ACX check


My name is Patrick, and I am about to begin my audiobook career on ACX, but I am trying to meet all the recording and mastering requirements before I start auditioning. I have Audacity 2.0.6, and I am not sure how/where to go to to do the following: to make sure my RMS level is set between -23 to -18dB, to be certain my peak value is set to -3dB, to make sure my noise floor set at -60dB or higher(?) (I am wondering if I need to go to the “Compressor” Effect because I saw the Noise Floor slide bar, and it was set to -40dB - is that good to go and where I go if I were to adjust the Noise Floor level?), and then lastly, to make sure the kbps is set to 192.

Is there anyone out there who can help me solve this, WITHOUT getting to techy on me? Just straightforward effective answers that will tell me exactly what I need to do. And please DO NOT tell me to go explore the manual to try and find the answers there. I already have, and there is no clear cut way to find the answers to these very specific requirements. That is why I am here now asking. Please do not interpret this message as frustrated or fed up - just want to be clear that if anyone is going answer this that they NOT be just as vague as the situation already is.

Thanks! And appreciate the help!

  • Patrick

You can’t adjust the noise floor by turning a knob. Or by making a setting in Audacity.

The noise floor is the sum of mic noise and preamp noise with background noise picked up by your microphone.

Part of it is pure hiss (white noise) and some of it is natural noise (wind, breathing, other sounds).

-60 dB is where its starts to get annoying. Most decent mic/preamp setups will give you -75 dB. But a noisy environment will easily add 20 dB and then it 's worse: -55 dB…

So, turn off all fans, AC, the fans in your recording computer, the refrigerator… Make sure there’s no draft from open windows. Cut room reflections with blankets…

Start with recording silence. Listen to it. See if you can pick out noise from appliances and such. Maybe you need to amplify the recording in Audacity to hear them.

I published a couple of helper documents and there are internal tests that mimic those at ACX. So you can create test clips and check them against the known standards before they ever leave your house.

Is there anyone out there who can help me solve this, WITHOUT getting to techy on me?

Sure. Hire a recording engineer to set you up and get you through the first few books and teach you how to do it yourself.

You’ll still have some techy to worry about, but you won’t be spending weeks going back and forth on the forum to solve them all. If you don’t do it that way, you are the recording engineer. The longest running thread on the forum is Ian who only wanted to record his voice for audiobooks from his apartment in Hollywood. He succeeded. It took a little over a year.

I’ll get these documents together. Have you ever installed an option in Effect > Equalizer or added a custom filter to Audacity?

As we go.


Another note. This is the Audacity Forum, not a help desk. The elves are in and out as their time zone rolls around and we each have our areas of interest.

If you happen upon someone who needs help and you happen to know the answer, by all means post. Forum: Users helping Users. Your first few postings will be moderated until we’re sure you’re not going to try to sell us Male Enhancing Devices or Life Insurance. Past that, you’re good to go.

We live on details, so if we ask you to describe your setup, equipment or computer, etc, be detailed and don’t abbreviate model or version numbers.

What is your computer and operating system? We can’t supply good support for earlier Audacity versions (like yours), so start by getting Audacity 2.1.0 from here and installing it.

You might also get the two add-on packages, FFMpeg and Lame, while you’re there. You’ll need “lame” to make the MP3 sound file for ACX.


Thanks for the responses and the tips, guys!

And, Koz, just to put you at ease - I am here to ask questions is all - not sell Male Enhancement devices or Life Insurance (not sure where that came from or what made you think of that?). And I know it’s not a 24/7 help desk. I know it’s a forum that people are coming and going through at their leisure. If I see a post that I can be of assistance to - I will gladly give the advice - no need to worry about that! :wink:

Ok, that’s great, Koz! If you could post those helper documents I think that would be a great help and a good place for me to start! I appreciate that - thank you! Are you going to post them here on the forum, and then I just download them? Or another way? And then how does it work from there in regard to aligning the test recording with this specific document to see whether I am at the requirements for ACX or not? And if it does not meet every requirement then would I have to download the 2.1.0 in order to be instructed on how to fix the settings?

To answer your questions - I have an HP Pavilion Laptop, and by you asking, “what is my operating system”, I am taking that you’re referring to my equipment? I have a Focusrite Scarlett 2i2 interface with Scarlett Studio condenser mic. Does that answer your question? Also, I do have Equalizer as an Effect. Let me know if you need more specifics from me.

Cyrano, are you basically saying that Audacity automatically assesses the noise floor by your background noise and will list it at -75 or -60 or -45dB based off what it is detecting to say what the Noise Floor is?

Thanks again!


