Audio surveillance devices are being installed on city busses, under the title of "safety".

At least eight US cities are quietly installing sophisticated audio surveillance systems on public buses, raising concerns about creeping government intrusion on citizens’ privacy and civil liberties.

The Daily reports that city officials are pressing ahead with plans to install systems that will allow authorities to listen and record riders’ private conversations in addition to the video footage already being recorded by existing devices. The audio systems will be linked to the video, allowing transit authorities or police to monitor the private conversations of every single bus passenger.

City officials and transit agencies claim that audio surveillance will allow them to better ensure passenger safety, solve crimes and resolve complaints. But civil liberties advocates are alarmed by what they see as a blatant and shocking violation of privacy.

“This is very shocking,” University of Pennsylvania privacy law expert Anita Allen told The Daily. “It’s a little beyond what we’re accustomed to. The adding of the audio seems more sensitive.”