cochlearr implant is performed for completely deaf individuals who cannot use hearing aids. These individuals are classified in two groups: i) congenital deaf who are born deaf and not learn to speak and the only way to help them is cochlear implant; ii) deaf individuals who can talk and have become deaf due to infections, accidents, or hereditary diseases. Individuals in this group gradually lose their speaking capability. The first group can have cochlear implant before the age of 5; although, the implant is performed until the age of 10 and in which case the result is not satisfactory as should. The reason is that after the age of 5, the patient hears the voices but cannot recognize them. Due to complicacy and costs of the operation, only the 100% deaf have the priority.
In Iran, the implants are imported and the operation is performed by Iranian experts. The problem is the price ofthe implants that makes the operation, without government subsidies, limited to few operation each year. Given the available capacity in the country to perform more implant operations, more patients can enjoy the services by cutting the cost of the implant.
A cochlear implant is comprised of:
Audio signal receiver and microphone: this element with a very sensitive microphone is placed behind the auricle.
Speech processor: processes received signals by the receiver and through extracting timing and frequency of the signal, the intensity of stimulation by the electrodes is determined based on the received voices.
Speech processor and external unit connection: the unit sends audio signals to the processor by wire and sends the output signal to RF transmitter behind the auricle. The output signal of the speech processor is sent in series with specific information structures.
Modulator – RF transmitter: The received information from speech processors is sent to the implanted unit via an RF link so that radio connection is established using proper coupling.
Receiver-stimulator: this part is implanted inside the head and receives RF signals, demodulates, and decodes them and generates stimulator pulses for each electrodes based on the received information.
Electrodes implemented in cochlear: the electrodes implanted in the cochlear function as stimulation pulse generator that stimulates hearing neural fibers and creates sense of hearing.