定狀波裝置에 의한 라왕合板 의 吸音과 音響임피이던스

Acoustic Absorption and Impedance of Lauan Plywood by Standing Wave Apparatures

The acoustic absorption coefficie nt and acoustic impedance of 3, 5, 7 plywoods for zero degree incident sound, were measured by the standing wave method, which is more simple in the setup and give more accorate results than do the other measured methods. The dependence of the acoustic absorption coefficient and acoustic impedance on the thickness of the sample itself and the backing air gap in the sample plate was investigated experimentally in the frequency range from 100 to 1800 Hz, and the following result was obtained. 1. The acoustic absorption coefficient increased with increasing vs. frequency for 3, 5, 7 plywoods without backing air gap 2. The acoustic absorption coefficient increased with backing air gap than without backing air gap in band of low frequency 3. The high acoustic absorption coefficient transposed the band of low frequency with increasing plywood thickness and backing air gap. 4. Normal acoustic impedance decresed with incresing as a function of frequency