Scale-model study of the effectiveness of highway noise barriers
| Autor: | Murray Hodgson, Clair Wakefield, Todd Busch |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Sound Spectrography
Acoustics and Ultrasonics Berm Point source Microphone business.industry Acoustics Models Theoretical Line source Motor Vehicles Soil Optics Arts and Humanities (miscellaneous) Noise Transportation Roadway noise Noise control Humans Polystyrenes Insertion loss business Scale model Geology |
| Zdroj: | The Journal of the Acoustical Society of America. 114:1947-1954 |
| ISSN: | 0001-4966 |
| DOI: | 10.1121/1.1605412 |
| Popis: | A scale-model facility was developed to test the insertion loss (IL) of highway noise barriers. Three model materials were utilized to simulate packed-earth berms and ground (expanded polystyrene), vertical walls (dense polystyrene), and roadways (varnished particleboard). Thirty-eight noise-barrier configurations were tested and used to compare how IL varied with changes to the barrier profile for walls, berms, and combinations of walls and berms for receivers at a representative, highway-adjacent location. The atmospheric conditions were assumed to be homogeneous and nonrefracting. Changes of barrier surface impedance were also assessed. A highway line source was simulated by positioning both an air-jet point source and a receiver microphone at a series of equally spaced points, in order to form an array of source-receiver measurement pairs making differing angles of propagation to the noise-barrier crest line. The IL measurement results are presented in unweighted third-octave bands. In addition, total A-weighted insertion losses (ILA) were obtained by applying an A-weighted, traffic-noise spectrum. When a berm was modeled with surface impedance closely matching that of packed earth, it was found that walls outperformed berms by 1 to 2 dBA. When the surface impedance of a berm was modeled to be acoustically soft, the ILA increased sufficiently to favor berms by about 2 dBA. The result for an acoustically soft berm does not support the long-standing practice of assuming that earth berms outperform walls by 3 dBA, but is consistent with the performance predicted by newer prediction algorithms. When the slopes of berms were made shallower, the IL generally decreased for a berm alone, but generally increased in cases with a wall atop the berm. |
| Databáze: | OpenAIRE |
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