bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrasonically induced vascular damage to the mouse intestine
Authors: Miller Douglas L. , Gies Richard A.
Published: July 2002

The mouse intestine represents a valuable model system for evaluating exposure indices and safety guidelines for medical ultrasound. After anesthetized hairless mice are exposed to ultrasound in a 37°C degassed water bath, three types of vascular damage may be observed in the intestines: hyperemia, which appears to be due to heating, hemorrhage into the lumen, which apparently results from cavitation activity, and petechiae in the wall of the intestine, which apparently may be caused either by heating or by gas body activation. Continuous-wave exposure tends to yield thermal effects, while lithotripter shock waves induce nonthermal hemorrhages. The petechiae are greatly enhanced when gas bodies from ultrasound contrast agents are introduced into the circulation. The thermal effects require temperature elevations in excess of about 5°C for several minutes and may be related to the thermal index. The nonthermal effects require pressure amplitudes in excess of about 1.23 MPa for petechiae and 2.4 MPa for hemorrhages with 10-μs pulses at 1 MHz and may be related to the mechanical index. However, the cavitational effects appear to depend more strongly on ultrasonic frequency from 0.4–2.4 MHz than is indicated by the mechanical index. [Work supported by NIH CA 42947.]
Emotions in the singing voice: Acoustic cues for joy, fear, anger, and sadness
Authors: Langeheinecke Esther J. , Schnitzler Hans-Ulrich , Hischer-Buhrmester Monika , Behne Klaus-Ernst
Published: July 2002

Singers can vocally express their emotional interpretation of a musical piece. The analysis of melodies performed by trained sopranos in four labeled affective states, revealed differences in time, amplitude, spectral, and frequency parameters. The tempo was 40% slower in samples expressing sadness, while other modifications of rhythm showed no emotion-specific patterns. Complex amplitude modulations within a tone were reduced to two parameters: the maximum amplitude and its position. In joy and anger, that maximum amplitude was higher and appeared earlier within a tone. Sound-pressure levels were significantly lower in fear and sadness. The energy distribution in the spectrum, which is reflecting timbre, did not show any differences in the lower harmonics, but the peak amplitude of the singer’s formant (clustering of third to fifth harmonic) was significantly higher in joy and anger. The extent of the vibrato, a characteristic feature for the voice of a trained singer, and the variations of the extent depended on the emotional expression. The linear average of the vibrato note’s undulating frequency as an approximation for the perceived pitch differed up to 5 to 10 Hz between emotions, with a tendency to lower frequencies in sadness.
Turbine exhaust noise radiated by stack walls and tops
Authors: Reinicke Walter F. L.
Published: July 2002

Rapid progress in noise abatement of plants enforced by the German environmental legislation caused the reduction of, among others, the stack noise due to ventilators and combustion machines of power plants whereas flow noise inside and traffic noise outside the stack remained unchanged. This paper refers to investigations supported by the German Umweltbundesamt in 1981 when power plants were equipped with flue gas desulfurization units. The goal was to calculate the sound transmission in steps: Reflection of sound power induced to the stack, attenuation in the series of wide tubes, directivity of radiation from the opening with hot gas flow, and influence of wind on directivity. This holds also for combustion turbines (CT) where the influence of gas temperature on the directivity index and of the coupling with wind is stronger. Measurements of this effect at real turbines, however, failed, and there are only a few results of sound attenuation in the stack tube of CT combined with HRSG at lower temperatures. Typical ratios of sound power radiated by the wall and the opening of stacks will be presented on the basis of measured and calculated transmission loss data of steel tube walls.
Sound field studies of truck tires
Authors: Saemann E.-U. , Hald J. , Schuhmacher A.
Published: July 2002