I am here to ask questions is all - not sell Male Enhancement devices or Life Insurance (not sure where that came from or what made you think of that?).

You don’t see all the people trying to sell stuff on the forum. No, thanks. I don’t need SAP Development training in Mumbai. We didn’t used to be fully moderated, but that proved unworkable. We got overwhelmed.

what is my operating system

Windows? Which one? I’m typing on a Mac, so if there are computer specific comments needed, I may need to wait for help.

I collected a number of handy documents and links at the top of:

I’ll pick them out and describe them as needed. The top bunch are from ACX and related companies. Those are their training videos and links.

I generated a format to use so you can submit test sound clips on the forum in such a way that we can get the most use from them.

The forum will not allow you to post pages and pages of spoken word. Sorry, it just doesn’t. Do you have a service such as DropBox which will let you post longer pieces? Close to the end of testing we may need that. Testing ten second clips is nice, but sometimes we may need to examine a whole chapter or longer work.

Do not make a very newbie mistake of reading a whole book over months and only then submitting it for ACX testing. Chances are terrific you will be reading it all again at better quality. The elves regard the phrase “Clean Up” as code for “unrecoverable presentation.” Like the posting: “Can you help me clean up…”

You’re dead.

So if you already have a recording environment (studio) set up, prepare a test clip according to that recipe and post it here. Do Not Help Us.

Post clean, unprocessed work.



Unzip acx-check.ny and copy it to the Audacity plugins folder. Restart Audacity.

Open any voice work (like the one you just made). Select the whole thing by clicking just above the MUTE button.
Analyze > ACX Check.
That will give you a panel with lots of technical specifications and the three you really need: Peak, RMS (loudness) and Noise.

It will also give you a metaphorical gold star on the bottom if you passed. That’s not likely, not because you led an impure life, but just that very few home recordings pass.

Rather than plow on, I think I’m going to stop there. If you get stuck, post where and at what step. Also note if something doesn’t work right. You did install Audacity 2.1.0, right? Some of our tools don’t work as well in earlier versions.


“Operating system” is OSX vs Windows 7 vs LINUX. I’m guessing some version of windows on an HPlaptop.

Cyrano, are you basically saying that Audacity automatically assesses the noise floor by your background noise and will list it at -75 or -60 or -45dB based off what it is detecting to say what the Noise Floor is?

There is nothing automatic. I’ve written a plugin to assist in checking your recording called “acx-check”. You can download a beta version here: There are instructions on how to install plugins here

To use the tool make a test recording with the volume controls properly set. Include several seconds of silence – as in sit still and hold your breath. The tool will report the peak level, RMS level, noise floor and a bunch of other stuff.

No, I’m just saying the words “noise floor” mean the sum of all noise in your recordings. Audacity doesn’t measure that.

Where are you seeing Audacity list a noise floor in dB?

Again thank you all for the responses and help - much appreciated!


1st- I have a PC - Windows 8 HP Pavilion laptop, but I have the Windows 7 start menu (if that’s something you should know?)

2nd - I do have Dropbox to send larger files.

3rd - … - So I’m just a little confused - If I can see if the audio is at the exact specifications for ACX’s requirements or not just through this link, why would I need to post samples on this one - … _Clip.html? I’m just asking this to understand why the latter link is necessary vs. the ACX one is all.


So just keep silent? Don’t say anything at all in the test recording? If the RMS, Peak Value, kbps, and noise floor are not at ACX’s requirements based off the ACX-check what then? Re-record and start over? Or can I fix that myself so I won’t have to re-record and such? Are there instructions in the download on how to fix the settings?

So in conclusion to what you’re both saying, Koz and Flynwill, I need to:

  • first download the newer version of 2.1.0 & then download the acx-check.ny and then just go from there?


I didn’t see any specific listing. I just was trying to understand further what you were saying, and it just seemed you were saying that the noise floor is all dependent on the surrounding area of the studio and the studio space itself. But what I am confused about is if in the context of where the noise floor is not where I need it to be there has to be a way for me to fix that, and it seems the only way for that is to have a very quiet space, which I do. I’m just keeping in mind that even if my space is really quiet and the dB is showing -55 or -45 - what do I do then? That’s where I’m getting tripped up. When I went to the “Compressor” Effect I saw the Noise Floor listed under that, and so I thought that was where I could change it, but I guess I’m wrong in thinking that.

Thank you all! I really appreciate your help and kindness in helping!

  • P

If I can see if the audio is at the exact specifications for ACX’s requirements or not just through this link

That link is to download the software that allows Audacity to analyze your show. It adds a tool to the Audacity Analyze menu.

You can totally get Audacity to analyze your work without that tool. That’s what this page tells you how to do.

