Knochenleitungshörgeräte: Brille, Stirnband oder Implantat? Ein Überblick über Bauformen, Einsatzgebiete und Funktionsweisen

If the fitting of a conventional hearing aid, which is worn behind or in the ear, cannot be resorted to, access to hearing can be opened up via a bone conduction hearing aid. For whom bone conduction devices are suitable, how sound transmission works without the involvement of the inner ear, which designs are available and how hearing can also be made possible for children without an implant, you will learn in this article.

Bone conduction hearing aids: areas of application

On the one hand, bone conduction hearing aids are used when, for anatomical reasons, the attachment of a hearing aid behind or in the ear is not feasible due to deformity or absence of the pinna. On the other hand, a conductive hearing loss, for example due to a deformation or absence of the ossicular chain or otosclerosis, as well as unilateral deafness are reasons for the alternative choice. In such hearing impairment, the outer or middle ear is affected, blocking the transmission of sound to the sensory cells of the inner ear. Consequently, a solution that stimulates the auditory nerve by other means, namely bone conduction, is needed.

Bone conduction hearing aids: how they work

Air conduction hearing aids pick up sound through their microphone, process it, and then emit it through the air in the ear canal using a receiver. Bone conduction hearing aids, on the other hand, use the natural ability of human bones to conduct sound to implement sound transmission through vibration. This requires close contact or pressing of the device onto the mastoid - the bead-like bone behind the ear - because it enables the transmission of vibrations to the inner ear.

More precisely, the process looks like this: The sound is picked up by the microphone, converted into electrical signals and passed on to the audio processor. The latter processes the signals depending on its settings. The result is now transmitted, instead of to a listener, to a transducer that performs another transformation. The product: vibrations.

The vibrations, in turn, are transmitted to the bone, which carries the sound to the inner ear. Thus, the middle ear is bypassed, justifying the suitability of bone conduction hearing aids for conductive hearing loss and the naming of the devices. Finally, in the inner ear, there is a transmission of the signals to the brain, which ultimately, after decoding the signals, is where hearing takes place.

Bone conduction hearing aid: designs

As with all types of hearing aids, bone conduction hearing aids come in different designs, each with advantages and disadvantages. Which variant is suitable for you personally can only be evaluated on the basis of individual sensations and needs, but here is an overview of the available wearing styles

Bone conduction hearing aid: glasses

Bone conduction hearing aid glasses are a relatively user-friendly form of bone conduction hearing aid. In most cases, the attachment of the hearing aid to the eyeglass temples takes place via click systems. Accordingly, wearing can be started quickly and easily - after only slight modification of the glasses. Alternatively, hearing glasses are available in which the hearing aid is firmly anchored in the glasses. To use them, the glasses simply need to be put on. The most important factor here is the pressure required for the temples of the glasses to rest against the skull to ensure sound transmission. This is a subtle form of hearing support that is uncomplicated to put on and take off, but there is a disadvantage in that this variant is only useful in cases of simultaneous visual impairment. Consequently, fixed hearing glasses are less suitable for people who rely on visual aids only in certain situations.

Bone conduction hearing aid: headset

Bone conduction hearing aids are also available in headset form. In this design, the hearing system is built into the temples of the headset, which means that it automatically rests on the head. Just as with hearing glasses, the motto here is: Put it on and listen! Thanks to its adjustability, the hearing aid can be individually adapted to the head. The possibility of rapid mounting and dismounting additionally increases the user-friendliness. One disadvantage, however, is evident in the fact that over-ear headphones are generally difficult to wear over the headset.

Bone conduction hearing aid: for sticking

The bone conduction hearing aid for gluing on is attached directly to the skin behind the ear, which, compared to the above-mentioned designs, exerts significantly less pressure on the skull. The audio processor, which enables vibration-based hearing, is attached to the adhesive adapter. This design of bone conduction hearing aid is particularly suitable for children or babies because it does not require surgery, requires little supervision while worn, and is easy to test out. In addition, there is much less risk of deforming the skull bone as the child grows.

Bone conduction hearing aid: headband

Headbands are also specifically suited for children, as they are considered gentle, do not get in the way of children's play, and have thus proven to be a practical everyday companion. However, it should be noted that the pressure of pressing can lead to pressure sores as well as headaches and the headband may therefore only be worn for a limited period or its position should be changed regularly.

Bone conduction hearing aid: Implant (BAHA)

Probably the most elaborate choice among bone conduction hearing aids is the "partially implanted" hearing aid, also called BAHA (= Bone Anchored Hearing AidDuring the required procedure, a titanium screw is implanted directly into the skull bone, to which the sound processor will be attached in the future. Sound waves are picked up by the processor and converted into vibrations that are transmitted to the titanium screw. With the help of bone conduction, the vibrations are transmitted via the screw to the inner ear.

The implant is particularly suitable for very severe conductive hearing loss because there is no attenuation of the transmission caused by skin. The result: better hearing quality at increased volume levels, as well as energy savings.

Bone conduction hearing aids: cost and subsidy

Bone conduction hearing aids that are not implanted fall under the standard subsidy regulations for hearing aids for those with statutory insurance. There are thus fixed lump sums for the assumption of costs, which can be inquired individually with the respective health insurance company. In the case of an implantation, on the other hand, the insurance provider covers all costs of the operation and implant. The prerequisite for this is prior approval.