AUSTIN (KXAN) — As Austin city leaders are poised to ban the use of beanbag rounds and tear gas against protesters, police have another way to disperse crowds.

A photo taken and shared online this week shows officers standing on top of the Austin Police Department’s headquarters building, next to what looks like a speaker.

Robert Auld, who has worked as an audio engineer for decades, looked at the picture and identified it as a “long range acoustic device,” also known as an LRAD.

A photo shows what appears to be long range acoustic device
(LRAD) mounted on a tripod on top of APD headquarters.

Invented for communication between naval ships, he told KXAN that the devices have been integrated into police departments in the last 20 years.

The idea of LRADs is to peacefully disperse crowds with a loud alarm.

Auld says all LRAD models can reach at least 130 decibels (dB).

“If you have a device that’s going at 143 decibels and you’re 100 feet away, it will still be around 128 decibels, which is very loud,” he said. “It would cause you to put your hands over your ears and want to leave the area.”

For perspective, Auld says a normal conversation between two people reaches 60 to 70 decibels, a heavy metal concert can reach 120 decibels, and the threshold for pain in the ears is 130 decibels.

When you’re getting up to 120, 130 decibels, exposure of just a couple minutes could cause hearing damage, Auld said.

“Being next to a jet engine is 140 decibels, that could damage your hearing within seconds,” he added.

Auld mentioned that LRADs are directional and moving off to the side or wearing earplugs could prevent or reduce damage.

“If you move off 45 degrees, you could get out of the line of fire,” he said.

Austin police told KXAN the department has an LRAD 450XL model, which it used to direct protesters off Interstate 35 on Saturday night.

Although [the LRAD] has other capabilities, we use it as a public announcement system,” a department spokesperson told us. “The only time the device is used is to notify individuals who are breaking the law.”

She added that we would need to contact the manufacturer to know more about how how loud the device can get.

In the latest version of APD’s policy manual, the use of long range acoustic devices are not mentioned. There is a section for “kinetic energy projectiles,” which include bean bag rounds.

These rounds, known to law enforcement as “less than lethal,” have been the subject of intense scrutiny after they were used to shoot and seriously injure two young men during protests late last month.

Last week, Austin Police Chief Brian Manley said the department would no longer use bean bag rounds in crowd situations, and city council members expect to solidify that as an official policy this Thursday.

Controversy over LRADs

In 2012, the city of Pittsburgh settled a lawsuit with a woman who claimed to have suffered permanent hearing loss after Pittsburgh Police used the devices during protests in 2009.

The original complaint says the plaintiff felt “immediate pain in her ears, and she became nauseous and dizzy.”

Court documents say “she was forced to sit down and was unable to walk.”

The American Civil Liberties Union (ACLU) calls LRADs “acoustic weapons” and recommends not using them until concerns about their potential to cause hearing loss are addressed.

In New York City, six plaintiffs filed a federal lawsuit against the New York City Police Department for its use of an LRAD on Manhattan protesters in 2014.

The plaintiffs were part of a protest following a grand jury’s decision not to indict an officer involved in the arrest that led to Eric Garner’s death that year, according to court documents. Garner died in Staten Island after an NYPD officer placed him in a choke hold while arresting him for selling untaxed cigarettes.

Directions on the LRAD used in the New York case warn not to get closer than 10 meters to the device’s 30-degree cone of projection, according to the lawsuit. The plaintiff’s said the NYPD used the device from a “car width away,” according to the case filed in 2016 in the Southern District of New York.

One plaintiff said she heard a “whirring siren” and almost immediately felt migraine pain and “woozy.” Another plaintiff said he experienced a migraine that lasted five days after the LRAD exposure and later developed tinnitus and vertigo. Several of the plaintiffs said the LRAD emitted the loudest sound they had ever heard, and all of them had lingering hearing problems afterward, according to the suit.

The NYPD denied essentially every allegation in the lawsuit, and the case remains pending.

APD tells us placing the the LRAD on top of its building was done to ensure there was plenty of space between the device and protesters.