ADAPTIVE TECHNIQUES - MINIMIZING MISMATCH

• We can improve recognition performance by training on a single speaker. This is known as speaker dependent speech recognition.
  
  
• However, there are numerous training problems (long enrollment). An alternate approach is to adapt speaker independent models.
  
  
• Such adaptation techniques are generally used to reduce mismatch between the acoustic models and the decoding environment (e.g., microphone, acoustic channel and speaker mismatch).
  
  
• There are two basic approaches:
  
  
  • Maximum A Posteriori (MAP): choosing an estimate that maximizes the posterior probability (consistent with the observed data and prior inormation).
    
    
  • Maximum Likelihood Linear Regression (MLLR): ML estimate of a linear transformation.