def amplitude(self, caldb, calv, atten=0):
        """Calculates the voltage amplitude for this stimulus, using
        internal intensity value and the given reference intensity & voltage

        :param caldb: calibration intensity in dbSPL
        :type caldb: float
        :param calv: calibration voltage that was used to record the intensity provided
        :type calv: float
        """
        amp = (10 ** (float(self._intensity+atten-caldb)/20)*calv)
        return amp