# Historically Based Room Acoustic Analysis and Auralization of a Church in the 1470s
## 4 Room Acoustic Analysis
### Acoustics in the Nave  
Within the nave, the acoustic simulations aim first at characterizing the acoustics of the space itself and, second, at evaluating any difference between various source locations. As such, the data in this section are presented separately, according to the source position. The three source positions are in the gallery (point P1 in Figure 9, nuns' position), in the choir (point P2, monks' position), or in the nave, by the high altar (point P3). \(T_{20}\), EDT, and G results are shown in Figure 13. As the results in this section are in general spatially averaged, the standard deviations are also shown as an estimate of the spatial variations between listener positions. The average reverberation time in the reconstructed abbey is shown in octave band resolution Figure 13a. Results for the three different source positions are shown, and are very similar; also shown in the graph is a gray area delimiting values that are within 1 JND  
Figure 12: Images illustrating the dispersion of acoustic energy, as approximated by an acoustic particle model, over time. Subfigure (**a**) shows the progression when the source is located in the choir, and subfigure (**b**) shows when the source is located in the gallery. From top to bottom, the pictures show snapshots at 20 ms, 60 ms, 80 ms, and 120 ms.  
of the global average. All lines fall entirely within this area, indicating that there are no significant differences in the reverberation time in the wave depending on the location of the sound source; also shown in Figure 13d are the standard deviations of \(T_{20}\) for each of the source positions. These are shown together with the global JND for reverberation time. All standard deviations fall below the JND line, indicating that the variations of the reverberation time are on average imperceptible. This indicates that the late acoustic response within the naive was, in general, diffuse and not characterized by significant spatial variations. In general, the reverberation time is long, but comparable to similar spaces. \(T_{20}\) is significantly decreased compared to modern day measurements, as expected by the discussion in Section 3.1.1. In Table 2, the mid-frequency reverberation time (\(T_{m}\)) is shown together with measurement results from the modern day church (from in [43]) and some other Gothic churches around the Baltic Sea (from in [11]). These results allow for a basic comparison between the reconstructed abbey and similar spaces. \begin{table}
\begin{tabular}{l l l} \hline \hline
**Church** & **Volume (m3)** & \(T_{m}\) **(s)** \\ \hline Swedish church, current configuration & 29,000 & 7.79 \\ Swedish church, historical configuration & 29,000 & 5.15 \\ Church of our Lady, Krakow, Poland & 9500 & 6.5 \\ Church of St Thomas, Lipsk, Germany & 18,000 & 4.05 \\ Marien Church, Lübeck, Germany & 100,000 & 5.50 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Mid-frequency reverberation times for some Gothic churches in Northern Europe. Figure 13: Overview of room acoustic parameters in the reconstructed church. Results are shown for three different source positions in octave band resolution. **(a)** The average \(T_{20}\) and **(d)** its standard deviation. **(b)** The EDT and **(e)** its standard deviation. **(c)** The G and **(f)** its standard deviation. All standard deviations are shown compared to the global average JND of that parameter (dotted line). The gray areas in graphs **(a–c)** delimit values within 1 JND of the global average. Spatially averaged EDT values for each source position are shown in Figure 13b. Again, the gray area delimits values within 1 JND of the global average. The variations for different source positions are greater than those seen for \(T_{20}\), but only the results for the choir are significant compared to the JND. This difference is, however, small. Comparing the global EDT values to the guidelines proposed by [PERSON] et al [34] shows that the average EDT exceeds the recommended values for the reconstruction.