Crunching worms, squeaking voles, drumming ants: how scientists are learning to eavesdrop on the sounds of soil

More than 50% of the planet's species live in the earth below our feet, but only a fraction have been identified - so far

Read more: No birdsong, no water in the creek, no beating wings: how a haven for nature fell silent

The sound of an earthworm is a distinctive rasping and scrunching. Ants sound like the soothing patter of rain. A passing, tunnelling vole makes a noise like a squeaky dog's toy repeatedly being chewed.

On a spring day at Rothamsted Research, an agricultural research institution in Hertfordshire, singing skylarks and the M1 motorway are competing for the airways. But the attention here is on the soundscapes underfoot: a rich ecosystem with its own alien sounds. More than half of the planet's species live in the soil, and we are just starting to tune into what they are up to. Beetle larvae, millipedes, centipedes and woodlice have other sound signatures, and scientists are trying to decipher which sounds come from which creatures.