From DMJ Productions

Hyperacusis is an increased sensitivity to sound and a low tolerance for environmental noise. Definitions of hyperacusis can vary significantly, but it is often categorized into four subtypes: loudness, pain, annoyance, and fear. It can be a highly debilitating hearing disorder.

There are a variety of causes and risk factors, with the most common being exposure to loud noise. It is often coincident with tinnitus.

From Wikipedia