A baby cries or a truck screeches its brakes to a halt and the sound is excruciating. The person who has hyperacusis can't simply get up and walk away from noise. Instead, the volume on the whole world seems stuck on high. Hyperacusis is a collapsed tolerance to normal environmental sounds. Ears lose most of their dynamic range.
Dynamic range is the ability of the ear to deal with quick shifts in sound loudness.
Suddenly everyday noises sound unbearably or painfully loud. The disorder is often chronic and usually accompanied by tinnitus, but can occur in patients who have little or no measurable hearing loss. Hyperacusis differs from recruitment, which is an abnormal growth in the perception of loudness accompanied with hearing loss. With recruitment, loud noises are uncomfortable. With hyperacusis, all sounds are too loud.