Another problem is that with a cheaper flat came generally noisier neighbors, i.e. frequently throwing out late-night parties, denying anyone around the luxury of sleep.
Then there are dogs whose owners don't seem to realize that dogs need to be walked and otherwise they will bark without end. This happens most often in the mornings and can go on for 2 hours easily and sets the tone for the day just right... It seems dog owners develop a special indifference to noise and their dogs.
All of that made me miserable. There were actually moments when this situation triggered suicidal thoughts.
I don't have a problem with cars passing by on the nearby high-speed road. If anything, the sound they make (very different from the sound of cars in traffic) is calming during the night.
I've recently got a new job which pays a lot better than the previous one, so in a couple of months I plan to move to a quieter neighborhood.