Sound is among the oldest tools humans have used against one another. Armies have long used drums, horns, bells, war cries and other sounds to amplify their apparent strength, frighten opponents, coordinate movements and create uncertainty. What changed in the modern era was not the discovery that sound could influence people, but the ability to measure, reproduce, direct and weaponize it with increasing precision.
By the twentieth century, acoustics had entered nearly every layer of military operations. Microphones could locate enemy artillery; sonar could detect submarines; acoustic signatures could guide torpedoes; recorded battlefield noise could create the illusion of nonexistent armies; prerecorded voices could exploit cultural fears surrounding death; and directional loudspeakers could issue commands over distances where ordinary speech was useless. Today, commercial and military systems such as Genasys LRAD and Ultra Electronics HyperSpike can project highly intelligible voice or warning tones over long distances, while naval forces continue to employ sophisticated acoustic sensors, weapons and decoys in submarine warfare.
The history is therefore more interesting than the popular image of a single “sonic cannon.” Acoustic technology has developed along several distinct paths: psychological influence, deception, detection, targeting, countermeasures, communication, deterrence and, at the limits, physical harm.
Sound before the sonic weapon
Ancient armies understood the psychological power of organized noise. The purpose was generally not to injure the enemy with acoustic energy but to alter his perception of the battlefield. At the Battle of Carrhae in 53 BCE, for example, Plutarch described the Parthians’ use of large drums and metallic components to produce an alarming sound before their cavalry attack. The effect was part of a broader effort to frighten and disorient Roman troops (Plutarch, trans. 1914).
That principle survived into industrial warfare. The German Junkers Ju 87 Stuka was equipped on some aircraft with mechanically driven sirens popularly known as the “Jericho Trumpets.” The noise was principally a psychological adjunct to the dive-bombing attack: the approaching sound itself became part of the terror of the weapon (Porges, 2023).
These examples are best described as acoustic psychological warfare, not modern acoustic weapons. The distinction becomes important later. Sound can influence behavior without possessing sufficient physical energy to injure a person.
World War I: hearing the enemy artillery
The First World War transformed sound into a military sensor.
Artillery frequently operated beyond direct visual observation. Smoke, darkness, terrain and defensive fortifications made it difficult to identify the firing position of enemy guns. The answer was sound ranging: arrays of microphones listened for the acoustic wave produced when artillery pieces fired, and the timing differences between microphones were used to calculate the gun’s location.
British physicist William Lawrence Bragg played a major role in developing operational sound-ranging methods. The microphones and recording systems were refined so that the acoustic signature of artillery could be isolated from background noise, while the U.S. Army subsequently employed Sound Ranging Sections with microphone bases and central stations on the Western Front (Van der Kloot, 2005; Tagg, 2017).
This was a crucial conceptual shift: sound no longer merely announced the battle; sound disclosed the hidden enemy.
A weapon did not have to emit the destructive sound. The sound of the enemy’s weapon became intelligence that could be converted into counter-battery fire.
World War II: sonar turns sound into a weapon system
The undersea environment made acoustics even more important. Light disappears rapidly underwater, while sound travels comparatively far. This made sonar central to submarine warfare.
Active sonar transmits an acoustic signal and analyzes returning echoes; passive sonar listens for sounds generated by ships, submarines and machinery. In operational terms, sonar became an underwater analogue to radar, although the two technologies use fundamentally different physical phenomena: radar uses electromagnetic radiation; sonar uses acoustic waves (Naval History and Heritage Command, n.d.).
The real weaponization of underwater acoustics came with acoustic-homing torpedoes.
The U.S. Mark 24 “Fido” was an air-dropped passive acoustic-homing antisubmarine torpedo introduced in 1943. It listened for the acoustic signature of a submarine and homed toward the source. The U.S. Navy’s historical material also records the German Falke acoustic torpedo and the Allied development of acoustic countermeasures such as Foxer noisemakers (Naval History and Heritage Command, 2018).
The significance was profound. A submarine did not have to be seen. It could be heard, classified and attacked because of its acoustic signature.
