What is a Bone Conduction Implant and How Does it Work?
Bone conduction implants are used for conductive - and mixed hearing losses, when sound cannot take its natural path through the outer and middle ear to the inner ear (e.g. due to malformations).
There are active and passive bone conduction systems.
How an active bone conduction implant works
Bone conduction hearing aids and bone anchored hearing aids (BAHAs) are examples of passive systems. Bone conduction implants are active systems. Bone conduction implants directly stimulate the bone. Passive bone conduction hearing aids apply vibrations to the bone indirectly through external pressure on the skin.
A bone conduction implant bypasses your outer and middle ear, transmitting sound waves through the bone straight to the cochlea in your inner ear.
The bone conduction implant consists of two components: the implant, which is surgically placed under the skin in the skull, and the external audio processor. It is held over the implant by a manget and can be discreetly worn under hair.
If you have a conductive hearing loss, Adhear might be an ideal hearing soution for you. This system uses the latest bone conduction technology, offering an excellent hearing experience without implantation. A thin adhesive adapter of the Adhear system sticks to the skin behind the ear without exerting pressure. This makes it ideal for babies and toddlers as well.
How an active bone conduction implant works:
- The audio processor collects sound waves through integrated microphones.
- The audio processor converts the sound waves to electrical signals.
- The electrical signals are transmitted through your skin to the implant.
- The implant converts the signals into mechanical vibrations, which are transmitted to your skull.
- Your skull bone conducts the vibrations to your inner ear.
- Your inner ear processes the mechanical vibrations in a natural way, transmitting the acoustic information to your brain.
Hearing thresholds must be 45 dB or better. Candidates for bone conduction implants cannot use conventional hearing aids for medical reasons.
A full hearing and medical assessment will be made to determine whether you are suitable for surgery and likely to derive sufficient benefit from the implant.
Who is an active bone conduction implant suitable for?
People with mild to moderate conductive hearing loss, including those who are deaf in just one ear (single-sided deafness) and who can't wear hearing aids for medical reasons such as discharging ears or the absence of ear canals. Because the skin heals after surgery and is therefore intact, it’s a good alternative for people who have problems with soft tissue healing, diabetes, skin or keloid scarring issues. You must be five years of age or older and have a functioning auditory nerve and cochlea. There is no upper age limit. You must have a functioning auditory nerve and cochlea.
Benefits of an active bone conduction implant system
- Volume and quality of sound are better than with passive systems as vibrations are generated inside your skull instead of having to pass through the skin.
- The audio processor, worn on the outside of your head, is much smaller, lighter and more discreet than the passive system’s sound processors.
- The active system is more comfortable because it doesn't require skin pressure for stimulation. It can be worn for a s long as you like, though you should be removed before sleeping or bathing.
- Compared with a bone-anchored hearing aid (BAHA), there is no titanium screw in the skin. With a BAHA, the pierced area requires daily cleaning and can cause skin irritations and infections in some people. There’s no risk of this with an active bone conduction implant because the skin is left intact.
Can you get an active bone conduction implant on the NHS?
There are no NICE guidelines for active bone conduction implants, although it is possible to get them through the NHS if you are found to be medically suitable.
What to look for in an active bone conduction implant system
- MRI safety – It’s important to know whether your device is compatible with MRI scanners used for diagnostic medical tests, and to what degree.
- Adaptive directional microphones – These help identify and filter out background noise.
- Feels and appearance – Audio processors vary in size, weight and some have interchangeable covers in different colours and designs, allowing you to make a bold statement or to wear it discreetly.
- Speech tracking – “ This helps identify the direction from which speech is coming, sharpening sound.
- Wireless connectivity – Your audio processor can connect to your mobile phone, mp3 player or assistive listening device.
- Remote control – You can quickly and easily make manual adjustments, if necessary, without removing the audio processor.
Things to consider
Hearing implant surgery is generally considered very safe but any type of surgery carries some degree of risk. This can range from risk due to anaesthetic and post-operative infection.
However, it’s a relatively quick and simple operation, taking from around 30 minutes to an hour, and can sometimes be done under a local anaesthetic. Ask your surgeon to explain how the risks and benefits apply to you.