How to set RMS on recorded chapters

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.


hmmmm - so what do I plug the headphones into? Some kind of amplifier? I was just getting used to a nice pair I found at Sweetwater (in my price range!) Tascam. would another piece of equipment fit in my wee studio? o dear.

Hope you do get a chance to check out my finished book (sometime this summer! at this rate!) you can also visit my site,, where I am about to post a chapter, using the handy hum remover. :smiley:


what do I plug the headphones into?

I rolled back through the forum messages and you never told us what your microphone or recording system is.

What is it? Descriptions and model numbers welcome.


I have a 2012 13-inch Macbook Pro running High Sierra OS 10.13.2 - a microphone on loan Lewitt DGT650, and Tascam TH-02 headphones (jack goes into the MacBook) And Audacity 2.3.3 :smiley:

I’m afraid this set up is partially prehistoric…I’m working in the corner of a closet measuring 2.5’’ by 4’ and approx 7.5 ’ high

At least, I’m having fun; and genuinely want to do this work…thanks again!

just did a short recording (posting it to today) While it met peak value (3.8) it was 28.6 RMS and 59.6 Noise floor

I ran Filter Curve as specified, RMS Normalize (target RMS -20) and Limiter (3.5) got all of it to work, but still heard a hum, ran remover as directed, still heard noise on the clip so ran noise reduction of the beast, then it sounded (to my ear) much better overall. 3.4 peak, RMS 20.4 and noise floor 76.7. (is this too quiet?)

gonna go outside and enjoy sunshine now ! :wink:

and a pop filter, of course!

noise floor 76.7. (is this too quiet?)

No. The Audiobook noise limit is -60dB and it’s recommended you hit it at least five dB quieter than that at -65dB. You’re at -76dB.

These are the relationships.

It doesn’t count if you go “Diving For Noise.” Set the listening system for normal performance volume and leave it there during the background sound. Some New Users crank the volume all the way up and complain about the “High Noise Level.” It’s not high. You’re listening wrong.

This is the address for your microphone manual if you didn’t get a paper version.

The microphone has a place to plug in headphones so you can listen to yourself correctly as you perform. It says so. What’s less clear is how you have to adjust the settings to do that. That can be your weekend chore.

There’s also a way to listen to computer playback so you never have to move the headphone cable.


Hello again Koz, just as a followup - I turned off my refrigerator indoors (I have another outdoors at the opposite end of the un-insulated house that I left on) turning off the indoor fridge did NOT make a difference! In fact the ACX check on the original clip was -55, louder than when I’ve recorded with this fridge on.

I did all the mastering steps, including hum remover and still had a buzz on the clip; when I ran the noise reduction, it went away. Noise floor dropped to 58 with hum remover, then 72 with noise reduction.

Do I have a very loud, humming rat in the walls somewhere? Next I’ll try turning off the outdoor fridge. This is going to be a problem if I ever record anything long, as we rely on our frozen foods out here in the wilderness…

Is there something else I’m missing? Thanks :slight_smile: :astonished:


Ah, thanks for the homework! :wink:
pluggin in the mic cable is not self-evident, I will look at the manual. Thank you again!

except I don’t appear to have
breakout box with a microphone port…

boy do I feel stoooooopid!