If the frequency of the incident sound wave coincides with oneof the eigenfrequencies of the underwater elastic cylinder,the corre-sponding eigenvibration will be excited by incident sound wave andstrongly reradiate sound wave towards surronding water.It has been re-vealed by previous investigations that the amplitude of backscatteringsound appears to be minimum at the eigenfrequencies of the underwatermetallic cylinders because of the destructive interference between reradiatedwave of the eigenvibration and the geometrical reflected wave from surfaceof the cylinders.In this paper,a new phenomenon has been revealed.The amplitude of backscattering sound appears to be maximum at theeigenfrequencies of a cylinder made from nonmetallic material in which thevelocity of elastic transverse wave is less than the sound velocity in water.
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