Recording for Audible ACX - Technical Post

I need to write this entry for my wiki anyway, so I thought I'd make it a blog post as well in the hope it might help other people getting started with Audible ACX narration. That said, this post is technical in nature and only covers that portion of the process. I'll write another post once my sound studio is finished that discusses sound attenuation for audio recording. Suffice to say for now that you need a silent, sound-dampened environment to work in, since it's virtually impossible to scrub sound artifacts from a recording without sacrificing quality.


I use Audacity and an AT2020 USB Microphone on a MacBook Pro, but your mileage may vary. I recommend all three, since Audacity is free and robust, the AT2020 is a great mic and the MacBook Pro is a workhorse for content creation.

Both Audacity and the microphone should be left at their default levels, making certain that (Mono) Input Channel is selected from the dropdown menu at the top middle of the Audacity program window and 44100 is selected as the Project Rate (Hz) in the dropdown menu at the lower right. This is important because changing the default levels of your recording software and microphone can throw the audio levels off and cause your project to fail the ACX QA test.

When recording with Audacity, I use a process I learned from I click the record button, read until I make a mistake and then click the stop button. Directly thereafter I click the fast-forward button, which causes the next block of recording to begin as a new audio track beneath and forward of the first one. When I'm finished with the piece I'm working on, I begin editing with the last audio track, copying and pasting backward over my mistakes until I reach the beginning and have a complete and contiguous audio file with no mistakes in it. For more information on this method and a comprehensive class on recording for Audible, check out "Recording for with Audacity".

Finally, among the Audible ACX Audio Submission Requirements is a requirement for beginning and end silence at the front and back of each recording and a space of silence between each chapter name and the start of the following chapter body. Let me break that down for you:

  • .5 to 1 second of silence at the beginning of each recording.
  • 2.5 seconds of silence between a chapter name and the beginning of that chapter body.
  • 3 to 5 seconds at the end of each recording.

You can meet this requirement easily by leaving plenty of silence before and after each recording while you work and then cutting it down to size.


You're bound to have mouse clicks or perhaps even a few heavy breaths in the final recording. I eliminate these right away with an Audacity plugin called Noise Gate. To do this, select the entire contiguous recording, click on the Noise Gate plugin in the Effect menu and run it at the default settings. This creates a nice, quiet baseline in the work and softens those breath sounds. For a more comprehensive tutorial on this process, check out Olivio Sarikas' YouTube tutorial, Remove breathing sound from your audio recording // Audacity. You'll also have to download and install the Noise Gate plugin, so here's an instruction page for that: Audacity Plug-Ins and Libraries.

Once you've done this, you should export the Audacity file as WAV 16 Bit PCM. This will be a large, lossless file that you can then manipulate further. Take that file and run it through Levelator, which will compress your recording and make it equally loud throughout so that it can be heard easily with headphones, over ambient noise, etc. Note that Levelator is no longer being maintained by its developers as of 2012, but the final program still works well on on my Mac, and I know a number of people use it for Audible ACX post-production work.

Levelator will spit out an output file, which you should import back into Audacity and export again as a 192 Bit Mono MP3. That's your final file. Name it appropriately and upload it to ACX.

End Notes

Keep everything. I keep backups of each stage in the recording and post-production process; the original Audacity project, a separate project for the contiguous recording before it is altered, a copy of the WAV file and of course, a copy of the MP3.

Finally, this is by no means a comprehensive look at the technical elements of recording and post-production for Audible ACX. It's meant to help you fill in the blanks if you already have some facility with Audacity or other recording software and are somewhat comfortable with the Audible ACX Submission Requirements. If you aren't, then please let me again recommend "Recording for with Audacity". Yes, it's a bit pricey, but so is your equipment, and you shouldn't skimp on that, either.

Okay, that's it! Hope I helped. Now to port this into my wiki.


I have it from the folks at Audible ACX that you don't need to include end matter such as listings of forthcoming titles, indices or other notes in your narration, though you might choose to if you wish. This might be especially important for hybrid or self-published writers who like to include a request for reviews or a URL to their newsletters at the end of a story or novel in ebook or paper formats.