September 18, 2017

The Impact of Unilateral Hearing Loss

Have you ever noticed how some things are just meant to work together? Take for example Abbott and Costello, without whom we’d still not know who was on first. Or how Fridays are better with fish and chips. Not to mention all the other pairings like salt and pepper, day and night, cookies and cream, or if you take a holistic approach to health, yin and yang. Our bodies were even designed to work in pairs with right and left legs, arms, eyes and ears.

Like many people, I tend to take these natural pairings for granted. However when my son broke his leg and this sudden loss of symmetry completely disrupted our lives, it reminded me of how important symmetry is. Fortunately, kids are resilient so with the support of a walker along with a little motivation and confidence he was just as mobile as ever. Shortly after that on our family vacation my husband’s ear plugged up with wax and he spent the entire vacation struggling to hear with just one ear. Luckily for all of us he is married to a very good audiologist who was able to remedy this as soon as we returned home. But, for many people with unilateral hearing loss it is not so easily fixed, and living with this condition can be challenging if not frustrating.  

Having hearing loss in only one ear seems like it would not be a big deal because after all you still have one good ear. And this is true when you’re in a quiet environment listening to only one person. But, as we all know our world is not silent. Once someone with unilateral hearing loss leaves their quiet haven, they struggle to follow conversations. But why is that?

It comes back to how our bodies were created. We were designed with two ears but only one auditory center. Even though our ears can work independently they work best as a team. Each ear collects sound in the environment and then sends that sound to one sole auditory center in the brain, where it is analyzed and interpreted. When the auditory center receives information from one ear only, it is essentially missing 50% of the data needed to do its job. Imagine if you had to do your job with only half the equipment or information you needed. That job becomes much more challenging if not impossible.

When the auditory center does not receive equal input from both ears a few things happen. First, it struggles to localize where a sound is coming from. To localize, the auditory center compares the arrival times of sound from each ear. The ear closer to a sound transmits the signal a few milliseconds faster than the ear further away. When you have a unilateral hearing loss the good ear will always send the signal first, even if the source of the sound is nearer the bad ear. Which essentially means this person will always assume sound is coming from the good ear side. This is due to something we call the “head shadow effect”. Essentially your head acts as a natural barrier, both dampening and delaying sound as it crosses over the head. This works great for things like localization but is not so great when you have a unilateral hearing loss.

Because of the head shadow affect, some softer speech sounds spoken on the bad ear side may not make it past your head to the good ear. These soft sounds are mainly higher frequency voiceless consonants such as s, sh, f, t, p, and so on. If you are not able to hear these sounds clearly you are not able to follow along with a conversation.

Head shadow affect aside, the soft high-frequency voiceless consonants will always pose a problem for those with unilateral hearing loss when there is background noise present. When we use two ears to hear there is a natural boost in the volume of the sound we hear. The technical term is “sound summation” but basically it means that when both ears hear a sound the volume of that sound is more than doubled, making it easier to hear.

But now for the good news. With the many advancements in technology we rarely have to struggle for long. If you have a bad leg there are options. Depending on the condition of the leg, patients have access to walkers, crutches, braces, prosthetics, or even wheelchairs. The same is true if you have a unilateral hearing loss. Depending on the cause and amount of hearing loss you could benefit from a hearing instrument, bi-cros system, bone anchored hearing instrument or a cochlear implant. But, then again it may be even easier than that. You may just need a good ear cleaning.

The International Journal of Medicine published the article “Impacted Cerumen: Composition, Production, Epidemiology and Management” by J.F. Guest et al.  The article discussed a study on the prevalence of hearing loss related to cerumen (ear wax) build up in the ear canal. In the study, a whisper test was administered to 14,877 elderly patients. Twenty-six percent of the patients failed the test initially, but after having their ears cleaned 9% of those patients that originally failed the screening passed.

Okay, so I know 9% does not sound that exciting and a whisper test is not in any way a diagnostic hearing evaluation, but I wanted to mention this study to get my point across. That 9% was equivalent to 343 patients. Think about that for a second, three hundred and forty-three patients, like my husband, experienced an immediate improvement in hearing after a simple ear cleaning.

If you experienced a sudden hearing loss, early treatment is even more important. A sudden hearing loss can be caused by a virus. Typically, it will occur a few weeks after you were sick but it can also occur without a preceding illness. Sudden hearing losses like this can be treated with steroids which may bring back some or all of the hearing. However, steroids have the best chance of working if started within the first 2 weeks of the loss occurring. Waiting longer than two weeks significantly reduced the likelihood of the steroids working.

Of course, not all unilateral hearing losses will be that easily remedied. Some are associated with more serious conditions like middle ear infections, otosclerosis, cholesteatomas, or acoustic neuromas. For these it is important to see an Ear Nose and Throat doctor to discuss treatment options.

I’m not able to discuss all the possible causes of a unilateral hearing loss here as this blog would go on and on. Also, my main goal was not to write a thesis but rather to explain the effects of a unilateral hearing loss and to stress the importance of early treatment. Why early treatment? Because addressing the issue can avoid a larger problem later.