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1

Miniature omnidirectional sound sources used in acoustic scale modeling - measurements and validation

Chojnacki Bartłomiej

Vibrations in Physical Systems

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2022

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Vol. 33, nr 2

art. no. 2022201

EN

Acoustic measurements such as scale modeling measurements require a particular type of miniature omnidirectional sound source. The most important aspects of those devices are small sizes (usually below 100 mm in diameter) and different frequency ranges compared to traditional, omnidirectional sound sources used in room acoustics. The required frequency range differs regarding the used scale factor in different models, which leads to the troubles in frequent source changes and the need for a unique source design for every model. The project will present the recent achievement in miniature omnidirectional sound sources development. The optimal sound sources for the given measurement functions were developed based on the previous numerical simulations and experiments such as FEM sound directivity simulations or transducers' parameters tolerance testing. The sound sources presented are used for applications such as acoustic sound insulation scale measurements (frequency range 800 ÷ 63 000 Hz), scaled reverberation chamber measurements (300 ÷ 80 000 Hz), or acoustic reduction models measurements (400 ÷ 70 000 Hz). The paper will cover a detailed technical explanation of the laboratory environment's source construction aspects and validation measurements.

2

Application of an ambisonic microphone for the measurements of room acoustic parameters

Jasiński Maciej, Żera Jan

Vibrations in Physical Systems

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2022

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Vol. 33, nr 3

art. no. 2022312

EN

The most commonly used measurement technique in room acoustics employs a single omnidirectional microphone for recording the room impulse response and further derivation of such acoustical parameters as T30, EDT, C50 or C80. Instead, ambisonic technology makes it possible to measure a spatial room impulse response. Ambisonics decomposes the signal from the spherical microphone array into spherical harmonics to shape the directivity. Ambisonics lets to go beyond basic acoustical parameters and allows to determine spatial features of a sound field at the measurement point. This study presents the comparison of fundamental acoustic parameters measured in the recording studio by an actual omnidirectional microphone and virtual omnidirectional microphones derieved from ambisonic microphones of the first and third order. The results show the usefulness of ambisonic technology in terms of assessing basic room parameters.

3

Mineralna izolacja natryskowa jako materiał poprawiający akustykę wnętrz

Marchacz Michał, Nowoświat Artur

Materiały Budowlane

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2022

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nr 8

14--16

PL

W artykule przedstawiono parametry akustyczne pianki natryskowej. Wyniki badań współczynnika pochłaniania dźwięku w komorze pogłosowej wskazują, że ma ona dobre właściwości dźwiękochłonne. Wyniki zweryfikowano przez zastosowanie materiału w pomieszczeniu o przeznaczeniu sakralnym w kształcie kopuły i o kubaturze 14 850 m3. Po zastosowaniu materiału czas pogłosu uległ znacznemu obniżeniu, co poprawiło warunki pogłosowe w pomieszczeniu.

EN

The article presents the acoustic parameters of the foam spray. The results of sound absorption coefficient obtained in the reverberation chamber show that the material has good soundproofing properties. Results were verified by applying the material in a dome-shaped sacral room with a cubature of 14 850 m3. Thanks to the use of the material, the reverberation time was significantly reduced. It has improved the reverberation conditions in the room.

4

Wibroizolacja to kosztowna fanaberia czy praktyczne rozwiązanie inżynierskie?

Tekielak Mateusz

Chłodnictwo i Klimatyzacja

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2022

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nr 1

38--39

PL

Większość krajów europejskich wdraża lokalnie przepisy prawne dotyczące wymagań akustycznych we wszystkich rodzajach budynków: publicznych, jednorodzinnych, przemysłowych. Nowo budowane obiekty muszą być zgodne z określonymi normami i przepisami budowlanymi, natomiast żadne przepisy nie zawierają wytycznych dotyczących renowacji starych budynków w zakresie akustyki. Tymczasem kwestie komfortu akustycznego stały się ważne dla wszystkich użytkowników, bez względu na datę powstania obiektu. Warto to brać pod uwagę i zadbać o komfort akustyczny na możliwie najwcześniejszym etapie prac w budynku - będzie prościej i taniej.

