By introducing the acoustic-structure coupling between Guqin resonator and the air in the cavity in the simulation process of modal analysis, the corresponding displacement field modes and acoustic field modes at different frequencies are given. The influences of the air inside the cavity on the vibration of resonator as well as the influence of the vibration of resonator on sound pressure in the cavity are investigated by comparing the simulation results of coupled system with structural system and acoustic system. Results suggest that breathing modes have larger contribution to Guqin’s volume, and the radiating volume from the breathing modes has different forms when the faceplate and baseplate vibrate in different phases. The relationship between the frequencies of exciting forces and the volume of Guqin was built by theoretical deduction. This provides a reference for luthiers who can adjust Guqin’s volume by changing the frequencies of exciting forces.
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