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- Title
THE ACOUSTIC PERFORMANCE OF NOVEL NOISE BARRIER PROFILES MEASURED AT THE ROADSIDE.
- Authors
Parnell, Jeffrey; Samuels, Stephen; Tsitsos, Con
- Abstract
As part of continuing investigation into noise barrier optimisation, a research and development study to conduct insitu empirical testing of several full size prototype barrier designs was funded by the NSW State Government. Of particular interest to this study was a design known as a random edge profile barrier. Literature research had found that there was a body of evidence indicating that a barrier with an edge irregularity can cause a substantial degradation of the diffracted signal. It is generally accepted that an increase in insertion loss occurs because the jagged edge causes a reduction in coherence of the diffracted signal being transmitted to the shadow zone as compared to a conventional straight edge barrier [1-3]. It has been suggested that the mechanism for this is that the jagged geometry on the top of a barrier alters the sound pressure level in the shadow zone by causing the region of the barrier nearest the receiver to admit multiple paths with variable phase [4]. The direct waves from the diffracting edges of the barrier and waves subsequently reflected from the ground plane are superimposed at the receiver causing constructive or destructive interference at the receiver. The present study followed a methodology that included construction of an 80m long by 2.4m high barrier that served as the base for an additional conventional top as well as a random profile and T-top novel cap. Empirical data collected showed that for the receiver locations investigated, a random edge barrier will out-perform a conventional barrier of the same nominal height for most frequencies associated with broadband tyre/road noise. A T-top barrier was found to perform better than a conventional barrier of similar height for most frequencies whilst a conventional barrier offered the most practical solution for attenuation of low frequency noise.
- Subjects
NOISE barriers; NOISE control; ACOUSTICAL engineering; SOUND pressure; ROADSIDE improvement
- Publication
Acoustics Australia, 2010, Vol 38, Issue 3, p123
- ISSN
0814-6039
- Publication type
Article