Modifications of phonetic labial targets in emotive speech: Effects of the co-production of speech and emotions

This paper describes how the visual characteristics of some Italian phones (/'a/, /b/, /v/) are modified in emotivespeech by the expression of the "big six" emotions: joy, surprise, sadness, disgust, anger, and fear. In this research we specifically analyze the interaction between the articulatory lip targets of the Italian vowel /'a/ and consonants /b/ and /v/, defined by phonetic-phonological rules, and the labial configurations, peculiar to each emotion. This interaction was quantified on the basis of the variations of the following parameters: lip opening, upper and lower lip vertical displacements, lip rounding, anterior/posterior movements (protrusion) of upper lip and lower lip, left and right lip corner horizontal displacements, left and right corner vertical displacements, and two asymmetry parameters, calculated as the difference between right and left corner position along the horizontal and the vertical axes. The first aim of this research is to quantify the modifications of the lip articulatory parameters due to the emotions; the second aim is to analyze the parameters which are subject to phonetic-phonological constraints and are consequently less influenced by emotions. The results are useful to define the emotivespeechproduction models and are presently employed in researches concerning audiovisual speech synthesis (Talking Heads).