3 Hearing aids employ DRC to optimally utilize the residual dynamic range of HI person. This reduced dynamic range of audibility is known as residual dynamic range. 2 A hearing-impaired (HI) person encounters difficulty in understanding or listening to sounds that are below their hearing threshold level. At present hearing aids are the most common solution to sensorineural hearing loss. 1 In this paper, we will focus on the importance of DRC in hearing aid application. DRC is commonly used in music production, sound systems, hearing aids, amplifiers, and broadcasting etc.

This signal processing operation can be considered as loudness equalization which adjusts the amplitude ratio between highest to lowest intensities in every frequency band of a signal. The objective and subjective test results demonstrate the performance of proposed method compared to fixed compression approaches.ĭynamic Range Compressor (DRC) is a variable gain amplifier where loud sounds higher than the predefined threshold level are compressed and softer sounds are provided with adequate gain in different frequency bands. The proposed frequency-based adaptive MBDR compression method is implemented on smartphone. Gain, threshold and compression ratio of the compressor for nine bands are adjusted based on the audiogram of the hearing impaired patient. In this study, we propose a frequency(FFT) based nine-band adaptive MBDR compression which uses spectral flux as a measure of the intensity change in input level to adapt the speed of the compressor in each band. Therefore, a fixed speed in compression might affect the performance of the hearing aids. HADs may operate in a variable acoustic environment. Alternatively, slow-acting compressor maintains the temporal cues and the listening comfort but may provide inadequate gain for soft inputs that come right after loud inputs. Traditional fast-acting compressor preserves the audible cues in quiet speech but, in presence of surrounding noise, it can degrade the sound quality by introducing pumping and breathing effects. Operating speed of the MBDR compressor plays an important role in preserving the quality and intelligibility of the output signal. Multi-band Dynamic Range (MBDR) Compression is a key part of the signal processing operation in hearing aid devices (HADs).

Multi band vs single band compressor