Normalisation of different length signals I have a collection of audio files of subjects sleeping, which have different lengths,  ranging from 8 hours to 10 hours. 

I want to detect when a snore occurs in them.  First of all I want to normalise them.  What is the best method to normalise them so they all have similar values. 

Currently I'm am using the following code which basically sets the sum of all the values to 1. 

recording = recording / norm(recording, 1);


However, for example, the energy value of a snore differs greatly from one recording to another.

Is there any better methods of normalization which will cope with a range of different length recordings?
In audio, "normalization" means making all values be between 0 and 1. So

recording = recording / max( abs(min(recording)), abs(max(recording)) );