What Is Hidden Hearing Loss and How Is It Diagnosed?

Are you uncomfortable in a crowded restaurant or during a party because you just can’t keep up with a conversation with those nearby?

An inability to clearly have a conversation in a noisy environment is among the early warning signs of hearing loss. Those who schedule a hearing test discover that they are experiencing no measurable hearing loss. Unfortunately, their discomfort in noisy environments continues and they begin to avoid restaurants and social events.

The condition we have just described is a brain condition known as hidden hearing loss, which is not identified through typical hearing tests. Hidden hearing loss has a significant impact on your quality of life, and due to the isolation it can cause, it can begin to take a toll on your mental and physical health and well-being.

Port Credit Audiology & Hearing Aid Clinic is concerned about the impact of hidden hearing loss on the quality of life of individuals in Port Credit, so we are doing what we can to raise awareness of this hearing health condition as well as identify and treat it.

What Is Hidden Hearing Loss?

In simple terms, hidden hearing loss (HHL) is a form of hearing loss that is not detectable using a standard hearing test, which is not designed to evaluate the underlying nervous system.

Estimates of the prevalence of hidden hearing loss are somewhat limited due to the nature of the condition. According to a study published in 2020, “the prevalence of this type of dysfunction as described by subjects with self-reported hearing difficulties despite having normal hearing thresholds has been estimated at 12%–15%.”

Hidden hearing loss is caused by a neurological defect in the cochlea. Though the exact cause remains elusive, risk factors associated with HHL include noise exposure, aging, ototoxic drugs, and peripheral neuropathies.

Some studies show that HHL is associated with a loss of synapses, or connections,between the sensory hair cells in the cochlea and auditory nerves, causing the signal to arrive incomplete or missing information needed to interpret words. This is known as cochlear synaptopathy.

Some researchers believe that HHL could result from the nerve axon or ‘cable’ that connects nerves to each other. Low-level noise exposure over a long period of time coupled with aging can lead to the deterioration of the nerve axon. There can also be issues with the cells that make myelin, a substance that insulates neuronal axons, which is responsible for the smooth and rapid communication of information between nerves. This could stem from autoimmune disorders like Guillain-Barré syndrome or be linked to food poisoning, the flu, hepatitis, and the Zika virus.

Common Signs of HHL

Unfortunately, there is no established set of guidelines for identifying hidden hearing loss, but symptoms or conditions to watch for include:

How Is Hidden Hearing Loss Diagnosed?

The reason that hidden hearing loss often goes undetected is that the standard “pure-tone” test is unable to identify it. Audiologists use a complete series of tests in the diagnostic process in order to identify conditions like HHL.

Comprehensive hearing assessments may include:

Word-recognition scores, according to NIH funded research, are lower in those with cochlear nerve damage. Consequently, although you might hear certain sounds, the nerve damage would prevent those sounds from being processed correctly by the brain.

Thanks to this research, speech-in-noise (SIN) testing, which involves listening to recorded segments of speech set in an increasingly noisy background , has become one of the most common tools for diagnosing HHL.

Hidden hearing loss can be mistaken for attention deficit hyperactivity disorder (ADHD) as well as central auditory processing disorder, but these conditions originate at different levels of the brain.

Experimental Tools for HHL Diagnosis

The team at Massachusetts Eye and Ear have developed two tests to help identify hidden hearing loss.

The first measures electrical signals from the surface of the ear canal to evaluate their capacity to encode subtle and rapid fluctuations in sound waves. The second measures changes in the diameter of the pupils, which reflect the amount of effort needed to understand something, while listening to speech in noise.

By combining the results of the two tests, researchers were able to predict who would be able to follow a conversation in background noise and who would struggle. This is a promising testing technique on the horizon for testing HHL, but not yet commercially available.

How Hidden Hearing Loss Is Treated

The bad news is there is no direct treatment for hidden hearing loss, though researchers are working on various medications to prompt neurons to grow new synapses.

Until there is a breakthrough in that area of research, individuals with slight or mild hearing loss could benefit from low-gain hearing aids with speech-in-noise programming features.

There are also additional assistive listening devices, like a personal FM system or a mobile app that can caption live conversations, to help. Those experiencing HHL can take advantage of assistive listening systems in theatres, places of worship, airports, and other public places.

Lifestyle changes may include seeking quieter places to enjoy conversation. This might include going to restaurants earlier during slower times, arriving at events early to reserve a seat closer to the speakers, and inviting smaller groups of people to join you in conversation at social events.

It is important that you do not ignore your problem and withdraw, because avoidant behavior and social anxiety can have a significant impact on your mental health.