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1

Vibration transmission analysis through mounting elements of wall cladding panels

Idczak Julia, Rubacha Jarosław, Kamisiński Tadeusz

Vibrations in Physical Systems

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2022

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Vol. 33, nr 2

art. no. 2022207

EN

Vibrations in building constructions may propagate through mounting elements to wall cladding panels. It is confirmed that they can have an impact on the sound pressure level radiated from panels and might have a significant influence on the total SPL in a room. In this work possibilities for calculating a parameter determining a change of SPL value depending on the number of panels and its mounting method are presented. A computational model based on vibration velocity measurements was used to estimate the total SPL value in a room. The laboratory and in situ measurements are presented. Transfer function for two elastic elements used as additional elements in a junction was calculated. Finally, ΔLp and ΔLv were calculated, as parameters defining the impact of various panel mounting methods on the reduction of sound pressure level and vibration level value, respectively.

2

Pomiary hałasu wytwarzanego przez źródła znajdujące się blisko ucha - na przykładzie zestawów słuchawkowych

Kozłowski Emil, Młyński Rafał

Bezpieczeństwo Pracy : nauka i praktyka

|

2022

|

nr 7

21-24

PL

W artykule przedstawiono wyniki pomiarów parametrów hałasu wytwarzanego przez zestawy słuchawkowe. Wyniki bezpośredniego pomiaru z zastosowaniem manekina akustycznego zostały skorygowane w taki sposób, aby otrzymane wartości odpowiadały warunkom pola swobodnego i można je było odnieść do obowiązujących w Polsce wartości kryterialnych oceny narażenia na hałas. W przypadku równoważnego poziomu dźwięku A wartości poprawki zostały wyznaczone według znormalizowanej metody, natomiast w przypadku maksymalnego poziomu dźwięku A i szczytowego poziomu dźwięku C zaproponowano własną metodę wyznaczania wartości tej poprawki. Zaprezentowane w artykule wyniki pomiarów potwierdziły, że w odniesieniu do badanych zestawów słuchawkowych, przy określonych ustawieniach układu wzmocnienia, nie wystąpiły przekroczenia wartości NDN oceny narażenia na hałas. Istnieje jednak możliwość przekroczenia progu działania w przypadku poziomu ekspozycji na hałas odniesionego do ośmiogodzinnego dobowego wymiaru czasu pracy. Ponadto pomiary wykazały, że wartości poprawki równoważnego poziomu dźwięku A, maksymalnego poziomu dźwięku A i szczytowego poziomu dźwięku C są do siebie zbliżone niezależnie od metody ich wyznaczania Wartości poprawki zależą zaś od zestawu słuchawkowego, który służy do odtwarzania sygnału testowego.

EN

The article presents the results of measurements of noise parameters generated by headsets. The results of direct measurement carried out using an acoustic manikin were corrected so that the obtained values corresponded to the free-field conditions and could be referred to the criterion values of noise exposure assessment in Poland. In case of A-weighted equivalent sound pressure level, the correction value was determined according to the normalized method. However, in case of A-weighted maximum sound pressure level and C-weighted peak sound pressure level the own method of determination of this correction was proposed. The results of measurements presented in the paper showed that for the tested headsets, at the specific settings of gain level, no exceedance of the noise exposure limit values occurred. However, it is possible that the action value may be exceeded for daily noise exposure level. Moreover, the measurements showed that the correction values for the A-weighted equivalent sound pressure level, A-weighted maximum sound pressure level and C-weighted peak sound pressure, regardless of the method of their determination, are similar to each other. However, the correction values depend on the headset, which was used to play the test signal.

