Increasing measurement accuracy by estimating multiple dissipations for the impedance tube calibration

Impedance tube measurements, employing transfer function/matrix methods, are commonly used by acousticians to characterize the acoustic properties of materials in normal incident conditions. Sound dissipation in impedance tubes can impact the accuracy of measurement results. Various effects contributing to sound dissipation in tubes are studied and analyzed. This research investigates different dissipative effects and dissipation models. This paper uses model-based Bayesian inference to estimate critical parameters in multiple dissipations. The experiments involve using an empty impedance tube terminated with a rigid metal block. A hypothetical air layer in front of the metal block is assumed for establishing a prediction model in contrasting estimation results with theoretical values. The results incorporating dissipation models demonstrate a good match with the theoretical calculation of the air layer. Applying the estimated dissipations to actual resonator materials demonstrates a significantly improves measurement accuracy.