Investigation of errors and uncertainty in low-frequency impedance tube measurements

Abstract

August2025School of ArchitectureThe accuracy of impedance tube measurements can be improved by determining the acoustic conditions within the impedance tube prior to introducing a sample for test. By measuring the empty impedance tube, the influence of environmental changes on critical parameters can be quantified. Low-frequency dissipation is estimated using Bayesian inference to incorporate into a transfer function model, reducing error when measuring samples. Previous work has focused on a frequency range of 1.5 kHz - 5 kHz; the subject of this study is a lower frequency range (sub-1.5 kHz) using larger sized impedance tubes. The empty tube model is then used to validate the acoustic performance of jute and thermoplastic starch-based microslit panel absorbers. By determining conformity of alternative-material acoustic elements to modeled behavior, and including acoustic testing in the design process, the viability of sustainable material substitutions can be determined.M