Hey there!

A lot of people consider me to be one of the very first people to podcast. I did a lot of it. And from that world, comes a tool that is very useful if you’re reading audiobooks, especially if you want to be compliant with ACX standards in one simple step.

Because audiobooks are listened to by people in high noise environments (cars, trucks, planes, etc), it’s imperative that every single word you say as an audiobook performer gets heard.

And sometimes, when you have a microphone with little or no pre-processing, the levels you speak at can vary greatly.

These two facts are at odds with one another.

One solution is to add compression to your audio, either with a microphone pre-processor, or in your sound software. In ProTools, you can use RMS normalization, as described in ACX’s production and mastering standards:


There’s yet another tool that I use, that has been orphaned from its previous use, but still works great. So, I now also teach others how to use it, both in the VO2GoGo curriculum and in the project I do with Dan O’Day, the ACX Master Class.

And it’s free.

It’s called The Levelator. A group of podcasters, led by Doug Kaye, created it a few years ago to solve a thorny interviewing-over-the-internet issue: two people talking on a podcast at different levels with different microphones.

The Levelator scans your original audio, adjusts the levels of the audio as it goes along, and when it’s all done, creates a new version of your audio that, well, just sounds better.

Why? Because the levels have been adjusted so that they are uniform – uniformly louder. Which means that this tool that was created for podcasting, works great on your audiobook audio as well.

Prep your raw voice tracks with The Levelator, then use your audio software’s tool to finish the job before turning it in.

Warning – a moment of geekspeak ahead: Levelator does exactly what ACX wants you to do with your audio: root-mean-square (RMS) normalization at -20 dB.

But, there’s one last thing you need to do: adjust the peak normalization (as opposed to the RMS normalization – they are two different things).

Levelator will create a new .wav file, in the same folder as your original, that has the suffix “[filename].output.wav”. Open that file in Audacity, and use the Normalize… function to reduce that -1.0 db to -3.0 db. You’ll see the height of the waveform reduce slightly (Oh, and yes, do leave that first box checked, the one that says “Remove DC Offset”)

Then, export your audio as an MP3 file and upload to ACX.

There. Geekspeak over.

Oh, and just in case you’re thinking you should peak normalize before exporting, don’t. The Levelator does its own normalization – plus, you won’t be able to match your performance and volume if and when you have to do pickups with the raw audio if you’ve normalized it. Just leave it alone.

The Levelator is available for Mac OS X, Windows and Linux. And, again, it’s free. Just launch the Mac App Store on Macintosh. Information on Windows and Linux version to come.

So, go grab it.

Hope this helps.



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  1. Hi David, hope all is well.

    Comparing the Levelator to compressing a file (5:1) in audacity, does one produce a better end result than the other?

    Thanks. Bob

  2. I use levelator for a local acting podcast that I produce and I get compliments all the time on sound quality.

  3. Yes, it seems to bring the volume of the entire project up as well. What software do you use to change the Wave file into an Mp3 with a 192 bit rate?

    1. That would be Audacity, the same software I specify for recording and editing. You import it back in as the output wav from Levelator, then export as MP3 192 Mono.

      Hope this helps!


  4. Hello, everyone out there! I’ve downloaded “Levelator”, but my Mac won’t allow me to “open” it because it is not from their App store. Has anyone out there encountered this and, if so, how did you overcome this obstacle? Any suggestions are much appreciated.

  5. Hey I do podcast editing, However, I usually run the levelator after the whole thing is mixed after the DAW. I guess I’m doing it wrong? Lol

    If not, do you have any thoughts on this using levelator before or after the whole vox is mix, is there a difference? Regards and thanks ahead!

  6. I’ve been using Levelator ever since David first recommended it to me in his class for audiobooks. I use it on commerical auditions, too. Frankly, it’s no brainer quality has been a life-saver for someone like me who’s got little experience applying effects in audio applications. For some odd reason, techies like too poo-poo it, but trust David and me on this one. It works!

  7. David, Not to “suck up”or inflate your ego, but your suggestions, recommendations and other offerings are like a Chic-Fil-A sandwich…PERFECT EVERYTIME!

    All of us who take the time to say a hearty “thank you” for all you do for us are TRULY speaking fro those who don’t take the time!

    With MANY thanks,
    Stu Norfleet

  8. I got the impression that we shouldn’t use the levelator for commercial auditions. Has that theory changed