A "Beep" when i turn off the car

No idea how to explain this. Every now and then when I turn off the ignition to my 2007 HHR, I hear a very tiny electronic “beep” tone. It sounds like a chirp or something. I cant tell where it comes from but when I do hear it, it happens immediately when I turn the ignition off. Any ideas???

could be the anti theft buzzer in the radio. just letting you know to remove the detachable face.

have you read the owners manual? and the sound system manual? look through them. you will probably find the answer there.