## 3 Numerical Results and Discussion
### Steady-State Response Analysis
The acoustic cavity is filled with air. The point source is located at (1.13 m, 0.70 m, 0.61 m) within the conical cavity, and the point force is applied on the surface of the stiffened plate at (0.64 m, 1.41 m). Observation point 1 is within the conical cavity at (0.26 m, 1.53 m, 0.13 m), and observation point 2 is within the cylindrical cavity at (1.47 m, 0.40 m, 0.95 m). As shown in Figure 18, the sound pressure response curves obtained using the present method closely correspond to the results obtained using the finite element method. Figure 19 presents the sound pressure response of the coupling system among the composite laminated rotationally stiffened plate and the conical-cylindrical cavity under the excitation of a single monopole point source or a point force with different acoustic wall impedance values. In this coupled system, the acoustic wall surfaces have different impedance values; specifically, they are rigid: \(Z_{1}=\rho_{\rm c}c_{0}\) (\(100-j\)), and \(Z_{2}=\rho_{\rm c}c_{0}\) (\(30-j\)). The boundaries, the parameters of the geometric, the materials, and the layer angles are consistent with those in Figure 18. The point source is located in the cylindrical cavity at (0.75 m, 0.88 m, 0.45 m), and the point force is applied on the stiffened plate surface at (0.80 m, 1.05 m). Observation point 1 is situated in the conical cavity at (1.25 m, 0.45 m, 0.25 m), while observation point 2 is in the cylindrical cavity at (0.95 m, 0.50 m, 0.75 m). As shown in Figure 19, changing the acoustic wall surfaces from rigid to impedance surfaces results in a reduction in the sound pressure response amplitude, achieving a resonance suppression effect. The influence on the sound pressure response decreases as the impedance value increases. However, the change in the acoustic wall impedance in the coupled system has no effect on the shape of the sound pressure response curves. Figure 16: (**a**) Sound pressure response of observation point 1 under the point sound source. (**b**) Sound pressure response of observation point 2 under the point force. Sound pressure response curves at observation points in the coupling system among the composite laminated rotationally stiffened plate and the spherical-cylindrical cavities under the monopole point source or point force excitation. Figure 17: (**a**) Sound pressure response of observation point 1 under the point sound source. (**b**) Sound pressure response of observation point 2 under point sound source. (**c**) Sound pressure response of observation point 1 under the point force. (**d**) Sound pressure response of observation point 2 under the point force. Sound pressure response curves of the coupling system between the composite laminated rotationally stiffened plate and the spherical-cylindrical cavity at various observation points of different amplitudes of the point source or point force excitation. Figure 18: (**a**) Sound pressure response of observation point 1 under the point sound source. (**b**) Sound pressure response of observation point 2 under the point force. Sound pressure response curves of the coupling system between the composite laminated rotationally stiffened plate and the conical-cylindrical cavity at various observation points of the single monopole point source or point force excitation.