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Number of results: 96
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Abstract

Acoustical attenuation spectra in the frequency range 12 kHz - 2 GHz and nonequilibrium time domain measurements are briefly reviewed for aqueous solutions of various mono- and disaccharides as well as alkyl glycosides. Several relaxation regimes emerge with relaxation times between 10-11 s and 103 s. In this paper relaxation terms reflecting conformational changes are discussed, particularly mutarotation (103 s), chair-chair ring inversion (1 μs), two modes of pseudorotation (100 ns, 10 ns), disaccharide ring isomerisation (10 ns), and exocyclic side group rotation (1 ns).
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Abstract

Results from broadband acoustical spectroscopy for aqueous solutions of mono- and disaccharides with salts added, of various alkyl glycosides, and of α-cyclodextrin with n-octyl-β-D-glucopyranoside added are briefly summarized in view of their relevance in the study of molecular association and complexation processes. Mono- and tridentate complexes of alkali earth ions with saccharides are discussed as well as the monomer exchange between micellar structures and the suspending phase in the alkyl glycoside surfactant solutions. Particular attention is given to the behaviour at solute concentrations close to the critical micelle concentration or aggregate concentration, respectively. Also described is the competition between inclusion complex formation and self-aggregation in solutions containing cyclodextrin and alkyl glycoside surfactant.
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Abstract

The following paper presents an idea of minimising the number of connections of individual piezoelectric transducers in a row-column multielement passive matrix system used for imaging of biological media structure by means of ultrasonic projection. It allows to achieve significant directivity with acceptable input impedance decrease. This concept was verified by designing a model of a passive ultrasonic matrix consisting of 16 elementary piezoceramic transducers, with electrode attachments optimised by means of electronic switches in rows and columns. Distributions of acoustic field generated by the constructed matrix model in water and results of the calculations conformed well.
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Abstract

This article presents the results of experimental studies of simultaneous transmission of ultrasonic waves and laser signals in optical fibers by the use of both the optical single mode and multimode fiber couplers. This work was aimed, among other things, at the study of the way the acoustic energy affects a laser beam. The light wave was guided into one of the coupler's arms. The optical power applied to one input of the coupler is separated into two coupler outputs according to the rate determined by the coupling coefficient. Only an ultrasonic wave generated by a sandwich type transducer is applied to the other arm of the coupler. In this experiment, as in case of the light wave, the acoustic power is separated into both the outputs. One can observe the interaction of both the waves on the two outputs - a modulation of the light wave by means of the ultrasonic wave is possible. The output signal was detected using a PIN diode and an optical power meter (OPM). Temporary courses were observed on an oscilloscope screen. The simultaneous transmission of ultrasounds and optical radiation in optical fibers can be used in the construction of medical equipment.
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Abstract

Noise Control is the most important international acoustics conference regularly organized in Poland. The XV International Conference Noise Control 2010 is taking place between June 6 and 9, 2010, in Ksi?? in Wa?brzych. It is organized by the Central Institute for Labour Protection - National Research Institute, the Committee on Acoustics of the Polish Academy of Sciences, the Polish Acoustical Society, with the cooperation of the Department of Mechanics and Vibroacoustics of the AGH University of Science and Technology, the Department of Acoustics of the Building Research Institute and the Chair of Acoustics of the Wroc?aw University of Technology.
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Abstract

In the article a short historical outline of noise control conferences organized in Poland is given. Those conferences with the participation of Polish specialists have been organized since 1964; since 1976 they have been evolved into International Noise Control Conferences. Silhouettes of four Polish scientists, which have made a large contribution to the noise and vibration control in Poland, are presented. Also the current state of threats by noise and vibrations have been briefly mentioned. The significance of such conferences has been emphasized.
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Abstract

This paper presents the interior acoustical characterization of the 9,000-seat church of the Holy Trinity in the Sanctuary of Fátima, Portugal, inaugurated in 2007. In situ measurements were held regarding interior sound pressure levels (with and without the HVAC equipment working), NC curves, RASTI (with and without the installed sound system) and reverberation time. The results are presented and commented according to the design values. A comparison is made with other churches in the world, also with a very large volume (for instance the Basilica Mariacka in Gdańsk). The measured data are also used to calculate a global index of this church acoustic quality using Engel's and Kosała's Index Method.
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Abstract

