By Arthur Veen
The road to a BAHA - Don't worry, this is not a horror story about an ENT doctor who screwed up, but it does involve a screw. :-)
This is about a type of hearing aid that many people are unfamiliar with; because I may get one in the near future, I was asked to write something about it.
The type of sound transmission used by most hearing aids is called "air conduction". Another type of sound transmission is "bone conduction".
In bone conduction, vibrations travel through the bone of your head to the cochlea, where they are transformed back into sound. Very much like as if it would travel from your eardrum through the hearing bones in your middle ear. Some methods of bone conduction can be so uncomfortable, many people refuse to wear the aids.
The main advantage over common BTEs though is if you cannot use earmolds, in the canal hearing aids, earplugs, or air conduction for whatever reason, and a CI is also not an option for you, then bone conduction might be an alternative.
A BAHA is a particular hearing aid for bone conduction, which has been around since 1977. BAHA stands for Bone Anchored Hearing Aid, and as the name says, it is anchored to a bone. This also indicates that it uses bone conduction for transmission of sound.
Some examples of possible BAHA candidates:
The following may give you a clue. In Holland, the BAHA is sometimes referred to as "hearing screw".
A small titanium fixture ("screw") of 3-4 millimeters (1/8th - 1/6th of an inch) is placed into the bone behind your ear. After some 12 weeks, when the bone has healed, the screw should have integrated with the bone. This is the same principle that is used for plates to fixate the bone of a broken leg, for example.
An abutment is placed onto the screw/fixture; this is used to connect the hearing aid with the screw/fixture.
The two steps above are sometimes performed in a single surgery. This surgery is relatively minor, some 45 minutes under local anesthesia.
After surgery, a pressure bandage will be applied to make sure the skin will heal and enclose the fixture. After the abutment has been placed, you'll have to see your ENT doctor for checkup and cleaning of the skin around the abutment to prevent infections during the healing of the small wound. Approximately a month after the placement of the abutment, the hearing aid will be attached to the abutment for the first time.
The hearing aid will transform sounds into vibrations, which will be transmitted through the fixture to the bone, and then through the bone to the cochlea. Because a screw is used, there is no need for pressure on the bone, and it is experienced as much more comfortable than the "classic" bone conduction hearing aids.
Because the abutment is going through your skin, you need to clean the skin around the abutment every day, to prevent possible infections. You will have to see your ENT every six months to check out the fixture and abutment, and make sure everything is ok.
The BAHA does not work for everyone.
You need to have a reasonable bone conduction and your cochlea must be in a reasonable condition. If neither is the case, then a BAHA will not be of much help.
If your hearing nerve is damaged, it will probably not work well either.
When your hearing loss is above a certain level, the BAHA may not provide enough amplification.
A BAHA will not destroy any remaining hearing that is left, and the fixture can be removed when it no longer is helping.
Yes, a few of them are:
The manufacturer claims it is (almost) equal to that of most BTEs.
Some people who are used to air conduction say that the sound and volume are a bit different, and that it takes some time getting used to. It varies for each person. Compared to other bone conduction hearing aids, the BAHA is usually experienced as being an improvement.
Because the microphone does not pick up amplified sound as it would with air conduction hearing aids, there is considerably less chance for feedback.
Check out the manufacturer's website at http://www.cochlear.com and click on the links about BAHA.
Your ENT or local audiology center may be able to provide you with more information too. There are local offices of the manufacturer in several countries, where you can also obtain more information.
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