Most of the time people present with a similar hearing loss in both ears. When the hearing loss is different on each side, we call that type of loss asymmetric. When one ear does not hear and the other ear hears normally, a unilateral hearing loss exists. This is referred to as single-sided deafness (SSD).

There are many reasons why single-sided deafness can occur. It may be congenital, meaning the person was born that way. Another cause may be due to a virus. This can happen at any time from childhood to adulthood. It can come on suddenly without warning. Single-sided deafness can also arise from a tumour or growth on the acoustic nerve or if there is damage to the nerve.

The affects of SSD vary from individual to individual; however, those with SSD often have difficulty hearing when there is background noise and struggle to localize a sound (determining where a sound is coming from). Often the sound is perceived as coming from the side with the better hearing, which is often incorrect. Other common complaints include reduced spatial awareness and an impaired understanding of speech. Individuals with SSD may not participate in social activities or may have insecurities with regards to conversation.

Fortunately, there are options for treating SSD. One popular option is a hearing aid specific to SSD known as a CROS system. CROS stands for Contralateral Routing of Signals. A transmitter, which acts as a microphone, is placed on the deaf ear. It sends a signal to the receiving ear (receiver), which is a normal, compatible hearing aid. Current CROS systems are wireless, which means the transmitter sends the signal (sound) to the receiver through various means, such as a near-field magnetic induction (NFMI). If the better hearing ear does have a degree of hearing loss, the receiving hearing aid can also amplify sound for that ear, while simultaneously receiving the signal from the transmitting (deaf) ear. This is known as a BiCROS system.

CROS systems have been shown to reduce listening effort, improve sound localization, and provide better speech understanding. The newest devices provide streaming to multiple devices, such as TV streamers, cell phones, and more. CROS systems are offered at various performance levels and price points.

Submitted by: Curt Culford, M.Cl.Sc. Aud, Reg. CASLPO Audiologist and Owner
Culford Family Hearing 102-10 Keith Ave. Collingwood  |  (705) 293-HEAR  |