For those complaining about noise in apartments: in my experience apartment dwellers are quite considerate and when living in an apartment I never had any major noise problems.
Now that I live in a single home let me tell you about the noise of neighbours mowing their lawns, constant noisy renovations etc. and in general a lot more car noise.
Quite honestly, it was more quiet in the apartments that I lived before.
Edit: and besides, I think people are confusing apartments with the real cause: housing areas with low socio-economic status tend to be more noisy. Correlation is not causation and all that...