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’ve been using lately, because I was reminded recently that it still exists, and still works great.
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 the issue of 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.
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:
So, go grab it.
Hope this helps.