Difference in engine sounds?

Today I was lying by the bay reading and a boat drove by, and the sound of the boat made me feel at eaze... almost peaceful. Where as the sound of cars literally stresses me out. Not, I have a deadline, or a presentation im not prepared for, or final exam stress... but it definitely adds a little bit of stress to my life. This is very inconvenient considering I live in a city, even more so because my apartment faces a busy road that with the speed of the cars can only be categorized as a highway. Its funny how two sounds which are so similar can evoke such different feelings. Of course these feelings stem from my favorite place in the whole world, my childhood lake house. Its out in the middle of nowhere so the only sounds that can be heard are nature and the engines of boats and jetskies alike. Because of this I will always be filled with peace and happiness at the sound of a boat engine... to the point where I have decided most definitely I will be living on a lake where I will be listening to the sound of boats and NOT cars!