## 2 Materials and Methods
### Proposed Calculation Method
#### 2.3.1 Noise Components Within the Block Harmonic
\[\text{C}_{\text{Corr,BH1}}=1-[0.000060551\times(\text{F}_{\text{in}}+\text{F}_ {\text{out}})] \tag{5}\]  
The correction factor is subsequently interpolated to a correction function that adjusts the correction factor according to a generalized gradient of the loudness ratio over the rotational speed of the engine. In this way, the correction function can be used to adjust the masking threshold in the frequency range of the block harmonic over the rotational speed of the engine. Analyses have shown that the torque profile alone is not sufficient to account for the rpm-dependent loudness ratio between torque levels. It can be assumed that additional secondary effects such as the frequency or the vehicle velocity take place. Figure 7: Loudness ratio up to the power limit over the tractive force acting on the tires. In order to interpolate the correction function, the correction factor is adjusted at selected supporting points with a weighting factor according to Moll [38], where the first supporting point was slightly adjusted. Additionally, to account for effects in the early run-up phase, a supporting point at 0 rpm was added. Table 3 shows the supporting points and the corresponding weighting factor. The value \(\mathrm{n_{pl}}\) represents the engine's rotational speed at the power limit. Figure 8 shows the calculated and measured loudness ratio of the first block harmonic between 50 Nm and 310 Nm torque using the interpolated correction function. The dashed lines indicate a 10% deviation. The calculated loudness ratio shows a high conformity with the loudness deviation between 50 Nm and 310 Nm. The deviation between the calculated and measured loudness ratio remains below 10% over the entire investigated speed range. Thus, the interpolation of the correction factor can be used to adjust the masking threshold for orders in the order range of the block harmonic. Increased sound pressure levels and loudness in the frequency range of the block harmonic will also affect the masking threshold at surrounding frequencies. So, in addition to the rpm-dependent adjustment, the correction factor needs to be applied to the surrounding frequency range. For the adjustment of the 2-dimensional masking threshold maps, the frequency range to which the correction function is applied is modeled using a Tukey window [39], where the upper and lower frequency limit is chosen according to the bandwidth of the block harmonic and the spreading of masking derived from excitation  
Figure 8: Correction function to adjust the masking threshold at 50 Nm to the masking threshold at 310 Nm (circles indicate supporting points, dashed lines indicate 10% deviation). \begin{table}
\begin{tabular}{c c c c c c} \hline
\begin{tabular}{c} (\(1-\mathrm{C_{corr,BH1}}\)) \\ \end{tabular} \\ \hline \end{tabular}
\end{table} 
Table 3: Supporting points and weighting factors according to [27]. patterns for narrow band noise [3]. In this way, the masking effect of the increased sound pressure level of the block harmonic is considered. In order to account for the effects of the second block harmonic, the same procedure is used to derive a regression model and subsequent calculation of a correction function.