5

Ocena jakości akustycznej pomieszczeń biurowych typu open space z uwzględnieniem normy ISO 22955:2021

Mikulski Witold

Bezpieczeństwo Pracy : nauka i praktyka

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2022

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nr 12

22-27

PL

W PN-B-2151-4:2015 wyróżnia się dwa typy wielkopowierzchniowych pomieszczeń pracy: grupę 1 - pomieszczenia biurowe open space (inaczej zwane otwartymi pomieszczeniami do prac administracyjnych), sale operacyjne banków i urzędów, biura obsługi klienta, oraz grupę 2 - centra obsługi telefonicznej. W każdej z tych grup określona jest minimalna chłonność akustyczna pomieszczenia. W PN-EN ISO 3382-3:2012 wprowadzono cztery inne kryteria akustyczne pomieszczeń, dotyczące grupy 2. Do stanowisk pracy lub wymienionych pomieszczeń odnoszą się także kryteria związane z dopuszczalnym hałasem, określone w PN-N-01307:1994 oraz PN-B-02151-2:2018. Omawiane kryteria opracowano od 28 do czterech lat wstecz i w wielu przypadkach nie są one w pełni dostosowane do obecnie eksploatowanych pomieszczeń. Skutkiem tego było wprowadzenie w nowej normie ISO 22955:2021 nowego podziału wielkopowierzchniowych pomieszczeń pracy na sześć klas, w tym klasy pomieszczeń przeznaczonych do pracy biurowej, ale bez wyposażenia. W artykule omówiono wymagania oraz podano kryteria oceny pomieszczeń biurowych open space według ISO 22955:2021 oraz norm: PN-N-01307, PN-B-02151-2, PN-B-02151-4 i PN-EN ISO 3382-3.

EN

The Polish standard PN-B-02151-4: 2015 distinguishes two types of large-area work rooms: 1 - open plan offices, operating rooms for banks and offices, customer service offices and 2 - call centres. In each of these types, criteria for the minimum sound absorption of the room are defined. The PN-EN ISO 3382-32012 specifies four other acoustic criteria for rooms, but referring only to rooms type 2. For workplaces or the above-mentioned the rooms are also subject to the criteria for permissible noise specified in the PN-N-01307:1994 and the PN-B-02151-2:2018 standards. Above the criteria were developed from 28 to 4 years ago and in many cases are not fully adapted to the currently used rooms. As a result, the new ISO 22955: 2021 introduced a new division of open plan offices spaces/rooms. There are five types of used rooms and an additional class i.e. a room intended for office work, but without equipment. The article will discuss the acoustic requirements and the evaluation criteria of the rooms according to ISO 22955:2021 and the standards: PN-N-01307, PN-B-02151-2, PN-B-02151-4 and PN-EN ISO 3382-3.

6

Impact of Wall Impedance Phase Angle on Indoor Sound Field and Reverberation Parameters Derived from Room Impulse Response

Meissner Mirosław, Zieliński Tomasz

Archives of Acoustics

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2022

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Vol. 47, No. 3

343--353

EN

Accurate definition of boundary conditions is of crucial importance for room acoustic predictions because the wall impedance phase angle can affect the sound field in rooms and acoustic parameters applied to assess a room reverberation. In this paper, the issue was investigated theoretically using the convolution integral and a modal representation of the room impulse response for complex-valued boundary conditions. Theoretical considerations have been accompanied with numerical simulations carried out for a rectangular room. The case of zero phase angle, which is often assumed in room acoustic simulations, was taken as a reference, and differences in the sound pressure level and decay times were determined in relation to this case. Calculation results have shown that a slight deviation of the phase angle with respect to the phase equal to zero can cause a perceptual difference in the sound pressure level. This effect was found to be due to a change in modal frequencies as a result of an increase or decrease in the phase angle. Simulations have demonstrated that surface distributions of decay times are highly irregular, while a much greater range of the early decay time compared to the reverberation time range indicates that a decay curve is nonlinear. It was also found that a difference between the decay times predicted for the complex impedance and real impedance is especially clearly audible for the largest impedance phase angles because it corresponds approximately to 4 just noticeable differences for the reverberation metrics.

