A highly refined bowing technique is essential for producing rich and expressive sounds during violin performances. This study investigates how bowing proficiency is reflected in the spatial directivity of radiated sounds among three groups of violinists: amateurs, nationally active professionals, and internationally acclaimed performers. Performances were recorded using 42 microphones arranged spherically around each player to capture their directional sound-radiation patterns. The results show that as bowing proficiency increases, sound radiation becomes more directionally focused toward the lower front at low frequencies (approximately 400 Hz) and toward the front at mid-frequencies (approximately 1 kHz). By contrast, forward-upward radiation at high frequencies (approximately 3 kHz) is consistently observed across all groups, except for a few amateur players. These findings suggest that advanced bowing techniques are required to effectively excite the back plate and ribs—which contribute to downward and frontal sound radiation, respectively—because these plates are not in direct contact with the bridge and are less easily subjected to vibration. Furthermore, because spatial directivity is not readily perceived by the ear, its visualization offers a valuable pedagogical tool by providing visual feedback that complements auditory perception, particularly for less-experienced violinists.
Maki et al. (2025) studied this question.