Editing and Spacing with Alex the Audio Scientist

ADBLCRE-ACX_Character_IconHi, folks! I hope you’re ready to learn, because today, I’d like to kick off fall audiobook production lessons with three facets of your post-recording process:

Editing, QC, and Spacing

Audiobook editing is both an art and a skill. The aim is to achieve a clean, professional-sounding audiobook that elevates the source material. It consists of a two-step process commonly referred to as “Editing and QC.”

Step 1: Editing:

  • Remove extraneous sounds from your recording (mouth noises, pops, keyboard clicks, etc.).
  • Modify the pace of narration, if necessary.
  • When appropriate, portions of the recording that are edited out are replaced with clean room tone.

Step 2: QC (Quality Control):

  • Listen to the audio while reading the manuscript to ensure they match exactly.
  • Mark down any errors (misreads, mispronunciations, or noises you can’t edit out) to a QC sheet, which will be used when you rerecord. You can find the QC sheet Audible Studios editors use here.

Once you’ve completed the QC step, you’ll rerecord the errors you’ve marked and re-insert them into your original audio files. These rerecorded sections of audio are sometimes called “pickups.”

A Pro Tools session featuring unedited, or “raw,” audio on top and edited audio below.

Editing Ratios

Audible Studios’ editors aim for a specific ratio of time spent on the edit or QC to the audiobook’s overall running time to ensure that these steps fall within the schedule and budget of the full production.

  • When editing, the ratio should be 3:1, or three hours spent editing for every one hour of recorded time.
  • For the QC process, the ratio should be 1.2:1, or 72 minutes of QC for every 60 minutes of recording.

If you find yourself working faster than this, I recommend a second edit and QC pass to make sure you haven’t missed an error. If you’re consistently taking longer than recommended, you may be focusing too much on certain aspects of the edit. Try listening to some samples and reading reviews on Audible to learn what really bothers listeners.

One way to stay within these guidelines is to speed up the playback in your DAW, so that you cover more ground than at the normal speed. While this may take some practice, it can help ensure that your editing is done quickly and correctly. If you go this route, I recommend you start at 1.2x speed, working your way up to 1.5x speed, as you get more comfortable.

To learn even more about the editing process, watch this video from the experts at Audible Studios.


When it comes to spacing, ACX’s requirements help ensure that your audiobook productions stand shoulder to shoulder with all the titles on sale at Audible, Amazon, and iTunes. Our requirements state:

Each uploaded file must have between 0.5 and 1 second of room tone at the head, and between 1 and 5 seconds of room tone at the tail.

Editor’s Note: We’ve since adjusted our spacing requirements to improve the listener experience. The current requirement states that each uploaded file must have no more than 5 seconds of room tone at the beginning and end.

Why is this so important? Think of the spacing within your audiobook as the layout of words on pages and of pages within chapters of a print or eBook. Without proper spacing denoting the end of a scene or beginning of a new chapter, your listener could feel lost within the book, and the impact of your narration may be lessened. The easiest way to follow this requirement is to paste in the appropriate amount of clean room tone at the head and tail of each file.

I hope this gives you a good understanding of one of the most important aspects of audiobook production. Check out my other posts for more audiobook production education, and come back soon for more tips straight from The Audio Scientist.

Quick Tips for Editing and Spacing:

Make sure you have clean room tone. If you don’t, you could be creating more problems than you’re solving.

Record new room tone any time you change your microphone or studio settings. The old room tone may not match the sound of the new recording you are applying it to.

Always wear headphones. You need to be in an isolated environment to ensure the narration stays natural and any cut is seamless.

Get into the habit of marking everything. If you find a click, pop, noise, or QC error, make sure you mark the instance within your DAW! That way, when you go back to make the edits, you won’t have missed anything.

Like what you read? Subscribe to the ACX blog to get updates every time we post!

11 responses to “Editing and Spacing with Alex the Audio Scientist

  1. Some of us have been around long enough to have known the joys of reel to reel tape, razor blades and china markers (ahem,) but many of the folks narrating today don’t have the benefit of having engineers and/or directors and they’re reading directly off a computer screen. This creates some challenges for tracking, editing and identifying pick-ups down the road.

    It’s wise to have a second person present – with headphones – but outside the booth or closet during recording sessions for many reasons (like yelling, “I’m out of coffee!”) This person can track your mistakes for you – while you focus on the script. Using a paper script and doing mark up (red pen) is most efficient. Lately we’ve even tried using an ipad, a pdf version of the script and the ibooks highlight function to identify edits. Results have been a mixed bag.

    For folks doing everything themselves, (narrating, editing, fetching coffee) it is far more time consuming to try to edit by ear without an edit guide, however, the results are often just as good if not better than following an edit guide. Because you’re developing the overall production through critical listening for “the best take,” adjusting pacing and hearing the final product emerge, one sentence at a time. You’re also far less likely to be surprised by a missed edit in that final pass.

    Striving for time efficiency is a great goal but only if quality isn’t sacrificed along the way.

  2. Thanks, Alex! Could you answer a quick question for me as well? I use Audacity and have my leveler and normalize set so that my audio falls nicely within ACX’s guidelines. Having done that, do I actually NEED to compress as well, or do the level and normalize cover this?

    • Hi Wendy
      May I ask what your leveler and normalise are set to on Audacity to stay within ACX Guidelines?


  3. This article may be helpful for all the noobs who have never recorded or edited before. Otherwise, it is just common sense and seems like filler material. Kind of wish I hadn’t wasted my time reading this. It’s like, “In order to make grass grow, you must occasionally water it. To make grass look nice, you should pull weeds.” etc.

  4. Pingback: Regarding Room Tone with Alex the Audio Scientist | Audiobook Creation Exchange Blog (ACX)

  5. Pingback: A Critical Ear: The ACX Reference Sample Pack | Audiobook Creation Exchange Blog (ACX)

  6. I have recorded for ACX for a few years now and have never had files refused for either too low or too high db. I am recording in exactly the same way, yet am told that my mp3 files are too low. Have ACX changed their requirements ? Please help as I am beginning to panic as I have to complete a book for an author.

  7. This has just happened to me as well. I have not had a rejection ever either. It says my RMS is -30.3 with Audacity. When I check the RMS on other chapters they are pretty much the same between -27 ad -31

  8. donna m bachman

    ditto. Im on audition and my previous books went through fine and now it says I’m too low

  9. My book just got rejected for room tone at the beginning and ending not being right, and it is requesting I resubmit them all. I just checked my files, and all but my audio sample were between .5 and 1 at the beginning and 1-5 at the end. It is completely silent, as I did use the noise remover in audacity. Would that cause an issue?

  10. Also had a rejecton for room tone spacing. They asked for ALL files to be reviewed and gave an example of ONE that had failed. Yep, the file had too short a tail. BUT… did others fail? I’ve checked and they seem okay. I have a short piece of ambient music at the start of the chapters which starts out very quiet (sounds really nice) and BEGINS just short of the 1 second HEAD they specify. The actual narration starts at 2.2 seconds. Now… is it okay to just have 0.5-1sec of room tone before the music? I can’t hang about for another 40 days after submitting again to find out. Looks like I can forget getting my titles out for Christmas then.

Leave a Reply to Andy Severn Cancel reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s