What Is Unilateral Hearing Loss?
Hearing loss that affects only one ear is known as unilateral hearing loss (UHL). This hearing loss can range in degree from mild to profound. Even when hearing loss is only in one ear, it can have a significant impact on a person’s day-to-day life. People with unilateral hearing loss have difficulty localizing sounds and understanding speech in noise (Weaver, 2015).
According to Snapp and Ausili (2020), “asymmetry in hearing has been reported to result in a reduced quality of life comparable to, or exceeding, binaural hearing loss.” In addition to this, they found that profound unilateral hearing loss can “have a substantial impact on socialization, learning and work productivity.”
Is Unilateral Hearing Loss the Same as Single-Sided Deafness?
Single-sided deafness (SSD) is one form of unilateral hearing loss. SSD is when one ear is completely ineffective or has no usable hearing. This means that the person might not perceive any benefit from a traditional hearing aid. A person with SSD might have normal hearing or they might have some degree of hearing loss in their better ear.
Who Is Affected by Unilateral Hearing Loss?
Unilateral hearing loss can be present at birth (congenital) or it can be acquired later in life. Unilateral hearing loss can be progressive, meaning it develops gradually over time, or it can occur suddenly. Congenital UHL can occur spontaneously, without having any known risk factors at birth, or it can be caused by craniofacial differences, family history, or an associated syndrome.
Unilateral hearing loss that is acquired later in life can be caused by benign growths in the brain (acoustic neuroma), certain illnesses like viral infections or autoimmune diseases, physical injury to the ear or head, acoustic injury due to loud noise exposure, or idiopathically, which means without a known cause. It is estimated that about 60,000 people per year acquire unilateral hearing loss (Weaver, 2015).
What Are the Symptoms of Unilateral Hearing Loss?
People with unilateral hearing loss have reduced awareness of sound on the affected side. They may also notice unilateral tinnitus, or the perception of sound such as ringing or buzzing, when there is not an external source. Research has shown that our brains rely on hearing from both ears to help us hear best in background noise and to localize where a sound is coming from (Snapp and Ausili, 2020; Shaw and Vaillancourt, 1985). Because of this, acquired UHL has been associated with embarrassment, frustration, anxiety, insecurity, and social isolation.
Some signs of unilateral hearing loss in children include increased listening effort, poor behavior, and poor academic performance. Difficulty localizing sound (identifying where a sound is coming from) is common. Because unilateral hearing loss affects the ability to understand speech in noise, parents might notice that their child seems to hear better when they are in a quiet environment and worse when they are in noisy situations.
How Is Unilateral Hearing Loss Diagnosed?
Suspected unilateral hearing loss should always be diagnosed by an audiologist with a comprehensive hearing evaluation. For adults who experience unilateral hearing loss is sudden in nature, an immediate appointment with an ear, nose, and throat (ENT) or primary-care physician is essential to begin appropriate treatment. For children, a screening at birth, at the pediatrician’s office, or at school can detect a possible unilateral hearing loss, which should be confirmed with thorough testing by an audiologist.
How Is Unilateral Hearing Loss Managed and Treated?
The management and treatment of unilateral hearing loss depends on the degree of loss, as well as the degree of impact on daily life. If the unilateral loss is sudden in nature, the success of medical treatment depends on how quickly treatment is administered after onset of symptoms. Sudden hearing loss should always be immediately evaluated by an otolaryngologist or an ENT.
If the hearing loss is longstanding and if medical treatment is not an option, unilateral hearing loss can be treated with different technologies based the person’s needs and hearing loss. In conjunction with technology, good communication strategies should be used for people with UHL, as they may need an adjusted environment to succeed in speech understanding. Consider reducing background noise on the good side and enhancing speech on the good side.
The following options outline potential technologies for the treatment of unilateral hearing loss:
Hearing Aid
If appropriate, research supports the use of amplification on the affected ear. Hearing aid use has been shown to allow for improved access to conversation, balance of sound, and sound awareness.
