Acoustic systems enter homeland security market.

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 applications.

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 deployed.

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 said.

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 Base, N.J.

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.