Adio book rejected - need help!

I have spent a great deal of time recording an audiobook on Audacity but it has been rejected by Audible

The big issues are:

Issue: The following files do not meet our noise floor requirement (high pitched mechanical noise) – All Submitted Files
Requirement: a maximum -60dB noise floor
Solution: In post-production, you may use noise gating or reduction to help reduce the noise floor.

Can anyone advise me on how to use ‘noise gating or reduction’

Issue: 19 files have a low RMS and are too quiet: Please see attached document for a graph of affected files.
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 can not see anywhere on Audacity where you raise the db RMS - can anyone point me to where you do this?

Any help hugely appreciated!


How did you record the work? Describe the microphone. Part numbers?

Were you following someone’s recommendations for performing?

Have you ever installed custom tools or software into Audacity? We do publish audiobook mastering and analysis tools, but they need to be installed. The don’t come with regular Audacity.

Do you still have your studio set up? Can you record a 20 second sound test?

This will give us first-person edivence of what’s happening.


I have been given some encouraging news by the technician at ACX

He is now saying that the problem with noise floor is only in one chapter so re-recording that chapter is relatively easy

He is also saying the following:

In regards to the RMS issue - you simply need to raise the level of your files by 5 or 6 dB’s to bring them in to our required level of -18 to -24dB

Be sure to keep a limiter set at -3dB to avoid peaking issues

I am sorry to be so unversed in all this but could someone show me where on the Audacity dashboard are the levers/buttons for changing the dB level? I have searched and searched! If I can get this sorted I think I am away!

Best wishes


We have RMS Normalize, but it’s not included with Audacity. You have to download and install it.

After you use that, Effect > Limiter will suppress peaks that exceed -3dB.

Both of those tools are included in the ACX Audiobook Mastering process.

As part of that process, we include ACX Check which will tell you if your chapter passes ACX without having to actually submit the work to them.

That’s why I asked if you ever installed an Audacity tool or software before.