To understand the noise source mechanism of tire/road noise better than in the past, it is essential to look at the complete sound field of a tire. In the technique of spatial transformation of sound fields (STSF), the Helmholtz integral equation is combined with the acoustical near-field holography. Thus it is possible to analyze the noise source in great detail and to calculate the sound in the far field. A drawback of the acoustical holography is that only planar views of the sound field can be calculated. One method to overcome this limitation is to combine the measurement results of STSF with the inverse boundary element method. By modeling the surface of the tire with boundary elements, the velocities on each element can be identified. First results will be presented. Comparing the sound field of a standing tire excited by a shaker with the sound field of a tire on a drum, it is possible to extract the part of the sound field that is caused by the geometry on the tire only.
Moment method calculation of radiation from a cylindrical tube with an infinite flange
Authors: Amir Noam , Matzner Chaim , Shtrikman Samuel
Published: July 2002

This work addresses the calculation of acoustic radiation from a cylindrical tube with an infinite flange, using the moment method. Expressions for the acoustic variables are presented in three separate regions: inside the tube, outside the tube, and on the boundary between them. Examination of the velocity field on this boundary shows that a singularity is present at the corner where the tube and flange meet. A set of basis functions is then developed, which can model this singularity efficiently, resulting in a solution that converges very rapidly. This is demonstrated by a comparison to a solution of the same problem, using the normal modes of the tube as basis functions. The present results are compared with those for the radiation from an unflanged tube, as given in the classic paper by Lewin and Schwinger.
The energy velocity of attenuating guided ultrasonic waves in plates
Authors: Bernard Arnaud , Deschamps Marc , Lowe Mike
Published: July 2002

The understanding of the propagation characteristics of guided waves is fundamental to their exploitation in nondestructive evaluation (NDE) techniques. Long-range testing methods often rely on the detection of the arrival of a wave packet which is understood to travel at the group velocity of the wave mode, and which is easily calculated. However, although in practice the group velocity is a perfectly adequate measure of the energy velocity of the wave packet, it is strictly correct only when the wave mode is lossless. The paper will examine the nature of the energy propagation vectors within a plate and the energy velocity of Lamb waves. Both elastic plates with lossless modes and plates with attenuation will be considered, the latter leading to differences between the group velocity and the energy velocity. Experimental results will be presented as validation, using a plate with material damping under conditions where the difference between group velocity and energy velocity is significant.
Some dynamic properties of the nonhomogeneous thermoelastic prestressed media
Authors: Kalinchuk Valery V. , Belyankova Tatyana I. , Puzanoff Yury E. , Zaitseva Irina A.
Published: July 2002

The problem of steady-state harmonic oscillations is considered for a nonhomogeneous thermoelastic prestressed medium. The mechanical parameters of this medium are considered to be arbitrary, sufficiently smooth functions of one of the coordinates (depth). The oscillations are realized under the action of the load or the rigid stamp oscillated on the medium’s surface. Two models of a nonhomogeneous thermoelastic medium are investigated: a nonhomogeneous layer of finite thickness on the un-deformed foundation and a nonhomogeneous layer on the surface of the homogeneous half-space. This investigation is based on the numeric construction of the Green’s function of the medium and the analysis of this function’s properties. The different types of changing with the depth of the numerical parameters of the layer’s material have been considered. The maximal changing of the parameters is located near the upper or lower bound of the layer. [Work supported by RFFI.]
Minimum audible movement angle in vertical, horizontal, and oblique planes: Effects of velocity and frequency content
Authors: Grantham D. Wesley , Hornsby Benjamin W. Y.
Published: July 2002

Minimum audible movement angles (MAMAs) were measured employing a pseudo-virtual method of stimulus presentation. All stimuli were digitally recorded through KEMAR’s two ears while he was positioned in an anechoic chamber with moving loudspeakers presenting sounds in one of seven planes: frontal horizontal, lateral horizontal, median sagittal, lateral vertical, or one of three different oblique planes. These recorded binaural stimuli were subsequently played through insert earphones to subjects seated in a darkened sound-insulated room. Subjects had to say on each trial whether a single moving sound moved ‘‘left’’ or ‘‘right’’ (‘‘up’’ or ‘‘down;’’ ‘‘front’’ or ‘‘back’’). With velocity held constant during a run (from 0 to 180°/s), stimulus duration was varied adaptively to track the MAMA threshold. Stimuli were Gaussian noise bursts that were either wideband, 4-kHz low-passed, or 4-kHz high-passed. Results will be discussed in terms of human sensitivity at low and high frequencies to dynamic information provided primarily by (1) changing interaural difference cues (frontal horizontal plane); (2) changing spectral cues (median vertical plane); and (3) combinations of changing interaural and spectral cues. [Work supported by NIDCD.]
A comparison of power-based and admittance measures of the acoustic reflex threshold
Authors: Feeney M. Patrick , Smith Kristen L. , Keefe Douglas H.
Published: July 2002

