A Single Number Index to Assess Selected Acoustic Parameters in Churches with Redundant Information

The paper presents an innovative approach for the index assessment of the acous-
tic properties of churches. A new formula for an approximate single number index
to assess selected acoustic parameters of church interiors, such as reverberation time
(RT), speech intelligibility index (RASTI) and music clarity index (C80), is presented
in the paper. The formula is created by means of the Singular Value Decomposition
(SVD) method. An innovative approach for calculating the weights of partial in-
dices is shown by solving the problem of redundant information, i.e., the system of
overdetermined linear equations, using a computed pseudoinverse matrix. The new
procedures for calculating the values of three partial indices and the single number
index to assess selected acoustic parameters are presented. The proposed method
was verified by measurements in several selected churches.