Overcoming single sided deafness

Advancements in diagnosis and treatment for single sided deafness (SSD) mean great outcomes can be achieved. The work of audiologist DR DAYSE TÁVORA-VIEIRA has been pivotal in gaining regulatory approval for cochlear implants as a treatment for children and adults who are deaf in one ear.

And ROBYN SHAKES, MED-EL’s managing director for Australia, discusses MED-EL’s solutions.

When Dr Dayse Távora-Vieira began researching cochlear implants as treatment for single sided deafness (SSD) 17 years ago, her work challenged conventional thinking. Fortunately, the Perth audiologist was undeterred and progressed with her pioneering work that has helped change the landscape for this group of patients.

In that time, she has become a world-renowned expert in the field. She has also played a leading role in advancing cochlear implant care for SSD at Fiona Stanley Fremantle Hospitals Group including Fiona Stanley Hospital, plus Royal Perth Hospital and Sir Charles Gairdner Hospital, where she is the head of statewide tertiary audiology services.

“Our non-user rate remains below 5% and we are very proud of that,” she adds.

“The initial misconception was that there was no need to address the deaf ear if the other ear has normal hearing. It was also assumed that with natural hearing on one side, and a cochlear implant on the other, the brain wouldn’t be able to integrate the two signals.”

Dr Távora-Vieira, also Adjunct Associate Professor at the University of Western Australia and an Associate Professor at Curtin University, says that since the 1980s, studies have showed that unilateral hearing loss in children impacted their development by affecting school and academic performance, plus psychological, emotional and social development.

When researching tinnitus as a potential PhD topic, she came across a Belgium group trialling cochlear implants for tinnitus relief in patients with SSD.

“They were not looking at what the implant could do for hearing,” she recalls. “I started reading more about single sided deafness and realised its effects had been under-estimated for too long.

“My PhD question became, ‘What happens if we provide a cochlear implant to single sided deafness patients in terms of hearing?’.” Her PhD in adults with SSD investigated integrating the two signals, and whether people could hear using combined normal hearing and a cochlear implant.

“We found the improvement they were achieving was massive in terms of hearing; we proved that the brain can put the two signals together and their hearing and quality of life improve after hearing is restored on the deaf side,” she says.

TGA approval

Her team expanded the research and found that while people with long duration of deafness did well with the implant, it took longer to achieve the same outcome as those who were deaf for less time. Deafness onset was also important, with those losing hearing at a younger age faring worse than those with later onset who had a well-developed neural pathway pre-surgery.

In 2015 the Therapeutic Goods Administration (TGA) in Australia approved cochlear implants as SSD treatment.

“Our publications were the main body of literature for the TGA approval and we’re very proud of that,” Dr Távora-Vieira says. “A few years later, we were asked to provide evidence for US researchers to do a trial seeking FDA approval so we also laid the groundwork for approval in the US and later Europe.”

Different auditory training

The team has published more than 40 articles on SSD, including over 20 on understanding the role of symmetrical brain activation and the effect of mapping. It also developed an assessment and evaluation framework and guidelines for SSD rehabilitation.

While many countries have now approved cochlear implants as SSD treatment, Dr Távora-Vieira says not all fund it. In Australia, funding is state based, and not all public hospitals provide it, but private health insurance may cover it, she says. There are some exceptions for children.

Auditory training for single sided deafness is different from bilateral deafness, she explains.

“If a person is completely deaf, the brain has no reference point, but SSD is different because the brain compares one signal with another.

“If you don’t provide a reasonably good signal, the brain will likely ignore it. We did studies using EEG looking at how the brain processes the signal when providing two different inputs and we use that to create a protocol to program the implant.”

Dr Távora-Vieira says that poor outcomes in SSD can be due to programming deficiencies. “People with SSD have different needs because the brain has a reference point that’s normal hearing, so you need to work on providing a symmetrical signal to the brain to make it easier for the brain to integrate the two signals,” she adds.

“SSD cannot be looked after the same way we look after bilateral deafness. And this might be why some become non-users of an implant along with other reasons such as traumatic surgery, partial electrode insertion or patients not willing to commit to rehabilitation. If we cannot make hearing symmetrical, patients may become non-users.”

Mapping the implant more accurately by brain activity with evoked potential equipment available in many larger clinics or hospitals provides immediate improvement, she says.

Rehabilitation is also vital and requires a structured program where patients actively teach the brain to recognise the sound. This is different from bilateral deafness where daily life is training, she adds. “If you don’t actively train the implanted ear, the brain will give preference to the normal hearing ear,” she adds.

