Beyond human hearing, a cacophony of natural clicks, whistles and hums pass all around us, linking billions of living beings in networks of sound. Mother whales whisper to their young so predators can't hear them. Bees emit unique buzzing signals to distinguish threats from specific predators. Turtle embryos synchronise their collective moment of birth by making sounds through their shells. And unknown fish species buzz to one another in the depths " their very identities one of nature's countless sonic mysteries. What if tapping into these sounds could allow us to not only to learn more about the natural world, but actually help to begin healing it? An emerging appreciation for the biological importance of sound has led to new strategies for environmental conservation. From microscopic larvae lost at sea to birds that travel hundreds of miles from home, conservationists are now starting to use the sounds of nature to guide them back to where they belong. "Sound is so important," says Cheryl Tipp, curator of wildlife and environmental sound at the British Library. "In the natural world, it's used in mating displays, in territorial disputes, as alarm signals." For humans trying to support nature, meanwhile, sound can be used to identify new species, monitor populations and assess the health of ecosystems, she says. There is now a growing interest in the use of sound to accelerate habitat restoration itself, by coaxing certain species to certain locations using their very own sounds.