Experimental comparison of various excitation and acquisition techniques for modal analysis of violins

Abstract

For decades, modal analysis has been a tool to gain insights in the vibrational and acoustical behavior of music instruments. This study provides a critical comparison of various experimental modal analysis approaches with the violin as a case study. Both contact and non-contact excitation and different acquisition approaches are considered. The influence of different boundary conditions (clamped, supported, free/free) on the vibrational response of the violin is investigated. The response is analyzed to extract relevant modal parameters (frequency, damping and mode shape) within the frequency range of 0–1000 Hz. The performance of the different approaches is evaluated in terms of (i) signature vibration modes, (ii) experimental reproducibility, (iii) contact requirement and (iv) cost of required equipment. Two optimal approaches are proposed for performing modal analysis on violins: a contact method for use in the violinmaker’s practice, and a non-contact method for use with fragile instruments.