From ornamentation to acoustics: A quantitative analysis of Tong Bori elements in Persian architectural heritage

This study presents archaeoacoustic research in Iran, examining the acoustic functionality of Tong Bori, a sophisticated ornamental plaster technique in historical Iranian architecture, with a particular focus on Isfahan's 17th-century Ali Qapu Palace Music Hall. Through an innovative methodological framework combining historical analysis with quantitative acoustic experimentation, this research challenges traditional interpretations of Persian architectural ornamentation as purely decorative elements. The study employs advanced acoustic measurement techniques adapted to work within cultural heritage preservation constraints, analyzing how geometric configurations of Tong Bori elements influence acoustic parameters in enclosed spaces. Experimental results demonstrate that spaces incorporating these vessel-shaped niches exhibit significant acoustic improvements, including enhanced amplitude modulation, controlled reverberation, and superior sound diffusion compared to conventional surfaces. The research methodology involved constructing scale models with various ceiling configurations inspired by the Music Hall's Cut-Out Muqarnas and carved plasterwork. This enabled quantitative analysis of acoustic performance while respecting preservation protocols that prohibited direct site testing. Findings reveal intricate acoustic engineering in Safavid-era architecture, suggesting intentional acoustic design through the strategic implementation of geometric patterns and material layering. This research addresses a critical gap in archaeoacoustical studies of Iranian architecture while establishing methodological precedents for investigating historical acoustic spaces under preservation constraints. The study's significance extends beyond archaeological documentation, offering valuable insights into heritage conservation and contemporary acoustic design while demonstrating the technological sophistication of historical Persian builders.