About the relationship between eyebrow movements and Fo variations

Speech production is always accompanied by facial and gestural activity. The study is part of a broader research project on how head movements and facial expressions are related to voice variations in different speech situations. Ten normal subjects were recorded while reading aloud answering yes/no questions, and dialoguing with an interviewer. Rapid rising-falling eyebrow movements produced by the subjects as they spoke were associated with Fo rises in only 71% of the cases. This suggests that eyebrow movements and fundamental frequency changes are not automatically linked (i.e., they are not the result of muscular synergy), but are more a consequence of linguistic and communicational choices. Note also that 38% of the eyebrow movements were produced while the subject was not speaking. Thus, eyebrow movements may also serve as back-channel signals or play a role in turn-taking during conversation.