Ariane 5 rocket produces very high sound pressure levels during launch, what can influence structures located in the fairing. To reduce risk of damage, launch in vacuum conditions is preferred for noise sensitive instruments. In Wide Filed Imager (WFI) project, the main part of the filterwheel assembly is an extremely thin (~240 nm) filter of large area (170×170 mm), very sensitive to noise and vibrations. The aim of this study was to verify numerical calculations results in anechoic measurements. The authors also checked the influence of WFI geometry and sound absorbing material position on sound pressure level (SPL) affecting the filter mounted inside the assembly. Finite element method (FEM) simulations were conducted in order to obtain noise levels in filter position during Ariane 5 rocket launch. The results will be used in designing of WFI filterwheel assembly and endurance of the filter during launch verification.
W przypadku imprez muzycznych w budynkach oraz imprez plenerowych o dużym natężeniu dźwięku pojawia się konieczność oceny wpływu ciśnienia akustycznego na konstrukcję obiektów budowlanych, szczególnie jeśli to są obiekty zabytkowe. Przedstawiono metodykę takiej oceny na przykładzie badań konstrukcji sali koncertowej w budynku Filharmonii Krakowskiej. Podstawą oceny był pomiar ciśnienia akustycznego i analiza naprężeń w elementach konstrukcji.
EN
In the case of musical events in buildings and outdoor events with high noise levels need arises to assess the impact of the sound pressure on the structure of buildings, especially if they are historical objects. The paper presents a methodology for such an assessment study on the example of the structure of the concert hall in the building of the Cracow Philharmonic. The basis of the assessment was to measure the sound pressure and analysis of the stress in structural elements.
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.
The paper presents the new solution to a road acoustic screen consisting of elements which are highly diffusing and simultaneously resistant to weathering, but also characterised by a sound absorption. There is described the comprehensive research of such the road acoustic screen with absorbing and diffusing surface. The study includes screen’s resistance to wind load and snow removal, impact tests and measurements of some acoustic parameters.
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The paper deals with the problem of the acoustic treatment using modern material technology in the modernization of old interiors. On the example of an auditorium with approved acoustics, that was built in 1962 and is located at the Lviv Polytechnic, some important directions in handling this type of object was shown. The acoustic measurements of the room showed, that structures used in the 60s are acoustically proper, but planned renovation should be based on modern technologies.
PL
W artykule podjęto zagadnienia modernizacji wnętrz o uznanej akustyce z użyciem współczesnych materiałów. Jako przykład wybrano przygotowywaną do remontu salę audytoryjną Politechniki Lwowskiej (bud. 1962). Przeprowadzone badania akustyczne wykazały poprawność istniejących rozwiązań, jednak projektowane zmiany muszą opierać się na współczesnych technologiach posiadających odmienne właściwości.
The paper presents the verification of a solution to the narrow sound frequency range problem of flat reflective panels. The analytical, numerical and experimental studies concerned flat panels, panels with curved edges and also semicircular elements. There were compared the characteristics of sound reflected from the studied elements in order to verify which panel will provide effective sound reflection and also scattering in the required band of higher frequencies, i.e. above the upper limit frequency. Based on the conducted analyzes, it was found that among some presented solutions to narrow sound frequency range problem, the array composed of panels with curved edges is the most preferred one. Nevertheless, its reflection characteristic does not meet all of the requirements, therefore, it is necessary to search for another solution of canopy which is effective over a wide frequency range.
This paper presents a mechanical positioning system for a measuring microphone designed for acoustic studies in anechoic and reverberation chambers at the Department of Mechanics and Vibroacoustics, AGH. The results are discussed in the context of mechanical positioning and its impact on the outcome of the execution of individual measurement procedures. Moreover, areas for research were identified and solution concepts shown for further development of the automation of acoustic measurements in different research rooms in order to reduce the human involvement in them.
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.
