A rule-based backchannel prediction model using pitch and pause information

We manually designed rules for a backchannel (BC) prediction model based on pitch and pause information. In short, the model predicts a BC when there is a pause of a certain length that is preceded by a falling or rising pitch. This model was validated against the Dutch IFADV Corpus in a corpus-based evaluation method. The results showed that our model performs slightly better than another well-known rule-based BC prediction model that uses only pitch information. We observed that the length of a pause preceding a BC is one of the important features in this model, next to the duration of the pitch slope at the end of an utterance. Further, we discuss implications of a corpus-based approach to BC prediction evaluation.