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1

The effect of evanescent modes on low-frequency sound field in rectangular rooms

Meissner Mirosław

Vibrations in Physical Systems

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2023

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Vol. 34, nr 2

art. no. 2023205

EN

The paper investigates the sound field excited by a boundary pure-tone source in rigid-walled rectangular rooms. This approach is applicable in the low-frequency range, where sound absorption by wall surfaces can be considered negligible. The sound pressure was theoretically determined by applying the Green's function based on the cut-on and evanescent modes expansion instead of the usual normal mode expansion. The theoretical model was used to predict the spatial distribution of the sound pressure level at different source frequencies. The calculation results have shown that for audible frequencies below the cut-off frequency, the plane wave mode and evanescent modes strongly interfere which results in an interference pattern with large dips in the pressure level forming a continuous curve. A shape of this curve is highly dependent on the excitation frequency. These dips have been found to occur when the sound associated with the plane wave mode is cancelled by the sound produced by evanescent modes.

2

Elimination of the Phase Mismatch Error in PP Probe Using Synchronous Measurement Technique

Raczyński Michał

Pomiary Automatyka Robotyka

|

2022

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R. 26, nr 2

35--46

EN

The paper presents a modification of the pressure-pressure (PP) sound intensity measurement method. In the proposed solution simultaneous measurement with a pair of microphones (used in the classical PP probe) is replaced by a sequence of measurements taken with a single microphone placed in successive positions. This approach requires an additional (reference) microphone to synchronize the successive measurements. Although, in the process of calculating the sound intensity only the signal from the measurement microphone is used. Thanks of this the errors associated with differences in the frequency responses of the measurement microphones (especially phase mismatch error) that occurs in the classical PP method are eliminated. This approach simultaneously increases the random error and limits the measurements to periodic signals only. The article presents the principle of operation of the classical PP probe and the currently used methods of phase mismatch error elimination based on pre-calibration of the probe. Next, the theoretical basis of the proposed measurement method is described. To verify the effectiveness of phase mismatch error elimination in the proposed method, an experiment was conducted. It consisted in estimation the angle of incidence of an acoustic wave under controlled conditions in an anechoic chamber. The measurement was carried out with the classical PP probe and with the modified method. Measurements were made for different sound sources (a loudspeaker set and a small electrical device). In the final part of the paper, the results are discussed, both methods (classical and modified) are compared and potential applications of the proposed method are indicated.

PL

W artykule zaprezentowano modyfikację metody pomiaru natężenia dźwięku z wykorzystaniem sondy PP (ang. pressure-pressure). W zaproponowanym rozwiązaniu jednoczesny pomiar ciśnienia akustycznego za pomocą dwóch mikrofonów pomiarowych (używanych w klasycznej sondzie PP) został zastąpiony sekwencją pomiarów dokonywanych jednym mikrofonem pomiarowym umieszczanym w kolejnych pozycjach. Zaproponowana metoda pozwala na eliminację błędu związanego z niejednakowymi odpowiedziami częstotliwościowymi (głównie fazowymi) mikrofonów użytych w klasycznej sondzie PP. Jej zastosowanie jest ograniczone do pomiaru sygnałów okresowych. Jednocześnie wzrasta błąd przypadkowy, który można jednak wyeliminować metodami statystycznymi. Pomimo, że zaproponowane podejście wymaga zastosowania mechanizmu synchronizacji pomiarów i użycia w tym celu dodatkowego mikrofonu pomocniczego, to w samym procesie wyznaczania natężenia dźwięku bierze udział jedynie sygnał z mikrofonu pomiarowego. W artykule zaprezentowano zasady pomiaru natężenia dźwięku za pomocą klasycznej sondy PP oraz obecnie stosowane metody eliminacji błędów związanych z niedopasowaniem charakterystyk częstotliwościowych mikrofonów, bazujące na wstępnej kalibracji sondy. Następnie przedstawione są teoretyczne podstawy zaproponowanej metody pomiarowej. Aby zweryfikować jej skuteczność przeprowadzono eksperyment pomiarowy polegający na pomiarze kąta padania fali akustycznej w ściśle określonych warunkach w komorze bezechowej. Eksperyment przeprowadzono z wykorzystaniem klasycznej metody PP oraz z wykorzystaniem zaproponowanej metody zmodyfikowanej. Dokonano pomiarów dla różnych źródeł dźwięku (zestawu głośnikowego oraz małego urządzenia elektrycznego). W końcowej części artykułu wyniki porównawcze są poddane dyskusji w celu wskazania potencjalnych zastosowań zaproponowanej metody.

