A<unk>  <unk>  is a type of<unk> <unk>  based on<unk>  conduction. It is primarily suited for people who have conductive<unk>  losses, unilateral<unk>  loss, single-sided deafness and people with mixed<unk>  losses who cannot otherwise wear 'in the ear' or 'behind the ear'<unk> <unk> s. They are more expensive than conventional<unk> <unk> s, and their placement involves invasive surgery which carries a risk of complications, although when complications do occur, they are usually minor. Two of the causes of<unk>  loss are lack of function in the inner ear (cochlea) and when the sound has problems in reaching the nerve cells of the inner ear. Examples of the first include age-related<unk>  loss and<unk>  loss due to noise exposure. A patient born without external ear canals is an example of the latter for which a conventional<unk> <unk>  with a mould in the ear canal opening would not be effective. Some with this condition have normal inner ear function, as the external ear canal and the inner ear are developed at different stages during pregnancy. With normal inner anatomy, sound conducted by the skull<unk>  improves<unk> . A vibrator with a steel spring over the head or in heavy frames of eyeglasses pressed towards the<unk>  behind the ear has been used to bring sound to the inner ear. This has, however, several disadvantages, such as discomfort and pain due to the pressure needed. The sound quality is also impaired as much of the sound energy is lost in the soft tissue over the skull<unk> , particularly for the higher sound frequencies important for speech understanding in noise.
Bone-anchored hearing aid
Middle ear implant
Craniofacial prosthesis
Cochlear implant
Tinnitus retraining therapy
Vibroacoustic therapy
Totally implantable cochlear implant
Audio therapy