How to set RMS on recorded chapters

Hello dear forum - I have recorded all the chapters of my book, using latest Audacity, etc. When I check RMS level (peak level and noise floor is fine) I get a message saying decibels are -24.5 instead of -23.5. My question is - how do I reset the RMS on recorded files? Thank you so much. Be safe.

You can use RMS Normalize. It has to be installed.


Are you planning on submitting to ACX/Audible? Did you post a test to see if everything was OK before you read the whole book? Or is that message from ACX?

Audacity has an Audiobook Mastering suite of tools that guarantee Peak and RMS and if you read well in a quiet, echo-free room, Noise should fall in and that’s all you need.

I need to change machines.


Before you start any surgery, do you have backup copies of your raw readings and edit masters? That’s highly recommended given how far into the process you are. Either save Audacity Lossless Projects, or Export WAV (Microsoft) 16-bit sound files. Copy them to separate storage such as external drives, thumb drives, or cloud storage.

It’s totally possible to fix one technical standard and mess up the others.

We produced the Audiobook Mastering Suite.

Screen Shot 2020-02-15 at 4.16.02.png
That’s from here.

Always apply all three tools to every chapter or section. ACX Check is very similar to the ACX automated robot. It will tell you if all three of your technical standards have been met, and by how much.

Of course in the case of ACX, you also have to pass Human Quality Control which listens for reading errors and sound quality.

As a fuzzy rule, you should clear Noise by at least -65dB, not just -60dB which is the actual standard.

Did everything come out OK?


Thank you and sorry for the delay in responding - what a ride this recording project has been!

Yes, these tools helped enormously, but I still didn’t pass ACX QA - (extraneous sounds and incorrect spacing at beginning and end of clips) I have created a better space to record in and have figured out how to use room tone in the editing process so fingers crossed for my next pass with them.

Still curious about the noise reduction tool - if I follow the sequence audacity created for Audible, I shouldn’t need to use it, right? BTW this process (filter, rms normalize, limiter) is quite elegant and worked every time to pass the ACX check.

Thank you again,

this process (filter, rms normalize, limiter) is quite elegant and worked every time to pass the ACX check.

Close. Audiobook Mastering guarantees Peak and RMS (Loudness). You can put floor sweepings in there and pass those two. But you may not pass noise. Noise is very troublesome. Anyone who has struggled with background noise now knows why commercial soundproof studios exist.

I have a very quiet bedroom and can push out a technically perfect voice performance any time I want…as long as I miss the Metrobus going by and the trash collection people on Monday. I recently published a file of what it sounds like when Southern California Gas decides to put a new gas trunk line under the street.

(incorrect spacing at beginning and end of clips)

I am a little surprised people regularly get stuck with that. ACX is pretty clear they want.

extraneous sounds

No refrigerators turning on or dogs barking. Those are Noise.

I have created a better space to record in

How did you do it? There’s tricks to it. Yes, it’s totally possible to use egg cartons inside a large cardboard box as your sound studio, but you have to use cardboard egg cartons, not plastic foam.

I published a kitchen table sound studio from furniture moving blankets and plastic pipes, which, if you’re close to a Home Depot, come pre-cut.

Still curious about the noise reduction tool

Noise Reduction used to be called Noise Removal. Too many people were expecting it to remove all the noise from their trashy performance…to zero. Neither one will do that.

Noise Reduction is a siren song luring your ship on to the rocks (Greek mythology). There’s the philosophic problem of starting your career planning for disaster rescue. You should think about possible sound damage, but not intentionally taking shortcuts because you can always “fix it in post production.”

Kiss of death.

If you can pass noise by -65dB or quieter naturally, you can ignore Noise Reduction. -60dB is the limit.

That’s assuming nice, well-behaved, stable, constant noise such as microphone hiss or far background air conditioning noise. It won’t do anything for noises that change over time (trucks going by) or certain digital noises that sound like ice picks in the ear. Those will not be tolerated even if they are quieter than -65dB.

So it’s down to seeing how you do. You can also publish a very short sound test here and we will comment. You don’t need the Catskill cows if you have a good speech you like. Do Not use “testing one two three.” A passage from Sponge Bob Square Pants might be nice.


If your ACX-Check looks like this.

Then you have the old one. There is a new, faster version with a shorter response panel. If you’re using Audacity 2.4.1, the older version may stop working.


thank you so much ! Here’s a clip that passed ACX - I have a very quiet space (I live in a rural area, no traffic) and now I have have blanketed corner of my closet - I hit the correct noise floor with ACX. What I’ve found is that the other tools - filter - rms normalize - limiter seem to work better with noise reduction in play - but perhaps that’s wrong -

how do I upload a clip?

I use RMS normalize, downloaded the plug in - should I download Audacity 2.4.1 please? would that be a good idea or not necessary? thank you so much for your help…
SiddharthasampleBEST.aup (5.39 KB)

OK, here is a clip in the format you requested. Thank you for your time and expertise.


Extra points if you can read that all in one breath. [gasp] Catskill Farms…

I got the file to pass Audiobook standards, but it took a little effort to get there. It should sound exactly like you except very slightly louder and passing audiobook standards.

First I used the Audiobook Mastering Suite as published.

You still have a little house power hum in the show and I used a Hum Remover tool to get rid of it. You’re in the US, right? It’s US kind of hum.

That left you passing technical standards—but just barely. So I added a very gentle noise reduction

This is the newer ACX Check.

This is the mastered file. Peaks are quieter than -3dB, RMS (loudness) is between -18dB and -23dB, and noise is quieter than -60dB.

