What Are Bone-Anchored Hearing Aids (BAHA)?

Friday, August 24, 2012 | Unknown at 8:07 PM |

Bone-anchored hearing aids (BAHA) are surgically implanted hearing instruments. More of a prosthesis than a standard hearing aid, BAHAs are comprised of a titanium prosthesis surgically embedded into the skull with an abutment visible through the skin behind the ear connecting to a sound processor.

The sound processor picks up and transmits the sound to the prosthetic implant. The implant, in turn, stimulates the inner ear directly, improving hearing. The BAHA system is surgically anchored into the skull bones. Surgery is typically outpatient, but does require anesthesia. Risks are similar to that of other outpatient surgeries requiring anesthetics. A small incision is made behind the ear, and an approximately 3 mm deep hole is drilled into the skull bone.

The implant is inserted with the abutment just above the skin line, and the incision is closed. In 4-6 weeks, an appointment with an audiologist or ENT will be made and the BAHA's sound processor will be fit and programmed to suit the patient's hearing needs.

BAHAs are not for everyone. In order to fully comprehend how they work and who they are for, you must first understand how typical, normal hearing works. Normal hearing occurs through conduction of the sound by air and by bone. Air conduction describes that path to hearing that one might assume based on the anatomy of the ear. Sound waves are picked up as vibration of air molecules, and funneled by the outer ear into the ear canal.

The waves vibrate the ear drum and middle ear bones (commonly known as the hammer, anvil, and stirrup); information is sent to the inner ear, and transmitted to the brain to be processed. Bone conduction is the transmission of sound the inner ear and brain via the vibration of skull bones. It is because of bone conduction that people sound differently to themselves when heard via a recording. Low pitches are transmitted the most by bone conduction, so their own voice will tend to sound deeper to themselves than to others.

If the pathway used for air conduction is defective or damaged beyond repair, the bone conduction pathway may become an alternate source for sound information. Therefore, the BAHA is a great option for patients with chronic middle ear dysfunction or outer and middle ear deformities that cannot be otherwise corrected by surgery, other medical intervention, or traditional hearing aids.

BAHAs bypass the outer and middle ear pathways, by directly stimulating the inner ear by vibration of the skull bones, using the bone conduction pathway. These hearing instruments may also be useful for patients with little or no hearing on one side and normal hearing on the other. BAHAs serve to transmit the sound information from the poorer hearing side to the better, normal hearing ear.
Contact your audiologist or ENT about your candidacy for bone-anchored hearing aids!