THEORY AND DESIGN OF MICROPERFORATED PANEL SOUND-ABSORBING CONSTRUCTIONS

TLDR

Perforated panel sound‑absorbing constructions are well studied, but adjusting their acoustic resistance is difficult, limiting their usefulness; ordinary perforated panels are a special case. This paper proposes reducing perforations to sub‑millimetre size so they themselves provide sufficient acoustic resistance while maintaining low mass, thereby resolving the resistance‑adjustment problem. The authors derive acoustical properties and unified formulas for perforations of all sizes, present the theory and characteristics of microperforated panels, and provide design charts to aid practical implementation. Microperforated panels exhibit predictable absorption, simple structure, wide‑band performance, and are windproof, waterproof, heat‑ and flame‑proof when made from sheet metal, successfully solving the need for a wide‑band, high‑coefficient sound absorber in harsh environments.

Abstract

Theory and design of perforated panel sound-absorbing constructions are well developed,but the difficulties in adjusting the acoustic resistance part of such constructions curtailtheir usefulness. In this paper, a revolutionary idea is proposed that the perforations areto be reduced to submillimetre level so that they themselves will provide sufficient acousticresistance while the low acoustic mass is retained, and so the difficulty of acoustic resis-tances is resolved. Practice shows that this idea is correct. Such panels are now namedmicroperforated panels. Their features are predictable absorption characteristics, simplestructures and in addition, wide frequency bands of absorption. The elimination of porousmaterials makes the microperforated panel constructions windproof and waterproof, andalso heatproof and even flameproof for short time if they are fabricated with sheet metalor other fireproof materials. Theyefore, the problem of wide band, high coefficient soundabsorber for severe circumstances is solved for good. Acoustical properties and unifiedformulae for perforations of all sizes are derived; the theory and characteristics of themicroperforated panel constructions as well as design charts are given to facilitate the prae-tical design work. Ordinary perforated panel constructions are given as a special case.