<p>If your audio has DC offset present, you should use Normalize to correct that offset. </p><p>If you are applying a <a href="macros.html" title="Macros">Macro</a ...

Create a tone with an amplitude 0.5 and a length 30s Shrink the clip by about 0.5s (using time-stretching) Select part of the clip, and apply amplify with default settings.