November 2007, Volume 5, Issue 11

Bats in the News

Studying ‘Bat Talk’

Barbara French, a bat rehabilitator and Bat Conservation International’s Science Officer, listened for years to the sounds of the Mexican free-tailed bats in a small captive colony behind her Austin home. She (along with Amanda Lollar, founder/president of Bat World Sanctuary of Mineral Wells, Texas) was convinced she was hearing much more than just random chirps and buzzes.

“It seemed to us they were using a very complex system of communication,” French told the San Antonio Express-News. “All these sounds were being put together in ways that gave meaning to the content.”
French and scientists with whom she collaborated eventually confirmed those suspicions (see BATS magazine, Fall 2004). Express-News reporter Cindy Tumiel noted that scientists have confirmed bats use an array of sounds, combining them into a basic sort of syntax to communicate within their colonies and to express their individuality.
Mother bats teach unique sounds to their newborns to help in locating their babies in huge nursery colonies. Male bats, the newspaper said, sing like birds, “each one emitting a unique high-pitched bit of bat opera when it is time to attract females for mating.”
Now brain physiologists are exploring “bat talk” in hopes of better understanding the human brain’s circuitry for speech and language. The Express-News said scientists hope their work with bats might eventually lead to such things as better hearing aids or new treatments for stuttering and other human speech disorders.
At the University of Texas at Austin, auditory neurophysiologist George Pollak is trying to understand how the bats process the social communication sounds they hear and how they recognize individual calls.
"What I want to know,” he told Tumiel, “is how they are extracting information from those calls. And when I know that, then I want to know what is the (brain) circuitry underlying the ability to extract information out of those calls. How does the nervous system, with all its millions of neurons, come to represent one call so it can distinguish that call from all other calls?”
Pollak said all mammals process sounds and seem to do much of that processing in very similar ways. “We have the same structures, the same kinds of wiring, the same kinds of processing,” he told the Express-News.
So his laboratory is trying to identify which areas of the brain the bat uses to coordinate sounds and “make sure that one syllable follows another syllable correctly. The results might shed new light on human speech disorders.
The newspaper also reports that German engineers are using some of Pollak’s results to develop tools that filter background noises and recognize voice commands at an assembly plant. Such research could also lead to improved hearing aids.

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