Zero Level Detector to cut out silence or pauses in a signal?

I have a speech signal and I want to clear any pauses in it so I have the same size frames when I am comparing it in my database.

I am using MFCC as my feature extraction and also will be using PLP to compare, therefore when comparing signals there cannot be any pauses or silence or else there will be errors.

Does anyone know any code or ways of deleting anything below 0 (silence) or use a simple If else statements?

Thanks