Supplements IEC Publication 565 by clause 10: calibration with a pistonphone and clause 11: calibration with a vibrating column. The first method allows a calibration in a simple way inside a chamber partly filled with water, at low frequencies at which the wavelength is large compared with the largest dimensions of the chamber. The second method, using an open column of liquid at low frequencies at which the wavelength is larger than the length of the column, allows a calibration in a simple way. The accuracy of both methods is less than for the method of compensation in a closed chamber, the frequency range of the first is smaller and of the second larger.