Understanding how different types of vegetation structures influence soundscapes is crucial for effectively managing vegetation in urban environments, to enhance the overall quality of urban soundscapes. Despite this, relatively few studies have explored the impact that structural characteristics of vegetation have on acoustic environments and how these characteristics might influence sound perception. This study takes a pocket park located in Nanjing as a case study, using handheld LiDAR technology to collect detailed point cloud data of the vegetation in the park. These data are analyzed to calculate various three-dimensional vegetation structural parameters, which describe environmental parameters in the park. Additionally, sound recorders were employed to record the sounds of the pocket park, and these sound data were further processed to calculate key acoustic indices and to evaluate the acoustic comfort experienced by park visitors. A multiple linear regression model was developed to explore the relationship between the measured acoustic indices and the subjective evaluation of acoustic comfort. Furthermore, a random forest regression model was employed to investigate the influence of different vegetation structures on both the objective acoustic indices and the subjective acoustic comfort. We used relative importance analysis and SHAP (SHapley Additive exPlanations) analysis to better understand the relationships between the variables and their contributions to the overall soundscape quality. The findings from this study showed that: (1) the level of acoustic comfort in the park exhibited significant spatial variation, ranging from 0.45 to 6.80, highlighting the heterogeneity in the sound environment across different areas of the park; (2) key vegetation structural attributes, including the leaf area index (LAI), canopy density (D_c), trunk volume (V_t), and canopy height (H), were found to have a positive influence on both the objective acoustic environment and the subjective sense of acoustic comfort, as they contributed to noise reduction and the enhancement of natural sounds; and (3) more diverse vegetation structures were shown to improve the overall acoustic environment by reducing unwanted traffic noise and promoting the presence of natural sounds, which further enhanced the subjective sense of acoustic comfort for park visitors. This study highlights the important role that dominant vegetation structures play in determining the quality of the acoustic environment and, influencing soundscape perception in urban green spaces. These findings provide valuable insights that can assist urban planners and policymakers in making more informed decisions about how to design and manage park spaces strategically, ultimately improving park soundscapes and enhancing the public's experience of urban environments through better vegetation management and planning.