# Validation of the Developed Psychoacoustic Model for Sound Quality Valuation of Washing Machines
## 3 Results and Discussion  
In the present paper, subjective and objective analyses are proposed and correlated, in analogy with the methods proposed in the literature, in particular with reference to [43,44]. \begin{table}
\begin{tabular}{l l l l l l} \hline
**Operation Modes** & **Roughness** & **Sharpness** & **Loudness** & **Tonality** & **Fluctuation Strength** \\ \hline FILL & –0.08 & 0.86 & 0.36 & 0.39 & 0.42 \\ WASH & 0.96 & 0.33 & 0.85 & 0.23 & 0.82 \\ SPIN & 0.92 & 0.66 & 0.90 & –0.72 & 0.59 \\ \hline \end{tabular}
\end{table} 
Table 4: Pearson correlation coefficients [12]. \begin{table} \begin{tabular}{l l l l l l} \hline  & **Roughness** & **Sharpness** & **Loudness** & **Tonality** & **Fluctuation Strength** \\ \hline FILL & 0.04 ** & 0.40 * & 0.17 & 0.19 & 0.20 \\ WASH & 0.30 * & 0.10 & 0.27 & 0.07 ** & 0.26 \\ SPIN & 0.24 * & 0.17 & 0.24 * & 0.19 & 0.16 \\ \hline \end{tabular}   
* [noitemsep,topsep=0 pt]
On the basis of the correlation analysis, the sound sample assuring the best correlations between objective and subjective variables was identified and then used to develop psychoacoustic models. The correlation between subjective independent attributes and overall judgements was proposed. It is worth noting that in [22; 43], the subjective evaluation of all selected attributes well correlated with the global judgment. Three types of top-loading washing machines are evaluated in this article. During the measurement, the standardized washing program Cotton 60 \({}^{\circ}\)C--Energy Label declaration programmed was used on all evaluated washing machines. Three operating modes were assessed, namely FILL, WASH, and SPIN. The measured values of the monitored psychoacoustics parameters (Loudness, Sharpness, Roughness, Fluctuation strength, and Tonality) are graphically shown in Figure 3.  
Low-frequency noise, with a frequency range of 10 Hz to 200 Hz, has been recognized as a special environmental noise problem, particularly for sensitive people in their homes. Low-frequency noise is often emitted by household appliances and, from a psychoacoustic perspective, represents a problem, as described in the articles [45; 46]. The results of the objective evaluation of the equivalent sound pressure level L\({}_{\text{Aeq,T}}\) and psychoacoustics parameters for the evaluated types of top-loading washing machines and their operating washing modes are presented in Table 6.  
The best psychoacoustic parameter values vary depending on the operating washing mode. The lowest values of all psychoacoustic parameters (except for the fluctuation strength parameter) are observed in the WASH washing mode for all evaluated washing machines, as is also evident from the functions they perform within the individual operating modes of washing. Machine-2 shows the highest values for almost all evaluated psychoacoustic parameters, except for Tonality. For the Roughness and Loudness parameters, these values are the highest for all operating modes. Machine-3 achieves relatively high Sharpness values in SPIN mode (2.350), on the contrary, other psychoacoustic parameters are the lowest in SPIN mode. Machine-\(I\) has the lowest values for psychoacoustic parameters in WASH and FILL modes, except for the Roughness parameter in WASH mode (0.343) and Tonality in FILL mode (0.1410). From the measured values, we can conclude that, from the point of view of the evaluation of psychoacoustic parameters, the worst psychoacoustic parameters are achieved by Machine-2 and the best psychoacoustic parameters are achieved by Machine-\(I\).