Box source

Box sources are used for sound sources that can be approximated by a 3-dimensional box, with different sound powers radiated from each face.


Each Vehicle can contain any number of Box source objects, which include properties for their location, geometry and sound power.

Each of the Box sources are assigned a Box source library item, and in this way many Box sources can be reused across your project. Box sources can be added or deleted, by right-clicking on the appropriate items in the model objects view . The order of the Box sources in the model objects view is determined by their distance from the front of the Vehicle.

Input Parameters

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Name Data type Unit Comment
Label Text - A label for this Box source. This will be used to identify the Box source in the calculation and results. Special characters are not allowed.
Enabled Checkbox - Specifies whether this source is enabled in the calculation. This is a convenient method to deactivate a single source without removing it from the model. Note that for a source to be active in the calculations, its source grouping conditions must also be met.
Centre distance from vehicle front Number m The distance between the front of the Vehicle and the centre of the Box source.
Centre height above rail Number m The vertical distance between the top of the rail and the centre of the Box source.
Centre distance from track centre Number m The horizontal distance between the centre of the Track and the centre of the Box source. Positive values are towards the left from the perspective of a forward travelling train.
Source grouping Lib. item - The Source group that this Box source belongs to.
Library item Lib. item - The library item for the Box source.
Box source length Number m The length of the Box source (in the track longitudinal direction).
Box source width Number m The width of the Box source (in the track lateral direction).
Box source height Number m The height of the Box source (in the vertical direction).
Sound power input file File - The file location for the Box source sound power is specified here (with ’.txt’ file extension ).
Use narrowband auralisation Checkbox - Select to use a narrowband file for auralisation. This will take the narrowband data and shape it to fit the output 13 octave band results, applying Doppler shifts as necessary, and maintaining any tonal content.
Narrowband file File - If the option to use narrowband data for the auralisation was selected, this is the file to be used for the narrowband spectrum (with ’.txt’ file extension ).
Sound power mode Choice - Select whether the specified sound power is to be considered as ‘constant’ or ‘speed dependent’.
Input file speed Number km/h If the sound power has been selected as being ‘speed dependent’, this is the reference speed used for the specified sound power level.
Speed coefficient Number - If the sound power has been selected as being ‘speed dependent’, this is the speed coeefficient that will be used to apply a correction for the speed. For example, setting this to 30.0 will apply a 30.0 log10(v/v0) correction (where v and v0 are the train speed and reference input file speeds, respectively).
Insertion gain - - Here, manual corrections can be specified to increase or decrease the sound power level data used in the calculations. Clicking on the button will launch a dialog window to input this data as either a single value for all frequencies, or as a pasted spectrum of corrections (comma separated over the range 20-20,000 Hz). Corrections can also be adjusted for individual frequency bands.

In the calculations, each Box source is split into six area sources, representing each side of the box. Each of these area sources is split into several sub-sources, each with a half-monopole directivity, facing outward from the box. No noise is radiated to their reverse sides.

.When specifying the sound power levels of each side in the text file, six lines of data are required in the following order:
1. Right
2. Top
3. Left
4. Bottom
5. Front
6. Back