Producing first audiobook, noise levels and consistency.

After a lot of help from this forum, I’m producing my first audiobook on ACX.
Anyway, I’m easily able to get the recordings within the parameters demanded by ACX, passing the ACX analysis on Audacity, passing the test on ACX itself - but realise this by no means guarantees it will be okayed by ACX when it comes down to it.

I normally record at night to keep the floor level noise down, but sometimes do it during the day if all seems quiet. Difficult to be sure though, you can miss all sorts of background noise when you are recording!

But anyway, I’ve recently noticed people worrying that it can be turned down for the sound levels not being consistent with different chapters throughout the book.

After the mastering suggested here, here is what the first few chapters I did came out as after running it through the Audacity ACX analysis, with the RMS level for each chapter given next to its corresponding Noise floor.

All peak level -3.5Db.

RMS level Noise Floor
-20.57 -72.96
-20.70 -72.35
-20.76 -71.19
-20.48 -68.75
-20.65 -69.51
-20.74 -71.32

Do those figures seem as if they would cause any problems? (I realise it is impossible to go just by the figures themselves, but presumably they can give some sort of indication.)

this by no means guarantees it will be okayed by ACX when it comes down to it.

No, it doesn’t. Audacity ACX-Check is a simulation of the tools used by ACX on your submission and as we frequently insist, that’s only the first step in submission acceptance.

That’s the automated process that gets you in the front door. We said, hey, if they automated it, we can too.

There are new specifications as of The Sickness. I have to be able to buy your book on Amazon in paper or eBook form, and you can’t be reading a technical manual, meditation background, or cookbook. My fuzzy description is the need to have character, plot, and setting.

There are variations. The Hero’s Journey by Joseph Campbell is a terrific audiobook about someone who describes a character who has plot and setting.

You also have to pass ACX Human Quality Control where a real person listens to the work for good theater and presentation and absence of sound and voice errors. You can fail if you stutter, you have tongue ticks or lip smacks, or your voice scares the horses.


I don’t expect those noise numbers to cause problems—with reservations. Again, my fuzzy concept is even though the ACX noise limit is -60dB (background noise a thousand times quieter than your voice), you have to pass by at least -65dB in Real Life.

You do. But it can depend a great deal on what the noise is. Nobody cares about spring rain in the trees shshshshshsh “pink noise” sounds, but some microphone and computer combinations have Frying Mosquito sounds that are audible to most people and annoying even if they’re quieter than the specification. So you have to do some analysis.

Why did the noise increase in those two louder than normal chapters? What is it? Open a copy of the chapter in Audacity, drag-select a portion of the Room Tone you have at the beginning or end of the chapter and Effect > Amplify > OK. That will artificially boost the volume of the noise so it’s easier to hear. Does the noise have a signature? Is it jets going over? Your refrigerator? That’s probably not good. If it’s generic traffic noises that probably OK, but it’s up to ACX as a final word.

The noise can’t change over the course of the chapter and you totally can’t have a fire engine or ambulance go by.


Thanks for that, as always. Oh, it’s a novel I’m producing the book for a Real Author, who is selling her stuff on Amazon through kindle and paperback, and has other books of hers up on Audible, so I should be ok on that point, thanks. There do seem to be a lot of scams out there on ACX unfortunately, but I know this isn’t one as I’ve been able to contact the author through her Facebook page, thankfully!

She (the author) likes my voice and cadence, so hopefully shouldn’t be bad enough to scare the horses to other people!

I’m religious about removing lip smacking and other clicks, but usually leaving breathing in if it isn’t intrusive (opinion seems divided on the subject of how much should be taken out!)

The increased background noise is in the ones I did during the day rather than the night - I actually can’t make out any particular thing adding to it, I think it’s just there being more vague ambient noise in the daytime, but not really clear enough for me to actually make out anything. Hopefully that’s a good thing.

I do each chapter at the same time, as it were - in one sitting, so such things don’t change within the chapter itself. I was worried if the change between chapters might not be acceptable, even though I really can’t tell any difference between them myself.

shouldn’t be bad enough to scare the horses to other people!

Your client and ACX count. Others, not so much. It’s up to the client to judge whether the book is going to be a run-away success. ACX wants something they can sell to everybody on earth.

opinion seems divided on the subject of how much [breathing] should be taken out!

ACX gave new readers a weenie (technical term) when they stopped allowing you to submit a test chapter. They were still doing that when I failed my submission test. Now, the choices are submit the whole book…or not. I have no facts here, but if I had to guess at it, they did that to shoo people away. As of The Sickness, reading audiobooks became the go-to method of making some cash at home with a simple microphone and your computer. So billions of people did it…or tried to. ACX went underwater with the increased workload plus people calling in sick.

ACX has said they hate distractions. So, my guess is if the breathing is part of the theater (He gasped in horror!), it’s probably OK. Someone posted on the forum a while ago who was clinically asthmatic. That’s not OK.

I think it’s just there being more vague ambient noise in the daytime

The values slosh between the high 60s and low 70s, so it looks like a vast difference, but it’s only 3dB which most people have trouble hearing. Don’t go Diving For Noise. It’s a new user error to get to a stretch of background noise and crank the speaker volume up as far as it will go. That’s not valid. The noise value was chosen so the average listener can ignore it in normal listening which is the same reason the broadcasters chose it.


Great advice. Thank you.