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Abstract
Abstract
Objective: The objectives of this study were: (1) to examine the effect of wide dynamic range compression (WDRC) and modulation-based noise reduction (NR) algorithms on wind noise levels at the hearing aid output; and (2) to derive effective strategies for clinicians and engineers to reduce wind noise in hearing aids. Design: Three digital hearing aids were fitted to KEMAR. The noise output was recorded at flow velocities of 0, 4.5, 9.0, and 13.5 m/s in a wind tunnel as the KEMAR head was turned from 0° to 360°. Study sample: Flow noise levels were compared between the 1:1 linear and 3:1 WDRC conditions, and between NR-activated and NR-deactivated conditions when the hearing aid was programmed to the directional and omnidirectional modes. Results: The results showed that: (1) WDRC increased low-level noise and reduced high-level noise; and (2) different noise reduction algorithms provided different amounts of wind noise reduction in different microphone modes, frequency regions, flow velocities, and head angles. Conclusions: Wind noise can be reduced by decreasing the gain for low-level inputs, increasing the compression ratio for high-level inputs, and activating modulation-based noise reduction algorithms.
Acknowledgements
The results of this study were presented in AudiologyNow! 2009, April 2009, in Dallas, Texas, USA. The title of the presentation was ‘Effects of Signal Processing Algorithms on Wind Noise in Hearing Aids.’ The author would like to thank the Herrick Laboratories staff and Nicholas McKibben for technical support, and Sonic Innovations for donating one of the hearing aids.
Declaration of interest: There are no conflicts of interest.