The Genetics of Auditory Disorders

Several factors can cause auditory disorders. The foundational trigger is genetics. Over 50 percent of newborns that present hearing issues have genetic issues that are the source of the problem. Hearing loss is an inheritance trait known as a genotype.

Genes are the instructions cells follow as they grow and develop. Mutations can develop in genes and passed on from generation to generation, which is known as a familial trait. Mutations can also develop anew. For example, exposure to radiation can cause them.

  • When both parents have a genetic predisposition for hearing loss it is passed onto a child and, if it manifests itself, is known as autosomal recessive hearing loss. This occurs even though both parents have normal hearing — the condition was just dormant in the parents.
  • With autosomal dominant hearing loss, a predisposition from one parent or a new mutation of a gene leads to hearing loss.
  • Males are far more common to be affected by X-linked hearing loss, in which a gene mutation in the X chromosome — of which males have one and females two — manifests itself.
  • Syndromes of the mitochondria, which are vital parts of cells that produce energy, can be passed on genetically and create issues in the functioning of the ear.

The fact is that the inner ear is a very complex example of evolved design. The cochlea, which converts sound waves into electrical signals and sends them through the nervous system to the brain, is a mechanism that requires a vast number of genetic instructions to develop properly.

Only a handful of genetic “wrong turns” can lead to hearing issues. That only about 1 percent of babies are born with genetic hearing loss is actually a profound testament to the majesty of biology.

The Link Between Diabetes and Your Hearing

The inner ear, where sound is converted to electricity (and sent to the brain via the auditory nerve network), is very dependent on healthy circulation. Though very small when compared to other vital organs, it is an energy-intensive part of the body and requires a constant inflow of nutrients.

This is why diabetes, unfortunately, is very much a risk factor for hearing loss. Current research posits that diabetics are two times more likely to have hearing issues than non-diabetics.

Since diabetes inhibits the bloodstream’s ability to transport glucose, a sugar vital to transferring energy to cells, it can prevent the ear from functioning normally. There is also evidence that the elevated levels of blood glucose — diabetes causes glucose to buildup in the blood rather than be transferred to cells throughout the body — damages the blood vessels that are vital to the inner ear.

One fundamental role these blood vessels play is in nourishing the stereocilia, the tiny hair cells that are a crucial part of the inner ear. These hairs cannot regrow or regenerate after being damaged. And a lack of healthy blood flow will damage them.

Diabetes, if untreated, can wreak havoc with much of the body’s functions. It can cause blindness, organ failure, and lead to amputation of extremities.

A 2012 study published in the Journal of Clinical Endocrinology and Metabolism concluded, after evaluating 13 other studies based on over 20,000 subjects, that the higher risk for hearing loss in diabetics was clear and cut across age and other risk factors.

The general advice to diabetics — exercise regularly and keep weight under control — will also lessen the chances of hearing loss. In addition, protecting ears from other risk factors, such as excessive noise, is even more important for a diabetic.

Is an Online Hearing Test Worth It?

Online hearing tests can be a helpful preliminary tool in learning more about any hearing loss you, or someone in your life, is experiencing. They aren’t a replacement for a medical examination by a hearing health professional — but they can be a way to confirm some preliminary concerns about hearing issues.

If there’s a suspicion that there’s a problem, using an online tool can confirm it — or maybe even help you realize that it was a false alarm, a momentary issue related to something like allergies or illness.

They can also be used at regular intervals to track your level of hearing. This long-term approach could help identify issues very early in the process (which is always the best time to seek out professional treatment).

In the case of short-term exposure to extreme sound — such as at a concert or in the workplace — testing online over the course of a few days might confirm that any hearing degradation was a temporary event. Or not.

One thing to keep in mind is the difference between calibrated and non-calibrated tests.

Calibrated tests are more precise — measuring from a baseline across frequencies, resulting in an audiogram — while non-calibrated tests depend on altering the volume level of the device you’re using, resulting in a less detailed result. Both are available online.

But even non-calibrated tests can accurately measure issues with hearing in noisy environments and speech recognition.

Most hearing aid manufacturers offer online hearing tests, including Oticon and Signia.

Six Obscure Hearing Disorders

There are a lot of ways to have hearing issues. Sure, you can stand in the front of the speakers at too many concerts or just be getting old, but there are some exotic conditions too. If you want to have some good party talking points, try one of these rare syndromes on for size.

