Acoustics of snare drums : an experimental study of the modes of vibration, mode coupling, and sound radiation patterns
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The basic acoustical characteristics of snare drums, such as the modes of vibration, the interaction between different drum parts, and the sound radiation patterns of low-frequency drum modes are investigated in this work. Two different snare drums were used in the experiments. One was a Ludwig drum with a metal shell. The other was a Remo drum with a shell of a composite material. First of all, tensions of the drum heads were measured using the deflection method. Then, the vibrational modes of the drum heads, the drum shell, and the complete drum were carefully measured in experiments using both mode-scanning and modal analysis techniques. Drum head coupling was observed for the 01 and 11 drum head modes. It was found that the interactions between the two drum heads are mainly caused by acoustical coupling through the air enclosure rather than by mechanical coupling through the drum shell. A two-mass/three-spring model was constructed to describe the coupling behavior in the 01 mode. Experimental results support the correctness of the model. Finally, sound radiation patterns of different drum modes were measured in an anechoic chamber. Monopole, dipole and quadrupole patterns were observed in radiation from the 0 1 and 11 coupled drum modes.