Our eyes and ears are more connected than we think

We know your pupils dilate when you invest effort into listening. The unanswered question is, what can we use that knowledge for? Our researchers Dorothea Wendt (Research Engineer, PhD), Thomas Lunner (Senior Scientist, Professor, PhD) and Renskje K. Hietkamp (Clinical Researcher, MA, Audiology), have been doing pupillometry research for the past few years. This has included multiple degrees of training sessions, and close co-operation with prof. dr. Sophia E. Kramer, from the VU university medical center in Amsterdam. The results are finally here; and they could redefine audiology research going forward. 

This week, Dorothea Wendt, went to the AAA conference in Phoenix to present our results, and to demo the effects of pupil dilation under listening effort. This is a big step, not just for us, but for the world of audiology, towards building hearing aids that are much more user-friendly, and gives less cognitive load to the brain. For the first time ever, we show how – in comparison with previous technology, or an identical set without this feature – new hearing aid signal processing like the MSAT actually reduce listening effort as measured by pupillometry. 

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Our research began with the project “LISTEN;” An EU funded Marie Curie Industrial Training Network program, and a partnership between VU university medical center in Amsterdam and Eriksholm Research Centre. Our research group built on top of the expertise in pupillometry, developed by dr. Sophia E. Kramer, Professor in Auditory Functioning and Participation at the dept. of Otolaryngology-Head and Neck Surgery, section Ear & Hearing at the VU university medical center; a project which Thomas Lunner and Barbara Ohlenforst also worked on. 

What Amsterdam found in the “LISTEN” project, is that when we pay attention to sound, the muscles in our eyes contract and release; effectively dilating based on our listening effort. The more effort we put into listening, the larger our pupils grow. This led our team to the groundbreaking discovery that we can use the dilation of your eyes to improve our understanding of hearing aid signal processing in relation to listening effort; in other words, to better understand how we process sound, how we can ease the burden for a user, and how we can provide a more natural-sounding experience, by – somewhat – using your eyes as windows to your soul.  

After a long training period, and a long stay in Amsterdam, working out of the VU University Medical Center, the research spawned the expanded project “LISTEN+”, spearheaded by Dorothea Wendt, Thomas Lunner, and Renskje K. Hietkamp. It is that project, “LISTEN+” that went on to make this groundbreaking discovery in audiological science, regarding hearing aid signal processing.   
Traditionally, audiology has been a very audio-centric research field. However, with these new results, we have a direct way of measuring the strain on our brains’ processing power in different situations. These results have been used in a number of areas, perhaps most notably in the way we research hearing loss.

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For example, we can now directly determine whether a lot of background noise, or even a specific kind of background noise, is more straining on our cognitive load than other kinds. We can also test a number of - for example - noise-reduction technologies and determine not only which one works best for the fragile hairs in our ears, but also which technology provides the most life-like sound spectrum; essentially the technology that saves the most mental processing power. 

In the future, we can employ this technology to resolve some of our time’s biggest audiological challenges; how do we perceive our own voice through hearing aids? How do we counter-act the experience of having your ears closed off? How do we decrease the strain on the mental processing plant when using hearing aids to – ultimately – normal?