Cochlear implant models based on critical band filters

Cochlear implants (CI) are electrical prosthesis that partially replaces the function of the human ear. As cochlear implants are system specific there is a need for simulation of the system parameters prior to implantation. In the current work we have considered the system specific parameters like number of channels, type of filters by developing uniform bandwidth filter based acoustic CI model and an auditory model based CI system with frequency bands spacing similar to the critical bands of the auditory system. Acoustic CI simulations are generated for all the vowels and words from the list-1 of lexical neighborhood test using waveform and feature extraction strategies. The first four formant frequencies of each vowel are used as features. A closed set listening test is conducted and a comparative study is made among the systems developed. The perceptual quality of the speech is rated in a scale of 5 point grading. The acoustic CI simulations of all the words generated by critical band filter based CI system showed a grading of 4-5 as opposed to 2-4 for uniform filters based CI system.