Robotic Sonar System Inspired by Bats

Robotic Sonar System Inspired by Bats

Team at Virginia Tech hopes to create small, efficient sonar systems that use less power than current arrays

WASHINGTON, D.C., May 20, 2015 — Engineers at Virginia Tech have taken the first steps toward building a novel dynamic sonar system inspired by horseshoe bats that could be more efficient and take up less space than current man-made sonar arrays. They are presenting a prototype of their “dynamic biomimetic sonar” at the 169th Meeting of the Acoustical Society of America in Pittsburg, Penn.

Bats use biological sonar, called echolocation, to navigate and hunt, and horseshoe bats are especially skilled at using sounds to sense their environment. “Not all bats are equal when it comes to biosonar,” said Rolf Müller, a mechanical engineer at Virginia Tech. “Horseshoe bats hunt in very dense forests, and they are able to navigate and capture prey without bumping into anything. In general, they are able to cope with difficult sonar sensing environments much better than we currently can.”

To uncover the secrets behind the animal’s abilities, Müller and his team studied the ears and noses of bats in the laboratory. Using the same motion-capture technology used in Hollywood films, the team revealed that the bats rapidly deform their outer ear shapes to filter sounds according to frequency and direction and to suit different sensing tasks.

“They can switch between different ear configurations in only a tenth of a second – three times faster than a person can blink their eyes,” said Philip Caspers, a graduate student in Müller’s lab.

Unlike bat species that employ a less sophisticated sonar system, horseshoe bats emit ultrasound squeaks through their noses rather than their mouths. Using laser-Doppler measurements that detect velocity, the team showed that the noses of horseshoe bats also deform during echolocation–much like a megaphone whose walls are moving as the sound comes out.

The team has now applied the insights they’ve gathered about horseshoe bat echolocation to develop a robotic sonar system. The team’s sonar system incorporates two receiving channels and one emitting channel that are able to replicate some of the key motions in the bat’s ears and nose. For comparison, modern naval sonar arrays can have receivers that measure several meters across and many hundreds of separate receiving elements for detecting incoming signals.

By reducing the number of elements in their prototype, the team hopes to create small, efficient sonar systems that use less power and computing resources than current arrays. “Instead of getting one huge signal and letting a supercomputer churn away at it, we want to focus on getting the right signal,” Müller said.

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ABOUT THE ACOUSTICAL SOCIETY OF AMERICA
The Acoustical Society of America (ASA) is the premier international scientific society in acoustics devoted to the science and technology of sound. Its 7,000 members worldwide represent a broad spectrum of the study of acoustics. ASA publications include The Journal of the Acoustical Society of America (the world’s leading journal on acoustics), JASA Express Letters, Proceedings of Meetings on Acoustics, Acoustics Today magazine, books, and standards on acoustics. The society also holds two major scientific meetings each year. See https://acousticalsociety.org/.

Accents: Hard to Understand, Harder to Remember

Hard to Understand, Harder to Remember

In a study, native English speakers had more difficulty recalling words spoken in an unfamiliar Korean accent, suggesting that the effort listeners put into understanding a foreign accent may lessen their ability to process the information.

WASHINGTON, D.C., May 18, 2015 — Struggling to understand someone else talking can be a taxing mental activity. A wide range of studies have already documented that individuals with hearing loss or who are listening to degraded speech — for example over a bad phone line or in a loud room — have greater difficulty remembering and processing the spoken information than individuals who heard more clearly.

Now researchers at Washington University in St. Louis are investigating the relatively unexplored question of whether listening to accented speech similarly affects the brain’s ability to process and store information. Their preliminary results suggest that foreign-accented speech, even when intelligible, may be slightly more difficult to recall than native speech.

The researchers will present their findings at the 169th meeting of the Acoustical Society of America, held May 18 – 22 in Pittsburgh, Pennsylvania.

Listening to accented speech is different than other more widely studied forms of “effortful listening” — think loud cocktail parties — because the accented speech itself deviates from listener expectations in (often) systematic ways, said Kristin Van Engen, a post-doctoral research associate in the linguistics program at Washington University in St. Louis.

How the brain processes information delivered in an accent has relevance to real-world settings like schools and hospitals. “If you’re working hard to understand a professor or doctor with a foreign accent, are you going to have more difficulty encoding the information you’re learning in memory?” Van Engen asked. The answer is not really known, and the issue has received relatively little attention in either the scientific literature on foreign accent processing or the literature on effortful listening, she said.

