Developers can appear very unproductive at times, sitting staring at the screen with our headphones on and very little in the way of keyboard clackety-tap. This however is when we are doing our thinking, when we are building up, adding to and rearranging the mental model of how our code will work. This is the biggest and hardest part of development. Imagine how it feels to have that interrupted at random by a telephone call or somebody walking over to talk to you. It’s horrible.

http://thetomorrowlab.com/2015/01/why-developers-hate-being-interrupted/