Contralateral acoustic reflex thresholds obtained using a standard clinical admittance system with a 220-Hz probe tone were compared to those obtained using a frequency-domain-based system for calculating wideband middle ear acoustic impedance and energy reflectance (ZR) [D. H. Keefe et al., J. Acoust. Soc. Am. 91, 470–485 (1992)]. A white noise activator presented through an ER-3A insert phone was used to elicit the contralateral reflex in ten normal-hearing young subjects. The probe signal, a 40-ms wideband chirp, was presented through an ER-10C microphone system for the ZR measures. The microphone signal was then digitized and stored for data analysis. Measurements of reflex-induced changes in the power absorbed by the middle ear and in wideband admittance were then derived to estimate reflex thresholds. An analysis of variance revealed that the average reflex threshold was about 16 dB lower for the power-based and wideband admittance measures than for the clinical measure (p<0.001). However, the two ZR measures were not significantly different from each other. These results have implications for reducing the level of sound exposure during clinical acoustic reflex testing, and for obtaining reflex thresholds that may be beyond system limits for standard clinical systems. [Work supported by OURC.]
Temporal jitter disrupts speech intelligibility: Simulations of auditory aging
Authors: Pichora-Fuller M. Kathleen , Schneider Bruce A. , Pass Hollis
Published: July 2002

Declines in auditory temporal processing have been observed in aging adults and may partially account for their difficulty in understanding spoken language. To mimic age-related loss of synchrony, sentences were temporally jittered. Intact and jittered SPIN sentences were presented in background babble, and sentence–final word recognition was measured in young listeners with normal hearing. If x(t) is the input signal, the internal representation of the signal, y(t), is assumed to be a time-delayed version of the input with the time delay, d, varying over time as y(t)=x[t−d(t)]. The first factor contributing to the jitter is the range of delays that might occur over time, modeled as the rms value of a band-limited noise. The second factor is the rate at which delays change, modeled as the bandpass of a band-limited noise. Word recognition was unchanged when the second factor dominated the jitter (rms=0.05 ms, BW=500 Hz), reduced slightly (10%) when the first factor dominated (rms=0.25 ms, BW=100 Hz), and reduced greatly (50%) when both factors contributed to the jitter (rms=0.25 ms, BW=500 Hz). This work is a first attempt to simulate temporal aspects of auditory aging.
Rupture pressures of membranes in the ear
Authors: Kringlebotn Magne
Published: July 2002

The rupture pressure differences across the tympanic membrane, the round window membrane, and Reissner’s membrane, as well as the force and corresponding pressure at the stapes footplate that causes the annular ligament to rupture, have all been measured in cadaver ears from Norwegian cattle. Reported mean rupture pressures are 0.41 atm for the tympanic membrane, larger than 2 atm for the found window membrane, 0.048 atm for Reissner’s membrane, and 30 atm for the oval window annular ligament. The latter pressure corresponds to 0.68-kg force applied to the footplate, having a mean area of 2.25 square mm. The ruptures of the tympanic membrane in cattle appeared without exception as small tears in the pars flaccida, quite opposite to human ears where ruptures in this area are very rare. The weakness of the pars flaccida is probably the reason for a lower rupture pressure for the tympanic membrane in cattle than in man. The rupture pressure of the tympanic membrane has also been measured in a few ears from fox.
The impact of placement of noise sources on directional hearing aid benefit
Authors: Ricketts Todd
Published: July 2002

