12th Annual Conference of the International Speech Communication Association

Florence, Italy
August 27-31. 2011

A Multimodal Analysis of Vocal and Visual Backchannels in Spontaneous Dialogs

Khiet P. Truong, Ronald Poppe, Iwan de Kok, Dirk Heylen

University of Twente, The Netherlands

Backchannels (BCs) are short vocal and visual listener responses that signal attention, interest, and understanding to the speaker. Previous studies have investigated BC prediction in telephone-style dialogs from prosodic cues. In contrast, we consider spontaneous face-to-face dialogs. The additional visual modality allows speaker and listener to monitor each other's attention continuously, and we hypothesize that this affects the BC-inviting cues. In this study, we investigate how gaze, in addition to prosody, can cue BCs. Moreover, we focus on the type of BC performed, with the aim to find out whether vocal and visual BCs are invited by similar cues. In contrast to telephone-style dialogs, we do not find rising/falling pitch to be a BC-inviting cue. However, in a face-to-face setting, gaze appears to cue BCs. In addition, we find that mutual gaze occurs significantly more often during visual BCs. Moreover, vocal BCs are more likely to be timed during pauses in the speaker's speech.

Full Paper

Bibliographic reference.  Truong, Khiet P. / Poppe, Ronald / Kok, Iwan de / Heylen, Dirk (2011): "A multimodal analysis of vocal and visual backchannels in spontaneous dialogs", In INTERSPEECH-2011, 2973-2976.