Investigation of characteristics and generating mechanism of wind noise on external microphone of mobile device

Abstract

The multipurpose external microphone of mobile devices is exposed to the outside windy environment, which inevitably generates wind noise. The wind noise acts as noise in signal processing, like Active Noise Control and capturing voice, and damages the user's experience. This paper investigates the acoustic characteristics and generation mechanism of wind noise through experiments and numerical analysis for a commercial TWS earbuds model. The experimental results show that the wind noise has broadband characteristics with dominant low-frequency band noise (below 2500Hz), unlike general cavity flow. On the same model, the Lattice-Boltzmann method numerical analysis has been performed through powerFLOW software. The numerical result shows good agreement of +-3dB with experimental results in the 1/3 octave band spectrum for the wind noise band. Numerical results flow field investigation reveals that the disturbed flow field is induced by an interaction between the vortical structure of the inflow and separated flow field, which is governed by geometry configurations. The disturbances induce the complex pressure gradient on inflow into the microphone, measured as wind noise on the microphone. These results show that the wind noise measured by the microphone of mobile devices is a flow phenomenon caused by external excitation.