3

Analytical and Computational Acoustic Modelling of Side Outlet Muffler and Its Extension in the Modelling of Tapered Side Outlet Muffler

Vishwakarma Sandeep Kumar, Pawar Jayappa

Archives of Acoustics

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2022

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Vol. 47, No. 4

491--499

EN

Mufflers are popular in the suppression of noise levels coming from various machinery. The most common parameters for the evaluation of the performance of mufflers are transmission loss, noise level, and insertion loss. The transmission loss is evaluated for tapered side outlet muffler using finite element analysis without considering the fluid-structure interaction. This study includes analytical modelling and acoustic modelling of the side outlet muffler and transmission loss is in excellent agreement with the reference paper. The feasibility of the acoustic model is also verified with the experimental work on simple expansion chamber muffler. The same finite element analysis is extended for the tapered side outlet muffler. The transmission loss of the tapered side outlet muffler in the given frequency range is found 8.96 dB better than the side outlet muffler. The acoustic pressure level and sound pressure level contours for the tapered side outlet muffler give a clear picture of wave propagation inside the muffler. The effect of the cut-off frequency on the transmission loss of the tapered side outlet muffler can be seen from the contours. This study can be helpful in the determination of the performance of the mufflers in terms of transmission loss, the performance of mufflers above cut-off frequency, and design improvements in the muffler to avoid the higher-order modes of the sound wave.

4

Noise emission from various shape rods at low-moderate Reynolds number

Kopania Joanna Maria, Bogusławski Grzegorz

Vibrations in Physical Systems

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2021

|

Vol. 32, nr 2

art. no. 2021202

EN

Aeroacoustic source localization is an important experimental tool and the first step to know the mechanism of noise generation. The flow around the various shape of rods is one of the major aeroacoustic noise source mechanism. Such rods represent simple models for technical applications like part of the landing gear of planes, train pantographs, antennas, vehicles part, ventilation system or bridge. The purpose of this paper is to clarify the influence of the rod shape in the noise generation mechanism in a low-moderate Reynolds number. In this work, the situation when various shape rods are in the area of laminar-turbulent flow was analyzed. The measurements were carried out for single circular, square, c-shape rods to study the noise effect depended on the Reynolds number. The measurements were performed on the specially constructed test stand with the outlet to the anechoic room. The 1/3 SPL differential spectrum as 2-D noise maps were obtained for studied rods. The acoustic differences between circular, square and U-beam rods were observed.

5

Estimation of sound power level of machine by inverse method

Piechowicz Janusz

Vibrations in Physical Systems

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2021

|

Vol. 32, nr 1

art. no. 2021113

EN

The paper presents the inverse method to estimate the sound power level of machines operated in industrial environments. Values of the partial sound power sources of machine components could be predicted based on the distribution of sound field parameters measured around the machine. Assigning partial sound power levels of machine components allows for the effective selection of efficient noise protection solutions for this machine. Measurements were carried out in an actual mechanical workshop. The multichannel measurement system for simultaneous recording of sound pressure levels and the angle of phase angle shift was used in measurements. Based on the determined the sound power of partial sources, the A-weighted sound pressure levels at the operator's workplace were determined.

6

Fluid dynamic and acoustic optimization methodology of a formula-student race car engine exhaust system using multilevel numerical CFD models

Mohamad Barhm, Ali Mohammed Qasim, Neamah Hayder Ahmed, Zelentsov Andrei, Amroune Salah

Diagnostyka

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2020

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Vol. 21, No. 3

103--111

EN

In this work a multilevel CFD analysis have been applied for the design of an engine exhaust system include manifold and muffler with improved characteristics of noise reduction and fluid dynamic response. The approaches developed and applied for the optimization process range from the 1D to fully 3D CFD simulation, exploring hybrid approaches based on the integration of a 1D model and 3D tools. Once the best configuration has been defined, the 1D-3D approach has been adopted to confirm the prediction carried out by means of the simplified approach, studying also the impact of the new configuration on the engine performances.

