Comparison of Functional Gain and Insertion Gain in Linear and Non- linear Hearing Aids

Abstract

Hearing aid selection and fitting is a step-wise procedure involving hearing evaluation, pre- selection of hearing aid, hearing aid fitting, verification of hearing aid, and validation. As verification is one of the important steps, there is a need to evaluate the subjective and objective verification measures for the linear and non-linear hearing aids. This is because these hearing aids differ in terms of the amount of gain they provide at different input levels. To evaluate the effectiveness of the verification measures, 20 children with hearing impairment using hearing aids participated in the study. These children were in two age groups, Group I with 4+ to 5 years, and Group II with 5+ to 6 years. The results indicated no difference for insertion gain measures between the two age groups. The results also revealed that either the IG or FG can be used as verification measures, for linear hearing aids. This is because both of them provide comparable results for linear hearing aids. However, the values of FG and IG were different for non-linear hearing aids. The IG measures carried out at different levels reflected the non-linear functioning of a hearing aid.