Multisensory perception of urban courtyards: How geometry and natural elements shape enclosure and pleasantness

Urban courtyards serve as important semi-enclosed spaces that influence residents’ acoustic comfort and psychological wellbeing, yet their perceptual qualities remain under-researched compared to street canyons. This study investigates how height-to-width ratio (H/W) and natural design features (trees, vegetation, and water elements) affect perceived enclosure and pleasantness in urban courtyards through multisensory assessment. A laboratory experiment was conducted using virtual reality environments and acoustic simulations with 33 participants who evaluated courtyards varying in H/W (0.3 and 1.0), size (750 m2 and 3,000 m2), and natural features across visual-only, audio-visual, and audio-only conditions. Results showed that higher H/W consistently increased perceived enclosure while reducing pleasantness in both visual-only and audio-visual conditions. Under audio-only conditions, H/W had negligible effects on pleasantness in small courtyards, though a modest but significant effect was observed in large courtyards (η2 = 0.14). Natural features, particularly trees with birdsong, significantly enhanced pleasantness (η 2 = 0.18–0.48) and produced modest, context-dependent reductions in perceived enclosure (η 2 = 0.08–0.15 for scenario effects). Larger courtyards were perceived as more pleasant and open (less enclosed) than smaller ones in both visual-only and audio-visual conditions. Audio-visual presentation generally increased perceived enclosure (lower openness scores), while also increasing pleasantness relative to the visual-only condition. These findings offer preliminary evidence-based insights that may inform courtyard design practice, with the caveat that all participants were Japanese and stimuli reflected Western courtyard typologies; cross-cultural replication with more diverse samples is needed before broader generalisation.