7

An Overview of the Noise Levels Measured in Industrial Facilities in Serbia and Implemented Methods of Protection

Luburić Uranija Kozmidis, Samardžić Selena, Lakatoš Robert, Mihailović Aleksandra, Veselinović Milka

Archives of Acoustics

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2020

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Vol. 45, No. 3

499--510

EN

Noise is one of the most significant factors which not only disturbs working conditions, but has a large impact on workers’ health. This problem has existed in industries since the beginning and, despite technical and other solutions, it has not been solved. There is a large number of papers, supported with very detailed analyses, that investigate noise levels in industry or contain questionnaires about the impact of noise on workers’ overall health and work abilities. The purpose of this paper is to contribute to the global picture of sustainability and the development of strategies for improving the quality of working environment, with special attention to the generation of noise in different production processes in thirteen different industries in Novi Sad, Serbia. The paper also seeks to examine the advantages and drawbacks of the implemented protective methods and to provide some recommendations for their better implementation in order to contribute to solving this significant problem of today.

8

Investigation of noise transmission of a machine tool enclosure

Bleicher Friedrich, Reichl Christoph, Linhardt Felix, Wimberger Peter, Habersohn Christoph, Krall Stephan

Journal of Machine Engineering

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2019

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Vol. 19, No. 3

5--16

EN

Machine tools are highly integrated mechatronic systems consisting of dedicated mechanic design and integrated electrical equipment – in particular drive systems and the CNC-control – to realize the complex relative motion of tool towards work piece. Beside the process related capabilities, like static and dynamic stiffness as well as accuracy behavior and deviation resistance against thermal influence, safety aspects are of major interest. The machine tool enclosure must fulfill multiple requirements like retention capabilities against the moving parts of broken tools, lose work pieces or clamping components. In regular use, the noise emission have to be inhibited at the greatest possible extent by the machine tool enclosure. Nevertheless, the loading door and the moving parts of the workspace envelope are interfaces where noise transmission is harder to be avoided and therefore local noise emissions increase. The aim of the objective investigation is to analyse the noise emission of machine tools to determine the local noise transmission of a machine tool enclosure by using arrays of microphones. By the use of this measuring method, outer surfaces at the front, the side and on the top of the enclosure have been scanned. The local transient acoustic pressures have been recorded using a standard noise source placed on the machine table. In addition, an exemplary manufacturing process has been performed to analyse the frequency dependent location resolved sound emissions.

9

Acoustic Analysis Using Sound Level Meter to Determine the Period of Usage of the Spindle Bearing of a Radial Drilling Machine

Charles S., Vijaya Joslin D.

Archives of Acoustics

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2019

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Vol. 44, No. 3

505--510

EN

The condition monitoring techniques like acoustic emission, vibration analysis, and infrared thermography, used for the failure diagnosis of bearings, require longer processing time, as they have to per form acoustical measurement followed by signal processing and further analysis using special software. However, for any bearing, its period of usage can be easily determined within an hour, by measuring the bearing sound, using sound level meter (SLM). In this paper the acoustical analysis of the spindle Bering of a radial drilling machine was performed using SLM, by measuring the sound pressure level of the bearing in decibels, for different frequencies, while muting all the other noises. Then using an experimental set up, two database readings were taken, one for new bearing and the other for completely damaged bearing, both are SKF6207, which itself is the spindle bearing. From these three sets of sound pressure level readings, the period of usage of the spindle bearing, was calculated using an interpolation equation, by substituting the life of the bearing from the manufacturer’s catalogue. Therefore, for any machine with a SKF6207 bearing, its usage time can be estimated using the database readings and one measurement on that machine, all with the same speed.

10

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.

11

Pomiary terenowe skuteczności niskiego betonowego ekranu akustycznego

Dulak L.

Materiały Budowlane

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2018

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nr 8

40--43

PL

W artykule przedstawiono wyniki skuteczności niskiego betonowego ekranu akustycznego wyznaczone w badaniach terenowych. Wyniki pomiarów wskazują na konieczność poszukiwania alternatywnych dla PN-ISO 10847 [4] metod wyznaczania skuteczności ekranowania w przypadku specyficznych sytuacji w terenie.

EN

The article presents results of field measurements of insertion loss a low concrete noise barrier. For specific situations in the field, the measurement result smake it necessary to look for methods for determinig the insertion loss that are alternative to PN-ISO 10847 [4].

