Breakthrough for GN’s developers: Compact hearing aid integrated into mini earbuds

Please build us a pair of earbuds. They should enhance the user’s hearing, be able to stream music, receive calls, have sophisticated noise reduction, and run on rechargeable batteries. Go ahead!

This was the design brief put in front of a team of GN developers.

The idea behind Jabra Enhance Plus, launched February 2022, has been to develop a hybrid earbud, helping people to hear better, while also being able to stream music and being used with a smartphone. The product is targeting people, that are not yet willing to wear a regular hearing aid.

Because, as research shows, there is a six-year gap between discovering that your hearing is slowly deteriorating, and you finally decide to visit an audiologist for the fitting of your first hearing aid.

For this customer segment, a casual hearing aid would be an acceptable solution: A pair of discreet wireless earbuds with design and features like Jabra products, enhanced with features and miniature technology from the hearing aid domain. Jabra Enhance Plus was to function as any other headset.

But at the same time, it would give the user the opportunity of switching on hearing enhancement if needed. Typically, this is required in large rooms packed with people, or in similar situations where numerous sound sources make life difficult for the hearing impaired.

 

Small and groundbreaking

The design brief gave the developers something to think about: They had to cram both headset and hearing aid functionality into one single product, with very little space available. A strong focus on miniaturization was needed. Developers were to work with a completely new form factor, as Jabra Enhance Plus is one of the world’s smallest hearing aids with built-in wireless functionality.

Furthermore, as the device had to be as discreet as possible, it was to be placed as far inside the ear as possible. That requirement posed a challenge regarding the robustness of the device. Also, the team?s antenna experts had their work cut out for them.

Jabra Enhance Plus will initially only be available in Japan and the US. In the US, customers can purchase them at selected audiologists, while GN is waiting for approval to sell them over the counter, for instance through electronics chains or web shops. Currently, hearing aids are only allowed to be sold via audiologists. In Japan local regulations already allow Japanese consumers to buy this kind of products through various channels, for instance two of the largest electronics chains (Bic and Yodobashi), Amazon, opticians, and audiologists.

 

Meet three people from the GN development team:

The back pocket problem: Bluetooth from smartphone to earbud

Soren Kvist, Senior Antenna Engineer, Radio Systems, GN Hearing

You can buy plenty of standard Bluetooth Low Energy antennas to put in a TV or a laptop. But when you work with antennas for hearing aids, the reduction in size means you have to customize a lot of things. The smaller the antenna, the worse the signal. That is why we have to utilize the space available as best we can. That means, that the shape of the circuit board and its position follows the two antennas inside the device. In fact, the electronics are actually a part of the antenna.

It’s the Bluetooth antenna and the magnetic induction antenna that decide the position of the other components. In this, every dB counts. In our first prototype, we had flipped the circuit board in a way we thought was optimal. But we were wrong. We turned it around and then everything was fine.

The physical design of the device gave us some challenges. When you place a sensitive Bluetooth antenna in the ear it influences transmission quality. In an early phase we ran some outdoor tests with the test person having his smartphone in is back pocket. When he turned his head in a certain angle, the signal disappeared. It worked well with the phone in the front pocket.

Indoor everything was fine as well. Finally, we had to revise our design. We asked, if we could increase the size of the housing, but got a no. Instead, we chose to optimize the radio system to enhance its performance sending and receiving Bluetooth signals.

That means we use a little more energy, but still the device runs up to 10 hours on a full charge.

 

Radio reach: 16 cm from ear to ear

Sinasi �zden, Senior RF Engineer, Radio Systems, GN Hearing

I’m responsible for the magnetic induction radio that connects the two earbuds. As opposed to the Bluetooth radio waves, which follow the contours of the body, the induction radio transmits directly. Typically, the distance between your ears is 16 cm. We have added a little extra so that it works, even if you have the largest head in the world.

The magnetic induction system is sensitive to electronics noise coming from other components in the device. Because of the tight space, noise gets close to the sensitive coil. The coil has nowhere to hide because it?s surrounded by noisy components, and so the signal to noise ration starts becoming an issue.

That is why you must be really careful when you’re doing stack-up. The various components have to be placed very carefully to work together. We work with simulation to find the correct position of the noise-sensitive components in relation to the noise-producing ones. The layout is essential. That goes for the 3D build, meaning where things are positioned, and it goes in regard to which print circuits are close to each other, and how they are placed in 3D, when we bend the circuit board.

All this you must decide on as quickly as possible. You have to frontload, as we call it, as early as possible. If you at a later stage in development are forced to change the position of some components, that means trouble. That is why we simulate and build prototypes. In this we can ensure that hardware is placed correctly and that the signal to noise ratio is acceptable.

That balance is hard to achieve, especially because we transmit with very little power, to be energy efficient. That means noise becomes a big issue. It takes a long time to find the right balance in such a small device.

 

The octopus: The ear is a messy place

Thorvaldur Oli Bodvarsson, Senior Electronics Engineer, GN Audio, Jabra (after finishing the project he has started in a new job internally at GN).

I’m the all-rounder looking at the infrastructure as a whole. My job is to ensure that all electronic components work together. I have a background in antennas, RF and acoustics. I’ve worked with all aspects of electronics, and I’m applying that knowledge to make the design work as a whole.

Electronics integration has been challenging, because of the size of the device. In addition to that, radio communication has been an issue as well.

My role is to talk to all the people involved in such a large-scale project. It requires a lot of meetings and discussions to make all requirements fit together. It’s not only about hardware and software, it’s about mechanics also. Not least, there is a strong focus on safety and robustness.

The ear is the worst possible place for electronics. There is sweat, ear wax and other substances that we need to keep out of the device. As Jabra Enhance Plus is an earbud, it’s particularly exposed, compared to conventional hearing aids placed behind the ear. We had to give the rechargeable battery an extra layer of protection. We chose to encapsulate it with a special coating applied under vacuum. We spent a lot of time to make it work, but we succeeded and now we’re very satisfied with the result.

Maybe the biggest challenge has been working with a completely new form factor. The team that designed the device had a very specific vision for it. Our task has been to make everything on the inside work. In this, it has been a great challenge to position the electronics correctly, and at the same time ensure reliability and robustness.