Wyniki wyszukiwania - BazTech

1

Can Historic Interiors with Large Cubature be Turned Acoustically Correct?

Kamisiński T., Kulowski A., Kinasz R.

Archives of Acoustics

|

2016

|

Vol. 41, No. 1

3--14

EN

Historic interiors with large cubature, such as reception, theatrical, and concert halls, need to be renovated periodically if they are to be preserved as cultural heritage for future generations. In such cases it is necessary to maintain appropriate balance between requirements imposed by heritage conservation authorities office which are usually being given a higher priority, applicable safety regulations, and the comfort of use, including good acoustics. The paper is a presentation of architectural interference in three historic interiors with large cubature leading to changes in their acoustic qualities. In two cases, the changes were beneficial to the functional qualities of the halls to satisfaction of the investors carrying out the renovation work. In the third instance, the architectural interference aimed at showing off the monumental valor of the interior resulted in significant degradation of its acoustics. To remedy the situation impairing the functional program of the facility, corrective measures are proposed neutral with respect to its historic character.

2

Test Signal Selection for Determining the Sound Scattering Coefficient in a Reverberation Chamber

Kamisiński T., Brawata K., Pilch A., Rubacha J., Zastawnik M.

Archives of Acoustics

|

2012

|

Vol. 37, No. 4

405-409

EN

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.

3

Sound Diffusers with Fabric Covering

Kamisiński T., Brawata K., Pilch A., Rubacha J., Zastawnik M.

Archives of Acoustics

|

2012

|

Vol. 37, No. 3

317-322

EN

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.

4

Correction of Acoustics in Historic Opera Theatres with the Use of Schroeder Diffuser

Kamisiński T.

Archives of Acoustics

|

2012

|

Vol. 37, No. 3

349-354

EN

The paper deals with the problem of acoustic correction in historic opera theatres with the auditorium layout in the form of a horseshoe with deep underbalcony cavities limited with a semicircular wall surface. Both geometry of the cavities and excessive sound absorption determine acoustic phenomena registered in this area of the hall. The problem has been observed in the Theatre of Opera and Ballet in Lviv, Ukraine, where acoustic tests were carried out, simulation calculations performed, and finally a diffusion panel worked out designed for the rear wall of the underbalcony space. Acoustic measurements carried out after installation of the diffusers revealed favourable changes in the sound strength factor G within the range of medium and high frequencies in the underbalcony and auditorium centre area. By replacing textile tapestry with diffusion panels, a significant reduction of sound absorption was achieved for the frequency range above 1 kHz and an increase of uniformity of acoustic parameters registered in the hall. The method presented in the paper can be applied in historic halls of the similar type as well as contemporary rooms where there is a need for correction of acoustic flaws related to sound focusing or the echo effect.

5

The Effect of Geometrical and Material Modification of Sound Diffusers on Their Acoustic Parameters

Pilch A., Kamisiński T.

Archives of Acoustics

|

2011

|

Vol. 36, No. 4

955-966

EN

Sound diffusers, in particular those based on changes in the phase of the reflected wave (Schroeder diffusers), have recently gained greatly in popularity in acoustics as an effective means to eliminate defects and improve the acoustic performance of interiors. This paper draws attention to a possibility of shaping acoustic parameters of sound diffusers and fundamental errors made in applying diffusers. Also, an often neglected issue of sound absorption by diffusers has been tackled. The presented results of laboratory measurements indicate a great significance of the diffusers' rigidity and geometry on their absorption coefficient at low frequencies. The effect of arrangement of elements on the diffusion coefficient was analysed for two types of elements based on the prime number N = 7.