Variability of acoustic parameters over audience areas in auditoria

Abstract

Besides Reverberation Time, recently other quantities have been used to characterize sound fields inside Concert Halls, Auditoriums, Theatres or Opera Halls. Also known as Acoustical Attributes, these parameters can determine the difference between "good" or "excellent" acoustics. As an example, such parameters can also explain why two concert halls with the same Reverberation Time can be ranked differently. Unlike the "almost" uniform Reverberation Time value, the Acoustical Parameters show a different behaviour thorough the audience area due to its fine structure. This can be observed even in modern Acoustic Simulation software where a parameter value may change from seat to seat, row to row and so on. Nevertheless, some researches tend to represent by a single number the paramters's values obtained from a whole audience area. Nowadays, some measuring procedures imply just a few measuring positions. This fact could yield to not so accurate results when the description of acoustic parameter behaviour is attempted. The aim of this work is to describe the variability of some of the most important acoustic parameters in audience areas by measuring in a large amount of positions inside some real auditoria. The following text is divided in three parts: The Theoretical Background, the description of Measurements in Auditoria and the presentation of Results and Conclusions. The first part gives an introduction to the theory behind the Acoustical Parameters from its Room Acoustic basis, the structure of such quantities, the factors that may influence the values and finally to the most used and recommended values. The second part of this work describes the measures done inside different auditoria in Spain. Finally, the third part presents the obtained results and its inpterpretation according to the theory introduced in the first part of this text.