An Insight into the Influence of Geometrical Features of Rooms on their Acoustic Response Based on Free Path Length Distribution
Previous research has shown that the geometric shape of rooms distinctly affects their acoustic response, particularly the reverberation time. These findings, however, are not accompanied by a proper theory that helps predict the phenomenon. This paper presents an analysis of the influence
of room geometry on the reverberation time. The concept of room geometry in this paper includes two levels: the room shape (geometry at "macro level") and geometrical structures affecting scattering at room surfaces (geometry at "micro level"). The analysis has been carried out using a database
containing software models of 52 different rooms. The rooms have been selected to cover a wide variety of shapes, from simple geometrical forms to real rooms, such as concert halls, churches and sports venues, with their complex volumes. Reverberation time values for all 52 room models were
calculated using the ray-tracing method. Under the circumstances of low absorption (α = 0.1) the results show that the geometrical properties of the rooms noticeably affect their reverberation process. The analysis of the reverberation time reveals that four categories of room
geometrical shape can be recognised, according to their response to the variation of scattering coefficient. Further examination has shown that all the rooms in each group have similar characteristics of free path length distribution (FPL), although these distributions are different from the
other groups. Based on these findings, it was concluded that the shape of the FPL distribution curve should be used as additional data in the prediction of acoustic response of rooms with different geometric shapes and scattering. It was also found that higher moments of the distribution can
be used as a numerical predictor.
Document Type: Research Article
Publication date: 01 November 2007
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