title: Wind noise in hearing aids: I. Effect of wide dynamic range compression and modulation-based noise reduction.
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.
  
  
  METHODS
  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°.
  
  
  METHODS
  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.
authors: Department of Allied Health and Communication Disorders, Northern Illinois University, DeKalb, Illinois 60115, USA. kchung@niu.edu
authors: King
authors: K
authors: Chung
mesh_terms: D000162:Acoustics; D000465:Algorithms; D001307:Auditory Perception; D004867:Equipment Design; D006310:Hearing Aids; D006801:Humans; D008348:Manikins; D008422:Materials Testing; D009038:Motion; D009622:Noise / Q000009:adverse effects / Q000517:prevention & control*; D010470:Perceptual Masking; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D014159:Transducers; D014919:Wind