3

Measurements of acoustic response of car interion for structural excitations

Paluch Wojciech, Kłaczyński Maciej

Diagnostyka

|

2022

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Vol. 23, No. 4

art. no. 2022413

EN

The transition from internal combustion to electric propulsion in cars presents component designers with new challenges in terms of noise reduction. Until now, components such as the suspension, its knocks were masked by the combustion engine or exhaust system. The absence of such significant sources, means that hitherto inaudible components are starting to become a nuisance. In order to reduce their noise, a number of optimisation solutions, both active and passive, are used. In order to do so, relevant measurements and data analysis must be carried out. This paper aims to present the acoustic characteristics of the interiors of two cars excited structurally in the vicinity of the front shock absorber mounting and by the operation of another component, the windscreen wipers on dry and wet windscreens. Measurements were made using 3D intensity probes based on acoustic particle velocity sensors. The results, in the form of both acoustic particle velocity and sound pressure characteristics and spectrograms, are presented comparatively for two types of car.

4

Analysis of acoustic propagation of automotive cooler during run up and run down

Paluch Wojciech, Kłaczyński Maciej

Diagnostyka

|

2021

|

Vol. 22, No. 4

3--8

EN

The modern automotive industry invests more and more in electric drive technology. As a result, new challenges arise in terms of vibroacoustic optimization of the car interior. Components that were once masked by the internal combustion engine are starting to dominate the interior of vehicles. There is therefore a great need for noise reduction. For this purpose, a number of methods of its reduction are used, i.e. component optimization (source), use of active noise reduction systems or passive soundproofing materials. In order to perform the abovementioned noise reduction measures, appropriate measurements and signal analysis should be carried out. This presentation aims to present the measurement of an automotive air cooler in transient states on the stand. Measurements were made using a 3D intensity probe based on the direct measurement of the acoustic particle velocity, in 3 planes in front of the cooler. Then, order tracking analysis was performed for the run-up and coast-down. The results in the form of selected orders of intensity and acoustic particle velocity were compared with classical results made with the use of a microphone at the same measurement points locations.

PL

Współczesny przemysł motoryzacyjny inwestuje coraz bardziej w technologię napędu elektrycznego. W związku z tym pojawiają się nowe wyzwania w zakresie optymalizacji wibroakustycznej wnętrza samochodu. Komponenty, które kiedyś były maskowane przez silnik spalinowy zaczynają dominować we wnętrzu pojazdów. Istnieje zatem duża potrzeba redukcji hałasu. W tym celu stosuje się szereg metod jego redukcji, tj. optymalizacja komponentu (źródła) zastosowanie aktywnych systemów redukcji hałasu lub pasywnych materiałów wygłuszających. Aby dokonać wspomnianych zabiegów redukujących hałas, należy przeprowadzić stosowne pomiary oraz analizę sygnałów. Niniejsza prezentacja ma na celu przedstawienie pomiaru chłodnicy samochodowej w stanach nieustalonych na stanowisku. Pomiarów dokonano przy użyciu sondy natężeniowej 3D bazującej na bezpośrednim pomiarze prędkości akustycznej cząsteczek, w 3 płaszczyznach przed chłodnicą. Następnie wykonano analizę rzędów (order tracking) dla rozbiegu oraz wybiegu. Wyniki w formie wybranych rzędów (orderów) natężeń oraz prędkości akustycznej cząstek zestawiono z klasycznymi wynikami wykonanymi przy użyciu mikrofonu w tych samych punktach pomiarowych.

