I am the pilot who had the emergency and was rolling out toward you on 7L/25R. I am sure your instructor is giving you plenty of feedback on this one - but as a flight instructor for 37 years let me reiterate what he is probably telling you. Even though you have been cleared to land (or take-off, or turn, or anything else by ATC), you are still responsible for many things, including aircraft avoidance. I am glad to hear you were a student pilot, because that means your concentration was probably on flying (speed, altitude, coordinated turn) and I suspect you simply did not hear the radio. Sounds dumb, but I have had many students ignore loud things (gear horns, stall horns) when they are concentrating hard. I think you were not really NORDO, because you heard the instructions to use the other runway, etc. It does not really matter in any case, I think this is a good lesson for you to remember than no matter what else is going on - you need to look around and ahead even if you think everything is cleared for you. For what it is worth, my wife was yelling at me "he's still going to land!" multiple times but I was in a sever slip to landing and there was no way with my engine I was going to go around - I was ready to bail into the infield if necessary depending on what happened. OK - enough of that, on the plus side - you did a really, really good job going around for a student pilot. It looked to me like you were very near to stall speed as you were struggling to gain altitude. That was a very good job. I suspect you and my wife were far more rattled than I was (I was too busy trying to land again than to worry about much else). Good luck in getting your license and if I see you around the airport I'll by you a drink (after you fly - of course.)