The physical phenomena occurring in sound-absorbing and insulating enclosures are subject of the present paper. These phenomena are: absorption in air and by the sound-absorbing material covering the walls and the coincidence effect. The absorption in the air can be neglected in small size enclosures for low ultrasonic frequencies (20-30 kHz). The coincidence plays a role in decrease of the sound insulation, however the main role play the leaks. The boards made of ceramic fibers have been chosen as the optimal sound-absorbing material. They are dense and have deeply porous structures. The enclosure for insulation of 20-kHz noise produced by a welding machine has been designed and manufactured, and reductions of 25 dB of peak and Leq levels have been achieved.
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Abstract

Traditionally I invite you to acquaint with preliminary program and some abstracts of lectures submitted to presentation in 38th Winter School on Vibroacoustical Hazards Suppressions. This national School, organized by Upper Silesian Division of the Polish Acoustical Society and Institute of Physics at Silesian University of Technology, at this year is planned at the first week of March 2010. This conference is organized in different places of Silesian Beskidy Mountains, but this year it is organized in Szczyrk. The conference is the forum for all environmental vibroacoustics fields. Particularly it concern to traffic noise, industry noise, vibroacoustics of machines, room acoustics, noise protection and similar problems. During the School the theoretical works, experimental, measuring, technical, applied and normative ones are presented. The School lectures, and other conference materials, will be published in the "Materials of the XXXVIII Winter School on Vibroacoustical Hazards Suppressions" (in Polish) edited by Dr. Roman Bukowski and Dr. Mieczys?aw Roczniak (chairman of the conference). This publication is intend to participants of the School and for many libraries in Poland.
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Abstract

I have a great pleasure to inform the "AA" Readers that the 39th Winter School on Wave and Quantum Acoustics, organized by Upper Silesian Division of the Polish Acoustical Society and Institute of Physics at Silesian University of Technology, is planned at the top of March 2010 in beautiful scenery of Silesian Beskidy Mountains. Many times it was organized in Wisła, Skoczów, Szczyrk, and Korbielów, and this year it will be organized again in Szczyrk. As always, the School has been a place where achievements of various sections of physical acoustics (especially molecular acoustics, quantum acoustics, acousto-optics, magnetoacoustics, acoustoelectronics, photoacoustics, acoustics of solids etc.) are being exchanged. Moreover, some similar and related topics, for example optoelectronics and thermal wave methods, will be presented too. As at previous years the School will be divided on three different, but complementary, parts - Winter Workshops (WW). Chronologically it will be: 6th WW on Acoustoelectronics (chairman Prof. Marian Urbanczyk, Silesian University of Technology, Gliwice), 6th WW on Molecular Acoustics, Relaxation and Calorimetric Methods (chairwoman Dr. Marzena Dzida, Silesian University of Technology, Katowice) and 15th WW on Photoacoustics and Thermal Waves Methods (chairman Prof. Jerzy Bodzenta, Silesian University of Technology, Gliwice). Moreover, this year we propose take participation in associated conference - the 4th conference on Integrated Optics - Sensors, Sensing Structures and Methods (chairman Prof. Tadeusz Pustelny, Silesian University of Technology, Gliwice).
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Abstract

In recent years the application of computer software to the learning process has been found to be an indisputably effective tool supporting the traditional teaching methods. Particular focus has been put on the application of techniques based on speech and language processing to the second language learning. Most of the commercial self-study programs, however, do not allow for introduction of an individualized learning course by the teacher and to concentrate on segmental features only. The paper discusses the use of speech technology in the training of foreign languages' pronunciation and prosody and defines pedagogical requirements for an effective training with CAPT systems. In this context, steps taken in the development of the intelligent tutoring system AzAR3.0 (German ‘Automat for accent reduction’) in the scope of the Euronounce project (Cylwik et al., 2008) are described with the focus on creation of the linguistic content. In response to the European Union's call for promoting less widely spoken languages, the project focuses on German as a target language for native speakers of Polish, Slovak, Czech, and Russian, and vice versa. The paper presents the design of the speech corpus for the purpose of the tutoring system and the analysis of pronunciation errors. The results of the latter provide information which is important for Automatic Speech Recognition (ASR) training on the one hand, and for automatic error detection and feedback generation on the other hand. In the end, Pitch Line software for implementation in the prosody visualization and training module of AzAR3.0 tutoring system is described.
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Abstract