Impacts of unilateral hearing loss

The reported incidence of congenital SSD is 1:1000 births,  and among adults, SSD prevalence is estimated at about 0.14%, Dr Távora-Vieira says. Studies have shown that almost half of newborns with SSD have no auditory nerve so are ineligible for cochlear implants. But the other half do, and CI is an option

At Fiona Stanley Hospital, children and adults with SSD can receive cochlear implants.

“When everything comes through one ear, the brain can’t separate the signal from the noise,” she says. “With binaural hearing you can localise sound, you know where sound’s coming from and hear much better in noise because the brain filters out what you don’t want and concentrates on the signal you want.”

People with SSD say they don’t need help hearing in quiet settings but as soon as they are in noise they struggle, she adds. “Over and over again we see people aged in their 30s who think they can cope come back in their 40s wanting the surgery,” Dr Távora-Vieira says.

“When you’re younger, you create coping strategies but that diminishes with age.

“Teens often return in their 20s seeking an implant when they’re working, studying, or have children and are struggling to cope in noise. 

“As soon as the environment is more challenging, they struggle.”

Older adults return seeking help after they become fatigued and exhausted from trying to concentrate in noise for years, she adds.

Dr Távora-Vieira urges audiologists to refer these patients to their local implant clinic with experience in SSD. 

Audiologist Ms Robyn Shakes, MED-EL’s managing director for Australia, says its OTOPLAN software for individualised implantation and 3D visualisation plus anatomy-based fitting are key advancements in the field.

“One of the big differences with our cochlear implants is that they’re individualised. We have a large variety of electrode array lengths to best fit the various cochlear duct lengths in individuals,” she says. “Our OTOPLAN software uses the pre-surgery MRI or CT scans to measure the cochlear duct length giving valuable information to surgeons.

“The MED-EL speech encoding strategies have evolved over time as we continue to learn more about the processes involved with the normally hearing ear. We attempt to get as close as possible to Natural Hearing with our individualised electrode array selection, our Fine Structure Processing (speech coding strategy) and our Anatomy Based Fitting (technology).

“These enhance the temporal aspects of hearing that are so important for natural pitch matching, hearing in noise and sound localisation.”

Shakes says adults with SSD are aware of its debilitating effects and challenges that they face include fatigue, poor sound localisation and difficulty in social situations.

Children struggle in school

Research shows children with SSD can struggle in school and are more likely to repeat a year, she adds. “It’s an invisible disability that can affect social interactions and scholastic achievement. Early intervention and counselling are very important.

“Some patients try hearing aids first while others go straight to a cochlear implant depending on degree and aetiology of the hearing loss,” she says.

“We’ve known for a long time of people born with single sided hearing loss and others who gradually or suddenly lost their hearing in one ear. Until relatively recently there were not many options for treatment.”

Adults who were born deaf might not have developed auditory pathways so they might be unsuitable for a cochlear implant. But if people develop hearing loss later in life, it’s generally not that difficult to reignite their existing pathways, Shakes says. “Those patients particularly do well with cochlear implants for bilateral or single sided deafness.”

Children born deaf in Australia are identified during newborn screening. “We need to make cochlear implants available to these children while those auditory pathways are being laid down, just as we do for children born deaf in both ears,” she says.

She says the first cochlear implants for SSD in Belgium showed significant unexpected benefits such as improved hearing in background noise and better directionality. “The initial intent was to relieve unbearable tinnitus by amplifying background outside noise.

“The amazing by-product was they could hear speech – it didn’t just abate the tinnitus,” Shakes says. “Recipients were getting really good hearing too, very good outcomes quickly. It was quite miraculous.”

Outstanding results

Similarly, Dr Távora-Vieira’s group has had outstanding results with more than 95% being full-time wearers of their sound processor, leading the way worldwide, Shakes adds.

She says audiologists have an important role in identifying candidates who may benefit from cochlear implants for SSD.

“There’s growing awareness that we can do something for adults and children with single sided deafness and they can achieve excellent results. But more awareness is required for candidates that there is a solution, and among professionals that it is worth referring them for an assessment,” Shakes says.

MED-EL runs workshops and has resources for audiologists to learn about cochlear implants for SSD, and patient resources including its free ReDi app to practise auditory and speech skills.

Practitioners can email help@medel.com.au for advice on patients. See also MED-EL.

Solutions for single sided deafness online symposium

An expert-led MED-EL Australasia online symposium on 30 October 2025 will cover solutions for single sided deafness. Attendees will discover the latest advancements and clinical best practices in treating SSD.

The session brings together leading experts in the field to share surgical insights, programming strategies and research updates that are shaping the future of SSD care.