Normalisation (or normalization for the Americans), is a very useful tool when mastering or mixing down tracks. As I´ve said earlier, mastering aims to achieve the loudest possible mix without losing too much sound quality. Normalisation helps us achieve this by doing the following. Firstly, it finds the highest peak in a track. Secondly, it raises this highest peak to the loudest it can go (normally 0 dB or 0.3 dB/98 %). And lastly, it raises everything else in the track to a point which is relative to the highest peak. Thus, normalisation creates a louder track without affecting the signal-to-noise ratio [1].

This is how one can normalise tracks in Ardour. If you look in the Edit menu of Ardour, you´ll find a dropdown called Region Operations and inside you´ll find a Normalize Region command. The shortcut for this command is `N´. So select the track you wish to normalise, then simply press `N´. Your track has now been normalised. You might even see the track peaks change a little. I recommend you do this on all your recorded tracks to achieve a louder, more professional mix.

[1] Normalisation Wiki Entry: http://en.wikipedia.org/wiki/Audio_normalization