Implanted hearing aid uses bone conduction to bypass defective middle ear


January 14, 2013

The external sound processor (top) and the actual implant, that make up the Bone Conduction Implant

The external sound processor (top) and the actual implant, that make up the Bone Conduction Implant

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There may soon be help for people who have been rendered functionally deaf by problems of the middle ear. Researchers from Sweden’s Chalmers University of Technology have developed an implant that bypasses the defective middle ear, transmitting sounds to the inner ear by sending vibrations right through the skull bone.

Developed by a team led by Prof. Bo Håkansson, the two-part Bone Conduction Implant (BCI) is intended mainly for use on “individuals who have been affected by chronic inflammation of the outer or middle ear, or bone disease, or who have congenital malformations of the outer ear, auditory canal or middle ear.” Regular hearing aids typically don’t work for such people, as they’re usually designed for dealing with problems of the inner ear.

The implant itself is a little less than six centimeters (2.4 inches) long, and is attached behind the ear, under the skin, directly into the surface of the skull.

It’s paired with an external sound processor, which is what actually receives sounds from the outside world. This unit is placed against the skin, directly adjacent to the implant, and is held in place by magnets in both devices. An inductive coil in the implant allows it to receive sound transmitted through the skin, from the processor. The implant then uses a miniature quadratic loudspeaker to relay those sound vibrations into the bone of the skull, through which they travel to the inner ear.

Sounds are picked up by the processor (top), transmitted through the skin to the implant, and then transmitted by the implant into the skull bone

Previous bone conduction-based hearing aids have required the patient to have a titanium screw permanently protruding from the skull through the skin, to which the external device itself is attached. Such a set-up can result in infections, and the possibility of the screw falling out. With the BCI, the skin is left intact (once it’s healed up, after the insertion of the implant), and the processor can simply be pulled off when not needed.

A deaf test subject received a BCI last month, although Håkansson and his team are still waiting for the incision to heal before turning the accompanying processor on. Sahlgrenska University Hospital's Måns Eeg-Olofsson, who has been in charge of the medical aspects of the research, performed the procedure.

If it works as hoped, clinical trials will follow, with possible widespread use of the BCI within one to two years.

Source: Chalmers University of Technology

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

I'm assuming the battery in the implant is charged inductively? If there is no battery - how powerful could the passive inductive device be?

Daniel Brown

The battery is only in the external unit. The signal is transmitted using amplitude modulation via an inductive link and the maximum output level is on the same level as conventional bone anchored hearing aids stimulating the bone via a percutaneous implant. The proximity to the cochlea is a great advantage with the BCI.

Bo Håkansson

Both my children have a congenital hearing problem that is, thankfully, able to be mitigated with hearing aids. They both have slightly deformed bones in the middle ear that don't let efficient transmission of sound to the inner ear. Although they both have adapted to hearing aids, would this device be beneficial to them over the long run?

Davis Clay

It seems that your children has a conductive hearing loss and that is actually what this device is aimed for. To know more exactly one need to evaluate the audiogram that must include both air and bone conduction hearing thresholds.

Bo Håkansson

I had several surgeries because of an infection to the mastoid bone behind the ear, the communication bones where remove and my hearing is only 10 to 20 percent. Is it possible to enlist on the trials and if so, who would I need to get in touch to schedule see that this is possible. Would you please let me know. Thanks


I have read this article with a great interest. I very much interested to find out how the ear implant patient is doing. I am deaf in my right ear and started to lose hearing in my left ear. Any updates please. Munir USA

Munir Chavla
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