Many hearing aids not only amplify a person’s voice but also filter out distracting background noise. New scientific research has found that female tree frogs have similar functions to hear the courtship of male tree frogs.
During mating season, a pond may be filled with different species of frogs, all of which either make mating sounds or look for potential mates through hearing. With all this noise in the air, one might think that a female frog would have a hard time discerning the bark of its species. However, according to a new study, female American green tree frogs can solve the problem by inflating their lungs.
A team of scientists led by Professor Mark Bee of the University of Minnesota at Twin Cities and Assistant Professor Norman Lee of St. Olaf College, Minnesota, found that when the frog’s lungs were filled with air, its eardrums were slightly compressed. This causes them to vibrate less against sounds within a certain frequency range.
Male American tree frogs are not in this range, while frogs of other species are initially filtered out. As a result, the bark of tree frogs is heard, while the unrelated calls of other species are largely filtered out. Female frogs can continue to use the source of tree frogs’ barks as their home, looking for mates. It is now believed that these frogs can also fine-tune the sensitivity of their “noise reduction” system by changing the amount of air in their lungs.