3. The system according to claim 2 , wherein the classifier groups conversations that have a similar pattern of the smoothed difference data string to classify a plurality of conversations.
4. The system according to claim 3 , wherein the classifier converts the smoothed difference data string to a classification data string representing the variation of values for identifying when the first speaker predominantly speaks, when the second speaker predominantly speaks, or when the first speaker and the second speaker both speak, in order to classify the plurality of conversations based on the pattern of the classification data string.