Fraisse, Tarlao and Guastavino move soundscape research from diagnosis to intervention. Four temporary sound installations were deployed across two summers in the same public space and evaluated through 825 questionnaires, allowing the authors to compare how distinct compositions altered calmness, pleasantness, perceived loudness, restorativeness and attention to existing sound sources. The central proposition is that sound can be designed as an urban resource rather than addressed only through noise mitigation. Each installation produced common improvements while also generating composition-specific effects: abstract sounds tended to become more noticeable, whereas nature sounds supported stronger restorative responses. Crucially, the installations redirected attention away from other non-dominant sources, revealing acoustic design as an operation on perceptual hierarchy. The study bridges sound art, landscape architecture and evidence-based urban design by treating artistic intervention as experimentally assessable. Its wider significance lies in demonstrating that aesthetic practices can function as low-cost, site-specific urban instruments whose effects are measurable without stripping them of compositional specificity.