Analysis of lip vibrations during brass instrument performance using digital image correlation and intraoral measurement

Conventional methods of measuring lip vibrations during brass instrument performance often use mouthpieces that differ in shape and material from those used during actual playing. This can lead to vibration characteristics that do not accurately represent real conditions. Therefore, this paper proposes a novel measurement technique that captures lip vibrations using a standard performance mouthpiece. Specifically, a fiberscope camera and a strobe LED were inserted into the oral cavity to image the inner surface of the lips during performance. A random speckle pattern was applied to the lips, and strobe imaging was performed using the intraoral camera system to visualize the periodic lip vibrations. Digital image correlation (DIC) was used to conduct displacement analysis on the acquired images, allowing observation of lip surface displacements. The analysis revealed that lip displacement amplitude tends to decrease in the high register compared to the low register. Furthermore, vibration propagation along the surface of the lower lip was observed. This method is expected to contribute to brass pedagogy, validate artificial lip models, and provide valuable data for the numerical simulation of brass instrument blowing mechanics.