Sonic Characteristics of the Landscape - Soundscape Ecology: Principles, Patterns, Methods and Applications - page 29

Chapter 2
Sonic Characteristics of the Landscape

2.1 Introduction

Knowledge of the sonic characters of the landscape is important to evaluate the
modalities of propagation of polluting noise, to manage noise abatement actions, to
investigate and better understand animal communication for conservation purposes,
and to assure sustainable development and a standard of well-being for humans.
Physical and biological patterns across a landscape are the principal drivers of
the sonic environment and related dynamics. Topography, weather, and vegetation
are, at a local scale, the most important factors of sonic characterization. We have to
add to these characters other geographic components (e.g., flatness, steepness) and
anthropic components (e.g., houses, infrastructures).
In the urban landscape, obstructions such as walls, houses, bushes, and highway
barriers have refractive properties on sounds. However, the effect on sound propa-
gation is minimal for buildings and similar structures because the obstruction to air
flow is sufficient to raise the viscous and thermal boundary layer to the vicinity of
the superior part of the buildings; for instance, paved roads reduce ground absorp-
tion more than occurs in natural flat lands.

2.2 Weather Conditions and Sound Propagation

The effect of weather on sound propagation is not only an important physical issue
but has many connections with vegetation structure and animal communication
modalities.
Meteorological effects may be severe for signal transmission, but this largely
depends on the type of landscape and on climatic variability (Albert 2004 ).
Investigation of this aspect is quite old and has fascinated generations of
physicists (Ingard 1953 ). Sound is attenuated more by wind gustiness than by
humidity, fog and rain, temperature, and wind refraction. Ground attenuation is