Bayesian characterization of porous media using three-microphone tube method in extended frequency ranges

TL;DR

This paper extends the frequency range for measuring acoustic parameters of porous media using a three-microphone method and Bayesian inference to accurately estimate impedance and propagation characteristics.

Contribution

It introduces a Bayesian approach to unwrapping phase discontinuities in broadband acoustic measurements with multiple microphones in a cylindrical tube.

Findings

Bayesian inference effectively estimates unwrapped propagation coefficients.

The method accurately captures transfer function behavior.

Extended frequency range improves porous media characterization.

Abstract

The characteristic impedance and the propagation coefficient are among the most important parameters for evaluating the acoustic performance of porous materials. This work investigates the influence of cylindrical modes in an impermeable tube and applies multiple microphones distributed along the tube circumference within the three-microphone framework to extend the valid frequency range of characteristic impedance measurement. During the extended broadband measurements, discontinuities or phase jumps are observed in the experimentally measured propagation coefficient of the porous material under test. A Bayesian inference is applied in a sequential manner to estimate the unwrapped propagation coefficient and characteristic impedance. The results demonstrate that the inferred parameters accurately capture the behavior of the transfer function, allowing accurate parameter estimation.