Reflecting structures placed over the stage in auditoria and concert halls should provide sound reflection in a way that enhances sound emission from the stage without causing acoustic defects in the interior. Model studies conducted by the authors were used to determine the relative level of sound reflection by reflecting structures as a function of frequency for a number of geometric configurations and materials. Analysis of the results allowed drawing conclusions about the effect of modifications of the ceiling over the reflecting panels on the quality of the sound reflected from them. It was shown that modification of the ceiling over the reflecting panels by employing highly sound absorbing materials significantly improved the characteristics of the reflected sound. Also, certain configurations of elements located in the space under the ceiling should be avoided, as the experiments indicated the occurrence of adverse acoustic effects.
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.
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.
W artykule przedstawiono opis historycznego wnętrza Auli Głównej Politechniki Lwowskiej, w której wykonano badania akustyczne według procedur normatywnych. Zestawiono wyniki pomiarów i obliczeń wybranych parametrów akustycznych Auli. Celem badań była ocena warunków akustycznych wnętrza pod kątem wypełnienia funkcji zgodnych z jego przeznaczeniem. Dane przygotowano dla potrzeb sporządzenia opinii na temat możliwości wykonania adaptacji akustycznej Auli. Napotkanym problemem przy adaptacji takich wnętrz są ograniczenia związane z koniecznością zachowania historycznej struktury obiektu.
EN
The paper concerns the Lviv State University Assembly Hall that was subject to standard acoustic measurements. A selection of results and calculations of acoustic parameters is presented. The main goal of the measurements was an evaluation of the hall’s acoustic conditions that are relevant to fulfilling the hall’s function. The results will be used to prepare an opinion on a possible acoustic adaptation of the hall. One of the challenges commonly encountered in such objects is the necessity to preserve their original architectural structure.
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Wielofunkcyjność budowli sakralnych jest naturalną cechą charakteryzującą służebność tych obiektów dla określonej społeczności. Pozaliturgiczne wykorzystanie wnętrz do realizacji muzyki i emisji słowa, wymaga jednak właściwej adaptacji akustycznej. W niniejszym artykule przedstawiono na przykładzie kościoła pw. św. Pawła Apostoła w Bochni częsty problem z akustyką występujący w obiektach sakralnych wybudowanych w ostatnim czterdziestoleciu. Nadmierna pogłosowość wnętrza źle wpływa na zrozumiałość mowy i jakość brzmienia muzyki. Na podstawie wykonanych pomiarów akustycznych wnętrza kościoła oraz wielowariantowych symulacji komputerowych zaproponowano adaptację akustyczną, która może rozwiązać ten problem przy jednoczesnym zachowaniu formy architektonicznej obiektu.
EN
Multifunctionality of sacral buildings is a natural feature of usefulness such objects for specific community. However, extra-liturgical utilization of the interiors for realization of music and speech issue demands a proper acoustics adaptation. A frequent problem with acoustics in sacral objects which were built in the last forty years, on example of the St. Paul Apostle's Church in Bochnia, was shown in the paper. An excessive interior's reverberation influences badly on the speech intelligibility and the music sound quality. On the basis of acoustics investigations performed in church's interior as well as multivariant computer simulations, acoustics adaptation which may solve this problem with preservation of architectural shape of object was proposed.
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W artykule przedstawiono wyniki badań akustycznych i symulacji komputerowych wybranych parametrów auli Politechniki Lwowskiej. Aula posiada nadmierną pogłosowość powodującą utrudnienia w użytkowaniu zgodnym z jej podstawową funkcją. Ze względu na ograniczone możliwości ingerencji w zabytkowy charakter wnętrza przeprowadzono analizę dostępnych środków umożliwiających poprawę zrozumiałości mowy. Przedstawiono kilka wariantów adaptacji akustycznej, pozwalającej na uzyskanie kompromisu pomiędzy akustyką a oryginalnym wystrojem wnętrza.
