The use of amplifiers in homeland defense is going far beyond the
simple bullhorns and bugle-shaped speakers mounted on towers. From
public address systems to directed warnings to trespassers, the
science of sound is being developed and marketed for homeland security
American Technology Corp., of Topsham, Md., makes systems that can
direct tightly focused acoustic beams at specific targets. Its Long
Range Acoustic Device can project intelligible voice communication
as far away as 500 meters.
The unit uses the same concept as other phased array systems, aiming
many small sound waves to converge into a single beam. The beam
neatly projects away from the flat, 33-inch diameter speaker, with
few or none of the wavelets audible to the users.
LRAD is currently used on Navy ships, an application developed
in response to the small boat terrorist attack on the USS Cole.
“If you can’t talk to them, you can’t determine
intent, and you have to put a boat in the water,” said A.J.
Ballard, director of force protection systems at ATC.
LRAD is also used by the military in Iraq and Afghanistan, providing
a communication system for vehicles approaching checkpoints. Ballard
noted that his system was being shipped to the Army 3rd Infantry
Division to be used at checkpoints when soldiers accidentally shot
and killed an Italian intelligence agent escorting an alleged hostage
from Iraq. “LRAD was still on its way over,” he said.
“If you read the reports, they say those soldiers were screaming
at the car, trying to be heard.” The 3rd ID now has 150 LRADs
In late April, ATC reported a $690,000 order from the Army 3rd
Armored Cavalry Regiment.
The system has attracted customers beyond the military. LRAD is
employed by large cruise ships, including the Queen Mary and all
Princess cruise liners, to chase off harmless boaters and determine
the intent of others breaching minimum standoff distances, Ballard
Border control officers also field speakers, as did the New York
Police Department during the Republican National Convention. ATC
personnel are quick to point out that their systems have been designed
beneath pain thresholds, and are not non-lethal weapons.
Domestic use is the next hot market, officials said. In June, ATC
unveiled a system optimized for homeland security operations, roughly
half the size and weight of LRAD.
The Medium Range Acoustic Detector has less range, but its portability
and ability to be mounted on various platforms opens the system
to police boats, helicopters, border patrol vehicles and infrastructure
security perimeters. “We’re just now getting into municipalities,”
said Kenneth Winter, ATC’s director of systems engineering.
By incorporating a video camera in a remotely controlled, pan-tilt
speaker, harmless intruders can be chased off without resorting
to deploying a security guard. Flashlights and laser “dazzlers”
can also be mounted.
Public address systems are moving beyond whooping tornado alarms.
Acoustic Technology Inc., of Boston, is developing wireless emergency
warning systems that can be controlled by mouse click at either
central or mobile control stations. ATI has configured public address
systems for the naval base at Groton, Conn., and McGuire Air Force
The move to wireless is critical, as warning systems must work
independent of cables or monitoring facilities that could be destroyed
in a fire or explosion. ATI also makes solar-powered systems.
With the correct software, automated announcements can be integrated.
Rather than simple tones, recorded instructions can be given. When
a public address alert is triggered, a host of automatic contact
mobile phone and pager numbers can be dialed.
The company also offers modeling programs to help customers configure
tower arrays to reach the entire area in need of coverage. This
is vital for complying with government safety regulations at places
with sensitive infrastructure, as well as for communities with homeland
security or natural disaster concerns.