Modulation-based digital noise reduction for application to hearing protectors to reduce noise and maintain intelligibility.
OBJECTIVE
The objective of this study was to test the effects of modulation-based digital noise reduction (MB-DNR) on noise levels, speech intelligibility, and listening preference in four real-world noises.


BACKGROUND
A significant challenge in hearing protection device (HPD) design is to reduce ambient noise levels while maintaining users' ability to understand speech. MB-DNR technology, currently employed in hearing aids, potentially could be used to achieve these objectives.


METHODS
Speech and noise calibrated to signal-to-noise ratios (SNRs) of 0, -5, and -10 dB in the sound field were recorded at the outputs of two digital hearing aids in the ears of a Knowles Electronic Manikin for Acoustic Research with and without MB-DNR activated (i.e., NR and noNR, respectively). Listeners' speech intelligibility scores and sound quality preferences were evaluated while they listened to the recordings presented via ER-3A insert earphones at 85 dB SPL.


RESULTS
MB-DNR reduced the overall noise level by approximately 4 to 7 dB. Listeners obtained significantly higher speech intelligibility scores in the NR condition at an SNR of -10 dB in two noises and similar scores in the noNR and NR conditions in all other cases. They preferred the NR condition in all cases.


CONCLUSIONS
MB-DNR reduced overall noise level, enhanced sound quality, and maintained or improved speech intelligibility in the four military noises tested.


CONCLUSIONS
MB-DNR algorithms potentially could be incorporated into HPDs to enhance performance and increase user acceptance.
Chung
King
K
Department of Allied Health and Communicative Disorders, Northern Illinois University, 323 Wirtz Hall, DeKalb, IL 60115, USA. kchung@niu.edu
Tufts
Jennifer
J
Nelson
Lance
L
D004430:Ear Protective Devices / Q000592:standards*; D006801:Humans; D009622:Noise / Q000517:prevention & control*; D012815:Signal Processing, Computer-Assisted; D013065:Speech Intelligibility