Normalize

Use the Normalize effect to set the maximum amplitude of single or multiple tracks, equalize the peak volumes of the left and right channels of stereo tracks and optionally remove any DC offset from the tracks.

Accessed by: Effect > Normalize...

Normalize works independently on left and right channels of a stereo track. This is useful for correcting stereo recordings of LPs and cassettes which can often be unbalanced, as long as significant clicks are removed first. To normalize an individual stereo track without affecting its channel balance, use the Amplify effect.

For a full discussion of the differences between the Amplify and Normalize effects, see this page on the wiki.

Remove any DC offset

When this box is checked Normalize will attempt to remove any DC offset in the selection by finding the average of all the sample values in the selection, then subtracting that average value from all the samples. This works well on long selections containing a mix of sounds, but may actually create DC offset when applied to short sections of recordings of voices or certain instruments that have an inherently asymmetrical waveform.

Normalize Maximum Amplitude to

Enter the value for the maximum amplitude you would like the processed selection to have. Normalize defaults to 0.0 dB, which is the maximum amplitude possible without clipping. Entered values are negative; you cannot enter positive values.

Difference from the Amplify effect

Normalize processes the left and right channels of a stereo track independently. Amplify applies the same amplification to both channels.

Normalize will not let you create clipping. Amplify will let you create clipping.

Normalize offers the option to remove DC offset. Amplify does not offer this option.

For a more thorough discussion of differences between the Amplify and Normalize effects, see this page in the Audacity wiki