There are recording cameras that also record sound. There was rather a controversy a few years back about such a system in what I believe was a Dunkin' Donuts (though I may be wrong about the place).
The basic rule as I understand it is that when you are in a public place you have no reasonable expectation of privacy. It is not illegal to record you in a public place without your permission. It IS illegal to do so in a situation wherein you have a reasonable expectation of privacy. For example, you have the right to have a private conversation in your home, on your telephone or on your private property. But I can be walking down the street recording a note to myself and you might blunder by discussing your latest murder victim. In that case, unless I misunderstand it, that recording is both legal and admissable as evidence.