| Summary: |
Absorber material has characteristic of acoustic that reflect and absorb sound wave.
Absorption by porous material is very useful to reduce the sound power level that occurs so as to
reduce the noise in the room. The sound absorbtion coefficient of the Acoustic Sandwich
Composite (ASC) was determined by a two-microphone impedance measurement according to
international standard ASTM 1050-98. Dimension of The ASC consist of 1 core and 2 skin with
diameter 100 mm. Skin on front side designed has 5 hole (d=10 mm) and used 4 different
thickness of polyurethane foam (PU-Foam) that is 10, 20, 30 and 40 mm used as core of ASC. The
skin on both sides of sandwich composite made from continuous and chopped agave sisalana fibre
reinforced polyester with thickness 5 mm. Value of Noise Absorption Coefficient (NAC) is given
from 0 to 1, which means sound absorption is none in value 0, and sound absorption reaches the
maximum in value 1 on frequency range 0 Hz -1.6 kHz. This case, it is shown on the foam with
thickness 30 mm is good in the low frequency range with the higest value of NAC is 0,46. The ASC
designed of thickness 30 mm foam core can raise reach value of the NAC in the low frequency
(400 Hz-1000 Hz), highest value 0.80 at frequency 800 Hz. The ASC of thickness 10 mm foam
core to be optimum for middle frequency (1000 Hz-1600), highest value 0.89 at frequency 1200
Hz.
|