Long Range Acoustic Device
   HOME

TheInfoList



OR:

A long-range acoustic device (LRAD), acoustic hailing device (AHD) or sound cannon is a specialized
loudspeaker A loudspeaker (commonly referred to as a speaker or, more fully, a speaker system) is a combination of one or more speaker drivers, an enclosure, and electrical connections (possibly including a crossover network). The speaker driver is an ...
that produces sound at high power for communicating at a distance. It has been used as a method of
crowd control Crowd control is a public security practice in which large crowds are managed in order to prevent the outbreak of crowd crushes, affray, fights involving drunk and disorderly people or riots. Crowd crushes in particular can cause many hundre ...
, which has caused permanent hearing damage, having an extremely high
decibel The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a Power, root-power, and field quantities, power or root-power quantity on a logarithmic scale. Two signals whos ...
capacity (up to 160 dB measured at one meter from the device). Other uses have included for negotiations in
siege A siege () . is a military blockade of a city, or fortress, with the intent of conquering by attrition, or by well-prepared assault. Siege warfare (also called siegecrafts or poliorcetics) is a form of constant, low-intensity conflict charact ...
situations; to deal with
piracy Piracy is an act of robbery or criminal violence by ship or boat-borne attackers upon another ship or a coastal area, typically with the goal of stealing cargo and valuable goods, or taking hostages. Those who conduct acts of piracy are call ...
at sea; for mass notification during
natural disaster A natural disaster is the very harmful impact on a society or community brought by natural phenomenon or Hazard#Natural hazard, hazard. Some examples of natural hazards include avalanches, droughts, earthquakes, floods, heat waves, landslides ...
s or other emergencies; and by defense forces, including several
navies A navy, naval force, military maritime fleet, war navy, or maritime force is the branch of a nation's armed forces principally designated for naval and amphibious warfare; namely, lake-borne, riverine, littoral, or ocean-borne combat operation ...
.


Overview

Acoustic hailing devices are acoustic devices capable of outputting intelligible sound at very high volumes. The distance at which acoustic hailing can be effective varies based on several factors including the sound level, directionality, and
frequency Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...
of the acoustic source, the sensitivity and directionality of the receiver, and the transmission channel environment. The sound level diminishes or attenuates with distance. Consequently, as a general rule, higher source levels have greater range. Acoustic hailing devices can come in two forms; # Directional models: These AHDs are characterized by their ability to create long-range, directional voice communications and warning tones. Their directionality is typically 5° to 60° radius conical at a 2  kHz tone. # Omnidirectional models: These acoustic hailing devices are capable of creating 360° voice communications and warning tones. These devices are capable of being heard over away from the emitter head.


Origin

The term ''acoustic hailing device'' came into common use following the
suicide attack A suicide attack (also known by a wide variety of other names, see below) is a deliberate attack in which the perpetrators knowingly sacrifice their own lives as part of the attack. These attacks are a form of murder–suicide that is ofte ...
on the while it was at a port in
Yemen Yemen, officially the Republic of Yemen, is a country in West Asia. Located in South Arabia, southern Arabia, it borders Saudi Arabia to Saudi Arabia–Yemen border, the north, Oman to Oman–Yemen border, the northeast, the south-eastern part ...
in 2000. Following this attack, the
United States Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...
established a requirement for an acoustic hailing device. The intent of this AHD was to provide the Navy with a means to establish the intent of an approaching vessel at a distance such that defensive measures could be taken should the vessel not heed a warning. One unique aspect of this requirement was that the sound needed to be focused so that it could be clearly directed at the approaching vessel.


Present

Since their inception in 2002, acoustic hailing devices have grown into a variety of applications. AHD uses include checkpoints,
crowd control Crowd control is a public security practice in which large crowds are managed in order to prevent the outbreak of crowd crushes, affray, fights involving drunk and disorderly people or riots. Crowd crushes in particular can cause many hundre ...
, maritime shipping, mass notification,
early warning system An early warning system is a warning system that can be implemented as a chain of information communication systems and comprises sensors, event detection and decision subsystems for early identification of hazards. They work together to fore ...
s, critical infrastructure protection, military applications and wildlife protection and control. Acoustic hailing devices are now fielded all over the world by various commercial, law enforcement, and military groups.


History

In October 2000 the , an American
guided missile destroyer A guided-missile destroyer (DDG) is a destroyer whose primary armament is guided missiles so they can provide anti-aircraft warfare screening for the fleet. The NATO standard designation for these vessels is DDG, while destroyers which have a pr ...
, was bombed in an attack by
al-Qaeda , image = Flag of Jihad.svg , caption = Jihadist flag, Flag used by various al-Qaeda factions , founder = Osama bin Laden{{Assassinated, Killing of Osama bin Laden , leaders = {{Plainlist, * Osama bin Lad ...
operatives, using a small boat packed with explosives. The naval personnel on Cole were unable to be sure that their messages could be heard by the approaching boat at a sufficient distance to possibly avert the attack. The ship was badly damaged, with 17 U.S. Navy sailors killed and 37 injured. Following this attack, navies around the world made several policy changes, while the American Technology Corporation (which was rebranded to LRAD Corporation in 2010 and to Genasys in late October 2019) created and developed the AHD market, which included the launch of its proprietary Long Range Acoustic Device, a type of acoustic hailing device, in 2003. Using this new technology, it became possible for naval personnel to contact approaching vessels which did not respond to radio calls from a distance of over , enabling them to respond appropriately in a timely manner and avert danger. Since then the technology has developed and expanded. Genasys launched its voice-based mass notification systems in 2012, and in 2019 its unified multichannel Critical Communications and Enterprise Safety system. LRAD devices have become widely used for communications, and increasingly for crowd control in a range of settings, including civil disturbances and protests.


Characteristics and measurements

Acoustic hailing devices differ from conventional speaker systems in three key ways: volume, clarity, and directionality. AHD manufacturers use different methods to measure their products, but a common standard has emerged.


