Conference_programme: 18.6 - Acoustics of reverberation chambers
Lecture: Experimental verification of how relative air humidity influences the results of sound absorption coefficient measurements in model tests
Author(s): Majchrzak Aleksandra, Baruch Katarzyna, Przysucha Bartosz, Szeląg Agata, Kamisiński Tadeusz
Summary:
Performing sound absorption coefficient measurements in a model reverberation chamber requires scaling all the elements with given similarity criteria. One of them is air absorption, in scaled models most commonly regulated by relative air humidity, which is usually kept below 5%. However, the process of drying the air is time consuming and difficult to perform, which makes the measurement procedure problematic. This raises a question if there is a possibility to change or simplify it. \nTo answer this question the authors performed a series of sound absorption coefficient measurements in a one-to-eight scale reverberation chamber for different values of relative air humidity (3% - 35%). Eleven diverse materials used for the measurements were chosen based on their flow resistivity. Gathered data was then statistically tested, using the one-way analysis of variance and post-hoc tests, which enabled to choose three representative materials for further measurements. In the main study sound absorption coefficient of the chosen materials was measured with better resolution of relative air humidity (5% to 45%, 2-3% step) and a profound statistical analysis was carried out to verify the initial assumption. \nThe results show that the influence of relative air humidity on the final results of the measurements is negligible and therefore the measurements can be performed in a regular air humidity of a chamber. As statistical analysis shown, to improve the accuracy of the measurement additionally, one can repeat the procedure in several different air humidity values and then take an average result. Proposed solution, which is a substitution for commonly used air drying, allows considerable savings of time and efforts while performing the measurements.\n
Corresponding author
Name: Ms Aleksandra Majchrzak
e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Country: Poland
