## 3 Results
### Descriptive Analysis of the Testing Data
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Parameters of the Design**} & \multirow{2}{*}{**Possible Options**} & \multicolumn{2}{c}{**Testing Data**} & \multicolumn{2}{c}{**Training Data**} \\  & & **N** & **\%** & **N** & **\%** \\  & & **(Total = 168)** & **(Total = 100\%)** & **(Total = 388)** & **(Total = 100\%)** \\ \hline \multirow{5}{*}{Diaphragm (Primary Unit)} & Polyethylene & 50 & 29.76\% & 141 & 36.34\% \\  & Terephthalate & 43 & 25.60\% & 98 & 25.26\% \\  & Polyetheretherketone & 40 & 23.81\% & 77 & 19.85\% \\  & (PEEK) & 40 & 20.83\% & 72 & 18.56\% \\ \hline \multirow{5}{*}{Type (Secondary Unit)} & No Secondary Unit & 36 & 21.43\% & 86 & 22.16\% \\  & Included & 36 & 21.43\% & 86 & 22.16\% \\  & Dynamic Unit/Moving & 48 & 28.57\% & 83 & 21.39\% \\  & Soil & 28.57\% & 100 & 25.77\% \\  & Balanced Armature Unit & 48 & 28.57\% & 100 & 25.77\% \\  & Planar Magnetic Unit & 36 & 21.43\% & 119 & 30.67\% \\ \hline \multirow{5}{*}{Magnet Type (Secondary Unit)} & No Secondary Unit & 36 & 21.43\% & 86 & 22.16\% \\  & Included & 34 & 20.24\% & 80 & 20.62\% \\  & N40 Grade & 35 & 20.83\% & 74 & 19.07\% \\  & N45 Grade & 30 & 17.86\% & 78 & 20.10\% \\  & N45 Grade & 33 & 19.64\% & 70 & 18.04\% \\ \hline \multirow{5}{*}{Voice Coils (Secondary Unit)} & No Secondary Unit & 36 & 21.43\% & 86 & 22.16\% \\  & Included & 36 & 21.43\% & 86 & 22.16\% \\  & Copper Wire & 45 & 26.79\% & 127 & 32.73\% \\  & Aluminum Wire with & 41 & 24.40\% & 71 & 18.30\% \\  & Copper Covered & & 27.38\% & 104 & 26.80\% \\  & Silver Wire & 46 & 27.38\% & 104 & 26.80\% \\ \hline \multirow{5}{*}{Diaphragm (Secondary Unit)} & No Secondary Unit & 36 & 21.43\% & 86 & 22.16\% \\  & Included & & & & \\ \cline{1-1}  & Polyethylene & 38 & 22.62\% & 83 & 21.39\% \\ \cline{1-1}  & Terephthalate & 48 & 28.57\% & 75 & 19.33\% \\ \cline{1-1}  & Polyetheretherketone & 39 & 23.21\% & 75 & 19.33\% \\ \cline{1-1}  & (PEEK) & & & & \\ \cline{1-1}  & PEEK + Polyurethane & 31 & 18.45\% & 69 & 17.78\% \\ \hline \hline \end{tabular}
\end{table} 
Table 5: _Cont._From the visualization, the relativity of the six indicators of the testing set had a descending ordered sequence, which was headroom (mean = 4.3155) > THD (mean = 4.2024) > signal-to-noise ratio (mean = 4.1905) > power of output (mean = 4.1845) > range of frequency response (mean = 4.1488) > impedance of the speaker (mean = 4.1369), while the best- and worst-performing indicators were headroom and impedance of the speaker, respectively. In essence, the best-performing indicator is shared with the training set, which reflects the alignment of the dataset. Although differences can be observed in the performance scores of the two sets of data, little variation can be observed in the six performance indicators. Therefore, adopting the data in the performance evaluation was reasonable. Hence, with respect to the relativity of the scores, performance ranking among the testing dataset can be deduced (Table 7), while similarity to ranks of the training set can be observed as well. Similar to the analysis of the training data, a correlation analysis between the design parameters and sound quality outcomes was performed in order to inspect the connection among the variables (Table 8). A close connection between the design parameters and sound quality outcomes can be observed, which indicates that meaningful linkages exist between the independent and dependent variables. Therefore, the data were sharing the same properties as the training data and thus suitable for the evaluation of the predictive performance of the developed formulations.