Interesting how you mention sound sensitivity at a later age and I would say puberty saw many senses become more acute. Hearing still today (which is not fun living above a crack-house) in my 50's, it is still impressive.
I, also developed my own coping mechanisms and in many situations, people would have no clue that I was on the spectrum. Equally I'm aware of my kryptonite issues, so avoidance is as with many, whilst not ideal, a good plan B coping mechanism.
But with sound, and many coping mechanisms we develop in out brain, I do find falling asleep hard as those mechanisms take focus and the conflict of sleep and awake fall foul in such situations.
But I just love my bluetooth headphones, listening to music and whilst not drown out the outside world (I don't use noise canceling and play music low), it is enough to dull outside sounds that can prove annoying - which are more annoying the more tired I am, as in unable to focus them out.
But you know what my most favorite things in life still is today - a walk in the snow with nobody around. Kinda my happy place and living in outer London, one in which a good memory has its upsides as not that many opportunities to actually do it.
Do you remember having ear infections as a child, and were they painful at all?
Re: Falling asleep - what you've said regarding sleep is another proof point to me that you likely have a hearing imbalance. I found the comment on HN I made going into more detail on theory of how it works - https://news.ycombinator.com/item?id=13657973 - and in it I explain why your brain may not be able to actually stop paying attention to sound, which of course - a natural cycle of falling asleep - will have your senses slowly diminish until you're asleep and not not getting strong signals from them, or rather not reacting to them - making it difficult to fall asleep.
When I was in Grade 2 I had trouble focusing in class - they brought in an audiologist to see if I had trouble hearing. They were surprised that no, in fact, I could hear extremely well - however they didn't recognize that as a problem, hypersensitive hearing.
A standard audiogram only checks to see that you can hear well enough in each ear, at different frequencies, say at 15 decibels. Checking for imbalances they check instead for HOW LOW of a decibel you can hear at different frequencies. Say in your right ear the lowest you can hear 1000 Hz frequency is 15 decibels, but in your left ear you hear at 10 decibels - that would show an imbalance by 5 decibels. Very few audiologists do this test, so I'd be very surprised if you found stumbled into one who did check it in this way.
So soothing.
I am not autistic, but do have high aural senses. As a kid, I could hear well above 20khz. Today, that has rolled off due to age, but my discrimination is still great.
Sounds can sometimes move me to distraction. ASMR, for example. I trigger easily and it is fairly intense.
There is something about the crisp air, dampening on sound that snow presents to us, and what little is heard otherwise seems to just stand right out, like incongruent, but not in a bad way. Just there, present.