LIN Jianheng1,2 YI Xuejuan2 YIN Baoyou1,2  GUO Shengming1

(1 Key Laboratory of Underwater Acoustic Environment, Chinese Academy of Sciences  Beijing 100190)

(2 Qingdao Lab, Institute of Acoustics, Chinese Academy of Sciences  Qingdao  266023)

Received Aug. 15, 2008

Revised Sept. 17, 2008

Abstract The perturbation characteristic of ambient sea noise field caused by scattering of submerges objects are discussed theoretically. Based on the sea noise source model with Gaussian-correlation amplitude, and applying the integral expressions for arbitrary source distribution and the spherical wave expression of Green function for a monopole in half-infinite space, the expressions of direct-arrival noise fields, scattering fields, scattering fields and total noise fields of a rigid spherical object under the irradiation of monopole and dipole sources, as well as the covariance among those noise fields at two receiving points are obtained. The numerical results of scattering directional patterns of rigid spherical objects and the visibility are given. It is shown that the total noise field is affected by not only the impedance characteristics of the object, the direction of receiver, but also the correlation between surface sources, and the interference between direct-arrival and scattering fields greatly. The results show that the sound visibility of a rigid spherical object is about 4-5 dB in near range and the scattering directivity characteristics of a rigid spherical object under the irradiation of surface sources are different from those of plane wave incidence. 　　　

PACS numbers: 43.30, 43.60