20. A mobile face-to-face interaction monitoring method, comprising: scanning one or more mobile devices in a surrounding area and setting a conversation group; detecting sound signals in the mobile devices in the conversation group, relative to differences in positions of the mobile devices; creating volume topography based on the sound signals for each interactant in the conversation group; determining turn by using the volume topography; and extracting meta-linguistic context of interactants in the conversation group based on the turn, wherein the turn is a sound-signal segment where each interactant in the conversation group starts and ends the interactant's speech, wherein the volume topography is created by using a signature or feature vector of volume value(s) for the sound signals detected, and wherein the creating the volume topography based on the sound signals is performed by creating a quantity of n+l of the volume topography, where n is a number of the interactants in the conversation group, and wherein: each of the n-quantity of the volume topography created respectively corresponds to each of the n-number of the interactants, and the l-quantity of the volume topography created corresponds to non-speech or silent turns in the conversation group.
30. The mobile face-to-face interaction monitoring method according to claim 20 , wherein the extracting the meta-linguistic context of interactants in the conversation group based on the turn comprises: extracting features of the turn; extracting prosodic features of the sound signals; and determining interaction pattern among the interactants in the conversation group, based on the features of the turn and at least one of the prosodic features.