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Sound Reduction Spectra

Spectra of the sound reduction index (transmission loss) are managed via the libraries Sound Reduction Indices (menu Tables|Libraries (local) and (global)) are managed sound spectra. The library can be extended by the user.

Note

The data on the sound reduction index provided in the global library are listed in the VDI guideline 2571 2714-88.

When referencing to a spectrum of the sound reduction index from the global library in a project, CadnaA will generate a copy of this spectrum in the local library Sound Reduction Indices. The reference to a spectrum is established by its ID which is, therefore, mandatory to enter.

Furthermore, spectra from the global library can be copied to the local library by clicking the button „--> Local Lib.“.

Accessing Sound Reduction Spectra

In the dialog of point, line and area sources, sound reduction spectra are accessed by activating the option „TransLoss“ and clicking the file selector symbol in the line „TransLoss“ (see Common Input Data).

dialogue Point Source: The file selector symbol is outlined in red, clicking the symbol gives access to sound reduction spectra (local or global), selectable after activation of option „TransLoss“

The following modifications are available:

  • clicking the file selector symbol in the line „TransLoss“ gives access to the local library Sound Reduction Indices or
  • holding the SHIFT key pressed while clicking the file selector symbol in the line „TransLoss“ gives access to the global library Sound Reduction Indices.

Export/Print of Sound Reduction Spectra

The sound reduction spectra from the libraries can - like any other table - by copied to the clipboard by clicking the button "Copy" or be printed or exported (see Text Files (.txt, .rtf)) by using keywords (see Table in the manual "Attributes, Variables, and Keywords"). Printing and exporting using this keyword occurs just for the local library:

#(Table, LibR)

Entering new sound reduction spectra

New sound reduction spectra can be entered in two ways:

  • starting from the object dialog of point, line and area sources by clicking the file selector symbol in line „TransLoss“ (with or without holding down the SHIFT key) and entering the new spectrum in the particular library, or

  • via the menu Tables|Libraries (local) or (global)|Sound Reduction Indices.

Note

In order to enter several sound reduction spectra it is recommended to enter the spectra via the Tables menu and to assign the spectra to each of the respective sources afterwards.

Regarding the general handling of object tables and the input of new data records via the context menu, see Object Tables.

Spectra - as with other kinds of library objects - can be edited directly in the respective table or - after a double click in a table row - be entered on the dialog Spectrum.

Dialog Spectrum

ID

It is mandatory to enter an ID for each spectrum. Please consider the respective rules for the ID (see Dialog Options Name, ID, INFO, ObjectTree, Master in the manual „Introduction to CadnaA“). In particular with library objects, a character is mandatory as the ID‘s first character.

Name

description of the spectrum

Source

description of the data's origin

Pocket Calculator Symbol

Via this symbol the present spectrum can be modified (see Modify Spectrum).

Rw (C; Ctr)

displays the weighted sound reduction index and the spectrum adaptation terms C and Ctr according to ISO 717-1 717-1996 of the spectrum entered.

Option „1/3 Octave Band Spectrum“

after activation a third-octave spectrum can be entered

Button „Convert“

see Spectra, Conversion of Spectra

Octave or Third-Octave Bands

Enter the sound reduction index (transmission loss) in the each octave or third-octave band here. Consider that a levels 0 dB does not mean "no input". Therefore, when having no data in an octave band available, enter a space or keep the input box empty. in this case, this band will be considered as not valid.

Note

When a value in an octave or third-octave band is missing for a source, the resulting level after calculation is not shown on the dialog Receiver for the respective frequency band.

Arrow Buttons <-|->

to move to the next/previous dataset

Button "New"

generates a new table row below the row currently selected