On the Design of Perforated Facings for Acoustic Materials

An approximate analysis of the acoustic behavior of perforated facings for absorptive materials is outlined and is reduced to a design chart. Only the mass reactances of the holes and of the facing material are included in the analysis. This simplified picture is adequate for many practical problems, but breaks down for certain conditions which are discussed. If the acoustic impedance of the unfaced material is known, absorption coefficients for the material with perforated facing can be read directly from the chart.