12

Experimental analysis of noise and vibration of a diesel engine

Kilikevičienė K., Fursenko A., Kilikevičius A., Vainorius D., Matijošius J., Rimkus A., Bereczky A.

Journal of KONES

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2018

|

Vol. 25, No. 1

225-232

EN

Noise and vibration of ignition compression engine is one of the most complicated fields to cope with since every mechanism that compose of the engine affect them separately. In this study, effect of diesel on engine noise and vibration has been studied on an unmodified compression ignition engine. Noise and vibration characteristic of a direct ignition engine, which was fuelled with diesel, were investigated. With the usage of equations obtained from regression analysis, estimation of engine characteristic fuelled with various biodiesels researches were carried out. Tests were conducted at fixed injection timing of diesel fuel. The first system is for diesel fuel injection; the second one is PFI (port-fuelled injection) and is used for injecting alcohol into the engine intake manifold. The engine applied to this study was a naturally aspirated, 3in-line, IVECO AIFO 8031 i06.05 diesel engine with direct injection. Experiments were conducted in a sound insulated room. For each experiment, vibration data gathered from the engine block with 3.2 kHz (for vibration) for 2 s and with 20 kHz sampling frequency for 0.320 s. All measurements were performed under conditions: angle 10; 4 different loads (4, 8, 12 and 20 kW).

13

Pomiary poziomu ciśnienia akustycznego w pasmach 1/3-oktawowych za pomocą smartfonów

Kozłowski E., Młyński R.

Przegląd Mechaniczny

|

2017

|

nr 10

54--56

PL

Coraz częściej smartfony stają się urządzeniami służącymi do pomiaru poziomu ciśnienia akustycznego. W pracy przeanalizowano, czy smartfony mogą być także użyte jako urządzenia wspomagające dobór ochronników słuchu. Przeprowadzono pomiary poziomu ciśnienia akustycznego w pasmach 1/3-oktawowych za pomocą trzech modeli smartfonów. W badaniach tych korzystano zarówno z wewnętrznych mikrofonów wbudowanych w smartfony, jak również z mikrofonu zewnętrznego dołączanego do smartfonów za pomocą gniazda „jack”. Otrzymane wartości poziomu ciśnienia akustycznego w pasmach 1/3-oktawowych porównano z pomiarami odniesienia przeprowadzonymi z wykorzystaniem miernika poziomu dźwięku. Porównanie to wskazuje, że występują pewne różnice pomiędzy wynikami pomiarów otrzymanych za pomocą smartfonu i miernika poziomu dźwięku. Jednakże po zastosowaniu odpowiedniej korekcji istnieje możliwość stosowania smartfonów jako urządzeń wspomagających dobór ochronników słuchu.

EN

More and more often, smartphones are used to measure sound pressure levels. The work has analyzed whether smartphones can also be used to selection of hearing protectors. Sound pressure levels in 1/3-octave bands were measured using three smartphone models. Both internal microphones built into smartphones as well as an external microphone attached to smartphones using the jack connector were used. The obtained values of the sound pressure level in the 1/3-octave bands were compared with reference measurements made using the sound level meter. This comparison indicates that there are some differences between the measurement results obtained with the smartphone and the sound level meter. However, after applying the correction, there is possible to use smartphones to selection of hearing protectors.

14

A Fast Method of Feature Extraction for Lowering Vehicle Pass-By Noise Based on Nonnegative Tucker3 Decomposition

Wang H., Cheng G., Deng G., Li X., Li H., Huang Y.

