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News Release 11-154

Study Reveals How Bats Stay on Target Even in Dark, Cluttered Environment

Insights could lead to the development of more precise sonar-led vehicles

A bat emitting sounds.

A bat emits sounds, and thereby creates orienting echoes.

July 28, 2011

View a video of how sonar enables bats to navigate and hone in on targets in dark, cluttered environments.

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In a paper published in the July 29 issue of Science, James Simmons and Mary Bates of Brown University, along with researchers from the Republic of Georgia, reveal how bats expertly use echolocation to hone in on specific targets, such as prey organisms, without being distracted or set off course by background objects in their environments.

It has long been known that bats emit high frequency sonar blasts, and then construct a three dimensional picture of their environment based on returning echoes.  But the new research, which was partially funded by the National Science Foundation, shows how bats interpret the cacophony of returning echoes to distinguish their priority target from background clutter.

Simmons explains that when a bat chirps, it waits for the corresponding echo; it makes a mental fingerprint of the emitted sound and its echo. If the broadcast/echo fingerprints match up precisely, then the bat "will process it and produce an image," Simmons said. In many cases, that image would be the bat's target object. But when the second harmonic is weaker in the echo fingerprint, the response from the bat's neurons' is delayed by as few as 3 microseconds. That momentary delay, while undetectable to humans, is enough to tell the bat that the object is present, but it is not its primary interest.

"The bat takes clutter and defocuses it, like a camera would, so the target remains highly defined and in focus," Simmons said.

For more information about this research, see the accompanying video and Brown University's press release.


Media Contacts
Richard Lewis, Brown University, (401) 863-3766, email:
Lily Whiteman, National Science Foundation, (703) 292-8310, email:

Program Contacts
Michelle Elekonich, National Science Foundation, (703) 292-7202, email:

Principal Investigators
James Simmons, Brown University, (401) 863 -1542, email:

Mary Bates, Brown University, (401) 258-1850, email:

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2019, its budget is $8.1 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives more than 50,000 competitive proposals for funding and makes about 12,000 new funding awards.

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