How Do You Concentrate on Your Writing?

To all my fellow writers out there how do you concentrate on your writing?

What puts you in that focused frame of mind?

For me I need quiet.  I cannot concentrate in those scenes enough to describe them if I am next to some one who is also "working" but constantly chatting.  I can do research with the occasional chatter; however, the actual writing portion requires more focus for me.  It is a task in of itself.  It is similar to meditation because generally I am very calm if during my writing time I went some where--that is ideas were expanded, characters were taking more form, understanding what I am writing more takes place.  All this needs quiet.  I am pretty good at concentrating in a library, but not near loud talkers, cell phone talkers, and screaming children or infants.  I am forced to move location in those situations if the offending noise does not cease, or my work will suffer.    

On the flip-side I challenge myself and sometimes experiment to see if I can learn to tune out varying levels of noise.  But nothing is quite like silence.  It is almost as if the environmental noise affects the sound waves of the internal noise.  High-pitch sound of a baby crying makes me angry that the initial reaction is to want to smash something which could be that I'm responding to the same emotional frequency is my estimation.

Civility and the understanding that babies are helpless, and they don't know they are in the library revert to humor with the calming joke of bouncer escorts baby out of library because "You did not use your quiet voice."