# Historically Based Room Acoustic Analysis and Auralization of a Church in the 1470s
## 1 Introduction
Churches are often large, complex buildings with vaulted ceilings and spaces such as choirs, transports, chapels, or apses. This may lead to the formation of acoustic subspaces [30] that are characterized by room acoustic parameters significantly deviating from the rest of the space. For instance, such subspaces may result in varying perceived reverberation as indicated by EDT within the apse, or degradation of clarity far from the chancel. In some cases, the structural separation of such subspaces serves a liturgical purpose. For example, smaller chapels may be dedicated for funeral procedures, or the choir for the hourly services of a monastic congregation. Distinct liturgical purposes may coincide with distinct liturgical activities, such as the monassical service being characterized by the chanting of the congregation. As the liturgical activities benefit from proper acoustics, the acoustics in a given subspace must be evaluated with respect to the activities at that location. [PERSON] et al. [7] presents such research regarding the cathedral in Toledo, which indicates that the acoustical properties in the subspaces supported the activities performed there. Similar results regarding the choir have been seen in several research projects [31; 32; 33]. The interaction between religious rites and acoustics is not yet fully understood, especially when spatial variations within churches are considered. It has been established that the acoustic requirements of worship spaces differ from conventional acoustic guidelines [7; 34], but there is not yet a strong consensus on what these requirements are. As of yet, the international standard on measurements of room acoustic parameters, ISO 3382, does not contain guidelines for acoustic measurements of worship spaces. Although there exist established methods for such measurements [35], the lack of an official standard may lead to variations in the measurement methods which in turn cause issues when comparing the results of such measurements. In addition, the lack of guidelines regarding acoustic requirements may cause issues when acousticians are tasked with constructing new worship spaces, or improve existing spaces. The analysis in this paper, where room acoustic parameters within the abbey are combined with a discussion of the religious purposes of various subspaces, may help shed light on these questions. The goal of this paper is twofold: First, describing the process of constructing a historically accurate archeo-acoustical digital model of an abbey church in Sweden. Second, presenting the analysis of its room acoustic properties. To start, some background information on the abbey is briefly presented. Then, certain aspects of the historically based digital reconstruction are discussed. This description shows that the conclusions of the acoustical analysis rely on sound historical research, and act as inspiration for future, similar projects. Subsequently, recordings of material for auralization are briefly presented. The process of acoustic simulation is described, and the simulated acoustic field is analyzed in detail both globally and locally within acoustic subspaces.