[jijji]

it could also be common sense.. you live in a noisy city and you are wondering what the noise is.... maybe it could be the city itself? how about sleep in a different smaller town and then ask yourself the same question, you'll probably get a different answer.

[kube-system]

I'm not sure if things are really that simple, at least from my personal experience. I think the quality of noise and noise floor can make a difference