For me it is an officemate talking loudly on the phone that is really distracting. Last year a guy in the office would have long, loud, sometimes heated conversations on the phone with me and 2 other people sitting in the office. Apparently, he was also a preacher and his cell phone ringtone was "Our God is an Awesome God" and he was one of those people that when he made a call on his desk phone he would put it on speaker phone, dial, let it ring, and then pick up the phone. That's when I brought in my over the ear hearing protectors.

Luckily, he got a different job but oddly, the person who sat behind me moved to his desk and now she has started making lots of calls. Maybe that desk is cursed or something?