Insights from the Maker of the Smallest Implantable Hearing Device

The device is also first implantable hearing device to offer iPhone support.

Brian Buntz

The new Baha 5 hearing device from Cochlear Ltd. (Sydney, Australia) is unique in two ways: First, it is said to be the smallest bone conduction sound processor in the industry. And second, it is the first hearing implant to be compatible with iPhones, iPads, and iPad touch devices. The iOS device integration enables users to hear any sound emitted by the iDevices directly in their head. Users can also fine tune sound processing and adjust the volume from an app. "You can also geotag a restaurant, for instance, so the next time you go to the restaurant, the device automatically adjusts its sound profile," says Mats Dotevall, the company's director of design and development based in Mölnlycke, Sweden. The device also supports Apple's "Find My Device" functionality to help locate the sound processor when misplaced.

"You can also mute a certain sound type. So you can listen to music and mute external sounds," Dotevall says. "You can optimize it yourself; you don't have to go to the clinic and do fine tuning."

The device recently won the Red Dot Award: Product Design 2015.

The small footprint of the device is impressive when comparing it to that of earlier technologies. For instance, the old asymmetric transducer measured 7 × 13 × 14 mm while the new BCDrive transducer measures 6 × 9 × 14 mm. The volume of the device was reduced by 45% without losing output force. In addition, current consumption at equal output force level reduced by 36% and total harmonic distortion reduced by 30%.

In the following Q&A, Dotevall provides insights into the product's development and an overview of its functionality.
 

Qmed: Could you describe the capabilities of the Baha 5 Sound Processor and compare it to other products on the market?

Dotevall: I'll start by briefly describing how traditional hearing aids work for context. Those devices have a loudspeaker. Those devices amplify the sound that goes through the ear canal and then into the bones within the middle ear and finally into the inner ear, which is typically what is damaged for people who need this type of hearing aid. The damage can be as a result of age or noise-induced hearing loss.

Then you have the cochlear implant, which is a a very different type of product because it stimulates the nerves inside of the ear with an electronic signal. Babies that are born deaf can be treated with a cochlear implant and live a normal life.

The type of product we are working on is a bone-conduction device. It is for people that have some sort of issue with the outer ear, the ear canal, or the middle-ear bones. In some way, the sound doesn't really come to the inner ear for these patients. That could be genetic; it could be a result of a disease. Basically, your inner ear might be very healthy but sound doesn't reach it. So what we do is put an implant into the skull that integrates with the bone tissue. It vibrates and helps transmit sound to the inner ear. A sound processor picks up sound, amplifies it, and then vibrates the skull bone. The inner structure of the ear, the cochlea, and the hair-like stereocilia in the inner ear also vibrate. In that way, you can bypass the standard way of sound coming through the inner ear.

There is also another indication where the device is used: single-sided deafness. One side is completely deaf, which can be quite a big handicap in social environments, in the car, and so forth. For those patients, we put the device on the deaf side and then vibrate over to the hearing side.
 

Qmed: How did the company make this the smallest bone conduction sound processor on the market?

Dotevall: The key engine in all of this is the electromagnetic vibrator, which is small and it is driven by a small hearing device battery. We are using a different kind of architecture. The previous architecture had a simple design but it was asymmetrical. We made it symmetrical, which makes it more difficult to manufacture. Having this architecture makes the device much more efficient. With the same battery size, power output, and the same force from the vibrator, we could reduce the size substantially.

Qmed: What were the main factors that lead Cochlear to support Apple devices?

Dotevall: There have been some proprietary technologies for some time that could integrate hearing aids with smartphones using Bluetooth. What Apple did a couple of years ago is develop a new wireless technology that is similar to Bluetooth Smart, which is good for data transfer. But the Apple technology for hearing aids can actually stream sound directly from the iOS device to the hearing device. There is no other smartphone maker or platform that can do direct audio streaming to hearing devices. Apple licenses this technology out.

A patient can use this technology to hear whatever sound they want from a smartphone. They can hear that directly inside of the head. It is pretty cool.

We are the only company to offer this on the implantable hearing device front. There are only two traditional hearing aid manufacturers that offer Apple integration.

Qmed: What were the main challenges you encountered when engineering this technology?

Dotevall: These are tiny devices. You need to have a small DSP platform with radio circuitry and a very efficient antenna. One of the challenges is that these devices are very close to soft tissue and the frequency band is close to water and soft tissue. The closer are you to the back of the head and the skin, the more challenging it is for the antenna design for the 2.4 GHz band.

In addition to that, you have to integrate Apple's protocol into your normal signal processing architecture.

Brian Buntz is the editor-in-chief of MPMN and Qmed. Follow him on Twitter at @brian_buntz.

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