ADAPTIVE EXPERT SYSTEM FOR CALCULATION OF REAL EAR INSERTION GAIN FOR DIGITAL HEARING AID

The various gain calculating formulae for digital hearing aids is analyzed for different subjects to find out suitable adaptive gain formula for most successful gain recommendations. The object of the work is to design and develop an adaptive expert system, which could be effectively used to perform screening tests to identify the level of hearing impairment and recommend suitable gain suggestions for frequency bands of digital hearing aid. Initially, the design requirements for a digital hearing aid are being arrived by using the standard gain formulae followed such as National Acoustic Laboratory Revised (NAL-R) and Prescription of Gain Output (POGO II). The test is carried with 272 subjects aging from 25 to 72 and 221 male and 51 female. Of which gain is recommended for 127 subjects with the standard gain formula. When the recommendations are verified for satisfaction among the hearing aid users only 28 received satisfaction with NAL-R and 25 received satisfactions with POGO II. Remaining subjects received satisfaction only after fine tuning the gain value and recommended gains are stored in adaptive expert system. Subsequently, based on the suggested value of gains and additional data from expert audiologists, gain formula could be made distinct for every language.