Absolute pitch is a unique feature of the auditory memory which makes it possible for its possessors to recognize the musical name (chroma) of a tone. Six musicians with absolute pitch, selected from a group of 250 music students as best scoring in musical pitch-naming tests, identified the chroma of residue pitch produced by harmonic complex tones with several lower partials removed (residual sounds). The data show that the percentage of correct chroma recognitions decreases as the lowest physically existent harmonic in the spectrum is moved higher. According to our underlying hypothesis the percentage of correct chroma recognitions corresponds to the pitch strength of the investigated tones. The present results are compared with pitch strength values derived in an experiment reported by Houtsma and Smurzynski (1990) for tones same as those used in this study but investigated with the use of a different method which consisted in identification of musical intervals between two successive tones. For sounds comprising only harmonics of very high order the new method yields a very low pitch recognition level of about 20% while identification of musical intervals remains stable at a level of about 60%.
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Abstract

The aim of this project was to create a ranking of the nursery schools in Wrocław with regard to the quality of the acoustic environment on their premises, using a specially developed evaluation methodology. Each nursery school was rated according to an adopted grading scale on the basis of the noise level distribution on the playground and on the nursery school building facades. Using the grading scale one can classify nursery school premises into twelve categories characterized by different acoustic environment quality, from exceptionally good (< 45 dB) to exceptionally bad (> 70 dB). The appropriately rescaled data from the acoustic map of Wrocław and the authors' own measurements and simulation analyses were used. The developed methodology was verified by comparing the ratings yielded by it with those determined on the basis of field measurements and simulation studies, carried out for several selected nursery schools. The paper presents the results of an acoustic environment quality assessment carried out, using the developed investigative methodology, for 118 nursery schools located in Wrocław.
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Abstract

In the last years the number of new forms of workplaces, such as call centers, increases. It is defined as a workstation where the basic tasks of a worker are carried out with the use of a phone and a computer. According to statistics, about 1.3-4% of workers are employed in call centers in the European countries. The noise is one of the harmful and annoying hazards of call center workstations. The paper presents the noise sources in call center rooms, assessment criteria of noise and results of noise measurements in call center workstations. The results of measurements show that the noise at call center workstations (during the use of handset receiver phone by operators) can be harmful (causing the risk of hearing loss) and annoying, as it makes it difficult to carry out the basic work activities and causes additionally auditory disadvantageous changes in health.
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Abstract

An important aspect in assessing noise in urban agglomerations is the subjective one, which takes into account the sensitivity and specific reactions of residents to the noise in their living environment. This paper presents results of a sociological study initiated to determine the population awareness, regarding the urban acoustic environment and estimation of effects and disturbance. The survey was conducted in a Romanian city, to complement the information provided by the strategic noise map of the area. This approach allows the estimation of specific local patterns of reaction and response to urban noise of the exposed population and provides the information, needed to develop action plans and to set proper solutions for urban area planning.
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Abstract

In the paper the author has described the visualization methods in acoustic flow fields and show how these methods may assist scientists to gain understanding of complex acoustic energy flow in real-life field. A graphical method will be presented to determine the real acoustic wave distribution in the flow field. Visualization of research results, which is unavailable by conventional acoustics metrology, may be shown in the form of intensity streamlines in space, as a shape of floating acoustic wave and intensity isosurface in three-dimensional space. In traditional acoustic metrology, the analysis of acoustic fields concerns only the distribution of pressure levels (scalar variable), however in a real acoustic field both the scalar (acoustic pressure) and vector (the acoustic particle velocity) effects are closely related. Only when the acoustic field is described by both the potential and kinetic energies, we may understand the mechanisms of propagation, diffraction and scattering of acoustic waves on obstacles, as a form of energy image. This attribute of intensity method can also validate the results of CFD/CAA numerical modeling which is very important in any industry acoustic investigations.
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Abstract

