Put it this way, mines no walk in the park as I've already gone from a mild T to where I am now. I have a 12.5khz ish really shrill dentist drill tone, a 6khz drone like tone, and various shades of hissing noises. My brain and ears all contain noises, and sometimes I get zaps, or electrical like sensations that spontaneously erupt around my head. I have no clue what is considered severe, because of the subjective nature of the beast. None of us know what anyone else is hearing. One mans moderate tone may be considered lethal by someone else, and another's mild sound might be considered more moderate by others.
It's ultimately a perception though, so if we are stressed or specifically focussing on it it will seem way louder.