In this chapter, the authors provide an overview of some of their experimental work on accompanist gestures of clarinettists. They explore these gestures from two perspectives: first, by analysing the role of expressive movements in music performance; and second, by investigating the influence of such gestures on audience members’ perception of music. The analysis of musical performance is therefore a broad research subject based upon knowledge and methods from several domains, which complement research on speech and gesture. The movements and gestures did influence the experience of tension for observers, especially at important points in the musical score, and the effect of seeing the musician depended upon the individual musician’s movement style. R. Vines and colleagues have generated applications for functional data analysis in multi-modal research with music, and conceptual tools for research in musical emotion and temporal dynamics. Body movements served to convey the performers’ musical interpretations of the score.