Impedance measuring device AcoustiTube

pressurelaboratory

Determination of sound absorption, reflection coefficients and impedance ratio of material samples. Impedance Tube The impedance tube AED 1000 – AcoustiTube® is a measuring system for determining the sound absorption coefficient, the sound reflection factor and the impedance ratio of materials in the laboratory on the basis of the transfer function method described in DIN EN ISO 10534-2, ASTM E1050 and DIN EN ISO 13472-2. In the impedance tube a plain sound wave is generated and sent against a sound absorbing specimen in front of a reverberant termination. The resulting sound pressure is measured by using two microphones in front of the material sample. The sound absorption coefficient of the material is determined by evaluating the incoming and reflected sound energy. Extension of Impedance Tube to Transmission Tube An extension of the impedance tube to the transmission tube allows the determination of the characteristic absorber values (wave number ka and characteristic impedance Za), the transmission coefficient and the sound insulation (transmission loss) by applying the Two-Load Method with 4 microphones according to ASTM E2611 (Transmission Matrix Method). On such basis, the insertion loss of mufflers (software for acoustic design of mufflers AcoustiCalc®-Silencer) and the diffuse sound absorption coefficient (software for acoustic design of sound absorbers AcoustiCalc® -Absorber), comparison to measurements in the reverberation chamber according to DIN EN ISO 354, especially rated sound absorption coefficient of the material according to DIN EN ISO 11654) can be computed directly.