code: def addSpectrogram(self, ydata, fs, title=None):
          
          p = SpecWidget()
          p.updateData(ydata, fs)
          if title is not None:
              p.setTitle(title)
          self.stacker.addWidget(p)
docs: Adds a new spectorgram plot for the given image. Generates a SpecWidget
  
          :param ydata: 2-D array of the image to display
          :type ydata: numpy.ndarray
          :param fs: the samplerate of the signal in the image, used to set time/ frequency scale
          :type fs: int
          :param title: Plot title
          :type title: str