Abstract
Experimental data have shown that the noise barrier’s performance can be improved by introducing jaggedness into the top edge of the barrier. In the present work a combined experimental/numerical investigation was performed. The numerical investigation employs the Directive Line Source Model [Menounou et al., J. Acoust. Soc. Am. 107, 103–111 (2000)] and reveals the basic global characteristics of a jagged profile that increases the shielding effect over a straight edge barrier having the same average height. For a jagged edge profile consisting of finite-length segments inclined with respect to a straight top edge it was found that its performance depends on the inclination angle of the finite-length segments with respect to the horizontal, the directivity of the diffracted field, and the length of the inclined segments with respect to the spatial duration of the incident sound signal. It was also found that jagged profiles offering an increased shielding effect for certain receiver locations are different from jagged profiles offering moderate improvement over many receiver locations. The numerical predictions were verified experimentally. Experiments were carried out in air using a spark source generating N-shaped pulses, a capacitor microphone and a rigid aluminum plate with various jagged top edge profiles. [Work supported by Texas ATP.]