There is a considerable increase in the use of noise barriers in recent years. Noise barriers as a control noise solution can increase the insertion loss to protect receivers. This paper presents the results of an investigation about the acoustic efficiency of primitive root sequence diffuser (PRD) on an environmental single T-shape barrier design. A 2D boundary element method (BEM) is used to predict the insertion loss of the tested barriers. The results of rigid and with a different sequence diffuser coverage are also predicted for comparison. Employing PRD on the top surface of T-shape barrier has been found to improve the performance of barriers in comparison with the use of rigid and QRD coverage at the examined receiver locations. It has been found that decreasing the design frequency of PRD shifts the frequency effects towards lower frequencies, and therefore the overall A-weighted insertion loss is improved. It was also found that using wire mesh with reasonably efficient resistivity on the top surface of PRD improves the efficiency of the reactive barriers; however utilizing wire meshes with flow resistivity higher than the specific acoustic impedance of air on the PRD top of a diffuser barrier significantly reduces the performance of the barrier within the frequency bandwidth of the diffuser. The performance of a PRD covered T-shape barrier at 200 Hz was found to be higher than that of its equivalent QRD barriers in both the far field and in areas close to the ground. The amount of improvement compared made by PRD barrier compared with its equivalent rigid barrier at far field is about 2 to 3 dB, while this improvement relative to the barrier model "QR4" can reach up to 4-6 dB.
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Abstract

Pure-tone audiometry (PTA) and transient-evoked otoacoustic emissions (TEOAEs) were determined in 57 classical orchestral musicians along with a questionnaire inquiry using a modified Amsterdam Inventory for Auditory Disability and Handicap ((m)AIADH). Data on musicians' working experience and sound pressure levels produced by various groups of instruments were also collected. Measured hearing threshold levels (HTLs) were compared with the theoretical predictions calculated according to ISO 1999:1990. High frequency notched audiograms typical for noise-induced hearing loss were found in 28% of the subjects. PTA and TEOAE consistently showed a tendency toward better hearing in females vs. males, younger vs. older subjects, and lower- vs. higher-exposed to orchestral noise subjects. Audiometric HTLs were better than theoretical predictions in the frequency range of 2000-4000 Hz. The (m)AIADH scores indicated some hearing difficulties in relation to intelligibility in noisy environment in 26% of the players. Our results indicated a need to implement a hearing conservation program for this professional group.
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Abstract

n the paper, the simulation PROP5 program with the road model defined as a noise source and road surroundings model, is used to predict the efficiency of noise protecting means for the chosen building. The appropriate models of verified accuracy have been chosen by comparison of the simulation results with field measurements (Walerian et al., 2010). Here, using the pre-tested simulation program, the possibility of acoustic climate improvement has been analyzed in the ranges of practical variations of the input parameters. The road parameters: its geometry (number of lanes and their positions) and traffic structure over lanes (vehicle flow rates and their average speeds) have been taken under consideration as changeable parameters, that could be corrected to obtain acoustical climate improvement. Moreover, an acoustical screen designing has been considered. The screen efficiency has been evaluated under conditions defined by the input parameters of the road and its surroundings.
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Abstract

The sound speed and parameters of nonlinearity B/A, C/A in a fluid are expressed in terms of coefficients in the Taylor series expansion of an excess internal energy, in powers of excess pressure and density. That allows to conclude about features of the sound propagation in fluids, the internal energy of which is known as a function of pressure and density. The sound speed and parameters of nonlinearity in the mixture consisting of boiling water and its vapor under different temperatures, are evaluated as functions of mass concentration of the vapor. The relations analogous to that in the Riemann wave in an ideal gas are obtained in a fluid obeying an arbitrary equation of state. An example concerns the van der Waals gases. An excess pressure in the reflected wave, which appears when standard or nonlinear absorption in a fluid takes place, is evaluated in an arbitrary fluid.
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Abstract

Ultrasonic methods of human body internal structures imaging are being continuously enhanced. New algorithms are created to improve certain output parameters. A synthetic aperture method (SA) is an example which allows to display images at higher frame-rate than in case of conventional beam-forming method. Higher computational complexity is a limitation of SA method and it can prevent from obtaining a desired reconstruction time. This problem can be solved by neglecting a part of data. Obviously it implies a decrease of imaging quality, however a proper data reduction technique would minimize the image degradation. A proposed way of data reduction can be used with synthetic transmit aperture method (STA) and it bases on an assumption that a signal obtained from any pair of transducers is the same, no matter which transducer transmits and which receives. According to this postulate, nearly a half of the data can be ignored without image quality decrease. The presented results of simulations and measurements with use of wire and tissue phantom prove that the proposed data reduction technique reduces the amount of data to be processed by half, while maintaining resolution and allowing only a small decrease of SNR and contrast of resulting images.
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Abstract

