Compression Fitting of Hearing Aids and Implementation

A compressor in hearing aid devices (HADs) is responsible for mapping the dynamic range of input signals to the residual dynamic range of hearing-impaired (HI) patients. Gains and parameters of the compressor are set according to the HI patient's preferences. In different surroundings depending upon noise level, the patient may seek to tune the parameters to improve performance. Traditionally, fitting of the hearing aids is done by an audiologist using hearing aid software and the HI patient's opinion at a clinic. In this paper, we propose a frequency-based multi-band compressor implemented as a smartphone application, which can be used as an alternative to that of the traditional HADs. The proposed solution allows the user to tune the compression parameters for each band along with a choice of compression speed and fitting strategy. Exploiting smartphone processing and hardware capabilities, the application can be used for bilateral hearing loss. The performance of this easy-to-use smartphone-based application is compared with traditional HADs using a hearing aid test system. Objective and subjective evaluations are also carried out to quantify the performance.