def hsll(wnd, res=20, neighbors=2):
  """
  Highest Side Lobe Level (dB).

  Parameters
  ----------
  res :
    Zero-padding factor. 1 for no zero-padding, 2 for twice the length, etc..
  neighbors :
    Number of neighbors needed by ``get_peaks`` to define a peak.
  """
  spectrum = dB20(rfft(wnd, res * len(wnd)))
  first_peak = next(get_peaks(spectrum, neighbors=neighbors))
  return max(spectrum[first_peak:]) - spectrum[0]