High-Intensity Acoustic Devices as Weapons: A look at the Legalities

lrad use legal
Hearing Health & Technology Matters
November 28, 2022

By Fred Cohen

It began innocently enough. A Pittsburgh newspaper announces a settlement with a professor who suffered hearing loss in September 2009 during the Group of 20 economic summit. The professor was in Pittsburgh studying the possible impact of protests on monetary policy and was about 100 feet away from a Long Range Acoustic Device (LRAD) when it was deployed to disperse protesters. She apparently was not wearing her Bose headphones–so there may be a lesson here for protesters.

Exploring the subject further, I learned that in November 2005, Somali pirates attacked a cruise ship armed with an LRAD that was defensively beamed at the pirates. The noise attack reportedly drove them away, but we don’t know if the directed 162-decibel (dB) sound blast (130 dB is the pain threshold) caused them lasting impairment.

Needless to say, no settlement is anticipated in this case. As for pirates who now ply their trade wearing headphones, I have no comment.

The LRAD device is described as having been designed primarily to “hail, warn, and notify” vehicles and sea vessels at a distance. It was further developed to assist our military in manning checkpoints in hostile territory where the intention of the occupants of an oncoming vehicle may be unclear. It allows voice commands and warnings to be sent beyond the range of small arms. The device’s small size allows for mounting on a variety of platforms from guard towers to tripods, cars, ships, and trucks.

American Technology Corp., which manufactures the LRAD, describes it as a “highly directional, warning and deterrent system” that “uses high…intensity focused acoustic output to communicate over distance with authority and high intelligibility.” See Major Joe Schrantz’s article, “The Long Range Acoustic Device: Don’t Call it a Weapon; Them’s Fightin’ Words” in the August 2010 Army Law, pages 53-59.

Schrantz also coyly points out that an LRAD is not a weapon if it’s used for its intended purpose as a communication device. I might add that the same is true of a baseball bat unless it is used with force on your skull.

Was the Pittsburgh settlement, then, based on a crowd-control purpose gone wrong or was the focused noise outpoint intended as a use of force to disperse the crowd: Stay on the pavement v. leave now?

If the LRAD was, or is, used as the acoustic equivalent of a police officer’s baton, when may force of that magnitude be lawfully used?


Those aforementioned Somali pirates cannot turn to the protective armor of the First Amendment to protest LRADs being shot at their ears. If intended victims may use deadly force to ward off a potentially lethal attack (e.g., armed kidnapping for ransom), then a jolt from an LRAD is surely permissible.

The interesting question regarding the use of acoustic force is precisely when and how the right to defend oneself or others applies. Once force commensurate with the threatened or applied force has been used effectively and, e.g., the pirates are fleeing, the intended victim cannot continue to use force that is intended to or likely to kill or inflict serious harm on his routed attackers. To shoot at a fleeing felon is not self-defense. Rather, it is an action intended to punish or capture a wrongdoer who has been successfully rebuffed.

Self-defense is a universally recognized defense in criminal law. It allows one who is attacked to use force commensurate with the initial force to repel the attacker. A victim who is punched in the face cannot respond with a .45 to the head; but he may, of course, fight back.

Is an acoustic blast that is used to ward off an attack likely to be viewed as a deadly weapon and thus subject to highly restrictive rules as a use of force? I don’t think so. These acoustic devices are part of a surprisingly broad arsenal of directed-energy, non-lethal weapons: These include a beam of concentrated electromagnetic energy or atomic/subatomic particles, chemical lasers, diode lasers, and high-power microwaves.

Some lasers induce psychological and behavioral changes in the target.  There is also a laser-induced plasma that causes pain and temporary paralysis by stimulating the target’s skin.

One advantage of an LRAD is that its targets will reflexively cover their ears at a certain noise level and thus drop any weapons (or signs) they may be carrying.

The day may come when we would prefer just being shot with a good ole bullet, although I suppose it would depend where. Annoying music was blasted at David Koresh and the Branch Davidians prior to the now infamous fatal attack by government agents.

American interrogators in Iraq, Afghanistan, and Guantanamo Bay have regularly used loud music to get suspects to talk without use of physical force. Some of the favorite songs for this purpose are Bruce Springsteen’s Born in the USADirrty by Christina Aguilera; These Boots Were Made for Walking by Nancy Sinatra; Hells Bells by AC/DC; and–this may be going way too far–anything by Barry Manilow and Barney the Dinosaur’s I Love You.

When the content of music is mixed with volume even on an ordinary music-transmitting device, the impact can be extraordinary in a tightly controlled physical space. However, an LRAD is qualitatively different from any music-transmitting device, and therefore is placed in a separate category, that of a sound-transmitting device.

When used as a weapon, say to repel an attack or disperse a mob, an LRAD is subject to all the legal rules governing the use of force. For the user to be charged with a crime, knowledge of the device’s potential for causing permanent hearing loss must be ascribed to the person.

When the LRAD is used as a crowd-control device or in its original early warning mode, the legal issues are far different. Any loss of hearing, I would imagine, would be due to the user’s negligently setting the volume too high. That could still result in civil recovery of damages, but a criminal charge would be unlikely.

Fred Cohen, LLB, LLM, Yale Law School, has taught at a number of leading law schools. He was a founder of the Graduate School of Criminal Justice at the State University of New York at Albany. He now serves as the federal court-appointed Monitor in Fussell v. Wilkinson, which encompasses medical and dental care in Ohio’s prisons. He is author of The Mentally Disordered Inmate and the Law and is the editor of Correctional Mental Health Report and Correctional Law Reporter. He is a frequent contributor to Hearing Views.

**this piece has been updated for clarity. It originally published on November 28, 2012

  1. Interesting discussion… I see no problems using this in a combat/threat type of situation when necessary, but it’s another issue completely if it is being used to inflict permanent hearing loss on demonstrators that are peaceful.

    If demonstrators are becoming violent and no other good options are suitable, then law enforcement should have the capacity to use this technology without recourse, if necessary.

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