# Dynamic Range Compression and the Semantic Descriptor Aggressive
## 4 Perceptual Listening Experiments
### Listening Experiment 1 Method
#### 4.1.2 Statistical Analysis of Experiment 1 Results  
A two-way repeated measures ANOVA was run to determine the effect of compression settings and the interaction effect and compression settings of the two songs on perceived distortion. [PERSON]'s test of sphericity indicated that the assumptions of sphericity had been violated for the two-way interaction between the song and settings \(\chi^{2}(2)=73.13\), \(p=0.001\). Therefore, a Greenhouse-Geisser correction was applied (\(\varepsilon=0.580\)). [PERSON]'s test of sphericity indicated that the assumptions of sphericity had not been violated for the effect of the settings \(\chi^{2}(2)=48.45\), \(p=0.081\). Simple main effects were run and showed that there was no statistically significant two-way interaction between the songs and settings on perceived distortion., \(F\) (8,128) = 0.648, \(p=0.653\). There was, however, a statistically significant effect of the settings on perceived distortion, \(F\) (8,128) = 50.97, \(p<0.001\). Post-hoc analysis with a Bonferroni adjustment showed the mean distortion scores for the 4:1 and all-buttons settings were statistically significantly higher than the scores for no compression (\(p<0.001\)). In addition, the mean distortion scores for the all-buttons settings were statistically significantly higher than the scores for the 4:1 ratio settings (\(p<0.001\)). Within the four different time constant settings used for both 4:1 and all-buttons, there was no statistical significance. A second two-way repeated measures ANOVA was run to determine the effect of the compression settings and the interaction and compression settings of the two songs on perceived aggression. Again, [PERSON]'s test of sphericity indicated that the assumptions of sphericity had been violated for the two-way interaction between the song and settings \(\chi^{2}(2)=53.99\), \(p=0.028\); thus, a Greenhouse-Geisser correction was applied (\(\varepsilon=0.531\)). [PERSON]'s test of sphericity indicated that the assumptions of sphericity had not been violated for the effect of settings \(\chi^{2}(2)=27.98\), \(p=0.081\). Simple main effects were run and showed that there was no statistically significant two-way interaction between the songs and settings on aggressive sound quality, \(F\) (8,128) = 0.301, \(p=0.886\). There was, however, a statistically significant effect of settings on aggressive sound quality, \(F\) (8,128) = 69.26, \(p<0.001\), suggesting that settings have a statistically significant effect on aggressive sound quality. Post-hoc analysis with a Bonferroni adjustment showed the same statistical significance between no compression and the two ratio settings as reported previously for distortion. Again, there was no statistical significance within the four different time constant settings used for either 4:1 or all-buttons, meaning that, in the current study, different time constant settings have no significant effect on the perception of distortion or an aggressive sound quality. The mean scores for aggressive and distortion were analyzed to assess if there was a statistically significant correlation between the scores. Both variables (aggressive and distortion) for both songs were normally distributed, as assessed by a Shapiro-Wilk test (\(p>0.05\)); thus, the variables were investigated for correlation. [PERSON]'s product-moment correlation was run to determine the relationship between perceived aggressive and distortion scores and the results show that there is a strong correlation between the mean scores for aggressive and distortion, which is statistically significant for song one (\(r=0.960\), \(n=9\), \(p=0.001\)) and song two (\(r=0.983\), \(n=9\), \(p=0.001\)). A scatter plot of the mean scores for aggressive and distortion for both songs is illustrated in Figure 5, where the correlation between the two can be clearly observed. Correlation between the aggressive scores and the roughness features extracted from the vocal files was investigated by running [PERSON]'s product-moment correlation.