## 4 Discussion  
The conclusions of the first experiment are in accordance with other studies [29]: (i) the mean of the continuous pleasantness assessment is the most important predictor of the global pleasantness assessment (ii) the recency effect and trend effect both influence the retrospective global assessment of the pleasantness of a sound sequence. Nevertheless, the recency effect that is observed in the first experiment tends to disappear in the second experiment. Two hypotheses are formulated:  
* The sound sequences of the second experiment are less contrasted and more complex than the controlled sound sequences used in the first experiment. This attenuates the conclusions concerning a recency effect for the sound pleasantness assessment of real sound sequences. Moreover, as in the first experiment, the focus was to observe the influence of the temporal structure in an environment, so sound markers or events have been removed. Such events, as semantic content, are suspected to significantly influence the overall rating of the sound environment [43]. These events and markers, present in the second experiment, might have masked the recency and trend effects that were observed in the first experiment. * The video content might have helped participants to analyze the sequences of the second experiment as a whole, thus attenuating the recency effect. Figure 7: Estimated global pleasantness from \(P_{\text{estimated}}\) versus assessed global pleasantness for the 10 sequences. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Equations** & **Explaned Variance** & \(\mathbf{R}^{2},\mathbf{F},\mathbf{p}\), and RMSE Values** \\ \hline \(21.5-0.24\)\(\times\)\({}_{50}\) & 58\% & \(R^{2}=0.63\), \(F\)(\(2.8\)) = \(13.4\), \(p<0.01\), \(RMSE=0.58\) \\ \(27.8-0.33\)\(\times\)\({}_{\text{mean}}\) & 54\% & \(R^{2}=0.59\), \(F\)(\(2.8\)) = \(11.6\), \(p<0.01\), \(RMSE=0.77\) \\ \(18.6-0.18\)\(\times\)\({}_{\text{eq}}\) & 15\% & \(R^{2}=0.25\), \(F\)(\(2.8\)) = \(2.53\), \(p=0.15\), \(RMSE=1.06\) \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Different models to estimate global pleasantness from physical measurements. Finally, contrary to the first experiment, \(GP\) values are globally higher than the \(P_{\text{mean}}\) values. This might be the consequence of the visual factor on global pleasantness appreciation, with the help of the video. The positive effect of the video on the overall pleasantness rating has already been shown in [21; 22; 44]. But then, the fact that \(GP\) values are relatively higher than \(P_{\text{mean}}\) values, would suggest that the visual effect has no influence on the continuous assessment of the sound pleasantness, which needs to be investigated in future studies. The estimated instantaneous pleasantness is accurately estimated by the sound level measurements in Section 3.2.1, although some discrepancies remain unexplained. Attempts to take into account the spectral content of the signal or the typology of the sound sources, did not improve the explained variance. The visual content might also explain the remaining discrepancies between the sound pleasantness estimates, as a closer look at the ending of sequence five, and the beginning of the sequence six, suggests. These sub-sequences both correspond to environments that are visually unpleasant, and precisely at these instants, the models, which do not account for the visual settings, over-estimate the sound pleasantness rating given by the participants. Another explanation for the remaining discrepancies relates to the high correlations observed between sound pleasantness and sound intensity: participants might have relied on noise intensity to assess the sound pleasantness over the continuous appreciations. Including a better description of the sound environment, for example, with specific sound source descriptors, might enhance the instantaneous estimated sound pleasantness.