sentences:  The method of reassignment smooths the Wigner–Ville
  distribution, but then refocuses the distribution back to
  the true regions of support of the signal components.The
  method has been shown to reduce time and frequency smearing
  of any member of Cohen's class 
  
  .In the case of the reassigned
  spectrogram, the short-time phase spectrum is used to
  correct the nominal time and frequency coordinates of the
  spectral data, and map it back nearer to the true regions of
  support of the analyzed signal.