Attenuation characteristics of tones and vibrations in guitars with nylon, fluorocarbon, and phosphor bronze strings pressed down against fret

抄録

We report on the effects of internal losses in strings on the attenuation characteristics of tones and vibrations in guitars with nylon, fluorocarbon, and phosphor bronze strings. Radiated sounds and vibrations of bridges generated by individually plucking the 1st, 2nd, 3rd strings pressed down against the 1st or 13th fret were studied. Attenuation coefficients of sound and vibration acceleration from the 1st frequency mode to the 10th frequency mode were determined on the basis of time variations of sound pressure and vibration acceleration levels. Storage and loss elastic moduli and elastic loss factors of nylon, fluorocarbon, and phosphor bronze strings were measured using a dynamic mechanical analyzer. The motion equation, which includes the complex elastic modulus, provided the mode frequency relating the inharmonicity and attenuation coefficient depending on the loss elastic modulus. Nylon and fluorocarbon strings demonstrated further increases in attenuation coefficient when they were pressed down against the 13th fret. The motion equation suggests that the results are caused by the loss elastic modulus of the string material. Attenuation coefficients of fluorocarbon strings were smaller than those of nylon strings because of their higher tension and density and smaller diameter, even though their loss elastic moduli were the same.