Volume

Since sound attenuates with distance, extremely high outputs are required to achieve the required range. Acoustic hailing devices have an output of 135 decibels (dB) or greater. The acoustic level of the source is commonly expressed in terms of
sound pressure Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average or equilibrium) atmospheric pressure, caused by a sound wave. In air, sound pressure can be measured using a microphone, and in water with a hydrophon ...
level or SPL. SPL is a
logarithm In mathematics, the logarithm of a number is the exponent by which another fixed value, the base, must be raised to produce that number. For example, the logarithm of to base is , because is to the rd power: . More generally, if , the ...
ic measure of the rms sound pressure of a sound relative to a reference value. It is measured in
decibel The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a Power, root-power, and field quantities, power or root-power quantity on a logarithmic scale. Two signals whos ...
s (dB) above a standard reference level. For reference, at a distance of 1 meter, a normal talking voice is approximately 50 dB and a jet engine at 30 meters is 150 dB.


Clarity

A principal weakness of common speaker systems and bullhorns is their clarity. Their horns and cones create sound that is distorted or out of phase. This results in the common "
Charlie Brown Charles "Charlie" Brown is the Protagonist, principal character of the comic strip ''Peanuts'', syndicated in daily newspaper, daily and Sunday newspapers in numerous countries all over the world. Depicted as a "lovable loser", Charlie Brown ...
" effect, where the message is muffled and misunderstood, analogous to the muted brass squawks representing the unintelligible voices of adults in animated ''
Peanuts ''Peanuts'' (briefly subtitled ''featuring Good ol' Charlie Brown'') is a print syndication, syndicated daily strip, daily and Sunday strip, Sunday American comic strip written and illustrated by Charles M. Schulz. The strip's original run ext ...
'' specials. AHDs create sound that is in phase. Because of this, sound emitted from acoustic hailing devices is intelligible at distance. Clarity is difficult to measure, since it is a subjective reference. However, different scales have been created to compare devices. A common measurement is the speech transmission index (STI). STI ratings range from 0–1.0, with 1.0 being perfect clarity.


Focus

AHDs are lastly characterized by directionality. To ensure messages are broadcast to the target, AHDs shape sound into a 30–60° audio beam. This shaping is accomplished through the design of the
transducer A transducer is a device that Energy transformation, converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another. Transducers are often employed at the boundaries of automation, M ...
s as well as various reflective horns. The focus of an AHD is typically measured at the frequency of peak directionality. This is typically in the 1–2 kHz range. Not all frequencies of sound are able to be directed equally. Lower frequencies in the bass range are difficult to form. As such, their directionality may be a 40 degree radius or more depending on the design of the AHD.


Specifications and functionality

LRAD devices are made by Genasys. , the company claims its LRAD products meet the following specifications: * 30° audible transmission ranges out to 5,000 meters * 60º–360° audible mass notification coverage over areas up to LRAD devices include hand-held devices, as well as those mounted on
helicopter A helicopter is a type of rotorcraft in which Lift (force), lift and thrust are supplied by horizontally spinning Helicopter rotor, rotors. This allows the helicopter to VTOL, take off and land vertically, to hover (helicopter), hover, and ...
s, motor vehicles and ships. The parameter "ka", which is the
wave number In the physical sciences, the wavenumber (or wave number), also known as repetency, is the spatial frequency of a wave. Ordinary wavenumber is defined as the number of wave cycles divided by length; it is a physical quantity with dimension of r ...
multiplied by the speaker radius, is often used to characterize sound source directivity. For this source, ka=19 at 2.5 kHz, and according to the LRAD data sheet, the beam angle of about 30 degrees total is what is predicted for a regular loudspeaker. Small spherical "point-source" acoustic devices follow the known
inverse square law In science, an inverse-square law is any scientific law stating that the observed "intensity" of a specified physical quantity is inversely proportional to the square of the distance from the source of that physical quantity. The fundamental cau ...
, which predicts the loss of 6
decibel The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a Power, root-power, and field quantities, power or root-power quantity on a logarithmic scale. Two signals whos ...
s (dB) per doubling of distance from the source, solely due to geometric spreading. Large speakers (or large arrays), such as these, have an
interference Interference is the act of interfering, invading, or poaching. Interference may also refer to: Communications * Interference (communication), anything which alters, modifies, or disrupts a message * Adjacent-channel interference, caused by extra ...
pattern in the nearfield which produces peaks 6 dB higher than the output
pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and eve ...
and nulls where the pressure is essentially zero.Blackstock, David T. 2000. Fundamentals of Physical Acoustics, p.456,
John Wiley and Sons John Wiley & Sons, Inc., commonly known as Wiley (), is an American multinational publishing company that focuses on academic publishing and instructional materials. The company was founded in 1807 and produces books, journals, and encyclop ...
.
The larger the speaker, and the higher the frequency, the longer the effective nearfield. The nearfield for this device is approximately . An LRAD can thus emit a targeted "beam" of sound at very high volume, up to 160 dB at one meter from the device. This is louder than standing behind a
jet engine A jet engine is a type of reaction engine, discharging a fast-moving jet (fluid), jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition may include Rocket engine, rocket, Pump-jet, water jet, and ...
taking off, or a nearby
gunshot A gunshot is a single discharge of a gun, typically a man-portable firearm, producing a visible flash, a powerful and loud shockwave and often chemical gunshot residue. The term can also refer to a ballistic wound caused by such a discharge ...
.


