1. A method for automatically performing voice interaction analytics by identifying concepts in a plurality of interactions between customers and agents of a contact center in a plurality of intervals, the method comprising: identifying, on a processor of a voice interaction analytics system, the interactions occurring in one of the plurality of intervals; creating, on the processor of the voice interaction analytics system, a plurality of sentences from the identified interactions; computing, on the processor of the voice interaction analytics system, a saliency of each the sentences; pruning away, on the processor of the voice interaction analytics system, sentences with low saliency for generating a set of informative sentences; comparing, on the processor of the voice interaction analytics system, the sentences of the set of informative sentences to identify a plurality of groups of similar sentences; generating, on the processor of the interaction analytics system, a plurality of sentence clusters, each of the sentence clusters corresponding to a concept of the concepts and comprising a group of similar sentences based on the interaction analytics of the plurality of interactions between customers and agents of the contact center; computing, on the processor of the voice interaction analytics system, a saliency of each of the sentence clusters; naming, on the processor of the voice interaction analytics system, each of the sentence clusters; identifying, on the processor of the voice interaction analytics system, a plurality of sentences of an interaction of the interactions; comparing, on the processor of the voice interaction analytics system, each of the sentences of the interaction with the plurality of sentence clusters to identify a plurality of matching sentence clusters; labeling, on the processor of the voice interaction analytics system, the interaction with a plurality of matching concepts, each matching concept corresponding to one of the matching sentence clusters based on the interaction analytics of the plurality of interactions between customers and agents of the contact center in a plurality of intervals; and displaying, on a display device, the number of interactions labeled with each of the matching concepts during the one of the plurality of intervals based on the interaction analytics of the plurality of interactions between customers and agents of the contact center.