A measurement of the measured sound pressure level, as a
        percent. Uses A-weighting, which focuses on levels up to 55 dB.

def sound_pressure_low(self):
        """
        A measurement of the measured sound pressure level, as a
        percent. Uses A-weighting, which focuses on levels up to 55 dB.
        """
        self._ensure_mode(self.MODE_DBA)
        return self.value(0) * self._scale('DBA')