5

Modified pressure-pressure sound intensity measurement method and its application to loudspeaker set directivity assessment

Mickiewicz Witold, Raczyński Michał

Metrology and Measurement Systems

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2020

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Vol. 27, nr 1

181--194

EN

Sound intensity measurements using special sensors in a form of pressure-velocity and pressure-pressure probes are becoming more and more often the method of choice for characterization of sound sources. Its wider usability is blocked by the probes’ costs. This paper is on a possible modification of the well-known pressure-pressure sound intensity measurement method. In the proposed new approach a synchronized measurement procedure using only single microphone is used. The paper presents the basics of the sound intensity theory, a review of currently used methods of intensity measurement and requirements and limitations of the new method. In the proposed approach one microphone and a properly designed positioning system is used. The application of the method to study the directional characteristics of an active loudspeaker system have been described in detail. The obtained results were compared with those of measurements performed with a commercial p-u probe. The paper contains conclusions indicating advantages of the applied method in comparison with standard pressure measurement methods.

6

Localization of noise sources in electric cookers based on sound pressure and intensity measurements

Jakubek Bartosz, Barczewski Roman, Tabaszewski Maciej

Vibrations in Physical Systems

|

2019

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Vol. 30, nr 2

art. no. 2019223

EN

The main aim of the study was to compare the features of acoustic maps created on the basis of measurements of sound pressure and intensity in a near acoustic field. Data for comparisons were obtained within the framework of acoustic tests of electric cookers. The results of these studies may help in the selection of acoustic mapping and optimization methods according to individual needs and/or requirements concerning selectivity, measurement bandwidth, dynamics and the ability to locate sound-emitting areas. The paper also presents the results of the spectral analysis of the dominant sources of noise in the cooker, which was helpful in identifying and locating paths of noise propagation from the inside of the cooker.

7

Effective diagnostic of local noise sources with acoustic imaging

Weyna Stefan

Vibrations in Physical Systems

|

2019

|

Vol. 30, nr 2

art. no. 2019201

EN

In this article, the author described methods of visualizing the acoustic flow and showed how these methods can help scientists understand the complex flow of acoustic energy in a real field. A graphical method for determining the distribution of acoustic waves in a real 3D flow field will be presented. Vector imaging of acoustic events is not possible with the use of traditional metrology applied in pressure acoustics. Based on research using measurements of sound intensity and distribution of vector acoustic field by acoustic orthogonal decomposition method (SI-AOD), the article will present examples of practical applications of these analyses. The described measurement technique, including the method of graphical presentation of results, enriches the knowledge about the mechanism of the flow of acoustic energy stream in real working conditions of the source. The SI-AOD analysis system sets a milestone in the monitoring of sound landscapes and the precise finds noise sources.

8

Mobilne stanowisko do wizualizacji pola akustycznego wokół maszyn

Szczepański Grzegorz, Morzyński Leszek, Pleban Dariusz

Bezpieczeństwo Pracy : nauka i praktyka

|

2019

|

nr 5

16-20

PL

Wizualizacja parametrów pola akustycznego to stosunkowo nowa metoda badawcza, która umożliwia zobrazowanie parametrów charakteryzujących pole akustyczne w konkretnych punktach przestrzeni w pobliżu maszyny. Obrazy uzyskane w ten sposób mogą mieć duże zastosowanie w analizie prototypowych urządzeń, budownictwie, a także w analizie pola akustycznego wokół maszyn przemysłowych. W artykule opisano sposób działania przykładowego, mobilnego stanowiska, wizualizującego pole akustyczne wokół maszyn. Omówiono również wyniki przeprowadzonych badań emisji hałasu na przykładzie zestawu głośnikowego i pompy próżniowej.

EN

Visualization of the parameters of acoustic field is a relatively new research technique that allows for illustrate the parameters characterizing the acoustic field for specific points of space near the machine. Images obtained in this way have many applications in the analysis of prototype devices, construction, as well as in the analysis of the acoustic field around industrial machines. The article presents the principles of operation of the mobile experimental setup. The results of studies of noise emission on the example of loudspeaker set and vacuum pump are also discussed.

