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Description
While normal-incidence absorption can be measured with a simple impedance tube (ISO 10534-2), its random-incidence counterpart (ISO 354) assumes a level of infrastructure most university labs simply don't have. This paper first compares these two standardized methods with several non-standardized alternatives, weighing their accuracy, practicality, and cost in a summary table intended as a practical guide. It then addresses the specific case of small-scale reverberation rooms, evaluating a small, unmodified bathroom as a low-cost alternative to a dedicated reverberation chamber. The validity of this approach is assessed by comparing the absorption coefficients obtained in the adapted room with those measured in an impedance tube, across three sample configurations of increasing exposed area. The results show that compatibility between the two methods depends on two independent conditions: measuring above the room's Schroeder frequency, and using a sufficiently large sample area, neither being sufficient on its own. These findings provide a practical guideline for researchers with limited resources seeking to validate small-scale reverberation room measurements in non-dedicated spaces.