How to Optimize the Acoustic Performance of Perforated GRC Panels?

As a material that combines decorative and acoustic functions, perforated GRC panels require a systematic design process to optimize their acoustic performance (mainly sound absorption and sound insulation), involving "perforation rate, rear structure, cavity depth, and filling materials." In projects such as theaters, lecture halls, and transportation hubs, Qinglong Group combines the shaping capabilities of GRC with acoustic design. Through scientific parameter adjustment, the sound absorption coefficient of perforated GRC assemblies in the mid-to-high frequency range can reach above 0.6 while maintaining good decorative effects.

Core Principle: Combining Resonance Sound Absorption with Porous Material Absorption

A perforated GRC panel is itself a resonance sound absorber. When the frequency of a sound wave matches the natural frequency of the resonance system composed of the perforated panel and the cavity, sound energy is dissipated through the friction and resonance of air in the hole necks. Optimizing acoustic performance means adjusting system parameters to align the resonance frequency with the noise frequency bands that need to be absorbed (such as the main frequency bands of human voice).

Key Parameter 1: Perforation Rate (Hole Diameter and Spacing)

Perforation rate is the primary factor affecting resonance frequency and absorption bandwidth. The higher the perforation rate, the more the resonance frequency shifts toward high frequencies, and the wider the absorption bandwidth usually is. Qinglong's design experience shows that for broadband sound absorption, the perforation rate is generally between 10% and 25%. Hole diameter (typically 3-10mm) affects high-frequency sound absorption, with smaller diameters favoring high-frequency absorption. Hole shapes can be round, square, or specially shaped decorative holes. Using parametric design tools, we can precisely control the perforation rate required for acoustics while satisfying pattern aesthetics.

Key Parameter 2: Rear Cavity Structure and Filling

This is key to improving the sound absorption coefficient and broadening the absorption frequency band. 1) Cavity depth: Increasing the thickness of the air layer behind the panel can lower the resonance frequency, which is beneficial for absorbing low-frequency noise. The depth is typically 50-300mm. 2) Filling with sound-absorbing materials: Filling the cavity with porous sound-absorbing materials (such as centrifugal glass wool or rock wool) can transform pure resonance absorption into efficient broadband absorption. The sound-absorbing material should be placed tightly against the back of the panel. 3) Cavity sealing: The back of the cavity should be a rigid reflective surface (such as a concrete wall), and the cavity perimeter should be sealed to form an effective resonance chamber.

Optimizing Sound Insulation Performance

Perforated panels themselves have poor sound insulation performance. If sound insulation requirements must also be met, a double-layer or multi-layer structure of "perforated GRC panel + cavity + sealed backing panel" must be adopted. In this case, the perforated GRC mainly serves decorative and sound-absorbing functions, the sealed backing panel (such as gypsum board or cement board) bears the main sound insulation function, and the middle cavity and sound-absorbing wool further improve the overall sound insulation. Qinglong can provide integrated acoustic decorative system solutions that combine structure, acoustics, and aesthetics into one.