Use

Following the impetus for its initial development, 25 navies have adopted the use of LRADs , to provide protection for their vessels. Navy personnel can contact approaching vessels from over and respond defensively if necessary. They are also used by
coast guard A coast guard or coastguard is a Maritime Security Regimes, maritime security organization of a particular country. The term embraces wide range of responsibilities in different countries, from being a heavily armed military force with cust ...
s,
naval base A naval base, navy base, or military port is a military base, where warships and naval ships are docked when they have no mission at sea or need to restock. Ships may also undergo repairs. Some naval bases are temporary homes to aircraft that usu ...
s, commercial vessels, and in ports. Genasys offers its products for the following categories of use on its U.S. website: defense,
law enforcement Law enforcement is the activity of some members of the government or other social institutions who act in an organized manner to enforce the law by investigating, deterring, rehabilitating, or punishing people who violate the rules and norms gove ...
, fire and rescue services,
border security Border control comprises measures taken by governments to monitor and regulate the movement of people, animals, and goods across land, air, and maritime borders. While border control is typically associated with international borders, it als ...
, protection of
critical infrastructure Critical infrastructure, or critical national infrastructure (CNI) in the UK, describes infrastructure considered essential by governments for the functioning of a society and economy and deserving of special protection for national security. ...
, and maritime safety. its products are in use in 100 countries. The Asia-Pacific website is focused on
emergency management Emergency management (also Disaster management) is a science and a system charged with creating the framework within which communities reduce vulnerability to hazards and cope with disasters. Emergency management, despite its name, does not actu ...
during
natural disaster A natural disaster is the very harmful impact on a society or community brought by natural phenomenon or Hazard#Natural hazard, hazard. Some examples of natural hazards include avalanches, droughts, earthquakes, floods, heat waves, landslides ...
s such as bushfires. It is not categorized as a defense item, and does not require an export license. The technology can also be used to deter wildlife from airport runways, as at
Changi Airport Singapore Changi Airport ( ; ) is the primary international airport that serves the country of Singapore, and is one of the largest transportation hubs in Asia. More than 100 airlines operate from the airport, with flights to destinations in A ...
in
Singapore Singapore, officially the Republic of Singapore, is an island country and city-state in Southeast Asia. The country's territory comprises one main island, 63 satellite islands and islets, and one outlying islet. It is about one degree ...
, and to protect gas and oil platforms from
fishing boats A fishing vessel is a boat or ship used to fishing, catch fish and other valuable nektonic aquatic animals (e.g. shrimps/prawns, krills, coleoids, etc.) in the sea, lake or river. Humans have used different kinds of surface vessels in commercial ...
, birds and security threats. There are two basic ways of using LRAD devices: for voice amplification and as an alert. The technology used in " siren mode" (called an "alert tone" by Genasys), primarily for usage in emergency situations, has also been used for crowd control. In this mode, it allows sound transmission at around 2,000–4,000
Hertz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or Cycle per second, cycle) per second. The hertz is an SI derived unit whose formal expression in ter ...
, which causes maximum discomfort for the people targeted, as this is the frequency range at
human hearing Hearing, or auditory perception, is the ability to perceive sounds through an organ, such as an ear, by detecting vibrations as periodic changes in the pressure of a surrounding medium. The academic field concerned with hearing is auditory sc ...
is most sensitive. Although sometimes referred to as an
Active Denial System The Active Denial System (ADS) is a directed-energy weapon developed by the United States armed forces, U.S. military, designed for area denial, perimeter security and crowd control. Informally, the weapon is also called the heat ray since it wo ...
, the latter is based on a different technology, in which millimetre-wave radiation causes nerve receptors in the skin to feel heat, via
dielectric heating Dielectric heating, also known as electronic heating, radio frequency heating, and high-frequency heating, is the process in which a radio frequency (RF) alternating electric field, or radio wave or microwave electromagnetic radiation heats a diel ...
.


Risks

Acoustic hailing devices are being used as
weapons A weapon, arm, or armament is any implement or device that is used to deter, threaten, inflict physical damage, harm, or kill. Weapons are used to increase the efficacy and efficiency of activities such as hunting, crime (e.g., murder), law ...
. The human
ear In vertebrates, an ear is the organ that enables hearing and (in mammals) body balance using the vestibular system. In humans, the ear is described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear co ...
can typically stand a sound pressure level of 120 dB before feeling pain. AHDs are capable of 135 dB or more of acoustic energy.
OSHA The Occupational Safety and Health Administration (OSHA; ) is a regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. The United States Congress established ...
states that any sound pressure level over 90 dB requires hearing protection. As volume increases so does the chance of hearing loss. The effective non-lethal range of an AHD depends on the total acoustic output of the unit. Typically, this range is or less. In addition to its "voice" feature, which acts as a
loudspeaker A loudspeaker (commonly referred to as a speaker or, more fully, a speaker system) is a combination of one or more speaker drivers, an enclosure, and electrical connections (possibly including a crossover network). The speaker driver is an ...
, the LRAD has an "alert" feature, which emits loud chirping or beeping sounds, which can be used at the top of the decibel range of the device. These sounds have been reported to cause pain and hearing damage. The use of the alert function for crowd control has been described as a "sound cannon" or sonic weapon, although this has been denied by the manufacturer. The sound can be targeted within a narrow and specific range that does not impact those operating the device or standing next to it.
Civil liberties Civil liberties are guarantees and freedoms that governments commit not to abridge, either by constitution, legislation, or judicial interpretation, without due process. Though the scope of the term differs between countries, civil liberties of ...
organizations are concerned about its use by police forces, and its use has been contested in law courts in the United States. One concern is that police officers are not receiving enough training in its use. Due to potential risks and a lack of studies on the health impact of sonic weapons, the
American Civil Liberties Union The American Civil Liberties Union (ACLU) is an American nonprofit civil rights organization founded in 1920. ACLU affiliates are active in all 50 states, Washington, D.C., and Puerto Rico. The budget of the ACLU in 2024 was $383 million. T ...
recommended in a fact sheet that their use in protests be suspended. Law enforcement organizations and the manufacturer claim that LRAD systems are primarily designed for long-range communications; however, the device has an extremely high
decibel The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a Power, root-power, and field quantities, power or root-power quantity on a logarithmic scale. Two signals whos ...
capacity and has been controversially used as a less-lethal weapon for crowd control. Police usually use models that are not quite as powerful as the military-grade version; however, generating levels ranging from 137 dB to 154 dB, they are capable of causing pain, disorientation,
nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. It can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat. Over 30 d ...
,
migraine Migraine (, ) is a complex neurological disorder characterized by episodes of moderate-to-severe headache, most often unilateral and generally associated with nausea, and light and sound sensitivity. Other characterizing symptoms may includ ...
s, and permanent hearing damage. The New York City Police Department's LRAD use was to be challenged in US federal court in 2020. In the lawsuit, five protestors and photographers sued the city, alleging that they'd experienced migraines, sinus pain, dizziness, facial pressure and ear ringing after they were exposed to the LRAD's alert tone. The city settled the lawsuit in 2021, with an agreement that the police would be banned from using the alert feature and that rules would be created on how and when the police could use LRADs. The city also agreed to pay $98,000 in damages to the plaintiffs, as well as $650,000 in legal fees.


