To find her mate amidst a cacophony of frog croaks, groans, squeaks and trills, a female green tree frog just needs to take a deep breath.
During mating season, ponds resound with the sounds of hundreds of males from many different species crying out to potential mates. Homing in on eligible males against all this crooning presents a significant challenge for females, akin to straining to understand a friend at a raucous party. But by simply inflating her lungs, an American green tree frog (Hyla cinerea) can make her eardrums less sensitive to the sounds of other species, researchers report March 4 in Current Biology.
“We think the lungs are working a bit like some noise-canceling headphones,” says Norman Lee, a neuroethologist at St. Olaf College in Northfield, Minn., allowing females to filter out environmental noise at the eardrum itself.
An eardrum is just taut tissue that vibrates when sound waves hit it, ultimately translating the bleating and buzzing of the natural world into signals that get processed in the brain. To mammals like us, eardrums and lungs seem completely unrelated. But there’s a direct connection, via an open space, between the body parts in frogs that runs through the throat and into the frogs’ head. That lets frog eardrums pick up sound from outside the ear and also register vibrations from the lungs.