Cochlear Implant Programming through the Internet

Cochlear Implants

A cochlear implant is an electronic device that replaces the auditory system, mainly the sensory capillary cells in the organ of Corti in the cochlea (Kyriafinis, 2005). A modern cochlear implant is composed of two parts: one is the cochlear implant that is surgically implanted in the recipient and the second is the speech processor that is commonly worn behind the ear and communicates with the implant via an RF transmitter. In order to successfully stimulate the auditory nerve so that the recipient can perceive sound, sound waves must be transformed to electric pulses. This process begins at the speech processor where the sound wave is collected through a microphone. Afterwards sound waves are converted into an electric sound signal that is filtered, encoded and transformed through a very specific procedure. This signal is channeled through the speech processors transmitter to the implants receiver via an RF link. This signal contains the sound signal, the mapping of the T and C Levels, the amplitude and electrical pathway for each electrode passes the signal to the auditory nerve, as well as information regarding the decoding of the input signal. There is also communication from the implant to the speech processor that mainly includes the functioning state of each electrode and the impedance that is measured at each one. The speech processor apart from the data mentioned above also supplies the implant with the power required in order to function. The implant converts the incoming sound signal into electric signals that reach the cochlear nerve through an array of electrodes ranging from 12 to 22 depending on the implant model and brand. These electric signals stimulate the nerve in a way that simulates the normal function of the cochlea. From this point on the auditory signal follows the natural course to the primary auditory cortex on the cerebral cortex. This series to steps allows the recipient to perceive sound.

The process of converting the sound waves into an auditory signal is as mentioned above very specific an happens through specialized hardware and software in the sound processor as well as the implant. For every cochlear implant recipient the auditory nerve and brain respond differently to the electrical stimulus that is produced by the electrode array. As such one configuration cannot be applied to all recipients. Differences lie in the amplitude of the sound where a normal audio level for one patient can be perceived as painful for another. Sound amplitude is demonstrated in cochlear implants as the amplitude of the electric signal. Differences also lie in frequency. Frequency is demonstrated as channels that are respective to a single electrode in the electrode array. In the case of frequency differences the amplitude of each frequency must be adjusted for each recipient, and the correct channel levels must be selected.

Every channel has three main characteristics that are:

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  The Threshold or T Level, which is the lowest electrical level that causes an auditory response to the recipient

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  The Comfortable or C Level, which is the highest electrical level that causes a loud auditory response to the recipient while still being pleasant and

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  The Dynamic Range which is simply the difference between the T and C Level.

It is important to note that the specific value of the T and C Levels as well as the Dynamic Range value is not important. What is most important is that these values provide the auditory response that is ideal for each recipient. The procedure of setting the above levels to their values is called mapping or programming of the cochlear implant (Kyriafinis, 2005).

Remote Cochlear Implant Programming

In order to correctly program the cochlear implant it is usually required that the recipient visits a programming center. In these programming centers, programming of the cochlear implant is most commonly done by a doctor or audiologist but other suitably trained professionals can take part under the supervision of a doctor. The programming session is usually conducted by constantly receiving feedback from the cochlear implant recipient in order to correctly set the T and C Levels. It is also required that the doctor cooperates with other specialists especially in the cases of toddlers, children and other recipients that require special care. During the programming sessions specialized software and hardware are required that will enable the doctor to communicate with the implant and successfully achieve the desired result.