Acoustic Survey for the Characterization of a Medieval Cave Church

Vibroacoustic monitoring provides a measurement-based approach for investigating heritage spaces in which architectural morphology, environmental conditions and sound-related practices are physically interrelated. This study applies a portable and non-invasive monitoring protocol to the medieval cave sanctuary of San Michele di Mezzo, located in Fisciano, Southern Italy. The site consists of stratified natural and built spaces, including a lower cave, an upper cave and a later upper church, and rep-resents a relevant case study for assessing the acoustic behaviour of small, irregular and fragile cultural heritage environments. The experimental procedure combined calibrated microphone recordings, time-domain signal inspection, third-octave-band analysis and impulse-response-derived room-acoustic indicators, including reverbera-tion, clarity and definition parameters. The results show that the lower and upper caves are acoustically differentiated, with the lower cave displaying more favourable clarity and definition values in selected low–mid frequency bands relevant to vocal practices. At higher frequencies, the differences become less systematic, indicating that the acoustic distinction between the two spaces is frequency-dependent rather than absolute. Comparative data from other cave and cave-like environments further con-textualize the measured response of San Michele di Mezzo. The findings do not imply intentional acoustic design; rather, they show that the long-lasting devotional central-ity of the lower cave is compatible with measurable acoustic conditions supporting spoken or sung ritual practices. More broadly, the study contributes to applied vi-broacoustics by demonstrating that low-invasive field monitoring can provide repro-ducible acoustic indicators for heritage interpretation, conservation-oriented docu-mentation and the investigation of intangible sound-related dimensions of cultural heritage.