Some issues in measurement of the random-incidence scattering coefficients in a reverberation room

The present work tries to investigate the problems and uncertainties of measuring random-incidence scattering coefficients in a reverberation room based on ISO 17497-1. A 1:5 scale model of the reverberation room, which has a volume of 2.4 m³, was employed to measure the random-incidence scattering coefficient for periodic battens. In the present work, three factors, the turntable diameter, the air gap below the turntable and the absorption of test sample were considered. The influence of each factor on the scattering coefficients was measured and analysed. It was found that the turntable diameter influenced the scattering coefficient of the baseplate at frequency bands, 1 kHz to 5 kHz, although the values are within the ranges specified in the ISO standard. An air gap of 50 mm below the turntable results in a high scattering coefficient for the base plate and in a low scattering coefficient for the periodic battens at 1 kHz to 5 kHz. Varying the absorption of the test sample has no significant effect on the scattering coefficients.