From Overt Gesture to Covert Micro-Movement: Kinematic-Acoustic Trade-Offs and Internal Cueing in Art Song Performance

Art song performance requires singers to communicate textual and musical intensity through economical visible action. Larger rehearsal gestures may support phrase direction and breath organization, but they can appear stylistically excessive in recital contexts. This study examines the transition from overt gesture to covert micro-movement as a measurable kinematic-acoustic coordination problem. A single singer-researcher performed a phrase window from Wolf’s Ganymed under three within-performer conditions: Neutral, Overt, and Compressed. Two smartphone videos were processed using OpenCap to extract left shoulder flexion, left elbow flexion, and pelvis tilt, while synchronized audio was analyzed in Praat for intensity, fundamental frequency, and harmonicity-to-noise ratio. Reflexive logs documented task focus and perceived inhibition after each take. Results show that Overt singing reorganized upper-limb behavior, especially elbow motion, while Compressed singing reduced visible arm and elbow range without simply returning to Neutral. Mean intensity and central pitch span remained broadly stable, whereas mean harmonicity decreased from 9.34 dB in Neutral to 6.38 dB in Overt and 4.95 dB in Compressed. The findings indicate that compressed gesture may preserve internal cueing but may also remove mechanical impulse or introduce inhibition load.