the reason i even noticed this almost invisible feature is i have an LG envy hooked up to another line since i had to add a line to upgrade to droid from omnia. i was on the envy talking to my dad and he told me how loud my tv was in the background (somthing he had said a lot in the past but had'nt since i got the droid) so i said i'll call you right back and called him from the droid, to my pleasant suprise he could no longer hear the tv even when i cranked up the volume!!! i then tested it, in addition to the tv and radio it "cancels" the sound of the toilet, sink, shower, blender, electric can opener, exc.