REVERSING TIME TO CATCH SNIPERS.

[MGKrebs]

From the regular physics news update.

I wonder if they can use this for the JFK thing? Did they get enough audio sources?


PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics News
Number 687 June 4, 2004 by Phillip F. Schewe, Ben Stein

REVERSING TIME TO CATCH SNIPERS. At last week's 75th anniversary
meeting of the Acoustical Society of America in New York City,
researchers presented a system that uses "time-reversed" acoustics
to pinpoint the exact locations of gunfire and explosions in an
urban environment. Coming from the U.S. Army's Cold Regions
Research and Engineering Laboratory and the University of
Connecticut, the researchers ([e-mail]
and [e-mail]) tested the system in a small
"training" village consisting mainly of two-story concrete-block
buildings. In their tests, they fired a gun at an arbitrary location
within the village. The gunshot echoed from building walls and
other surfaces. A network of simple audio sensors recorded the
reverberations at unique vantage points. The researchers then
turned to a computer, which contained a 2-D computer model of the
village. Inside this "virtual village," the computer generated a
backwards version of each recorded sound wave. Displaying a map of
the village, the computer broadcasted the time-reversed waves from
the locations corresponding to the sensors that recorded the
original waves. In the computer map of the village, the
time-reversed waves eventually returned and converged at the spot
corresponding to the source of the gunshot. The researchers are
hoping to develop the system for real-world use, for example by
reducing the amount of computer processing time associated with the
procedure so that it can potentially pinpoint snipers and explosions
in real-time. (Paper 5aPAb5; pictures, movies and lay-language text
at http://www.acoustics.org/press/147th/liu-albert.html)

[lutherj]

1. The Church Committee did use this technology with an audio recording

produced by a radio that a motorcycle cop left transmitting during the assassination. It was discovered that there was a 4th shot on the tape that was only detectable by computer analysis, and that it most likely came from the area of the grassy knole. The tape analysis was brought into question by subsequent investigators. However, it was cooborated by a British team about a year ago.

[benburch]

2. Sadly...

The JFK audio they have is uncertain; It is uncertain whether what was recorded by an open police mic is a gunshot or not. It is uncertain which mic recorded the possible gunshot noises. And I believe that only one recording exists from one location.