Speech intelligibility challenges in contemporary worship spaces in Croatia

The transformation of church architecture over the past century, characterized by extensive use of concrete, glass, and stone, has introduced significant acoustic challenges in these worship spaces. This paper investigates the speech intelligibility problems in 19 contemporary churches across Croatia, focusing on the impact of modern construction materials and architectural designs. The prevalent use of large, plain reflecting surfaces, combined with minimal sound-diffusing and sound-absorbing materials, has resulted in excessive reverberation times that hinder clear communication. The problem is further compounded by typical loudspeaker placement patterns, where loudspeakers are often mounted at considerable distances from the congregation. Our analysis presents comparative acoustic measurements including reverberation time (RT), critical radius variations based on different loudspeaker configurations, and a newly developed church oversize factor that quantifies the acoustic challenges resulting from these combined conditions. The results demonstrate that the measured RT values significantly exceed recommended ranges for good speech intelligibility, while the critical radius measurements reveal substantial limitations in the effective coverage area of installed sound systems. These findings provide valuable insights for architects and acoustic designers working on modern church projects, suggesting the need for revised approaches to contemporary church acoustics.