I *heard* so may well be wrong, but they will be introducing noise cancelling, that at a press of a button, will uncancel that function. So, ur on the tube listening to your music, and on comes an announcement, you press a button and you can now here, press it again, and back to music.
IEMs are better than any noise cancelling phone as they create a seal in your ear canal. No idea if the PTH is any good. Search for reviews on head-fi or the one here