Experimental investigation of the bulk reaction boundary condition

A local boundary condition to account for the effect of bulk reaction on the performance of sound absorbing layers was proposed by D. Bliss [J. Acoust. Soc. Am. 71, 533–545 (1982)]. The new boundary condition differs from the usual impedance boundary condition by the inclusion of an additional term involving the Laplacian of pressure taken along the surface multiplied by a complex bulk reaction coefficient, B(w). The present work shows that B(w) can be determined experimentally in a relatively straightforward manner. The experimental apparatus and the measurement procedure bear some similarity to the use of an impedance tube. The experimental results demonstrate that bulk reaction effects are important for Owens-Corning PF-705 Fiberglas board. For example, the calculated random incidence sound absorption coefficient for this material increased by an average of 39% over the range of measurement frequencies when bulk reaction was taken into account. © 1982, Acoustical Society of America. All rights reserved.

Duke Scholars

Author Donald B. Bliss Thomas Lord Department of Mechanical Engineering and Materia ...