Abstract:
Speech intelligibility is a major concern in lecture hall acoustical design. Diverse lecture hall geometric configurations exist varying from the classical rectangle to the octagon-shaped plan. This study investigates the acoustical performance of commonly built forms of lecture halls using room acoustic analysis techniques. Simulation of sound fields of ten simple forms is conducted for different volumes and same level of occupancy.
The purpose is to identify the impact of the hall geometry on its acoustics, particularly on the spatial distribution patterns and levels of speech sound in the absence of sound reinforcement systems. Different acoustical parameters from the literature including Loudness, diffusion uniformity, reverberation energy and acoustical defects according to the preferred parameters suggested by (Kurtuff,Mehta).These parameters were quantified and compared to characterize acoustic merits, dissimilarities and overall performance. Insignificant differences were found. Of all the shapes, the fan shaped and the polygons in general had the highest acoustic performance while the Deep rectangle possesses the least merits.
For all shapes, ray diagrams in each section model confirmed that strong early sound reflections from the ceiling were a very important element for providing optimum speech intelligibility. Such investigation is expected to help architects to understand better the effect of early architectural design decisions with respect to form on lecture hall acoustics.
