Exploring the differences between PU based in situ absorption results and the standardized reverberant room method
Several measurement techniques are available for determining the sound-absorbing properties of material packages. Kundt's tube method and the reverberant room method are the most commonly used techniques, and both are standardized. However, neither method can be used in situ.
Previous studies have shown that the PU in situ method can be applied across a broad frequency range (typically from 300 Hz up to 10 kHz) and on small samples (typically 0.03 m² to 0.38 m² or larger), while being minimally affected by background noise and reflections. Several studies have revealed that similar results to those obtained with Kundt's tube can be achieved, provided that measurements are performed under certain conditions.
A thorough comparison with the reverberant room method has not yet been conducted. This paper presents preliminary results from a comparison of the reverberant room method, the PU in situ method, and measurements with PU probes in a reverberant room. Several factors that may cause discrepancies among the methods are discussed. In addition, edge effects—commonly encountered with the reverberant room method due to the finite size of the sample—are visualized using 3D intensity measurements performed in a reverberant room.