The impact of the number and position of noise sources on measured directional hearing aid benefit was investigated. Directional benefit was quantified as the difference between hearing-in-noise test (HINT) signal-to-noise ratios for omnidirectional and directional hearing aid conditions. Noise environments included a single noise source placed at 180-degree azimuth, and three different five source arrays. All noise sources were uncorrelated and simulated noise only in the rear hemisphere, or noise surrounding the listener. Binaurally fit subjects listened through three different commercial hearing aids with significantly different polar directivity patterns. Testing was completed in two different reverberant environments with average reverberation times of 642 and 1456 ms. The relative level of hearing aid benefit differed significantly depending on the specific noise array used. Results revealed that the pattern of directional benefit across the noise environments could generally be predicted from differences in the hearing aids average polar directivity patterns. The directional benefit across hearing aid types revealed a similar pattern in both reverberant environments, though less benefit was generally obtained in the more reverberant environment in agreement with previous investigations of directional hearing aids. These results suggest that some previous investigations of directional benefit may need reevaluation.
Vibration analysis of rotating Euler beam
Authors: Hsiao Kuo Mo
Published: July 2002

The objective of this paper is to derive an exact expression for linear vibration equations of a rotating Euler beam, and investigate the effect of Coriolis and centrifugal force on the natural frequency of the rotating beam. Consider a uniform Euler beam rigidly mounted on the periphery of a rigid hub, which rotates about the hub axis fixed in space at a constant angular speed. The deformational displacements of the beam are defined in a rotating rectangular Cartesian coordinate system which is rigidly tied to the hub. The vibration of the beam is measured from the position of the steady-state axial deformation, and only infinitesimal free vibration is considered. The equations of motion for the rotating Euler beam are derived by the d’Alembert principle and the virtual work principle. In order to capture all inertia effect and coupling between extensional and flexural deformation, the consistent linearization of the fully geometrically nonlinear beam theory is used in the derivation. A method based on the power series solution is proposed to solve the natural frequency. Numerical examples are studied for the natural frequency of rotating beams with different angular velocity and setting angle.
Statistical energy analysis of two spring-coupled oscillators
Authors: Finnveden Svante
Published: July 2002

The response of two spring-coupled oscillators is investigated to develop our understanding of the weak coupling assumption in the modal approach to statistical energy analysis (SEA). The oscillators have stochastic uncoupled resonance frequencies that are normal distributed. For this case, the SEA coupling power proportionality holds for the ensemble average response, even for single frequency excitation, provided that a suitable definition of modal energy is adopted. It is seen that strength of coupling, from an ensemble point of view, is defined by the nondimensional ‘‘interaction strength.’’ This quantity may, for multi-modal systems, be interpreted as the ratio of the SEA conductivety to the product of the modal overlaps in each element, in which case the strength of the coupling measure agrees with the one that previously was found to govern the ensemble-averaged energies in one-dimensional wave guide systems.
Elastic wave scattering on a rod-like inclusion
Authors: Lavrov Nikolai A.
Published: July 2002

Wave propagation in an infinite (or semi-infinite) elastic solid containing a thin curvilinear rod-like inclusion (or liquid-filled cavity) is under consideration. The materials of the inclusion and the medium are isotropic, homogeneous, and linearly elastic. They differ in mass density, Young’s modulus, and Poisson’s ratio. The transversal size of the inclusion is much smaller than the large linear size which is assumed to be comparable with the incident wavelength. Numerical implementation of the direct methods (FEM, BEM, FDM, and their combinations) is connected with the principal difficulty caused by the degeneration of the region (presence of a small geometrical parameter). To overcome this obstacle an asymptotic decomposition is carried out. The original problem is reduced to two problems of decreased dimension. The first one is governed by the integral equation over the rod axis and describes the spatial dynamic effects of the process. The second one is 2-D problem of elastostatics. It is governed by the system of integral equations over the cross section and describes the deformation of it. The deflection of the cylindrical inclusion and the stress concentration are calculated in the case of the normal incidence.
Wavelets for speech processing
Authors: Kadambe Shubha
Published: July 2002

