Response Variation in a Group of Acoustic Guitars

Dynamic testing was performed on a pool of guitars in the production facility of a major guitar manufacturer. The production process is highly automated, with the goal of improving quality and reducing build variation. However, no objective metric has yet been used to quantify the differences in the dynamic response of the instruments. We performed dynamic testing on the assembly line to measure the lower resonant frequencies of a pool of instruments. The standard deviations of the first two modes were a few percent of the mean, and the data suggest that a significant percentage of the variation is due to intentional differences in the species used for backs and sides.