title: Pre-emphasis in speech processing using android
body: <p>I'm working on an application where i need to implement Mel Frequency Cepstral Coefficients (MFCC) for speech recognition.</p>
  
  <p>The first step in MFCC is to apply Pre-Emphasis</p>
  
  <p>Pre-Emphasis will increase the energy of signal at higher frequency.
  Because the low frequency band is occupied by sounds which are useless/harmful for speech recognition.</p>
  
  <p>I found this equation for this process:</p>
  
  <pre><code> Y[n]=X[n]−0.95⋅X[n−1]
  </code></pre>
  
  <p>My question is should i just simply apply this equation on the original signal?? So that it would increase the energy of the signal at higher frequency. Or should i apply a certain filter on the input signal before applying this equation? and if so, how would i program it?</p>