Let’s say you’ve had difficulty understanding people in a noisy place, like a restaurant or party. You’ve asked people many times to repeat themselves. So, you’ve gone to get your hearing tested, only to find that you’ve passed the test with flying colors. And yet, when you find yourself in busy spaces with a lot of background noise, you struggle to hear conversations and speakers’ voices. What’s up with that? Chances are, it could be a hidden hearing loss .
Hidden hearing loss describes a type of hearing loss that is not easily detected on regular hearing tests – and that’s not a fault of the sophisticated hearing tests that have been designed to identify hearing loss.
Hearing tests are usually taken in very quiet environments, such as a sound proof booth or room with a hearing specialist. Hearing tests are excellent at detecting hearing loss within this quiet milieu. The problem is, hidden hearing loss is only a problem when you are trying to pick up specific sounds and speakers’ voices against a very noisy background.
About six years ago, hearing specialists, researchers, and scientists identified hidden hearing loss. Recently, scientists at the University of Michigan, in collaboration with scientists at Nanjing University in China, have identified an unexpected new cause for hidden hearing loss, which is instrumental in finding ways of identifying and treating hidden hearing loss itself.
According to Dr. Gabriel Corfas of the Kresge Hearing Research Institute at U of M’s Department of Otolaryngology – Head and Neck Surgery, “If people can have hidden hearing loss for different reasons, having the ability to make the right diagnosis of the pathogenesis [cause of the condition] will be critical.”
In the course of this study, Dr. Corfas and Guoqiang Wan of Nanjing University, discovered that a deficit and disruption in the production of a substance called myelin could be linked to permanent hearing damage. Among the mice in their study, they found that a loss of myelin in the auditory nerve eventually lead to permanent hearing loss – even after the myelin regenerated.
Researchers of this study identified exposure to loud noise over long periods of time could permanently damage hearing, destroying the connection between synapses. A previous cause for hidden hearing loss to traced to this loss of synapses. While in quiet environments, only a few synapses are required to pick up sound, when you find yourself in louder environments, it may become more difficult to hear.
Dr. Corfas talks about the link between exposure to loud noise and the development of a (hidden) hearing loss: “Exposure to loud noise is increasing in our society, and children are exposing themselves to high levels of noise very early in life. It’s clear that being exposed to high levels of sound might contribute to increases in hidden hearing loss.”
As it stands, there are no current treatments for hidden hearing loss. However, researchers are working on a drug that would treat it. “Our findings should influence the way hidden hearing loss is diagnosed and drive the future of clinical trials searching for a treatment. The first step is to know whether a person’s hidden hearing loss is due to synapse loss or myelin/heminode damage,” says Dr. Corfas.
If you’ve had a difficult time recognizing speech, you may be experiencing a hearing loss – whether or not it is a hidden one. If you struggle in conversations or to follow speakers’ voices, it may be time for a hearing test.
Come visit us at one of our Puget Sound Hearing Aids and Audiology locations. We provide comprehensive tests and hearing aid fittings.