All participants heard at least a slight difference between the different audio fragments with respect to both pitch contour and speaking rate. The semantic content of a sentence had a clear effect on valence but not on arousal.
Speaking Rate
A faster speaking rate is associated with a higher level of activity. So, for a CUI to be recognized as actively taking part of a social interaction, it must use a speaking rate with adequate pace.
Pitch Contour
All patterns ending on a risen pitch are related to the higher mean valence ratings. The higher mean ratings for dominance are associated with pitch contour patterns that end with a pitch below neutral. This is in line with human speech were dominance is often radiated by using a lower tone of voice. According to these results, this idea also applies to synthetic voices.
Where mean valance is highest at the first pitch contour, mean dominance is lowest. This continues throughout the whole series of contour patterns. Applying these insights to the earlier mentioned use of deeper voices to convey power, indicates that perceived power is simultaneously perceived as less pleasurable. For a CUI to have a social and pleasurable conversation, it thus seems important to exclude lower tones of voice.