Maria’s research work (1993-1996)
Focussed on the string-finger interaction in the classical guitar. The sound of the guitar is determined by the construction of its body and the interaction which takes place between the player's finger and the string. The aim of the work was to investigate the importance of different factors affecting the interaction process, such as the frictional force between string and fingertip, the waves created on the string during the interaction and the physical properties of string and finger.
For this purpose, a three-dimensional physical model of the interaction was created. The model included transverse (in two planes) and torsional waves on the string while the fingernail and muscle of the player's finger were also modelled. The simulations predicted the movement of the string and fingertip during the interaction, the amplitude and velocity distributions of the string upon release, the force waveform on the bridge and the subsequent free string vibrations. The equations of motion were solved using the Finite Difference Method. In order to measure the string displacement during the interaction, an experimental method was devised which allowed measurements to be made at one point on the string near the plucking position.
The method used two optical sensors and detected the string shadow in two planes perpendicular to each other. Measurements were taken during real plucks from various players. Results from the computational model showed that the string-finger interaction is strongly influenced by the frictional characteristics of the fingernail, the response of the finger-muscle, the input admittance of the body and the direction of the finger movement. The interaction process was less influenced by the initial touch point between string and finger and the fingertip's speed.