Acoustic-energy weapons have intrigued military scientists ever
since the Germans boasted about them during World War II. But after
decades of research, such weapons have yet to be fielded.
The Joint Non-Lethal Weapons Directorate stopped funding acoustic-energy
research, a program it has inherited from the Army. Nevertheless,
there is some ongoing work on acoustic weapons at the Army’s
Picatinny arsenal, in New Jersey. A company named American Technology
Corporation (ATC), based in San Diego, currently is working with
scientists from the arsenal on a new type of acoustic weapon.
ATC has been developing the directed stick radiator, a weapon that
fires high-intensity sonic bullets, said the company’s chairman
Elwood Norris. The device could be used to inflict pain and disorient.
The directed stick radiator is encased in a polymer composite tube
about one meter long and four centimeters in diameter. The company
acquired the patent from a German scientist.
The weapon is directional, explained Norris, and is only effective
at distances of no more than 15 feet. “It works in the range
of hearing and it is so intense that it is painful,” said
Norris. However, “for crowd-control [this weapon] wouldn’t
be enough,” because it wouldn’t cover a large enough
The directed stick radiator is light-weight, battery-powered and
could be clipped to an M-16 rifle.
According to Kevin Stul, an engineer at the Non-Lethal Weapons
Directorate, any sound between 125-150 decibels is considered effective.
“It is difficult to reach that level of acoustics beyond several
meters,” he said.
“There is not a repeatable universal bio effect that we can
take advantage of with acoustics,” said Stul. This is one
of the main reasons why his office dropped the program. “We
set up an executive criteria for the Army to demonstrate that you
can achieve a repeatable bio-effect in an animal,” Stul told
“You’d expose a surrogate to whatever frequencies of
acoustic energy and that animal would display some sort of adverse
effect and that would be a repeatable event if you exposed any animal
to that set of frequency.”
But the Army could not demonstrate that effect, he said. “Even
if you are able to achieve incapacitation, it is very difficult
to propagate acoustic energy.”
“The responses are not universal,” said John Kenny
an acoustics engineer at the Applied Research Lab at Penn State
University. “Most non-lethal weapons rely on pain to get people
to comply.” Kenny said the use of acoustic weapons was based
on the same idea of inflicting pain.
“Pain aversion is related to [people’s] motivation,”
Kenny said. “You are in Washington and you are in some kind
of demonstration and the police asks you to disperse—you get
out of there. But if you are in Palestine and if they had bombed
your house already, killed your family there isn’t any non-lethal
weapon that is going to stop you.”
David Swanson works at the advanced sensors and control department
of the laboratory. “Sound in the air is essentially harmless
physically,” he said. But short bursts of sounds can cause
some damage. “Very high amplitude sounds with sharp pressure
rises can tear cell structures and damage nerves,” he said
during a presentation at Quantico, Va. “Damage to the cochlea
and auditory nerve sensor cells are considered permanent, while
the middle and outer ear can be surgically repaired.”
The severe ringing which accompanies deafness can sometimes lead
to insanity, Swanson said. In Third World countries, where illiteracy
is fairly high, the loss of hearing could be a worse handicap than
amputation. In the United States and other NATO countries, hearing
aids and hearing loss disability are the most costly health claims,
said Swanson. Ultimately, if hearing loss occurs, an acoustic non-lethal
weapon is no longer effective. For a non-lethal acoustic weapon
to be effective it must be disruptive to the neural pathways to
the brain, said Swanson. Also, it must not cause any hearing loss.
According to Swanson, acoustic energy weapons would be effective
in water. “The sound that passes through water can destroy
cells,” he said. “You can be seriously injured or killed,
depending on the frequency and range.” However, they can stay
non-lethal at a certain range.
Air Force Major Noel Montgomery, chief of health effects assessment
at the Non-Lethal Directorate, explained that there are two types
of acoustics: audible—such as flash bangs and loud music—and
a field called infrasound.
Infrasound is too low in frequency to be heard by human ears. Montgomery
explained that anything below 20 hz is considered infrasound. But
that effort was discontinued, because the military users wanted
a quieter, stealthy weapon, he said.
Infrasound in the air, additionally, does not couple well with
the human body. “It just bounces off,” he said. “In
order for it to cause an effect you have to have a huge amount.
... We could not generate as much.” The effect of powerful
infrasound would be pain, resonance in the body organs and even
liquefaction of the bowels, said Montgomery. But he added that only
10 percent of the people exposed to infrasound get nauseous.
Operator safety is a critical consideration, said Stul. The people
using the weapons could have been just as adversely affected as
the people targeted. He pointed out that special application of
acoustics cannot be ruled out. For example, it could be used for
security applications, in combination with other weapons.
A multi-sensory grenade is being developed under a Marine Corps
contract at Science and Research Associates in San Diego. “They
have been playing with all sorts of different irritants,”
said Stul. The grenade would combine audible sound, flaring light
A SARA official refused to comment on the development, citing company
policy and government confidentiality. Jim Wes, a business development
executive at the company, said that acoustic weapons and other sorts
of non-lethal weapons will not necessarily defeat an attacker, but
are useful tools to assess the intentions of potential criminals.
Meanwhile, General Dynamics Bath Iron Works, in Bath, Maine, is
developing an acoustic-energy weapon that potentially could have
applications in ship self-defense, said Vince Quintana, a company
During the Surface Navy Association Symposium, in Arlington, Va.,
Quintana told National Defense that the Navy is considering testing
this technology as an alternative means of defending a ship when
the commander may not want to fire lethal rounds against an approaching
The acoustic energy weapon, if it works, could disable a suspected
enemy ship’s crew. However, Quintana cautioned that the technology
is not fully mature.
The system in development at Bath Iron Works would be based on
commercial technologies. The hardware includes a high-end, medium-range
wireless communications system, wearable computers for the ship
sentries, a notebook computer for the commander in charge of the
ship and up to five acoustic projectors that would be installed
around the ship.
These types of non-lethal weapons, said Quintana, would give ship
commanders flexibility to deal with potential aggressors “without
getting mired in the seriousness of consequences” associated
with the use of lethal fire.