15. The mobile face-to-face interaction monitoring device according to claim 1 , wherein the meta-linguistic information processor comprises: a feature extractor for extracting prosodic features of the sound signals; and a pattern analyzer for determining interaction pattern among the interactants in the conversation group, based on the turn and at least one of the prosodic features.
17. The mobile face-to-face interaction monitoring device according to claim 15 , wherein the pattern analyzer determines sparseness based on a quantity of non-speech turn in a given time.