car problem

There's a wind-up clock in the back seat!

Could you provide just a tiny hint of what it sounds like or where it's coming from? We can't hear it over the computer. Does the engine have to be running to hear it, or do you just have to turn on the ignition switch? Does the car have to be moving? Does the sound change when you change the heater fan speed? Does the noise only occur when the windshield wipers are running? How often do you hear it? Any clue will be helpful.