Speaker
Description
Achieving high-quality building acoustic environments requires absorbers that combine frequency-tailored absorption, multifunctional performance, and compact form factors, while remaining amenable to predictive modeling and reliable characterization. Within this scope, this contribution reviews recent advances developed by the authors on micro-perforated panel absorbers (MPPAs) with parallel-arranged or coiled-up sub-cavities of different depths (PCD-MPAs). Analytical prediction models that combine MPP impedance theory with multi-cavity coupling are established for normal, oblique and random incidence conditions, and validated against finite element simulations and impedance tube measurements. Characterization is further extended to thermo-viscous regimes inside ultra-compact coiled cavities, where viscous and thermal boundary layers govern absorption peak shifts and absorption bandwidth. Beyond pure absorption, periodic sub-cavity arrangements derived from quadratic residue sequences are shown to provide simultaneous sound absorption and diffusion, validated through semi-anechoic measurements that comply with AES-4id-2001. Engineering verification is demonstrated by a PCD-MPA muffler whose sound transmission loss exceeds 20 dB across 700–1600 Hz, and by an in-situ traffic tunnel application where the mean reverberation time at 250 Hz decreases by 66% and noise attenuation at 100 m source–receiver distance improves by 17 dB. Building on these results, ongoing work on a ventilated acoustic black hole–micro-perforated panel (ABH–MPP) hybrid structure further extends broadband attenuation through coupled viscothermal dissipation and slow-wave residence effects. Together, these studies form a unified modeling, characterization and application framework that supports reversible, space-efficient design of next-generation multifunctional acoustic materials.