began listening to sounds from the ocean that he found both spectacular and beautiful. It was the sound of whales.

He released a 1970 album called Songs of the Humpback Whale. It went on to become the most successful natural history recording ever made.

Witness speaks to Dr Roger Payne about a discovery that caught the imagination of the world and helped inspire the Save the Whales movement.

Witness: The stories of our times told by the people who were there.