Portrait and video Johan Frijns: “When a deaf child suddenly hears and learns to talk, this also has a huge impact on the people around him.”

Thursday, February 15, 2024

More than 800,000 people in the Netherlands are hard of hearing. They suffer so much from hearing loss that it limits their daily lives. Prof. Dr. ir. Johan Frijns treats people with hearing loss, conducts research on hearing implants, and gladly shares his knowledge about electrical stimulation of the nervous system. "We shouldn't want to reinvent everything in every little corner. What we learn in one place, we can also use in another."

Johan Frijns is a professor of Otology and Physics of Hearing in the Department of Otorhinolaryngology at LUMC. He heads the Center for Audiology and Hearing Implants Leiden (CAHIL) and the Cochlear Implant Rehabilitation Centre Leiden (CIRCLE). He was recently appointed as a Medical Delta professor with a position at the Faculty of Electrical Engineering, Mathematics, and Computer Science at TU Delft.


You have been appointed as a Medical Delta professor. What does that mean for you?

"For me, it means going back to my roots. Almost 40 years ago, I graduated as a physicist from TU Delft. I have always maintained contact with and supervised students in Delft. That is how I became involved in the Clinical Technology and Technical Medicine programs. 'Because you embody technical medicine,' said my dean at LUMC. Now, this has been formalized, and I find it extremely exciting.

I am not sure if much will change now. I already collaborate a lot with Wouter Serdijn's Bioelectronics department in Delft. We have several ongoing projects and have made new plans. Together with him, I am part of NeurotechNL, an initiative from the Royal Netherlands Academy of Arts and Sciences (KNAW). This led to major projects where we regularly encounter each other. What I hope Medical Delta brings me is easier accessibility and the ability to reach others more easily."

Can you briefly explain what your expertise is?

"As an ear surgeon and head of the LUMC expert center for rare ear diseases, I treat people with hearing loss. In addition to my surgical work, I research hearing implants that electrically stimulate the auditory nerve or brainstem.

Currently, many deaf and severely hearing-impaired individuals can benefit from electrical inner ear prostheses, also known as cochlear implants or CIs. With these implants, they can recognize sounds and speech. Adults are better able to communicate with the outside world because of this. In children, CIs can facilitate the development of spoken language, enabling them to often attend regular education after treatment. This makes an enormous difference for someone.

In children, CIs can facilitate the development of spoken language, enabling them to often attend regular education after treatment. This makes an enormous difference for someone.However, CIs also have significant limitations. The devices do not always transmit detailed timing information of a sound to the auditory nerve effectively. As a result, CI users struggle to separate speech sounds from background noise, perceive direction, appreciate music, or distinguish different voices.

In a project with Health~Holland, we are working on a CI model that closely mimics natural hearing. We are using a previously developed computer model of the electrically implanted inner ear, expanded with a simulated CI speech processor. The computer model is linked to a model of natural hearing. Both models produce nerve impulses. Using machine learning and artificial intelligence, the CI speech processor is adjusted to mimic the nerve impulses of normal hearing as closely as possible.

In my work, I also examine the social development of deaf and hard-of-hearing individuals. For example, we are researching the employment participation of CI users compared to hearing aid users and normal-hearing individuals. How much effort does it take, and how do they feel at the end of the workday?

Being born deaf has a significant impact on your psyche. But research shows that children with CIs are mentally close to the group of normally hearing children, compared to hearing-impaired children who use hearing aids. We want to bring the latter group closer to that level too. It seems like hearing-impaired individuals are socially approached much more negatively than deaf individuals.

Additionally, we use imaging techniques to investigate how to insert an electrode with minimal damage. The previous version of the electrode was inserted within 10 seconds to prevent resistance. With a new, much thinner electrode, we have slowed down the insertion process. What we found was that if you take longer than 25 seconds to insert it, the chance of the electrode going into the wrong chamber of the cochlea is much smaller. Due to this new insight, there is now two-thirds less damage during insertion."

How can you apply your expertise more broadly?

"A lot of knowledge has been gained in the past twenty years with cochlear implants, which we can use to shorten the learning curve for other forms of electrical stimulation. Things are happening there that have already been tried for CIs and I wonder how promising they are. We should not reinvent everything in every silo. What we learn in one place, we can also apply elsewhere."

How do you ensure a smooth transition from the non-hearing to the hearing world?

"In Leiden, patients receive extensive hearing training. Initially, twice a day under the guidance of a speech therapist. They do this together with a partner or a close friend who continues practicing with them at home. Social work is also involved. Being able to hear again and learning to speak as a deaf child has a massive impact, also for the surroundings.

Being able to hear again and learning to speak as a deaf child has a massive impact, also for the surroundingsThere was a girl who was deaf and blind due to her condition. She could only communicate with her mother by holding each other's hands and moving them in gestures. After receiving an implant, the girl could do more things independently again. It was the mother who, although she was incredibly happy with this result, had to get used to her daughter not being so dependent on her anymore. There are also relatively many divorces among parents of children who get a CI. But we also know incredibly happy CI couples who met each other in the waiting room.

