On 13.04.2021 we were at the test centre of the TU Berlin and calibrated our own IRIS kits for the measurement of the strength measure according to DIN EN ISO 3382-1 and the level-dependent quantities according to DIN EN ISO 3382-3. Out of curiosity, we carried out the measurements according to the diffuse field method in the reverberation room as well as according to the free field method in the anechoic room…the level differences are about 1 dB.