PURPOSE: To improve the sound absorbing rate of a low frequency tone by specifying the weight average diameter of powder to be mixed into a foamed body.
CONSTITUTION: The weight average diameter of the power 2 mixed into the foamed body 1 consisting of a high molecular material is set up to ≤1000 μm. Namely, flow resistance of the powder is increased in inverse proportion to the weight average diameter of the powder, and in the range of ≤1000 μm, the sound absorbing rate of a low frequency tone is suffiently effectively increased. When the shapes of originally complexedly connected cells 3 are furthermore complicated and a flow resistance value per unit thickness is increased, the sound aborbing rate of the low frequency tone can be increased. Thereby even if the thickness of the sound aborbing material is thin, the high sound aborbing rate of the low frequency tone can be obtained.
OKUDAIRA YUZO
UMEOKA KAZUAKI
KURIHARA YOSHITAKA
NAKAI TAKASHI
