I would like to combine a number of .WAV files end-end for analysis.
I add the files as separate tracks and click on Tracks - Align Tracks - Align End to end.
When I export all the files as a single .WAV, the resulting file adds around 10dB amplitude to the original .WAV files?
The volume slider to the left of the waveform changes the volume for monitoring and export without changing the visual waveform. Sometimes it gets accidently moved.
You can quickly check your peak levels by running the Amplify effect. I will default to whatever change is needed for maximized/normalized 0dB peaks. For example, if it defaults to +3dB, your current peaks are -3dB. You can cancel the effect before applying if you just want to check.
You can check before exporting and then open the file and check again. …This won’t tell you anything if the peaks are maxed-out or clipped at 0dB. But if you’re not sure you can Amplify or Normalize for -1dB peaks before exporting. The exported WAV should then be identical.
I would like to combine a number of .WAV files end-end for analysis.
That should be OK but if you “combine” by mixing they are summed together and they will be “louder”.
Thanks for your reply @DVDdoug
I checked that the sliders hadn’t moved for each track.
As the tracks are now arranged end to end, mixing down as one file will sum each track with empty space in the other tracks. So summing should retain the original amplitude?
End to end doesn’t normally change the amplitude. Only when you mix (overlap) like when you mix a vocal and a guitar track together. Or, if they overlap by starting the 2nd one before the 1st one has ended. And in that case you’d only get the “boost” where they overlap.
Yes, that is what is puzzling me why the amplitude is increasing.
There is a reported bug on a previous version of Audacity that did this when creating an MP3 file.
I’m still baffled, but you can export as 32-bit floating-point WAV which essentially has no upper (or lower) limit so it won’t clip/distort.
Then open the floating-point WAV and run the Amplify or Normalize effect to re-adjust the volume to whatever you want at whatever WAV or MP3 settings you want. (If you enter a negative dB value into the Amplify effect it will attenuate rather than amplify.)
MP3 (lossy “imperfect” compression) sometimes ends-up boosting the peaks by 1dB or so.
And you said “WAV”.
So I have just taken a single .WAV file and imported it as a track into Audacity. When I export the audio to a .WAV file it adds around 9dB gain to the resulting file?
Hard to believe… How are you measuring that, before and after??
Apologies, we have just discovered that APx500 software (used for analysis) is applying a correction factor to the original WAV file in the header! Copying the same header data to the combined WAV file results in the same amplitude.
Thanks for your patience @DVDdoug 
This has nothing to do with your problem, but I am going to suggest it anyway.
If all you want to do is concatenate a bunch of audio files into one, FFMPEG can do that for you with one command.
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