All I know is that Dyson hand dryers and Animal vacuum cleaners are well above my pain threshold. I think using them regularly certainly would damage my hearing. I actively avoid them.

It's down to diversity, I suppose. I'm no super-hearer (I don't really think my hearing is different to anyone else's) but obviously the engineers at Dyson didn't care about people like me.

I use another brand of 'blade' type dryers (I forget which) every day and it's fine.