What Are Bone Conduction Hearing Aids?
Regular hearing aids take sound from outside the ear, amplify it in the middle ear, and pass the sound on to the inner ear. Bone conduction hearing aids work differently. Like a regular hearing aid, it takes the outside sound signal. But, the bone conducting hearing aid sends the signal to an oscillator, rather than an earmold. The oscillator vibrates against the skull, and the vibration is interpreted by the inner ear as sound.
Bone conduction hearing aids are not as effective as regular hearing aids, but they are intended for those who can't use one. They are good for hearing disorders like Atresia, which affects children. Atresia means that the hearing canal is blocked. A regular hearing aid is ineffective because no sound can pass from the outer to the inner ear.
You may need a bone conduction hearing aid if you have persistent ear infections or eczema. If the ear canal is smaller than normal, or if some portion of the ear canal is gone, a bone conduction hearing aid may be necessary.
Bone conduction hearing aids are suitable for children. They are also good for those who suffer from temporary hearing loss, due to blockage, infection or injury.
Hearing aids that operate through bone conduction are used by less than 1% of hearing aid wearers. This means they can be hard to find. Talk to your audiologist or medical specialist about where to buy one.
There are some problems with bone conduction hearing aids. Like a regular hearing aid, they cannot reproduce the sound exactly. The sound is similar to what you hear from a telephone.
Another disadvantage of bone conduction hearing aids is that the sound is mono, not stereo. When the sound vibration comes through bone, the listener can't tell where the sound is coming from.
A bone conduction hearing aid consists of a hearing device and a headband to keep the device in place. The headband must be tight so that the vibrations are strong within the skull, so they are sometimes uncomfortable.
When these hearing aids were first developed, they were fitted inside glasses. At the time, more glasses-wearers preferred thick lenses, so a tiny device could be implanted in the glasses, and its vibrations could be felt.
New models of bone conduction hearing aids use a device that is surgically implanted. One company that produces models such as this is BAHA (Bone Anchored Hearing Aids), based in Sweden. Because it works directly on the bone and does not need to pass through skin, there are a few advantages to implanting the device:
- The device doesn't need as much power to operate.
- The frequency range is wider, so that the sound quality is better.
- There is less distortion.
A BAHA hearing aid should be used only as a last result. You may want to use one if you have permanent hearing damage that can't be surgically improved. You should exhaust all other options before going for the implant.