This presentation is focused on the application of wavelets for speech. Wavelet analysis was recently introduced to the signal and image processing community. Since then it has been applied to various problems. Robustness is an issue in the case of speech-based systems. Wavelet analysis seems to be one answer for this problem. In this lecture, an overview of what are wavelets and why wavelets are used for speech processing is given. Wavelet-based speech applications such as phoneme recognition and low bit-rate speech compression are discussed. Experimental results are provided to demonstrate the usefulness of wavelet analysis for speech applications.
Data-driven speech analysis for ASR
Authors: Hermansky Hynek
Published: July 2002

A typical large vocabulary automatic speech recognition (ASR) system consists of three main components: (1) the feature extraction, (2) the pattern classification, and (3) the language modeling. Replacing hardwired prior knowledge in the pattern classification and language modeling modules by the knowledge derived from the data turned out to be one of most significant advances in ASR research in the past two decades. However, the speech analysis module so far resisted the recent data-oriented revolution and is typically built on textbook knowledge of speech production and perception. Since it is believed that speech was optimized by millenia of human evolution to fit properties of human speech perception, deriving the speech processing knowledge from speech data may make some sense. The work describes some attempts in this direction. The linear discriminant analysis is used to learn about structure of speech signal to derive optimized spectral basis functions and filters (replacing conventional cosines of the cepstral analysis and conventional delta filters for deriving dynamic features) in processing the time-frequency plane of the speech signal. [Work supported by the Department of Defense and by the National Science Foundation.]
Speech visualization with auditory contours
Authors: Daniel Peter , Mundt Harald , Vormann Matthias
Published: July 2002

Speech perception is based on several steps of abstraction or contourization. In analogy to primary visual spatial contours Terhardt introduced the spectral pitch as the primary auditory spatial contour for further complex perceptions like phonemes, syllables, and sentences. Spectral pitch can be derived from the part-tone time-pattern (PTTP) as proposed by Heinbach [Acustica 67, 242–256 (1988)]. The PTTP can be seen as a physical equivalent of the spectral pitch contour. It consists of spectral maxima extracted from a spectrum analysis with time and frequency resolution according to the human ear. By resynthesis it can be shown that the PTTP contains all relevant information of the original signal. In addition one can edit and modify the PTTP of speech in a controlled way and auralize the changes through resynthesis. Further applications like the analysis of F0 contours, separation into voiced and unvoiced parts, virtual pitch analysis and segregation of simultaneous signals will be discussed.
Integration of three-dimensional and pressure sensitive palatography for speech production study
Authors: Wakumoto Masahiko , Masaki Shinobu , Honda Kiyoshi , Kusakawa Naoki , Ohue Toshikazu
Published: July 2002

Tongue-palate contact patterns during speech production have been measured by electropalatography (EPG). A conventional EPG system produces only a flat contact pattern, and does not provide data for either the three-dimensional aspect nor tightness of tongue-palate contact. This paper describes work integrating two recently developed palatography techniques, i.e., three-dimensional electropalatography (3D-EPG) [M. Wakumoto and S. Masaki, J. Acoust. Soc. Am. 102, 3166(A) (1997)], and pressure sensitive palatography (PSPG) [M. Wakumoto et al., Proceedings of ICSLP98]. The former displays the electrode pattern on a realistic palatal shape, and the latter measures contact pressure by a thin sheet sensor array. The two systems are combined using the following procedures: (1) individual palatal shape and contact patterns in the 3D field during consonant production are acquired by 3D-EPG, (2) dynamic tongue-palatal contact pressure during the same consonant production at the same contact area is monitored by PSPG. A preliminary experiment revealed contact pressure differences between voiceless and voiced consonants ([t] > [d]) while the contact area for these consonants were almost identical. This result suggests that the combined method can usefully augment the study of tongue-palate contact during consonant closures.
Cognitive theories of musical meaning
Authors: Kendall Roger A. , Carterette Edward C.
Published: July 2002

