The measurement principle of an impedance tube (also Kundt’s Tube) method involves generating a sound wave in a hollow tube filled with the porous material under investigation, where sound energy is partially absorbed and reflected. By analysing sound pressure levels at different positions along the tube, the method allows for the calculation of the material’s sound absorption coefficient, providing valuable insights into its acoustic properties for various applications. The Impedance Tube allows for precise measurements of sound absorption coefficients and impedance in accordance with ISO and ASTM standards. Additionally, it facilitates sound transmission loss measurements using the Transfer Function Method, which separates incident and reflected energy from the measured transfer function to estimate the acoustic properties of the tested sample within the tube.