7

Acoustic Characterization of a Room : Study Case Between Simulation and a Portable Method

Ibarra-Zarate David, Padilla-Ortiz Ana Laura

Archives of Acoustics

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2020

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Vol. 45, No. 1

153--163

EN

Large venues and auditoriums are commonly associated with their astounding architecture. Their acoustic quality is an essential factor in its qualification as a great and functional, or a badly designed place. However, acoustics is often overlooked during the design stage of a building due to the complexity and high cost of the measurements involved. For this reason, it is important to explore more accessible ways to implement acoustics evaluations. The aim of this work is to compare typical experimental measuring methods and the use of mobile devices to assess the acoustic quality of a room. These measurements are contrasted with the software simulation of the same acoustical space. The results show that the mobile system can be used for professional measurements with low restrictions in the frequency range of interest of this study (90 Hz to 4000 Hz).

8

Prediction of low-frequency sound field in rooms with complex-valued boundary conditions on walls

Meissner Mirosław

Vibrations in Physical Systems

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2019

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Vol. 30, nr 1

art. no. 2019127

EN

A modal representation of a room impulse response has been used to formulate expressions for low-frequency sound field in rooms of arbitrary shape. Based on theoretical results, a simulation program has been developed to predict a sound pressure distribution and a room transfer function for rectangular enclosure having walls covered by a material of complex impedance. Calculation results have shown that changes in the wall reactance entail a substantial modification of a sound pressure distribution. Furthermore, an influence of wall reactance on the room transfer function was investigated and it was discovered that a change in a reactance sign causes a shift in frequencies of modal vibrations excited in the room.

9

Effectiveness of acoustic banners depending on their arrangement in the concert hall - case study

Kozłowski Piotr Z.

Vibrations in Physical Systems

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2019

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Vol. 30, nr 1

art. no. 2019141

EN

One of the most frequently used methods of adjusting the room acoustics of concert halls is the temporary introduction of additional acoustic absorption in the form of acoustic banners. Banners are implemented in the form of fabric surfaces placed vertically or horizontally along the walls of concert halls. In practice, one or two layers of heavyweight fabrics are used, characterized by a high value of the sound absorption coefficient. Simplified methods of designing acoustic banners assume estimating the effectiveness of adjusting the reverberation time on the basis of the static theory. The paper presents the results of measuring the effectiveness of acoustic banners carried out in the concert hall. The possibility of tuning the interior acoustics was verified depending on the position of the banner in the room as well as the degree of its opening.

10

Projektowanie adaptacji akustycznej otwartych pomieszczeń do prac administracyjnych. Część 1. Projektowanie podstawowe

Mikulski Witold

Materiały Budowlane

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2019

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nr 8

16--20

PL

Projektowanie akustyczne pomieszczeń biurowych open space polega na takim uwzględnieniu w pomieszczeniu różnych wyrobów dźwiękochłonnych, aby uzyskać wymagane przepisami warunki akustyczne. W artykule projektowanie podzielono na dwa etapy. Etap pierwszy, wymagany przez przepisy polskie, to uzyskanie w pomieszczeniu wymaganej chłonności akustycznej. Natomiast etap drugi polega na takiej aranżacji akustycznej pomieszczenia i stanowisk pracy, aby uzyskać w nim wymagane warunki propagacji (a właściwie separacji) dźwięków mowy między stanowiskami pracy. Zewzględu na objętość, artykuł podzielono na dwie części. W części pierwszej opisano pierwszy etap projektowania (podano metodę obliczeniową wg PN-B-02151-4:2015 i przykład). W części drugiej, w następnym artykule, opisany zostanie etap drugi projektowania wraz z podaniem przykładu (z wykorzystaniem programu ODEON).

EN

The acoustic design of the open plan office consists in taking into account various sound-absorbing products in the room to achieve the required acoustic conditions. In the article design is divided into two stages. The first stage, obligatory by Polish regulations, is to obtain the room's required sound absorption. The second stage consists in such an acoustic arrangement of the room and workstations to obtain the required conditions for the propagation (or actually separation) of speech sounds between workstations. Due to the volume, the article has been divided into two parts. The first part (this one) describes the first design stage (the calculation method according to PN-B-02151-4:2015 standard and example are given). In the second part, in the next article, the second design stage (using the ODEON software) will be described.

