| dc.description.abstract | The tone produced by the guitar primarily depends on the vibration characteristics of its soundboard, which includes the natural frequencies and mode shapes of the guitar cavity. Through the excitation of string vibrations, these vibrations are transmitted to the bridge, subsequently driving the overall cavity vibration and resulting in sound emission from the sound hole. It can be observed from the guitar sound production process that various parameters such as string material, tension, wood species used for the soundboard, soundboard thickness, and bracing structure, have an impact on the guitar′s tone. Therefore, in this study, three main aspects are investigated the resonant frequencies of the guitar cavity, the influence of guitar strings with different tensions on the tone, and the impact of plucking positions on the tone.
The main goal of this study is to establish an objective method for defining the timbre of classical guitars. We employ a laser displacement sensor to measure the vibrations of the guitar soundboard. This approach provides a safe and non-contact measurement setup.
Through the balloon burst experiments, we obtain the spectrum of the natural frequencies of each guitar. Furthermore, we design a plucking device that integrates a tension gauge and an electronically controlled moving platform, creating a reproducible and quantitative measurement system.
Moreover, we analyze the influence of the plucking positions and string tension on timbre characteristics. The results indicate that plucking positions near the bridge generate stronger air resonances and lower ratios of string tone to air resonance intensity. Additionally, the impact of different string tensions on timbre characteristics may vary among guitars.
Since the intensity of string tone and the air resonance are the two strongest peaks in the spectrum of eh guitar, we construct a three-dimensional model of the classical guitar timbre space based on air resonance amplitude, quality factor of air resonance, and the amplitude ratio of the string tone to the air resonance . By calculating the Euclidean distance between two coordinates in the three-dimensional model, we can quantify the similarity of tones and compare the timbral differences among different guitars. The findings of this study provide a quantitative approach for investigating classical guitar timbre. | en_US |