Llibrivox newbie

I’ve just finished recording and editing my first audio recording for Librivox. I was told that my volume was still to high. I was instructed to use the “amplify” feature in “effects” and enter a negative number (-3) and it would reduce the volume. I did that but it wasn’t reduced enough.

If I knew how to find the decibel level, I would reduce or amplify the file on my own, before submitting it. I’ve looked through help menus in audacity and in librivox but I can’t find how to set the decibel levels or to check them after I’ve finished recording. It’s probably some simple thing I’ve overlooked in my panicked search. Any pointers?


Librivox specify “around 89 dB”, which means normalizing to -7dB in Audacity …
Normalize to -7bB in Audacity.png

Thanks. Is there anyway to see what the dB level is? I get the feeling the person who is proofing my file has a way to do that. She told me my file was at 92.4 dB.

I really appreciate your help. I really am a newbie. The only other sound editinig I’ve ever done was on a tape recorder. We had to cut the tape and use a type of scotch tape to paste it back together.

I found the program I am supposed to use to check the Decibel Levels. It is called Checker. I thought I downloaded it and installed it, but it needed Java and that won’t work in chrome. then I downloaded the wrong version. I thought the 32 or 64 bit referred to the computer and it was the browser. Long story short, thanks for the help with setting the normalize numbers. If I do that and then use checker, I won’t have to keep doing multiple edits after I submit my file. Now I can do multiple edits BEFORE I submitt my file.


We have analysis tools to tell you everything you’ve ever wanted to know about your ACX AudioBook submission, but almost nothing for Librivox. Do they have a page with expected audio values? When you get Checker to work, can you send us a screen capture?

ACX checks for three things: loudness, noise when you stop talking and digital (peak) overload. You definitely have to pass all three before you submit or they will bounce you.

Librivox was always a mystery because nobody posted there enough to generate tools and help.


Checker needs JAVA to work?

JAVA runtime is a known security hazard.

Run away…


My interpretation of the librivox instructions is that the peak volume should never exceed -7dB.
[ Using peak values isn’t a reliable way of getting a measure of volume :
the recording could have one momentary loud click which would skew the result ].

If you use Audacity’s amplify tool it will show a number which is the peak loudness , in this case (-)2dB …
Using ''Amplify'' to normalize to -7dB'.gif
Subtract that number from 96 gives the value librivox are using,
In this case 96-2=94, which needs -5 to make peak volume the specified 89.

You may benefit from applying dynamic-range-compression,which reduces variations in volume …
Demo of ''compress & dynamics' in Audacity'.gif

Here is the page they refer us to. On another page, they tell us to use Checker to check dB levels.

tovarisch” on librivox isn’t obeying the -7dB rule …
Librivox's ''tovarisch'' has peak audio of 2-454.png
His RMS volume value is ~21dB …
Librivox's ''tovarisch'' has RMS audio of ~21dB.png
The RMS value is a more accurate measure of the overall volume : it’s like an average value, rather than a peak value.

Having now looked/listened at/to a few Librivox recordings,
the target to aim for is RMS in the range 21dB-22dB , with peak in the range 2dB-3dB.

Here is the page they refer us to.

Interesting idea. Record a test and play it back. If you have to adjust your computer’s volume control up, then it’s too low. No mention of Audacity’s volume meters or size of the blue waves.

I also notice although they didn’t say so, a USB microphone is assumed.

It’s been our experience that recording cold with a USB microphone always produces a low volume track. So you will always be adjusting your work up, and yes, as above, any sharp, loud sound anywhere in the track is enough to throw everything off. Normal volume tools all work from loud peaks which is why we stopped using them.

I didn’t make it through the whole thing, but I didn’t see any mention of background noise at all. Background hiss and USB microphone noise just kills audiobook readings.

You can use the plain Amplify tool to set the -7dB peaks (89 in Librivox-speak), and that tool will also tell you where your peaks are now to give you an idea of how you’re reading. They all work down from zero being overload, not up from 96 maximum silence.


the target to aim for is RMS in the range 21dB-22dB , with peak in the range 2dB-3dB.

Remarkably similar to the ACX values of peaks no louder than -3 and volume in the -18 to -23 range.

I wonder if Libravox applies processing. That would mean all the reader had to do is get in the ballpark, not hit the specification exactly.


There is some variation in the Librivox recordings, (e.g. this is wide of the mark),
which is evidence against automation being applied.

Have you heard a Librivox performance with that annoying USB whine?



These are the current tools and process for ACX mastering. You may find it handy instead of juggling with the standard tools.


Steve wrote RMS-Normalize and Flynwill developed ACX-Check. The process sets loudness (RMS) first and then goes over and gently pushes the peaks into alignment. Since Librivox doesn’t seem to care about noise, that may be all you need. The process calls for Limiter and that is a standard Audacity tool.