A Scale Model Study of Parallel Urban Canyons

Abstract

Shielded urban areas are of importance regarding urban citizens' annoyance and adverse health effects related to road traffic noise. This work extends the existing knowledge of sound propagation to such areas by a scale model study, rather than by model calculations. The scale model study was executed for two parallel urban canyons at a 1 to 40 scale, with a point source located in one canyon. Cases with acoustically hard façades and absorption and diffusion façade treatments were investigated. To correct for excess air attenuation of the measurements, a waveletbased method has been applied. The measurement results in the shielded canyon show that, in contrast to the directly exposed street canyon, the levels and the decay times are quite constant over the length of the canyon. The energy-time curve in the shielded canyon is characterized by a rise time, which can be related to the sound pressure level. The rise times and decays can be explained by separate reflection, diffraction and diffusion processes. A closed courtyard situation enlarges the level difference between acoustically hard façades and applied façade absorption or diffusion treatments at both the directly exposed and shielded side. A comparison between measurements with two different diffusion mechanisms, horizontal and vertical diffusion, reveals that vertical diffusion yields lower levels at the shielded side compared to horizontal diffusion for the investigated situations.

Using natural means to reduce surface transport noise during propagation outdoors

“…Consequently, this concept has become part of the noise policy in a number of European cities [114]. Therefore, potentially quiet areas, like urban courtyards, have been studied in detail [115][116][117][118][119][120][121][122]. Although courtyards are often strongly shielded from direct exposure to road traffic noise, many of such places were found to exhibit noise levels that are too high to function as quiet areas [123].…”

Meteorological influence on sound propagation between adjacent city canyons: A real-life experiment

“…This typical behavior in a non-directly exposed canyon was found as well based on the detailed scale modeling of adjacent city canyons described in Ref. 17. Time-domain simulations in Ref.…”

Analysis of Residential Façade Patterns from Acoustic Viewpoint

“…Like in room acoustics, in the aim to reduce noise level within street, the effective strategy based on correcting the acoustic properties of urban spaces can be used. Few studies suggested using absorption and diffusion devices as a façade treatment to reduce noise propagation, like absorbent patches on the façades, and on the ground [17] [18] or oriented ones on the façades [19].…”