Hundreds of schools in the U.S. have begun using aggression detection surveillance technology in order to monitor students, but a ProPublica analysis found that the software may not be entirely reliable. Louroe Electronics sells microphones using the detection technology from Dutch company Sound Intelligence and claims the software enables security officers to “engage antagonistic individuals immediately, resolving the conflict before it turns into physical violence.” School officials have been using the devices in hopes of preventing everything from underage smoking to mass shootings. But a ProPublica/Wired magazine analysis of the technology reportedly found the aggression detector sometimes equated coughing with aggression. The detector also cannot take words or meaning into account, meaning a loud joke—like a 1994 YouTube clip of comedian Gilbert Gottfried, in one case—could set it off. Other experts have disputed the premise that verbal aggression precedes school violence in the first place. “It’s not clear it’s solving the right problem. And it’s not clear it’s solving it with the right tools,” a University of Utah computer-science professor told ProPublica. “I can’t imagine when it would be useful, honestly,” an assistant professor of criminology and criminal justice at Hamline University told the news outlet.