Hidden hearing loss (HHL) also known as cochlear synaptopathy), is a type of hearing impairment caused by exposure to loud noise. Loud noise not only damages hair cells in the inner ear, but can also damage the ear’s nerve cells. When this happens, information cannot be sent to the brain accurately because the nerve cells have lost their connections (synapses) to the hair cells in the cochlea. A reduction in the amount and quality of information from the ear to the brain results in increased difficulty correctly interpreting and understanding.
A hidden hearing loss doesn’t normally affect a person’s ability to hear quiet sounds, but it makes it harder to hear sounds when there is competing background noise. This type of hearing loss is usually not detected by conventional hearing tests.