Modern systems continue this lineage. The U.S. Navy’s Mark 48 heavyweight torpedo is an acoustic-homing weapon equipped with sonar and digital guidance and control systems. The Navy identifies Lockheed Martin and SAIC among contractors associated with the system (U.S. Navy, 2023).
The Royal Navy’s Spearfish likewise incorporates sonar, wire guidance and acoustic sensing within its guidance system; its modernized configuration uses advanced electronics and fibre-optic technology (Royal Navy, 2021).
In this sense, one of the earliest highly successful acoustic weapons was not a sonic cannon at all. It was a conventional explosive weapon whose ability to find its target depended on sound.
Acoustic sensing was not confined to torpedoes. The U.S. Navy also fielded acoustic mines, including the Mark 25 and Mark 26, which could respond to the low-frequency sound generated by passing vessels. (Naval History and Heritage Command, n.d.).
Acoustic deception: the Ghost Army
World War II also produced a very different use of sound.
The U.S. Army’s 23rd Headquarters Special Troops, known as the Ghost Army, was created to deceive German forces about the strength and location of American units. Its 3132nd Signal Service Company developed a specialized “sonic deception” capability, using large loudspeakers and recordings of troop movements, vehicles and construction activity to simulate formations that did not exist (U.S. Army, 2020, 2021).
The technical challenge was considerable. The recordings had to be convincing enough that the enemy could not easily distinguish the artificial sounds from real battlefield activity. Bell Laboratories personnel helped develop the recording technology used in the program (U.S. Army, 2020).
This was sonic deception rather than sonic injury.
The intended target was the enemy’s mental model of the battlefield. A commander who heard heavy vehicles and construction activity behind a line might alter his deployment even if no such force existed.
Acoustics had become a means of manufacturing false military reality.
Vietnam: when the dead spoke
The Vietnam War pushed acoustic PSYOP into a more culturally specific and psychologically unsettling domain.
Under Operation Wandering Soul, U.S. PSYOP personnel used recordings designed to exploit beliefs surrounding death, burial and the fate of spirits. A documented June 24, 1968 instruction sheet associated with the 6th Psychological Operations Battalion identifies tape 059-6T, lists the Viet Cong and North Vietnamese Army as targets, and directs that the tape be played at night (Friedman, n.d.).
The recording combined funeral music, crying and wailing, children’s voices, and voices representing the dead and their relatives. In the reconstructed description, children call for their father and a purported dead father responds. The point was to create the impression that the dead were speaking to the living (Friedman, n.d.).
The technique exploited the psychological significance of death, burial and the possibility of dying away from one’s ancestral home. The objective was not simply to create noise. It was to make the listener attach a culturally loaded meaning to the sound.
This became popularly known as the “Ghost Tape” or “Ghost Tape No. 10.” From a source-critical perspective, however, the documented military designation 059-6T and the Wandering Soul name are more useful than later popular terminology.
Later veteran accounts describe the use of additional environmental sounds, including recorded tiger noises, to reinforce the sense of danger at night. Such accounts are evidence of acoustic experimentation, but dramatic claims concerning exactly how many enemy personnel surrendered as a result remain anecdotal rather than independently established (Friedman, n.d.).
Panama: the loudspeaker as a tactical instrument
During Operation JUST CAUSE in Panama, beginning on December 20, 1989, U.S. PSYOP forces employed tactical loudspeakers, prerecorded material, radio, television, music and improvised broadcasts.
The Army’s historical account identifies prerecorded television, radio and loudspeaker tapes; radio and loudspeaker scripts; and music among the materials prepared for the operation. Operators also used live speech through tactical loudspeakers to communicate with people inside buildings and persuade civilians to leave before troops entered. (Tracy, 2021).
The Panamanian campaign demonstrates the operational importance of live human speech. Although Spanish-language surrender tapes were prepared because of shortages of Spanish-speaking PSYOP personnel, several operators later recalled that they did not use the supplied tapes and instead relied on live or improvised communication. (Tracy, 2021).
