Originally Posted by KlaymenDK

I just tested this, and it seems to be incorrect.
I recorded a video in a quiet room and supplied some "noise" (known to some as "80's music" ) through a set of earplugs. The video only contained audio when I held an earplug near the bottom phone mic; I heard no difference when I held an earplug near both holes, so I don't think that (in the Galaxy, at least) there's any active noise cancellation.

I could be wrong, though!