Looking for advice on how to approach an insecure coworker (he is intimidated by my abilities) who talks loud and often in our open office environment (the cubicle walls do not help with noise). He often yells out, "Hey X, are you there?" Often X is not there, so my thoughts are interrupted unnecessarily. I keep meaning to say something when it happens to let him know it is quite disruptive and could he please go to X's cube (10 feet away) to converse. Secondly, when he is listening to someone on the phone he constantly talks "Yeah", "OK", etc. or says "Mmmhmmm" or "Ooooohhhh" to the point where I cannot concentrate. My options are to leave and go work in a more public and less secure area-not always an option (plus, I can't be at my desk with the things I need), put in ear buds and play music or rain recordings very loud to mostly drown him out. I have also recently brought up working from home a few hours a week so that I can have a quiet environment for the tasks needing heavier concentration. Additionally, I spent $350 on good noise cancelling headphones (the $60 ones I tried didn't fit). There isn't really room for me to move elsewhere in the company. I know I need to address these things, though the last time I noted that I would have scheduled an appointment for a different day had I known he would be out, his response was "Thank you for letting me know I failed to put it on the appointment calendar. It's there now." He added it after the appointment had already happened. Thoughts about how to approach an insecure and angry (I'm leaving a lot of info out) almost 50 year old man?