Ok, just got my hands on a P770MP pioneer deck.

One feature some Pioneers have of late is:

Automatic Sound Levelizer (ASL):
During driving, road noise in the car changes according to the driving speed and road conditions. The Automatic Sound Levelizer monitors the road noise and automatically increases the unit's volume level, if the road noise becomes greater. The sensitivity of this feature can be set to one of five levels (low, mid-low, mid, mid-high, or high).

My question is, where the hell is the microphone in this *****?

I know it works, but road noise isnt really what its best for, its best for opening the windows at high speeds and not having to touch the volume. But I would like to know where its listening!?