Bone-conduction hearing devices transmit sound signals to the inner ear in the form of vibratory wave energy. These devices are categorized as either non-implantable or implantable, depending on whether surgical implantation is required. Non-implantable bone-conduction hearing aids include types such as soft-band, bone-conduction glasses, and dental bone-conduction devices. Their principle relies on applying a sound transducer to press against the skull, allowing sound vibrations to reach the inner ear. However, pressure at the contact point with the skin can lead to discomfort, while energy attenuation caused by the skin and subcutaneous tissue may reduce both comfort and effectiveness, limiting their use for certain patients.
Implantable bone-conduction hearing devices require surgical implantation to directly transmit sound vibrations to an implanted component driving the middle ear or the cortical bone of the mastoid, without affecting sound conduction through the eardrum or external auditory canal. Implantable bone-conduction hearing devices are further divided into bone-anchored hearing aids (BAHA) and devices like the Vibrant Soundbridge (VSB) or Bonebridge (BB), the latter two collectively referred to as middle ear implants (MEI). Clinically, these devices are applied in cases of conductive and mixed hearing loss, achieving effective hearing compensation through bone conduction.
Additionally, the open external auditory canal reduces the risk of ear canal infections and facilitates drainage in patients with chronic otitis media, while also minimizing the sensation of ear blockage.
To be continued