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What Happens When Hearing Loss Occurs in One Ear?

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Our auditory systems are highly tuned to these slight discrepancies.

Hearing loss presents itself in a unique manner in each individual. Barring hereditary losses, each occurrence will be slightly varied. Some people will have a sensory loss, while others are conductive. Some will occur at birth, while others do not appear until late in life. One aspect that is sometimes glossed over is whether the hearing loss is bilateral or unilateral. Bilateral means the loss occurs in both ears, whereas unilateral is just one ear. Since the majority of hearing losses are bilateral, this tends to be the default assumption. But unilateral hearing losses can occur and present their own unique challenges and treatment options.

Causes and Symptoms

An estimated 7% of adults in the United States have a unilateral hearing loss. The causes can include anatomical abnormalities, acoustic or physical trauma, chronic ear infections and viral infections. Similar to bilateral losses, they can be sensorineural or conductive, and can have different degrees of severity. That second part is important, as it will influence the language that is used. A unilateral hearing loss, as mentioned, is a loss that occurs in one ear, but wherein some degree of useable hearing remains. The term single-sided deafness refers specifically to a profound hearing loss in one ear and normal hearing in the other. That is, the affected ear is dead.

All hearing losses affect quality of life and communication ability. Unilateral losses unfortunately add even more challenges. Namely, they reduce the capacity to hear in background noise and localize sounds. When we hear normally, our brains are able to filter out the noise we don’t want to hear and focus our attention on a specific talker. This is called the cocktail party effect. It’s not that our ears don’t hear all the other commotion; our brains are just able to ignore it all so that we can carry on a conversation.

Localization refers to the ability to know where sounds are coming from in relation to your position (e.g., behind, to the left). To do this, our brains take advantage of something called the head shadow effect. If a sound is coming from the right, it will arrive slightly sooner and louder to our right ear than our left because our heads create a barrier around which the soundwave must travel. Our auditory systems are highly tuned to these slight discrepancies. They compare and contrast the signals from each ear to determine the origin of the sound. However, this system relies on the signals on each side being even, which is obviously not the case if one ear has a hearing loss. The lopsided signal throws us off, making it significantly harder to know where sounds are coming from. The same is true for hearing in noise. In short, there is auditory chaos.

Managing Unilateral Hearing Loss

Fortunately, there are ways to help manage unilateral hearing losses. One, of course, is to put a hearing aid on the affected ear. This will improve sound awareness on that particular side and balance out the ears, which will benefit hearing in noise and localization. However, this is not always an option. In such cases, we look to specialty devices.

CROS

If the hearing loss is too significant, or speech understanding it too poor, putting a hearing aid on the affected ear won’t help. In this case, a CROS could be used. A CROS looks like a normal hearing aid, but instead of delivering the sound to the bad ear, it transfers it to the good ear. That way, the good ear does all the listening, but the user still gets the benefit of improved sound awareness on the bad side.

Baha

A Baha, or bone-anchored hearing aid, is a surgical implant that vibrates the skull. The sound then travels across the head and stimulates the good ear. A Baha is typically used in cases where a hearing aid is not possible, such as an undeveloped ear or chronic infections. It also can be used in cases of single-sided deafness, but again, this would require the bad ear to be completely dead.

Cochlear Implant

A cochlear implant as also surgically inserted and works by skipping past the ear altogether and stimulating the auditory nerve directly. They were recently approved by the FDA for cases of single-sided deafness. Cochlear implants have the most prerequisites, but are a wonderful option for those who qualify.

Unilateral hearing can be frustrating and disorientating, but there is always hope. Reach out to your local audiologist to start your journey toward better communication. QCBN

By Jeff Lane, Au.D.

Trinity Hearing Center is located at 1330 N. Rim Dr., Suite B in Flagstaff. For more information, visit the website at TrinityHearing.net. Jeff Lane is a doctor of audiology with a passion for improving the lives of others. Dr. Lane may be reached at 928-522-0500 or at audio@trinityhearing.net.