9

Alfabet PIUSWIKa (9) – H jak HAŁAS

Maciąg G.

Technika Chłodnicza i Klimatyzacyjna

|

2017

|

nr 10

395

PL

Kolejna odsłona stałej pozycji „Alfabet PIUSWIKa”, czyli Projektanta, Instalatora, Użytkownika Systemów Wentylacyjnych i Klimatyzacyjnych, poświęcona jest literze H, czyli hałasowi generowanemu przez urządzenia wentylacyjne. Hałas pochodzący od pracy wentylatora zależy od wielu czynników. Podstawowym elementem jest sama konstrukcja wentylatora, w której należy zwrócić uwagę na liczbę łopatek oraz ich kształt. Następnymi czynnikami są wydajność i ciśnienie, prędkość powietrza, a także wielkość i kształt obudowy (o ile w danej konstrukcji wentylatora obudowa w ogóle występuje) oraz jej sztywność. W opracowaniu przytoczone zostały zagadnienia, na które warto zwrócić uwagę podczas analizy rozwiązań układów wentylatorowych proponowanych przez dostawców urządzeń oraz podawane przez nich charakterystyki techniczne.

EN

This is the next part of series of papers dedicated to Designers, Installers and Users of Ventilating and Air Conditioning systems (PIUSWIK). It deals with the noise from air handling plants. There is a strong influence of the design of fan and its blades, air volume, pressure and speed as well as the design of fan’s housing. From this point of view it is worth to pay attention to the characteristic of ventilating systems published by manufacturers.

10

The Use of Acoustic Vectors Decomposition of Sound Fields to Vibroacoustic Protection on Ships

Weyna S.

Archives of Acoustics

|

2017

|

Vol. 42, No. 2

207--212

EN

In this paper, numerous examples will be illustrated as principles of applying the sound intensity measurements to practical problems at the noise abatement on ships and offshore constructions. The paper presents the results of transmission loss measurements together with flanking transmission for ship bulkheads and partitions with doors and windows. Investigations carried out with sound intensity measurement techniques will be compared against those made by classical methods. Finally for a few examples, the graphic presentation of spatial distribution of sound intensity vectors risen close to vibrating ship cabin partitions and inside the cabin will be shown in 2D and 3D graphical form. As a result, a two-dimensional acoustic wave flow map of time-averaged active intensity vectors propagated along curved streamlines and a vector perpendicular to measured plane are graphically illustrated. The technique of acoustic vectors decomposition of sound fields described, can enrich the knowledge of the mechanism of acoustic energy flux through ship partitions.

11

Sound Intensity Distribution Around Organ Pipe

Odya P., Kotus J., Szczodrak M., Kostek B.

Archives of Acoustics

|

2017

|

Vol. 42, No. 1

13--22

EN

The aim of the paper was to compare acoustic field around the open and stopped organ pipes. The wooden organ pipe was located in the anechoic chamber and activated with a constant air flow, produced by an external air-compressor. Thus, a long-term steady state response was possible to obtain. Multichannel acoustic vector sensor was used to measure the sound intensity distribution of radiated acoustic energy. Measurements have been carried out on a defined fixed grid of points. A specialized Cartesian robot allowed for a precise positioning of the acoustic probe. The resulted data were processed in order to obtain and visualize the sound intensity distribution around the pipe, taking into account the type of the organ pipe, frequency of the generated sound, the sound pressure level and the direction of acoustic energy propagation. For the open pipe, an additional sound source was identified at the top of the pipe. In this case, the streamlines in front of the pipe are propagated horizontally and in a greater distance than in a case of the stopped pipe, moreover they are directed downwards. For the stopped pipe, the streamlines of the acoustic flow were directed upwards. The results for both pipe types were compared and discussed in the paper.

12

A System for Acoustic Field Measurement Employing Cartesian Robot

Szczodrak M., Kurowski A., Kotus J., Czyżewski A., Kostek B.

