Comparison of prediction methods for sound absorption of chairs using scale model measurements

The sound absorption of chairs in various architectural spaces has a significant influence on the reverberation time; therefore, several studies have been dedicated to characterizing the chair absorption. To date, various laboratory measurement methods have been proposed for predicting the sound absorption coefficients of larger seating blocks based on the measurement of a small number of chairs. Among these, four well-known methods have been widely cited: the standard ISO 354 methods in two editions, the K & K method proposed by Kath and Kuhl, and the perimeter-to-area (P/A) method developed by Bradley. However, there is currently no universally accepted standard measurement method for determining chair absorption, and the data quoted in the literature are not directly comparable because they are widely dispersed over time. Additionally, discrepancies in the chair type, measurement setup, and room conditions make it difficult to compare their prediction accuracies. In this study, laboratory methods including two alternative methods for predicting the sound absorption coefficients of chairs are investigated using 1/15-scale model measurements. The validity of the laboratory methods is discussed in comparison with the in-situ measurement results in a model hall. Consequently, the P/A method is estimated to be the most accurate method for predicting the sound absorption coefficients of various finite chair blocks.