Background
With an aging population, the number of people with poor hearing is on the rise. Consequently, hearing is an important field of research, and the demand for well-developed hearing aids is increasing. The Linnaeus Centre HEAD*, a multidisciplinary centre for hearing disabilities and deafness, conducts research into cognitive hearing science. Together with other LiU researchers, Jerker Rönnberg, professor of psychology and director of the centre, has built up and advanced this interdisciplinary research field.
Cognitive hearing science investigates how people with deafness or hearing impairment develop their cognitive resources in order to communicate in everyday situations. For instance, the brain must work hard for them to hear speech in noisy environments.
Jerker Rönnberg. Photo credit David Einar“The entire perspective shifted when we started to talk about cognitive hearing science, and not only hearing science. We hear with the ear, but listen with the brain”, says Jerker Rönnberg.
The field of cognition includes the brain’s working memory and long-term memory. The better our working memory, the easier it is for us to interpret and combine bits of information to meaningful units, such as parts of words or sentences that we understand. But when the working memory starts to fail, a greater mental effort is required. People with hearing loss have to strain their working and long-term memory much more than people with normal hearing, for instance in places with lots of noise and buzzing.
Impaired hearing can lead to worsened long-term memory. The working memory retains its activity and is “exercised”. But parts of the information do not reach the long-term memory because of the hearing impairment, and then the long-term memory is not activated the same way; it doesn’t get as much “exercise”. If you don’t hear well, you store less information in your long-term memory and you do not retrieve information from there as often. If the long-term memory is not used, it deteriorates – and worsened long-term memory can increase the risk of dementia.
“This shows that it can be important to get help with your hearing aid as early as possible, including just to prevent memory deterioration and dementia”, says Jerker Rönnberg.
Collaboration
In cognitive hearing science it’s necessary to collaborate with other fields, both over faculty borders and with other universities. At LiU, an interdisciplinary collaboration is under way between the faculties of engineering, humanities and medical sciences. Moreover there is collaboration with other universities, both nationally and internationally, including Örebro and Lund universities, as well as universities in Canada and the United States, and through several EU-funded collaborations, including with universities in the Netherlands.
Also noteworthy is the extensive industrial collaboration, in particular with the Danish company Oticon, a world leader in hearing technology. Thomas Lunner, originally an engineering student at LiU, is now head of research at Oticon and a part-time professor in cognitive hearing science at LiU.
Photo credit Anna Nilsen
“The combination of having one foot in the business sector and the other in academia means that high-quality research can immediately be implemented in the development of hearing aids”, says Thomas Lunner.
Collaborations are also ongoing with other businesses in hearing technology, including from Australia, and with hospital clinics and organisations such as the Swedish Association of Hard of Hearing People, Swedish Association of the Deaf, and National Agency for Special Needs Education and Schools.
Operations and results
The Linnaeus Centre HEAD for cognitive hearing science is primarily a collaboration between the Swedish Institute for Disability Research at the Department of Behavioural Sciences and Learning, and Technical Audiology at the Department of Clinical and Experimental Medicine, at Linköping University. The research has been under way since 2008. Since then, approximately one thousand scientific research articles have been published. Several of these were groundbreaking, and LiU is a world leader in the field of cognitive hearing science**. The HEAD Graduate School has been built up, and some 40 doctoral theses are affiliated with it. Five international conferences have been held, and research funding comes from organisations such as the Swedish Research Council, FAS and the EU.
The ELU model (Ease-of-Language Understanding) has been developed, and forms the foundation for the continued improvement of hearing aids. The model investigates how working memory capacity, attention and other functions interact with episodic and semantic long-term memory in listening situations that are easy, as well as in noisy situations where the person’s concentration and understanding are challenged.
The research and collaboration have led to, inter alia, the following results:
- Improved hearing aids for tens of millions of people worldwide
- Tests that measure new functions of hearing
- Studies that indicate a certain correlation between hearing loss and a shrinking brain in the areas related to cognitive functions
- Studies that indicate a certain correlation between hearing loss, worsened cognition and dementia development
There are also plans at LiU to start a three-year audiology programme with a special focus on cognition.
It is highly probable that within ten years, technology will have taken another big leap forward. Through testing at Oticon and by scientists in cognitive hearing, researchers are working to develop a technology where the eyes and brain can guide the sound in a direction that helps people with hearing impairment. This is done using electrodes connected to the hearing aid. If for instance a person with poor hearing wants to listen to someone sitting to their left at a dinner, they can use eye movements to guide the sound, so that person’s voice becomes clearer than the ambient noise.
“The guiding of sound will be a feature in the hearing aid of the future. In the long term, one consequence of the continuing development of hearing technology will be a better quality of life for people with hearing impairment, for instance reduced social insulation, fewer depressions and reduced risk of dementia”, predicts Thomas Lunner.
* The Linnaeus Centre HEAD (Hearing and Deafness) is a collaboration between Linköping, Örebro and Lund universities. The centre consists of several interdisciplinary research teams in the field of hearing loss and deafness.
** An example of a current, world-leading scientific article is Cognitive hearing science and ease of language understanding in the International Journal of Audiology, February 2019 https://doi.org/10.1080/14992027.2018.1551631