11

Projektowanie adaptacji akustycznej otwartych pomieszczeń do prac administracyjnych. Część 2. Projektowanie dodatkowe

Mikulski Witold

Materiały Budowlane

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2019

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nr 9

82--85

PL

Projektowanie akustyczne otwartych pomieszczeń do prac administracyjnych (tzw. biurowych open space) można podzielić na dwa etapy. Etap pierwszy, obligatoryjny (podstawowy) wymagany przez przepisy, zakłada uzyskanie w pomieszczeniu wymaganych warunków pogłosowych (odpowiednio dużej chłonności akustycznej; omówiony został w artykule autora w „Materiałach Budowlanych” nr 8/2019). Etap drugi (dodatkowy) polega na takiej aranżacji pomieszczeń i stanowisk pracy oraz uwzględnieniu w pomieszczeniu różnych dodatkowych wyrobów dźwiękochłonnych, np. ekranów akustycznych, aby uzyskać w nim wymagane warunki propagacji (a właściwie separacji) dźwięków mowy między stanowiskami pracy. W ramach projektowania dodatkowego podano wyniki obliczeń metodą wg PN-EN ISO 3382-3:2012 siedmiu wariantów adaptacji akustycznej pomieszczenia.

EN

Acoustic design of open plan office can be divided into two stages. The first stage, obligatory by Polish regulations, is to obtain the room's required sound absorption. It was discussed in the author's article in "Building Materials" No. 8/2019. The second (additional) stage consists in such arrangement of rooms and work stations and taking into account various additional sound-absorbing products, e.g. acoustic screens, in order to obtain the required conditions for the propagation (or actually separation) of speech sounds between workplaces. As part of the additional design, results of calculations according to the EN ISO 3382-3:2012 method of seven variants of the room's acoustic treatment are given.

12

Adaptation of coutyards into covered and glazed atriums and its impact on the level of acoustic comfort inside – case study

Ziarko B.

Technical Transactions

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2018

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Vol. 115, iss. 9

133--140

EN

Increasingly popular, in the area of modernization or revitalization of historic buildings, is the creation of a roof that is often fully glazed over the inner courtyard, thus creating a new spacious interior capable of performing many functions. The acoustics evaluation undertaken in this article was carried out on the basis of measurements and simulation of reverberation time in The Home Army Museum building in Cracow.

PL

Coraz popularniejsze staje się w ramach rewitalizacji zabytkowych obiektów wykonanie zadaszenia nad dziedzińcem wewnętrznym i stworzenia tym samym nowego przestronnego wnętrza mogącego pełnić bogate funkcje. Podjęta w artykule ocena akustyki wnętrza została wykonana na podstawie pomiarów i symulacji czasu pogłosu w budynku Muzeum Armii Krajowej w Krakowie.

13

Wpływ kubatury sal do indywidualnych prób muzycznych na akustykę w ich wnętrzu

Warzocha K.

Materiały Budowlane

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2018

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nr 8

20--22

PL

W artykule omówiono najczęściej popełniane błędy przy projektowaniu sal do prób muzycznych. Szczególną uwagę zwrócono na zbyt małą kubaturę pomieszczeń, w których instrumenty muzyczne generują dźwięki o parametrach przewyższających dopuszczalne wartości. Na podstawie przeprowadzonych analiz przedstawiono wpływ kubatury sal do indywidualnych prób muzycznych na poziom ciśnienia akustycznego w ich wnętrzu. Zaproponowano podział sal, ze względu na rodzaj instrumentu muzycznego, jako jeden ze sposobów poprawy procesu projektowania tego typu pomieszczeń.

EN

The article discusses the most common mistakes made during the design of rehearsal music rooms. Particular attention has been paid to the insufficient rooms' volume, where musical instruments generate sounds with parameters exceeding the permissible values. Based on the analyzes carried out, the influence of volume of individual rehearsal music rooms on the sound pressure level in their interior was presented. A division of rooms was proposed, due to the type of musical instrument, as one of the ways to improve the design process of this type of rooms.

14

Speech Intelligibility Test for Polish Language – Relation to the Acoustic Properties of Classrooms and Comparison to Other Languages

Radosz J.

