Environment

Environment objects contain settings that affect sound propagation, such as air and ground properties.

Environment objects are also the containers for Barrier objects.

Input Parameters

Name	Data type	Unit	Comment
Library item	Lib. item	-	The library item for the environment.
Ground height	Number	m	The relative height between the ground and the top of the rail. Value must be negative, i.e. the ground is below the top of the rail.
Absorption model	Choice	-	The absorption model used in the calculations. Available options are: No ground, Rigid ground, Miki, Delany-Bazley, or Hamet-Bérengier.
Thickness	Number	m	The thickness of the ground layer.
Flow resistivity	Number	Pa.s/m2	The flow resistivity of the ground layer.
Porosity	Number	-	The porosity of the ground layer.
Tortuosity	Number	-	The tortuosity of the ground layer.
Air temperature	Number	°C	The temperature of the air.
Density	Number	kg/m3	The density of the air.
Speed of sound	Number	m/s	The speed of sound in air.
Custom graphics file	File	-	Custom background graphics can be added to the model; the file to use is specified here (with ’.xml’ file extension ).