Research Engineer, Research and Development at Sonova
Manuel graduated with a bachelor in Systems Engineering and master in Biomedical Engineering. For the past 8 years he has been working for Sonova in electro-acoustic research and development. When not developing any new acoustic features, he enjoys outdoor sports, like climbing, hiking, mountain bike and wind surfing.
As a Product Audiologist at Phonak, I am lucky to work closely with a lot of brilliant engineers who develop new hearing aid features that improve lives. Manuel Weibel is one of them. This week, I had the pleasure of interviewing him about the development process of ActiveVent.
Here is our interview…
Manuel, thanks for taking time. I first started working on the ActiveVent project a year ago, but I understand that you have been working on this for a lot longer.
Yes, the project started around 2016. The idea came from a well-known clinical challenge that hearing care professionals face every day – whether to choose an open dome for low occlusion to improve ‘own voice’ comfort or choose a more closed dome to boost the low frequencies and improve performance in noise. The goal of the project was to create a receiver that could do both.
I was still working in clinic when the first open fit SlimTube hearing aids were launched on the market. This in itself was a big step in being able to offer more open fittings especially for mild hearing losses or for those with good low frequency hearing. And then a few years later the innovation of RIC devices further extended the benefit of open fittings.
Yes, but even with RIC fittings we know that fittings could be optimized further.
What do you mean?
With open acoustic couplings, like an open dome, there is the chance of comb filter effects which can result in the perception of an echo. This limits the vent loss compensation and the gain in low frequencies. Also, small or medium receivers doesn’t have the power to fully compensate the vent los. This results in a loss of low frequency output and the end user experiences reduced sound quality during situations such as streaming.
I would estimate over 20,000 development hours have been invested into ActiveVent.”
But that’s not all. I have seen so many discussions in online audiology forums about the effectiveness of directional beamforming technology with an open fit. However the alternative of a more closed coupling has the risk of occlusion – which can really reduce hearing aid acceptance.
For many fittings, hearing care professionals really need to find that balance between own voice comfort and hearing performance.
Exactly, that is why we spent so many years fine-tuning the design of ActiveVent. The project started around 2016. From idea through to final product I would estimate that over 20,000 development hours have been invested into ActiveVent.
That’s amazing – a lot of people from various departments all working together on this small receiver. And you have been working on the project from the beginning?
Yes, almost right from beginning.
What was the most challenging part of the project?
The biggest challenge was the extremely limited space available in the receiver chamber. In a tube of 12mm length and 4mm diameter, we needed to integrate a wide-band balanced armature receiver, an electromagnetic valve and protection against earwax and other potentially damaging substances.
With rigid support and connections, it was a challenge to fit all that in such a small tube.
Wow that really is micro-mechanical engineering!
Absolutely! So physical constraints is one aspect, then we had to balance three key elements: acoustic performance, reliability and fit-rate. We learned that if we tried to push too much on one element than one of the other two elements would be compromised. So, it was a delicate balancing act.
In regards to reliability, what did you find out?
We performed various highly accelerated life tests (HALT) to improve and verify the design. For example, we exposed the receiver to artificial ear-wax and sweat. We also tested if the mechanics could endure a large number of switching cycles (repeatedly opening and closing the vent) and only stopped the test after 200’000 cycles without any failure.
To conclude the lab tests, we performed a large reliability study in US and China that included real-life testing on hearing aid wearers. After all of those verifications, we are convinced, that ActiveVent is a robust product.
I can imagine with such a small moving part it can be quite susceptible to things like dust and wax.
Yes, we learned that the presence of wax is a critical factor in the lifespan of ActiveVent. Even a small amount can interfere with the mechanical vent function.
So we need to train our hearing care professionals to keep factors such as ‘waxy ears’ in mind when determining candidacy of ActiveVent. It is great that myPhonak 4.0.4 app has a new cleaning reminder function that reminds the user when to clean and change the wax guard of their hearing aids. This function will be particularly useful for ActiveVent users.
Manuel we have just talked about the technical aspects of ActiveVent. How do you think this translates into real-life end user benefits?
From my own personal experience, I have been wearing hearing aids with ActiveVent for the last four years. Two years ago, we introduced a firmware on the hearing aid which allows a comfortable use of these receivers. Since then, I have been wearing them almost daily.
What I like the best is the streaming sound quality. When I’m traveling by train, I mute the mics and do not get the distracting environmental sounds coming through because the vent is closed. When I want to communicate or listen to the environment, I double-tap and am back in the real world.
I agree, I use mine to listen to music when I go running. Actually, I tried them out the other night at a noisy restaurant with friends. I set up two manual programs so I could manually switch between open and closed vent.
I could really hear the difference in background noise suppression when I toggled between the two programs.
Don’t we already have some results from the study conducted at the National Acoustic Labs in Sydney?
Yes, that is right. The lab testing showed that with ActiveVent the study participants experienced an average of 10% improvement in speech intelligibility in noise compared to conventional acoustic coupling while providing natural sound in different listening situations.1
And not only that, the study also showed that ActiveVent preserves naturalness of own voice perception while improving hearing performance.1
We have so much anecdotal evidence from internal testers, like ourselves. But it is gratifying, after so many years of working on this product, to see such results coming from a clinical study conducted at a respected research center.
A big Kudos to you and team! I can’t wait to get in touch with my former colleagues who are still working in clinic to hear their experiences with ActiveVent. I know this will help solve that dilemma of how to balance comfort and hearing performance.
To learn more about the evidence-based research at the core of our products and features, we invite you to visit the Phonak Evidence page. And to learn more about ActiveVent Receiver and watch a video on how it works, we invite you to the Phonak product page.
- Latzel, M & Hobi, S. (2021) Receiver with mechanical vent provides benefit of open and closed acoustics for better speech understanding in noise and naturalness of own voice perception. Phonak Field Study News in preparation. Expected end of 2021.
Theory to Practice is a series of interviews with experts in the field of audiology and beyond. Interviewees share their knowledge and insights on relevant topics. The special focus of each interview is to translate theory into key take-aways which can be implemented into daily practice.