Try ear plugs that he can carry around and put in when things get noisy. You could also try desensitizing therapy. I sometimes put my fingers in my ears, but I should get ear plugs myself, only my sensitivity isn't has bad as others on the spectrum. Years ago, after my mother stopped driving, I had to take her to a number of big family get togethers at rented halls. Because the music was always blaring, I ended up spending much of each occasion out in the lobby or in the rest rooms. I can NOT understand at all how anyone could stand noise that LOUD! I also don't like bright, glaring lights, and have skin sensitivity issues, too.
My mother passed away about 8 years ago, so I no longer have to take her to these torture fests. Naturally, I won't subject myself to that without it being absolutely necessary. I didn't have much choice back then. I was living with my mother and not working steady, so she was partly supporting me. It was fair that I help her out with things like taking her to these parties. I am glad not to have to go any more, though.
I wish I could come up with some other, better ideas, but I don't have any others.
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If a man does not keep pace with his companions, perhaps it is because he hears a different drummer.
Let him step to the music which he hears, however measured, or far away.--Henry David Thoreau