sentences:  As a time-frequency representation, the spectrogram has
  relatively poor resolution.Time and frequency resolution
  are governed by the choice of analysis window and greater
  concentration in one domain is accompanied by greater
  smearing in the other.A time-frequency representation having improved resolution,
  relative to the spectrogram, is the Wigner–Ville distribution, 
  which may be interpreted as a short-time
  Fourier transform with a window function that is perfectly
  matched to the signal.