This study numerically investigates the acoustic response of a seven-bladed propeller under the axisymmetric turbulent boundary layer at the stern of the SUBOFF bare hull model, aiming to clarify the noise generation mechanism with focus on the effect of propeller suction on vortex structures. The Reynolds number based on hull length is 1.3*10^7, and two advance ratios (0.85 and 0.55) are adopted. Large-eddy simulation is used to resolve the boundary layer, and the FW-H equation computes the far-field sound. On the basis of previous studies, this work further analyzes how propeller suction stretching upstream vortex structures affects noise. Results show that the haystacking and blue-shift phenomena originate from successive cutting of the same upstream turbulent structures by adjacent blades. Driven by propeller suction, structures in the tail-cone boundary layer develop rapidly into slender vortex filaments and are prone to repeated cutting. This stretching-cutting coupling is closely related to rotational speed: as the advance ratio decreases, the turbulent length scale shifts from single cutting to successive cutting. Numerical results well capture the influence of advance ratio on the acoustic field and are verified by open-water simulations.