Wind noise in hearing aids with directional and omnidirectionalmicrophones: Polar characteristics of custom-made hearingBids

摘要

The purpose of this study was to examine the characteristics of wind noise at the output ofin-the-ear, in-the-canal, and completely-in-the-canal hearing aids. The hearing aids were programedto have linear amplification with matching flat frequency responses for directional (DIR) andomnidirectional (OMNI) microphones. The microphone output was then recorded in a quiet windtunnel when the Knowles electronic manikin for acoustic research (KEMAR) head was turned from0° to 360°. The overall, 125, 500, and 2000 Hz one-third octave band flow noise levels werecalculated and plotted in polar patterns. Correlation coefficients, average differences, and leveldifferences between DIR and OMNI were also calculated. Flow noise levels were the highest whenKEMAR was facing the direction of the flow and angles between 190° and 250°. The noise levelswere the lowest when the hearing aids were facing the direction of the flow. The polar patterns ofDIR and OMNI had similar shapes and DIR generally had higher levels than OMNI. DIR, however,could have lower levels than OMNI in some angles because of its capability to reduce noise in thefar field. Comparisons of polar characteristics with behind-the-ear hearing aids, and clinical andengineering design applications of current results are discussed.