It seems to be ignoring the very large cultural factor. As an American who has lived around Europe, Asia, and the Middle East, I've observed a great variation in what counts as acceptable table manners. East Asian culture in particular seems to accept a lot more chomping and smacking at the table, and this seems to be a general complaint among Westerners, not just a few individuals.
Secondly, as with anything else psychological, there will be individual variation. I feel there is too much eagerness to isolate some end of a continuum and label it as a syndrome. For example, I've always found notable the fact that some people can't comprehend why neighbors would be bothered by a loud stereo and others can't comprehend how anyone could not be bothered. Though there is a significant psychological variation there, I would not label either group as suffering from a syndrome.
As for dealing with irritating background sounds, in addition to white noise, I've found earplugs very helpful in some situations. The best ones I know of are Hearos Xtreme Protection.
https://www.amazon.com/Hearos-Plugs-Xtreme-Protection-pairs/...