Air permeability and sound absorption coefficient changes from ultrasonic treatment in a cross section of Malas (Homalium foetidum)

Abstract We investigated the effect of ultrasonic treatment on Malas ( Homalium foetidum ) gas permeability and sound absorption coefficient using transfer function method. Results showed a longitudinal average Darcy constant 2.02 (standard deviation SD 0.72) for untreated wood 6.15 (SD 3.07) ultrasound-treated wood, increase 3.04 times. also determined coefficients in range 50 to 6.4 kHz NRC (noise reduction coefficient: value at 250, 500, 1000, 2000 Hz) Malas. Those values were 0.23 0.02) 0.13 0.01), respectively, while those ultrasonic-treated 0.28 0.14 0.02), 19.74% coefficient.