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    Wyświetlanie 1-14 z 14
    Tytuł:
    Effects of Acoustic Treatment on Music Teachers’ Exposure to Sound
    Autorzy:
    Kozłowski, E.
    Młyński, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/177728.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    music teachers
    sound pressure level
    acoustic treatment
    Opis:
    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.
    Źródło:
    Archives of Acoustics; 2014, 39, 2; 159-163
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sound Radiation by a Cylindrical Open Cavity with a Surface Source at the Bottom
    Autorzy:
    Szemela, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/176682.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    open cylindrical cavity
    sound pressure
    sound power
    continuity conditions
    Opis:
    The rigorous solution describing the sound radiation by an arbitrary surface source located at the bottom of a cylindrical open cavity embedded in a flat baffle has been obtained. The open cavities of different shapes can be found in some architectural structures as well as are components of sensors, musical instruments and vehicles. The presented formulas have been expressed in the form of Infinite sums. To use them, the infinite sums have to be truncated to the finite number of terms. Therefore, in practice, the results obtain based on the proposed solution are not exact and their accuracy is determined by the truncation error. The use of presented formulas is an alternative method for the finite element method (FEM). However, taking into account that the calculation efficiency of FEM rapidly decrease when a volume of considered region increases, the obtained in this study solution can be more useful in some practical cases. The approximated formula of a high computational efficiency has been presented for the sound pressure in the far field. The sound radiation has been analyzed for a rectangular piston as a sound source. The influence of cavity depth ratio on the radiation efficiency has been investigated. The cases for which the cavity radiation efficiency can be approximately calculated from the formula valid for a baffled sound source have been determined.
    Źródło:
    Archives of Acoustics; 2018, 43, 1; 49-60
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Technical Possibilities of Reducing the Sound Pressure Level Emitted into the Environment by a Power Transformer
    Autorzy:
    Borucki, S.
    Boczar, T.
    Cichoń, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/177473.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    power transformer
    corrected sound pressure level
    noise
    modernization
    Opis:
    The subject presented in this paper refers to measurements and assessment of the corrected sound pressure level values (noise) occurring around a medium-power transformer. The paper presents the values of noise accompanying the operation of the power object before and after its modernization, which consisted in repeated core pressing and replacement of the cooling system. The main aim of the research work was the assessment of the influence of the repair work on the noise level emitted into the environment.
    Źródło:
    Archives of Acoustics; 2011, 36, 1; 49-56
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis and Optimization of Micro Speaker-Box Using a Passive Radiator in Portable Device
    Autorzy:
    Jiang, Y.-W.
    Kwon, J.-H.
    Kim, H.-K.
    Hwang, S.-M.
    Powiązania:
    https://bibliotekanauki.pl/articles/176530.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    passive radiator
    speaker box
    SPL improvement
    Sound Pressure Level
    Opis:
    With the rapid development of multimedia devices such as smart phones and tablet PCs, microspeakers have been recently increasingly used for audio equipment. Improving the acoustic performance of a microspeaker is always a main concern, especially in the low frequency range. To avoid sound cancelation, a microspeaker unit is usually inserted into a speaker box. A passive radiator is also used in speaker boxes to improve the sound performance in the loudspeaker system. However, passive radiators have not been applied into microspeaker system. In this study, a speaker box with a passive radiator was analyzed and optimized to achieve a higher Sound Pressure Level (SPL) in a microspeaker system. The Finite Element Method (FEM), two-degree-of-freedom (DOF) vibration theory, and a plane circular piston sound source were used to study the electromagnetic, vibration, and acoustic characteristics, respectively. Optimization was conducted by changing the mass, stiffness, and size of the passive radiator. Based on the optimized parameters, a new sample was manufactured. The experiment results show that the SPL of the optimized speaker box with a passive radiator is improved by 5 dB at 200 Hz compared with the one without a radiator. The analysis results also matched the experiment results.
    Źródło:
    Archives of Acoustics; 2017, 42, 4; 753-760
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A Fast Method of Feature Extraction for Lowering Vehicle Pass-By Noise Based on Nonnegative Tucker3 Decomposition
    Autorzy:
    Wang, H.
    Cheng, G.
    Deng, G.
    Li, X.
    Li, H.
    Huang, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/177883.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    vehicle pass-by noise
    NTD
    feature extraction
    sound pressure level
    Opis:
    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.
