| dc.description.abstract | This study aims to investigate the resonance coupling phenomenon between classical guitar strings and the structure of the soundbox. It is understood that not only does the occurrence of beat tones happen when the vibration frequency of the guitar′s soundboard matches that of the strings, but also strong coupling and beat tones are formed when the frequencies of the strings and the air piston vibration are close or identical. Through both numerical simulations and experimental approaches, we seek to understand the impact of string frequency sweeping through the guitar′s air resonance frequencies on the instrument′s tone quality.
Initially, mathematical simulations involve coupling models of a two degree of freedom system of the guitar, simulating the mass of the soundboard and the air piston in the soundhole, which is then extended to the coupling between the guitar strings and the air in the soundhole. In practical experiments, laser rangefinders and a sound pulse excitation device, both of which are non-contact measurement and excitation tools, are employed to obtain the air resonance frequencies and soundboard mode frequency responses of Classical Guitars A and B. Subsequently, a combination of a tension gauge and an electrically driven moving platform is used to achieve quantitative plucking of the guitar strings. Experimental results will be discussed regarding the quality factor, coupling factor, amplitude, and spectral energy of string and air resonance frequencies.
Ultimately, the results indicate that selecting appropriate plucking techniques, playing styles, and strings based on specific conditions can mitigate the influence of beat tones on the tone quality of the guitar during performance.
Keywords: wolf tone, two degree of freedom system, classical guitar, laser displacement sensor, non-contact excitation, coupling factor. | en_US |