The effect of micro-changes in the pluck trajectory on the sound of an acoustic guitar
For guitar testing methodologies, this work highlights the importance of controlling plucking trajectory to ensure consistent acoustic measurements.
This study investigates how micrometer-scale changes in plucking depth affect the sound of an acoustic guitar, finding that low depth results in weak sound, while increased depth raises loudness, reduces inharmonicity, and shifts timbre. The effect varies with plectrum material.
This study explores how micro-changes in the plucking trajectory of a guitar pick influence the sound of an acoustic guitar. Using a state-of-the-art robotic plucker, a series of measurements has been performed, where the plectrum was moved towards the instrument by a step of 192 micrometers, resulting in an increased attack depth. It has been analysed how the effect of these changes is reflected in loudness, timbre, harmonic content and how the sound progresses during decay. This methodology has been repeated for guitar plectra made from six different materials to investigate how the pick itself influences the effect of a change in the plucking trajectory. The results of the study show that at a low depth the string is not fully excited resulting in weak and markedly altered sound. The range of this effect changes with the mechanical properties of the plectrum material. After this range an increase in depth results in an increase in sound loudness, a decrease in inharmonicity and noisiness and a shift in timbre where the sound becomes fuller in low frequencies and rougher. Presented findings help to understand the nuanced relationship between plucking trajectory and acoustic output. They provide important insights regarding the importance of plucking in guitar testing methodologies, showing that the mech