  • Ménière’s disease
    A disorder of the inner ear that not only produces vertigo, but also incessant ringing, hearing loss, and pressure “pops” in the ear. The causes are murky, with some combination of fluid buildup, infection, autoimmune issues, head trauma, and genetics at work. Because of this, treatment is usually varied and complicated.
  • Benign Paroxysmal Positional Vertigo (BPPV)
    This condition stems from an accumulation of calcium carbonate crystals in the inner ear. And yes, they’re also known as ear rocks (though the technical term is otoconia). Sometimes the condition just goes away, but a range of drugs, surgery, and even head exercises meant to get the ear rocks to roll out of the inner ear are often prescribed.
  • Labyrinthitis
    As a result of infection affecting nerve transmitters and the inner ear, swelling disrupts communication to the brain (vision can also be interrupted). If treated quickly with antiviral or antibacterial drugs it’s treatable, but long-term damage can occur if it is not treated. Dizziness and nausea are also symptoms.
  • Acoustic neuroma
    A rare condition caused by the development of a benign tumor that interrupts hearing and balance information from being transmitted to the brain. Surgery is the common treatment to prevent further complications.
  • Autoimmune inner ear disease (AIED)
    Not well understood, AIED results in the immune system attacking the inner ear, leading to hearing loss, tinnitus, and balance issues. Steroids and blood filtration (plasmapheresis) are common treatments, along with hearing aids.
  • Otosclerosis
    This hardening of the inner ear’s bones is usually a hereditary condition. There are a variety of treatments to deal with what will inevitably lead to continual degradation of hearing.

Better Hearing & Speech Month: Four Families of Hearing Loss

Every May, the American Speech-Language-Hearing Association sponsors Better Hearing and Speech Month. This year’s focal point is “Communication Across the Lifespan.” So, a good time for a brief rundown of the four broad categories of hearing loss: auditory processing, conductive, sensorineural, and mixed. These are the foundation upon which a hearing health care professional will diagnose an individual’s symptoms.

When the issue is the brain’s ability to process the data being provided to it by the hearing apparatus — all the complicated things inside one’s ears — it is an auditory processing disorder. It isn’t a hearing loss problem, it’s a sound comprehension issue, one that is more common in children but will occasionally beset adults. Basically, people with auditory processing disorder just “hear” some sounds differently than the vast majority of people. It can often be mistaken for a learning disorder, so professional analysis is critical.

A more mundane problem is conductive hearing loss. This is a purely physical issue when something is interfering with the pathway between the outer, middle, and inner ear. That can be something as simple as earwax, an infection causing inflammation, or too much fluid in the ear—or something a little more extreme like a punctured eardrum or unusual bone growth.

Sensorineural hearing loss is unfortunately usually permanent. It is a situation where the information flow between the ear and the brain is irreparably compromised. This occurs when the Cochlea and/or auditory nerve are somehow damaged or genetically flawed. The vast majority of users of hearing aids suffer from sensorineural issues.

When more than one of the above is happening simultaneously — almost always conductive and sensorineural in tandem — it’s referred to as mixed hearing loss. Obviously, sorting out which issue is causing multiple symptoms can be a little more complicated.

Hear Better and Stay Out of the Hospital

Treating hearing loss will not only heighten your quality of life on a day-to-day basis. According to recent research, if you’re unfortunate enough to have a hospital stay, it will also make it less likely that you’ll make a return trip.

According to a Journal of the American Geriatrics Society article published in late 2018 entitled “Hospital Readmission Risk for Patients with Self‐Reported Hearing Loss and Communication Trouble,” people over the age of 65 with untreated hearing loss have a 32 percent higher rate of hospital readmission. This was the case regardless of why they were admitted in the first place.

The belief is that a degraded ability to communicate — and hospitals, especially emergency rooms, can be a noisy environment — leads to patients not hearing instructions about continued care or questions about how they’re currently feeling.

“Hospitals are noisy chaotic places, and people with hearing loss may have trouble understanding key information, such as what medicines they should take after discharge, or how they should watch for or manage exacerbation of their symptoms,” said Jan Blustein, one of the researchers at the Robert F. Wagner School of Public Service who worked on the study. “This puts them at risk for difficulties after they are discharged from hospital.”

This is not just a health issue either. Medicare regulations prohibit, in the case of some medical conditions, payment for readmission that occurs less than 30 days after discharge. This is obviously an issue for both the hospital and the patient.

What’s clear is that treating hearing loss is always in a person’s best interest. This study simply adds another reason why.

The Second Generation Opn

For 2019, Oticon has introduced major new capabilities to its Opn hearing aid brand. First brought to market in 2016, this is the first major upgrade of the Opn and brings features like better performance in noisy environments and an improved anti-feedback system.

The new Opn S is built around more powerful processing capabilities and the wealth of data that has been collected since the Opn line was first released. At that time, Oticon stated that their aim was to create a product that would achieve parity — including in noisy environments — between the hearing impaired and people with “normal” hearing.

That goal is getting closer. Oticon claims that the Opn S provides a 15 percent increase in speech understanding, 10 percent increase in memory recall, and 10 percent drop in listening effort compared to users’ experience with the first generation of Opn hearing aids. These figures are from Oticon’s Centre for Applied Audiology Research (CAAR) in Denmark.

