Objective: Systematic evaluation and meta-analysis of the effects of digital noise reduction (DNR) algorithms on speech intelligibility, sound quality and listening effort in adult populations. Design: Systematic review and meta-analysis. Study sample: Six databases were searched for experimental studies published from 2000 to 2017 in English using the following search terms: "hearing aid" and "noise reduction". A total of 264 unique hits were obtained; out of which, 16 studies were included. Results: The population effect was estimated for speech intelligibility and other subjective measures. From six studies, the population effect estimated for speech intelligibility measures was small (r = 0.28) with zero population variance. Sample size variance accounted for all the effect size variations found across studies. The population effect for subjective measures was medium (r = 0.46 ± 0.10) as calculated from seven studies. Conclusions: Based on a criterion of moderate evidence, this meta-analysis did not reveal a consistent improvement in speech intelligibility with DNR in adult population. The subjective outcome measures (e.g., acceptable noise level and sound quality judgment) showed a moderate positive effect of DNR. Implications for Rehabilitation The findings of the study will provide useful clinical information in follow up visits in audiologic rehabilitation. The meta-analysis of DNR informs clinicians to create realistic expectations in hearing aid users. This paper summarizes the available data on different outcome measures such as speech intelligibility, listening effort and sound quality. The results of this meta-analysis will help clinical audiologists in devising hearing aid orientation and counseling.
Objective: Systematic evaluation and meta-analysis of the effects of digital noise reduction (DNR) algorithms on speech intelligibility, sound quality and listening effort in adult populations. Design: Systematic review and meta-analysis. Study sample: Six databases were searched for experimental studies published from 2000 to 2017 in English using the following search terms: "hearing aid" and "noise reduction". A total of 264 unique hits were obtained; out of which, 16 studies were included. Results: The population effect was estimated for speech intelligibility and other subjective measures. From six studies, the population effect estimated for speech intelligibility measures was small (r = 0.28) with zero population variance. Sample size variance accounted for all the effect size variations found across studies. The population effect for subjective measures was medium (r = 0.46 ± 0.10) as calculated from seven studies. Conclusions: Based on a criterion of moderate evidence, this meta-analysis did not reveal a consistent improvement in speech intelligibility with DNR in adult population. The subjective outcome measures (e.g., acceptable noise level and sound quality judgment) showed a moderate positive effect of DNR. Implications for Rehabilitation The findings of the study will provide useful clinical information in follow up visits in audiologic rehabilitation. The meta-analysis of DNR informs clinicians to create realistic expectations in hearing aid users. This paper summarizes the available data on different outcome measures such as speech intelligibility, listening effort and sound quality. The results of this meta-analysis will help clinical audiologists in devising hearing aid orientation and counseling.