Coordination of eyebrow movement with speech acoustics and head movement

Studies on the relationship between eyebrow movement and other aspects of speech production have focused on large, discrete movements of the eyebrows. Using integrated optical and electromagnetic point tracking, we measured eyebrow movements relative to the skull with a high level of precision. These data in combination with a correlational analysis method that accommodates varying phasing between the signals enabled the investigation of the relationship between continuous eyebrow movements, speech acoustics, and head movements. Our results show that there was a correlation between eyebrow movements and speech acoustics, though there was notable variation within and across participants. The relationship between eyebrow and head movements was much closer, with a strong correlation between eyebrow movement and subsequent head movement, which held across participants. We discuss the implications for theories of gestural control in speech production.