Yeah, I work in an office with an open floor plan and have a lot of trouble with this. It would be one thing if I could just put in ear plugs and block it all out, but I spend a lot of time on the phone with clients, so that's not really an option.
I now have a coworker who is so loud I almost feel like he must be doing it for attention. He used to just plop a radio on his desk and turn it on and I managed to get him to start wearing ear buds instead. (I told him a client had complained about the background noise when I was on the phone with her, which was true). But, he still hums and stomps along to the music, which drives me crazy.
He takes his lunch at his desk and he even chews so loudly, I can't concentrate. I know that makes it sound like I just have really sensitive hearing, but I swear it's true. I've never watched him eat (we're in cubicles, so I can't actually see him), but I know it's with his mouth open and I can hear him smacking his lips, making these weird "Hmm, yeah, that's so good" comments under his breath, like he's talking to a woman instead of a piece of leftover lasagna, etc. I swear one of these days, I'm going to record his lunch break and put it on YouTube or something.