How to measure levels, such as in octaves and dBA

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How to use WinMLS as a level meter for measuring SPL values in octave, 1/3 octave, dBA?

If I have measured an impulse response, how can I find the level (for example in dBA)?

How to display in octaves?

How to display in dBA?

How to display several measurements (e.g. for comparison and for saving the data)?