## 6 Results and Discussions  
### Results and Discussions of Questionnaires Data  
The average GUESS value for phase one, which consists of 100 responses, is 32.85. For phase two, which has 111 responses, the average GUESS value is 38.58. The average GUESS value in phase two is higher than that in phase one, indicating that, on average, the players in phase two prefer the level recommendation mechanism. In addition to the average value, we statistically examined which phase can provide players with a superior gaming experience. Table 3 shows that the average GUESS values of the players in phase two follow a normal distribution, while those in phase one do not. Therefore, we used a Mann-Whitney U test to assess the significance of the difference in the GUESS results between the two phases. The \(p\)-value of the Mann-Whitney U test shows a significant difference between phase one and phase two, with the latter outperforming the former. Moreover, we compared each group's GUESS value with the midpoint value of 32. The Wilcoxon signed-rank test reveals that the GUESS value for the players in phase one does not significantly differ from the midpoint value. However, the average GUESS value for the players in phase two significantly exceeds the midpoint value of 32, as shown by a one-sample \(t\)-test. In summary, the average GUESS value in phase two was higher than that in phase one, indicating that the players in phase two had a better gaming experience. In addition, it was significantly higher than the midpoint value of 32. Consequently, these results indicate that players will have a better gaming experience in an FPS game with GPR-DDA. In Figure 4, we present the trend in our GUESS values across the two phases. The dark green and dark blue lines represent the trend of the average GUESS values in the two phases. Dots on the dark blue line represent the selected audio cue volumes in phase one. The light-colored area indicates the region where all error bands are connected using smooth lines. The granularity of the audio cue volume in phase two was finer than in phase one, with a similar population of participants as in phase one, meaning that some levels might have been played by only one person. This led to the error band area in phase two not being continuous. In phase two, the maximum and minimum audio cue volumes provided by GPR-DDA were 82 and 3, respectively, resulting in a shorter data range than in phase one. From Figure 4, we observe that the overall trend of GUESS values in phase two is higher than in phase one, indicating that players found the game more enjoyable under the control of GPR-DDA in phase two. In addition, we found that the average GUESS values in the ranges of 20 to 30 and 45 to 70 in phase two were not only higher than those in phase one but also more stable, which may indicate that these two ranges are the most reasonable settings for our players. Moreover, there is a noticeable decline when the audio cue volume exceeds 70, with a sharp peak around 80, which can be considered an outlier. We speculate \begin{table}
\begin{tabular}{l c c c} \hline \hline  & \multicolumn{2}{c}{**GUESS**} \\  & Phase One & Phase Two & \\ \hline Mean value & 32.85 & 38.58 & \\ Standard deviation & 6.84 & 6.59 & \\ Shapiro-Wilk test & 3.49 \(\times\) 10\({}^{-3}\) & 0.69 & \\ \(p\)-value 1  & 3.49 \(\times\) 10\({}^{-3}\) & 0.69 & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of results between phase one and phase two, as well as each phase and the midpoint. that an audio cue volume above 70 causes significant discomfort for players, leading them to consider the game as less enjoyable. Our results support the idea that GPR-DDA can provide a better gaming experience than linearly changing enemy audio cue volume. These results answer our **RQ 1:**_Can players have a positive gaming experience when a DDA mechanism is implemented through game volume?_ Therefore, when considering the goals of a DDA mechanism, balancing both designer preference and player performance is preferable.