Towards an Unsupervised Entrainment Distance in Conversational Speech using Deep Neural Networks
Table 2: Correlation between emotional bond and various measures; TP: therapist-to-patient, PT: patient-to-therapist  ∗p<0.05 indicates statistically significant (strong) correlation
['Measure', 'Pearson’s correlation  [ITALIC] ρ', 'Pearson’s correlation  [ITALIC] p-value∗']
In this experiment, we compute the correlation of the proposed NED measure with the patient-perceived emotional bond ratings. Since the proposed measure is asymmetric in nature, we compute the measures for both patient-to-therapist and therapist-to-patient entrainment. We also compute the correlation of emotional bond with the baselines used in Experiment 1. We test against the null hypothesis H0 that there is no linear association between emotional bond and the candidate measure. This negative sign is consistent with previous studies as higher distance in acoustic features indicates lower entrainment. However, the therapist-to-patient NED does not have a significant correlation with emotional bond. A possible explanation for this finding is that the emotional bond is reported by the patient and influenced by the degree of their perceived therapist-entrainment. Thus, equipped with an asymmetric measure, we are also able to identify the latent directionality of the emotional bond metric. The complexity measure (Baseline 2) also shows statistically significant correlation, but the value of ρ is lower than that of the proposed measure.