Reverberation and spatial energy contrasts across three architectural typologies at the Royal Palace of Caserta

Three principal interior spaces of the Royal Palace of Caserta: a court theatre (Teatro di Corte), a royal chapel (Cappella Palatina), and a grand staircase (Scalone Reale), represent acoustically distinct architectural typologies within a single architectural complex, enabling direct acoustic comparison using a common measurement protocol. This study combines independently processed room acoustic parameters with spatial energy analysis to compare reverberation and receiver-dependent acoustic patterns across the three spaces. Measurements were conducted under unoccupied conditions following ISO 3382-1, using an omnidirectional source, an omnidirectional reference microphone and a 32-channel Eigenmike EM32 spherical microphone array. Mid-frequency mean reverberation time T ₃₀ , averaged over the 500 Hz and 1 kHz octave bands, was 2.4 s in the Teatro di Corte, 5.4 s in the Cappella Palatina and 8.2 s in the Scalone Reale, a more than threefold range within a single building reflecting the contrasting acoustic typologies of the three spaces. The Scalone Reale exhibits prolonged reverberation across all six measured positions, together with positional variation in early energy; its connected geometry provides a basis for discussing energy exchange as a possible influence on the observed decay. Relative sound energy maps derived from the spherical array show spatial patterns within selected early and later time windows at representative receiver positions, supporting interpretation of the acoustic response in relation to the surrounding architectural surfaces. The results bring the three interiors into a joint comparison of reverberation and spatial energy patterns and provide a quantitative reference for assessing the acoustic effects of future physical changes to the building fabric and use conditions of each space.