Hank Green of SciShow offers his explanation as to why certain sounds are considered to be so awful to listen to. It’s not the actual sound, but the frequency.
…it turns out that there’s a good scientific reason why certain sounds set most people’s teeth on edge: human ears are extra sensitive to a particular range of pitches. Although where that sensitivity comes from is still up for debate. In 1986, a group of neuroscientists tried to get to the bottom of these intense reactions by doing what so many researchers do: unpleasant things to volunteers. Specifically, they asked 24 adults to rank a series of 16 sounds based on how unpleasant they thought those sounds were. And although that isn’t a very big sample size, the noises that were consistently rated the nastiest — like the sound of a fork scraping a plate or squealing brakes — all had something in common: They share a frequency range between 2,000 and 5,000 hertz, where our ears happen to be especially sensitive.