Unilateral Hearing Loss

Unilateral hearing loss refers to the condition in which a patient has normal hearing in one ear and a hearing impairment in the other ear. When the impaired ear has a profound loss of +90dB (decibels), the condition may also be referred to as single-sided deafness.

Whether moderate or profound, unilateral hearing loss can significantly affect a person’s quality of speech understanding. Though the person can hear and communicate relatively well, they may often miss much of what is being said. If they are in a difficult listening situation (for example, excessive background noise) then they are often using a great deal of mental energy to follow a conversation. Since they lack hearing in one ear, they also lack binaural summation (which is using the acoustics of both ears together to improve understanding of speech). Besides causing fatigue, this can also result in frustration and stress.

unilateral hearing loss
Specialized hearing aid technology allows a person with unilateral hearing loss (single-sided deafness) to hear on their deaf side. The system is referred to by the acronym CROS, which stands for contralateral routing of signals.
Another handicap of unilateral hearing loss is the inability to distinguish the direction and distance a sound is coming from, also known as localization. This may also pose a safety issue for the patient (for example, not hearing a person approaching from behind or an emergency vehicle in traffic).

Causes of Unilateral Hearing Loss

There are numerous possible causes of unilateral hearing loss. For some patients, it can be caused by physical trauma or loud and excessive noise to the impaired ear. Yet for others, their loss is a result of various illnesses or infections. These can include:
• measles
• mumps
• meningitis
acoustic neuroma (tumor on the auditory nerve)
• labrynthitis (swelling of the labyrinth in the inner ear)
• mastoiditis (bacterial infection of the mastoid bone, which sits behind the ear)
• Meniere’s disease (disorder of the inner ear)

Many patients who experience unilateral hearing loss will also suffer from tinnitus (ghost beeps or ringing in the ears). Often, this type of loss is permanent.


So then, how can hearing loss or deafness in only one ear be treated? Treatment options will vary based on the cause of the sudden loss. Some doctors may recommend surgery or steroids if applicable. For some patients, a hearing aid or a CROS system (contralateral routing of signals) may be recommended. With a CROS system, the patient wears wireless devices in his/her ears and sound input from the impaired side will be routed to the normal hearing side. The patient will have audibility and awareness of sounds from the side of the impaired ear. Unfortunately, localization of sound will still be lacking.

We recommend seeking professional help in the case of any hearing loss. Sudden or unilateral hearing loss can indicate an emergency that requires immediate treatment from a medical doctor. When it comes to your hearing, it is always better to err on the side of caution.