A simple identification method of wind noise using the difference in wind speed generated inside of the wind screen (Outdoor verification experiment for infrasound)

Abstract

Focusing on the difference in wind speed due to different positions in a wind screen, we devised a simple method to recognize wind noise only by the difference in sound pressure level between two microphones placed in the wind screen. First, we conducted ventilation test with the wind screen, and confirmed that the wind speeds at the two different locations differed by 60 to 70%. Next, a loudspeaker test was conducted to examine the wind screen insertion loss and the effect of ground reflections on a microphone located 30 cm above from the ground. As a result, it was confirmed that the wind screen has almost no effect of 0.4 dB or more on the measurement of sounds below 50 Hz. Finally, a field experiment using a loudspeaker and natural wind was conducted to verify the discrimination performance of the devised method. We observed a sound with a certain sound power of 5 Hz using a loudspeaker, and tried to discriminate wind noise from the difference in sound pressure level between the two microphones placed in the wind screen. As a result, for example, when the discrimination threshold was set to a level difference of 2 dB, 89% of the data was discriminated correctly as wind noise, and 6% of the total number of data was recognized incorrectly. From those results, it was confirmed that wind noise can be easily and automatically discriminated by using the level difference from the results measured by the two microphones in the wind screen.