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Beneath the surface of healthy soils, an unexpected world of sound emerges.

A recent study from Flinders University in Australia found that the biodiversity of soil can be measured by the barely audible sounds produced by tiny creatures, such as ants, worms and beetles.

These sounds – described as clicks, pops, and bubbling noises – are being recorded through new technology in the emerging field of “ecoacoustics” that can help monitor soil biodiversity and health without disturbing the ecosystem.

Lead researcher Dr. Jake Robinson compared the method to a doctor’s examination.

“We’re just doing a health assessment of the soil, but instead of a heartbeat, it’s the invertebrates in the soil making different sounds that we can detect,” he explained to Cosmos Magazine. “This helps us diagnose how healthy the soil is.”

The researchers conducted their experiments in South Australia’s Adelaide Hills, using microphones and sound attenuation chambers to record soundscapes in soils across three types of plots – recently cleared land, plots revegetated 15 years ago, and undisturbed land.

The results showed that revegetated and undisturbed plots were much louder and more diverse in sound than those in degraded soils, indicating a greater abundance of life.

To confirm these findings, they also manually counted soil organisms to cross-validate their data and determined that higher acoustic diversity correlates with richer biodiversity underground.

The study also uncovered that different organisms produce unique sound signatures based on their size, shape and activity. For example, millipedes create a tapping sound as they move, while snails produce a gliding, softer noise.

The researchers believe that the developing field of ecoacoustics will prove integral in soil restoration efforts.

By listening to the soil, scientists can determine whether restoration techniques are working, and even detect invasive species or environmental disturbances.

“Restoring and monitoring soil biodiversity has never been more important,” Robinson said in a press release.

With 75 percent of the world’s soils degraded, these findings offer a promising new tool for conservationists and ecologists alike – proving that sometimes, the key to understanding the environment lies in simply listening.