As a counterpoint, I work on my own now, having worked in open plan offices for years, and I find it hard to concentrate because I feel lonely. My ideal office size would be somewhere between 5 and 10 people in a room all working on the same project. You just need a rule that you must leave the room to make phone calls that last longer than a couple of minutes, especially if you have an annoying voice or telephone manner or there is some emotional content to the call. With this setup there should not be to much background noise and you can ask a colleague a question when it suits you as long as you are respectful and don't disturb them if they are 'in the zone'. There is research that supports the 5-10 people sharing a office theory, I think done in the Netherlands in the 70's but I can't find it now. I can't help but think that there is a good reason related to camaraderie and teamwork that around 8 people just so happens to be the smallest organisational unit in the army, a principal the Romans discovered 2000 years ago.