Deployments


Australia

By mid-2016, most Australian police forces had acquired LRADs (
Queensland Police The Queensland Police Service (QPS) is the principal law enforcement agency responsible for policing the Australian state of Queensland. In 1990, the Queensland Police Force was officially renamed the Queensland Police Service and the old motto ...
said that they had been using it since 2009), and concerns were raised about their use for crowd control. However, before 2020, there was no use of the LRAD in public situations; most usage had been by the various police forces for communications during
natural disaster A natural disaster is the very harmful impact on a society or community brought by natural phenomenon or Hazard#Natural hazard, hazard. Some examples of natural hazards include avalanches, droughts, earthquakes, floods, heat waves, landslides ...
s or for negotiations with
hostage A hostage is a person seized by an abductor in order to compel another party, one which places a high value on the liberty, well-being and safety of the person seized—such as a relative, employer, law enforcement, or government—to act, o ...
-takers in a
siege A siege () . is a military blockade of a city, or fortress, with the intent of conquering by attrition, or by well-prepared assault. Siege warfare (also called siegecrafts or poliorcetics) is a form of constant, low-intensity conflict charact ...
, where it was too dangerous to approach a suspect. In June 2020, during the Black Lives Matter protests in New South Wales,
NSW Police The New South Wales Police Force is a law enforcement agency of the state of New South Wales, Australia, established in 1862. With more than 17,000 police officers, it is the largest police organisation in Australia, policing an area of 801,60 ...
used LRADs in a different way for the first time, and it has been used at other anti-racism protests in Australia. The device came to the attention of the wider public when it was used at the 2022 anti-vaccine mandate Canberra protests in "loud hailer" mode for voice messages to be announced to the protesters, and there was speculation among protesters regarding purported harms from its use. However, there was no evidence that it was used as a siren. In addition, some reports appeared to confuse the LRAD with other crowd control devices, such as the
Active Denial System The Active Denial System (ADS) is a directed-energy weapon developed by the United States armed forces, U.S. military, designed for area denial, perimeter security and crowd control. Informally, the weapon is also called the heat ray since it wo ...
; one activist claimed that "
supersonic Supersonic speed is the speed of an object that exceeds the speed of sound (Mach 1). For objects traveling in dry air of a temperature of 20 °C (68 °F) at sea level, this speed is approximately . Speeds greater than five times ...
weapons" had been used.


Czech Republic

On June 26, 2015, Czech Special Forces Police may have deployed an LRAD 500X during anti-immigration and anti-Islam protests in
Brno Brno ( , ; ) is a Statutory city (Czech Republic), city in the South Moravian Region of the Czech Republic. Located at the confluence of the Svitava (river), Svitava and Svratka (river), Svratka rivers, Brno has about 403,000 inhabitants, making ...
, the second largest city in the
Czech Republic The Czech Republic, also known as Czechia, and historically known as Bohemia, is a landlocked country in Central Europe. The country is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the south ...
. Police in
Prague Prague ( ; ) is the capital and List of cities and towns in the Czech Republic, largest city of the Czech Republic and the historical capital of Bohemia. Prague, located on the Vltava River, has a population of about 1.4 million, while its P ...
used a vehicle-mounted LRAD on November 17, 2020, to repeatedly alert protesters on Wenceslas Square to follow COVID restrictions and wear masks. On that day, police supervised several rallies, meetings and demonstrations. Thousands of participants gathered at the largest protests in the Old Town Square. The police and a Prague City Hall representative used an LRAD to repeatedly call upon demonstrators to follow COVID public safety protocols and to comply with security measures. During a November 25, 2021 march from the center of Prague to the local soccer stadium for a Europa Conference League match, Prague police and regional Czech law enforcement officers utilized vehicle mounted LRADs to broadcast frequent warnings against the use of pyrotechnics by the large crowds. Prague police officers utilized a vehicle-mounted LRAD to issue more than 500 warnings to revelers not to set off pyrotechnics during downtown December 31, 2021 - January 1, 2022 New Year's Eve celebrations. A vehicle-mounted LRAD was deployed by police in Prague on March 11, 2023, to communicate to and warn away demonstrators from the National Museum.


Greece

Hellenic Police The Hellenic Police (, ''Ellinikí Astynomía'', abbreviated ) is the national police service and one of the three security forces of Greece (the others being the Hellenic Fire Service and the Hellenic Coast Guard). It is a large agency with res ...
acquired two LRAD systems to be used at the Evros border. These were tested after the March 2020 migrant crisis at the border, triggered by the Turkish government. They are to be used as a deterrent against illegal border entry, as a notification system, as well as to handle aggressive actions against the Hellenic Armed Forces.


Japan

Japan's Coast Guard used Long Range Acoustic Devices and other methods to expel a North Korean fishing flotilla from its waters in September 2017. In February 2009, the Japanese whaling fleet operating in Antarctic waters near Australia installed LRADs on their vessels. The device was used against activists of the
Sea Shepherd Conservation Society The Sea Shepherd Conservation Society (SSCS) is a non-profit, marine conservation activism organization based in Friday Harbor, Washington, Friday Harbor on San Juan Island, Washington, in the United States. Sea Shepherd employs direct action t ...
. The Japanese fleet later escalated the use of LRAD, deploying it against a Sea Shepherd helicopter carrying a camera crew. Sea Shepherd noted that they had an LRAD of their own, but as of early 2010, had not put it into use other than to play a recording of " Ride of the Valkyries" in the manner of attacking U.S. Army helicopters depicted in the 1979 film ''
Apocalypse Now ''Apocalypse Now'' is a 1979 American psychological epic war film produced and directed by Francis Ford Coppola. The screenplay, co-written by Coppola, John Milius, and Michael Herr, is loosely inspired by the 1899 novella '' Heart of Darkn ...
''.


New Zealand

During the dispersion of New Zealand's parliament protest in March 2022, LRAD were used by New Zealand police against the protesters. A document released under the Official Information Act (OIA), revealed two long range acoustic devices (LRADs) were deployed at the Parliament protest on March 2.


Poland

LRAD was present, but not used because of current legal regulations during protests in Poland, including Million Marijuana March 2011 and Marsz Niepodległości (National Independence Day March) 2011 and 2012. Lacking a way to utilize the LRADs purchased to their full potential sparked an investigation suspecting corruption behind their acquisition. National Police Headquarters spokesman Mariusz Sokolowski defended the purchase of LRAD. He also stressed that the police decided to make this investment because, "We needed good sound reinforcement equipment. With numerous demonstrations and gatherings, police need a public address system that allows you to reach thousands of people." Municipal police in Gdańsk, Poznań, Kołobrzeg and other cities in Poland used LRAD systems to deliver COVID-19 notifications.


