Assessing the acoustic properties of Roman Catholic churches: A new approach

Abstract The results of investigations and analyses of the acoustic properties of Polish Roman Catholic churches, using both the classic methods and the index method proposed by the authors, are presented in the paper. The different approach to church acoustic quality assessment is based on changing a large amount of information contained in mutually correlated input data, which are acoustic parameters obtained from the interior impulse response, into the set of independent components. Such transformation is possible due to Principal Component Analysis (PCA) and Singular Value Decomposition (SVD) applied in the paper. Later, the synthesis of independent components (partial indices) into one global index of church acoustic quality was performed by means of Comparative Multivariate Analysis (CMA). The verification of the proposed approximate method of church acoustic assessments was performed in eight Roman Catholic churches, investigated by the authors, objects of various cubic capacity, various ground plans and interior finishing. The single-number assessment using the global index, which is the function of several partial indices, provides complex information on church acoustics, which allows the ranking of objects and comparison of their acoustic properties. More accurate information on acoustic parameters in relation to the generally accepted optimal values are provided by partial indices, describing reverberation conditions, sounds of music, intelligibility of speech and external disturbances. The proposed global index can be used in a simple way in simulation investigations and in forecasting acoustic quality changes in churches, caused by new structural and material solutions during their acoustic adaptation or by taking into account the variable church occupation.