Can't find an ACX Check Plugin


I’m new to Audacity and I’m really needing help. I’ve been trying for the longest to download ACX Check Plugin and I can’t find it anywhere online. I keep seeing this link:
Missing features - Audacity Support

The problem is I only get a document download from this link, nothing I can use though. No plugin or anything. I’m simply wanting to create audio narrative files to be submitted to ACX (Audiobooks) without any rejections afterwards. Any successful knowledge that lead to solutions on this matter will be greatly appreciated. Thank you so much in advance.

ACX-Check.ny (4.4 KB)

Let’s see if I can post this without any damage. Also if it’s the right one. It should be the one by steve and be able to check long chapters… The earlier ones wouldn’t.


The new forum software messed up a lot of links and references. I have local copies because even though I’m not a developer, I was on the design team.

But yes, there’s a lot of stuff I was just going to leave as forum postings and they’re all gone, too.


That should be it. If you open it in a text editor, it should say 2.4.2-1. Close and Do Not Save Anything.

Do you know how to install a plugin?


How about Audiobook-Mastering-Macro? Do you have that?


It’s here:

How about Audiobook-Mastering-Macro.txt? That’s the troublesome one because it’s a text file and the forum messes with it.


Feel free to add it to - I believe that article is your forum post turned wiki turned support page anyway.

Thanks for the note. I need to wait for the coffee therapy to take hold.


No I don’t know how to install a plugin-I just installed Notepad ++ (text editor). I just got this message below-not sure what it all means:

;nyquist plug-in
;version 4
;type analyze
;name “ACX Check”
;maxlen 2143260000
;debugflags trace
;author “Steve Daulton”
;release 2.4.2-1
;copyright “Released under terms of the GNU General Public License version 2”

(defun getfloor ()
;; Calculate RMS where rate=10 Hz, window-size=0.4 seconds.
;; Return the lowest 0.4 to 0.5 s in the selection.
(let ((floor 999)
(window-size (round (* 0.4 sound-srate)))
(setf track (s-rms track 10 window-size))
;; Calculate new length in samples without retaining samples in RAM.
(setf samples (truncate (* len (/ (snd-srate track) sound-srate))))
(do ((val (snd-fetch track) (snd-fetch track))
(count samples (1- count)))
((< count 4) floor) ;stop at last full window.
(setf floor (min floor val)))))

(defun s-rms (sig &optional (rate 100.0) window-size)
;;; Like RMS function but also supports stereo sounds
;;; Stereo RMS is the root mean of all (samples ^ 2) [both channels]
(when (soundp sig)
(if window-size
(return-from s-rms (rms sig rate window-size))
(return-from s-rms (rms sig rate))))
(let (left-ms right-ms rslt step-size)
(setf step-size (round (/ (snd-srate (aref sig 0)) rate)))
(unless window-size
(setf window-size step-size))
(setf (aref sig 0) (mult (aref sig 0)(aref sig 0)))
(setf (aref sig 1) (mult (aref sig 1)(aref sig 1)))
(setf left-ms (snd-avg (aref sig 0) window-size step-size OP-AVERAGE))
(setf right-ms (snd-avg (aref sig 1) window-size step-size OP-AVERAGE))
(s-sqrt (mult 0.5 (sum left-ms right-ms)))))


I’m really trying I’m activate these links you’ve sent and I’m still struggling. Anything you have that is really user-friendly and helpful to the not so tech savvy would be greatly appreciated.

Audacity > Tools > Nyquist Plug-in Installer.

The Installer opens. Point to the ACX-Check.ny file > Do not allow overwriting > OK.


Analyze > Add/Remove Plugins > ACX Check > Enable > OK.

Open and select the work. Analyze > ACX-Check (No OK)

I’m going to start work on the mastering software. Post back if you have trouble.

Oh, This is a terrific time to force your machine to show you File Name Extensions. When you start getting three files with the same name, it’s good to know that one is a .png (picture), one is a .txt (text), and one is a .ny (Nyquist program).

As we go.


A few notes before we leave ACX-Check. Peak is intentionally slightly quieter than the -3dB standard on purpose. The conversion of your chapter from WAV or Audacity format to MP3 can cause slight volume changes. You will get flagged if your volume gets any louder than -3dB.

There is one internet channel telling people you have to hit peak volume exactly -3dB.

You don’t and you can’t.

Noise is the worst problem. I recommend quieter than -65dB. The standard is -60dB. Again, that’s for safety and most microphone systems can hit that if you’re careful with your environment and and microphone. ACX Audio Lab doesn’t check noise for you, so you’re on your own until the chapter is rejected.

If you created silence anywhere in your chapter, the noise reading will read -inf (infinite) and it will throw an error message. ACX may or may not accept that, but it’s an odd reading and should be avoided.

As we go.


I record with 45 dB ambient and have noise cancellation to sort that out no problem. Any more than 40 dB though and it affects the voice clarity adversely.

You should go up to the top of the forum…

…and start a New Topic.

It’s a terrifically bad idea to piggy-back on the end of someone else’s long post. The people who are likely to read and solve your question will never see it.


Kozikowskiiiii!!! Thank you so much! I really appreciate all your help. I finally got it to work. Hallelujah!

Cool. I thought we lost you. Solve the noise, too?

Fair warning that posting questions and responses on the forum is a lot like the four volume set “How To Ride A Bicycle.” It seems scary.

The first time you get all the steps to work you say, “Oh. That’s not too bad.”

ACX publishes detailed submission requirements.

Record your chapter in Mono (not Stereo) in a quiet, echo-free room. Include two seconds of hold-your-breath room tone at each end. Export a Protection WAV file—errors and all.

Correct the accidents, fluffs, stutters, mis-speaks, and pronunciation errors. Make it sound pleasant. Use “Room Tone” for editing and not generated silence .

Apply Audiobook-Mastering-Macro. Check the chapter with ACX-Check. Export your Edit Master WAV file. Export your 192 Constant-Quality, MP3 file for submission. Go make dinner.

That doesn’t seem too dreadful, does it? I can do a very entertaining soft-shoe at each one of those steps, but I believe that’s the whole world.

I think I mentioned somewhere at the top that my test submission (back with they allowed such things) was Practically Perfect in Every Way, but I got killed with mouth noises.

No retirement in a beach cottage for me.


I’ve been doing this for centuries and I’ve never set that down in one place.

ACX publishes Submission Requireents (chapter markers, etc.)


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