Metrology and Measurement Systems

|

2016

|

Vol. 23, nr 3

333--343

EN

A system setup for measurements of acoustic field, together with the results of 3D visualisations of acoustic energy flow are presented in the paper. Spatial sampling of the field is performed by a Cartesian robot. Automatization of the measurement process is achieved with the use of a specialized control system. The method is based on measuring the sound pressure (scalar) and particle velocity(vector) quantities. The aim of the system is to collect data with a high precision and repeatability. The system is employed for measurements of acoustic energy flow in the proximity of an artificial head in an anechoic chamber. In the measurement setup an algorithm for generation of the probe movement path is included. The algorithm finds the optimum path of the robot movement, taking into account a given 3D object shape present in the measurement space. The results are presented for two cases, first without any obstacle and the other - with an artificial head in the sound field.

13

3D Acoustic Field Intensity Probe Design and Measurements

Kotus J., Czyżewski A., Kostek B.

Archives of Acoustics

|

2016

|

Vol. 41, No. 4

701--711

EN

The aim of this paper is two-fold. First, some basic notions on acoustic field intensity and its measurement are shortly recalled. Then, the equipment and the measurement procedure used in the sound intensity in the performed research study are described. The second goal is to present details of the design of the engineered 3D intensity probe, as well as the algorithms developed and applied for that purpose. Results of the intensity probe measurements along with the calibration procedure are then contained and discussed. Comparison between the engineered and the reference commercial probe confirms that the designed construction is applicable to the sound field intensity measurements with a sufficient effectiveness.

14

Overview of the experimental determination of acoustic flow on the basis of sound intensity measurements

Weyna S.

Mechanics and Control

|

2014

|

Vol. 33, no. 1

26--36

EN

A large variety of CFD/CAA hybrid approaches are commonly used today for aero-acoustic engineering applications using equations and the coupling between source and acoustic propagation region. The coupling is usually made using Lighthill 's acoustic analogies and Kirhchoff's acoustic boundary conditions. This paper intends to give answer how the size and shape of the source may be influence on the accuracy of the different coupling methods and their sensitivity. In this way, some experimental investigation was made using sound intensity measurement technique to the graphic presentation of the spatial distribution of the acoustic power flow over various geometrical shapes of structures located in a three-dimensional space. The results of these studies contribute to the theory of sound and general knowledge about the physics of flow acoustic phenomena, especially in the near acoustic field. As a result of research, the visualization analysis of the sound intensity flux in 3D space is shown as flow wave reactions on the presence of obstacles with different shapes. The results of vector flow fields around a rectangular and circular plate, over the cavity and inside a ducts are shown. The visualization of acoustic power flow in real-life acoustic fields can explain many particular energetic acoustic effects like scattering, vortex flow in shielding area, etc., concerning area where it is difficult to make numerical analysis.

XX

Duża różnorodność hybrydowych zastosowań technik CFD/CAA jest dzisiaj powszechnie używanym narzędziem w inżynierskich zastosowaniach aeroakustycznych wykorzystujących równania sprzęgające źródło drgań mechanicznych z polem propagacji akustycznej. Sprzęganie tych obszarów odbywa się zwykle za pomocą akustycznej analogii Lighthilla i akustycznych warunków brzegowych Kirhchoffa. W tej publikacji poszukuje się odpowiedzi, jak wielkość i kształt źródła wpływa na dokładność i wrażliwość różnych metod sprzęgania. W tym celu wykonano kilka badań eksperymentalnych z użyciem techniki pomiaru natężenia dźwięku obrazując przestrzenny rozkład przepływu energii akustycznej w otoczeniu przeszkód o różnych kształtach geometrycznych. Jako rezultaty badań przepływów pokazano reakcje fali akustycznej na różnego kształtu przeszkody wprowadzone w pole przepływowe. W formach graficznych przedstawiono wyniki badań przepływów wokół płaskiej i okrągłej płyty, nad wnęką akustyczną i we wnętrzach przewodów. Wizualizacja przepływu energii akustycznej w połach rzeczywistych może wyjaśnić wiele szczególnych efektów akustycznych, takich jak rozpraszanie i tworzenie się wirów za przeszkodą lub podobne reakcje w obszarach, dla których trudno jest budować modele numeryczne.

