Though some on the market may be available with the ability to record audio, these cameras should not be used due to the illegality of the recordings they produce.
The use of hidden cameras is generally permitted under UK law, if used in a legal manner and towards legitimate ends.
This latter subgenre of unwitting participants began in the 1940s with Allen Funt's Candid Microphone theatrical short films.
In 1996 the genre was given an overhaul by Travis Draft who introduced the glasses cam with his show Buzzkill.
In the United States, nanny cams are legal although most are sold without audio capabilities, since it is prohibited to intercept audio communications surreptitiously.
US Code Title 18, Chapter 119, Section 2512 prohibits the interception of oral communication by "surreptitious manner" such as a hidden camera, and so most nanny cams are not available with audio recording.
A wireless spy cam may transmit video online so that it can be viewed remotely or it may transmit video to a receiver that records to an internal memory card or DVR or may allow live viewing through a monitor.