SOUND PROPAGATION IN URBAN SPACES
Basic acoustical imaging theory is examined for its utility in assessing sound propagation in urban areas. Imaging theory assuming smooth-wall, specular reflection is determined not to be appropriate for urban propagation simulation, because building surface irregularities modify the sound field in a city street relative to a smooth-wall channel. To account partially for surface irregularities, a first order model of scattered reflection is developed. This model incorporates the added absorption effect produced by scattering from irregularities into the acoustical imaging theory. The propagation model is shown to be valid only when there is direct line of sight between source and receiver. In order to develop a more widely applicable urban noise propagation model, the scattered field produced by typical building surface irregularities is examined in detail with acoustical model studies. A second order model of scattered reflection is developed from these results. The applicability of this scattering model and a further modified form of specular imaging theory to general urban sound propagation is verified with field and acoustical model data. Using the second order scattering model and imaging theory, computed attenuation values are presented for a number of typical urban geometries. The computed values are applicable to point and line sources and to traffic flows. Additional factors affecting urban sound propagation are discussed. (TRRL)
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Corporate Authors:
Massachusetts Institute of Technology
Department of Civil Engineering, 77 Massachusetts Avenue
Cambridge, MA United States 02139 -
Authors:
- Donovan, P R
- Publication Date: 1976
Media Info
- Features: References;
- Pagination: 266 p.
Subject/Index Terms
- TRT Terms: Digital computers; Errors; Forecasting; Image processing; Mathematical models; Sound; Theses; Traffic; Urban areas
- ITRD Terms: 8673: Digital computer; 6440: Error; 132: Forecast; 8633: Image processing; 6473: Mathematical model; 6748: Sound; 8597: Thesis; 755: Traffic; 313: Urban area
- Subject Areas: Highways; Operations and Traffic Management;
Filing Info
- Accession Number: 00480160
- Record Type: Publication
- Source Agency: Transport Research Laboratory
- Files: ITRD, TRIS
- Created Date: Mar 31 1989 12:00AM