Your Train Could Be Listening to Every Word You Say by David Z. Morris @FortuneMagazine April 16, 2016, 12:52 PM EDT E-mail Tweet Facebook Linkedin Share icons Adding another uncomfortable layer to the ongoing debate about security and privacy, NPR reports that a growing number of transit systems around the U.S. aren’t just using security cameras, but also recording audio of riders. New Jersey Transit records audio and video on light rail trains running between Trenton and Camden. Audio recording is in place on many other public buses and train systems nationwide, including some run by the Maryland Transit Administration. New Jersey Transit and other authorities have said the systems are part of an effort to deter and defend against both criminal and terrorist acts. Get Data Sheet, Fortune’s technology newsletter. Audio can reveal important information like names, or the circumstances surrounding an altercation or crime on transit. Funding for the systems is often provided by grants from the Department of Homeland Security. But even for those used to the idea of security cameras keeping an eye on them, audio recording triggers a sense of unease. “It’s too Orwellian for me,” a New Jersey rider told NPR. “It reeks of Big Brother.” A spokesman for the Maryland Transit Administration was quick to point out that vast majority of audio recordings are never listened to by anyone. The MTA archives them for 30 days, then deletes them if they’re not needed to investigate a specific incident. For more on privacy vs. security, watch: Other agencies have been less forthcoming about their practices, though, with an interim director of New Jersey Transit declining to provide the information to the Associated Press. The ACLU of New Jersey has expressed concern over the practice, saying that conversations on buses and trains may be legally protected by a ‘reasonable expectation of privacy’ standard. They have not yet formally challenged the practice.