Critical listening tests conducted in full-scale reverberation chambers utilized in the recording industry reveal that there are often two major faults present in the decay of sound in the frequency range below 1000 Hz: (1) prolonged decay of certain axial modes resulting in a characteristic tone imparted to program materials; (2) beating between the modes resulting in a modulation of program material. Scale-model measurements allow the physical factors behind these faults to be isolated quickly. In addition, the model measurements provide a means of minimizing these faults through the optimal selection of room proportions and shape. The experimental technique is described and some preliminary tape-recorded results comparing the decay of pulsed and steady-state sources are presented for scale-model and full-scale chambers.