Acoustic Performance of Glazed and Unglazed Hexagonal-Flower Ceramic Tiles in Small Enclosures: A Frequency-Dependent Reverberation Time Analysis

This study evaluates the frequency‑dependent reverberation time and equivalent absorption characteristics of glazed and unglazed three-dimensional (3D) hexagonal-flower-patterned ceramic wall tiles in a small room enclosure across six octave bands (125–4000 Hz). Using a controlled measurement methodology compliant with ISO 3382‑2 standards, 56 independent reverberation time measurements were conducted for each surface treatment, and the resulting RT60 values were converted into band‑specific equivalent absorption areas (Sabins) and absorption coefficients of the tiled wall, providing room‑volume‑independent descriptors of acoustic performance. Results demonstrate that the glazed ceramic 3D relief surface yields a mean RT60 of 1.62 s (averaged across all frequencies), representing a 14% reduction compared to the unglazed variant (1.96 s) and a measurable increase in equivalent absorption area, especially around 500 Hz, where the relief geometry is most effective. Notably, the glazed surface exhibits greater frequency stability in the speech‑critical mid- to high-frequency range (500-4000 Hz: RT ≈ 0.95-1.22 s), whereas the unglazed surface shows considerable variability, with a pronounced resonant peak at 2000 Hz (2.29 s) that severely degrades speech-relevant acoustic performance. Both materials demonstrate elevated reverberation times at 125 Hz (>3.85 s) and modest equivalent absorption, indicating limited low-frequency absorption capability due to their small thickness and rigid mounting. The hexagonal-flower 3D surface geometry contributes to diffusion effects that moderate specular reflections at higher frequencies, making the glazed variant suitable as a complementary acoustic treatment and decorative three-dimensional wall cladding. However, integration with broadband absorbers (porous or resonant systems) remains necessary to achieve target reverberation times for residential and office applications. This work provides quantitative acoustic performance data for 3D architectural ceramic wall tiles expressed both as RT60 and equivalent absorption units and establishes a methodological framework for evaluating decorative diffusive building materials within the acoustic design context.