Proxy churches as tools for historical virtual acoustic reconstruction: The 12th-century acoustics of Notre-Dame de Paris

Accurately reconstructing the acoustics of lost historical spaces requires interdisciplinary approaches and careful consideration of uncertainty. This study presents the development of an acoustical model of a Romanesque cathedral, termed Notre-Dame II, that was replaced in the 12th century by the current cathedral in Paris. This was done to examine the acoustic conditions under which early Parisian polyphonic music may have been performed. Notre-Dame II, described in surviving documentation and found in ruins underneath the modern cathedral, required reconstruction through indirect evidence due to the absence of detailed architectural plans or descriptions. A proxy church of similar era and construction was selected to approximate key geometrical and material parameters. Material properties were estimated based on comparable historical structures, and the calibration relied on known acoustic metrics in the proxy, including reverberation time and clarity. Uncertainty arose at multiple stages, including limited documentation of Notre-Dame II, assumptions about proxy church materials, and the inherent limitations of computational acoustics methods. This study highlights how iterative calibration and sensitivity analyses mitigate these challenges, providing insights into the use of extant structures to study the acoustic experience of lost buildings.