One study reveals that a frog species, like noise canceling headphones, must inflate their lungs to reduce background noise so that they can hear their potential partner’s calls.
For their study, the researchers took vibration measurements of 25 frogs using a laser system while inflating and deflating the frogs’ lungs.
The inflated lungs remained responsive to the calls of the same species, while selectively reducing the capacity of the eardrum at sound frequencies unrelated to the calls of different species.
Essentially, a female American green tree frog can hear males of its kind regardless of the bulging of its lungs, but it can also reduce its sensitivity to other unwanted calls.
Inflated lungs make it difficult for the tree frog to hear calls from other species that it is not interested in, while gaining the ability to hear their own species’ calls as they are, making them easier to find.
This naturally evolving technique depends on the intelligent lung-to-ear sound transmission pathway unique to amphibians.
“Essentially, what female frogs do is wear noise-canceling headphones,” said Professor Mark Bee.
“Their lungs seem to suppress the vibrations of the eardrum. Thus, it helps other frog species to reduce the different frequency levels in mating calls. “
This technique, called ‘spectral contrast enhancement’, highlights frequencies in the spectrum of a man’s call over noise at adjacent frequencies.
In inflated lungs, the frog’s eardrums vibrate less in response to unwanted sounds in a certain frequency range.
The lungs eliminate noise by reducing eardrum vibrations.
“This is similar to the signal processing algorithms for spectral contrast enhancement applied in some hearing aids and cochlear implants,” Bee said.
“We believe that the physical mechanism by which this occurs is similar in principle to the way noise canceling headphones work.”
Noise disrupts effective vocal communication in animals. It’s like researchers trying to salute when people have a hard time hearing each other at parties.
For frogs, a female must find a male of her own kind among the irrelevant background noise, including the sounds of other frog species breeding at the same time and speaking in the same choir.
The researchers chose to examine data from the American green tree frog, which is highly common with other frog species.
Overall, about 42 different frog species ‘call out’ with the green tree frog, meaning they are part of a mixed choir of mating calls.
Frogs have a unique vocal tract that can transmit sounds from their air-filled lungs to their air-filled middle ears via the glottis, oral cavity, and eustachian tubes.
However, the precise function of this lung-to-ear sound transmission pathway was a mystery.
Minnesota, St. “The lungs cancel out the eardrum’s response to noise, especially some of the noise generated when males of many other species are calling at the same time,” said Norman Lee, author of the study from Olaf College.
Work Current Biology‘de published.
/ Green Tree Frog Uses A Natural Headset Technology By Inflating Its Lung /
