What causes hyperacusis?

There seem to be a few different possible causes for hyperacusis and research into the condition is ongoing; again, I'm going to share some information from the Action on Hearing Loss factsheet with you to highlight what these might be:

It’s possible that hyperacusis is a result of a problem with some functions of the hearing system, which normally ‘balance’ sounds and protect the system. When you’re in a noisy environment, your brain sends information about loud noise back to the inner ear, so that the ‘volume’ can be turned down and the inner ear can be protected. Damage to this ‘feedback mechanism’ may be an underlying cause of hyperacusis.

The brain is also responsible for processing the sound signals it receives from the inner ear. Problems in the way these signals are processed could be another cause of hyperacusis.

Recent research indicates that one cause of hyperacusis may be a reduction in a brain chemical that controls the amount of information arriving in the brain from the sense organs. For this reason, some people who have hyperacusis may also have extreme sensitivity to light (photophobia), as seen in those who have migraines.

We also know that some people develop hyperacusis after sudden exposure to very high levels of noise or after a head injury. Such experiences damage delicate structures within the inner ear, leading to increased sensitivity to noise.

The factsheet also states that hyperacusis can be associated with: