Comparison of sound absorption characteristics measured by impedance tube method and ensemble averaging technique on porous clay bricks

摘要

Porous clay brick (PCB) is one of the alternative materials used to solve heat and noise pollutions due to its inexpensiveness [1]. However, PCBs’ acoustic properties have only been the focus of a few studies because the measurement techniques are challenging. The impedance tube method or tube method [2] is one of the techniques commonly used to measure the sound absorption coefficient of materials, but the sample preparation and mounting are challenging [3]. The tube method requires that the sample have a size and shape that fit the tube rim to prohibit air leakage. Regarding sample preparation and mounting, creating a PCB with the correct size and sharp edges is nearly impossible after firing because the random additive destitutions make shrinkage unpredictable. Moreover, cutting or resizing a PCB is still problematic because the clay particles will chip. The authors tried to apply the ensemble averaging (EA) method to overcome this difficulty, and they obtained satisfactory results [4]. However, they also wanted to compare the results with standard methods to confirm how sound absorption characteristics have similarities or differences. Thus, this study compares the sound absorption characteristics between the tube and EA methods on PCBs.