I do think that the “intense world theory”– at least, the idea that autistic people feel things very intensely, if not the rest of it– does accurately describe some aspects of autism. The term “sensory processing disorder” refers to that idea specifically.
For me, it explains a lot of my trouble with noise and distractions.
It’s very difficult for me to separate sounds I want to listen to from background noise. What some people call the “cocktail party effect”— the brain’s ability to automatically filter out and focus on the most important or relevant sounds– is basically nonexistent for me.
I know that I don’t have hearing loss– I’ve had the basic kind of hearing tests, that measure whether you can hear very faint sounds at various pitches. I do fine on those. But put me in a noisy restaurant and I might as well be hard of hearing. Levels of noise that other people seem to consider acceptable affect me much more. I mishear words (or just find them completely garbled) in every sentence. When I’m very tired/stressed/etc., it seems like I have the opposite of the “cocktail party effect”– the more I try to listen to one person’s voice, the louder everything else gets, drowning them out.
Here is another autistic person’s description of similar problems and the stress they can cause.
This collection of problems can be described by a relatively new term, Central Auditory Processing Disorder. There’s some debate about whether CAPD should be considered a standalone condition, or whether it only happens as a symptom of autism or some other wider condition, but the existence of people with problems like mine is pretty clear.
My problems with hearing are the biggest way that sensory processing issues affect my life, but they can manifest in a lot of different ways. The DSM criteria mention hyper- and hypo-sensitivity, meaning that autism includes finding sensations both unusually overwhelming and unusually mild. Some autistic people are very sensitive to light, or noise, or scent, and find that, for example, light levels that other people consider normal will hurt their eyes. Another autistic person who is hyposensitive to light would find even very bright lights neutral or pleasant, and might have to be warned not to stare at the sun.
Many autistic people also have a few specific sensations (sounds, smells, textures, anything) that they strongly dislike, out of proportion with a normal preference. You know the “fingernails on a chalkboard” sound, that makes so many people cringe? Many autistic people have that kind of reaction to other things, from the buzzing sound of an electric fan to the texture of boiled vegetables to the way the tag on your T-shirt pokes the back of your neck. This post by Cynthia Kim has more information about sensory processing issues in general.
(Edited to add: There is a specific word for having this kind of strong negative reaction to a sound: misophonia.)
Personally, I’m pretty lucky in this realm. I don’t have very many of these sensitivities, and those I do have aren’t too strong or are easy to avoid. This post was me thinking about my sensory likes and dislikes.