The pathological states of biological tissue are often resulted in attenuation changes. Thus, information about attenuating properties of tissue is valuable for the physician and could be useful in ultrasonic diagnosis. We are currently developing a technique for parametric imaging of attenuation and we intend to apply it for in vivo characterization of tissue. The attenuation estimation method based on the echoes mean frequency changes due to tissue attenuation dispersion, is presented. The Doppler IQ technique was adopted to estimate the mean frequency directly from the raw RF data. The Singular Spectrum Analysis technique was used for the extraction of mean frequency trends. These trends were converted into attenuation distribution and finally the parametric images were computed. In order to reduce variation of attenuation estimates the spatial compounding method was applied. Operation and accuracy of attenuation extracting procedure was verified by calculating the attenuation coefficient distribution using the data from the tissue phantom (DFS, Denmark) with uniform echogenicity while attenuation coefficient underwent variation.
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Abstract

The development of digital signal processors and the increase in their computing capabilities bring opportunities to employ algorithms with multiple variable parameters in active noise control systems. Of particular interest are the algorithms based on artificial neural networks. This paper presents an active noise control algorithm based on a neural network and a nonlinear input-output system identification model. The purpose of the algorithm is an active noise control system with a nonlinear primary path. The algorithm uses the NARMAX system identification model. The neural network employed in the proposed algorithm is a multilayer perceptron. The error backpropagation rule with adaptive learning rate is employed to update the weight of the neural network. The performance of the proposed algorithm has been tested by numerical simulations. Results for narrow-band input signals and nonlinear primary path are presented below.
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Abstract

There are many industrial environments which are exposed to a high-level noise, sometimes much higher than the level of speech. Verbal communication is then practically unfeasible. In order to increase the speech intelligibility, appropriate speech enhancement algorithms can be used. It is impossible to filter off the noise completely from the acquired signal by using a conventional filter, because of two reasons. First, the speech and the noise frequency contents are overlapping. Second, the noise properties are subject to change. The adaptive realisation of the Wiener-based approach can be, however, applied. Two structures are possible. One is the line enhancer, where the predictive realisation of the Wiener approach is used. The benefit of using this structure it that it does not require additional apparatus. The second structure takes advantage of the high level of noise. Under such condition, placing another microphone, even close to the primary one, can provide a reference signal well correlated with the noise disturbing the speech and lacking the information about the speech. Then, the classical Wiener filter can be used, to produce an estimate of the noise based on the reference signal. That noise estimate can be then subtracted from the disturbed speech. Both algorithms are verified, based on the data obtained from the real industrial environment. For laboratory experiments the G. R. A. S. artificial head and two microphones, one at back side of an earplug and another at the mouth are used.
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Abstract

There are many industrial environments which are exposed to a high-level noise. It is necessary to protect people from the noise. Most of the time, the consumer requires a miniature version of a noise canceller to satisfy the internal working place requirements. Very important thing is to select the most appropriate personal hearing protection device, for example an earplug. It should guarantee high passive noise attenuation and allow for secondary sound generation in case of active control. In many cases the noise is nonstationary. For instance, some of the noisy devices are switched on and off, speed of some rotors or fans changes, etc. To avoid any severe transient acoustic effects due to potential convergence problems of adaptive systems, a fixed-parameter approach to control is appreciated. If the noise were stationary, it would be possible to design an optimal control filter minimising variance of the signal being the effect of the acoustic noise and the secondary sound interference. Because of noise nonstationarity for most applications, the idea of generalised disturbance defined by a frequency window of different types has been developed by the authors and announced in previous publications. The aim of this paper is to apply such an approach to different earplugs and verify its noise reduction properties. Simulation experiments are conducted based on real world measurements performed using the G. R. A. S. artificial head equipped with an artificial mechanical ear, and the noise recorded in a power plant.
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