Acoustic Pots in Ancient and Medieval Buildings: Literary Analysis of Ancient Texts and Comparison with Recent Observations in French Churches

During the last decade, acoustic pots inserted into the walls and roofs of medieval and modern churches have been the focus of renewed scientific curiosity after a long time of relative silence. Traditionally, authors from the Middle Ages to the present time considered that Vitruvius established the relation between the “vasa aerea” (bronze vessels) in ancient Greek theatres and the “fictilibus doliis” (earthen vessels). Vitruvius's text and philosophy is analysed with regards to acoustics, and his recommendations are compared with medieval, modern and contemporary texts about acoustic pots. Most of them hints at an acoustical purpose for the pots. Therefore, the literature survey is supplemented with an acoustical survey of 25 French churches where pots still remain. Recent measurements and observations in some those churches, completed with recent data from foreign studies, are consistent with an acoustical purpose of the pots to decrease the reverberation time at frequencies strongly excited by the spoken voice.