Nauki Techniczne

Archives of Acoustics

Zawartość

Archives of Acoustics | 2014 | vol. 39 | No 3 |

Abstrakt

Professor Jerzy Sadowski – outstanding Polish scientist, a specialist in acoustics – construction, industrial, architectural and environmental – passed away on 28th July 2014. Professor Jerzy Sadowski was born on 18th December 1924 in Augustów, in northeastern Poland. In 1946 he commenced studies at the Gdańsk University of Technology – initially at the Faculty of Architecture, to switch later to the Faculty of Electrical Engineering. The life of Jerzy Sadowski as a student was as complicated as the post-war history of Poland. Due to his involvement in an activity of illegal student organization, he was expelled from the university in 1949, with a ban on any further tertiary education. The ban had been lifted after a certain time which allowed him to recommence further studies, this time at the Warsaw University of Technology the Faculty of Communications, where in 1952 he obtained the diploma and title of Master of Science and Engineer. He received a lot of help from Professor Ignacy Malecki, the nestor of Polish acoustics. This certainly contributed to kindling the young engineer’s interest in acoustics, as a field of both knowledge and very important practical applications.

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Abstrakt

The Committee on Acoustics of the Polish Academy of Sciences was founded in 1964 by the reso lution of the General Assembly of the Polish Academy of Sciences, within its Division of Engineering Sci ences (Division 4). The idea of creating the Committee was brought up by Professor Ignacy Malecki, a distinguished scientist, an academic teacher, and an internationally acclaimed authority on acoustics.

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Abstrakt

Virtual Reality (VR) systems are used in engineering, architecture, design and in applications of biomedical research. The component of acoustics in such VR systems enables the creation of audio-visual stimuli for applications in room acoustics, building acoustics, automotive acoustics, environmental noise control, machinery noise control, and hearing research. The basis is an appropriate acoustic simulation and auralization technique together with signal processing tools. Auralization is based on time-domain modelling of the components of sound source characterization, sound propagation, and on spatial audio technology. Whether the virtual environment is considered sufficiently accurate or not, depends on many perceptual factors, and on the pre-conditioning and immersion of the user in the virtual environment. In this paper the processing steps for creation of Virtual Acoustic Environments and the achievable degree of realism are briefly reviewed. Applications are discussed in examples of room acoustics, archeological acoustics, aircraft noise, and audiology.

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Abstrakt

Gas bubbles in the ocean are produced by breaking waves, rainfall, methane seeps, exsolution, and a range of biological processes including decomposition, photosynthesis, respiration and digestion. However one biological process that produces particularly dense clouds of large bubbles, is bubble netting. This is practiced by several species of cetacean. Given their propensity to use acoustics, and the powerful acoustical attenuation and scattering that bubbles can cause, the relationship between sound and bub-ble nets is intriguing. It has been postulated that humpback whales produce ‘walls of sound’ at audio frequencies in their bubble nets, trapping prey. Dolphins, on the other hand, use high frequency acous-tics for echolocation. This begs the question of whether, in producing bubble nets, they are generating echolocation clutter that potentially helps prey avoid detection (as their bubble nets would do with man-made sonar), or whether they have developed sonar techniques to detect prey within such bubble nets and distinguish it from clutter. Possible sonar schemes that could detect targets in bubble clouds are proposed, and shown to work both in the laboratory and at sea. Following this, similar radar schemes are proposed for the detection of buried explosives and catastrophe victims, and successful laboratory tests are undertaken.

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Abstrakt

Limited Traffic Zone (LTZ) is a planning strategy that is more and more adopted by municipalities in Europe to improve their environmental conditions. It consists in the prohibition for traditional vehicles to circulate in specific areas. Although the main aim is to tackle air pollution problems, positive effects are registered in terms of reduction of noise annoyance and in terms of improved “quality of life” if specific conditions are respected. On the other side under the drive of the global market, the number of circulating electric vehicles in urban sites is also increasing. In the next years we expect to experience a new and not well-known urban soundscape.

In this paper is presented an overview of recent urban projects and policies that deal with noise control and how these experiences will match into the next years with the sound characteristics of new electric vehicles for private and public transportation.

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Abstrakt

The area of environmental protection concern minimises the impact that technical objects have on the environment. Usually the most effective way of protecting the environment is to influence the source of the problem. For this reason studies are conducted to modify the construction of machines, power machines in particular, so as to minimise their impact on the environment.

