Backchannel relevance spaces

This contribution introduces backchannel relevance spaces – intervals where it is relevant for a listener in a conversation to produce a backchannel. By annotating and comparing actual visual and vocal backchannels with potential backchannels established using a group of subjects acting as third-party listeners, we show (i) that visual only backchannels represent a substantial proportion of all backchannels; and (ii) that there are more opportunities for backchannels (i.e. potential backchannels or backchannel relevance spaces) than there are actual vocal and visual backchannels. These findings indicate that backchannel relevance spaces enable more accurate acoustic, prosodic, lexical (et cetera) descriptions of backchannel inviting cues than descriptions based on the context of actual vocal backchannels only