15

Multi-Modal Acoustic Flow Decomposition Examined in a Hard Walled Cylindrical Duct

Weyna S., Mickiewicz W.

Archives of Acoustics

|

2014

|

Vol. 39, No. 2

289--296

EN

Flow fields could be of great interest in the study of sound propagation in aeroengines. For ducts with rigid boundaries, the fluid-resonant category may contribute significantly to unwanted noise. An understanding of the multi-modal propagation of acoustic waves in ducts is of practical interest for use in the control of noise in, for example, aero-engines, automotive exhaust and heating or ventilation systems. The purpose of our experiments was to test the acoustic energy transmission of duct modes based on studies carried out by the sound intensity technique. Sound intensity patterns in circular duct are discussed of modal energy analysis with particular reference to proper orthogonal decomposition and dynamic mode decomposition. The authors try to justify some advantages of the sound intensity experimental research in this area. In the paper, the wide-band sound signal propagated from source approximated with loudspeaker in hard-walled duct is imaged using a sound intensity – based approach. For a simple duct geometry, the sound intensity field is examined visually and by performing a modal decomposition greater insight into the acoustic structures is obtained. The image of sound intensity fields below and above “cut-off” frequency region are found to compare acoustic modes which might resonate in duct.

16

Modele regresyjne sieci neuronowych do identyfikacji sygnału akustycznego zespołu napędowego drzwi dźwigu osobowego

Lonkwic P.

TTS Technika Transportu Szynowego

|

2013

|

R. 20, nr 10

2993--2999

PL

W opracowaniu przestawiono zastosowanie modeli regresyjnych sieci neuronowych dostępnych w pakiecie Statistica do identyfikacji sygnału akustycznego generowanego podczas pracy modułu napędowego drzwi dźwigu osobowego. Badania prowadzono w oparciu o pomiary wykonane na stanowisku laboratoryjnym za pomocą sonometru wyposażonym w dwa rodzaje silników elektrycznych zasilanych napięciem 380 V oraz 24 V z falownikiem. Przeanalizowano na ile metoda sieci neuronowych jest czuła na modyfikacje amplitudy natężenia dźwięku.

EN

The study presents the application of neuron network regressive models available in Statistica package for identifying the acoustic signal generated when the passenger lift door driving module works. the studies were conducted on the basis of measurements performed on laboratory stand with the use of objective noise meter ( sound level meter) equipped with two kinds of electric motors fed with the voltage of 380 V and 24 V with an inverter. It was analyzed, to what extent the neuron network method is sensitive to sound intensity amplitude modifications.

17

Assessment of energetistic measuring techniques and their application to diagnosis of acoustic condition of hydraulic machinery and equipment

Osiński P., Kollek W.

Archives of Civil and Mechanical Engineering

|

2013

|

Vol. 13, no. 3

313--321

EN

Energy methods in acoustic were introduced more than 40 years ago but new techniques of data analyses can give new possibility for hydraulic system health assessment. Possibilities of applying energetistic techniques to the measurement of complex vibroacoustic processes are presented using as an example a hydraulic feeder. These research methods open up new prospects for the reduction of noise emission in hydraulic machinery and equipment. The described vector techniques of locating sound sources by means of an acoustic probe and a measuring plane antenna deserve special attention. As a result of the measurement a distribution of the intensity of emissions originating from different parts of the source is obtained in the form of emission maps. The techniques can be applied to any object (e.g. a pump, a motor) to determine the main sources of noise emission and then this information can be used to improve the object's design. This paper is based on research in the fields of the design and operation of hydraulic systems, conducted for many years in the Institute of Machine Design and Operation at Wrocław University of Technology.

18

Experimental Acoustic Flow Analysis Inside a Section of an Acoustic Waveguide

Weyna S., Mickiewicz W., Pyła M., Jabłoński M.

