An archaeoacoustic study on Cappadocia; acoustical identification of religious and secular indoor spaces

The goal of this study is to identify the indoor sound fields of Cappadocian special rock-cut structures and by this to provide the platform of discussion on the aural effects in the original use and context of spaces. Cappadocia’s rock-cut structures have been enlisted as mixed -natural and cultural- World Heritage Sites by UNESCO. The spaces of Cappadocia from the Middle Byzantine Era have been studied from an archaeological perspective; however, this study is the first of its type as it investigates such spaces from an auditory perspective. Similar acoustical studies have been conducted on natural caves (Paleolithic caves) and man-made structures (Neolithic structures, Roman catacombs) from around the world. The methodology of this study is composed of three steps; in-situ field tests of five rock-cut structures (one church and four residential halls) from Middle Byzantine sites of Hallaç, Açıksaray and Avanos, impedance tube tests on rock samples from Göreme and Ürgüp for estimating their sound absorption coefficients, and virtual reconstruction of Çanlı Kilise by ray-tracing simulations. According to tube measurements and room acoustics simulations, the Cappadocian tuff from different parts of the region is found to have different sound absorption properties and thus, various physical properties. Acoustic parameters (EDT, T20, T30, C80, D50, and STI) are obtained for the spaces under study by field tests and room acoustic simulations. Based on acoustic analysis from field measurements and simulations, both the church spaces are suitable for liturgical practices. On the other hand, the residential halls are found to favor speech-related activities more. The acoustics of rock-cut spaces are also compared with natural caves and man-made structures from other parts of the world; when the acoustic parameter results are compared, the Cappadocian tuff is found to be more sound absorptive than the karst in natural caves but less absorptive than the tuff in Roman catacombs.