Acoustical Criteria for Auditoriums and Their Relation to Model Techniques

The first step in using model technique as a design tool is to establish a quantitative criterion (besides reverberation time). “Early to reverberant energy,” “steepness,” and “initial reverberation time” or “early decay time” (EDT) must be considered the most relevant factors, from aspects such as: (1) simplicity of measurement, (2) correlation with subjective assessments, and (3) possibility of comparing values obtained in scaled models with values obtained in full-size halls. Measured values of EDT may be applied either by calculating the inversion index, i.e., the average value in the audience area of a hall divided by the average value in the stage area, or by comparing values of EDT measured in different locations of a model (or a hall) with values of average reverberation time. These techniques have been applied in a number of 1:10 scale models and, also, in some completed halls.