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World's first ever long-term study on hearing ability in noise

VU University Medical Center Amsterdam: a leading-edge research hubAt Amsterdam's VU University Medical Center Sonova sponsors a research project that is unique in the world. This long-term cohort study, already in progress for almost ten years, investigates the hearing ability of people in various age groups. The focus is on examining the psychosocial consequences of hearing loss – and the first results break new ground.  

With a total of twelve faculties and some 24,000 students, the VU University numbers among Europe's most renowned research institutes. Even the physical size of this university is impressive: taken together, all the sites occupy an area of over 370,000 m².

To reach her workplace at the VU University Medical Center, Mariska Stam has to pass through long corridors as well as use an elevator and several staircases that connect different floors. "I always meet visitors at reception, otherwise they'd never find their way to me," this 27-year-old PhD student jokes. She is a member of a unique research project that Sonova has sponsored since September 2010. Stam brims with enthusiasm as she talks about her work: "I can't imagine a more interesting job."

Stam joined Professor Sophia Kramer's research group embedded in the EMGO Institute for Health and Care Research at VU University Medical Center in Amsterdam back in 2010. This is one of the world's leading institutions in the field of hearing research. The project on which Stam works is unique: the "Netherlands Longitudinal Study on Hearing" (NL-SH) is a long-term cohort study that aims to analyze the hearing ability of individuals in different age groups. It examines the psychosocial consequences of hearing loss and shows the extent to which people with hearing problems are integrated into society, and what kind of difficulties they experience. The results provide the basis for more extensive studies focusing on diagnostics and new technologies. The international research community has already welcomed the first results, which have been used in scientific publications in countries such as the USA, Canada, Germany and the UK. 

A decade of research work

Several thousand respondents were questioned. Both adults with and without hearing loss are participating, providing the opportunity to study changes in hearing status over time. The schedule calls for three surveys, the first two already took place in 2006 and 2011, and the third is planned for 2016. The respondents are aged from 18 to 70 at the start of the study. They can enroll themselves into the study and then answer the 200 questions and complete the hearing test online in their own homes.

Direct collaboration and close partnerships with leading-edge international research institutes are intrinsic to our corporate culture

Ulrike Lemke, Senior Researcher in Sonova's Science & Technology department

"Direct collaboration and close partnerships with leading-edge international research institutes are intrinsic to our corporate culture," says Ulrike Lemke, Senior Researcher in Sonova's Science & Technology department, who is responsible for coordinating research projects. "We're particularly interested in understanding early symptoms of hearing impairment and the way they progress; we also want to learn about the concerns and needs of individuals who are affected, and we'd like to know more about how younger and older people make use of hearing aids. Once we are aware of needs and expectations – or can even predict them – we can improve the care process and offer even better hearing solutions. This long-term study will help achieve those goals."



Groundbreaking results

The first two surveys have yielded some highly promising results. Researchers Kramer and Stam discovered that individuals with poorer understanding of speech-in-noise encounter more problems in finding a job. Furthermore, they are usually less well educated and their incomes are lower. "The sense of loneliness is also a huge problem, especially for young people and older individuals with hearing problems," Professor Kramer points out. In the 50-60 age group, however, depressive tendencies pose the primary problem and loneliness is no longer the prime concern. "People's perception of their own situation changes during this phase of life. We need to undertake more studies on this!"

The key question for our healthcare system is: at what age should we have our hearing tested? Data from our study will provide an answer.

Sophia Kramer, Professor

The amount of research undertaken into hearing is still insufficient, as compared to vision. "For instance, an optician can more or less predict the age when you'll need eyeglasses, or when you'll require stronger lenses for your reading glasses," Professor Kramer explains. "We use what are known as trend curves to guide us when assessing levels of hearing ability in different age groups. However, the database for these curves is meager, so the information available is very vague at best. The key question for our healthcare system is: at what age should we have our hearing tested? Data from our study will provide an answer." The hearing ability of respondents in the longitudinal study deteriorated by 0.4 dB during the first five years. But not all age groups are impacted equally, the professor notes: "Up to age 50, the change is linear but then a sudden deterioration sets in. This happens earlier than was expected, and it affects people in the middle of their working lives. We didn't anticipate that!"

Ongoing collaboration

Which medical conditions affect the respondents? Participants in the study were also asked about this. PhD student Stam and Sonova researcher Lemke were especially interested in respondents with multiple conditions. "There are indications of a link between vertigo and hearing problems, and also between diabetes and impaired hearing. Moreover, we believe that medication affects hearing ability, for example in case of diabetes," Stam explains. "We need to do more research here: what links are there between conditions that occur simultaneously? What are the underlying mechanisms?" Lemke adds: "In practical hearing loss care, another key priority is to discover how important hearing impairment is to an individual, and to be aware of additional issues that could impede the use of hearing instruments – such as difficulties with vision or sensory problems."

I believe that applied research projects such as this one can yield important data and help us optimize the progression of treatment for the psychosocial consequences of hearing loss.

Mariska Stam, PhD student

Sonova is also sponsoring the third phase of the long-term study project (2015-2018), which will include the next survey of participants. This will mean even closer contact and more interchange between Sonova's Science & Technology department and VU University Medical Center in the years ahead. In January 2015, a new PhD student joined the project team alongside Professor Kramer and Mariska Stam. Stam herself has already paid two visits to Sonova's corporate headquarters on the shores of Lake Zurich. "These were fantastic experiences! It's very interesting to view my questions and research hypotheses in the context of developments that are currently underway in the hearing instrument sector," Stam comments. "And conversely, I believe that applied research projects such as this one can yield important data and help us optimize the progression of treatment for the psychosocial consequences of hearing loss."


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