def value(self):
        """
        Represents the state of the buzzer as a value between -1 (representing
        the minimum tone) and 1 (representing the maximum tone). This can also
        be the special value :data:`None` indicating that the buzzer is
        currently silent.
        """
        if self.pwm_device.pin.frequency is None:
            return None
        else:
            try:
                return log2(
                    self.pwm_device.pin.frequency / self.mid_tone.frequency
                ) / self.octaves
            except ZeroDivisionError:
                return 0.0