I have to do any high-concentration work at night as well, and have likewise found that successfully finding some level of silence in life makes me more sensitive to noise...

In my case I've made a concerted effort to remove all aural advertising from my life -- this is rather easier nowadays, when it's trivial to watch videos and listen to music without ever consuming broadcast media.

But now when I do accidentally encounter normal TV/radio, it's amazingly grating and completely invades my head. I was in an airport in the US with TVs everywhere, and it was like trying to do work next to a fistfight. Commercial jingles pop into my head and stay there, when I'm unlucky enough to encounter them.

I think the problem is compounded by the fact that modern advertising is calculated to break through the normal deluge of attention-seeking noise that people are drenched in, so if you are not, in fact, already swimming in other noise, the sudden bursts are overwhelming.

    When I was living in Providence,    

An area specifically designed for work or study should be a quiet space, but the example given by PG is regarding his living quarters. I personally don't want to live in a library.

I feel the exact same way. I wear a pair of noise canceling headphones and listen to music so I can block out all of the noise produced by other people. What I found a few days ago, however, was that I had a very, very difficult time concentrating and focusing when I wasn't wearing them or listening to music, where as a year ago that problem was nonexistent. I feel like the only time I can truly concentrate and be at peace anymore is late at night, when everyone else is asleep.

noticed this 110% percent - I started wearing earplugs pumping whitenoise a few years back to help sleep - I need these things all the time now - I have whitenoise running probably 18 hours per day now (except when I'm driving).

I think the opposite is also true. I became able to sleep through nearly anything (nearly including, unfortunately, 4am fire alarms and, more fortunately, 4am wrong-numbers) in the dorms at college, where it was noisy nearly all the time.

I would imagine that exposing yourself to noise (on high volume?) 18 hours a day would cause permanent hearing damage.

18 is possibly the high end, but probably 6-8 per day, plus sleeptime, and it's never 'loud'. I've wondered about hearing loss, but I've done it for a few years now and have not noticed any loss (what did you say?) ;)