Boundary admittance measurement method

While acoustical measurement standards have been extensively developed for absorption, diffusion, scattering, and complex impedance of acoustical materials, a standardized method for evaluating the boundary admittance in the modal frequency range of common boundary constructions remains undefined. A Working Group across ASA, ASJ, and EAA proposes anchoring the boundary admittance measurement process to the ASTM E90 Transmission Loss standard, which is already widely applied to determine STC ratings of various constructions within acoustically controlled source rooms. Experimental, theoretical, and numerical methods will be explored. As a starting point, this presentation will describe a portable in-situ impedance tube technique, and three scanning methods including, the Microflown Scan & Print, MEQ Technologies SonoCat, and a multi-layer, multi-microphone array approach. Preliminary measurements for the in-situ portable impedance tube, Scan and Print and SonoCat techniques will be presented to highlight feasibility, comparative accuracy, and future standardization potential.