There are many applications where glass is used extensively, such as atria, lobbies, offices, museums, board rooms, etc. Excessive reverberation and interfering reflections are often the result. However, traditional sound absorptive materials applied over these surfaces would defeat the initial intent to provide outdoor views and natural lighting. Now a new acoustical technology is available to address these acoustical needs, while maintaining the transparent design intent. Clearsorber™ Sheet is based on new patented technology, utilizing microperforations in a transparent or translucent sheet. When the Clearsorber™ Sheet is spaced off vision glass, these microperforations produce significant viscous losses, providing the necessary sound absorption. Applications are only limited by the imagination. The Future Is Clear!

The Clearsorber Sheet is a 1 mm or 1.5 mm microperforated PETG or PETA transparent sheet with 0.5 mm diameter holes spaced 5 mm x 5 mm apart. The 1 mm sheet weighs 0.26 psf and the 1.5 mm sheet is 0.375 psf. The maximum size is 2500 mm (98.4”) x 1250 mm ( 49.2”)

Problem
Projects designed with extensive use of glass surfaces can produce strong interfering reflections and excessive reverberation, which create an uncomfortably loud ambiance, causing fatigue, and corrupting speech intelligibility.

Solution
To address these acoustical problems, while maintaining natural lighting and visibility, RPG introduces Clearsorber™ Sheet, made from microperforated polycarbonate. If the perforations in a Helmholtz resonator are made sub-millimeter in diameter, they are comparable to the thickness of a boundary layer of air. As sound passes through these microperforations, sound absorption will occur due to viscous boundary layer effects in the perforations, as long as an air cavity is provided between the Clearsorber™ Sheet and the vision glass. It is then possible to achieve sound absorption without the need for additional porous material in the cavity behind the microperforated sheet, thus allowing the panel to be transparent or translucent. Therefore, the Clearsorber™ Sheet offers an acoustical solution when a clear sound absorber is required.

Absorption
Sound absorption is provided by viscous losses in the microperforations, whose sub-millimeter diameter is comparable to the thickness of a boundary layer of air. As sound passes through these microperforations, sound absorption will occur due to viscous boundary layer effects in the perforations, as long as an air cavity is provided between the foil and the vision glass boundary. It is therefore possible to achieve sound absorption without the need for additional porous material in the cavity behind the microperforated sheet, thus allowing the panel to be transparent or translucent. Resonance occurs where the imaginary part of the surface impedance crosses zero. The viscous term increases the mass in the microperforations and hence shifts the resonant absorption to mid-low frequencies. The real, resistive part of the impedance is optimized to provide maximum sound absorption.

Installation Clearsorber™ Sheets can be mounted or suspended with exposed decorative metal hardware (examples shown to the right) or formed into a panel spaced off a non-perforated sheet with acrylic borders to provide both sound absorption and sound isolation.

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Light Transmitting Microperforated Sound Absorbing Sheets From the Industry’s Leading Innovator