4. The method of claim 1 , further comprising receiving contextual information used for detecting the emotion of the user, the contextual information comprising at least one of differential statistics, joint statistics, distance statistics, and statistics collected during a prior dialog between the user and the computing device, comprising (1) differential information of prosodic features, (2) temporal variation of emotion indicators inter-utterance, and (3) temporal variation of emotion indicators intra-utterance.
5. The method of claim 4 , wherein the differential statistics relate to a rate of change of prosodic values from one turn to another in the natural language dialog.