In this age of computer-based multimedia, it is useful to have a theoretical basis for combining audio and visual elements. Leonard Meyer (1956) discussed three primary types of musical meaning: referentialism, the arbitrary association of a musical event with a meaning outside of the music itself; formalism, the meanings in music arising from explicit knowledge about the formal structure of music; expressionism, meanings that arise from the tensions and releases embodied within the music itself. A similar model is suggested by Charles Peirce: index, parallel to Meyer’s ‘‘referentialism;’’ icon, in which musical patterns suggest connections to nonmusical frames of reference; symbol, similar to Meyer’s ‘‘expressionism.’’ It is clear that for either iconic or indexical meaning to be communicated, one must first apprehend the syntactical, ‘‘embodied meaning.’’ Therefore, the tripartite taxonomical categories outlined above are not discrete and orthogonal. It is best to conceive of musical meaning as existing along a continuum from areferential (syntactical) to referential. Since the visual frame of reference can also be mapped onto this continuum, a useful model for the interaction of audio and visual elements in film, dance, and animation arises. Audio-visual examples will illustrate the dynamic unfolding of meanings suggested by the model.
A novel computing structure for 3-D audio rendering with multiple sources
Authors: Chen Jiashu
Published: July 2002

A novel computing structure has been implemented for efficient 3-D audio production. Head-related transfer function (HRTF) on a sphere is represented as a linearly weighted combination of M eigenfunctions (EFs). Each EF is a function of frequency (or time) and each weight (of M) is a function of azimuth and evaluation. With this representation the 3-D positioned binaural signals of any single sound source can be obtained by first multiplying the dry signal with M weights and then convolving them with M EFs. Proper delay corresponding to ITD is introduced into binaural signals for the listener. Similarly, multiple sound source 3-D positioning is achieved by weighting each source with its corresponding weights and by filtering them with the same set of EFs. For every source added only one more set of weight has to be used to multiply the source without increasing the time-consuming EF filtering. It results in an order of magnitude or more MIPS saving compared with direct convolution, especially when the number of sources is large. This computing structure also offers scalability, graceful degradation, and other additional advantages.
Sound-propagation modeling with the enhanced ray theory in four dimensions
Authors: Maltsev Nikolay E.
Published: July 2002

Sound-propagation models, based on the ray theory, have existed for decades. Conceptional flaws in the standard ray theory, such as singularities on caustics and nonlinear boundary value problem for the rays, connecting source, and receiver, limit the scope of ray theory applications. In a recent report [N. E. Maltsev, Proc. of 16 ICA and 135 ASA Mtg. 3, 1935–1936 (1998)], the new approach, or enhanced ray theory (ERT), was presented, free from the defects of the standard ray theory, mentioned above. The 4D (three space dimensions plus time) ERT code was developed for the desktop computer. ERT code uses triangulation of the 3D environment by simplexes, for the approximation of the refraction coefficients of the liquid and solid parts of the media, parametrization of rays and wave fronts in barycentric coordinates, inside these simplexes, differential equations for eigenrays, and differential equations for wave fronts. Examples of ERT model predictions in the 3D environment for single-frequency and impulse sources, and comparisons with SAFARI code for benchmark problems are presented.
Statistics-governed channel simulation
Authors: Green Dale , Rice Joseph
Published: July 2002

A numerical channel simulator suitable for real-time, laboratory testing of undersea acoustic communication systems and governed by specified statistics for signal dispersion, coherence, and noise is presented. This work is motivated by a desire to understand the important parameters of nonstationary underwater acoustic channels and to explore the corresponding quality of service achievable within the constraints of those channel parameters. The simulator implements temporal variation (i.e., time coherence of both signals and interference) in either of two essentially equivalent ways: either as a Markov process, according to user-specified decorrelation time, or as realizations of spectral spreading. The quadrature response and underlying channel characteristics obtained from a physics-based model initiate and statistically govern the simulator. An important extension to the initializing statistics is inclusion of spectral spreading for individual macropaths, rather than the relatively gross spectral spreading formerly employed. Last, the simulator superposes recorded or simulated nonwhite, nonstationary channel noise, including co-channel network MAI (multiple-access interference) and jammers. Note that the interface between the physics-based model and the statistics-based real-time simulator is natural and well-defined. Thus any appropriate physics-based model or measured ocean channel statistics may be used to initialize the real-time simulator. [Work supported by ONR 32, the SSC-SD Independent Research Program, and the Navy SBIR Program.]
Influence of time variance on room impulse response measurement
Authors: Satoh Fumiaki , Hidaka Yoshito , Tachibana Hideki
Published: July 2002