In the case of environmental protection from noise it is most convenient to carry out measurements in an anechoic chamber. Unfortunately, this is possible only in very limited circumstances. In all other cases measurements are performed using an engineering method or the survey method, both of which are described in the standards and by taking into account the so-called environmental corrections. The obtained results are burdened with greater error than those of measurements in an anechoic chamber. Therefore, it would seem advantageous to develop a method of obtaining similar and reliable results as those in an anechoic chamber, but in a reverberant field. The authors decided to use numerical modelling for this purpose.

The main objective of this work is a comprehensive analysis of the numerical model of a laboratory designed for acoustic tests of selected power machines. The geometry of a room comprising an area of analysis is easy to design. The main difficulty in modelling the phenomena occurring in the analysed area can be the lack of knowing the boundary conditions. Therefore, the authors made an attempt to analyse the sensitivity of various acoustic parameters in a room in order to change these boundary conditions depending on the sound absorption coefficient

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Abstrakt

Airborne acoustic properties of composite structural insulated panels CSIPs composed of fibre-magnesium-cement facesheets and expanded polystyrene core were studied. The sound reduction ratings were measured experimentally in an acoustic test laboratory composed of two reverberation chambers. The numerical finite element (FEM) model of an acoustic laboratory available in ABAQUS was used and verified with experimental results. Steady-state and transient FE analyses were performed. The 2D and 3D modelling FE results were compared. Different panel core modifications were numerically tested in order to improve the airborne sound insulation of CSIPs.

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Abstrakt

In this work, simulation techniques have been implemented to study the sound fields of a multi-configurable performance enclosure by creating computer acoustic 3D-models for each room configuration. The digital models have been tuned by means of an iterative fitting procedure that uses the reverberation times measured on site for unoccupied conditions with the orchestra shell on the stage. The initial virtual acoustic model is validated by comparing the other monaural and binaural acoustic parameters measured in the room in terms of their perception differential threshold. The procedure is applied to the Maestranza Theatre of Seville, built for the Universal Exhibition in 1992. The spatial distribution of the acoustic parameters in the audience area of the venue by measured parameters and simulation mappings enables the establishment of three zones of acoustic comfort, and are corroborated by the values of the Ando-Beranek function which provide a global quality coefficient of each zone.

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Abstrakt

It is assumed in the paper that the signals in the enclosure in a transient period are similar to a noise induced by vehicles, tracks, cars, etc. passing by. The components of such signals usually points out specific dynamic processes running during the observation or measurements. In order to choose the best method of analysis of these phenomena, an acoustic field in a closed space with a sound source inside is created. Acoustic modes of this space influence the sound field. Analytically, the modal analyses describe the above mentioned phenomena. The experimental measurements were conducted in the room that might comprise the closed space with known boundary conditions and the sound source Brüel & Kjær Omni-directional type 4292 inside. To record sound signals before the field's steady state was reached, the microphone type 4349 and the 4-channel frontend 3590 had been used. The obtained signals have been analysed by using two approaches, i.e. Fourier and the wavelet analysis, with the emphasis on their efficiency and the capability to recognise important details of the signal. The results obtained for the enclosure might lead to the formulation of a methodology for an extended investigation of a rail track or vehicles dynamics.
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In the acoustic fatigue experiment for hypersonic vehicle in simulated harsh service environment on ground, acoustic loads on the surface of test pieces of the vehicle need to be measured. However, for the normal microphones without high temperature resistance ability, the near field sound measurement cannot be achieved. In this work, on the basis of previous researches, an acoustic tubes array is designed to achieve the near field measurement of acoustic loads on the surface of the test piece in the supersonic airflow with high temperature achieved by coherent jet oxygen lance. Firstly, the process of designing this acoustic tubes array is introduced. Secondly, the equality of phase differences at the front and at the end of the tubes is stated and proved using a phase differences test with an acoustic tubes array whose design is presented in this text; therefore, the phase differences of signals acquired by microphones can be directly applied to beamforming algorithm to determine the acoustic load source. Finally, using above mentioned acoustic tubes array, measurement of acoustic load, with and without a test piece in the supersonic airflow made by the coherent jet oxygen lance, is conducted respectively, and the measurements results are analyzed.
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Standing waves and acoustic heating in a one-dimensional resonator filled with chemically reacting gas, is the subject of investigation. The chemical reaction of A → B type, which takes place in a gas, may be reversible or not. Governing equations for the sound and entropy mode which is generated in the field of sound are derived by use of a special mathematical method. Under some conditions, sound waves propagating in opposite directions do not interact. The character of nonlinear dynamics of the sound and relative acoustic heating or cooling depends on reversibility of a chemical reaction. Some examples of acoustic heating in a resonator are illustrated and discussed.
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Abstrakt

