Electronic Implant Replaces Impaired Middle Ear

Functionally deaf patients can gain normal hearing with a new bone anchored hearing aid (BAHA) implant that uses bone conduction to transmit sound vibrations to the inner ear.

Developed by researchers at Chalmers University of Technology (Gothenburg, Sweden) and Sahlgrenska University Hospital (Gothenburg, Sweden), the Bone Conduction Implant (BCI) BAHA has been designed to treat mechanical hearing loss in individuals who have been affected by chronic inflammation of the outer or middle ear, bone disease, or who have congenital malformations of the outer ear, auditory canal, or middle ear. The BCI does not need to be anchored to the skull bone using a titanium screw through the skin, as do current bone-conduction devices.


The device comprises two parts: one exterior processor and one implant, slightly less than six cm long, which is inserted just behind the ear, under the skin, into the bone itself. A coil placed at the upper end uses magnetic induction to couple with the outer, visible component, an external sound processor held in place with two magnets that the patient can easily remove and attach from the head. The inductive link transmits sound from the patient's surroundings through to an internal receiver, with the audio signal transmitted to a tiny quadratic loudspeaker anchored to the bone near the auditory canal. The speaker generates sound vibrations, which reach the sensory organs of the cochlea.

“The implant will be very comfortable and aesthetically attractive. Because the implant is securely fixed under the skin, the patient won't need to be more careful than other people during, for example, outdoor activities, and water sports,” said Prof. Bo Håkansson, PhD, of the department of signals and systems at Chalmers.” You hear 50% of your own voice through bone conduction, so you perceive this sound as quite natural.”

“Earlier tests indicate that the volume may be around 5 decibels higher and the quality of sound at high frequencies will be better with BCI than with previous bone-anchored techniques,” added Måns Eeg-Olofsson, MD, who implanted the first device in December 2012. “Now it's time to activate the first patient's implant, and adapt it to the patient's hearing and wishes. Then hearing tests and checks will be performed roughly every three months until a year after the operation. At that point, we will end the process with a final X-ray examination and final hearing tests. If we get good early indications we will continue operating other patients during this spring already.”

Related Links:
Chalmers University of Technology
Sahlgrenska University Hospital