Radio was equally important. PSYOP personnel supported round-the-clock broadcasting through Radio Liberty and VOLANT SOLO, producing news, scripts, music and other information products. Soldiers rapidly shifted from prefabricated material to “on the spot” broadcasts and original products when circumstances demanded it. (Tracy, 2021).
The most famous episode took place at the Papal Nunciature, where Manuel Noriega had taken refuge. U.S. forces created a continuous “sound barrier” using music from cassette tapes and local radio through 450-watt loudspeakers mounted on HMMWVs. According to the Army’s historical account, the primary operational purpose was preventing journalists from overhearing negotiations; psychological harassment of Noriega was described as an ancillary benefit. (Tracy, 2021).
This distinction corrects a common popular retelling. Panama was not documented as a repeat of Vietnam’s Ghost Tape operation. The authoritative Army record does not establish the use of supernatural voices, random “human chatter,” or disembodied recordings during JUST CAUSE. Its documented acoustic repertoire is instead one of persuasion, information, music, live communication, broadcasting and localized acoustic masking.
The post-Cold War shift: from loudspeaker to directional acoustic device
The next major development was technological rather than psychological.
The modern Long Range Acoustic Device (LRAD) emerged in the early 2000s from technology developed by American Technology Corporation (ATC). Company filings state that ATC developed the LRAD1000 in 2002, in the aftermath of the USS Cole attack and alongside U.S. Navy requirements for protecting vessels and security zones. The company marketed LRAD as a directional system for hailing, warning and notification rather than simply as a very loud conventional loudspeaker (American Technology Corporation, 2004, 2005).
The technology depended on a fundamental acoustic property: directionality. Instead of distributing sound broadly, an array of transducers concentrates acoustic energy into a relatively narrow beam. This makes it possible to communicate intelligibly over substantial distances in high background noise.
The corporate lineage is itself significant. American Technology Corporation’s acoustic business later became LRAD Corporation, which rebranded as Genasys Inc. in 2019. The LRAD brand remained the company’s principal acoustic-hailing product family (LRAD Corporation, 2019).
Actual modern systems: Genasys LRAD
Genasys currently markets multiple LRAD systems for defense, law enforcement, maritime security, emergency communications and other applications. Its LRAD 450XL-RT, for example, is specified by the manufacturer at a maximum peak output of 150 dB SPL at one metre, a continuous output of 145 dB SPL at one metre, and a maximum stated range of approximately 1,700 metres under specified conditions. These are manufacturer specifications, not independent laboratory measurements (Genasys Inc., 2025).
The systems can be mounted on vehicles, vessels and other platforms, and Genasys markets LRAD technology for defense and PSYOP applications, including the simulation of battle and munitions sounds.
This is where the popular term “sonic cannon” becomes misleading. An LRAD is fundamentally a directional acoustic hailing and warning system. The same hardware can deliver ordinary spoken instructions or prerecorded messages, or generate highly attention-getting warning tones. Its operational importance lies in creating distance, time and an intermediate escalation option before resorting to firearms.
HyperSpike: another real manufacturer
A second major commercial family is HyperSpike, manufactured by Ultra Electronics.
The HS-18 Acoustic Hailing Device is specified by the manufacturer at 156 dB peak acoustic output, a narrow beam of approximately ±5°, a frequency range of 245 Hz–10 kHz optimized for human voice, and a claimed range of up to 3,000 metres. The system supports live microphone input, recording and playback, remote control and integration with cameras or other sensors (Ultra Electronics HyperSpike, n.d.).
These figures should likewise be understood as manufacturer specifications, rather than universal real-world performance.
Its applications include military security, maritime and port security, law enforcement, perimeter protection, airports, commercial shipping and cruise lines. Thus, the technology has migrated well outside traditional warfare.
Civilian security: piracy, ships and emergencies
The maritime environment proved especially suitable for acoustic hailing.
In May 2009, the U.S. Navy’s USNS Lewis and Clark used a long-range acoustic device to issue verbal warnings to suspected pirate skiffs off Somalia after they approached to approximately one nautical mile. The skiffs subsequently abandoned the pursuit (Naval History and Heritage Command, n.d.).
