A comparison of two procedures for in-situ measurements of sound absorption coefficient

The Adrienne method is an often used measurement technique developed for outdoor (in-situ) measurements of sound reflection and airborne sound insulation. It is standardized in the CEN/TS 1793-5 norm[1]. This norm was used as a base for the design of a measuring system for determining the absorption coefficient and sound insulation of noise barriers, ceilings and other wall systems. The goal of this paper is to compare the Adrienne method for in-situ measurement of the absorption coefficient and another method which is very similar to the first mentioned method, except it uses multiplication of the impulse responses with the ratio between estimated time of arrival of the direct and reflected incoming sound impulse, as used in some commercial acoustic measurement applications such as Easera.