Pre-emphasis

• The LP filter so far presented attempts to fit an all-pole model using the least-mean-squares distance metric.
• The lower formants contain more energy and therefore are preferentially modeled with respect to the higher formants
• A pre-emphasis filter,
  
  is often used to boost the higher frequencies. Typically , or the optimal pre-emphasis is used.
• If reconstructing the speech the inverse filter should be used: