Evaluating a scale model reverberation room for sound absorption coefficient measurements: A cost-effective alternative

The sound absorption coefficient (SAC) is a key parameter in acoustic simulation and treatment of enclosures. Among SAC measurement methods, reverberation rooms are a preferred method for their versatility, but require significant volumes, specimen sizes, and investment. This study assessed the capability of a 1:6 scale model reverberation room (SMRR), based on the full-scale reverberation room (FSRR) at the Universidad Nacional Autónoma de México (UNAM), to perform SAC measurements and reduce dimensions and costs. A hybrid methodology based on the impulse response (IR) method was developed in compliance with ISO 354, ASTM C423, and SAE J2883 standards. IRs were measured within the FSRR and the SMRR using maximum-length sequence (MLS) and logarithmic sine sweep (LSS) signals with two different test materials. SACs extracted from both IRs were compared using non-parametric tests on matching measurement pairs in both enclosures. No statistically significant differences were found for MLS comparisons, and the correlation coefficient indicated a strong monotonic association between both datasets. These findings suggest the potential of SMRRs for SAC measurements as a cost-effective alternative. However, further refinement of the scale model and studies on IR acquisition methods are needed to enhance its reliability.