Evaluación Acústica Objetiva y Subjetiva en Salas y Teatros de Andalucía
- Autores: Pedro Bustamante Rojas
- Localización: Revista de acústica, ISSN-e 0210-3680, Vol. 47, Nº. 1-2, 2016, págs. 56-58
- Idioma: español
- Enlaces
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Resumen
The main objective of the Ph. D. Thesis, developed within the TEP-130 research group of the Andalusian Research, Development and Innovation Research Plan (Plan Andaluz de Investigación, Desarrollo e Innovación), is to characterize the acoustics of the main concert halls in Andalusia. Specifically, nine rooms, theatres and auditoriums of the autonomous region have been analysed. These spaces are currently in use and include a music program in their regular programming. To this end, on-site impulse responses (IRs) have been recorded, by using various positions of the sound source on the stage, and by distributing microphone positions in the audience area. Omnidirectional microphones, with figure-of-eight directivity and binaural torso simulators are used. Acoustic parameters, which characterize and assess the sound field of the enclosures, are obtained from these IRs. In spaces equipped with an orchestra shell, the IRs have been obtained and analyzed for the two configurations: with and without the aforementioned equipment installed.
The sound field in each hall has been characterized by providing and analyzing the average of the spectral behaviour of each of the acoustic parameters and by assessing its spatial dispersion for each octave band of interest.
Likewise, the spectral average values of qualification have been calculated, by also characterizing their spatial dispersion in terms of the respective Just Noticeable Differences (JND).
The effect of the shell on the behaviour of the acoustic field has been assessed in the audience area, thereby revealing that its presence produces slight changes in reverberation parameters, slight decreases in warmth, musical clarity and definition, and, overall, that it increases the sound strength (2 JND), the lateral energy fraction (about 6 JND) and late lateral sound level (2 dB) in each hall.
In the case of the Maestranza theatre of Seville, due to its multi-configurable character, further analysis has been carried out by using simulation techniques for configurations that were impossible to measure. To this end, the calibrated symphony model for the initial configuration used in the on-site measurements is taken as the starting point. From this model, the appropriate changes are made to model the behaviour of the second symphonic and opera configuration. The results of theses analyses have been published in an indexed journal.
Surveys have also been conducted, and analysis of their results, item by item, for each room, has established a graphic procedure that enables a visual comparison of results. These surveys also demonstrate that the auditoriums (Manuel de Falla in Granada and Maestranza Theatre in Seville) deserve the best ratings in all aspects surveyed, both by experts and by the public attending concerts. After both individual objective characterization (through acoustic parameters) and individual perceptive characterization (with survey results), a global analysis is performed and the relationship between the results of the acoustic parameters and several aspects of the sensation perceived by respondents are researched. In this context, measured values are compared with those provided in each case by the revised Barron model, revealing that the model is able to predict, in general, those measured values of the parameters that present a variation with source-receiver distance (C80, D50, G, and Ts ) with acceptable accuracy (+2 JND), especially in the case when the orchestra shell is installed. The Beranek qualification indices for each hall have been obtained, and it has become evident that the two aforementioned auditoriums and the Villamarta theatre of Jerez achieve the highest rating. In this whole analysis, particular attention has been paid to parameters related to the perceived spatial impression (JLFm, JLLFm, LJm, IACCEm, IACCLm). Since these parameters show no clear dependence on source-receiver distance, the possible dependence on distance relative to the axis of the enclosure has been investigated, and conclusions of interest in this regard have been drawn. Dependence on the variance of the position of the source on the stage and on the presence or absence of the orchestra shell has also been studied. This analysis has been published in an indexed journal.
Finally, indicative relationships between the results of the objective parameters and the valuations of the corresponding items of the surveys have been analyzed and established, although some of the predicted relationships have not appeared.
The conclusions drawn, in addition to the interest that can contribute towards the advancement of knowledge, also promise to be useful for architects of concert halls, inasmuch for new design as for renovation and rehabilitation.
We have striven to provide professional architects with a broader knowledge of the acoustic behaviour of these spaces, by providing data and appropriate tools to undertake architectural projects of cultural spaces. In addition, it is worth underlining the contribution that this work involves in the sense of broadening the concept of architectural heritage, including the aspects of sound as part of the intangible heritage associated with these spaces, which have been specially designed for the communication of sound.
