Essentially this is what happens. If you observe, the sound is created by vibrating the motors of the Mavic. It seems to have a pattern. Lower right, upper left, lower left, upper right. If you put your fingers on the motors, you can really feel them vibrate. As for smart LED it's essentially the same as ESC beeping but without the noise and the rear flashing red. It's quite loud actually, and to start it, requires your device to be connected to the RC and the RC connected to the Mavic. I would imagine if you are in the area where the drone landed and reconnect the sound can be activated to find it in hard to find locations.