Archives of Acoustics

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2018

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Vol. 43, No. 1

129--135

EN

Numerous studies have shown that teachers often speak louder in classrooms because of the acoustic properties of the spaces. To improve the acoustics in classrooms, it is necessary to develop relevant acoustic criteria. Existing evaluation scales for parameters of room acoustics have been developed on the basis of studies of adults for a variety of languages (e.g. Dutch and English). One of the issues still not fully recognized is the effect of the respondents’ language and age on the results of speech intelligibility tests. The aim of the study was to recognize the possibility of applying some international guidelines for room acoustics developed on the basis of adult studies to classrooms in Polish schools. This paper presents a study of the speech intelligibility of Polish-speaking children (10–13 years old) in conjunction with parameters of room acoustics. It also compares studies of speech intelligibility for other languages. The study confirmed a relationship between the results of speech intelligibility tests and speech transmission index STI for classrooms with varied acoustics. It also showed that the results of Polish word test are similar to results of English tests (Anderson, Kalb, 1987; Jacob et al., 1990).

15

Sound Behaviour of Concrete Churches. The Church of Santa Cruz de Oleiros

Bueno A. M., Galindo M., León A. L.

Archives of Acoustics

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2018

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Vol. 43, No. 2

297--306

EN

The church of Santa Cruz de Oleiros, Spain (1967) shows architect Miguel Fisac’s perception of sacred space after the Second Vatican Council. In this place of worship, the architect responded to the new liturgical guidelines combining geometry and architectural forms with the material of the moment, concrete. However, ordinary religious celebrations reveal acoustic deficiencies for the main use of the building. This fact is corroborated by acoustic measurements in situ. With a methodology that uses simulation techniques for the sound field, the analysis of the current acoustic behaviour of the room will serve as the basis for an acoustic rehabilitation proposal aimed at improving the acoustic conditions and so, the functionality of the church.

16

Formation of Scattering Characteristics for Acoustical Ray Tracing Simulation

Bojičić S., Šumarac-Pavlović D., Mijić M.

Archives of Acoustics

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2018

|

Vol. 43, No. 4

657--667

EN

Ray tracing simulation of sound field in rooms is a common tool in room acoustic design for predicting impulse response. There are numerous commercial engineering tools utilising ray tracing simulation. A specific problem in the simulation is the modelling of diffuse reflections when contribution of individual surface is prevailing. The paper introduces modelling of scattering which is interesting when the whole impulse response of a room is not a goal but contribution of certain surface. The main goal of the Project is to shape directivity characteristics of scattered reflection. Also, an innovative approach is suggested for converting the energy histogram information obtained by ray tracing into an “equivalent impulse response”. The proposed algorithm is tested by comparing the results with measurements in a real sound field, realised in a scaled model where a diffusing surface is hardware-implemented.

17

A Rough Estimation of Acoustics of the Cuboidal Room with Impedance Walls

Kocan-Krawczyk A., Brański A.

Archives of Acoustics

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2018

|

Vol. 43, No. 2

227--233

EN

The cuboidal room acoustics field is modelled with the Fourier method. A combination of uniform, impedance boundary conditions imposed on walls is assumed, and they are expressed by absorption coefficient values. The absorption coefficient, in the full range of its values in the discrete form, is considered. With above assumptions, the formula for a rough estimation of the cuboidal room acoustics is derived. This approximate formula expresses the mean sound pressure level as a function of the absorption coefficient, frequency, and volume of the room separately. It is derived based on the least-squares approximation theory and it is a novelty in the cuboidal room acoustics. Theoretical considerations are illustrated via numerical calculations performed for the 3D acoustic problem. Quantitative results received with the help of the approximate formula may be a point of reference to the numerical calculations.

18

A Novel Method for Determining Optimum Dimension Ratios for Small Rectangular Rooms

Meissner M.

