Objectives  In order to explore the feasibility of replacing steel trusses with composite reinforcements, this study proposes a composite reinforcement design for the near-field acoustic scattering characteristics of stiffened plates, and conducts the requisite experiments.

  Methods  First, based on the hydroacoustic material testing standards, a test protocol for the sound transmission performance of stiffened plates is established; second, the feasibility of the test environment and conditions is verified through the free field calibration of an anechoic pool and comparisons between the sound transmission performance of flat steel and steel trusses; finally, the sound transmission performance law of stiffened plates under the conditions of positive and oblique incidence is analyzed through experiments.

  Results  The results show that the sound transmission performance of stiffened plates under the conditions of positive and oblique incidence is basically the same, and in the order of bare plate > steel truss > composite stiffened plate. The sound transmission performance of composite stiffened plates is influenced by the cross-sectional area of the incident surface, and the smaller the cross-sectional area, the better the performance.

  Conclusions  Combined with experimental analysis to explore the future development direction of high sound transmission composite stiffened plates and ensure equal bending stiffness, the design of composite reinforcements should try to use a hollow structural form and reduce the cross-sectional area of the incident surface as far as possible; in addition, the types of material used should be minimized so as to reduce the number of different material interfaces in reinforcements.