DEVELOPMENT AND USE OF A LOW-COST ACOUSTIC FLOW RESISTER METER

Acoustic Directions (AD) has developed a low-cost acoustic flow resistance meter to determine the specific airflow resistance and resistivity of fabrics, textiles and insulation. Acoustic flow resistance can be expressed in three forms: a) The airflow resistance is defined as the ratio of the pressure difference across a sample to the volume velocity of flow of air through the test sample, and is measured in mks acoustic ohms (Pa·s/m3 ). b) Specific airflow resistance is the airflow resistance divided by area of the sample (Pa·s/m) and is simply the ratio of pressure across the sample to the linear velocity of air through the sample. It is measured in Rayls. c) Airflow resistivity is the resistance divided by the thickness of the sample and is measured in mks Rayls/m. With this knowledge, information about the sound absorption properties of materials can be used to optimise acoustic design.