CROS Hearing Aid
For those who have hearing loss that cannot be helped with a traditional hearing aid, a CROS system can be considered. A CROS (contralateral routing of sound) system looks like a hearing aid but does not amplify sound for the affected ear. Rather, it uses a microphone to pick up sound presented to the poor ear and sends it over into a device worn on the good ear. Though this cannot help to restore sound localization, this allows improved awareness of sound on the affected side.
Bone-Anchored Devices
A bone-anchored devices can be considered for unilateral hearing loss, though the success of certain goals may depend on the degree and type of hearing loss in the affected ear. Hearing loss that is conductive or mixed in nature, meaning there is some abnormality in the ear canal or middle-ear space, may have good success with a bone-anchored device for balance of sound. However, some research shows that sound localization is still poor with bone-anchored devices.
For single-sided deafness, a bone-anchored devices would route the sound to the better hearing ear, acting similarly to a CROS device. Research shows that bone anchored devices may improve speech perception in quiet and in background noise; however, success can be varied. Bone-anchored devices may require surgery or can be worn on a headband. A trial with a headband and/or a trial using another type of non-surgical device is recommended prior to surgery.
Cochlear Implants
In recent years, a great deal of research has been conducted on the use of cochlear implants for unilateral hearing loss, specifically concerning SSD. Research has shown that cochlear implants can improve speech perception and sound localization for individuals with SSD. Cochlear implants can be considered for children and adults.
The success of cochlear implantation can depend on age, duration of hearing loss, severity of hearing loss, and inner ear anatomy, among other things, so a full evaluation with an audiologist and otolaryngologist who specialize in cochlear implantation is recommended.
Prior to implantation extensive counseling on the pros and cons and realistic expectations for cochlear implants should occur, including trialing non-surgical options. Counseling should also include a discussion of the individual’s and/or family’s communication goals and desired outcomes.
Remote Microphone
A remote microphone, previously known as an FM system, can also be considered a treatment option for UHL. This device can be helpful when the speech of interest is at a distance or in the presence of background noise.
No Treatment
Some individuals may choose not to treat unilateral hearing loss as they feel they are able to access sound and perform well in daily conversations due to their good ear. While amplification may not be the appropriate choice for all individuals, the potential benefits of amplification should be discussed with all patients. Additionally, a trial period of amplification will also be helpful to patients who are deciding whether to treat their loss.
Caution should be exercised regarding the decision not to amplify pediatric patients with unilateral hearing loss. While research shows that many children with unilateral hearing loss are successful as they tend to rely on their good ear, unilateral hearing loss should not be overlooked in pediatric patients. These children may be particularly affected by background noise in the classroom and may experience difficulties socially.
Who Should I Call if I Suspect Unilateral Hearing Loss?
If you suspect unilateral hearing loss, consider consultation with an audiologist and otolaryngologist (ENT). If the unilateral hearing loss is sudden in nature and happens spontaneously throughout the day or upon waking up in the morning from sleep, immediate evaluation by an ENT is strongly recommended, as timing of treatment can affect recovery of hearing. Gradually occurring unilateral hearing loss, especially if associated with dizziness, vertigo, and/or tinnitus should also prompt a visit to an ENT for further evaluation.
For longstanding unilateral hearing loss, consider a consultation with an audiologist for baseline hearing evaluation and discussion of effects on communication and treatment options. If you or someone in your family suspect hearing loss, Find an Audiologist near you to set up an appointment.
References
Park LR, Griffin AM, Sladen DP, Neumann S, Young NM. (2022) American Cochlear Implant Alliance Task Force Guidelines for Clinical Assessment and Management of Cochlear Implantation in Children with Single-Sided Deafness. Ear Hear 43(2):255-267, March/April 2022. | DOI: 10.1097/AUD.0000000000001204.
Dillon MT, et al. (2022) American Cochlear Implant Alliance Task Force Guidelines for Clinical Assessment and Management of Adult Cochlear Implantation for Single-Sided Deafness. Ear Hear. www.audiology.org/wp-content/uploads/2023/01/ACI-Alliance-Guidelines-for-Adult-CI-for-SSD.pdf.
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