Please read Part 1 of this article to learn more about unilateral hearing loss a.k.a. hearing loss in one ear

Essentially, unilateral hearing loss is characterised as a condition in which one ear has hearing loss while the other ear has normal hearing. This is in contrast to bilateral hearing loss where hearing loss is diagnosed in both ears. Prior to treatment, a complete hearing assessment must be carried out to determine the level and type of hearing loss. Typically, an audiologist will conduct the hearing test and then, customise the aural rehabilitation plan for each patient.

Up until today, there is no known cure for permanent hearing loss. But while there is no cure, there are treatments such as aural rehabilitation that can help people with hearing loss hear clearly again. Hearing aids, communication strategies, auditory training and therapy are often employed as part of the aural rehabilitation journey. This is why most people with bilateral hearing loss, or hearing loss in both ears, are prescribed hearing aids. But before the hearing aids can be worn, it needs to be programmed according to the hearing levels in each ear. This ensures that the hearing aid is providing the right amount of sound for each ear so that users can hear clearly and avoid further damage to their hearing. Hearing aids work by amplifying sounds that are difficult to hear to provide better detection and understanding of speech, music and environmental sounds. Being able to listen to these sounds helps a person with hearing loss keep in touch with family members, communicate with friends, indulge in their favourite hobbies such as watching the tv and reduces the risks of depression or anxiety. 

Similar to bilateral hearing loss, the first line of treatment for unilateral hearing loss is a hearing aid. Unlike bilateral hearing loss which requires two hearing aids, a patient with unilateral hearing loss can benefit from just one hearing aid. However, if the loss of hearing in the affected ear is severe, they may not be able to hear clearly in that ear even with the help of a hearing aid. This condition is known as single-sided deafness (SSD). Single-sided deafness (SSD) is a more extreme version of unilateral hearing loss where people experience such a tremendous drop in hearing that even a traditional hearing aid is unable to provide enough amplification in the affected ear. 

A common problem faced by people with SSD is that they cannot hear clearly when someone is speaking on their deaf side. This is due to the head-shadow effect where the head blocks some sounds from reaching the normal hearing ear. When the normal hearing ear cannot receive the full spectrum of sounds from the deaf side, it makes conversations difficult to understand. The head-shadow effect can be mitigated with Contralateral Routing of Signal (CROS) hearing aids. CROS hearing aids consist of two devices: (1) a microphone worn on the deaf ear, which picks up sounds coming from the region of space facing the deaf ear and (2) a receiver which receives the sounds wirelessly from the microphone and passes it to the normal hearing ear. The transfer of sounds from the microphone to the receiver ensures that the normal hearing ear can detect sounds from the direction of the deaf ear, thus overcoming the head-shadow effect. Unfortunately, CROS cannot restore hearing in the deaf ear. While it might sound counterintuitive, this technology has actually been proven to improve awareness of sounds coming from the deaf side and help individuals better understand conversations in noisy environments.

Another option for people with SSD is the use of bone conduction hearing aids. A bone conduction hearing aid is a small device worn behind the deaf ear, and creates vibrations in response to sound. These vibrations travel through the skull from the deaf side to the normal hearing ear, thus allowing individuals to detect sound originating from the direction of their deaf side. Bone conduction hearing aids show a lot of promise as it can be used by individuals with physical malformation in the ear and chronic ear discharge; conditions which do not permit the use of CROS hearing aids.

The nuclear option in our arsenal to help people with SSD is a cochlear implant. Cochlear implants are high-tech medical grade devices that need to be surgically implanted by an ENT in the deaf ear. Cochlear implants will receive sounds from the environment and use it to stimulate the auditory nerve, bypassing the deaf ear entirely. The auditory nerve then carries the signal to the brain which results in the perception of sound and speech. Cochlear implants offer a remarkable benefit which is, it can potentially help the deaf ear hear again. So, a person who is deaf in one ear may prefer cochlear implants over other treatments if their goal is to hear in both ears.

Single-sided deafness can significantly impact an individual's ability to fully participate in activities and communicate effectively. Consult an audiologist today as they can determine the most suitable treatment for an individual's specific needs. They will evaluate the severity of the hearing loss, the cause, and the patient's preferences to make an accurate recommendation. With the advancements in technology, treatments such as CROS hearing aids, bone conduction hearing aids and cochlear implants continue to offer hope for individuals with single-sided deafness, allowing them to regain their ability to engage in conversations, and improve their overall quality of life.

Patrick Seow, Clinical Audiologist at 20dB Hearing