Source Spectrum

The spectrum and overall level of a sound source are edited on this page. A source is composed of 1 or more pieces of equipment. A maximum of 4 different types of equipment may be combined, and there may be any number of each type of equipment. To select equipment, press the Add Equipment buttons. This will bring up the page Equipment.

Levels may be directly edited if desired. Click on the appropriate cells and enter the levels. Note that it is not possible to directly enter an overall level, only levels of individual frequency components can be entered, and the overall level is summed from these contributions.

Increasing the entry in the Count column multiplies the given row by that factor, this is used for multiple collocated sound sources of the same type.

The Duty column specifies the percentage of time that the given equipment is active during the assessment time period.

The box Level type allows different level types to be selected: SL, SWL (Lw), and SEL. Note that changing the level type will also scale the currently entered level values, so it is recommended to choose the level type before entering source level data.

The Crest factor (dB) is a way to incorporate impulsiveness information into the source. The Crest factor indicates the dB-level above the RMS-level of the highest peak in the signal. It is applied when assessing peak levels (Preferences Sound level display), and is applied to all frequency bands. If you are interested in finding peak values please consider doing a time series solve instead, as it uses the actual signal and not derived information.

Mitigation

It is possible to add mitigation (attenuation, such as bubble curtains) to this source, by clicking on the button Add mitigation. Mitigation may be entered as a constant value across all frequencies, or by choosing mitigation spectra from the library. Positive mitigation values indicate reductions in emitted sound power level.

Image 1: Mitigation window.

Copy to clipboard

The contents of the table may be copied to the clipboard with the button Copy to clipboard.

Image 2: Edit source spectrum window.