ACX RMS level

if you could explain that low rollof

Sorry. Missed a step.

Low Rolloff for Speech is a standard, built-in Equalizer preset in Audacity 2.1.3. This is an excerpt from the instructions.

Select the work to be corrected or a whole performance by clicking just above MUTE at the left of the timeline.
Effect > Equalization > Select Curve: Low rolloff for speech, Length of Filter: about 5000 > OK.

This is the whole document.

Using the filter is two sentences. Explaining what you’re doing and why is the rest of the page.

Koz