Effect of the open roof on low frequency acoustic propagation in
street canyons
Applied Acoustics, (2010)Abstract
This paper presents an experimental, numerical and analytical study
of the open roof effect on acoustic propagation along a 3D urban
canyon. The experimental study is led by means of a street scale
model. The numerical results are performed with a 2D-Finite Difference
in Time Domain approach adapted to take into account the acoustic
radiation losses due to the street open roof. An analytical model,
based on the modal decomposition of the pressure field in the street
width mixed with a 2D image sources model including the reflection
by the open roof, is also presented. Results are given for several
frequencies in the low frequency domain. The comparison of these
approaches shows a quite good agreement until f = 100 Hz at full
scale. For higher frequency, experimental results show that the leakage,
due to the street open roof, is not anymore uniformly distributed
on all modes of the street. The notion of leaky modes must be introduced
to model the acoustic propagation in a street canyon.