Identifying the Instrumental Gesture Parameters Affecting the Timbral Quality of a Classical Guitar

In this study, we explore the timbral properties produced in a classical guitar from different instrumental gesture parameters performed by different guitarists. We determine the parameters that significantly affect the tone through design of experiments and statistical analysis. We represent the tonal response as three numerical values, namely the spectral centroid, spectral flux, and spectral rolloff. We implement a full factorial design with three factors, namely the angle of attack, plucking position, and the fret-string combination. We also explore the effect of varying physiology of guitarists. We verified through this study that the errors introduced by varying physiology of guitarists significantly affect the tonal quality produced with a p-value of less than 0.01% for two responses. This is further verified by the computation of accuracy for different models since the average error on the test set reduced by around 22% when we construct a unique model for each individual rather than for all individuals with varying physiology. We also identified that the spectral centroid response greatly captures the tonal quality of the classical guitar, having an average error on the test set that is at least 51% lower compared to the other responses.