Soft Limiter Causing Distortion

I have recorded an audiobook, and am trying to get the RMS and peak levels up to spec. In order to get within the -23 to -18 range for RMS, I have tried amplifying as well as normalizing. This then brings my peaks above the required limit of -3, so I apply a soft limiter at -3db. The limiter then completely flattens my peaks, causing ugly distortion.

What am I doing wrong? Also, a friend recommended compressing instead of normalizing, but I have not figured out how to manipulate that to achieve the desired results either.

Any advice would be greatly appreciated!

What version of Audacity are you using? At some point the limiter was improved and it now uses look-ahead so it doesn’t change the wave shape.

You also need to limit after adjusting the RMS level but before exporting because otherwise the exported file will probably be clipped.

I have tried amplifying as well as normalizing.

There is a Loudness Normalization effect that allows you to exactly-set the RMS level.

Here is the [u]Recommended Audiobook Mastering Process[/u].

The posted mastering process will cause you to pass ACX RMS (loudness) and Peak almost no matter what you do without causing any sound damage. Then all you have to do is record with low background noise and you will have all three specifications.

This is the abbreviated version of the instructions from the post.

Screen Shot 2020-10-08 at 8.38.41 PM.png
Fair warning, to publish, you have to also pass theatrical testing where a real human listens to find out if you can read out loud without scaring the customer.

Also, there’s the note that home readers never pass noise. It’s hard to describe what having room noise a thousand times quieter than your voice sounds like. That’s what -60dB means—and you need to be quieter than that to pass.


There are a couple of new requirements for publishing. I have to be able to buy your book on Amazon. There is no ACX audiobook publishing without that.

Also, they published a list of bad book types. Scroll down.

We have had posters who wanted to publish cookbooks and meditation chants. I don’t think either of those made it for sale no matter how well they’re read.


We can do a quick evaluation on the forum if you read and publish a short sound test.

Read down the blue links. They’re very short and they address very common problems.