Single-sided deafness (SSD), also known as unilateral deafness, is a type of hearing loss where the person has normal hearing in one ear but significant hearing loss, or no hearing at all, in the other ear.
Common causes of single-sided deafness in adults include acoustic neuroma, sudden idiopathic hearing loss, exposure to sudden impact noise, head trauma/traumatic brain injury (TBI) and Meniere's disease.
Acoustic neuroma
An acoustic neuroma is a slow-growing, noncancerous tumor, that develops on the main nerve that connects the inner ear to the brain. The nerve has two branches; one branch influences balance, and the other transmits hearing. Some of the symptoms of an acoustic neuroma include hearing loss in one ear accompanied by ear fullness and ringing noises (tinnitus) in the same ear, unsteadiness, facial numbness and mental confusion. As the tumor grows it can become life threatening. Treatment to remove the tumor often results in SSD.
Sudden idiopathic
hearing loss
Sudden idiopathic hearing loss is usually caused by a viral infection, although sometimes the cause is unknown. The virus normally infects the cochlea, causing localized swelling, resulting in sudden permanent damage to the inner structures of the cochlea. The patient is normally left without any hearing in one ear.
Exposure to sudden impact noise
Noise exposure remains a huge public health problem. However, exposure to high levels of sudden impact noise without noise protection is detrimental to good hearing. For example, just a single shot from a large caliber gun at close range, or a loud explosion closer to one ear, can cause SSD. The most common signs of possible hearing loss due to sudden impact noise exposure are tinnitus accompanied by sudden hearing loss.
Head trauma/traumatic brain injury
Blunt trauma to the head, or the occurrence of unilateral vascular insults might result in damage to the temporal bone, the vascular structures in the brainstem, or to the cochlea, damaging the auditory pathway causing SSD.
Meniere's disease
Meniere's disease occurs when excess fluid pressure in the ear produces longterm damage to the cochlea. Symptoms of Meniere's disease typically occur on one side only, and include a roaring tinnitus, a feeling of ear pressure or pain, hearing loss that comes and goes, and severe vertigo.
The effects of single-sided deafness in adults can include the following symptoms:
Localization and spatial hearing
There are specific cues in our two-ear input auditory system that allow us to orient and localize sound. If there is damage to the hearing in one ear, confusion relating to spatial orientation and the direction the sound is coming from will occur. Persons with SSD may often respond to sound or speech by turning in the opposite direction from where the sound source originated.
Head-shadow effect
This occurs when speech presented at the poor ear is forced to cross over the head to the opposite side, so that it can be heard by the good ear. The head-shadow effect causes persons with SSD to have difficulty understanding speech when background noise is present, creating significant communication problems for them in places like restaurants, bars or at a party, etc.
Binaural summation
There is a saying, "Two ears are better than one", and we see this played out in binaural summation, which is the auditory boost we receive when both ears are functioning properly and hear sounds equally well. Binaural summation results in easier listening and an improvement in word recognition. Persons with SSD may frequently misunderstand what is said, particularly soft-spoken speech. They also tend to tire more easily, as so much effort is exerted with trying to listen all day.

Communicating with a person who has SSD
The following tips can help improve your ability to communicate with someone who has single-sided deafness:
o Always speak closest to the better ear.
o Avoid places that are noisy; find a quiet spot when in restaurants, etc.
o Always face the person with SSD. If they cannot see you, they probably cannot hear you well.
o Avoid speaking to them from another room.
o Do not turn your back or walk away while speaking.
o Always speak clearly. Avoid mumbling or whispering; practice speaking in a normal, clear voice.
o Avoid dark places or "mood lighting". The person with SSD will understand you much better in a well-lit environment, where they can see your facial expressions, lip movement and body gestures.
o Reduce or eliminate background noises like TVs, radios, fans and air-conditioning, as these can drown out the conversation.
o When communicating with a person with SSD in a car, arrange seating, if possible so that their good ear is nearer to you. Keep the radio/music turned off to help them hear you better. Remember, even engine noise and noisy traffic can make it difficult for them to follow the conversation.
o Avoid putting your hands over your mouth, smoking and chewing when speaking to a person with SSD. Your face and lips should always be visible to the person with a hearing loss, as it gives them crucial clues regarding what is being said.
o Keep moustaches and beards trimmed, as they hide the lips, making it difficult for a person with SSD to follow a conversation.

Hearing aid help for
unilateral hearing loss
In addition to the above communication tips, a person with SSD may also receive significant help communicating by using a CROS hearing aid or bone-anchored hearing aid (BAHA).
A CROS hearing aid is specifically designed for persons with single-sided deafness. A microphone that resembles a hearing aid is placed on the deaf ear. The acoustic signal picked up by the microphone is then routed to an amplifier that is placed on the good ear. The sound that is heard at the deaf ear is then contralaterally sent over to the good ear, allowing the person with SSD to have the perception of hearing on the poorer side.
A bone-anchored hearing aid (BAHA) is another device option for persons with SSD. The BAHA is a surgically implanted hearing system that works by directly transferring sounds through bone vibration to the cochlea, bypassing the outer and middle ear. Single-sided deafness affects not only listening and communicating, but also quality of life.

o For further information on any hearing-related disorder, please contact Dr. Deborah Nubirth, doctor of audiology, at 356-2276 or 677-6627 in New Providence at Comprehensive Family Medical Clinic, Poinciana Drive or 351-7902 in Grand Bahama; or email dnubirth@yahoo.com.

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