ABSTRACT
One discovery in recent years for those working in acoustics research has been that for physical changes to be perceived subjectively they must be substantial. Small patches of acoustic absorbent or changes in orientation of small surfaces generally have no significant effects. Acoustic character is more a question of gross shape than small detail. This means that, for variable acoustics to be meaningful, major changes are required. This is certainly
the case with variable reverberation time, which often proves to be the most valuable acoustic change one can achieve.
