The IUP Journal of Electrical and Electronics Engineering
Signal Processing Techniques Used in Digital Hearing-Aid Devices: A Review

Article Details
Pub. Date : Jan, 2020
Product Name : The IUP Journal of Electrical and Electronics Engineering
Product Type : Article
Product Code : IJEEE50120
Author Name : Manik S Sonawane, S R Chougule*
Availability : YES
Subject/Domain : Engineering
Download Format : PDF Format
No. of Pages : 11



Hearing impairment is a commonly observed human health problem across the world. In "hearing loss", hearing sensitivity is reduced. To treat hearing loss problem, hearing assistive devices are used. Hearing aids restore hearing ability for those having hearing problems. But with today's most advanced technologies in hearing aids, patients still have some difficulty in understanding speech in crowded areas. Hearing aid has hearing loss match up and adjustment of the hearing aid characteristics according to an individual patient. Digital hearing-aid device amplifies sound selectively by use of digital filters and the processed signal is transferred to the ear. Hearing-aid designers are continuously trying to minimize background sounds and noise with these additional directional microphones, adaptable noise reduction filters and uses of binaural hearing aid technologies to improve localization. Lots of studies have been already done to design digital filters for selective amplification. Most of the available hearing-aid designs have digital filter bank and fixed sub-band structure. Previous research aims at creating band decomposition, and the research is focused on using less complex algorithms for accomplishment of the decomposition of signals. The paper reviews available designs and reconfigurable digital filter banks to achieve the best fitting to audiogram.


According to World Health Organization, there are 278 million people have hearing loss problem. 13% people in developed countries suffer from hearing loss that affects their speech conversation skills and disable them from living a normal life. Around 90% of patients with hearing impairments require hearing aids.

But only 20% are interested in purchasing hearing aid, and about 25% having hearing aid do not use it because of irritating noise and unpleasant whistles with other amplified noises due to surrounding background noise in their everyday life (Alexandre et al., 2007). Many of the advanced technologies in signal processing are used in digital hearing aids available in market, but sadly, about 50% of patients are not satisfied with the performance of their hearing aids in crowed noisy situations. The reason for this dissatisfaction may be the algorithms used in filter designs do not decide which signal is required to be preserved and what to block as background noise. The hearing aid supports to restore audiogram gain (amplification) and dynamic range compression to make sounds of having low intensity audible and comfortable hearing of loud sounds. Although hearing aids are mostly successful in different listening situations, patients still have some difficulty in complex acoustic or crowded environments. Amplification of sound is the basic block for signal processing in digital hearing aid. But the challenge for hearing aid designers is to improve understanding of speech and restore loudness, and gain of the present hearing aids is kept nonlinear.


Hearing loss, Digital hearing aids, Digital filters, Reconfigurable filter

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