Help! Balancing ACX specs

Hi folks, I’m hoping a more experienced Audacity user can help!

I’ve got a bucket of files to remaster to specs but can’t get all 3 requirements to ‘PASS’ the Acx Check plugin.

Here’s some typical values I get before being stymied:
Peak Level: 3.0 (pass)
RMS Level: -27.7 (fail)
Noise floor: -86.5 (pass)

I normalize, compress, normalize again, tweak RMS…can’t pass all 3 specs. Any solutions out there?

I’ve got a bucket of files to remaster

Remaster? Have you got the original readings—before you did anything to them?

We publish an Audiobook Mastering Suite of tools. Apply them all, in order, don’t add any steps and don’t leave anything out.

The settings should stick. Once you put the numbers into the tool, they should stick there time after time. I can rack through the whole pile in about 20 seconds. That’s taken from here which is a more detailed explanation and will tell you where to get tools from if you don’t have them all.

The suite guarantees ACX Peak and ACX RMS (loudness) and if you recorded in a quiet, echo-free room, you may pass Noise and be done.

However. If we’re following someone else processing, this may not go so well. ACX is sensitive to funny sounding voices from having applied too many effects or effects with too strong a setting. There is no making a trash recording and beating it with a stick until it passes. It may pass the technical restrictions but it will never pass Human Quality Control where a real person listens to it.

These are descriptions of numbering values and the ACX Specifications.

Post back if you get stuck anywhere.


Success! Thanks much, Koz.

I don’t have the ‘Limit Curve’ plugin on my version of Audacity, but learned that it’s a later version of the ‘Equalization’ effect.
The required fields are also in Equalization, so I tweaked them, applied the RMS Norm & Limiter effects and it worked perfectly.

Looking forward to remastering my bucket of audiobook files.

BTW: Yes, the files WERE previously mastered, but thankfully not so radically that the remedy didn’t work :slight_smile:

That equalizer curve is kind of a big deal. You can recreate it manually from here.

These are the text points.

LowRolloffForSpeech.txt (299 Bytes)
And this is the XML file you could import into earlier equalizers

LF_rolloff_for_speech 2.xml (299 Bytes)
The curve is a balancing act between getting rid of “rumble” sound which many home microphones and sound system have (and can throw off the other tools) and affecting the voice. This filter or one like it shows up on field sound mixers and helps with wind, thunder, earthquake and other low pitch interference.

If you’re using an earlier Effect Equalization, the length slider should be about 5000.