What Happens When Hearing Loss Occurs in One Ear?

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.