# Call Redistribution for a Call Center Based on Speech Emotion Recognition
## 4 Simulation and Experimental Results
The comparative results of average waiting time in all three experimental settings (3, 5, and 7 simultaneously received calls) regarding the callers in all five emotional states, are shown in Figure 4. As the callers in the state of fear have the highest priority, their average waiting time is significantly reduced in all experimental settings, even up to twenty times in the case of three simultaneously received calls, ten times in the case of five simultaneously received calls, and six times reduced in the case of seven calls. Angry callers are given the second priority in redistribution, so in all experiments the decrease in their average waiting time is achieved. In the case of three and five simultaneously received calls, the waiting time after redistribution is reduced to less than half of the waiting time before redistribution. In the case of seven simultaneously received calls, the waiting time is reduced by one third of the initial waiting time. From experimental results shown in Figure 4, it can be noticed that sad callers will have a moderate decrease in waiting time after the proposed call redistribution. The absolute value of waiting time reduction is the biggest in the case of seven simultaneously received calls, but the relative value of reduction is the biggest in the case of five calls and it amounts to about 18% of the initial waiting time. As can be observed from Figure 4, callers in a neutral state have increased waiting time after call redistribution, about 1 min increase in the case of three and five simultaneously received calls, and about 2 min increase in the case of seven simultaneously received calls. Joy is marked as the emotion with the lowest priority, which is why callers featuring joy are put at the end of the caller's queue. It causes a significant increase in waiting time for the caller in a state of joy, about twice as longer waiting time after the proposed call redistribution in all experimental settings. Table 5 shows the waiting time reduction for five emotional states after SER and the proposed call redistribution is applied, in all experimental settings (with 3, 5 and 7 simultaneously received calls) in a simulated call center. Time reduction is calculated as difference between the average waiting time \begin{table}
\begin{tabular}{c c c} \hline \hline
**Emotion** & **without the Proposed Algorithm [min][s]** & **after Application of SER and Call Redistribution [min][s]** \\ \hline fear & 6:39 & 0:54 \\ anger & 6:33 & 4:11 \\ sadness & 7:16 & 6:24 \\ neutral & 6:12 & 8:49 \\ joy & 6:10 & 11:40 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Average waiting time when 7 calls are received simultaneously while all operators are busy. Figure 4: Average waiting time for five emotional states, without and after application of the proposed call redistribution. without the call redistribution and the average waiting time after application of SER and the proposed call redistribution:  
\[\Delta t_{e}=\tilde{t}_{1e}-\tilde{t}_{2e}, \tag{3}\]  
where \(\tilde{t}_{1e}\) denotes the average waiting time for a caller in the emotional state \(e\) without SER and call redistribution, \(e\) denotes one of the five emotional states (fear, anger, sadness, neutral and joy), and \(\tilde{t}_{2e}\) denotes the average waiting time for a caller in the emotional state \(e\) after application of SER and call redistribution. The positive values of waiting time reduction in Table 5 indicate the real reduction in waiting time after call redistribution, which is the case of the callers recognized as being in a state of fear, anger or sadness. Negative values of waiting time reduction indicate that waiting time after call redistribution is actually increased, which is the case of the callers recognized as being in a neutral or joyful state.