A Double Synthetic Index to Evaluate the Acoustics of Churches

Several authors have proposed indices to synthesize the acoustics of a space, especially of concert halls.
Meanwhile, a few studies have focused on the acoustics of worship spaces. The peculiarities of these last
ones have shown distinctive characteristics. The increasing interest for the acoustics of worship spaces
justifies the formulation of indices to synthesize the results of acoustic studies in these buildings too.
This paper proposes a double synthetic index to evaluate the acoustics of a church. The index is obtained
combining the average values of seven parameters generally considered in studies of architectural acoustics.
The differences between requirements for music and speech in churches suggest to consider different
optimal values of the selected parameters for different kinds of sound. A double synthetic index has been
defined to synthesize the acoustical properties related to the music and to the speech separately. The
validity of this double index is then assessed, comparing its values with subjective preferences captured
through listening tests. The index, which is proposed and validated in this paper, aims to be an instrument
to show synthetically the acoustical characteristics of a church to people with low knowledge in acoustics.