SMALL change needed to low RMS

Submitting my first book to ACX. I have 11 chapters where the RMS is too low, but BARELY. My largest change is needing to raise the RMS by 1.3db, and the smallest change is .1

Is there a quick, easy way to do this? It’s such a small change that I don’t think I need to worry about clipping. I’m guessing this problem happened when they were converted to mp3s…

Thanks in advance.

The [u]Recommended Audiobook Mastering Procedure[/u] will get your RMS & peaks levels into spec every time.

I looked at that and did the suggested settings and I still get the same error message. Any other suggestions, please??

I still get the same error message.

From where? There are four possibilities: The actual submission process goes through an automated quality control step, you can submit to ACX AudioLab—which we assume duplicates the submission acceptance process, you can use Audacity ACX-Check, and you can use the long arduous Audacity manual process that ACX-Check replaces.

We expect all of those to produce results within small fractions of each other.

Audacity Audiobook Mastering is designed to guarantee the two physical volume checks, Peak and RMS. You must use all three tools, in order, without messing with the settings. It’s not mix and match. It’s a suite. A harmonious grouping.

Yes, the conversion to MP3 does affect the volume and that slight volume change is built into the tools.

So Something Is Wrong.

Do you still have your studio set up?

Record and post this ten second voice test.


I get the warning from ACX. I have 48 chapters recorded, only 11 of them have issues, all under 1 DB of an issue (with RMS being too low). I paid a sound person to do the settings for me, and they should be within levels of ACX requirements. Like I said, most of the chapters are. Only a few aren’t. I have all the “settings” that are supposed to be there, and have already done the ACX check and it just tells me the same thing. Which sections are too low. However, I dont’ know how to FIX it. I am completely new to audacity and am going on the settings of my sound guy. His recommendations are the same on ACX website as well as this website.

Is there a simple way to raise everything by 1DB?

Is there a simple way to raise everything by 1DB?

The [u]Amplify Effect[/u].

That will also boost your peaks by 1dB (and the noise floor too). If your peaks go out-of-spec you’ll have to run the limiter again. As you know the RMS requirement has a rather wide 5dB range (-18 to -23) so if it’s too low you can raise it more than 1dB, you just have to watch (or re-limit) the peaks.

Select the chapter. Effect > Amplify. Set the top number to just larger than the error and ignore everything else. > OK.

See if they accept that. If peaks fail, run Effect > Limiter at these settings.

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I know we seem to be dancing around this, but you may be the one person on the planet where the normal audiobook mastering tools failed. It would be super good to find out why.

What did your production company say when you told them about this?