--- Some changes on the Lectures 2 and 3 slides ---
Slide 26 "Mel-Filter Bank":
   In the figure, the symbols used for mel-scale power spectrum
   have been changed to improve consistency.   (on 25/Jan.)

Slide 38 "Feature Normalisation": 
   In the formula for CMN/CVN, symbols have been updated to improve
   consistency and to avoid confusions.   (on 25/Jan.)