Level (Noise) – Leq (one-third oct. bands dBA dBC etc.)

This setup is for performing a level measurement, e.g. for measuring the level of background noise.

Connect the microphone to left channel sound card input (if it is a stereo input). The sound card output will not be used.

Click help if you have not already selected the sound card settings.

Click the Next > button to continue.

To measure the correct absolute levels, the input chain must be calibrated. If you only need to compare relative levels, you may skip this part.

Calibration can be done in different ways as explained if you click help. Here we assume that you are using a microphone and have a calibrator.

Then what you need to calibrate is to click the Cal button on the standard toolbar as shown in the figure. Follow the procedure to complete the calibration.

The length of the data recorded in each measurement 2.7 seconds as default, it can be changed from Measurement→Settings… as shown in the figure.

As default, the setup is in Single measurement mode.

The plots can be updated in real time if Multi measurement mode is selected as shown in the picture. This may not work on a slow PC.

If you have an older PC, you can instead go to Measurement→Tasks… and check Automatic start of new measurement after previous.

As default, two plots are displayed. The plot to the left displays the level (Leq) in third-octave bands.

The plot to the right displays the Leq in dBA.

The levels are equivalent levels (Leq). Fast/slow etc. is planned for future versions of WinMLS.

You may add new plots, for example dBC. Do this from Window→New Window….

The third-octave plot has added a cursor and a field that displays the cursor value.

If you want to remove these tools, click in the plot to make it active. Follow instructions below.

The cursor can then be removed from Plot→Layout→Cursor.

The cursor field can be removed from Plot→Layout→Cursor Value.

On how to position or change the formatting of the cursor field, click help.

The plot to the right displays the level in dBA.

You may select another parameter, e.g. dBC or Linear and set the frequency range. To do this, go to Plot→Plot Type Settings→Level…. The dialog shown in the picture will be displayed.

From this dialog you can also divide the data to smaller parts and compute the level of each part. To do this, make sure Plot slices with length of time data window is selected.

Click help for more info.