I haven't noticed it getting worse. It's hard to know because it seems to vary a lot depending on the nature of the sensory stimuli, the situation, and my overall mood at the time. Also whether or not I'm trying to focus on something comes into it. If I were to test myself by immersing myself in an overstimulating environment, I'd probably feel less upset than I would if I had to focus on something at the same time, but if I succeeded in becoming hyperfocussed, that in itself can stop me from noticing the other sensory input. It's never caused me to have a meltdown (unless you include my early childhood when I used to cry and kick off if my mother took me shopping in the busy market, and I can't remember how bad that was, probably no more than an ordinary tantrum), but I've been known to feel horribly fratchety and kind of sore inside. I tend to look after myself pretty well in that respect, if it starts getting too much I get out of it.