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  • Author: Krzysztof Brawata x
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Tadeusz Kamisiński, Krzysztof Brawata, Adam Pilch, Jarosław Rubacha and Marcin Zastawnik

Abstract

The paper focuses on the problem of test signal selection in determining the sound scattering coefficient in accordance with ISO 17497-1. Research shows that the use of MLS signal is preferred in this procedure. The sine sweep signal, despite its advantages, presents certain limitations if the sample is moving during measurement. An attempt has been made to develop a method that allows for minimization of error, demonstrating the dependence of the obtained values of the sound scattering coefficient on the rotational speed of the turntable and type of test signal. Conditions for the application of the sine sweep signals in continuous and discrete measurements were defined.

Open access

Tadeusz Kamisiński, Krzysztof Brawata, Adam Pilch, Jarosław Rubacha and Marcin Zastawnik

Abstract

Fabric covering is often used by designers, as it can easily mask acoustic structures that do not match an interior. However, in the case of sound diffusers based on change in the phase of the reflected wave, the use of fabric covering is not without its effect on acoustics. It reduces the effectiveness of these structures and raises acoustic absorption. In the paper, the authors analyzed the acoustical properties of a selected fabric used to cover sound diffusers. Sound absorption and scattering coefficients for a system composed of sound diffusers and a fabric situated at different distances d were measured. The results were compared to the sound absorption predicted on the basis of Kuttruff’s and Mechel’s theoretical models. Analysis of the results indicates that the fabric has a significant influence on the system’s acoustic parameters. It is also observed, that fabric applied directly on a phase grating diffuser, produces higher absorption than when it is at some distance from it.

Open access

Anna Sygulska and Krzysztof Brawata

Abstract

The paper describes issues of the proscenium area shown on the example of two opera houses. The subject of the analysis was the design of the Chamber Opera House in Kalisz and the already existing building of the Opera House in Krakow. It covers the influence of the proscenium walls and forestage ceiling on the acoustic conditions in the auditorium. Another subject of the investigation was the influence of the primary proscenium, designed in the very first opera houses in Baroque. The analyses were carried out by means of two computer softwares: Ray Model and Catt Acoustic, and such parameters as sound strength (G), reverberation time (RT), early decay time (EDT), C80 (clarity) index and center time (TS) were calculated. The parameters were further analyzed in the auditorium for three positions of the sound source on the stage.