“Normalize” effect is an effect that sets the maximum amplitude to a chosen level (expressed in decibels). For multiple tracks, “normalize” effect treats each track independently, that is, it will set the maximum amplitude of each track to the chosen level.
An example of this use is my recording of instructional videos. I record instructions or explanations that go with slide displays, and I record the sound for each slide separately and keep the audio for each slide in separate tracks. After all recording is done, I edit the audio using Audacity. If I need to adjust the volume to a certain level, I will want the whole audio to have more or less the same volume even if I happen to speak louder or softer during the recording of each track.
So the behavior of “normalize” to adjust each track independently works very well in this situation.1 But how about a stereo track? Will each channel be adjusted independently, or will both channels be adjusted together and thus preserving the original balance? It turns out that Audacity can do both!
If we think about real applications, we can see that both types of adjustments are needed depending on specific situations. If the recording is of your voice, chances are you want to adjust both channels independently so that the final result will be balanced.2 If you are recording musical instruments, however, it is more likely that you want to preserve the stereo balance to preserve the effect of placement of each instrument in a studio.3
If the option “normalize stereo channels independently” is checked, Audacity will normalize each channel independently, that is, stereo balance will not be preserverd. If the option is unchecked, the opposite is true, that is, stereo balance will be preserved.
I think this option is pretty straightforward and self-explanatory, so I am not using any visual example here. If you have any question, however, feel free to ask it in the comment area.
- For situation where you need to preserve relative balance among tracks, you can use “amplify” instead of “normalize” effect. ↩
- unless you deliberately want the effect of someone speaking from one side of the audience. ↩
- Music creation software even gives you ability to pan each instrument so that each instrument sounds like it is on the left or right side of the room. ↩