Archives of Acoustics

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2018

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Vol. 43, No. 2

217--225

EN

A new method for determining optimum dimension ratios for small rectangular rooms has been presented. In a theoretical model, an exact description of the room impulse response was used. Based on the impulse response, a frequency response of a room was calculated to find changes in the sound pressure level over the frequency range 20-200 Hz. These changes depend on the source and receiver positions, thus, a new metric equivalent to an average frequency response was introduced to quantify the overall sound pressure variation within the room for a selected source position. A numerical procedure was employed to seek a minimum value of the deviation of the sound pressure level response from a smooth fitted response determined by the quadratic polynomial regression. The most smooth frequency responses were obtained when the source was located at one of the eight corners of a room. Thus, to find the best possible dimension ratios, in the numerical procedure the optimal source position was assumed. Calculation results have shown that optimum dimension ratios depend on the room volume and the sound damping inside a room, and for small and medium volumes these ratios are roughly 1 : 1.48 : 2.12, 1 : 1.4 : 1.89 and 1 : 1.2 : 1.45. When the room volume was suitably large, the ratio 1 : 1.2 : 1.44 was found to be the best one.

19

Akustyka a multimedia

Żera J.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2017

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nr 6

177--184

PL

Przedstawiono wybrane aspekty badań akustycznych nad dźwiękiem i jego percepcją znajdujące zastosowanie we współczesnych multimediach. Skoncentrowano się na zagadnieniach związanych z przestrzennym słyszeniem dźwięku oraz niektórych zagadnieniach związanych z funkcjami HRTF umożliwiającymi uzyskanie przestrzennego dźwięku przy odsłuchu słuchawkowym. W ograniczonym zakresie przedstawiono techniki numeryczne symulowania propagacji dźwięku w pomieszczeniach, odtwarzania wirtualnego dźwięku przestrzennego w systemach głośnikowych oraz matryc mikrofonowych.

EN

The review presents selected studies in acoustics and sound perception relevant to multimedia technology. Topics discussed include basic issues of spatial hearing and basics of the HRTF functions designed to obtain three dimensional spatial sound with the use of earphones. Further discussion continues on basic issues related to numerical simulations of room acoustics, creating virtual spatial sound with the loudspeaker systems and use of the microphone arrays.

20

Projektowanie adaptacji akustycznej pomieszczenia biurowego open space z wykorzystaniem programu ODEON

Mikulski W.

Przegląd Mechaniczny

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2017

|

nr 4

37--41

PL

W artykule przedstawiono wyniki obliczeń przy użyciu programu ODEON różnych wariantów adaptacji akustycznej pomieszczenia biurowego open space. Znaleziono taki wariant, który w połączeniu z sygnałami maskującymi mowę pozwolił uzyskać spełnienie wymagań akustycznych pomieszczeń określonych wieloma kryteriami podanymi w PN-B-02151-4:2015 i PN-EN ISO 3382-3:2012. W procesie projektowania adaptacji akustycznej pomieszczeń konieczne jest zapewnienie optymalizacji rozwiązań, gdyż różne elementy adaptacji akustycznej w wielu przypadkach powodują spełnienie jednych kryteriów, a jednocześnie niespełnienie innych. Stosunkowo najłatwiej jest uzyskać odpowiednie warunku pogłosowe pomieszczenia oraz odpowiedni poziom dźwięku A w odległości 4 m od mówiącego. Dużo trudniej jest spełnić warunki akustyczne określone spadkiem poziomu dźwięku na podwojenie odległości od mówiącego (stosując dużą liczbę wysokich ekranów akustycznych). Najtrudniej uzyskać odpowiednio małą zrozumiałość mowy (tj. prywatność) określone promieniem rozproszenia (stosując wysokie ekrany akustyczne oraz źródła maskujące mowę).

EN

The article presents the results of calculations by ODEON software for different variants of acoustic treatment in an open plan office. A variant has been found, that al-lows fulfilling the acoustic requirements specified by multiple criteria in PN-B-02151-4; 2015 and BS EN ISO 3382-3:2012 when combined with the sounds of speech masking. During the process of designing an acoustic treatment of rooms it is necessary to provide optimized solutions, since different elements of the acoustic treatment, in many cases result in fulfilling criteria and at the same time not fulfilling the other criteria. It is relatively easy to get the proper reverberant conditions in a room and ad-equate sound pressure level from the speaker at a distance of 4 m (using sound absorbing ceilings and materials on the walls and sound absorbing materials on the sur-face of acoustic screens). It is much harder to meet the acoustic conditions specified by decrease of the sound pressure level with the distance from the speaker The most difficult is to obtain sufficiently low speech intelligibility (ie. privacy) specified by scattering radius (using high acoustic screens and of speech masking sources).