## 3 Methodology
### Model Validation
These connections occur at the levels of the choir floor and the upper tribune, in the spaces arranged for the visual connection between both parts of the building, considered in the modelling as flat virtual surfaces with an absorption coefficient close to 100%. Three options were considered for the scattering coefficients. In general, a default value of 10% was allowed in all octave bands for all materials, except for those with an irregular real surface, which were simulated using flat surfaces, as is the case of altarpieces. In this case, variable dispersion coefficients of between 30 and 80% were considered for the octave bands. For the spaces connecting with the rest of the novitiate units, a surface was modelled with an absorption coefficient close to 100% and a dispersion of 1%. Figure 5: San Luis de los Franceses church. Colours correspond to different materials. Following the comparison of the results of the in situ measurement and the computer-simulated model, it can be concluded that the model adopted for the church of San Luis de los Franceses adequately reproduces the acoustic behaviour of the room in its current state. Figure 6 shows the JND differentials of the different parameters, obtained as the difference between the mean values of the parameters at the different frequencies, from the modelling and the in situ measurement, and divided by the JND value obtained in the measurement from the indications given in of UNE-EN ISO 3382-1 standard. In general, the results are between \(-1.00\) and \(+1.00\) for the different frequencies. The value of early lateral energy fraction (\(J_{\text{LF}}\)) is that with the lowest adjustment as this parameter is difficult to simulate. However, the IACC\({}_{\text{E}}\) value is adequate, except for in the 4000 Hz band. The JND differential for reverberation time is higher than the rest of the parameters, obtaining results between \(-2.00\) and \(-4.00\) JND, possibly due to the arrangement of coupled spaces. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Material** & **Area (\%)** & **125 Hz** & **250 Hz** & **500 Hz** & **1 kHz** & **2 kHz** & **4 kHz** \\ \hline \multirow{2}{*}{Plaster *} & \multirow{2}{*}{58.60} & 0.12 & 0.12 & 0.11 & 0.13 & 0.15 & 0.17 \\  & & 0.10 & 0.10 & 0.10 & 0.10 & 0.10 & 0.10 \\ \multirow{2}{*}{Marble [30]} & \multirow{2}{*}{23.10} & 0.10 & 0.10 & 0.10 & 0.20 & 0.20 & 0.20 \\  & & 0.10 & 0.10 & 0.10 & 0.10 & 0.10 & 0.10 \\ \multirow{2}{*}{Altarpieces [29]} & \multirow{2}{*}{10.90} & 0.12 & 0.12 & 0.15 & 0.15 & 0.18 & 0.18 \\  & & 0.30 & 0.40 & 0.50 & 0.60 & 0.70 & 0.80 \\ \multirow{2}{*}{Wooden door [30]} & \multirow{2}{*}{0.80} & 0.14 & 0.10 & 0.06 & 0.08 & 0.10 & 0.10 \\  & & 0.10 & 0.10 & 0.10 & 0.10 & 0.10 & 0.10 \\ \multirow{2}{*}{Glass [32]} & \multirow{2}{*}{3.2} & 0.04 & 0.04 & 0.03 & 0.03 & 0.02 & 0.02 \\  & & 0.10 & 0.10 & 0.10 & 0.10 & 0.10 & 0.10 \\ \multirow{2}{*}{Opening} & \multirow{2}{*}{1.70} & 0.99 & 0.99 & 0.99 & 0.99 & 0.99 & 0.99 \\  & & 0.10 & 0.10 & 0.10 & 0.10 & 0.10 & 0.10 \\ \multirow{2}{*}{Ceramic flooring [30]} & \multirow{2}{*}{0.80} & 0.02 & 0.02 & 0.03 & 0.03 & 0.04 & 0.05 \\  & & 0.10 & 0.10 & 0.10 & 0.10 & 0.10 & 0.10 \\ \multirow{2}{*}{Organ [33]} & \multirow{2}{*}{0.9} & 0.12 & 0.14 & 0.16 & 0.16 & 0.16 & 0.16 \\  & & 0.30 & 0.40 & 0.50 & 0.60 & 0.70 & 0.80 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Finishes: materials, references, surface (%), and absorption (up) and scattering (down) coefficients. * Material used for the adjustment. Figure 6: JND differentials spatially averaged versus frequency octave band for the acoustic parameters evaluated: difference between the simulated and measured results divided by JND of the measured value.