Calculation of absorption coefficient of micro-perforated absorbers

This program calculates absorption coefficient of micro-perforated panels and membranes mounted over an airtight cavity. Using the program a required absorber can be designed, and the effects of various parameters can be demonstrated. For comparison, two configurations, one with a single layer and one with double layers, can be considered. Sound incident angle can also be specified.

Basic sound absorbers include porous absorbers, single resonators, perforated panel absorbers, and panel and membrane absorbers. The perforated panel absorbers are more commonly used in practise.

• Unlike conventional perforated absorbers, micro-perforated absorber can be made from transparent materials like plastic glass.
• Unlike commonly used fibrous absorptive materials, micro-perforated absorber is fibrous-free and thus, there is no health concern.
• Micro-perforated membranes are lightweight and inexpensive.

The absorption performance of micro-perforated absorber is very good. Typically the absorption coefficient exceeds 0.4 over 3-5 octaves.

This calculation depends on the following parameter inputs:
1. Panel thickness
2. Aperture diameter
3. Aperture spacing
4. Air-space depth
5. Material (PVC or Metal)
6. Angle of sound incidence
7. Acoustic resistance of the membrane (normally 1 can be used)
8. Surface density of the membrane

For further information and algorithm, please see here.