# Influence of the Sound Source's Position on the Stage on the Speech Perception in the Auditorium
## 3 Results
### Measurement of the Quality of Speech In Situ Versus in a Laboratory  
Figure 11 shows the speech quality scores obtained in situ and in the laboratory. Comparing the results for Decor #1 obtained in situ and in the laboratory, it can be seen that the scores obtained in the laboratory were significantly lower; however, the trend was maintained. The difference between the results in situ and those obtained in the laboratory varied, depending on the listener's position, from 0.52 (R02) to 0.86 (R07), with an average difference of 0.71. The standard deviation at these points for the in situ measurements was S (R02) = 0.62 and S(R07) = 0.57, while the average value for all listener positions was S = 0.14. The lower MOS values were a result of the microphones used for recording, as well as listening through headphones. Therefore, a correction related to the mean squared deviation of the results was introduced, which improved the consistency of the results (#1 \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Listener** & \multicolumn{2}{c}{**\#1**} & \multicolumn{2}{c}{**\#2**} \\ \cline{2-5}
**Position** & **MOS** & \(\sigma\) & **MOS** & \(\sigma\) \\ \hline
1 & 4.34 & 0.63 & 3.86 & 0.77 \\
2 & 4.33 & 0.67 & 4.23 & 0.78 \\
3 & 4.03 & 0.66 & 3.93 & 0.81 \\
4 & 4.15 & 0.65 & 4.10 & 0.69 \\
5 & 4.13 & 0.58 & 4.03 & 0.79 \\
6 & 4.03 & 0.58 & 3.84 & 0.81 \\
7 & 3.96 & 0.57 & 3.59 & 0.78 \\
8 & 4.21 & 0.63 & 3.92 & 0.70 \\
9 & 4.11 & 0.60 & 3.87 & 0.68 \\
10 & 4.04 & 0.63 & 3.65 & 0.89 \\
11 & 4.01 & 0.66 & 3.61 & 0.72 \\
12 & 3.91 & 0.68 & 3.54 & 0.86 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: The mean value of the speech quality assessment (MOS) and standard deviation (\(\sigma\)) for two types of decoration for 12 listener positions. Figure 10: Results of the subjective quality assessment (MOS) for two types of decoration at Implant Centrum. (Corrected)). After the correction was performed, the differences in the results decreased to values between 0 and 0.18, with an average difference of 0.009. For comparison purposes, test signal recordings were made for the R04 listener position using an artificial head, and the evaluation was performed under laboratory conditions. The results obtained for the different positioning of the sound source S for the male and female voice, along with the averaged result, are shown in Figure 12.  
Very good agreement can be observed between the results obtained in the in situ and laboratory measurements at the R04 listening position when the test signal was recorded using an artificial head (AH). The greatest difference appears for the location of the sound source S03. The difference in the MOS value is 0.3, which is practically within the standard deviation of the listener ratings, which was 0.64 for this point (R04) and source position S03 (Table 6). In turn, comparing the results of the measurements made in the laboratory for the recordings made with the microphone and the artificial head, it can be seen that the  
Figure 11: Results of the subjective quality assessment (MOS) for in situ and laboratory measurements. Figure 12: Results of the subjective quality assessment (MOS) for in situ and laboratory measurements (Lab) and test signal recorded using an artificial head (AH). maximum difference reaches a value of 0.81 (sound source location S03), while the minimum difference is 0.42 (for S02). Analysing the results obtained in this task, it can be seen that there were slight differences in the evaluation of the quality of the male and female voice at all measurement points, i.e., listener positions. For Decor #1, the maximum difference in the evaluation of male and female voices was 0.38 at listener position R03, and for Decor #2, this difference was equal to 0.21 for R01. In contrast, the minimum difference values were 0.15 at point R06 for #1, and 0.02 at R05 for #2. A non-parametric Wilcoxon-Mann-Whitney test was used to test whether the observed differences in the results were statistically significant.