National Geographic recently reported that a group of researchers at University of Illinois discovered that the male Chinese Torrent frog is able to block out background noise in their environment in order to localize (pinpoint) the direction of an ultrasonic love call from a female torrent frog with uncanny accuracy.
Hearing Open and Closed
Most exciting to researchers is the way this unusual amphibian can actually tune out sounds and tune them back in as needed, simply by closing and opening its ears.
Albert Feng, co-author of the study at the University of Illinois, told National Geographic, "This was contrary to everything that we know about [the frog's] auditory system." Feng and his team of collaborators believe that the torrent frog, which lives near rushing streams and noisy waterfalls, has developed the ability to block out background noise so the critter can hear ultra-sonic calls from potential mates and rivals.
Further study reveals that the torrent frogs actively open and close their ears, in turn closing down the Eustachian tube - the narrow canal that connects ears and mouth. With the Eustachian tubes closed, the frogs' ability to hear high-pitched, ultra-sonic signals improves significantly because low frequency sounds (those rushing waterfalls) fade into the background.
More Studies from the Proceedings of the National Academy of Sciences
James Saunders is an auditory expert out of the University of Pennsylvania who's studied the torrent frogs' unique ability to tune out frequencies. "This mechanism," Saunders stated, "is truly unique within the animal kingdom."
Saunders points out that the ability to select frequencies in humans is actually a "trick of the mind" involving hearing centers in our brain that home in on certain sounds coming from a specific direction.
On the other hand, the Chinese torrent frog actually tunes out frequencies - physically tunes them out to focus on the ultra-sonic sounds emitted by an amphibious mate or the sounds of potential torrent frog intruders poaching in another frog's territory.
Hearing Aids and Background Noise
As the researchers reported humans handle background noise naturally with our advanced auditory processing abilities. When in background noise our brains naturally allow us to focus on the speech (high pitch) we want to hear while tune out the background noise (low pitch). However when someone has hearing loss, this natural ability to block out the background noise is often diminished.
So what is the solution for persons with hearing loss having difficulty hearing in background noise? Hearing aids.
Digital hearing aids have come a long way in reducing the input from background noise for persons with hearing loss. In fact the Torrent frog's hearing system is similar to the noise reduction technologies being used in today's "intelligent" digital hearing aids.
Most digital hearing aids currently on the market offer some level of noise reduction technology that spatially separate sounds, and then processes the sound the way that human brains do. The end result is these intelligent hearing aids boost sound signals of interest, such as desired conversation and reduce the background noise.
Tomorrow's Hearing Aids
The future? You wouldn't think these intelligent hearing aids could get anymore sophisticated but they will.
The average age of wearer of hearing aids continues to be younger and younger. And with that means noisier listening environments and more demanding wearers. With ongoing research and development, hearing aid manufacturers will continue to offer more intelligent and sophisticated hearing aids so humans can continue to hear their love calls or whatever it may be they want to hear.
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