I applied online and also with a recruiter. Standard process - set up a phone screening a couple of weeks out. The interviewer was definitely not the one listed in the email (possibly last minute replacement) and he must have been sitting in an open area at first; I had to mention the heavy background noise twice (I could hear voices, though not exact words, before he made his first adjustment). Because of the level I was asked a lot of platform (iOS) questions, primarily around threading, in a rapid-fire manner. I know I did well on the algorithms (saw a more complicated version of one of them before) and even had time at the end to discuss, but not code, a variant on one question. However, I supposedly did not answer the platform/threading questions fast enough so the hiring committee (for a phone screen) declined to invite me for an onsite. Very likely I would not have moved on regardless of the background noise, but it didn't help.