Archives of Acoustics

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2017

|

Vol. 42, No. 4

619--629

EN

Usually, the judgement of one type fault of vehicle pass-by noise is difficult for engineers, especially when some significant features are disturbed by other interference noise, such as the squealing noise is almost simultaneous with the whistle in the exhaust system. In order to cope with this problem, a new method, with the antinoise ability of the algorithm on the condition by which the features are entangled, is developed to extract clear features for the fault analysis. In the proposed method, the nonnegative Tucker3 decomposition (NTD) with fast updating algorithm, signed as NTD_FUP, can find out the natural frequency of the parts/components from the exhaust system. Not only does the NTD_FUP extract clear features from the confused noise, but also it is superior to the traditional methods in practice. Then, an aluminium-foil alloy material, which is used for the heat shield for its lower noise radiation, replaces the aluminium alloy alone. Extensive experiments show that the sound pressure level of the vehicle pass-by noise is reduced 0.9 dB(A) by the improved heat shield, which is also considered as a more lightweight design for the exhaust system of an automobile.

15

Effect of Urethane Foam Cushioning on Structure-Borne Sound Transfer by a Slab with Panel Flooring

Mu R., Toyoda M., Takahashi D.

Archives of Acoustics

|

2016

|

Vol. 41, No. 1

99--106

EN

Urethane foam mattresses are commonly used as cushioning when placing panel flooring on the floor slab of a building. Urethane foam consists of elastic fibres with pores. Both elements can affect the performance of the insulation against impact sounds. However, these effects have not yet been detailed, and they may change if the material properties or constitution of the fibres and pores in the cushioning change. In this paper, we propose an analytical model for use in evaluating the performance of insulation against floor impact sound. This model was used to examine the contribution of the pores versus the elastic fibres to wave transmissions from the flooring surface to the slab. The results reveal that the constitution of the foam (either open or closed cells of pores) and the thickness and hardness of the cushion layer strongly affect the sound insulation performance of the floor.

16

Analiza zmian poziomu ciśnienia akustycznego wrzeciona obrabiarki w strefie pracy operatora

Błasiak M., Mięsikowska M., Nowakowski Ł.

Mechanik

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2015

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R. 88, nr 8-9CD2

390--398

PL

Przedmiotem artykułu jest analiza zmian poziomu ciśnienia akustycznego w strefie prac operatora, które jest emitowane przez wrzeciono obrabiarki CNC pracujące bez obciążenia z różnymi prędkościami obrotowymi oraz podczas skrawania z prędkością 10 000 obr/min. Istotą przeprowadzonych badań było sprawdzenie, czy poziom hałasu emitowanego przez obrabiarkę CNC nie przekracza wartości dopuszczalnej. Wykonano je zgodnie z zapisem badania hałasu podanym w normie ISO 230-5 oraz z wykorzystaniem norm ISO 3744 i ISO 11203. Badania pokazały, że podczas głębszej obróbki materiału pojawiają się dźwięki o charakterze impulsowych. Poziom dźwięku wzrasta wówczas do wartości 92,2 dB, a więc na stanowisku pracy następuje przekroczenie dopuszczalnego poziomu dźwięku. Dla różnych prędkości obrabiarki poziom dźwięku A utrzymuje się na stałym poziomie: 71÷72 dB(A) – dla prędkości do 5000 obr/min, 80 dB(A) – dla wyższych prędkości.

EN

The subject of the study was to analyze sound pressure levels at the operator work area, emitted by a CNC machine tool working in different speeds of spindle and during process of cutting with a speed of 10,000 rev / min. The essence of the study was to find out if the noise level emitted by the CNC machine tool exceeds the acceptable sound level. The study was carried out according to the specified standards in documents ISO 230-5, ISO 3744 and ISO 11203 [set of standards]. Obtained results indicate the appearance of an impulse sound at a deeper treatment of the material-deeper cutting causes the appearance of impulse noise. Under such conditions, the sound level rises to the value of 92.2 dB, which indicates a sound level that exceeds the acceptable sound measure levels. A sound level for different speeds of the machine is maintained at a constant level row 71/72 dB(A) up to 5000 rev / min, and increases for higher speeds of the machine tool to the value of 80 dB(A).

17

Research of noise in tractor K700 cabin

Pobedin A. V., Dolotov A. A., Iskaliev A. I., Potapov P. V.