The measurement of room impulse response is made under the assumption that the sound propagation system is time invariant. Actually, however, the air in a room is usually moving and the temperature is changing to a greater or lesser extent. In order to examine the influence of such time variance on the measurement of room impulse response, experimental investigations were performed in a reverberation room in which the air was excited by fans and in a concert hall in which the air-conditioning system was operated. Impulse response measurements were performed by the maximum-length sequence (MLS) method and the sweep pulse (SP) method and these results were compared. From the results, it has been found that the reverberation decay tends to become steeper by repeating the impulse response measurement to get high signal-to-noise ratio and the SP method is more robust than the MLS method against the influence of time variance of the atmospheric condition in a room.
Time variances with MLS technique: Theoretical considerations concerning rotating microphones in building acoustics
Authors: Weise Wieland , Schmitz Alfred
Published: July 2002

For some time now, the technique of maximum length sequence (MLS) measurement has been successfully applied in building acoustics. Rotating microphones which are otherwise useful, especially for the determination of sound reduction, cannot be used here because the time invariance of the system would be violated. The measurement errors arising when rotating microphones are used in experiments were already investigated previously. However, in view of the future process of standardization of measuring techniques in building acoustics, theoretical understanding is necessary. Theoretical analyses are presented which exhibit the deviations of the measurements. Emphasis is placed on the differences arising when a synchronous or asynchronous relation between microphone round trip time and MLS period is chosen.
Annoyance of the induction machine noise radiation
Authors: Öztürk Cüneyt , Bahadýr Aydýn
Published: July 2002

Designing and developing products to enhance the favorable and diminish the undesirable features of their sounds are the prime concerns of noise control engineers. Development of new products that might be based on the understanding of the physics of sound, how sound is perceived by the listeners, and how special features of sound determine our reactions are all significant issues of noise engineering. Noise problems of the induction machines mostly arise during the early stages of design and development. The main energy source in an electric motor is the magnetic field. Maxwell stresses act on the inner stator surface bore, giving rise to spectral distribution over the stator as a function of time. These forces excite the stator’s lamination and housing, which have distributed mass and damping. This study describes the noise radiation characteristics of the induction machine with special emphasis on the annoyance issue that varies behind the declared emission values and gains increasing significance with customer consciousness and competition in the market.
Noise problems of the induction motors
Authors: Öztürk Cüneyt
Published: July 2002

The audible noise produced by electrical machines is developed depending on the various energy sources that generally appear during the rotation of the rotor. Usually the main energy source in the electrical machines is the magnetic field. Maxwell stresses act on the stator core, armature, and stator laminations, and generally exhibit spectral distribution as a function of time. These forces may provide excitation on the mechanical resonances of the machine’s mechanical system that have a distributed mass, stiffness, and damping. The force waves and their possible contribution to overall machine noise can be predicted by analysis of the electrical design, which can be optimized to reduce their effect. Careful analysis and design are required, with perhaps additional magnetic core material to keep flux levels low, and air gap large, without compromising good performance. Behind the features of the magnetic and mechanical structure, the aerodynamic features and excitations provided by the air circulation and the movement can also gain significance when the similar interaction appears with the machine structure. Interaction might be amplified during the coincidence of the mechanical resonances and the provided excitation on similar frequencies.
Assessment of impact noise determined by binary traffic systems
Authors: Sattler Miguel A.
Published: July 2002