We have also conducted research into the socio-economic impact of a CI operation. An expensive procedure at € 50,000 per ear. We have listed all costs and benefits. The procedure, maintenance, the influence on education and work. When you calculate everything, it turns out that if you give a child two CIs at the age of one, it yields a net value of € 430,000 in terms of quality of life and economic aspects. That is a huge impact on someone's life and society."

What do you hope to achieve for the patient in five years?

"My idea is to make a CI user hear normally, but unfortunately, that won't be achievable in five years. What I do hope to achieve significant improvements in is music perception. CI users cannot listen to music the way we do. They must practice intensively to recognize music again, and some of them lose their ability to perceive music forever. One of my patients was 1.5 years old when he received a CI. He found a way to listen to music well by himself. As a teenager, he became a DJ, and now he is doing a professional dance education. I have a lot of admiration for that perseverance.

I also want to make significant strides in making speech more understandable in demanding situations. With a CI, it is difficult to distinguish between a male or female voice or to hear nuances. A sentence can be a question or statement depending on the intonation. For a CI user, that is not audible. It should be possible to improve on that."

How do you involve practical partners in your research?

"As an ear surgeon, I treat patients myself, and in our research, we collaborate with patient associations for CI users and deaf and hard-of-hearing individuals. We present every grant application to them, and they also help with finding test subjects. They are also critical and sometimes say, 'Great for you as researchers, but what's in it for us?'.

Patient input is important. One example is various smart microphone techniques that automatically switch. Based on the signals picked up by the CI, the device analyzes the environment and adjusts the program accordingly. That seems smart, but better CI users find it annoying. Because useful background signals - someone entering the room, for example - are also filtered out. Then you get feedback like, 'Turn it off for me because it's driving me crazy.' We no longer activate this as a standard for everyone.

I have my office in their department and not with ENT colleagues on another floor. That is a deliberate choice. They are an important link to the practice for me.The question is what the user wants. Sound quality and speech intelligibility are sometimes conflicting. Amplifying high frequencies is important for understanding conversations but often unpleasant for sound perception. Clinical physicists/audiologists sometimes really must push patients to try it anyway.

Clinical physicists/audiologists are my daily colleagues. I have my office in their department and not with ENT colleagues on another floor. That is a deliberate choice. They are an important link to the practice for me."

What is it like to start collaborating with someone from a completely different discipline?

"I gradually grew into it. As a student, I first studied physics for three years, and in the final year, I started medicine simultaneously. That is when I noticed that doctors think very differently. One example is how outcomes are interpreted. Once something is incorrect, it remains incorrect in technology. In medicine, it is about what occurs most often.

It helps me that I know how my colleagues think and that I already work with many different disciplines within the ENT department. In addition to ENT surgeons and nurses, also with audiologists, electrical engineers, speech therapists, psychologists, social workers, and radiologists: the department is very multidisciplinary.

Collaborating with people at TU Delft is extremely easy. There is a natural interest, but technology push arises quickly, and you want to prevent that. You also need each other's expertise. Together with Wouter Serdijn, I supervised a PhD student working on low-power electronics. She wanted to develop an analog low-power CI processor. But that does not work in practice. You want to be able to adjust the CI, and that requires energy. Therefore, the knowledge from practice is very important, and I hope I can contribute that in Delft."

What is missing in the collaborations within Medical Delta? What message do you want to convey?

"I notice that Medical Delta is still not very alive in Leiden. We know the people, but it does not feel like something the average medical specialist wants to be part of. It remains with a few enthusiasts, and I am not sure yet how to change that. The same goes for the Technical Medicine program. We now have two graduates from Twente and one from Delft walking around, and the people collaborating with them are enthusiastic. They notice they can do things we cannot.

'They're doing very clever things in Delft, but we don't understand that' is what some thinkIf you are not a medical specialist, it takes longer to be seen as a full-fledged conversation partner. 'We specialists know better,' still lives strongly with some. And sometimes it is also the unknown. 'They're doing very clever things in Delft, but we don't understand that' is what some think. I had a colleague who could perform the most complicated surgeries but could not repair a plug at home. You just have to be open to it and also dare to walk into each other's offices."

Which other scientist has surprised you or put you on a different track?

"In my younger years, I was put on a different track by John Laird, professor of physiology in Leiden. I was sixteen and had the idea that I wanted to study medical technology. But there was no such program then. So, I called him to ask if I could come by. He turned out to be originally an aeronautical engineer. He told me that you can see science as a large cabinet with drawers. As a medical student, you learn to know each drawer one by one, but you do not learn how to build a new drawer. He advised me to first study something technical and medicine afterward. So, I started with physics at TU Delft first."

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