Female tree frogs found to use their lungs for noise cancellation
A number of hearing aids are now able to amplify one person's voice while filtering out distracting background voices. Well, it turns out that female tree frogs are able to perform a similar task, in order to hear the mating calls of males.
During the mating season, one pond may be filled with different species of frogs, all of which are either calling or listening for potential mates.
With all that noise filling the air, one might think that it would be difficult for a female frog to pick out the calls of males of her species. According to a new study, however, female American green tree frogs (Dryophytes cinereus) are able to manage it by inflating their lungs.
Led by Prof. Mark Bee of the University of Minnesota-Twin Cities – and Asst. Prof. Norman Lee of Minnesota's St. Olaf College – a team of scientists found that when the frog's lungs are full of air, its eardrums are slightly compressed. This causes them to vibrate less in response to sounds within a certain frequency range.
The calls of male American tree frogs fall outside of that range, whereas the calls of other local species are within it. As a result, the tree frog calls are clearly heard, while the irrelevant calls of other species are largely filtered out. The females can then proceed to home in on the source of the tree frog calls, locating a mate.
It is now believed that the frogs are additionally able to fine-tune the sensitivity of their "noise-cancelling" system, by varying the amount of air held in their lungs.
A paper on the research was recently published in the journal Current Biology.