Hyperacusis is reduced tolerance to ordinary sound. People with it find everyday noises — cutlery on plates, a kettle, traffic, a phone ringing — physically painful or distressing at levels healthy ears find unremarkable. It is not the same as not liking loud sounds. The threshold is genuinely lower.
Mechanistically it is thought to involve increased central gain in the auditory pathway — the same theme that runs through tinnitus, which is why the two often coexist. Hyperacusis can also follow specific triggers: a sudden loud noise, head injury, Lyme disease, Bell's palsy, or migraine.
It is different from misophonia (a strong specific aversion to particular sounds, usually human ones, that is not really about loudness) and from phonophobia (anticipatory anxiety about sound). Distinguishing them matters because the treatments differ.
The treatment for hyperacusis is gentle, graded sound exposure, often through sound generators or hearing aids, combined with CBT. The big trap is over-protection: wearing earplugs in ordinary rooms because everything feels too loud usually deepens hyperacusis over weeks. Save earplugs for genuinely loud environments.