Towards a sustainable approach for sound absorption assessment of building materials: Validation of small-scale reverberation room measurement

The research and development phase of sound absorptive building materials by designers, engineers, acoustic consultants and architects need tools for fast, inexpensive preliminary comparison tests on products or acoustic systems. The existing methods exhibit some drawbacks: the impedance tube (IT) is not suitable for 3D systems, while the full-scale reverberation room (FSRR) requires test samples of large dimensions. To overcome these limitations, this work aims to explore the capabilities of small-scale reverberation rooms (SSRR) of about 3 m3 located at Politecnico di Torino in evaluating the randomincidence sound absorption coefficient. In order to define the range of application and reliability of the method, the considered factors are the sample area and its orientation on the room floor. Four different materials have been tested by applying IT, FSRR and SSRR. The absorption coefficients data obtained with SSRR are compatible with the FSRR benchmarking in the 400–5000 Hz frequency range for three porous materials, and in the range 1000–5000 Hz for the thin rigid material. Therefore, the SSRR can be considered as a reliable alternative for the sound absorption characterization in these ranges for this kind of materials, leading to several benefits. Among them, samples with reduced size can be evaluated with a cheaper equipment in a short time, increasing the overall economical sustainability of the measurement process; in turn, this can encourage designers and architects to perform acoustical measurements since the very early research and development phase, leading to an overall reduction of design costs and improved product quality.