I have been in this situation before and definitely fully appreciate just how annoying and distracting it can be. I think if you've never been stuck working next to someone who does this, it's hard to understand how much it impacts your entire day. There was a guy who shared a cubicle wall with me in my job right out of college who would chew so loudly that I could hear every single thing going on in his mouth. And it wasn't even just during lunch time that I had to deal with it. He would chew ice non stop all day long. I mean, constantly. I have no idea how he even had teeth left! I never did figure out what to do about it other than shooting him really dirty glances and making comments to my friend across from me about how I was having a hard time hearing the person I was talking to on the phone. If I had had the guts to do it, I think I would have liked to have taken him aside one day and just very kindly explain to him that a lot of us in the office were bothered by how loud his mouth habits were. But I never did work up the courage and I left that job anyway... Good luck with whatever you end up doing!