Serbia

In December 2022 N1 reported that the Ministry of Internal Affairs acquired LRAD systems. The Ministry of Internal Affairs did not confirm or deny the report. Opposition officials and Serbian rights groups stated that a military-grade sonic weapon was used during peaceful Serbian anti-corruption protests on March 15, 2025. Serbian police and the defense ministry denied that the weapon was used, as did president
Aleksandar Vučić Aleksandar Vučić, (born 5 March 1970) is a Serbian politician serving as President of Serbia since 2017. A founding member of the Serbian Progressive Party (SNS), he previously served as President of the SNS from 2012 to 2023, Deputy Prim ...
, who called it a "wicked lie" aimed at destroying Serbia.


Singapore

LRAD is used by the Singapore Changi Airport to disperse birds and wildlife from runways.


Spain

Local police in Leganés, Spain used a vehicle-mounted LRAD to deliver alerts and notifications to residents during the country-wide COVID-19 lockdown. According to Citizen Security, Communication and local government spokesman, Oscar Oliveira, "Because the acoustic device can be heard inside of houses, we can inform older residents with mobility issues that all municipal resources are available through the Citizen Attention Service by calling 010."


United Kingdom

It was confirmed by the
Ministry of Defence A ministry of defence or defense (see American and British English spelling differences#-ce.2C -se, spelling differences), also known as a department of defence or defense, is the part of a government responsible for matters of defence and Mi ...
on May 11, 2012, that an LRAD would be deployed in London during the 2012 Summer Olympic Games. It was spotted fixed to a landing craft on the
River Thames The River Thames ( ), known alternatively in parts as the The Isis, River Isis, is a river that flows through southern England including London. At , it is the longest river entirely in England and the Longest rivers of the United Kingdom, s ...
.


