There's something to this, but there's also the fact that any given sound gets literally lost in the noise.

That's exactly what it is, for me at least. The slightest noise of something other than nature is enough to throw me completely, the best I can do living in a city is to work in an environment where the background noise has a masking effect. It's either no noise or a constant background drone loud enough to mask any single interrupting sound - anything in between is unworkable for me.

As much as I love the mountains and forests, I've come to realise that I like the idea of solitude a lot more than the reality of it. And so I find myself living in large cities, constantly seeking noise because it's the only way I can find peace.

When the ambient sound level gets too low, I get a strange feeling in my ear -- kinda like a hand or leg "falling asleep". It's really distracting.

White noise, and ambient "study" music is great -- it's like a null placeholder, I can focus and I remember hearing nothing instead of hearing silence.