Reverberation is a common problem for many speech technologies, such as automatic speech recognition (ASR) systems. This paper investigates the novel combination of precedence, binaural and statistical independence cues for enhancing reverberant speech, prior to ASR, under these adverse acoustical conditions when two microphone signals are available. Results of the enhancement are evaluated in terms of relevant signal measures and accuracy for both English and Polish ASR tasks. These show inconsistencies between the signal and recognition measures, although in recognition the proposed method consistently outperforms all other combinations and the spectral-subtraction baseline.
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Abstrakt

The reviewed book is a new, expanded and modernized edition of the classical position of the book “Acoustics” published in 1954 and reprinted in 1986. The subtitle: “Sound Fields and Transducers” reflects well the nature of the changes in relation to the original. The chapters concerning sound fields and transducers have been added or significantly expanded and chapters on other subjects, such as noise control, hearing, and speech, have been removed. The chapter about acoustic measurements has been also removed, although some parts of it concerning reciprocity calibration of transducers would be compatible with the concept of the present version of the book. The book consists of 14 chapters. The chapters are divided into parts which are numbered consecutively, independently on numeration of chapters, and sections numbered within chapters. The book contains also three appendices. The scientific level of the book is high and it is designed for advanced readers, e.g., graduate students, and professionals who want to expand their knowledge.
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Redakcja

Editorial Board
Editor-in-Chief
Andrzej Nowicki (Institute of Fundamental Technological Research PAN, Warszawa)
Deputy Editor-in-Chief
Barbara Gambin (Institute of Fundamental Technological Research PAN, Warszawa)
Associate Editors
Genaral linear acoustics and physical acoustics
• Wojciech P. Rdzanek (University of Rzeszów, Rzeszów)
• Anna Snakowska (AGH University of Science and Technology, Kraków)
Architectural acoustics
• Tadeusz Kamisiński (AGH University of Science and Technology, Kraków)
Musical acoustics and psychological acoustics
• Andrzej Miśkiewicz (The Fryderyk Chopin University of Music, Warszawa)
• Anna Preis (Adam Mickiewicz University, Poznań)
Underwater acoustics and nonlinear acoustics
• Grażyna Grelowska (Gdańsk University of Technology, Gdańsk)
Speech, Computational acoustics and signal processing
• Ryszard Gubrynowicz (Polish-Japanese Institute of Information Technology, Warszawa)
Ultrasonics, transducers and instrumentation
• Krzysztof Opieliński (Wrocław University of Technology, Wrocław)
Electroacoustics
• Jan Żera (Warsaw University of Technology, Warszawa)
Noise control and environmental acoustics
• Jan Adamczyk (AGH University of Science and Technology, Kraków)
• Mirosław Meissner (Institute of Fundamental Technological Research PAN, Warszawa)
• Janusz Kompała (Central Mining Institute, Katowice)
Secretary
• Izabela Ewa Mika

Kontakt

Archives of Acoustics
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Instrukcje dla autorów

Author Guidelines
• Manuscripts intended for publication in Archives of Acoustics should be submitted in pdf format by an on-line procedure.
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• Detailed information see Article Requirements.
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o why the paper is submitted to ARCHIVES OF ACOUSTICS,
o suggestion on the field of acoustics related to the topic of the submitted paper,
o the statement that the manuscript is original, the submission has not been previously published, nor was sent to another journal for consideration,
o 3–5 names of suggested reviewers together with their affiliations, full postal and e-mail addresses; at least 3 suggested reviewers should be affiliated with other scientific institutions than the affiliations of the authors,
o author’s suggestion to classification of the paper as the research paper, review paper or technical note.

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For more information on references see http://acoustics.ippt.gov.pl/public/Instructions.pdf.
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