Bus commuters in cities across the US have likely grown used to surveillance cameras recording their every move, but may not realize that microphones are also becoming more prevalent. An increasing number of transit companies are investing in security systems capable of recording passenger conversations, and in doing so have raised significant privacy concerns. Wired is today reporting on one popular choice, the RoadRecorder 7000, which combines both audio and video recording in one package.

Fears of eavesdropping have surrounded this particular IP-connected system since it's remotely accessible via the web. Typically between four and six camera/mic combinations are installed in each bus, giving transit authorities the ability to closely monitor passengers seated virtually anywhere. In one instance, Oregon officials even asked for microphones capable of separating individual conversations while cutting out wind, traffic noise, and other environmental distractions.

From the perspective of bus companies, these advanced surveillance systems offer passengers (and drivers) a greater level of security. Yet they've met fierce resistance from civil liberty and privacy-minded groups who insist such recordings violate wiretapping laws. According to Wired, similar microphone-based security systems are currently in use in seven cities in the US, a number destined to climb in the months ahead.