Comparison of standing wave ratio method and transfer function method for measuring sound absorbing properties of 3d printed samples
Measurements in the impedance tube are very useful as they enable the measurement of sound absorption for normal incidence sound, under controlled conditions. Due to the small size of the samples (a few centimetres in diameter) they are frequently used in the development of new materials. Alternative solutions usually demand the construction of large samples, which is more difficult and expensive. Moreover, the impedance tube method can be carried out with relatively simple equipment in a normal room and does not need specialised test chambers [1] A lot has been written about the accuracy of the measurement method, the effect of the mounting condition, etc. [2 4] However, a majority of these studies are concerned with open porous and homogenous materials.