I’ve got ADHD and DEFINITELY notice electricity humming through appliances.
Electric fences make noise.
The oven breathes when it’s on
Old tube TVs made a fun little buzz-hum, and the static crackled when I dragged my fingertips a few milimeters from the screen.
When I’m at work I listen to music, because that sound can drown out keyboards from the other room, my computer whirring louder or softer depending on my work, my desk neighbor chewing on seeds, conversations from the meeting room down the hall, the heater kicking on, someone fiddling with the coffee machine, people in the warehouse driving around, plus whatever sounds is coming from outside through the window, dozens of clicks and slides from mice being used, those clicks becoming faster or slower, keyboards clicking, sighs, little grumbles, chairs squeaking, the sound of hair or skin being scratched, the drag of cloth against itself, shoes scuffing on carpet… and so on.
When the brain can’t automagically filter out what is important to notice during background processes, and ignore what is irrelevant before it reaches the forefront of your thoughts as “I noticed this!l EVERYTHING is flagged as important and worthy of being noticed + cataloged.
So with ADHD and autism there’s a lot of brain power being actively used all the time, noticing things, trying to keep those acknowledgements as brief as possible to turn focus back to something productive. Which means adding MORE things like listening to someone talk, or trying to talk back, is way harder to do while also fighting through the simultaneous processing of a thousand sensory inputs that refuse to be ignored.
Music in my ears, familiar, repeating, loud - it drowns out all the ever-changing sounds around me. The sound waves and plastic in my ear physically block me from hearing other things, and since it’s a familiar thing on repeat, i know what comes next, it doesn’t surprise me and drag my attention to it, so I can ignore it and turn that steady ignoring into a background process.
It’s that same logic that makes stimming so attractive and instinctual - hands and mouths and pain take precedence over all other physical input, so wringing hands or chewing on something, or pulling hair forces your brain to focus on THAT, which you control, and forces it to ignore a dozen other low-level but NOTICABLE and IRRITATING stimuli like rough denim or a sock’s seam, or hair itching your neck, or the constant flicker of fluorescent bulbs.
Stimming a way to override how fucking bright and noisy the world is, by tricking your own brain into focusing on something you control.
ADHD is frequently co-morbid with audio processing disorder - we can hear tones and frequencies with our ears just fine, but getting our brain to process a whole language while dealing with all the other distracting shit is hit-or-miss, so you end up hearing English syllables without meaning, and it sounds like the SIMS language.