How does a Cochlear Implant work?
The cochlear implant takes advantage of the things an ear can still do after hair cells have been damaged or destroyed. It also takes advantage of how smart and flexible the human brain can be. The cochlear implant creates a new way of hearing. Here’s how the implant works: A tiny microphone that is easy to wear captures the sounds of the doorbell, the car alarm, or a crying baby. The microphone collects and gives the vibrations of sound to a speech processor. The speech processor is a very complex electronic instrument that makes it possible to take the vibrations of speech and provide them to the auditory nerve as electronic signals. The implant is designed so that the nerve can use these electronic signals. The reason the cochlear implant is called an implant is that a surgeon puts it under the skin behind the ear and into the skull. During surgery, the surgeon threads the implant into the cochlea (the special organ of hearing that looks like a snail’s shell), past the damaged hair
A cochlear implant is very different from a hearing aid. Hearing aids amplify sounds so they may be detected by damaged ears. Cochlear implants bypass damaged portions of the ear and directly stimulate the auditory nerve. Signals generated by the implant are sent by way of the auditory nerve to the brain, which recognizes the signals as sound. Hearing through a cochlear implant is different from normal hearing and takes time to learn or relearn. However, it allows many people to recognize warning signals, understand other sounds in the environment, and enjoy a conversation in person or by telephone.
The cochlear implant bypasses the damaged parts of the inner ear and directly stimulates the remaining hearing nerve fibers in the cochlea with electrical signals. The cochlear implant consists of two basic components: an outer (external) and an inner (internal) device. The external device consists of a speech processor (see #2, figure below) (worn either as a body worn or as a behind-the-ear device(#2)), a transmitting coil(#4), a directional microphone(#1) and connecting cords(#3). The internal device consists of a receiver/stimular(#5) (placed directly below the skin) and a multi-electrode wire array(#6), which is inserted into the inner ear (cochlea). The transmitting coil of the external device is secured over the receiver/stimulator of the internal device through magnetic attraction. The Cochlear Implant System works in the following manner: • Sounds are picked up in the small, directional microphone located in the ear level speech processor. • The speech processor filters, analy
A cochlear implant receives sound from the outside environment, processes it, and sends small electric currents near the auditory nerve. These electric currents activate the nerve, which then sends a signal to the brain. The brain learns to recognize this signal and the person experiences this as “hearing”. The cochlear implant somewhat simulates natural hearing, where sound creates an electric current that stimulates the auditory nerve. However, the result is not the same as normal hearing.
1. The receiver/stimulator (implant) which is surgically implanted. 2. The speech processor (headpiece) which is not implanted and is worn externally either behind the ear (ear-level speech processor) or on the belt (body-worn processor) • Sound is picked up by the microphone which a component of the externally worn speech processor • The sound is converted in the speech processor to an electrical signal. The signal is then “coded” or converted to specific patterns or pulses. • This coded signal is then sent to the transmitting coil of the speech processor where it is sent to the receiving coil of the internal receiver/stimulator (the implant). The signal is sent across the skin inductively, there is no direct connection with the implant: the implant in totally implanted beneath the skin. • The implant now sends the coded electrical signal to the electrode array which is implanted into the cochlea. • Multiple channels and points of stimulation now fire in a pattern that the cochlea can
