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Chapter 2 - Sound Sources

General Sources

Sound sources, the emission of which is described based on the sound power level are called "general sources". In CadnaA, the emission of general sources (such as point, line, and area sources) can be described by single number ratings (sound power level PWL in dB(A)) or by spectra (linear, or with A-, B-, C- or D-weighting) and for the three time periods Day/Evening/Night separately. When both emission types are present within a project, both are included in the calculation at the same time. Within a spectral calculation the sound pressure level or any other evaluation parameter (see Evaluation Parameters Tab) at the receiver point is calculated as a spectrum (linear or A-, B-, C- or D-weighted) and as a sum level in dB(A).

Spectra are entered in the local or global libraries (see Spectra), and are referred to in the edit dialog of the source by entering their ID (see manual „Introduction to CadnaA“).

Parametric Sources

The emission parameter of „parametric sources“ is not the sound power level, but several source type specific parameters. For example, the following sources are parametric sources:

Those source types require to specify an emission parameter which is specific to the standard/guideline or, for example the overall traffic count, the percentage of heavy vehicles, the type of road surface, and the traffic speed where the emission parameter is calculated from.

The input figures can be specified for the three time periods Day/Evening/Night even when the selected standard just provides only one or two time periods.

The input of objects is explained in the manual „Introduction to CadnaA“.