Ensemble averaged absorption characteristics of materials using an in-situ technique: investigations on influence of wind-induced noise

An in-situ measurement method based on ensemble averaged surface normal impedance using p-p and p-u sensor, i.e., EA method, has been proposed by some of the authors. The measured results of absorption characteristics are possibly affected by wind-induced noise caused by such as a wind from air conditioner outlets when measurement of sound absorption characteristics is conducted in-situ. In this paper, the authors experimentally investigated the influences of wind-induced noise on the absorption characteristics obtained by the EA method with p-p and p-u sensor. Firstly, as a normal environment, sound absorption measurements of glass wool under two conditions to generate wind are conducted: opening the window of a room or operating the air conditioner. Result shows the absorption characteristics are almost same regardless of the presence or absence of wind under the normal environment. Next, measurement are performed by changing the wind speed around the sound receiving point gradually using a circulator. The faster wind speed became, the larger deviation of measured values became. Even if the wind speed is similar, sound absorption characteristics may change depending on the wind direction and other factors.