Peak and Floor levels

OK, Coach … will do … and, yes, I’m uploading at the 192 rate (thanx to your coaching)

Any word from ACX? They’re going to have to unscramble you since you posted both a test and a chapter.



Koz, ACX answered my question as to whether I should upload one Chapter at a time … or all at once at the end … and their answer was ‘either way’

So maybe I’ve finally made a helpful and informative post rather than endless questions.

Thank you. We’re happy it’s all working.


When I go back into the Master Edit file. the sound track is condensed … how do I elongate it up to it’s actual length which will enable me to find and delete a given section?

Koz, need your thoughts. I followed your tutorial and workflow for first 6 chapters and it was flawless.

Then came Ch 7:

  • held for 5 secs of absolute silence
  • recorded chapter
  • exported as wav file
  • applied the following effects that you had set for me (filter curve, then RMS Normalize, then Limiter and then ACX check
  • ACX check showed all had passed
  • then applied Noise Reduction … but then the ACX Check failed

So I went ahead and recorded without the Noise Reduction … and when I was finished with everything, the ACX check was fine.

Sooooo … is that possible that on occasion you don’t need Noise Reduction? Did I do right or did I screw up (again)???

the sound track is condensed

I assume sideways.

Audacity will always try to display the whole show whether it’s convenient for you to work on it or not. You can use the Zoom tools to make a small section of the show larger left to right. There’s a lot of different zoom tools, but I only use three.

Drag-select a portion of the show and zoom into it with Control + E. Repeat as needed. If you go in too far, you can back out a little with Control + 3. Zoom out to the full show with Control + F.

While you’re zoomed in, you can slide the timeline left and right with Shift + Scroll-Wheel.


Noise is as close as we get to black magic.

So I went ahead and recorded without the Noise Reduction

What you’re supposed to do is open up the raw WAV file. That’s why you saved your first raw recording—and hopefully copied it to a safe place. Another good possibility is Edit > UNDO until you get back to the original recording. Audacity will peel off all the corrections you made one after the other. If you closed Audacity, then you’re stuck.

  • ACX check showed all had passed
  • then applied Noise Reduction …

ACX Check said you passed noise (third number) so you applied Noise Reduction?

but then the ACX Check failed

What part failed and what did ACX Check say about it?


If you record well in a quiet, echo-free room, it should be possible to apply Audiobook Mastering and pass everything. Noise should pass by at least -65dB (quieter), not just the ACX limit of -60dB.

If you can do that, then it’s export an Edit Master WAV and go on to the next chapter.

ACX likes all their chapters to match, so whatever you do to one chapter should be done to them all. This is the one that kills people if they get to the last chapter and it just will not pass without extra steps.

People who have badly damaged recordings have a list of different corrections and filters in addition to Audiobook Mastering. Their chapter productions are major time-consumers, and that’s assuming they don’t make any mistakes.


Koz, I did another chapter this morning and did not apply noise reduction because after I had done the first three steps, the ACX check everything passed … so I skipped the noise reduction and completed the chapter and did the exports as directed. When I finished everything, ran another ACX check and everything passed … again without using the noise reduction.

Later today or tomorrow I’ll do another chapter and see if the same holds true after the Audiobook Mastering (i.e., everything passes the ACX test without applying noise reduction). If that’s the case, I’ll go ahead and apply Noise and see what ACX then says and specifically to which area. Stand by and I’ll let you know.

Noise isn’t a Pass/Fail thing. You should pay attention to the actual numbers. The ACX Noise limit is -60dB. As long as your noise numbers are quieter than, say -65dB, you should be good to go.

If most of your noise settles around -62dB or -63dB, that’s too close to the limit and you risk having some chapters make it and some not.

When you run ACX Check after mastering, what are your noise dB numbers?


Just finished a new chapter and ACX was:
Peak 3.4
RCM 20.3
Noise 70.3

Noise 70.3

Then you don’t need additional noise reduction at all.

If you can do that and sound OK, that’s all it takes.


Koz, a related question. Once I’m done with a chapter (editing and all) I end up with three files:

  • a wav file
  • an Edit Master wav file
  • and an MP3 file

Do I need to keep all 3 files on hand or just the Edit Master and MP3 ???

That first file is your raw reading, right?

I would keep all three, but the throw-away is the MP3. You can’t edit it or change it without causing sound damage. You can make a new MP3 from the Edit Master and you can make a new Edit Master from the raw reading. No question keep the first two. I still have raw readings and delivered WAV masters from years ago.

Be able to point to two different places that have your Edit Master. Inside your computer and USB thumb drive as an example. Second places can be external drives or cloud storage—or another computer.

Two different folders in your computer does not count.


Koz, thanx for tip above … I have everything backed up on an external hard drive and also on Compuserve

Now a question:
When you gave me the Hum link, I had already recorded a couple of chapters. Can I go back to those particular chapters, go to the Edit Master and retroactively apply the Hum removal effect and then save as a v2 Edit Master and a v2 MP3… or will that affect something else? In those chapters, the noise level currently is ok by ACX standards (around -65 or so) but with the hum removed it jumps to mid-70’s