To begin to answer her question, Van Engen and her colleagues tested the ability of young-adult native English speakers to store spoken words in their short-term memory. The test subjects listened to lists of English words, voiced either with a standard American accent or with a pronounced, but still intelligible Korean accent. After a short time the lists would randomly stop and the listeners were asked to recall the last three words they had heard.

All the volunteer listeners selected for the study were unfamiliar with a Korean accent.

The listeners’ rate of recall for the most recently heard words was similarly high with both accents, but Van Engen and her team found that volunteers remembered the third word back only about 70 percent of the time when listening to a Korean accent, compared to about 80 percent when listening to a standard American accent.

All of the words spoken with the accent had been previously tested to ensure that they were understandable before they were used in the experiment, Van Engen said. The difference in recall rates might be due to the brain using some of its executive processing regions, which are generally used to focus attention and integrate and store information, to understand words spoken in an unfamiliar accent, Van Engen said.

The results are preliminary, and Van Engen and her team are working to gather data on larger sets of listeners, as well as to test other brain functions that require processing spoken information, such as listening to a short lecture and later recalling and using the concepts discussed. She said work might also be done to explore whether becoming familiar with a foreign accent would lessen the observed difference in memory functions.

Van Engen hopes the results might help shape strategies for both listeners and foreign accented speakers to better communicate and ensure that the information they discussed is remembered. For example, it might help listeners to use standard strategies such as looking at the person speaking and asking for repetition. Accented speakers might be able to improve communication by talking more slowing or working to match their intonation, rhythm and stress patterns more closely to that of native speakers, Van Engen said.

———————– MORE MEETING INFORMATION ———————–
USEFUL LINKS
Main meeting website: https://acousticalsociety.org/asa-meetings/
Press Room: https://acoustics.org/world-wide-press-room/

WORLDWIDE PRESS ROOM
In the coming weeks, ASA’s Worldwide Press Room will be updated with additional tips on dozens of newsworthy stories and with lay language papers, which are 300 to 500 word summaries of presentations written by scientists for a general audience and accompanied by photos, audio and video. You can visit the site during the meeting at https://acoustics.org/world-wide-press-room/.

PRESS REGISTRATION
We will grant free registration to credentialed journalists and professional freelance journalists. If you are a reporter and would like to attend, contact AIP Media Services at media@aip.org. For urgent requests, staff at media@aip.org can also help with setting up interviews and obtaining images, sound clips, or background information.

ABOUT THE ACOUSTICAL SOCIETY OF AMERICA
The Acoustical Society of America (ASA) is the premier international scientific society in acoustics devoted to the science and technology of sound. Its 7,000 members worldwide represent a broad spectrum of the study of acoustics. ASA publications include The Journal of the Acoustical Society of America (the world’s leading journal on acoustics), JASA Express Letters, Proceedings of Meetings on Acoustics, Acoustics Today magazine, books, and standards on acoustics. The society also holds two major scientific meetings each year. See https://acousticalsociety.org/.

On Bleats, in the Year of the Sheep

David G. Browning, 139 Old North Road, Kingston, RI 02881 decibeldb@aol.com

Peter M. Scheifele, Dept. of Communication Science, Univ. of Cincinnati, Cincinnati, OH 45267
Click here to read the abstract

A bleat is usually defined as the cry of a sheep or goat but they are just two voices in a large worldwide animal chorus that we are just starting to understand.

A bleat is a simple short burst of sound comprised of harmonic tones. It is easily voiced by young or small animals, who are the majority of the bleaters. From deer to polar bears; muskoxen to sea lions, the young bleats produce a sound of enough character to allow easy detection and possible identification by concerned mothers. As these animals mature usually their voices shift lower, longer, and louder and a vocabulary of other vocalizations are developed.

But for some notable exceptions this is not the case. For example, sheep and goats retain their bleating structure as their principal vocalization through adulthood – hence bleating is usually associated with them. Their bleats have been the most studied and show a characteristic varietal structure and at least a limited ability for maternal recognition of specific individuals.

For another example, at least four small varieties of toad, such as the Australian Bleating Toad and in America, the Eastern Narrow Mouthed Toad are strong bleaters through their entire life. Bleats provide them a signature signal that carries in the night and is easily repeatable and sustainable. But why these four amphibians? Our lack of an answer speaks to our still limited knowledge of the vast field of animal communication.

Perhaps most interestingly, the Giant Panda retains bleating while developing a complex mix of other vocalizations. It is probably the case that in the visually challenging environment of a dense bamboo thicket they must retain all possible vocal tools to communicate. Researchers link their bleating to male size and female age.

In summary, bleating is an important aspect of youth for many animals; for some it is the principal vocalization for life; and, for a few, a retained tool among many.