| Summary: | 碩士 === 國立交通大學 === 機械工程系所 === 101 === Panel-speakers may have dips in mid frequency range on the sound pressure level (SPL) curve. In general, such dip can be harmful to the sound quality of the loudspeakers. In this thesis, the mid-frequency SPL dips are suppressed or eliminated using two different methods. In the first methods, point or distributed masses are attached to the plate at different locations to improve the smoothness of the SPL curve in a specific frequency range. An optimal design method is used to determine the locations of the masses. In the optimal design process, the vibration analysis of the sound radiation plate is accomplished using the Rayleigh-Ritz method, the sound pressure produced by the sound radiation plate is calculated using the first Rayleigh integral, and the optimal excitation location is determined using a global optimization technique. In the second method, the K-exciter is used to excite the sound radiation plate. The advantages of K-exciter are that it can be put anywhere on the plate and the shape of excitation force can be in any form. The optimal excitation locations are obtained in the optimal design. The feasibility and applications of the proposed methods have been validated by experimental results.
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