Waves crashing on the shore, footsteps crunching on the forest floor. Stress levels plummet when we immerse ourselves in nature. Nick Luscombe meets the Japanese scientists working to bring the healing power of nature into the heart of the city. Nature's secret, they believe, isn't the sound you can hear, it's the high frequencies you can't hear. Only in our interactions with natural materials are these particular frequencies produced, frequencies that have a direct effect on our bodies.

Producer: Alasdair Cross