The significance is operational rather than cinematic. The acoustic system allows a ship to warn and identify before the situation reaches the point at which lethal force must be considered.
The U.S. Navy has likewise demonstrated LRADs on unmanned surface vessels, with acoustic hailing integrated with other sensing systems and used to maintain separation from potentially hostile craft (Office of Naval Research, 2008).
The technology is also used in commercial maritime security and emergency communication. Genasys markets LRAD systems for commercial vessels and other maritime applications, including piracy deterrence and long-range warning.
Police and civil unrest
Once acoustic hailing devices entered law enforcement, the distinction between communication equipment and weapon became contested.
LRAD systems have been used to give commands to crowds and issue warnings, but the same platforms can produce intense deterrent tones. The Congressional Research Service describes LRADs as specialized loudspeakers used by law enforcement principally for warnings and instructions to crowds, while also identifying concerns about hearing damage and unsupported or overstated incapacitation claims (Congressional Research Service, 2025).
Human-rights guidance is more explicit. The United Nations recognizes that high-intensity acoustic devices can cause pain, loss of balance, eardrum injury and hearing loss, depending on exposure conditions, and recommends controls on sound level, duration and minimum range (United Nations Office of the High Commissioner for Human Rights, 2024).
There are also documented legal controversies concerning police LRAD use. In Eaton v. Estabrook (2025), the U.S. Court of Appeals for the Second Circuit addressed litigation concerning LRAD deployment against protesters and allegations of physical injury.
Thus, acoustic technology occupies an unusual legal space: a device marketed as a communication system can become a force instrument depending on what signal is transmitted, at what level, for how long, and against whom.
The civilian “Mosquito”
Not every acoustic deterrent is intended for police or military use.
In 2005, Welsh inventor Howard Stapleton developed the Mosquito, marketed by Compound Security Systems Ltd. as a device for discouraging teenagers from loitering around shops and other premises. The system exploited the fact that sensitivity to high-frequency sound generally declines with age.
A 2012 report by York City Council described a later Mosquito version with a setting of approximately 17.4 kHz and a manufacturer-stated maximum output of approximately 108 dB (City of York Council, 2012).
This is an important example because the objective is not to cause physical incapacitation. It is selective discomfort based on age-related differences in high-frequency hearing.
The device illustrates a larger principle of acoustic technology: the “weapon” can be designed around the characteristics of the listener, not simply the volume of the emitter.
Ultrasound: real physics, extraordinary claims
Ultrasound is often pulled into discussions of sonic weapons, but terminology generates confusion.
Ultrasound is simply acoustic energy above the conventional range of human hearing. It is still mechanical acoustic energy. It is not radar, radio or microwave energy.
There is nevertheless a genuine connection between ultrasound and highly directional sound. American Technology Corporation developed HyperSonic Sound (HSS) technology based on parametric acoustic arrays, using ultrasonic frequencies as part of the sound-generation process. Company filings describe a highly directional beam in which nonlinear interaction produces audible sound (American Technology Corporation, 2004).
Such systems are real engineering technologies, but their existence does not establish the popular idea of an invisible ultrasonic weapon that can silently incapacitate people at great distances.
The scientific literature is considerably more conservative.
Jürgen Altmann’s major assessment of acoustic weapons concluded that claims about dramatic infrasound effects had frequently been exaggerated. At sufficiently high intensities, sound can cause pain, equilibrium disturbances and hearing injury; however, generating and propagating the necessary acoustic energy over large useful distances creates severe practical constraints (Altmann, 2001).
Jauchem and Cook (2007), writing from the U.S. Air Force research community, similarly concluded that claimed non-lethal acoustic weapon effects had been substantially overstated and that high-intensity infrasound suitable for practical large-scale application faced basic physical limitations.
The important point is that sound can unquestionably damage hearing, but that fact does not validate every claim made about sonic weapons.
“Acoustic radar” is usually sonar
Another recurring source of confusion is the tendency to describe combined acoustic and electromagnetic sensing as “acoustic radar.”
