How to keep volume level the same for all chapters?

Special Interest Groups Audiobook Production
1

I’m doing an audio book and this is all new to me, so I’m trying to figure it all out and have it turn out as professional as possible. When listening back, each chapter sounds at a different volume. When I just select Effect/Amplify, the numbers in the box for Amplification are all different- one as low as 13.759 and one as high as 20.062.

Since I have to stay in the range of these requirements- (Each uploaded file must measure between -23dB and -18dB RMS.
Each uploaded file must have peak values no higher than -3dB. Each uploaded file must have a noise floor no higher than -60dB RMS.) how do I increase the volume of each chapter and stay within these ranges? Where do you “check” to see if you are in those limits?

I notice if I move the slider to increase, then different numbers appear in the New Peak Amplitude box. Should I be concerned about those numbers?

Also, how do you listen back to hear your increased volume? I read that if you check the box “allow clipping,” it distorts the sound, yet it seems you have to check that, just to hear playback.

Thanks in advance for any help with this.

2

Audacity publishes Audiobook Mastering which is a suite of three tools that guarantee RMS (loudness) and Peak. If you recorded well in a quiet, echo-free room, that may be all you need.

https://wiki.audacityteam.org/wiki/Audiobook_Mastering

That’s the encyclopedic version. This is the short version if you’re familiar with the Audacity tools.

We also publish ACX Check which is a cousin to the testing that ACX does. We also check noise, and I don’t think ACX does that.

https://wiki.audacityteam.org/wiki/Nyquist_Analyze_Plug-ins#ACX_Check

This is what it looks like when you succeed.




There are two items good to know when you decide to read for audiobooks. I have to be able to buy your book in either paper or eBook on Amazon right now, and your book can’t be on the forbidden list (scroll down).

https://www.acx.com/help/200878270

You can’t read a cookbook.

And finally, your reading has to be theatrically perfect. You can’t have recordings with wild volume swings and you can’t have mouth noises or other speech problems. The ACX ideal is listening to someone telling you a fascinating story over cups of tea. If your voice scares the horses, you may not be a good candidate.

You can post a short voice sample to the forum.

https://www.kozco.com/tech/audacity/TestClip/Record_A_Clip.html

Koz

3

I recommend you buy and listen to an audiobook. I have several by my favorite author Sarah Vowell. It’s one thing to read about all the specifications and rules, and another to actually hear them in action.

ACX has the Audiolab Service.

https://www.acx.com/audiolab

Please note that to use the service you have an have a bluejeans jacket and no hair.

That service will check for everything possible without human intervention. In other words, the machines can’t do theatrical or presentation checks.

ACX used to offer Human Quality Control where a human would analyze a brief spoken segment and offer comments and suggestions. Not any more. The first time a human sees your work (other than here on the forum) is when you submit the whole book.

We assume this is a result of Covid problems. Their office service collapsed and half the staff called in sick. At that exact instant, everybody on earth decided to read for audiobooks. Not a good combination.

There’s other notes about this process. Recording your voice at home is not as easy as the microphone makers tell you it is.

Koz

4

each chapter sounds at a different volume.

There are tricks for making your recordings come out close to ideal. Live monitoring is good. Many microphones and microphone systems allow you to listen to yourself live in real time. That goes a very long way to getting rid of wild swings in volume. Good quality, sealed against the head headphones are best.

This is an analog microphone with a USB interface that has a place to plug your headphones. Wireless headphones or earphones won’t work for this.

Make sure the Audacity bouncing sound meter has occasional pops up to about -6dB or 50% on the blue waves.

About like this.

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If your blue waves are so tiny you can’t see the wiggles, that’s not loud enough. It’s a good bet you will be having noise problems down the line.

Somewhere in here you should tell us which microphone you are using and describe your studio.

Koz

5

Since I’m new to Audacity and audiobooks, I have had a few problems along the way that I wasn’t aware of. One main problem that occurred and that I didn’t realize until I was almost finished recording my book, is that Audacity has put the microphone volume button in a very bad place. It is just underneath the pause, play and stop buttons, which I used frequently to edit. Just a slight movement of the cursor and a tap and suddenly the recording volume for the mic can be reduced significantly. This must have happened along the way and I noticed when listening back, that it didn’t sound as loud as before and I didn’t know why. (I did not use headphones to listen to myself as I recorded.) I continued on believing I could just raise the level for the volume on these chapters later on.

So, how do I now make all the chapters, at the same volume level, easily?

6

If that was the cause of the low volume, then you can correct it by applying the Amplify effect to the affected audio. See: Amplify - Audacity Manual

7

Audacity has put the microphone volume button in a very bad place.

You don’t have to leave them there. Those little vertical ticked stripes on the left are drag bars. Click and put the tools wherever you want them.

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You can click and put the bouncing sound meters on the desktop and not restrict them to the Audacity work window at all. It’s also possible to change the height and width. From your recent experience, you know how important it is to keep an eye on your volumes.