United States

An LRAD was present, but not used, during protests of the 2004 Republican National Convention in
New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...
. LRAD was present and used when the New York City Police department raided and destroyed the
Occupy Wall Street Occupy Wall Street (OWS) was a left-wing populist movement against economic inequality, capitalism, corporate greed, big finance, and the influence of money in politics that began in Zuccotti Park, located in New York City's Financial ...
encampment from
Zuccotti Park Zuccotti Park (formerly Liberty Plaza Park) is a publicly accessible park in the Financial District of Lower Manhattan in New York City. It is located in a privately owned public space (POPS) controlled by Brookfield Properties and Goldman S ...
to disrupt and disperse the crowd before arresting or ejecting them on the morning of 15 November 2011. On December 5, 2014, the
NYPD The City of New York Police Department, also referred to as New York City Police Department (NYPD), is the primary law enforcement agency within New York City. Established on May 23, 1845, the NYPD is the largest, and one of the oldest, munic ...
utilized an LRAD, notifying approximately 100 protestors to disperse, during the protest of the police killing of Eric Garner in Midtown Manhattan. The NYPD used a Long Range Acoustic Device during the Baltimore solidarity rally in Union Square on April 29, 2015. An NYPD pickup truck equipped with an LRAD parked near protesters and broadcast a looped warning message about staying off the streets and not blocking the sidewalks. Rochester NY police used verbal warnings and an LRAD to help disperse disorderly crowds during the August 2019 Puerto Rican Festival. Rochester, NY police used a Long Range Acoustic Device to make announcements to protesters that they were unlawfully in the roadway and obstructing traffic on September 12, 2020. The device was also used at the September 16, 2020 protest in front of Rochester city hall. The Washington, D.C. Metropolitan Police Department used a LRAD at the January 21, 2017 Women's March. Protesters at the June 1, 2020 Washington, D.C. George Floyd protests said police gave little or no warning before employing aggressive tactics against them. A 2015 settlement requires federal police to give large crowds several loud dispersal orders before deploying chemical irritants and other dispersion tools. Using an LRAD to issue loud protest dispersal orders would have complied with the 2015 settlement requirement. In September 2020, it was revealed that federal officials had explored the use of the device and the
Active Denial System The Active Denial System (ADS) is a directed-energy weapon developed by the United States armed forces, U.S. military, designed for area denial, perimeter security and crowd control. Informally, the weapon is also called the heat ray since it wo ...
("heat ray") to disperse civilians protesting outside the White House in June of that year, but had been advised that the
National Guard National guard is the name used by a wide variety of current and historical uniformed organizations in different countries. The original National Guard was formed during the French Revolution around a cadre of defectors from the French Guards. ...
was not currently in possession of either device. LRAD was reportedly used by the Oakland Police Department during the clearance of the
Occupy Oakland Occupy Oakland refers to a collaboration and series of Demonstration (people), demonstrations in Oakland, California, Oakland, California, that started in October 2011. As part of the Occupy movement, protesters have staged Occupation (protest), ...
encampment on the morning of 25 October 2011. Police in San Diego, California, used an LRAD on May 27, 2016, to order anti-Trump protesters to disperse. The Mendocino County (California) Board of Supervisors approved the purchase of a Long Range Acoustic Device for the Mendocino County Sheriff's Office on April 18, 2017. Sheriff Tom Allman said the device would aid in searches for missing persons, most often hunters and mushroom pickers, which cost the county tens of thousands of dollars. He said the LRAD might have made the intense 2011 manhunt for Aaron Bassler a little easier, and that it could be used to warn of a tsunami. MCSO found LRAD useful out of a low-flying plane, and it could help in a barricaded-person situation to communicate from the outside of the building. The Greensboro, North Carolina Police Department (GPD) purchased an LRAD 300X and demonstrated it for reporters in November 2015. Jonathan Franks, a GPD captain, said that it could be used for alerts for everything from riots to missing children to weather disasters, and that it could save lives in some cases. The Charlotte-Mecklenburg, North Carolina Police Department Crisis Intervention Team and SWAT negotiators used a long-range acoustic device to talk a man down from an energized electrical tower. The Phoenix, Arizona city council approved the purchase of two LRAD 500X systems in November 2018 "to give clear and concise messages to groups of people whenever we find it necessary". Police utilized a Long Range Acoustic device to declare an unlawful assembly in downtown Phoenix, Arizona, on May 28, 2020, during the
George Floyd protests The George Floyd protests were a series of protests, riots, and demonstrations against police brutality that began in Minneapolis in the United States on May 26, 2020. The protests and civil unrest began in Minneapolis as Reactions to the mu ...
. Multiple announcements were made in English and Spanish. The Salisbury, Maryland Police Department acquired an LRAD in October 2013 with proceeds from their speed cameras. On February 17, 2017, the Princess Anne Police Department deployed its LRAD system at the request of the Maryland State Police to disperse an unruly concert crowd on the campus of the University of Maryland Eastern Shore. The Columbus, Ohio Police Department (CPD) demonstrated a Long Range Acoustic Device to the local media on November 21, 2016. CPD expects to use the device for crowd control, barricaded suspect operations, and to communicate to residents during emergencies and natural disasters. The Cuyahoga County Sheriff's Department purchased Long Range Acoustic Devices to improve the department's ability to issue dispersal orders clearly over long distances. The purchases resulted from the department's after-action report of the May 30, 2020 riot in downtown Cleveland, Ohio. The
Seattle Police Department The Seattle Police Department (SPD) is the principal police force, law enforcement agency of the city of Seattle, Washington, United States. It is responsible for the entire city except for the campus of the University of Washington (which is und ...
in Washington purchased an LRAD in response to claims that it did not adequately communicate orders to demonstrators during the summer 2020 protests. SPD's use of its LRAD was alleged to have caused ear damage to a peaceful demonstrator, although an internal SPD review deemed the allegations to be unsustained. After receiving feedback from protesters who said commands from on-scene officers were not clear or loud enough, the Seattle, Washington mayor's office recommended purchasing an LRAD. LRADs were used by the Pittsburgh PD in Pennsylvania during protests at the G20 Summit in September 2009. This was the first time the LRAD was used during a protest in the U.S. LRAD was deployed during a march against
NATO The North Atlantic Treaty Organization (NATO ; , OTAN), also called the North Atlantic Alliance, is an intergovernmental organization, intergovernmental Transnationalism, transnational military alliance of 32 Member states of NATO, member s ...
's actions and policies in Chicago, Illinois on May 20, 2012, at Michigan Ave. & Cermack. St. Louis County police used LRAD during protests surrounding the police shooting of Michael Brown in
Ferguson, Missouri Ferguson is a city in St. Louis County, Missouri, St. Louis County, Missouri, United States. It is part of the Greater St. Louis metropolitan area. Per the 2020 United States census, 2020 census, the population was 18,527, and is predominantly Bla ...
. Myrtle Beach, South Carolina police obtained two LRAD systems through a federal grant in March 2015. Myrtle Beach police captain Marty Brown told the Myrtle Beach city council that "his department is getting the LRADs to enhance their communication capabilities be it with large crowds or for emergency announcements such as evacuation orders." The New Jersey State Police used an armored-vehicle-mounted LRAD to communicate with crowds denied entry to a June 7, 2015 concert after they began throwing bottles and tried to rush the gates outside MetLife Stadium. Police from several agencies, including North Dakota state troopers, the National Guard, and other law enforcement agencies from surrounding counties and states deployed two LRADs to clear a protest camp and blockades along Highway 1806. "Long Range Acoustic Devices, which emit an ear-splitting whine, were used intermittently throughout the day" one reporter wrote. An LRAD was present again on November 20, 2016, at the bridge just north of the protesters camp on highway 1806. During the same period, the LRAD was used at a protest in front of the Arkansas State Capitol. The
Portland Police Bureau The Portland Police Bureau (PPB), officially the Portland Bureau of Police, is the law enforcement agency of the city of Portland, Oregon, Portland, the largest city in the U.S. state of Oregon. As of September 2024, the Bureau has around 800 ...
in Oregon used a vehicle-mounted LRAD during the protests there following the
murder of George Floyd On May 25, 2020, George Floyd, a 46-year-old Black American man, was murdered in Minneapolis by Derek Chauvin, a 44-year-old White police officer. Floyd had been arrested after a store clerk reported that he made a purchase using a c ...
on June 4, 2020, and on other occasions during the protests. A BearCat-mounted LRAD was used to emit voice messages and high-pitched sirens in
Kenosha, Wisconsin Kenosha () is a city in Kenosha County, Wisconsin, United States, and its county seat. It is the List of cities in Wisconsin, fourth-most populous city in Wisconsin, with a population of 99,986 at the 2020 United States census, 2020 census. S ...
on August 24, 2020, in front of the Kenosha County Courthouse to disperse crowds assembled in Civic Center Park as part of the Jacob Blake protests. On March 6, 2021, the Boulder Police Department used a toned warble noise from an LRAD in an effort to disperse a crowd of up to 800 students from the
University of Colorado Boulder The University of Colorado Boulder (CU Boulder, CU, or Colorado) is a public research university in Boulder, Colorado, United States. Founded in 1876, five months before Colorado became a state, it is the flagship university of the University o ...
. The University Hill Incident occurred when code enforcement and members of Boulder Police's Neighborhood Impact Team were unable to disperse partygoers who were congregating against Boulders public health order. LRAD was used after students and other partygoers began throwing rocks at SWAT vehicles and officers. On April 12, 2021, the Brooklyn Center, Minnesota Police Department deployed a vehicle mounted LRAD outside of its headquarters to announce curfew violations and dispersal orders to a large crowd protesting the death of Daunte Wright. On July 3, 2021, Massachusetts State Police utilized an LRAD to secure a group of 11 suspects involved in the
Sovereign Citizen movement The sovereign citizen movement (also SovCit movement or SovCits) is a loose group of anti-government activists, conspiracy theory, conspiracy theorists, vexatious litigants, tax protesters and financial scammers found mainly in English-speakin ...
. The group identified themselves as part of the "Rise of the Moors" movement, or "Moorish Americans". The self styled militia group was traveling between Rhode Island and Maine when an MSP trooper came across their convoy refueling. The group had multiple firearms in their possession, and admitted to not having proper carrying requirements. Several fled into the surrounding forest, at which point the LRAD was deployed. The group was taken into custody without further incident. The Oklahoma County, Oklahoma Sheriff's Office Tactical Team used a vehicle-mounted LRAD on November 22, 2021, to serve a search warrant on a residence suspected of being used for drug trafficking.


