A fridge hums all day in every kitchen, and you only ever hear it in the second after it stops.
Low-grade fear runs at about that pitch. Not the dramatic kind — the background sort that makes you check the phone, reread the message, brace slightly before opening the email.
It is genuinely small. It just never switches off, which is how something small ends up occupying an entire room. The counter isn't to fight the hum. It's to put something louder in the room: work that absorbs you, a person you like, a walk long enough to change your breathing. The hum doesn't stop. It stops being the only sound.