Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Listening to gunshots may save lives and wildlands

17.11.2006
From the crack of a supersonic bullet, Montana State University electrical engineering professor Rob Maher is exploring how sound can be used for everything from saving soldiers from snipers to saving wilderness from noise pollution.

This fall, Maher presented the results of two years of research into gunshots at the Institute of Electrical and Electronic Engineers (IEEE) Signal Processing Society's annual meeting in Jackson Hole, Wyo.

Because of its intense energy and distinctness, a gunshot is "the perfect signal" with which to explore the uses of sound, Maher said.

"It produces what engineers call the 'impulse response' of the sonic environment," Maher said. "If we can't make sense of how a gunshot behaves, then it's unlikely we can do much with more complicated, or lesser quality, sounds."

Maher initially explored two questions with gunshots: First, could the sound of a gunshot on a 911 recording be linked to a specific weapon? The question has intrigued prosecuting attorneys for decades. Second, could the sound of a gunshot be used to determine the location of a hidden sniper?

Through a search of previous studies and his own research, Maher found the "acoustical fingerprinting" of a gunshot from a 911 tape was impossible.

"If you had a very high quality recording made with a very high quality microphone, you might be able to determine if it was a handgun or rifle and the type of ammunition - at best - but you couldn't rule in, or out, a specific firearm," Maher said.

Finding a sniper holds more promise. While a sniper may be able to hide and use a silencer to cover the sound of gunpowder exploding in a shell, the laws of physics will reveal the path of a bullet.

"Most military rifles fire bullets at supersonic speeds," Maher said. "At that speed, the air in front of the bullet doesn't move out of the way in a nice, regular fashion. It moves in a shock."

That shock creates one "boom." There is a second, smaller "boom" as the air returns to normal.

This phenomenon is clearly heard when something big, like a space shuttle, breaks the sound barrier. The shuttle creates two booms as it comes in for landing.

"There is no way to hide the shock wave created by a supersonic bullet," Maher said.

Those booms can be recorded using microphones placed in different locations and then with geometry, the trajectory of the bullet can be determined through triangulation.

Maher successfully determined the trajectory of a bullet using this method at the Logan Shooting Range, near Trident, Mont.

"There are a few commercial systems using this method in Iraq," Maher said. "But they're classified and it's not clear what's being done."

The only way a sniper could hide from such shockwave detection is to fire a bullet that travels at less than the speed of sound, an unlikely prospect since the world's most common weapon, the AK-47 rifle, fires bullets at a little more than twice the speed of sound.

While Maher was able to determine the trajectory of a bullet on a flat shooting range, the real-world application in a city, where sound would bounce off buildings or be absorbed by trees is far more difficult and it plays into another research area: using technology to pick a desired sound from background noise.

"For humans, picking out a desired sound from reflections or background is very easy: A parent can pick out their child's cry in a noisy nursery," Maher said. "But creating technology that could mimic this is very difficult."

Technology that could sort desired sounds from background noise could be used to monitor wildlife habitats. Microphones could record a month's worth of sound in an area and then computer software would sort that massive amount of data into useable chunks: elk bugles, aircraft noise, wolf howls, gunshots, etc.

"Take frogs for example," Maher said. "Frogs are very sensitive to environmental changes. You might be able to augment temperature, moisture and other environmental data with 24/7 recordings of frog vocalizations to estimate population trends.

"You might learn all sorts of interesting things: such as there is less frog noise year-to-year, or maybe the frogs croak at different times year-to-year based on other environmental factors."

But to hear the frogs, Maher will have to spend some more time listening to gunshots.

"The next step is to do more careful calibrations on all the parameters: the gunpowder, the local geometry, the acoustical characteristics of the vicinity and then work from there," he said.

It has been an interesting project for Maher, not only because it involves acoustics - one of his specialties - but also because he came into the project knowing almost nothing about guns.

"I'm not a hunter," he said. "But fortunately in Montana I've had no trouble finding lots of knowledgeable help."

Contact: Rob Maher, (406) 994-7759 or rmaher@ece.montana.edu.

Rob Maher | EurekAlert!
Further information:
http://www.montana.edu

More articles from Ecology, The Environment and Conservation:

nachricht Bioinvasion on the rise
15.02.2017 | Universität Konstanz

nachricht Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

From rocks in Colorado, evidence of a 'chaotic solar system'

23.02.2017 | Physics and Astronomy

'Quartz' crystals at the Earth's core power its magnetic field

23.02.2017 | Earth Sciences

Antimicrobial substances identified in Komodo dragon blood

23.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>