Flow resistance information for acoustical design

Abstract

The measurement and use of flow resistance information for the calculation of the acoustical properties of porous materials has been examined. It is demonstrated that flow resistance information provides a description of a porous material which is sufficient to characterise its acoustical performance for all common applications. Design charts are presented which facilitate the use of flow resistance information for the three most common applications: (1) the control of the reverberant sound field in an enclosure, (2) the improvement of the transmission loss through pipe wrappings and enclosure walls and (3) the attenuation of sound propagating in ducts. Measured values of flow resistance for fibrous and foamed products available in Australia are presented. Information is also presented for estimating the flow resistance of fibrous products of generally uniform fibre diameter. Alternatively, a means for the measurement of flow resistance is described.