Archives of Acoustics

|

2013

|

Vol. 38, No. 2

211--216

EN

Noise propagation within ducts is of practical concern in many areas of industrial processes where a fluid has to be transported in piping systems. The paper presents experimental data and visualization of flow in the vicinity of an abrupt change in cross-section of a circular duct and on obstacles inside where the acoustic wave generates nonlinear separated flow and vortex fields. For noise produced by flow wave of low Mach number, laminar and turbulent flows are studied us- ing experimental sound intensity (SI) and laser particle image velocimetry (PIV) technique adopted to acoustics (A-PIV). The emphasis is put on the development and application of these methods for better understanding of noise generation inside the acoustic ducts with different cross-sections. The intensity distribution inside duct is produced by the action of the sum of modal pressures on the sum of modal particle velocities. However, acoustic field is extremely complicated because pressures in non-propagating (cut-off) modes cooperate with particle velocities in propagating modes, and vice versa. The discrete frequency sound is strongly influenced by the transmission of higher order modes in the duct. By under- standing the mechanism of energy in the sound channels and pipes we can find the best solution to noise abatement technology. In the paper, numerous methods of visualization illustrate the vortex flow as an acoustic velocity or sound intensity stream which can be presented graphically. Diffraction and scattering phenomena occurring inside and around the open-end of the acoustic duct are shown.

19

Monitoring środowiska akustycznego w miejscowości Kolbuszowa w 2011 r.

Piechowicz B., Stawarczyk K., Stawarczyk M.

Zeszyty Naukowe Wyższej Szkoły Zarządzania Ochroną Pracy w Katowicach

|

2012

|

Nr 1(8)

45-51

PL

W okresie od lutego do września 2011 r. wykonywano pomiary poziomu dźwięku w sześciu reprezentatywnych dla danego typu zabudowy i użytkowania punktach miasta Kolbuszowa. Tak pora doby, jak i lokalizacja miejsca pomiarowego miały znaczący wpływ na środowisko akustyczne badanego obszaru. Analizy potwierdziły również, że w niektórych punktach miasta normy emisji dźwięków zostały znacznie przekroczone.

EN

From February to September 2011 measurements of sound levels in six representative areas in town of Kolbuszowa were made. It was found that in the studied region the time of day and measurement location had a strong impact on the acoustic environment. The research also confirmed that in some places in the town the sound emission standards were considerably exceeded.

20

Zautomatyzowany system do przestrzennego obrazowania pola akustycznego

Mickiewicz W., Jabłoński M. J.

Pomiary Automatyka Kontrola

|

2012

|

R. 58, nr 11

920-922

PL

W pracy przedstawiono zautomatyzowany system do przestrzennego obrazowania wektorowego pola akustycznego. Omówiono podstawy jego funkcjonowania wraz z implementacją Zawarto dyskusję dot. optymalizacji stosowanych algorytmów w celu ich przystosowywania do pracy na jednostkach obliczeniowych różnej mocy. Zaprezentowano wizualizacje dla dwóch modeli wykonane za pomocą nowego systemu oraz przeanalizowano osiągnięty zysk czasowy wynikający z jego użycia w porównaniu z systemem wcześniej stosowanym.

EN

In the paper an automatised system for spatial visualisation of the vector acoustic field is presented. There is discussed the theoretical basis of vector acoustic field visualization based on a vector parameter which is the sound intensity (formula (1)). The measuring method and practical implementation of the system which uses an intensity probe - Microflown USP are described. The presented system was created using the LabVIEW programming environment as two virtual instruments. The first virtual instrument integrates the acquisition and positioning blocks based on a DAQ card and a translating unit driver ISEL. The second instrument is responsible for converting the pressure and velocity components into the vector of sound intensity. This part is the most computationally complex operation performed by the system. The paper includes a discussion about optimisation of the used algorithms in order to adapt them to work on different class computing machines. There is proposed a serial and parallel solution of computing the sound intensity (Fig. 1). At the end of the paper a sample visualisation carried out by the new system for two models