ACX Check is much nicer.

Please use this format to record a test clip.

We not only need a sample of your room noises (officially “Room Tone”), but a sample of your voice and the relation between them. Proper recording is a juggling act between all the pieces.

Use the bumper sticker version of the Record A Clip panel. Hold your breath and don’t move for two seconds. Announce normally for eight. Stop. Export WAV (Microsoft) and post it. You should not be doing anything in MP3 during production.

That, too is a very newbie problem. “How do I get my MP3 to sound better?” You don’t. Once you have compression damage in MP3, it’s permanent. You record the show over again. Use WAV (Microsoft). It’s a perfect quality sound format that will play on all three major computers.


and the dB is showing -55 or -45 - what do I do then?

You can wait until you have the basic tools installed and working. If you get too far ahead, you can be fighting problems that are easily solved using tools we haven’t covered yet. Improper use of compression can make noise problems worse.


Senior Elf Steve designed a sound filter called LF Rolloff for Speech. It’s a rumble filter. Rumble, thumps, thunder, earthquakes, trucks & busses going by, etc, etc, do not contribute to a voice recording and those sounds can screw up some of the Audacity effects, filters and tools. This filter strips those sounds out of the show. It can cause some sound damage if you have one of those double-bass, radio broadcasting types of voice. See: Don Lafontaine
In that case, we have to do it a different way.

Download that ZIP file and unzip it to LF_rolloff_for_speech.xml. This one’s a little more involved than just dumping a file into Audacity and go to lunch. It has to be installed and you have to pay attention.

Adding Equalizer Curves
– Select something on the timeline.
– Effect > Equalization > Save/Manage Curves > Import
– Point at LF_rolloff_for_speech.xml > OK. (it won’t open the ZIP. You have to decompress it)
– LF Rolloff for speech now appears in the equalization curve list.

Also from the Audacity instruction book.

LF Rolloff for speech is used with the filter length slider all the way up. That will make more sense when you get closer to actual production.

Let us know if you have any trouble with that, or any of this so far.


How’s that test sound clip coming along?


OK, so got it in terms of sending a test clip and which link to go to to do that.

Now which one is ACX-check - this one: ? Or this one: … sting.html ?

In regard to the test clip - I haven’t started yet because I tried downloading 2.1.0 first, but it’s showing to download 2.1.1 when I clicked on the link you sent me to do that. So I am really not sure where to go to find that exact version. Is there a list of versions to choose from on Audacity to download? Or should I just update to 2.1.1 ? I tried sending out a message about that earlier, but after scrolling through the messages it didn’t seem to go through.

The grand, earth-moving shift from Audacity 2.1.0 to 2.1.1 happened while I was typing. Nod off for a second everything changes. Use 2.1.1.


NY files were not produce in New York, but they are “nyquist” programing language that Audacity understands. They’re made of semi-English words. You can open them up in a text editor and read the first few comments. The two should be exactly the same thing. That’s the intention. Version 1 Release 0.3. We’re inspecting an upgrade.

;nyquist plug-in
;version 1
;type analyze
;name “ACX Check”
;action “Compute statistics about clip and compare to ACX requirements”

; 2015-05
; release 0.3

; Set the output format (example: 53.3 dB)
; Note it would be really nice…

So use either one.

Please note that none of this will prevent you from recording a ten second clip and posting it. See attached picture (you may need to click on it to see the whole thing). Underneath your text message posting, you will find the Upload Attachment > Choose File tabs. Pick your WAV file and OK.

This is a recursive picture. It’s an illustration of a picture of the screen you’re using. It should give you a headache.

Screen Shot 2015-07-16 at 20.45.55.png

I promise not to get too techy.


Ah, I see. OK, I will go ahead and download 2.1.1. Thanks for the clarification on either link for ACX-check.

I promise not to get too techy.
(Chuckles) Thanks, Koz. You’ve been very helpful. As well as you flynwill and cyrano.

Ok. I will get to work on this. I most likely won’t have the test recoding up until tomorrow (or now today for me) - 7/17/15. So just be on the look out then.

Thank you again and will be in touch,


Here ya go, Koz.

In WAV (Microsoft 16 bit). Does it matter if it’s in that or 32 bit?

It should be exactly 10 seconds long - 2 seconds quiet and then about 8 secs. talking.

Let me know if there are any problems. Shall I just go ahead and download the ACX-check? Or wait 'til you’ve heard the audio?

Yes. Go get the testing tool. It’s easy to get so lost in the weeds that you forget to actually make sound files.
As we go.


There’s nothing particularly magic about the file length. If you make it too short, there isn’t enough voice to analyze. If it’s too long, the forum will refuse to accept it.