Sound Insulation

Sound reduction index R measurement

The Sound reduction index R defines the laboratory insulation capacity of a compartment.

The calculation is carried out by comparing the source and receiving room average sound spectra (after considering background noise effects).

The receiving room equivalent absorption area can be used as calculation correction factor.

Procedure

Perform the reverberation time measurements

Perform the average reverberation time and the equivalent absorption area calculation

Perform the measurements of single average spectra in average mode

Download the measurement data files into a PC folder.

Click on the Start Analysis button (or select the menu item Analyze -> SOUND INSULATION -> Start).

In the window that opens, select the Sound reduction index measurement and click OK to confirm.

You should create a new project containing all files concerning the processing or open an existing one.

Create the project "R_index".

The input data window will open.

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Pressing the Open File upper button, opens the data files (dl5 extension) concerning the measurements of:

• source spectrum and source room background noise spectrum (source room - spectra with switched-on source box)

• source room background noise spectrum (source room - background noise box)

• source spectrum and receiving room background noise spectrum (receiving room - spectra with switched-on source box)

• receiving room background noise spectrum (receiving room - background noise box)

Once opened, each file appears in the application main page, as in the following example:

Open the example file in the CDRom "Noise Studio - Sample files" (D:\Esempi\IsolamentoAcustico\R_index\spettri tottava, and add the sections

• 1-3 for the source room with switched-on source

• 2-4 for the source room with background noise

• 5-7 for the receiving room with switched-on source

• 6-8 for the receiving room with background noise

To add the just opened file's data, press <ADD>

Repeat the same steps for all measurements.

To remove an already added file, select it using the mouse and press <REMOVE>

Then you need to add the correction factor due to the Equivalent absorption area. Press Insert in the Equivalent absorption area section, the following window will open. Here, you can enter the equivalent absorption area from file, or manually input the values in the table.

Select the item "From File..." and choose the file in the CDRom "Noise Studio - Sample files" (D:\Esempi\IsolamentoAcustico\R_index\Area Assorbimento Equivalente.eaa

Enter the tested separation element surface area in the appropriate box. To proceed with the coefficient calculation, press Calculate R

The application shows the sound reduction index R trend, as well as the source and receiving room signal average spectrum either as a table or graphically. The equivalent absorption area is only shown in the form of a table.

Furthermore, the measurement environmental parameters (separation element surface) and the global evaluation index Rw are supplied.

Now, from the menu item "File -> Save as..." you can save the result.

The result is saved in this example file in the CDRom "Noise Studio - Sample files" (D:\Esempi\IsolamentoAcustico\R_index\Riduzione sonora.Rif

Pressing the Details key, the same index as a function of frequency is shown,

and a comparison table of the just calculated index and the law requirements for different types of unit environments.