Study on Effects of String Tension on Inharmonicity and Acoustic Characteristics in Classical Guitars

It is generally perceived that higher string tension tends to result in a sound that is perceived as clearer. Therefore, the purpose of this paper is to examine the characteristics of the sound produced when the tension of classical guitar strings is varied, based on 3 indicators: inharmonicity, overtone composition, and volume. Spectral analysis using a Fast Fourier Transform (FFT) analyzer and a comparison of sound volume using an oscilloscope were conducted. The results confirmed that increasing string tension reduces inharmonicity, thereby quantitatively demonstrating the phenomenon given by the theoretical equation. Furthermore, as string tension increased, dissonant interval content rate decreased, while the volume increased. Based on the above results, it is considered that the perceived clarity of tone when string tension is increased is attributable not only to a reduction in inharmonicity but also to a decrease overtone in the dissonant interval domain. Furthermore, an increase in volume was observed, it is suggesting that increasing string tension brings about desirable acoustic characteristics from the perspective of many factors, including clarity and volume. By applying these findings to the selection of strings with higher tension, the development of strings using materials with higher linear density, and the development of guitars with new structures that achieve equivalent higher string tension, it is considered that this paper can contribute to improving the acoustic characteristics of classical guitars.