LIFTERING: WINDOWING CEPSTRAL COEFFICIENTS

• Low order cepstral coefficients are sensitive to spectral slope, glottal pulse shape, etc.
  
  
• High order cepstral coefficients are sensitive to the analysis window position and other temporal artifacts.
  
  
• For speaker independent recognition, it is best to minimize such speaker-dependent variations in the features prior to recognition.
  
  
• We can reduce the variations in these coefficients by using a raised sine window that emphasizes coefficients at the center of the window:
  
• L is the number of cepstral coefficients (typically 24), and G is a constant normally designed to make the energy of the window equal to 1.