Yes, the countryside can be quite full of sound. For example, the cidadas are going outside my windows this evening. But there is a difference between hearing this natural sound and hearing a siren every ten minutes, the swish of tires every minute, the voices of unknown people intermittently, etc.

I think the reason so many turn to constantly on music in the city is it drowns out the more subconciously distressing sounds with sounds that are familiar, that repeat, that you control. Since moving to the country, I only put on music when I want to really listen to it, to the exclusion of all else.