Hearing loss in one ear


Contributed by Joy Victory, Editor-in-Chief, Healthy Hearing
Last update 2022-01-17T00:00:00-06:00

Most people who are hard of hearing suffer from what is called ‘binaural’ hearing loss, which means that both ears are affected. But some people can lose hearing in only one ear. It can develop at birth or later in life.

This is known as unilateral hearing loss Where unilateral deafness, depending on the severity of the hearing loss. We usually speak of “single-sided deafness” (SSD) when the degree of hearing loss is profound or nearly profound. Learn more about degrees of hearing loss.

Hearing loss can occur gradually or suddenly. When it occurs suddenly, it requires prompt treatment and should be treated as a medical emergency. This is called sudden sensorineural hearing loss (see below).

How hearing loss in one ear affects hearing

We were designed to have two ears for a reason: the brain uses both ears to locate the location of a sound and to improve the quality and range of hearing.

Losing hearing in one ear presents unique challenges. Depending on the severity of your hearing loss:

  • You can’t always tell where a sound is coming from: Your brain knows where a sound is coming from and which ear receives the sound first, which is called sound localization or directional hearing. When a person can only hear well in one ear, they may have difficulty determining where the sound is coming from.
  • You may have difficulty hearing in noisy environments: Your brain is responsible for selective listening, that is, filtering out unnecessary noise. It’s harder to do without the help of a second ear. In a noisy environment, a person with an SSD may find it difficult to concentrate on a single person’s voice.
  • You might find it harder to tell how loud a sound is: The brain “hears” a louder sound when it is perceived by both ears than if the same sound at the same decibel were perceived by only one ear. This is because the brain receives signals from the nerves located in both ears and uses this information to process sounds.
  • You may find it difficult to perform several tasks: Due to all of the above, single-sided deafness increases the cognitive load on the brain, leading to auditory fatigue. The more noise, the longer it takes for your brain to focus on the tasks at hand. If you’re also trying to listen to someone talking, you might miss a lot of what’s being said.

The “head shadow” effect of unilateral deafness

If you have single-sided hearing loss, you will likely experience what is known as the “head shadow” effect. Due to the way sound waves travel, high frequency sounds do not “bend” to the side of the working ear, which means a person never hears them.

“The head essentially acts as a shield, preventing sounds from the worse-hearing ear from reaching the better ear,” Cleveland Clinic audiologist Sarah Sydlowski explained in an online chat with patients.

The end result is that speech can sound muffled because a person cannot hear high frequency sounds like “s” or “f”.

Causes of hearing loss in one ear

There are a number of potential causes of hearing loss in only one ear, including but not limited to:

Sometimes a cause cannot be identified or is due to a combination of factors.

Sudden hearing loss in one ear

Hearing loss in one ear can develop quickly. You should always act quickly if you or a loved one experience sudden hearing loss, no matter how severe. As it develops, you may also notice that you have “double hearing”, known as diplacusia.

You should always see a doctor as soon as possible if you suffer from sudden hearing loss.

The sooner you seek treatment, the better your chances of full recovery. When hearing cannot be corrected by medical treatment, it often results in single-sided deafness, which occurs about 15% of the time.

Treatment options for single-sided deafness

For people with mild to moderate hearing loss, a hearing aid may be enough to amplify the sounds you can’t hear.

Severe to profound unilateral hearing loss is often permanent, but can sometimes be treated with devices worn on your working ear. Your hearing care professional will perform a hearing test and ask you questions to try to identify the cause of your hearing loss. From there, he or she might recommend a CROS, BiCROS, or bone-anchored hearing system:

Contralateral Sound Routing System (CROS)

CROS hearing aids shown

A CROS hearing aid system is designed for people with near total hearing loss in one ear, but normal hearing in the other. A CROS detects sounds occurring on the deaf ear and routes them to the good ear. This requires wearing a device on each ear: On the non-functional ear, the person wears a transmitting device, and on the functional ear, the person wears a receiver that processes sound and outputs it via a microphone. This sound is not amplified beyond normal because the person has relatively normal hearing.

BiCROS hearing aids work the same way, except they are designed for people with a functional ear with moderate to severe hearing loss. This means that the working ear not only receives the sound from the transmitter on the other ear, it also receives the amplified sound through a typical hearing aid. Several different manufacturers make CROS and BiCROS hearing aids.

Following: What are CROS and BiCROS hearing aids?

It’s important for patients to realize that these devices redirect sound, but don’t “restore” hearing to deaf ears, according to Erika Woodson, MD, medical director of the Cleveland Clinic’s hearing implant program, in a online chat with patients on devices. “You won’t hear in stereo. The benefits of these hearing strategies are improved 360-degree sound perception, but you won’t be able to localize the sound.”

Bone anchored hearing systems

A man with a bone-anchored hearing aid.
This man wears a Ponto 4
bone-anchored hearing aid.

Image courtesy of Oticon Medical

Some people don’t find CROS hearing aids helpful. An alternative is a bone-anchored hearing system, which requires surgical implantation. These devices, also known as bone-anchored hearing implants, send sound vibrations directly to the inner ear through the bone of the skull, a process known as bone conduction. This can be helpful because middle ear and ear canal problems can prevent sound waves and signals from reaching the inner ear. In these cases, standard hearing aids are ineffective.

Cochlear implants work by directly stimulating the auditory nerve. They are not normally used for single-sided deafness, although the FDA in July 2019 approved a cochlear implant device from Med-El specifically for single-sided deafness.

For more information

If you are interested in hearing solutions for single-sided deafness, consult a local otolaryngologist. Oticon Medical, which manufactures the Ponto 4 bone-anchored hearing system, also has a searchable supplier directory.


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