# Call Redistribution for a Call Center Based on Speech Emotion Recognition
## 3 Algorithm for Call Redistribution Based on Speech Emotion Recognition  
As mentioned earlier, in this research, one presumption was that the urgency of the call correlates with the caller's emotional state reflected through speech. Our focus was on emergency call centers and health care centers for elderly people. Aiming to recognize more urgent callers among them, we have proposed the ranking of five basic emotions. So, basic emotions with negative valence (fear, anger and sadness) reflect unpleasantness of the speaker and our presumption was that those speakers have a health, or any other, more urgent problem. 4. Calls are processed in the new order which is obtained after their emotion labeling based on SER (and ASR) and redistribution according to the proposed emotion ranking, i.e., the priority vector. Firstly, all callers that are recognized as afraid are processed, after them angry callers and so on. In the end, the callers recognized as joyful are processed. The final goal of the redistribution is reduction in waiting time for the callers recognized as the priority. Let us denote the waiting time \(t_{1i}\) of a caller \(i\) without SER and call redistribution, where \(i=1,\ldots,C\) and \(C\) is the number of calls received at the same moment. Then, \(t_{2i}\) denotes the waiting time of a caller \(i\) after SER and call redistribution (after application of the proposed algorithm). The objective function is: \[\max\sum_{i=1}^{C}t_{1i}-t_{2i},\] (2) according to the priority vector \(p\). The objective function is formulated as to maximize waiting time reduction for the callers recognized as the priority regarding the priority vector \(p\). So, the goal of call redistribution is to maximize waiting time reduction for the caller \(i\), if the caller \(i\) is set as priority regarding the vector \(p\). In our experiments this is the case for the caller recognized as being afraid--fear is in first place in the priority vector \(p\). Afterwards, the objective function maximizes the waiting time reduction for the caller recognized as being angry, since anger is in second position in the priority vector \(p\). Figure 2: Proposed call redistribution based on SER. The call processing and the proposed algorithm are intended to be a part of a client-server application based upon computer-telephone integration (CTI). The main part of the application is running on the server side located on a remote computer. A client side is located at a call center. When a call is received, if there is at least one free operator, the call is answered immediately. In the case all operators are busy at that moment, the client side initiates a connection with the server which is waiting for clients. After the connection is established, a new session is started and the client sends a recorded speech sample of the call. On the server side, the feature vector is extracted for a received speech record and it is forwarded to SER module which classifies it into one of the predefined emotion categories. If a new call is received at a call center within a period of 30 s, the client sends the recorded speech sample of the second call and steps 1 and 2 of the algorithm are performed. The established session lasts as long as there are new calls within the time frame of 30 s, which is chosen as the overlapping time between two consecutive calls. When there are no more calls within the specified time period, all calls processed during the current session of client-server communication are redistributed according to the  
Figure 3: Block diagram of the proposed algorithm. proposed emotion ranking. The call redistribution is intended to be applied on a finite number of calls received in a short period of time while all the operators are busy. In the experiments, the situations of three, five and seven simultaneously received calls were considered. Let us denote them as group of calls.