What is airflow resistivity?
Airflow resistivity indicates how absorptive a material is by evaluating how much air can pass through the material at a given volumetric flow rate. Airflow resistivity is measured according to ASTM test method C 522 “Standard Test Method for Airflow Resistance of Acoustical Materials.” Fibrous insulations have varying degrees of resistivity that are largely dependant on the density of the material. Generally speaking the higher the density, the higher the airflow resistivity, the greater the potential for sound absorption, particularly at lower frequencies. Insulations used within partition cavities require a thickness that fills the entire cavity for optimal sound control performance. The density of the insulation has a negligible effect on the STC rating of a wall1.
