Audiobook RMS

Audacity 2.3.3
Mac OS 10.15.3

I have very limited knowledge on the technical side of this but my boss has recorded an audiobook that we’re trying to submit and I’m falling at the final hurdle, this is the issue they’ve told us we need to fix -

Requirement: files measuring between -23dB and -18dB RMS

Solution: Please raise the overall RMS level of each file to within our requirement. For example, if a file’s RMS is -30dB RMS, it must be raised +8dB to be within our -18dB to -23dB RMS requirement range.

I’ve found out how to find the overall RMS of the track (or what I think I have) I’ve selected the whole track and gone to Analyse - Contrast and it tells me that the first track I’m working on is -37.69.

In very simple terms would someone be able to help me on what steps I need to take to get this track to what it needs to be for submission? I’ve read through some other forum posts and they get quite technical!

Thanks in advance for all your help.

Requirement: files measuring between -23dB and -18dB RMS

That’s step one in chasing your own tail. You fix the RMS (Loudness) and that throws the Peaks off and then you fix that, etc, etc.

We publish a three-step process that guarantees Peak and RMS and if you recorded well in a quiet, echo-free room that may be all you need.

Do you still have the original recordings? The recordings before you did anything to them? That’s best. Make sure you have copies of them as safety backups that you never touch except to copy into work files.

There are published mastering processes (other than ours) that use some tools that permanently distort the voice and those are rough to recover from.

That’s an excerpt from the official instructions here.

The tools were chosen to have minimal effect on voice quality and in general, if they’re not needed, they don’t do anything. They are a suite, a harmonious grouping and must all be applied and in order.

The second instruction block gives guidance how to get the two tools you have to install, the two tools that aren’t included in a factory-fresh Audacity.

ACX Check is super handy because it has all the audiobook measuring tools in one go as well as a pass/fail announcement. No more Effect > Contrast.

Once you use the tools the first time, the settings stick and whipping through all the steps can be done in about twenty seconds.

If you fail Noise, the third ACX specification, then it can get a lot more entertaining.

Let us know how it goes.


You represent the worst-case situation. You’re not the reader. Do you know the game “telephone?” You whisper a message to one person and they whisper it to another, through a pile of people. You see what comes out the other end.

It’s possible we may need your reader to produce a short sound test according to a set formula. It’s not unusual for readers to miss the formula. You will be going through an additional layer. Is that going to set off fireworks? Is the studio and microphone still set up?


This is a great help, thank you for this information.

I’ve tried following the steps and I don’t have RMS normalise so I’ve found a link to download it, a .ny file? But have no idea how to get it to work through audacity, tried other steps suggested on other forums and just can’t figure it out, am I missing something here?

Thanks again

Use this plug-in that’s part of Audacity: Nyquist Plugin Installer - Audacity Manual

RMS Normalize will be shipping as part of Audacity for the next release (hopefully next week) - it is now enabled though by default.