Last June, Clinton Clad-Johnson joined his fellow stressed-out UCLA students, peeled off his pants and participated in a beloved tradition: the "undie run."
"Everybody knows that finals season can be very stressful, right? So everybody goes running, kind of half naked in their underwear," he said.
But this undie run was different.
As Clad-Johnson and other students were sprinting through campus, they heard an incredibly loud noise.
"It was kind of reminiscent of the sounds you hear in war movies," he said.
Campus police had turned on a Long Range Acoustic Device - the same type of sirens used in Iraq to break up crowds with ear-splitting tones.
"The sound was intimidating and it really made me back off," he said. "It shuts down your mind and it pierces your ears."
As students ran away, Clad-Johnson took out his camera and filmed it.
About 30 seconds into the video Clad-Johnson yelled at the police: "You're using sound weapons!"
'An improved megaphone'
Since 2014, all ten University of California campuses have been equipped with the devices, called LRADs for short. They double as a powerful megaphone and UC San Francisco, Berkeley and UCLA have all used them to make announcements.
"The LRAD is an improved megaphone and it allows us to be heard over greater distances, with more clarity than the average megaphone or public address system that’s in a car," said Lieutenant Mark Littlestone of the UCLA Police.
The device could come in handy during an earthquake or an active shooter situation, he added, when "a handheld megaphone just doesn't cut it."
Of the ten campuses, only UCLA has used the LRAD's siren to overpower crowds, according to university officials.
All three instances in which UCLA officials blared the powerful siren were in response to undie runs - in March, June and December 2014.
The UC system's decision to purchase the devices comes as police on and off campus have come under criticism for the acquisition of military style weapons.
The Los Angeles Unified School District received an armored vehicle and grenade launchers from the military as part of its program to provide surplus materials to local law enforcement agencies, but the school system returned both last year after a public outcry.
The device at UCLA can blast out noise at 137 decibels, according to its manufacturer. That's louder than a jackhammer, rock concert, or ambulance siren.
Sounds that loud can harm hearing in just a few seconds.
"That's called acoustic trauma," said Dr. Rick Friedman, who studies hearing loss at USC's Keck School of Medicine. "The inner ear, when hit with a sound approaching 140 decibels and above, gets really rocked."
In Clad-Johnson's video, the UCLA police use the tone for more than 25 seconds—five times longer than the maximum the university's guidelines allow for, which is 2 - 5 seconds.
Littlestone, the UCLA police official, acknowledged the use of the LRAD in the video "does appear to be in violation of our guidelines."
In an email, he said that the department would "take a look at it and address it, either as a training issue or a need to revisit the guidelines."
"Even tactically it didn’t make much sense" to use the device during an undie run, said Robert B. Weide, who teaches criminology at Cal State Los Angeles. "They were using it to clear a space between two buildings. And then what? The students run around the other side of the building?"
Beyond that, he criticized the use of that equipment by campus police at all.
"It's this pattern of them employing what is a very serious tool that should be employed in dire circumstances. And instead they're employing it to chase college kids around campus," he said. "It's absurd."
LRADs were developed in response to the attack on the USS Cole in 2000, and are manufactured by the San Diego-based LRAD corporation. The company's promotional materials show Marines using them "to transmit warnings and direction in Arabic."
LRADs also have non-military applications—like scaring birds away from wind turbines.
They were used at protests surrounding the G-20 Summit in Pittsburgh in 2009. One woman exposed to the sonic blast from about 100 feet away sued, saying it permanently damaged her hearing. Police settled the case for $72,000.
In August, an ear-splitting LRAD blast drove away protestors in Ferguson, Missouri. In response to that incident, Amnesty International released a report that said "LRADs can pose serious health risks which range from temporary pain, loss of balance and eardrum rupture, to permanent hearing damage."
"Do we really want to bring those types of things home?" asked Clad-Johnson, the student who filmed its use during the undie run at UCLA.
In response to a records request, the LAPD said it does not have an LRAD. The Los Angeles County Sheriff's Department does have an LRAD capable of sounds even louder than the device at UCLA. (KPCC obtained the Sheriff's policy on LRAD use, you can read that here).
UCLA's policy on LRAD use: