Outdoor measurement of sound absorption coefficient using combined particle velocity-pressure sensor - influence of wind screen

摘要

A combined particle velocity-pressure sensor (p-u sensor) is sometimes covered with a wind screen to prevent wind-induced noise when measurement of a sound absorption coefficient is conducted outdoors. Based on the measured results obtained using a p-u sensor covered with a 9-cm-diameter wind screen, we experimentally investigated the influences of a wind screen and of wind-induced noise on the measured results of absorption coefficients. The wind screen only slightly influenced the measured results for high-absorption material. However, for very small surface impedance of the material, it influenced the measured results. The wind-induced noise caused by air flow around the p-u sensor decreased the magnitude of acoustic impedance. This wind screen greatly reduced the wind-induced noise. However, the air flow of 5 m/s velocity slightly decreased the measured surface impedance, even when the p-u sensor was covered with the wind screen. It is therefore necessary to consider the power level of the sound source and the size and material of the wind screen in high-wind conditions.