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

def addSpectrogram(self, ydata, fs, title=None):
        """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
        """
        p = SpecWidget()
        p.updateData(ydata, fs)
        if title is not None:
            p.setTitle(title)
        self.stacker.addWidget(p)