No abstract

In an industry field, the acoustic characteristics such as a resonance frequency and an acoustic damping ratio are often required. The response test due to a random noise wave and the sweep test due to a sinusoidal wave can be performed in those cases. In vibration theory, it is well known that the peak value at resonance is inversely proportional to the damping ratio. Is it true even in the acoustic theory? If it can be true the acoustic damping ratio can be obtained simply by the peak sound pressure level after the relation between the peak value and the damping ratio is examined only once. In this study, the sound pressure level of the one dimensional duct with the perforated plate will be calculated by the transfer matrix method in various parameters such as the aperture ratio, the hole's length and the set position of the plate. These calculations are conducted for the first mode, the second mode and third mode. And the relation between the peak value and the damping ratio are examined.