How to plot spectrum in octave or one-third-octave bands?

The easiest way is to load the setup named Level (Noise)_Leq (dBA, dBC, etc., third-oct bands) from Setup->Load…. Below it is described in more detail how it can be done without loading the setup. This is not intended to be used for transfer function measurements, since it will give a 3 dB/octave bias because of the integration explained below.

The energy or power of a signal can be plotted in octave or one-third-octave bands if Frequency response/Spectrum is selected as the plot type. In Plot->Plot Type Settings->General Frequency Domain... select the scope mode to one of the settings below.

What you choose depends on if the signal you are analyzing is stationary or transient. If you set it to Automatic which is recommended, WinMLS automatically determines the setting based on the measurement parameters.

Go to Plot->Plot Type Settings->Active Plot… to display the plot settings dialog box. Make sure that the setting below is selected.

Click the OK button to exit the dialog boxes.

An example of 1/3 octave normalized energy is displayed in the figure below.

For information about how to change curve styles, see the How to change the curve style section.