Hyperacusis can come on suddenly or gradually. It can initially affect only one ear but generally speaking, within a short time, the condition is almost always bilateral. It can be mild or severe. Often, people who have hyperacusis also have tinnitus, or phantom noises in their auditory system (ringing, buzzing, chirping, humming, or beating).  Research has shown that about half of all people who have tinnitus, also have reduced tolerance for moderate or loud sounds, known as hyperacusis. No one is quite sure how many people in the world suffer from hyperacusis without tinnitus.

Adults and children can develop hyperacusis: certain birth conditions are associated with hyperacusis, including Williams Syndrome and autism.  Since the auditory system connects the outer organs of hearing with the central nervous system, through a complex series of neural pathways, that literally pass through or coordinate with many diverse areas of the brain, there are endless possibilities for dysfunction that may contribute to hyperacusis.

Anxiety, stress, and/or phonophobia may be present in both types of hyperacusis. Someone with either form of hyperacusis may develop avoidant behavior in order to try to avoid a stressful sound situation or to avoid embarrassing themselves in a social situation that might involve noise.

A person suffering from hyperacusis might be startled by very low sound levels. Everyday sounds like shutting doors, ringing phones, television, running water, ticking clocks, chewing gum, cooking, normal conversation, eating, dishes, and other sounds will hurt his/her ears.