Tess
That's not a category, that's a sensory memory. I'm talking about "Unintentional Domestic Hums." The only member is the specific frequency of a refrigerator motor when the seal is failing. It makes your teeth twitch. It's distinct from a fan or AC because it's a structural interference. People group it together but they're wrong. If you try to put a buzzing fluorescent light in there, you're just breaking the whole logic.