EN
In paper results of acoustical measurements and numerical simulation of Lviv Polytechnic National University Assembly Hall are presented. Too long reverberation time impedes using it according to its main function. Due to limited possibilities of changes of historical interior's character, analysis of available methods of speech intelligibility improvements were made. Some variants of acoustic treatment is presented, that allow to achieve a compromise between good acoustics and original interior's arrangement.
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.
W drogownictwie ekran akustyczny to naturalna lub sztuczna przeszkoda, ustawiana na drodze pomiędzy źródłem hałasu a punktem odniesienia. Za przeszkodą tą powstaje obszar o zmniejszonym poziomie dźwięku.
The article presents the developed system for automated acoustic measurements taken in an anechoic chamber. Technical and functional parameters of the system fulfil specific work conditions in the anechoic chamber and meet the requirements for acoustic research. The automated programmed positioning of the measurement microphone in relation to the tested object is possible thanks to the special multi-axial manipulator. The developed construction of the system provides minimal influence on the acoustic properties of the anechoic chamber. The article also presents important issues of the introduction and the verification of the system.
PL
Artykuł prezentuje opracowany system do zautomatyzowanych pomiarów akustycznych prowadzonych w komorze bezechowej. Parametry techniczne i funkcjonalne systemu odpowiadają specyficznym warunkom pracy w komorze bezechowej i wysokim wymaganiom dla badań akustycznych. Automatyczne zaprogramowane pozycjonowanie mikrofonu pomiarowego względem badanego obiektu umożliwia specjalny manipulator wieloosiowy. Opracowana konstrukcja systemu zapewnia minimalny wpływ na własności akustyczne komory bezechowej. W artykule przedstawiono także istotne problemy procesu wdrożenia i weryfikacji systemu.
Sound reflecting panels are commonly used in concert and conference halls in order to transmit reflected sound to the audience and improve hearing conditions among musicians. The main problem is to design these elements properly. In this paper, the frequency limits of a useful sound transmission range and the efficiency of reflecting structures are theoretically estimated and experimentally verified.
PL
Panele refleksyjne są powszechnie stosowane w salach koncertowych i audytoryjnych. Głównym ich zadaniem jest przekazywanie odbitego dźwięku w kierunku publiczności oraz poprawa słyszalności pomiędzy muzykami na scenie. Odpowiednie zaprojektowanie takich struktur jest jednak bardzo skomplikowane i czasochłonne. W artykule porównano otrzymane doświadczalnie wartości wybranych parametrów akustycznych struktur refleksyjnych z wartościami wyznaczonymi z teoretycznych wzorów.
W pracy omówiono akustyczne aspekty wykorzystania kościoła pod wezwaniem Św. Marii Magdaelny we Lwowie do celów koncertowych. Przedstawiono wyniki pomiarów akustycznych oraz koncepcję poprawy jego walorów akustycznych jako sali koncertowej z wykorzystaniem doraźnie wstawianych do wnętrza elementów, rozpraszających dźwięk i poprawiających wzajemne słyszenie się wykonawców.
EN
The paper discusses acoustical aspects of musical activity in St Mary Magdalene church in Lviv. The concept of improving acoustical qualities of the church when employed as a concert hall is presented. Current acoustics of the church meets both liturgical and musical requirements as long as the convention of using it as a historical object is maintained.
Ekrany akustyczne mogą odbijać, pochłaniać lub rozpraszać dźwięki. Ekran ze specjalnie zaprojektowaną powierzchnią dyfuzyjną ma wysoki stopień rozpraszania dźwięku. Ma również możliwość pochłaniania dźwięku dzięki komorom i systemem perforacji. Te właściwości umożliwiają zastosowanie ekranu do ochrony przed hałasem drogowym.
EN
Acoustic screen can reflect, absorb or scatter a sound. Screen with especially designed diffusion surface gives high degree of sound scattering. It has also possibility of sound absorbing by mean of cells and perforation system. These characteristic features make possible the use of such screen for protection against road noise.
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