The awful, increasing roar of a motorcycle driving by on the street beside you, absolutely ! I detest that, it scares me every time it happens, and makes it a tad difficult to be out on town acting normal, considering I jump like 2 metres off the ground each time I hear it they really should try and dampen the noise of those things in some (any!) way, since it makes me want to wipe motorcycles from the face of the earth :c
And no question about it, popping balloons are the perfect nightmare for my shaky aspie-soul. Or rather, it is the knowledge that a balloon is going to pop soon. When people play around with them on parties etc,. I simply wish to scream at them to leave the balloon be. Never dare mention it, though, and when the inevitable pop reaches me (if I haven't already left the room panicking) I feel as if I'd just received an electric shock
Also, as many have already said, the sound of a baby/young child crying is among the definitely ear-killing phenomena of our world Then, personally I can hardly stand the pronounciation of varying forms of American English (I'm a very nerdy anglophile, and strongly prefer R.P or any kind of British/Irish accent (guess what my special interest is *lol*)) But no offence, Americans out there, it's just me being grumpy and narrow
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~What is life, so full of care, if we have no time to stop and stare.
-William Henry Davies