High-powered hand dryers in public bathrooms. These pieces of shit: http://www.exceldryer.com/products_xlerator.php
My ears are really sensitive to particular types of noise and nothing on earth that I've heard so far is as painful as these. I have to cover my ears or run out of the bathroom or I start to lose it.

On the opposite end, these lead to extreme happiness: http://airblade.dyson.com/