Hearing aids are vital to millions of Americans with hearing loss. But as well as they perform, they do not work for all types of hearing loss. For some individuals, implantable hearing devices might be the key to improved communication.
Two types of implantable hearing devices are cochlear implants and bone anchored hearing aids.
Types of Implantable Hearing Devices
Cochlear implants are devices that are implanted surgically behind the ear. Cochlear implants are devices that contain an external portion consisting of a microphone, sound processor and transmitter, and an internal portion that includes a receiver, and electrodes that are placed inside the cochlea.
How Does a Cochlear Implant Work?
Cochlear implants provide for understanding of speech and other sounds. Cochlear implants can provide more access to sound compared to hearing aids and allow for understanding of speech and other sounds. The cochlear implant microphone picks up sounds in the environment, which are then converted by the sound processor into electronic signals that are sent to the transmitter. The transmitter forwards these signals to the receiver, where they are then passed to electrodes inside the cochlea. The electrodes stimulate the auditory nerve, which carries the information directly to the brain, where it is interpreted as sound.
Traditionally, cochlear implants have been primarily used for patients with profound sensorineural hearing loss, who do not benefit from hearing aids. However, as cochlear implant technology has improved, they are now also used in patients with single sided sensorineural hearing loss, and even in patients who have residual low frequency hearing, that do not adequately benefit from hearing aids.
Bone Anchored Hearing Devices
Bone anchored hearing devices consist of an implant placed into the skull, and a sound processor that connects either to an abutment that protrudes through the skin, or to a magnet that is placed under the skin. This system bypasses the middle ear, transmitting sound directly to the bone of the inner ear.
How Does a Bone Anchored Hearing Device Work?
The bones of the skull act as conductors, transmitting these sound vibrations to the inner ear, where the nerve fibers responsible for hearing are stimulated. A bone anchored hearing device is especially useful for patients with conductive hearing loss and single-sided deafness.
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