From concealed installations in hotels to live streams sold online, a black market exploited by criminals is endangering personal privacy, exposing victims to a vast audience.

Audio takes a back seat in many security systems because audio captured from a surveillance camera can have a different impact on the privacy of those being monitored. Audio surveillance is therefore ...

Emma Fierberg: I'm looking for the camera. Is it on the doorknob? Michelle Yan: It's not on the doorknob. Michelle Yan: So, we got our hands on some spy gear from Amazon. (These are so tiny).