# Validation of the Developed Psychoacoustic Model for Sound Quality Valuation of Washing Machines
## 3 Results and Discussion
\begin{table}
\begin{tabular}{l l l l l l l l} \hline \hline
**Washing** & **Operation** & **L\({}_{\text{Aeq,T}}\)** & **Roughness** & **Sharpness** & **Loudness** & **Tonality** & **Fluctuation Strength** \\
**Machine** & **Modes** & **(dB)** & **(Asper)** & **(Acum)** & **(Sone)** & **(t.u.)** & **(Vacil)** \\ \hline \multirow{3}{*}{1} & FILL & 44.6 & 0.710 * & 1.520 * & 2.330 * & 0.1410 ** & 0.0084 * \\  & WASH & 32.2 & 0.343 & 0.890 * & 0.620 * & 0.0327 * & 0.0109 * \\  & SPIN & 55.8 ** & 1.300 & 1.910 * & 6.616 & 0.0762 & 0.0075 ** \\ \hline \multirow{3}{*}{2} & FILL & 45.8 ** & 1.020 ** & 1.740 ** & 3.340 ** & 0.0784 * & 0.0259 ** \\  & WASH & 41.2 ** & 0.815 ** & 1.440 ** & 1.860 ** & 0.0654 & 0.0317 ** \\  & SPIN & 53.4 & 1.500 ** & 1.980 & 6.670 ** & 0.0560 * & 0.0062 \\ \hline \multirow{3}{*}{3} & FILL & 44.0 & 0.813 & 1.610 & 2.540 & 0.0784 * & 0.0193 \\  & WASH & 34.8 & 0.153 * & 1.090 & 0.950 & 0.0897 ** & 0.0316 \\ \cline{1-1}  & SPIN & 51.9 & 1.200 * & 2.350 ** & 6.250 * & 0.0971 ** & 0.0053 * \\ \hline \hline \end{tabular}  
*—best (lowest) achieved values within each psychoacoustics parameter; **–worst (highest) achieved values within each psychoacoustics parameter.  
\end{table} 
Table 6: Measurement results using binaural measuring technology. Figure 3: Psychoacoustic parameters: (**a**) Loudness; (**b**) Sharpness; (**c**) Roughness; (**d**) Fluctuation strength; (**e**) Tonality. As all evaluated psychoacoustic parameters are measured in different units, it was important to standardize the measured values so that all parameters have comparable ranges. The weights of the monitored psychoacoustic parameters for the evaluated operating modes of washing are derived from a previous evaluation of washing machines [12]. The weighting values were derived from the correlation between the objective and subjective evaluations. The determined weights are presented in Table 5. To determine the weights of psychoacoustic parameters, we used a correlation coefficient, which is an effective way to identify which parameters have the greatest impact on the final response or subjective perception of sound by users. The weights of the parameters were determined directly from the size of the correlation coefficients, the higher weights are assigned to those parameters that have higher absolute values of the correlation coefficients. In this way, all weights have been normalized to a range of 0 to 1, and their sum is 1. The largest value of the weight factor achieved in the FILL operating mode belongs to the Sharpness parameter (0.40). In the WASH mode, it is the Roughness parameter (0.30), and finally, in the SPIN operating mode, there are two parameters, namely Roughness/Loudness (0.24). On the other hand, the lowest values close to zero were reflected in the FILL mode for the Roughness parameter (0.04) and in the WASH mode for the Tonality parameter (0.07). The ranking of the washing machine compiled on the basis of a subjective evaluation (ranking based on the average number of points achieved in the questionnaire) and the calculated quality index (see Equation (5) and Table 5) for the evaluated operating modes of washing are given in Table 7. We rate the washing machine with the lowest \(S_{Qi}\) sound quality index as the most acceptable from the user's point of view. In FILL mode, the lowest value of \(S_{Qi}\) was calculated for Machine-\(I\) (1.06), and the highest (1.32) was for Machine-\(2\). In WASH and SPIN mode, the result was the same, with the same ranking of washing machines (1. place--Machine-\(I\); 2. place--Machine-\(3\); 3. place--Machine-\(2\)). The lowest \(S_{Qi}\) values for the above operating modes were calculated for Machine-\(I\) (WASH--0.36, SPIN--2.13) and the highest \(S_{Qi}\) for Machine-\(2\) (WASH--0.90, SPIN--2.31). Based on a questionnaire survey, the washing machine that received the highest number of points was the best rated. In the FILL mode, Machine-\(3\) received the highest number of points (8.5), while Machine-\(I\) received the lowest number (4.9).