“We look at the way trees look but do not grasp how alive they are.”
These were the words of Alex Metcalf, the world’s only tree listener, who has brought the hidden world of trees to life at Wakehurst.
He demonstrated his unique tree-listening trumpet at the 500-acre estate in Ardingly last Thursday, ahead of his big appearance at Wild Wood Festival over the bank holiday weekend.
School children from Mead Green Infants School in Horley gathered around to hear the distinctive popping sounds of water moving behind the bark of the beautiful oak tree at Kew’s wild botanic garden.
Alex, who has always had a deep appreciation of the natural world, began to wonder whether it was possible to hear the inner workings of a tree when he was studying for a Master’s in product design at the Royal College of Art in 2005 to 2007.
He told the Middy: “I thought, wouldn’t it be interesting to listen to a tree and I found the sound quite interesting and thought people would like it too. It has been quite an amazing journey seeing people’s reactions when they listen.
“Trees are important because they give us oxygen and places like Wakehurst are really important. I love allowing people to experience something they haven’t before. We look at the way trees look but do not grasp how alive they are.
“Watching the incredible reactions on people’s faces when they listen to the sounds of water surging up through a tree’s trunk, is what makes my work a complete privilege.
“You will hear a quiet popping sound that is produced by the water passing through the cells of the xylem tubes and cavitating as it mixes with air on its way upwards. In the background is a loud deep rumbling noise that is produced by the tree moving and vibrating.
“It is this water movement that keeps the tree alive by providing the leaves with the necessary water to turn into sugar as a source of food, and as part of its cooling system on a hot sunny day.
“And standing under the branches with the headphones on gives you a physical connection with the tree and makes it a really immersive experience.”
Alex has been all over the world demonstrating his device, which looks like an old-fashioned hearing trumpet, to a huge audience. He designed and built the instrument as part of his master’s degree assignment.
To be certain that what he was hearing really was the water moving Alex took his creation to Royal Botanic Gardens, Kew. Here he was introduced to Steven Jansen, a Kew scientist who had a PhD in the cavitation of water in the xylem tubes.
He said: “Steven was the expert but even he had never actually heard the water move before. He was blown away by the idea.
“After much discussion we took a tree branch into one of the science laboratories at Kew. Steven made the water travel through the branch at 2 bar / 30 psi.
“He pushed the water through using a pressure bomb and using my listening trumpet I could confirm that the noises I could hear was the water moving behind the bark.”
Alex had his work displayed at the Royal College of Art along with that of other students. But rather than stand his trumpet on a plinth he came up with the novel idea of recording what he was hearing and then hanging lots of headphones from the lower branches of a tree in nearby Kensington Gardens and linked them to the recording.
Alex stood by the tree housing his installation for two weeks and recorded more than a thousand people queuing to hear the hidden life inside this metropolitan tree.
He encouraged people to stand close to the bark and look up into the canopy. Now he shares these sounds with both adults and children at country shows and workshops that he runs throughout the year.
He also has a permanent installation in the Natural History Museum in Los Angeles, America, and has been to Italy to listen to the water inside a tree located inside of a volcano.
In December last year Alex appeared in the BBC programme: Judi Dench: my love of trees.
He said that Dame Judi was completely overcome by the experience. “She was so emotional when she heard what was really going on beneath the bark,” he said.
“It was a moving moment for all of us. Judi said she would never look at trees in the same way again!”
Alex will be sharing his tree listening project at Wakehurst’s Wild Wood Festival this weekend.
The festival offers holiday fun and activities for all the family.
Young adventurers can enjoy tree climbing, letting off steam at Treetrunk Trek and exploring the tree trail. A fire-lighting masterclass is also a must for all those who love the outdoors.
Activities will delight all ages at the festival, which is to celebrate the traditions, ecology, folklore and beauty of our native woodlands.
Wakehurst woodsmen will also be on hand to explain what Kew and Wakehurst do to protect our woodlands for future generations to enjoy.
Entrance to the festival is free of charge with garden admission. Children 16 and under are free. An adult ticket is £12.95.
For more information about Wakehurst and the Wild Wood Festival visit: www.kew.org/visit-wakehurst