Other second-generation features include a significantly improved feedback-control capability via the OpenSound Optimizer. Oticon claims it will be the first hearing aid that will inhibit feedback without directly lowering the hearing aid’s overall amplification level.

Another new feature is the OpenSound Booster, which will enable an iPhone or Android smartphone to be wirelessly linked to the Opn S and act as a booster when the user feels the need. This will be very helpful in noisy environments.

And one of the four new models — the Opn S Rechargeable — will have a long-lasting lithium-ion rechargeable battery.

Your Hearing Isn’t an Island

There’s a tendency in this era of specialization to see the functions of the body as operating in isolation. Maybe even more so hearing loss, since it is treated with very specialized and high-tech devices like hearing aids.

But recent studies make it pretty clear that overall physical health is good for your hearing — and may even put off the need for a hearing aid at all.

Studies have shown that hearing health, especially in people over age 50, is markedly better when that person’s cardiovascular health is better. In fact, data shows that people over 50 who are in good shape are likely to still have a level of hearing commonly found in people in their 30s.

The reason is that a healthy cardiovascular system will include greater blood flow to a person’s head. And healthy blood flow is crucial to the functioning of the inner ear, especially the fine hairs that are part of the cochlea, the contact point where sound waves are translated into what humans hear.

And although the term “cardiovascular health” may bring up images of gym workouts, what is required isn’t too daunting. The benchmark is large muscle movement, the kind that takes place in activities such as walking, cycling, and swimming. The time commitment to that kind of exercise is for 20 to 30 minutes, 5 days a week.

Even with busy modern lives, that’s not too much of a commitment. Especially since the benefits of maintaining a healthy circulatory system are so far-reaching, including deep into the inner ear.

The Evolution of the Hearing Aid

Today’s hearing aids are marvels of modern design. And proof positive of an aspect of Moore’s law, which states that computer-based machines will become smaller and faster as transistors continue to become more efficient. But the hearing aid goes back a long ways.

Hearing “trumpets” date back to at least the 16th century — wide at one end and narrow at the other — and were made from a variety of materials. Eventually advances in physiology led to the discovery of “bone conduction”— wherein vibrations of the bones in the skull actually transmit sound into the ear canal — and devices that were placed behind the ear to focus sound waves were developed in the 18th century.

But none of them were small and subtle.

The 19th century saw a wide variety of disguised hearing aids that weren’t exactly small, but not as obvious. British monarchs even had cunning amplifiers installed in their thrones so they could hear their subjects better without announcing to the world their loss of hearing.

But the harnessing of electricity and the development of the telephone are the direct foundation of today’s artificially amplified hearing aids. The first were boxes worn around the neck, complete with batteries. These gave the user a few hours of better hearing … and probably a sore back.

But like computers, batteries became smaller and smaller over the course of the 20th century. The invention of the transistor in the 1950s ushered in smaller and smaller amplification hardware. Although the transistor radio is what we commonly think of, transistors were actually used in hearing aids a few years before the first transistor radio hit the market.

With transistor technology, hearing aids became small enough to fit in units that could be supported by the user’s ears. The next step was the onset of digital technology, which hit the market in earnest starting in the 1990s. This not only continued the trend of units becoming smaller, but also far more powerful and feature-laden.

For the Sake of the Brain, Treat Hearing Loss

There are troubling new studies that, if nothing else, emphasize the need to take hearing health seriously. The necessity of making regular hearing checkups and related treatment a priority is clearer and clearer.

What studies are showing is a strong correlation between hearing loss — especially untreated hearing loss — and the decline of cognitive functioning.

A study published in June of 2018 in the Journal of the American Geriatrics Society entitled “Longitudinal Relationship Between Hearing Aid Use and Cognitive Function In Older Americans” found that:

“… hearing aids may enable individuals improved auditory input which may delay cognitive decline ‘by preventing the adverse effects of auditory deprivation or facilitating lower levels of depression symptoms, greater social engagement and higher self-efficacy, which protect cognitive function.’”

In other words, being able to hear is crucial to communicating with people and feeling engaged in a community — which has direct benefits to the health of the brain.

This kind of link between hearing and brain function has been noted repeatedly in recent research.

For example, a 2014 joint study by the National Institute on Aging and Johns Hopkins Medicine found similar links between better overall health, including cognitive health, and sustaining hearing.

Published in 2014 as “Association of Hearing Impairment with Brain Volume Changes In Older Adults” in Neuroimage, the study analyzed MRI brain images and found that individuals with untreated hearing loss saw a greater shrinkage in their brain size — which is a natural occurrence in aging — than others.

According to its authors, the findings of the study:

“… demonstrate that peripheral hearing impairment is independently associated with accelerated brain atrophy in whole brain and regional volumes concentrated in the right temporal lobe.”

The authors highly recommend early treatment of hearing loss in order to curtail these effects.

What’s becoming clear is that better hearing is a “better quality of life” issue on more level than one.