How Does Micro Perforated Metal Work?

Modern architecture and design is increasingly using more materials for an industrial feel such as steel, concrete and glass to meet the demands current design trends of open space facilities. These hard surfaces reflect sound and contribute to an increase in noise levels and a decrease in productive environments. Au.diMicro micro perforated timber acoustic panels counteract the noise and the unpleasant effects on staff, students and visitors.

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Au.diMicro consists of tiny micro perforations that are 0.5mm diameter to absorb noise and reduce the sound reverberation in the space, achieving an NRC value as high as 0.85, as tested by CSIRO.

Au.diMicro provides unmatched acoustic absorption while preserving the aesthetics of the timber face. The tiny perforations become invisible from a few steps away. The sound penetrates the panel through the multitude of micro perforations on the surface which acts as an Air Flow Resistance Layer to degrade reverberation. This is assisted by friction and heat loss via the tiny perforations as sound waves endeavour to penetrate the surface.

Sound is further channelled into the larger perforations located in the core of the panel where the second layer of air flow resistance – Atkar’s Sonus 2.0 integrated Acoustic Backing (SAB) – further enhances the sound absorption properties of the panel.

How does sound absorption work?

The aim of a sound absorber is to convert acoustic energy into heat energy. When the air molecules penetrate the micro perforated face, the friction between the oscillating air and the surface of the panel dissolves the acoustic energy.

Why do Architects love micro perforated panels?

The main reason micro perforated panels have become so popular among architects and designers is that they have excellent sound absorption performance but without the drawbacks of a porous material. Au.diMicro provides a surface that looks like a solid material, so can be suitable for use in certain environments as the perforations are too small for particles to enter. The solid timber aesthetics, available in a range of colours, adds to the popularity of Au.diMicro.

“Wooden micro-perforated panels (WMPP) possess excellent sound
absorption characteristics. For the demands of different projects,
selecting different structure parameters of WMPP, the
best optimization of the structure can be obtained. Because of
this WMPP structure has a good decorative effect; it is expected
to play a greater role in the architectural and the
acoustical design.”

SHENG Shengwo & MO Fangshuo, Institute of Acoustics

Additional resources:
What Are the Advantages of Aluminium Ceramic Filter Plates？

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Interested to learn more about how micro perforated panels are used as sound absorption? We’ve found these articles for you.

1.  Daa-You Maa (). “Potentials of micro perforated absorbers”. Journal of the Acoustical Society of America. 104 (5): –. Bibcode:ASAJ..104.M. doi:10./1..

2. Helmut V. Fuchs, Xueqin Zha (). “Micro Perforated Structures as Sound Absorbers – A Review and Outlook”. Acta Acustica united with Acustica. 92: 139–146.

3. Hans Bodén, Ying Guo, Hüseyin Bora Tözün (8–10 May ). “Experimental Investigation of Nonlinear Acoustic Properties for Perforates”. 12th AIAA Aero Acoustic Conference. Cambridge, Massachusetts.

A micro perforated plate (MPP) is a device used to absorb sound, reducing its intensity. It consists of a thin flat plate, made from one of several different materials, with small holes punched in it. An MPP offers an alternative to traditional sound absorbers made from porous materials.

An MPP is normally 0.5–2 mm thick. The holes typically cover 0.5 to 2% of the plate, depending on the application and the environment in which the MPP is to be mounted. Hole diameter is usually less than 1 millimeter, typically 0.05 to 0.5 mm. They are usually made using the microperforation process.

The goal of a sound absorber is to convert acoustical energy into heat. In a traditional absorber, the sound wave propagates into the absorber. Because of the proximity of the porous material, the oscillating air molecules inside the absorber lose their acoustical energy due to friction.

A MPP works in almost the same way. When the oscillating air molecules penetrate the MPP, the friction between the air in motion and the surface of the MPP dissipates the acoustical energy.

Traditional sound absorbers are porous materials such as mineral wool, glass or polyester fibres. It is not possible to use these materials in harsh environments such as engine compartments. Traditional absorbers have many drawbacks, including pollution, the risk of fire, and problems with the useful lifetime of the absorbing material.

The main reason why Micro Perforates have become so popular among acousticians is that they have a good absorption performance but without the disadvantages of a porous material. Furthermore, an MPP is also preferable from an aesthetic point of view.

For a while, perforated metal panels with holes in the 1–10 mm range have been used as a cage for sound-absorbing glass-fiber bats where large holes let the sound waves reach into the absorbent fiber. Another use has been the creation of narrowband Helmholtz absorbers which can be tuned by hole size and the dimensions of the hole distance and air gap behind the panel. However, when the hole dimensions are in the region of 0.05–0.5 mm, the narrow absorption peaks become much wider, making the additional fiber absorber more or less unnecessary, while still maintaining a very high absorption factor. By varying geometrical and material parameters, the acoustical performance can be tailored to meet a multitude of specifications in various applications.

One early contributor to the theory of micro perforated plates as sound absorbers was Professor Daa-You Maa.[1][2] Further possibilities aiming to improve the accuracy of Maa's original model are currently being investigated. One other major phenomenon that currently being investigated is the nonlinear effect i.e. an MPP behaves differently depending on the magnitude of the incident sound wave.[3]

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