"Normalize" discrepancy

[Aroha]

From the manual: Basic recording, editing and exporting, Step 4: Adjusting Amplitude:

Choose Effect > Normalize....
Accept (for now) the default choices in the Normalize dialog and click the OK button
The volume is normalized to -1 dB, so leaving a little headroom below the maximum possible 0 dB level.

From Tutorials > Sample workflow for LP digitisation, Step 17: Amplitude adjustment:
Use Effect > Normalize as the last editing step to bring the amplitude to around -3.0 dB.

Can you please explain this discrepancy? Does it mean that the default is -1dB and should be tweaked up to -3dB?
Or is it a misprint?
If the former, I think the manual should be amended to make it clearer for beginners!

Thanks.

[kozikowski]

-1dB and should be tweaked up to -3dB?

It's down to -3dB. Maximum volume is 0dB sound gets quieter as the numbers increase.

We'll make a note of that.

It's very difficult to hear a 2dB shift in volume, so as a practical matter, you should just be consistent with your work. You are likely to experience far greater volume changes in your transfers simply from different studio music mixing. Taking a Decca record off and putting a Columbia record on. I did some transfers for my sister and I had to chase the volume around between disks.

If you like to listen to audiobooks, one of the sound specifications is peak values no louder than -3dB. So that's a known performance standard.

Koz

[steve]

Does it mean that the default is -1dB and should be tweaked up to -3dB?
Or is it a misprint?

You mean "tweaked down to -3dB".
In both cases the dB level is with reference to "full scale" (maximum, full track height), so in both cases they mean "below 0 dB". That is, a negative dB level.
No it's not a misprint.

From the manual: Basic recording, editing and exporting, Step 4: Adjusting Amplitude:

You mean this? http://manual.audacityteam.org/man/basi ... rting.html

The volume is normalized to -1 dB, so leaving a little headroom below the maximum possible 0 dB level.

Yes it says that.

From Tutorials > Sample workflow for LP digitisation

This? http://manual.audacityteam.org/man/samp ... ation.html

Use Effect > Normalize as the last editing step to bring the amplitude to around -3.0 dB.

Yes it says that.

Can you please explain this discrepancy?

There is no discrepancy. They agree that the final step should be to adjust the level to a little under 0 dB.
The point is that it is recommended to leave a bit of headroom. The exact amount of headroom that should be allowed is hotly debated in some quarters,

I generally allow 1 dB headroom. Other argue that 1 dB headroom is not enough to guarantee space for inter-sample peaks. Over the past few years, there has been a growing fashion among "audiophiles" to allow more headroom.

The question is, how big a bit is "a bit" of headroom?
Opinions vary, but most agree that somewhere in the region of -1 to -3 dB for exported files.
It's rather like a recipe that say to add "a pinch of salt" - how much is that in grams?

[Gale Andrews]

From the manual: Basic recording, editing and exporting, Step 4: Adjusting Amplitude:

Choose Effect > Normalize....
Accept (for now) the default choices in the Normalize dialog and click the OK button
The volume is normalized to -1 dB, so leaving a little headroom below the maximum possible 0 dB level.

From Tutorials > Sample workflow for LP digitisation, Step 17: Amplitude adjustment:
Use Effect > Normalize as the last editing step to bring the amplitude to around -3.0 dB.

Can you please explain this discrepancy?

Perhaps the problem is that the Workflows are not clear enough that the -3 dB is a user-modifiable setting.

I've made that clearer in both Workflows for the next (2.1.3) release of Audacity, when that comes out.


Gale

[kozikowski]

Or the more modern "adjust seasoning to taste."

1dB can get you into trouble if you produce highly compressed MP3 versions for your Personal Music Player. That compression can soak up your 1dB safety zone leaving no protection.

Koz

[Aroha]

Thanks everyone for your posts.

Gale, I'll look forward to the next version.