Journal of KONES

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2015

|

Vol. 22, No. 1

261--264

EN

This paper briefly describes method of noise-measuring tractor’s K700 cabin, obtained noise spectres were analysed and recommendations based on these results for noise decreasing in cabin K700 are proposed. Air noise penetrates into the tractor’s K700 cabin through panels, enclosures, apertures, chinks etc. Structural noise in the cabin is caused by vibrations transfer from sources along tractor frame through vibration isolators to cabin walls and carcass. At that, the main noise sources are engine case, air system, exhaust system, engine cooling system fan and also transmission case located under cabin floor. Every panel in the cabin has own intensity of sound waves radiation and thus contributes to forming of the sound field on the operator workspace. Therefore, it is important to know the sound pressure level near every panel into the cabin. It was state that at low frequencies, noise from left windshield prevails. In addition, in high frequencies bands the highest sound pressure issues from partition between engine area and cabin. Noise spectres have sound pressure peaks in bands with centre frequencies. Total noise level perceived by operator in tractor cabin is less during tractor motion on dirt road without aggregate than during its work with seeding machine on field prepared for winter grasp. At that, partition between engine area and cabin contributes greatly. Thus, for integrated noisiness, reducing in the tractor cabin sound isolation of partition between engine area and cabin should be increased and also sound isolation of windshields located closely to exhaust pipe has to be improved. To decrease low-frequency noise optimization of tractor cabin vibration isolation system need to be performed.

18

Nowe regulacje w zakresie akustyki budowlanej

Kłosak A. K.

Izolacje

|

2015

|

R. 20, nr 5

12--22

PL

W artykule omówiono najważniejsze normy z zakresu akustyki budynków. Podano główne zmiany wprowadzone w trakcie prac aktualizacyjnych wraz z zakładanymi wartościami parametrów.

EN

The article briefly discusses the most important of regulations in the field of acoustic properties of building. The main changes are presented that were made during the updating works, including the anticipated performance values.

19

Effects of Acoustic Treatment on Music Teachers’ Exposure to Sound

Kozłowski E., Młyński R.

Archives of Acoustics

|

2014

|

Vol. 39, No. 2

159--163

EN

In this study, music teachers’ exposure to sound was tested by measuring the A-weighted equivalent sound pressure level (SPL), the A-weighted maximum SPL and the C-weighted peak SPL. Measurements were taken prior to and after acoustic treatment in four rooms during classes of trumpet, saxophone, French horn, trombone and percussion instruments. Results showed that acoustic treatment affects the exposure of music teachers to sound. Daily noise exposure levels (LEX, 8 h) for all teachers exceeded a limit of 85 dB while teaching music lessons prior to room treatment. It was found that the LEX, 8 h values ranged from 85.8 to 91.6 dB. The highest A-weighted maximum SPL and C-weighted peak SPL that music teachers were exposed to were observed with percussion instruments (LAmax = 110.4 dB and LCpeak = 138.0 dB). After the treatments, daily noise exposure level decreased by an average of 5.8, 3.2, 3.0, 4.2 and 4.5 dB, respectively, for the classes of trumpet, saxophone, French horn, trombone and drums, and did not exceed 85 dB in any case.

20

Acoustic properties of small wind turbines

Szulczyk J., Cempel C.

Vibrations in Physical Systems

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2012

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Vol. 25

405--410

EN

The study of vibroacoustic properties of small wind turbines with a vertical axis laboratory test conditions used in the form of an anechoic chamber in the Acoustics Laboratory, Institute of Energy, Department of Heat in. Anechoic chamber design allowed the installation of a duct through which the airflow is adjusted by means of a centrifugal fan mounted at the inlet of the waveguide. The paper presents the identification of the acoustic parameters of acoustic small wind turbines with a vertical axis comprising: a) determination of sound power levels for different classes of frequency characteristics and test wind turbines work b) identification of the components of the spectrum frequency - amplitude associated mainly with turbine speeds and frequencies of their own, such as duct The result of research was to obtain input data to define a more dedicated to the identification of measurement noise and vibration characteristics of wind turbines such as the efficiency of vibroacoustic, cepstrum analysis or dimensional analysis.