Radar and sonar share an operational logic: transmit or receive a signal, measure a return or signature, and infer the location and characteristics of a target. But physically they are different.
A radar system transmits electromagnetic waves. A sonar system transmits or receives sound waves.
Modern warfare often combines them. A naval platform may use radar to identify the surface environment while passive and active sonar characterize underwater contacts. A ship can also combine radar, cameras, acoustic detection and a directional loudspeaker to create a layered security system. Historical ATC material describes LRAD configurations capable of integration with radar and cameras, allowing remote operators to assess and communicate with a threat.
The future of military acoustics is therefore not necessarily “ultrasound versus radar.” It is increasingly sensor fusion, in which acoustic, optical, infrared, electromagnetic and other information sources are combined.
Acoustic warfare beneath the surface
The most mature and strategically important form of contemporary acoustic warfare remains underwater.
A submarine’s survival can depend on controlling its acoustic signature. Ships and submarines therefore use acoustic countermeasures designed to confuse the sensors and guidance systems of enemy weapons.
The U.S. Navy’s AN/SLQ-25 NIXIE is a classic example. It is an externally towed acoustic countermeasure designed to create a false or more attractive target for an incoming acoustic-homing torpedo. Navy documentation describes NIXIE as a sound-producing decoy intended to affect the acoustic environment around the protected ship (U.S. Navy, 2009).
Modern systems continue this lineage. Navy programs include the AN/SLQ-25E and other acoustic countermeasures designed to defeat torpedoes and acoustic sensors. NAVSEA’s torpedo-defense work has also included the AN/SLQ-61 Lightweight Tow, an underwater acoustic projector intended to counter several classes of torpedo threat (NAVSEA, 2018).
Modern naval acoustic warfare is therefore a contest of hearing and deception:
Can you hear the other submarine?
Can you distinguish it from background noise?
Can you prevent the other side from hearing you?
Can you make your decoy sound more convincing than the real target?
Those are acoustic-weapons questions even when no one is deliberately “blasting” a human being with sound.
The myth of the Nazi “sound cannon”
Popular histories frequently repeat a story about a German World War II “sound cannon” that supposedly used explosive combustion and large parabolic reflectors to kill or incapacitate people through resonance.
The story is associated with reports of experimental acoustic devices in wartime Germany, but it has never achieved the evidentiary status of the better-documented systems discussed above. More importantly, the physics pose severe problems. Modern acoustic-weapons research shows that producing extreme acoustic pressures at substantial distances requires enormous source energy, while propagation losses and beam spreading limit practical effects (Altmann, 2001).
The appropriate historical treatment is therefore “reported experimental concept,” not “deployed Nazi superweapon.”
That distinction matters because the mythology of sonic weapons has consistently outrun the engineering.
The real acoustic weapon is often the information
Across this history, the most important applications of sound have rarely been the ones that resemble science fiction.
The Mark 24 Fido used sound to find and destroy a submarine.
The Ghost Army used sound to create an imaginary army.
Operation Wandering Soul used sound to create the psychological impression that the dead were speaking.
Operation JUST CAUSE used loudspeakers and radio to persuade, inform, negotiate and control the information environment.
LRAD and HyperSpike use directionality to extend speech and warning over long distances.
NIXIE uses sound to make an incoming torpedo interpret the acoustic environment incorrectly.
The Mosquito uses high-frequency sound to exploit differences in human hearing.
And contemporary naval systems combine acoustic sensors with radar, infrared and other systems to build a more complete picture of the environment.
There is therefore no single category called “the acoustic weapon.” There is an entire technological spectrum:
sound as signal; sound as sensor; sound as deception; sound as communication; sound as deterrence; sound as countermeasure; and, at sufficiently high intensity, sound as a source of injury.
The mythology begins with the last category because “sonic cannon” is a memorable phrase. The history is more consequential when viewed from the other end.
The decisive question has usually not been “How loud can the sound become?”
It has been:
“What can the listener be made to hear, believe, and do?”
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