PURPOSE: To obtain the sound absorber which has superior sound absorption characteristics over a wide frequency range by forming the sound absorber in multi-layered structure.
CONSTITUTION: A sound wave 6 is entered into a 1st air-permeable layer 1; and part of it is absorbed by the vibration of the 1st layer and the rest is passed through a sound absorbing material 2 and absorbed as a sound wave 6'. Further, the remaining sound wave 6' is absorbed by the resonance of the 2nd layer 3. The sound in the intermediate and high frequency range is absorbed by the vibration of the 1st layer and a 1st sound absorbing material and the sound in the low frequency range is absorbed by the resonance of the 2nd layer, so the sound absorption characteristics are obtained over the entire range.
TAKEWA HIROYUKI
TAMURA TADASHI
SATO KAZUHIDE
