This is a bu11$#it answer below.

In aircraft use, the microphone is open on both sides in the holder. Noise
coming in one side is cancelled by noise coming in the other side (i.e. they
both hit the microphone in phase and push and pull the element equally,
cancelling out the noise response). How much they cancel is a function of
how well the mic holder is engineered and tested.

Your voice hits the mic on one side only, and is thus imbalanced. It is
this imbalanced output that you get to use for mic audio.

Again, the ONLY thing that cancels noise is how well the mechanical/acoustic
engineer designed the mic housing to cancel the noise.

Jim


Classically, a noise cancellig mic is two microphones placed either back
to
back or a radically different distances from the mouth of the person
speaking. For example, a mic pickup placed one inch from the speakers
mouth, and the second at three inches, so that the evels are radically
different. The two microphones are then wired out of phase, so that the
background noise, which is assumed to reach both microphones equally, will
be cancelled. In addition, sound outside the classic "telephone" band of
300Hz to 2500Hz can be filtered out for a further benefit in
intelligibility.