Industrial Noise Calculations

This module consists of many parts of different areas of SoundPLAN. The Geo-Database contains the information where the sources geometry (shape and location) is described. The Library hosts most of the acoustically relevant data. The Calculation core is responsible for calculating the noise levels and delivering the feed data for the Documentation, for the Expert System for Industry Noise, and for various Graphics modules.

The source description for industrial noise is always the sound power over frequency. Additions can be defined for non-spherical spreading, directivity, tonality and impulse type noise. If the source is not constant over the time period, a time histogram provides the needed adjustments.

As all sources are described in terms of the sound power, the sources description allows the calculation to be carried out with any of the standards implemented in SoundPLAN.

Sources can be point, line and area sources. Line and area sources can be defined with the total sound power or with a sound power per meter (or square meter) of the source. To insert a new source, select the source type and click on the drawing to place the source. After the first coordinate is entered, SoundPLAN will open the source definition window. Under the General tab, define the sources name, make any necessary comments, and select the time history of the source from the library. In the box titled "Calculation mode," the source can be set to be a center frequency calculation or to use spectra for the sound power. Center frequencies are assigned on the spot; spectra are handled via the library.

Spectral information is prepared in the library so the spectra can be made available for all projects. Data can be imported from a general ASCII interface which can be configured to import Excel data.

The spectra can also be associated with a directivity. In general, the directivity of a source is an horizontal directivity. However, some special cases demand more flexibility. For smokestacks, the directivity is a vertical, rotational symmetrical directivity. Loudspeakers for large public address systems can be simulated with a 3D directivity which is valid for all frequencies, or can be declared for each of the frequency bands.

When sources are not radiating full spherically, the remaining "open" direction must be increased in strength by 3 dB for half spherical, 6 dB for quarter spherical....If a source is close to a wall, SoundPLAN directly attaches the source to the wall and establishes the spherical adjustment. In the calculation, SoundPLAN ensures that the reflection at the facade where the source is attached is disabled.

In many cases, the source for the environmental calculation is a building with its facades and roof. The environmental noise from a factory building is determined by the noise inside the building and the noise transmission through the walls. The SoundPLAN industrial noise model simulates the noise inside or uses typical values of several industries from a library. The walls are then defined in their transmission index and the program calculates how many dB the wall will radiate into the environment. To insert windows and doors with a different transmission index, simply navigate to the facade (the little window in the middle shows you where you are) and pull open a box with the dimensions of the new window. If the window is not correctly positioned, you can manually edit the coordinates. The calculation core automatically breaks down the facade into triangles and only calculates the sections with its corrected sound power. There is no need to work with difference spectra or to later subtract the wall emissions from the window part.

The Industrial Noise model is directly linked to the Indoor Factory Noise calculations. For details, please see Calc. Indoor.
It also creates feed data for the Documentation and for the Expert System for Industrial Noise. Please see these pages for details.
It is also used to prepare data for all Graphics modules.

Last modification: 15 January  2004

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