When Visual Conservation Meets Auditory Homogenization: Multimodal Evidence from Ximen Street Historic District, Qujing, China

The conservation of historic districts is often evaluated on the basis of visible material features, yet commercialized renewal may weaken visual and auditory cues of locality while preserving building façades and street textures. We established 340 sampling points at 20 m intervals along Ximen Street Historic District in Qujing, Yunnan Province, and constructed a streetscape–audio matched sample dataset. Through multimodal model-assisted recognition, K-means clustering, XGBoost, and SHAP methods, we identified the degree of visual and auditory homogenization and analyzed the nonlinear effects and interactions of visual and auditory factors on the perception of homogenization. The results show that (1) visual homogenization presents a continuous distribution, while soundscape homogenization presents a patch-like distribution and is higher overall; (2) commercial symbolism, generic decoration, and open interfaces lead to visual substitutability, while commercial broadcasting and mechanical sounds intensify soundscape standardization; dialects, residents’ conversations, and diverse sound events enhance the perception of locality; and (3) visual commercialization and soundscape standardization have a clear interaction effect. This case study provides insights into the living conservation and renewal of historic districts in similar contexts and may offer a fine-grained analytical reference for collaborative governance that considers both visible townscape features and daily soundscape locality.