Mass notification


Australia

Genasys has supplied its NEWS mass notification service in Australia since 2013, when it partnered with
Nokia Nokia Corporation is a Finnish multinational corporation, multinational telecommunications industry, telecommunications, technology company, information technology, and consumer electronics corporation, originally established as a pulp mill in 1 ...
to deliver emergency notifications via
SMS Short Message Service, commonly abbreviated as SMS, is a text messaging service component of most telephone, Internet and mobile device systems. It uses standardized communication protocols that let mobile phones exchange short text messages, t ...
, following the disastrous consequences of the Black Saturday bushfires in 2009.


Germany

In the first half of 2020, Bad Homburg's fire brigade and city police used an LRAD 100X system more than 60 times to deliver COVID-19 information.


United States

Menlo Park and Atherton, California police and fire officials attended a 'sound off' between a siren installation and an LRAD 360XT mobile voice mass notification system in April 2018. "The side by side test was very helpful and everyone agreed that the LRAD system completely outperformed the older siren system," said Fire District Emergency Manager Ryan Zollicoffer. "Not only because of the voice capability, but the modular-mobility benefit is something that appeals to first responders because it can be used for a variety of public safety purposes and better moved around if that's needed or desired." The Menlo Park Fire District demonstrated its Long Range Acoustic Device (LRAD) community notification system on April 18, 2019. The fire district also showed how the ShakeAlert system could eventually be tied together with its LRAD to provide area wide audible alerts for earthquake, flood, fire and other emergencies. "ShakeAlert will notify and protect our Station firefighters, but we also believe coupled with the LRAD public address system, it can help to bridge the 'notification gap' as another important public safety tool and option for community early warning messaging for earthquakes as well as for fire and flooding information and evacuation signaling," said Fire Chief Harold Schapelhouman. The City of Laguna Beach, California, installed LRAD speaker sirens in 2018. The systems alert the downtown and Main Beach areas during an emergency where the public needs to take immediate action. In June 2019, Mill Valley, California, became the first city in the Bay Area to replace its sirens with LRAD community notification systems. The combined siren loudspeakers receive emergency messages via satellite and have backup batteries if the power fails. The Mill Valley Fire Department began testing its city's new LRAD installations on June 27, 2019. LRAD systems project both siren and voice recordings to alert and inform community members during large-scale disasters. The Long Range Acoustic Devices replaced siren-only systems in five Mill Valley, California locations. "We believe that the purchase and installation of LRAD goes a long way to improve the resiliency and redundancy of our communication systems," Mill Valley Fire Chief Tom Welch said. "LRAD systems are highly effective in communicating warnings, instructions, and notifications throughout incident sites and over vast areas during life-threatening events." The City of Newport Beach plans to spend $200,000 to replace three rusty tsunami warning sirens on the Balboa Peninsula with LRAD siren/public address systems. The LRAD systems are expected to be installed by the end of 2019. In October 2020, Laguna Beach, California, tested its expanded outdoor warning system of 13 Long Range Acoustic Devices mounted on buildings throughout the city. The solar-powered devices broadcast recorded evacuation messages in case cell service is disabled during a disaster. Seven new LRAD emergency siren systems are scheduled for installation in southern Marin County in 2022. The Berkeley, California city council approved the installation of a Genasys outdoor warning system to alert residents of fires, earthquakes, tsunamis and other disasters. The system is capable of running on solar-powered battery backup and being controlled remotely via satellite. Public safety officials in Berkeley, California unveiled the city's new Genasys emergency warning network during the September 17, 2023 Fire Ready Fest. Ten systems that broadcast both sirens and voice messages have been installed on buildings throughout Berkeley to provide another layer of reaching residents and visitors in the event of serious emergencies. Five more systems are projected to be installed by early 2024.


High seas anti-piracy

On November 5, 2005, the luxury cruise ship '' Seabourn Spirit'' employed an LRAD to repel
pirate Piracy is an act of robbery or criminal violence by ship or boat-borne attackers upon another ship or a coastal area, typically with the goal of stealing cargo and valuable goods, or taking hostages. Those who conduct acts of piracy are call ...
s who attacked the vessel with
rocket-propelled grenade A rocket-propelled grenade (RPG), also known colloquially as a rocket launcher, is a Shoulder-fired missile, shoulder-fired anti-tank weapon that launches rockets equipped with a Shaped charge, shaped-charge explosive warhead. Most RPGs can ...
s about off the coast of
Somalia Somalia, officially the Federal Republic of Somalia, is the easternmost country in continental Africa. The country is located in the Horn of Africa and is bordered by Ethiopia to the west, Djibouti to the northwest, Kenya to the southwest, th ...
. The effectiveness of this device during the attack is not completely clear, but the pirates did not succeed in boarding the vessel and eventually fled. The Liberian-flagged vessel was attacked on November 28, 2008. The security detachment aboard ''Biscaglia'' was reported to have used an LRAD device in an effort to repel attackers armed with
assault rifle An assault rifle is a select fire rifle that uses an intermediate cartridge, intermediate-rifle cartridge and a Magazine (firearms), detachable magazine.C. Taylor, ''The Fighting Rifle: A Complete Study of the Rifle in Combat'', F.A. Moyer '' ...
s and rocket-propelled grenades. Following a one-sided shootout, the ship was seized and the unarmed security contractors abandoned ship leaving the ship and crew to the pirates. The incident caused the usefulness of LRADs to be called into question by ''
Lloyd's List ''Lloyd's List'' is one of the world's oldest continuously running journals, having provided weekly shipping news in London as early as 1734. It was published daily until 2013 (when the final print issue, number 60,850, was published), and i ...
''.David Osler, (2 December 2008)
"Sonic solution may not be a sound investment"
''Lloyd's List''. London: Informa. Retrieved 13 April 2011.
The security detachment's reported use of LRAD is not completely clear as ''
The Wall Street Journal ''The Wall Street Journal'' (''WSJ''), also referred to simply as the ''Journal,'' is an American newspaper based in New York City. The newspaper provides extensive coverage of news, especially business and finance. It operates on a subscriptio ...
'' makes no mention of LRAD being used during the incident. In January 2011, the ''Spirit of Adventure'', a cruise ship sailing through the
Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...
, deployed an LRAD system as part of its defensive measures when being pursued by pirates. S/Y Hideaway used an LRAD in 2016 to deter suspected pirates in the
Gulf of Aden The Gulf of Aden (; ) is a deepwater gulf of the Indian Ocean between Yemen to the north, the Arabian Sea to the east, Djibouti to the west, and the Guardafui Channel, the Socotra Archipelago, Puntland in Somalia and Somaliland to the south. ...
.


