Abstract
The correct acoustic design of rooms such as classrooms, conference rooms and offices is of fundamental importance to ensure high speech intelligibility and to contain internal noise levels. The use of sound-absorbing ceilings alone is not always sufficient to guarantee adequate comfort, as the reflections between parallel walls could introduce unwanted phenomena such as flutter echo or the accentuation of modal resonances. One more issue is related to the use of Sabine or Eyring models, which could lead to an underestimation of the reverberation times. This article compares the reverberation time measured and simulated in two small rooms with (i) Sabine and Eyring models, (ii) two commercial simulation software and (iii) the EN 12354-6 standard method valid for rooms, with absorption not homogeneously distributed between the surfaces.