Three ToBI-based measures of prosodic entrainment and their correlations with speaker engagement

Entrainment is the propensity of conversational partners to align different aspects of their communicative behavior. In this study we present three novel measures of prosodic entrainment based on intonational contours as defined by the ToBI conventions for prosodic description. Each of these measures estimates the similarity of contours used by speakers in different ways: by means of the perplexity of n-gram models, the Levenshtein distance, and the Kullback-Leibler divergence measure. We report significant correlations between each of these measures and manual annotations of a number of social variables related to the level of engagement of speakers, in a corpus of task-oriented dialogues in Standard American English.