These are the settings for Hum Removal.

And these are Noise Removal settings

It’s 6, 6, 6, so I call it Noise Reduction of the Beast.

Do you remember turning your head as you were reading at about the 6 second mark? There is a noticeable drop in volume right there. You can’t do that while reading for a bunch of different reasons. It sounds a little funny (like you lost your place) and it’s very difficult to fix. You can add processing tools to help, but they can throw the other tools and corrections off. You start chasing your tail.

We can try to find out where that hum is coming from or we can just go with the hum removal tool. My personal preference is to use a few tools as possible. You only have to fix the hum noise once, but you have to remember to remove it, every time, in every file, forever.

Let us know which direction you want to go and I’ll fill in the blanks. I’m going to go look at your other sound file.


There are no obvious voice distortions caused by echoes or other wall, ceiling reflections. So your studio seems to work. Can you breathe in there? That’s the only significant problem with closet studios. Oh, there is one more. There’s a famous story of an audiobook performer who locked herself into a hotel closet by accident—with the microphone running.

You are reading on the cusp of multiple different tools, versions, releases and services. I would probably stay where you are. Where are you? Which version are you using? Which Mac?

If you get a system to work DO NOT Upgrade, Update, or Improve anything. If you have auto update selected, turn it off temporarily. There are a number of people on the forum who got stuck with the last Mac update which temporarily killed Audacity and some of its tools. Then there was an Audacity version that had troubles managing sound files. The current Audacity, 2.4.1 is a little brittle and is scheduled to be replaced soon.

Once you get something working, freeze the machine until you start a new book.

More later.



AUP isn’t a sound file. It’s a list of instructions to tell Audacity how to put your show together from all that stuff in the _DATA folder. That’s where the actual sound is—in little pieces.

This is one complete Audacity Project.

They have to be together in the same location or folder, they can’t be one inside the other, you can’t rename them, and it has to be the name you gave them inside Audacity.

If you want to submit a show sound file to the forum, you can’t go much over about 20 seconds of mono (one blue wave). Drag select what you want and export it the same way you did the voice test.


Wow, this is so cool! Thank you! Hum removal is in the current Audacity or do you recommend upgrading to the latest version? Yes, I’m in the US and of course that means we have both weird hums in our houses and want the latest and greatest - just kidding. I live on a mountain and it’s extremely quiet but I do have a refrigerator a room over (the house is a big barn like structure) I’ve spend the whole day adding fabric material to the corners of the closet where I record, yet sounds like the hum is still there…

I will review the returned sound file (those happy cows) you’ve sent back, and download version 2.4.4, next.


OK, yes, just got this - will abort the update. Yes, I can breathe in the closet but it’s getting dicier as I add fabric - now I’m a little nervous! :smiley:

I live on a ridge in Big Sur, California, have been here 20+ years. This is the latest in my gig economy endeavors due to high risk factors during this pandemic - don’t want to go back to my front-line tourism job. I have been working on submitting my own book to Audible, Romancing the Sur, available on Amazon in print and ebook form at this point. Very happy with it - a well received rendering of what it’s like to live “on the edge” if not in a closet!

Thank you again, sorry to be a bit frazzled.

Let’s see you’re still using the slightly older mastering, so you will still be using RMS Normalize (later Audacity versions have a built-in one called Loudness Normalization).

This is the hum remover I’m using.

de-hum.ny (2.11 KB)
It shows up in Audacity as “Hum Remover.” I posted the settings.

Noise Reduction is in two passes. Drag-select some typical noise. Effect > Noise Reduction > Profile.
Then select the whole chapter and Effect> Noise Reduction at the settings I posted > OK.

Analyze > ACX Check. Either one works. The longer one has more information, but you only need those three readings.

Which Audacity and which Mac?


sorry to be a bit frazzled.

It’s a bit more complicated than buy a microphone, plunk it down on the kitchen table and whip out an audiobook, no matter what the ads say.

My joke is to read books, make a fortune and retire to a tasteful villa on Côte d’Azur. You may have loused up the joke. Hard to beat Big Sur. Rustic Cabin? Is it rustic? How rustic is it?


It is so rustic it needs a new roof! Fortunately this is on the eaves, not yet above the closet. :smiley: This winter it’s time for a new tarp.

But it is a breathtaking spot - feeds the soul. It’s actually been lovelier here than ever, so quiet.

Thank you again for your help! I just installed the de-hum plug-in and will follow your instructions.

Have a great weekend out there (where are you?)


OH my! That worked great! :stuck_out_tongue:

The system has two goals. It has to pass the ACX specifications for technical quality and it has to sound exactly like you. The ACX philosophy is that it has to sound like someone telling you a fascinating story over cups of tea.

That last part may seem obvious, but many people find an insane urge to spruce up a bad recording by applying effects, corrections, and filters so the technical specifications are met, but the voice sounds like a bad cellphone. No, they won’t like that at ACX any more than you would like listening to—or paying for—a story in cellphone voice.

There is one production trick that helps “even out” the volumes and theatrical projections. Listen to yourself on headphones. After you get used to it, it’s amazing how that keeps your volume levels stable over a long read. The instant you start to wander off for any reason, your headphone voice drops and you snap yourself back to good volume. That’s one reason almost all theatrical reads have the performer on headphones.

That’s Chris Pratt voicing Emmet in The Lego Movie.

The only technical catch to that is you can’t plug the headphones into the computer. They have to go into the interface, mixer or microphone.


No, I don’t recommend listening on earbuds. They were handy for the photo.