    Źródło:
    Archives of Acoustics; 2017, 42, 4; 619-629
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Urethane Foam Cushioning on Structure-Borne Sound Transfer by a Slab with Panel Flooring
    Autorzy:
    Mu, R.
    Toyoda, M.
    Takahashi, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/176817.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    urethane foam
    direct pasted flooring
    floor impact sound
    sound pressure level
    sound insulation performance
    Opis:
    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.
    Źródło:
    Archives of Acoustics; 2016, 41, 1; 99-106
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sound Radiation from a Surface Source Located at the Bottom of the Wedge Region
    Autorzy:
    Szemela, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/176912.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    wedge region
    sound pressure
    sound power
    Neumann boundary value problem
    Helmholtz equation
    vibrating piston
    Hankel transform
    Opis:
    Applying rigorous analytical methods, formulas describing the sound radiation have been obtained for the wedge region bounded by two transverse baffles with a common edge and bottom. It has been assumed that the surface sound source is located at the bottom. The presented formulas can be used to calculate the sound pressure and power inside the wedge region. They are valid for any value of the wedge angle and represent a generalization of the formulas describing the sound radiation inside the two and three-wall corner region. Moreover, the presented formulas can be easily adapted for any case when more than one sound source is located at the bottom. To demonstrate their practical application, the distribution of the sound pressure modulus and the sound power have been analyzed in the case of a rectangular piston located at the wedge’s bottom. The influence of the transverse baffle on the sound power has been investigated. Based on the obtained formulas, the behaviour of acoustic fields inside a wedge can be predicted.
    Źródło:
    Archives of Acoustics; 2015, 40, 2; 223-234
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    3D Multi-Domain MFS Analysis of Sound Pressure Level Reduction Between Connected Enclosures
    Autorzy:
    Godinho, L.
    Branco, F. G.
    Mendes P., A.
    Powiązania:
    https://bibliotekanauki.pl/articles/177013.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Method of Fundamental Solutions (MFS)
    domain decomposition
    closed spaces
    sound pressure level reduction
    Opis:
    In this paper, the authors study the 3D propagation of sound waves between two closed spaces. The separation element between the two rooms is considered to include either a small opening or a homogeneous lightweight panel, coupling the two spaces. A numerical study of this configuration is performed, trying to understand the influence of the position and geometry of this opening in the sound pressure level reduction curve at low and midfrequencies. Additionally, the coupling effect between the two acoustic spaces is analyzed, in order to better understand its importance when determining the sound pressure level reduction. Different boundary conditions are ascribed to the walls of these rooms, simulating both the completely reflecting and partially absorbing surfaces. The numerical modelling was performed using a multi-domain formulation of the Method of Fundamental Solutions (MFS). The system is composed of two coupled rooms, limited by rigid or by absorbing walls, and separated by a thin wall (tending to null thickness) with a small opening. An experimental validation of the proposed model is presented, comparing its results with those found experimentally for a reduced-scale model. It is important to note that, for such a configuration, a traditional single-domain approach using methods like the MFS or the BEM would lead to undetermined equation systems, and thus the proposed model makes use of a domain decomposition technique.
    Źródło:
    Archives of Acoustics; 2011, 36, 3; 575-601
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation and Analysis of Environmental Noise Pollution in Seven Major Cities of India
    Autorzy:
    Garg, N.
    Sinha, A. K.
    Dahiya, M.
    Gandhi, V.
    Bhardwaj, R. M.
    Akolkar, A. B.
    Powiązania:
    https://bibliotekanauki.pl/articles/177396.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    NANMN
    National Ambient Noise Monitoring Network
    day equivalent level
    Lday
    night equivalent level
    Lnight
    day-night average sound level
    Ldn
    equivalent continuous sound pressure level
    LAeq,24h
    Opis:
    The paper describes the noise monitoring data acquired from the pilot project on the establishment of National Ambient Noise Monitoring Network (NANMN) across seven major cities in India for continuous noise monitoring throughout the year. The annual average Lday (06–22 h) and Lnight (22–06 h) values observed in year 2011–2014 for the 35 locations under study in which 14 locations are in commercial zone, 5 in Industrial, 7 in residential and 9 in silence zones are described. The long-term noise monitoring shows that ambient noise levels have marginally increased for 29 sites (82.9%) since past four years. The present study is focused on evaluation and analysis of environmental noise pollution at 35 noise monitoring sites in seven major cities of India and shall be instrumental in planning for the noise abatement measures for controlling the noise pollution in these sites.
