Error factors in the measurement of the scattering coefficient in full and small scales

Abstract

The reverberation room method for measuring the random-incidence scattering coefficient was standardized by ISO 17497-1 in 2004, and now the amendment is being discussed on the specimen mounting and the turntable speed. Regarding the former point, destructive diffraction from an uneven perimeter of a specimen is an error factor to overestimate the scattering coefficient; however, it can be suppressed by setting a border around the turntable. Regarding the latter point, special attention is needed to the combination of the turntable speed and the signal period of MLS in the impulse response measurement. Basically, the turntable speed should be limited by an angular step of 3° to 6° for one signal, thus 60 to 120 signals are required for one revolution. In practice, in order to suppress the time variance, a shorter signal period is preferred as far as the measured reverberation time is guaranteed. However, a best choice of the signal period depends on reverberation rooms in full and small scales, additional...