Campbell headshot

Chris Campbell

A newly introduced bill in the Indiana State House aims to ban the use of acoustic hailing devices over 150 decibels by law enforcement to control crowds within 100 feet.

Chris Campbell, state representative for Indiana’s 26th district, authored the bill.

Acoustic hailing devices are loudspeakers designed to concentrate sound and project it long distances, said Alex Francis, an associate professor of speech, language and hearing sciences at Purdue who recommended the bill. They were originally designed to allow Naval ships to communicate with nearby vessels.

Francis said he reached out to Campbell, a neighbor and fellow audiologist, after he helped write a statement on acoustic hailing devices for the Acoustical Society of America as a member of the public policy board.

His attention to this issue, he said, sparked after reading a New York Times article published in 2014 about reports of dizziness from protesters at a demonstration following the acquittal of the police officer that killed Eric Garner.

“And I guess it (became a big issue) with the big demonstrations in response to the murder of George Floyd this past summer where it really came out that these are in widespread use now,” he said.

Campbell noted a nationwide initiative, including a statement from the Academy of Doctors of Audiology that calls for an altogether ban on the weaponized use of long range acoustic devices, to learn more about and regulate the use of AHDs, in prompting her to author the bill.

Campbell also co-authored the Byron Ratcliffe Sr. Racial Profiling Act, which seeks to prevent law enforcement from racial profiling.

It would require law-enforcement agencies to create detailed definitions of racial profiling, collect data on stops officers make and conduct diversity training. The agencies would also have to submit reports documenting complaints about racism to the attorney general.

Some law enforcement agencies adopted AHDs for crowd control, and audiology experts have raised concerns about their dangers in civilian settings.

“Police have had bullhorns for decades now,” Francis said. “So this seemed like a logical extension. The only thing is that these have the capacity to be so much louder at the point of the target.”

The Purdue University and West Lafayette Police departments were unsure about what constitutes an acoustic hailing device. Lt. Michael Brewer of the WLPD said the closest their department has to AHDs are bullhorns and car sirens, but that in his 17 years on the force they were never used against crowds.

Francis said while bullhorns and AHDs serve a similar purpose, there are two main differences.

This first, Francis said, is that bullhorns don’t focus sound, they radiate it. It is almost as loud for the user as the target.

AHDs, on the other hand, concentrate a beam of sound to the target. Other people nearby can hear the sound, but it won’t be nearly as intense as it is for people on the receiving end of the beam.

“It’s much more muffled if you’re not in the beam of the AHD,” Francis said. “And that’s part of what makes them so dangerous. Somebody could accidentally walk across that beam and suddenly be deafened.”

Secondly, AHDs get much louder than bullhorns. While the sound from traditional loudspeakers gets quieter the further it travels, AHDs were designed to emit beams that retain their intensity over long distances.

The effects of this intense sound can be damaging.

The bill focuses on loudspeakers that reach 150 decibels or higher. One hundred fifty decibels is the equivalent of standing near a jet at takeoff and is enough to rupture the eardrum, according to the Centers for Disease Control and Prevention.

“The intent is not to cause damage, but to address crowd control,” Campbell said. “However, this would greatly harm an individual to be within 100 feet of that device being activated.”

The Occupational and Safety Health Administration measures how much noise a person can handle on a jobsite before sustaining serious auditory damage, like an eardrum rupture. A person can withstand 32 hours of 80-decibel noise without harm, 1.8 minutes of 130-decibel noise, and three seconds of 150-decibel noise. The noise level should never surpass 140 decibels, the threshold of pain, according to the OSHA website.

“(150 decibels) is essentially instantaneous deafness, or at least hearing impairment,” Francis said. “The problem is if you deafen somebody, even if you only give them hearing impairment, you’ve changed their life forever. Your inner ear is not just for hearing, but part of your inner ear is also for balance, and that can also be damaged by high levels of sound.”

The nationwide initiative is shaped in the form of bills in the New York State Assembly, New York State Senate and Kentucky General Assembly limiting the use of AHDs until there is more research available on them. There is also a lawsuit in New York Federal Court challenging the constitutionality of AHDs by alleging the use of excessive force, according to reporting by the New York Times.

AHDs were developed after the suicide attack of the U.S.S. Cole in Yemen by an al-Qaida speedboat in 2000, Francis said. At the time, there was no way for the crew of the U.S.S. Cole to communicate with the suspicious speedboat because it didn’t have a compatible radio. AHDs allow verbal communication across long distances by concentrating sound waves like laser beams.

As AHD technology became more compact, it transitioned into uses outside the naval sector. For example, Mountain View, California, uses AHDs for their avalanche warning systems to contact hikers quickly. They’re also small enough to carry around now — making them much more portable than the boat-mounted counterparts.

“These are devices that were developed for a very specific military purpose, and they have a really important role to play there, potentially,” Francis said. “Where I get concerned is as they start to be used not just as warning systems … but actually to use that sound as a weapon. And if that’s going to be done, I think we need a much better understanding of how to do that in a way that we are not inflicting permanent harm on people.”

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