    Źródło:
    Archives of Acoustics; 2017, 42, 2; 175-188
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Impact of gear rim narrowing angle on the temperature and sound pressure of Beveloid gear pair made of polymeric materials
    Autorzy:
    Strojny, Piotr
    Powiązania:
    https://bibliotekanauki.pl/articles/2086844.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    helical transmissions
    operation
    polymeric materials
    sound pressure
    operating temperature of a Beveloid gear pair
    przekładnie śrubowe
    operacja
    materiały polimerowe
    ciśnienie akustyczne
    temperatura robocza pary przekładni Beveloid
    Opis:
    The paper contains a description of the geometry of Beveloid gears. It describes the distribution of forces in a Beveloid gear with a straight tooth line and a helical tooth line. The paper presents research on the experimentally determined parameters of transmission operation, including the sound pressure level and the amount of heat emitted during operation. The design and construction of the test stand were presented. The research methodology was described. Operational tests are carried out on household appliances with Beveloid gears: Grinder and Jam mixer. Thanks to an appropriately selected narrowing angle, estimated values of service life extension of the above-mentioned transmissions are given.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 5; e138818, 1--10
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modified pressure-pressure sound intensity measurement method and its application to loudspeaker set directivity assessment
    Autorzy:
    Mickiewicz, Witold
    Raczyński, Michał
    Powiązania:
    https://bibliotekanauki.pl/articles/220959.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    sound intensity
    pressure-pressure intensity probe
    loudspeaker set measurements
    Opis:
    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.
    Źródło:
    Metrology and Measurement Systems; 2020, 27, 1; 181-194
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Acoustic Nonlinearity Parameter B/A, Internal Pressure, and Acoustic Impedance Determined at Pressures up to 100 MPa for 1-Ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide
    Autorzy:
    Zorębski, E.
    Zorębski, M.
    Dzida, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/177585.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    nonlinearity parameter
    speed of sound
    high pressure
    ionic liquids
    internal pressure
    Opis:
    The nonlinearity parameter B/A, internal pressure, and acoustic impedance are calculated for a room temperature ionic liquid, i.e. for 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide for temperatures from (288.15 to 318.15) K and pressures up to 100 MPa. The B/A calculations are made by means of a thermodynamic method. The decrease of B/A values with the increasing pressure is observed. At the same time B/A is temperature independent in the range studied. The results are compared with corresponding data for organic molecular liquids. The isotherms of internal pressure cross at pressure in the vicinity of 70 MPa, i.e. in this range the internal pressure is temperature independent.
    Źródło:
    Archives of Acoustics; 2016, 41, 1; 59-66
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Can DIPPR Database be Used for an Estimation of the Speed of Sound? A Case Study of Liquid Hydrocarbons
    Autorzy:
    Postnikov, E. B.
    Powiązania:
    https://bibliotekanauki.pl/articles/177811.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    speed of sound
    DIPPR
    reduced bulk modulus
    internal pressure
    Opis:
    The paper analyses a possibility of utilising the information which is contained in DIPPR database for a calculation of the speed of sound, which is absent there. As an example, liquid hydrocarbons are considered: n-hexane, 1-hexene, cyclohexane, cyclohexene, benzene, and 1-hexanols, as well as representatives of n-alkanes with various hydrocarbon chain lengths. It is shown that the Brelvi-O’Connell correlation for the reduced bulk modulus, supplied with the correlations for the internal pressure at the normal boiling temperature, results in the values having accuracy comparable with other DIPPR data for the region below the boiling point bounded by the values of the reduced density around pr ≈ 3.5. The source of errors originated from the Brelvi-O’Connell correlation for larger reduced densities is discussed.
    Źródło:
    Archives of Acoustics; 2016, 41, 4; 713-719
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sound Radiation from a Roundabout
    Autorzy:
    Piddubniak, O.
    Piddubniak, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/177962.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    roundabout
    car sound radiation
    stationary phase method
    acoustic pressure
    power flow density
    Opis:
    Sound propagation from the vehicles moving on the city roundabout, with taking into account the wind is investigated. Solution of the problem for one moving sound source is found by means of the integral Fourier transforms extended over space variables and time. Inverse transforms are calculated approximately, using a stationary phase method and iterative technique. The solution for a general problem is obtained as a superposition of many partial solutions. The numerical analysis of noise characteristics is performed for the three-way Korfanty roundabout case in Łódz.
    Źródło:
    Archives of Acoustics; 2010, 35, 3; 437-456
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-14 z 14

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