Cs. You et Sw. Yoon, PREDICTIONS OF TRAFFIC NOISE-PROPAGATION OVER A CURVED ROAD HAVING ANIMPEDANCE DISCONTINUITY WITH REFRACTING ATMOSPHERES, Journal of the Korean Physical Society, 29(2), 1996, pp. 176-181
The polar parabolic equation (polar PE) method, which introduces bound
ary fitting coordinates into the wide-angle parabolic equation (PE) me
thod, was used to solve sound propagation over a curved surface and ov
er irregular terrain. The polar PE and PE methods, which march the fie
ld with matrix elements in range, can include sound propagation having
range-dependent ground-surface and sound-speed profiles. The matrices
should be updated at the discontinuous point to allow range-dependent
sound propagation. The polar PE calculations were obtained for sound
propagation over a curved surface, radius of curvature 200 m, having a
homogeneous ground surface and a discontinuous ground surface. Those
ground surfaces represent an all-asphalt road, asphalt to grass-covere
d ground, and all-grass-covered ground. The discontinuous ground surfa
ce, asphalt to grass ground, started 30 m from the acoustic source ove
r an asphalt road. Calculations with no refracting atmosphere show tha
t lawn-covered ground near the road reduces the traffic noise level to
about 10 dB for 200 Hz and to about 20 dB for 300 Hz at a distance 20
0 m away from the source along the curved surface.