LRAD used on protestors in Minneapolis

by Halimat Olunlade, Social Media Manager

Photo credit: Myotus

At the end of January, the Minnesota State Patrol deployed a long-range acoustic device (LRAD) against protesters gathered outside a hotel believed to be housing the head of U.S. Border Patrol. While authorities maintained the device was only used to deliver commands to disperse, the incident raises urgent questions about the weaponization of sound against civilians.

LRADs were originally developed for the U.S. Navy following the 2000 bombing of the USS Cole in Yemen. The technology was designed to allow naval personnel to contact approaching vessels from over 3,000 meters away when radio communications failed.

Unlike conventional loudspeakers, LRADs focus sound into an intense, directional beam, producing noise so powerful that it “pushes you back”, resembling the booming “voice of God,” a retired U.S. Marine Corps colonel told CBS Minnesota.

But what makes these devices alarming from a hearing health perspective is their potential to reach 135 to 160 decibels (dB). To put that in context, the Occupational Safety and Health Administration requires hearing protection for any sound exposure over 90 dB. The human ear typically begins to experience sound as pain at around 120 dB.

At full power, LRADs can cause immediate and permanent damage. According to a warning issued by the American Speech-Language-Hearing Association (ASHA), exposure to LRADs “is capable of causing not only permanent hearing loss but also migraine, balance, and other auditory symptoms.” ASHA notes that “the decibel level of speech presented through LRADs is unsafe, capable of causing temporary and permanent hearing loss for those in front of, behind, or on the periphery of the device.”

The Acoustical Society of America (ASA) issued a similar policy statement on acoustic hailing devices (AHDs) in July 2020, recognizing the potential risks to human health posed by AHDs and strongly urging law enforcement agencies to develop and adhere to strict safety guidelines for LRADs. Most significantly, the ASA recommends that law enforcement agencies do not use AHDs for crowd-control purposes without safeguards.

Since their introduction for military use in 2003, LRADs have spread to police departments across the country. They've been deployed at protests in New York City, Pittsburgh, Oakland, Portland, Seattle, Phoenix and now Minneapolis. While law enforcement typically characterizes these devices as communication tools, their use in “alert mode” — which emits a piercing, painful tone — transforms them into what civil liberties organizations call “sound cannons” or sonic weapons.

In 2021, New York City settled a lawsuit after protesters alleged the NYPD's use of an LRAD caused migraines, sinus pain, dizziness and ear ringing. As part of the settlement, police were banned from using the alert tone feature.

While the immediate concern is harm to protesters and bystanders, the proliferation of high-intensity acoustic devices raises broader questions about noise as a tool of control. The same technology used in LRADs can be benign, such as in museums where “audio spotlight” systems deliver sound to certain listeners without headphones. But as these technologies become more powerful and widespread, the line between communication and coercion grows increasingly thin.

Minnesota State Patrol says it only used the LRAD to broadcast commands. But even voice amplification through these devices can cause harm at close range. And without independent verification, how can the public know what sound levels were actually deployed?

More fundamentally, the question is whether military-grade acoustic technology should be used against American civilians at all. The ASA — not a political organization, but a scientific one founded in 1929 — has called for suspension of these devices for crowd control. When the nation's leading acoustics experts say we need to stop and study the harms, shouldn't we listen?