Are You a Cochlear Implant Candidate?

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Cochlear implants are a wonderful invention that can vastly improve the quality of life for those who receive them.

Being diagnosed with a hearing loss can cause conflicting emotions. On one hand, the patient now has an answer that validates all of their experiences and struggles. On the other, they must now undergo the process of managing their hearing loss. The sheer number of hearing aid options alone is enough to overwhelm. But another question may complicate matters: Is a cochlear implant appropriate for me? Realistically, for most patients, the answer will be no. But it is important to understand why, and how it works, in order to make the most informed decision.

Who Needs a Cochlear Implant?

The reason that most people don’t need a cochlear implant is that modern hearing aids are very versatile. Hearing aids currently on the market are powerful enough to easily provide proper amplification for severe hearing losses. They are also sophisticated enough to provide a clear signal in most environments. But they do have their limitations. And that is where cochlear implants come into play.

Simply put, hearing aids can only get so loud. If a person’s hearing is beyond the output limit of the hearing aid, they will not benefit. Particularly for those with profound hearing losses, cochlear implants are the best solution. Because of the way cochlear implants function, which will be discussed more in the next section, they are not subject to the same output limits as hearing aids. Thus, they can provide audibility for any degree of loss.

The other factor is clarity. Some people may have a hearing loss that fits within the output range of a hearing aid, but are completely unable to understand speech. For example, a person may have a moderate to severe hearing loss, but only 30% word recognition. So even though the hearing aid makes it easier for them to hear the sound, speech still sounds garbled and unintelligible. It’d be like listening to a loud, fuzzy radio. Again, this type of patient would benefit greatly from a cochlear implant, as studies show it can help to significantly improve speech understanding. Bottom line, if a patient no longer benefits from appropriately fit hearing aids, they become a cochlear implant candidate.

How Does a Cochlear Implant Work?

When a sound wave approaches the ear, it is funneled down the ear canal to the eardrum. The eardrum vibrates in a specific pattern, which moves the bones in the middle ear (ossicles). The ossicles then vibrate the fluid in the cochlea, which is the organ of hearing. The vibrating fluid stimulates the sensory cells in the cochlea, generating an electrical impulse for the auditory nerve. This is how we hear. However, if the sensory cells or nerve are damaged, this prevents the signal from appropriately reaching the brain, which causes hearing loss.

For those with a cochlear implant, the idea is to essentially bypass the ear altogether, as it is too damaged. Instead, an electrode array is inserted into the cochlea, stimulating the auditory nerve directly. A processor connects to the implant via magnet, collecting and modifying the sound, much like a hearing aid would. There is no acoustic signal, so output limit is not a concern. The signal does not have to travel through the ear, so there is not as much distortion. Cochlear implants are also convenient to use, with some being rechargeable and many being Bluetooth enabled. They can also come with accessories, just like hearing aids. An elegant solution for those most in need.

What are the Qualifications?

In contrast to hearing aids, determining cochlear implant candidacy involves many factors. First, of course, is the hearing exam itself. Candidates must have a certain degree of hearing loss and speech recognition ability of 40% or less. Your audiologist will know the specific numbers. But you must also be a good candidate for surgery. While receiving a cochlear implant is a quick outpatient procedure that is safe at any age, the surgeon must still verify that it is safe to perform the surgery and that there are no anatomical anomalies that would prevent placement. The other big factor is social support. You will need somebody to take care of you during the surgery and while recovering. There are also multiple follow-up appointments with the audiologist, which are necessary for successful outcomes.

Cochlear implants are a wonderful invention that can vastly improve the quality of life for those who receive them. Always feel free to discuss the option with your audiologist if you feel it may be right for you. QCBN

By Jeff Lane, Au. D.

Trinity Hearing Center is located at 1330 N. Rim Dr., Suite B in Flagstaff. For more information, visit the website at TrinityHearing.net. Jeff Lane is a doctor of audiology with a passion for improving the lives of others. Dr. Lane may be reached at 928-522-0500 or at audio@trinityhearing.net.