I really feel for Arwen. Ever since she was a pup, she's had very sensitive ears, and loud noises of any kind obviously bother her. The bane of her (and by extension, my) existence in winter time is snowmobiles. I don't have any patience for them on any level: they are loud, they stink (the diesel fumes spread and hover in the air long after they're gone) and they seem to attract the same idiot, selfish, prone to drinking-and-driving demographic as the jet skis do in the summer. Their effect on Arwen simply compounds the antipathy. 

When she hears the rip of a snowmobile accelerating, even at a long distance, Arwen panics and skulks over to my feet. She won't even find an interest in her ball. I grabbed this picture of her when we heard the distant approaches of one. You can see by her expression that all is not well.

get it?