The Effect of Digital Noise Reduction (DNR) in Hearing Aids on Auditory Late Latency Response, Speech Recognition Ability and Quality

Abstract

The present study aimed to investigate the effect of Digital noise reduction (DNR) on auditory late latency response (ALLR), speech recognition ability (SRS) an quality of speech. The data were collected from 10 individuals with normal hearing and 14 individuals with hearing loss. The results revealed that there was a negative effect of noise on the SRS, latencies of ALLR components (Pl, NJ & P2) and the amplitude of Nl-P2 complex. The results also suggest that there was a slight improvement in SRS on activation of DNR. The improvement brought about by the DNR was not enough to bring the scores to that obtained under quiet condition. The DNR activation minimizes the effect of background noise by reducing the prolongation of the latencies of ALLR peaks. Nonetheless, the amplitude of Nl-P2 complex remained unchanged by the activation of DNR. Furthe1; there was no relationship between the SRS and Nl-P2 amplitude in quiet and noise. However, there was no correlation between the morphology ratings and SRS obtained under DNR activated and deactivated condition. In addition, DNR significantly improved the 'Loudness', 'Clarity', 'Naturalness' and 'Overall impression' ratings for the speech through the hearing aid. The quality ratings also appears to be 'acceptable to excellent reliability' between the two sessions on the three parameters namely 'loudness', 'Clarity' and 'Overall impression'. Overall, the effect of white noise was greater for individuals with hearing loss. Participants with moderate hearing loss are affected by noise to a greater degree compared to those with mild hearing loss.