Is it legal in CA to record a conversation without a person's knowledge (i.e., in a store along with video)?

I know of a convenience store in CA where the owners have video surveillance cameras throughout the store. The system also is recording audio and it is known that the system can "zoom in" on low-level conversations. Doesn't the owner have to post a sign notifying customers that audio recording is taking place? Also, what is the recourse for taking legal action? Can someone simply report this to the local police department? Or is there some other agency they would complain to?