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It’s not obvious, but the ACX volume specifications are in RMS (Loudness) not peak. So to measure your performance, you should be using Analyze > Contrast or Analyze > ACX-Check, not any of the other tools. This can make Effect > Amplify a little bit of an adventure since it adjusts work in peaks, not RMS.

Post back if you get stuck anywhere.

Koz

8

Thanks for telling me about how to move the tools to a different area! I wish I would have know that in the beginning and then I might have recorded all at the same level, instead of accidentally lowering the mic recording volume because it was under the pause, play and stop buttons.

Now that these chapters are at different volumes, I’m guessing I’m on my own to find a way to make each chapter sound at the same volume. My concern was that if I raise the volume with effect/amplify, that I would distort it or that I wouldn’t be able to match the other chapters volume level and that I stay within the requirements of ACX. Is there a place to just put in a number, like 20 and do that for all the chapters so the volume is all at one sound level?

9

Is there a place to just put in a number, like 20 and do that for all the chapters so the volume is all at one sound level?

You just described Audiobook Mastering. Although I would do it for each chapter rather than the whole book. You still have to deal with editing and error patching and that can create volume problems.

The first tool gets rid of rumble and low pitch sound that might interfere with the other two tools. Many home microphones produce rumble and thunder by accident because it’s expensive to get rid of it, and most people can’t hear it anyway. But rumble can screw up audiobook processing.

The second tool sets the performance volume at -20dB RMS. The last tool gently patches any peaks and tips that might be louder than -3dB.

You only need the first tool, Filter Curve, once per chapter. You can use the other two (in that order) as many times as you want. If they’re not needed, they don’t do anything.

How are you checking that your existing chapters meet ACX specifications? I guess it’s possible to read directly into ACX with no other corrections, but I think you would make the newspapers if you could do that.

We also publish ACX-Check which will tell you all three of the Audiobook quality values. There are very minor differences between Audacity ACX Check and the way the real ACX does it, but in general, if you pass one, you will pass the other. You don’t have to use ACX Check, but if you measure your performance manually using existing tools, it’s pretty painful and time consuming.




One other note. You can mess with volumes and peaks with semi-automated tools, microphone spacing, etc, but home readers never pass noise. In English, -60dB means your background noise when you stop talking has to be at least a thousand times quieter than your voice. That’s almost impossible for most homes. The only reason I can do it is one of the former owners of the house soundproofed the bedroom.

I also published a sound clip I shot in my garage after dark and that came out pretty well.

Koz

10

There are a couple of file format notes.

I’m perfectly clear that ACX wants submissions to be in 192 quality (minimum), Constant Mode, MP3. But you should not be producing your chapters like that.

Export your chapter, read-through errors and all, as a WAV sound file. Only then save it as an Audacity Project for editing. If something nasty happens to the Project, you can open up a copy of the chapter’s WAV and continue on.

Same with the chapter’s final Edit Master. Export a WAV first, and then an Audacity Project, and then prepare the MP3 for submission.

You can’t edit an MP3 file without causing compression and sound damage. For one odd example, say you need to make a change to the submitted MP3. You open it up in Audacity, make the change and export a new MP3 for submission. That Export isn’t 192 quality any more. You have to make corrections to the Edit Master Project or the Edit Master WAV.

WAV files are more robust and resistant to damage than Audacity Projects. It’s not that unusual to open up an Audacity Project and find it will not open and it’s permanently damaged. Many forum posts about this problem.

If this was easy, anybody could do it.

Koz

11

Is there anything wrong with editing in the Audacity project and then saving as a wav file?

12

Is there anything wrong with editing in the Audacity project and then saving as a wav file?

Yes, there is something wrong. Audacity will not Save a WAV file. You have to Export one.

Export your chapter, read-through errors and all, as a WAV sound file. Only then save it as an Audacity Project for editing. If something nasty happens to the Project, you can open up a copy of the chapter’s WAV and continue on.

Same with the chapter’s final Edit Master. Export a WAV first, and then an Audacity Project, and then prepare the MP3 for submission.

Please read that through again carefully. Read your work. Export a WAV and then Save a project for editing. When your editing is done, export a WAV Edit Master file and only then save the final Project.

In both cases you have a perfect quality, stable, backup WAV sound file of valuable work no matter what happens to Audacity or the Project files. If your Project edit goes up in a ball of flame, you have the performance WAV as a backup. If your final Edit Master Project will not open (more common than you think), you have the Edit Master WAV as backup.

13

Did you try any of the Audacity ACX tools?

When you get that far, there are even shortcuts available.

Koz

14

I have somewhat different issue. My friend just completed an audiobook but there were some needed changes. When I attempt to insert the corrected audio, it doesn’t have the same sound as the original file. The processing settings are the same. Every file meets ACX standards as we have sent them through their Audio Lab first. How can I “match” the edits with the original so you can’t tell there is and edit?