Major users

* : Used for the first time in April 2019 during the pacific walk against Bouteflika on the Algerian population * :
Victoria Police Victoria Police is the primary law enforcement agency of the Australian States and territories of Australia, state of Victoria (Australia), Victoria. It was formed in 1853 and currently operates under the ''Victoria Police Act 2013''. , Victor ...
, the
Western Australian Police The Western Australia Police Force, colloquially WAPOL, provides police services throughout the state of Western Australia to a population of 2.66 million people, of which 2.11 million reside in the Perth Metropolitan Region. Western Australia h ...
, the
South Australia Police South Australia Police (SAPOL) is the police force of the Australian States and territories of Australia, state of South Australia. SAPOL is an independent statutory agency of the Government of South Australia directed by the Commissioner of Po ...
, the
Queensland Police Service The Queensland Police Service (QPS) is the principal law enforcement agency responsible for policing the Australian state of Queensland. In 1990, the Queensland Police Force was officially renamed the Queensland Police Service and the old motto ...
and the
Australian Federal Police The Australian Federal Police (AFP) is the principal Federal police, federal law enforcement agency of the Australian Government responsible for investigating Crime in Australia, crime and protecting the national security of the Commonwealth ...
have confirmed they have purchased the devices. * : Azerbaijan police * * : Multiple police departments * : China Coast Guard * : Used first time on March 18, 2017, by the
Police of the Czech Republic The Police of the Czech Republic () is the national agency in the field of law enforcement in the Czech Republic. It was established on 15 July 1991 under the jurisdiction of the Ministry of the Interior (Czech Republic), Ministry of the Interior ...
* * * * :
Police Tactical Unit A police tactical unit (PTU) is a specialized police unit trained and equipped to handle situations that are beyond the capabilities of ordinary law enforcement units because of the level of violence (or risk of violence) involved. The tasks of a ...
and Police Negotiation Cadre (PNC) of the
Hong Kong Police Force The Hong Kong Police Force (HKPF) is the primary law enforcement, investigative agency, and largest Hong Kong Disciplined Services, disciplined service under the Security Bureau (Hong Kong), Security Bureau of Hong Kong. Pursuant to the one c ...
* :
Delhi Police The Delhi Police (DP) is the law enforcement agency for the National Capital Territory of Delhi. Delhi Police falls under the jurisdiction of the Ministry of Home Affairs, Government of India. In 2024, the sanctioned strength of Delhi Police w ...
* : Ministry of Defense,
Israel Police The Israel Police (; ) is the civilian police force of Israel. As with most other police forces in the world, its duties include crime fighting, traffic control, maintaining public safety, and counter-terrorism. It is under the jurisdiction o ...
* * : New Zealand Police * :
Norwegian Navy The Royal Norwegian Navy () is the branch of the Norwegian Armed Forces responsible for naval operations of Norway, including those of the Norwegian Coast Guard. , the Royal Norwegian Navy consists of approximately 3,700 personnel (9,450 in mob ...
onboard Fridtjof Nansen-class frigates * :
Philippine National Police The Philippine National Police (PNP; ) is the national police force of the Philippines. Its national headquarters is located at Camp Crame in Bagong Lipunan ng Crame, Quezon City. Currently, it has approximately 228,000 personnel to police a pop ...
,
Philippine Coast Guard The Philippine Coast Guard (PCG; ) is the third armed uniformed service of the country attached to the Philippines' Department of Transportation, tasked primarily with enforcing laws within Philippine waters, conducting maritime security ope ...
* : Polish Police (acquired, but legal reasons were preventing its usage) * : Used first time on June 7, 2015, by
Jandarmeria Română The ''Jandarmeria Română'' () is the national Gendarmerie force of Romania, tasked with high-risk and specialized law enforcement duties. It is one of the two main police forces in Romania (the other being the Romanian Police - a civilian fo ...
* : Used by the
Singapore Armed Forces The Singapore Armed Forces (SAF) are the military of the Republic of Singapore, responsible for protecting and defending the security interests and the sovereignty of the country. A component of the Ministry of Defence (Singapore), Ministry of D ...
* : Used by the
South African Police Service The South African Police Service (SAPS) is the national police force of the Republic of South Africa. Its 1,154 police stations in South Africa are divided according to the Provinces of South Africa, provincial borders, and a Provincial Commis ...
* : Reported use by Catalan Police * :
Swedish Navy The Swedish Navy () is the maritime service branch of the Swedish Armed Forces. It is composed of surface and submarine naval units – the Fleet (), formally sometimes referred to as the Royal Navy () – as well as marine units, the Amph ...
* * : Used by the
Turkish Naval Forces The Turkish Naval Forces (), or Turkish Navy (), is the naval warfare service branch of the TAF. The modern naval traditions and customs of the Turkish Navy can be traced back to 10 July 1920, when it was established as the ''Directorate o ...
* :
Ministry of Defence A ministry of defence or defense (see American and British English spelling differences#-ce.2C -se, spelling differences), also known as a department of defence or defense, is the part of a government responsible for matters of defence and Mi ...
* : Multiple police departments,
US Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...
, US Coast Guard and
US Army The United States Army (USA) is the primary land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of the United Stat ...
* : Being used on-board DN-2000-class ships of the Vietnam Coast Guard's fleet.


See also

*
Acoustics Acoustics is a branch of physics that deals with the study of mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician ...
*
Megaphone A megaphone, speaking trumpet, bullhorn, blowhorn, or loudhailer is usually a portable or hand-held, cone-shaped horn (acoustic), acoustic horn used to amplifier, amplify a person's voice or other sounds and direct it in a given direction. ...


References


External links

{{Commons category Riot control weapons Non-lethal weapons Military equipment introduced in the 2000s