# Timbre Preferences in the Context of Mixing Music
## 7 Discussion and Conclusions
The probability density function, shown in Figure 7, also suggests a substantial impact of the user interface on the final settings of this slider: all of the sliders have local maxima at their maximum and minimum settings, with most sliders having a pronounced one at the minimum, but OER actually has fairly equal maxima at both extremes (the median PT for the low and high halves of the OER settings are 1.84 and 5.4, respectively). \begin{table}
\begin{tabular}{c c c} \hline \hline
**FX** & **Median PT** & **Slider Range in PT** \\ \hline Slope & 21.04 & 145.5 \\ OER & 4.63 & 7.3 \\ Inharmonicity & 219.67 & 1550.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Median slider setting in units of PT (Perception Threshold). In the special bi-modal case of OER (odd/even ratio), the median PT values for the slider range 0.0–0.5 and 0.5–1.0 are 2.05 and 5.91, respectively. FX = timbre manipulations. Figure 7: Probability density plot of slider distributions, X = Slider Value, Y = Probability density estimate. The bandwidth of the kernel smoothing window = 0.08. OER = odd/even ratio. Despite multiple statements from participants about difficulties with the inharmonicity manipulation (\"only used 4 th slider, if the sound was high pitched\", \"I wanted to make'smoother' sounds, did not like the 4 th slider, very inharmonious!\", \"alien-slider (4) was fun, but I didn't use it much\", etc...), according to the median PT of the slider settings, the most perceptually relevant timbral change was apparently induced by it. This is despite the fact that the harmonicity slider actually being left at its zero position most often out of the four (see Table 5). The main timbral change was achieved predominantly with drastic changes in inharmonicity (in relation to its PT) compared with the changes used in the other sliders. A notable restriction to the usage of PT is that the given values theoretically only represent the given value from the zero position of their slider, with all other sliders being set at zero as well, so they only ever represent a rough estimate. This means that the PT expression of the median values can only represent the perceptual distance from the starting sound (the sawtooth). Secondly, the perceptual impact of, for example, inharmonicity would most likely be reduced for higher settings of slope due to the higher partials, which are affected by the inharmonicity slider, being attenuated by the slope manipulation. Regarding the clustering of the mixing settings, the perceptual impact of OER also contextualizes the results of the \(k\)-means/silhouette readings of the slider data. The clustering seems to indicate two strong clusters, which are predominantly characterized by their OER value, something that looks equally convincing in Figure 7. To test whether this binary split of the OER settings represents two distinct mixing clusters, a mixed effects model was run in R, with the OER settings (rounded to either zero or one) as the response variable, slider settings for Slope, Distortion, and Inharmonicity as fixed effects, and participant id as random effects. This did not show any power of the other sliders in predicting OER, implying that there is no distinct grouping of the other settings related to the chosen OER values. This in combination with the low perceptual impact of OER supports the suggestion that the distinct clustering in the \(k\)-means analysis is predominantly due to the affordances of the user interface (UI). Alternatively, it could be interpreted as there is a preference for those two extremes over more middling values since 7.9 PTs of the range should still be clearly audible, but the effect is still subtle; hence participants chose the extremes because intermediate settings were less distinct.