NONLINEAR FREQUENCY WARPING:
BARK AND MEL SCALES

• Critical Bandwidths: correspond to approximately 1.5 mm spacings along the basilar membrane, suggesting a set of 24 bandpass filters.
  
  
• Critical Band: can be related to a bandpass filter whose frequency response corresponds to the tuning curves of an auditory neurons. A frequency range over which two sounds will sound like they are fusing into one.
  
  
• Bark Scale:
  
  
• Mel Scale:
  
  
• Comparison: filter bank implementations for a typical speech recognizer.
  
  
• Nonlinear Frequency Warping: The Bark scale implies a nonlinear frequency mapping of frequency.