The environmental impact resulting from proposed solutions to solve problems related to the fast growth of Brazilian cities is rarely properly assessed. That is the case of urban traffic noise. There has been a significant growth of vehicles in the last years. In the face of the lack of resources by the public sector to provide adequate public transport for the population, traffic has been increasing considerably year after year. One of the alternatives attempted by the Secretary of Transport of the city of Porto Alegre, south of Brazil, to reduce traffic jams, is to implement an increasing number of binary traffic systems, by using two single-way roads instead of one two-way road. This has increased noise in previously quiet areas of the city. The present paper presents measured values of the resulting noise impact of such measures, considering noise levels before and after the introduction of one of these binary traffic systems.
The effect of road features on the traffic noise—Prediction and measurement
Authors: Foken Wolfgang
Published: July 2002

In order to calculate the noise level from road traffic, prediction methods are used in most countries, for instance the ‘‘RLS90’’ (‘‘Guideline for Noise Control at Roads’’) is the relevant calculating method in Germany. The initial situation is always the amount of cars, the percentage of trucks, and their velocities. In addition, features of the road are required, for example, the road pavement, the gradient, and the existence of traffic lights. They are considered to be surcharges. The aim of this paper is the critical evaluation of these road features and the comparison with measured data. The paper shows that traffic lights generally do not cause an increase of the noise level. It was noted that the surcharge for traffic lights depends on the traffic density and the percentage of trucks. Therefore, a general usage of the ‘‘RLS90’’ surcharge for traffic lights is questionable. The German ‘‘RLS90’’ often underestimates the effect of the road pavement. Measurements also indicate the necessity of defining the surcharge for the road pavement as a continuous function of the velocity. The surcharge for the road gradient does not depend on the velocity but a reliance on the percentage of trucks is assumed.
The new noise policy of the European Union
Authors: ten Wolde Tjeert
Published: July 2002

In 1996 the European Commission published a so-called Green Paper in which proposals were done for a future EU policy on environmental noise. More than 450 institutions and individuals commented and on the basis of these the European Commission concluded that there is more than sufficient support for most of the proposals and started the process of the further development of the policy. Central elements in the policy are the harmonization of the noise indicators and the assessment methods in the European Union, the introduction of noise mapping and action plans for cities and member states, and information of the public and periodical EU action plans. Target setting will probably remain the responsibility of the Member States or local authorities. It is the aim that the coherence and quality of the EU policy on noise sources will improve. In 1998 working groups started with the development of indicators, dose-effect relationships, computation and measurement methods, mapping procedures, and guidelines for abatement plans. An overview of their tasks and their progress shall be presented. In parallel the development of a first Directive for environmental noise began. The progress with this process shall also be reported.
Harmonization of computational and measurement methods for noise exposure in the European Union
Authors: Gottlob Dieter P. A.
Published: July 2002

In the framework of the new European noise policy, the European Commission has created working groups to assist in the preparation of this policy. The members are appointed by the Commission on the recommendation of the member states, local authorities, and various organizations. Working group 3 (WG 3) is dealing with the harmonization of calculation and measurement procedures for noise assessment, mapping, planning, and noise abatement. Calculation methods shall be elaborated for road, rail, aircraft, outdoor machinery, and industry. They shall be suited for calculating the long-term noise exposure as well as single events, especially from air and rail traffic. Additionally, they shall be developed for a variety of geometrical and weather conditions which occur in the member states. At the Copenhagen Conference (September 1998), WG 3 started working and discussed the work program with experts from various countries. It was decided that emission data and transmission models should be separated. Emission measurement procedures should be provided, and the propagation models currently in use should be improved, especially in their physical representation. In the next months an action plan will be elaborated. In this paper the current state of the discussions will be presented.
A new EU directive concerning the noise emission by equipment used outdoors
Authors: Irmer Volker K. P.
Published: July 2002

The Green Paper ‘‘Future Noise Policy’’ [COM(96) 540 final] identifies noise in the environment as one of the main environmental problems in Europe. It emphasizes the continuing need for legislative measures at the Community level concerning noise emission from various sources. In February 1998, the Commission adopted a proposal for a European Parliament and Council Directive on the approximation of the laws of the member states relating to the noise emission by equipment used outdoors [COM(1998) 46 final, published in OJ No. C 124, 22.04.1998, p. 1]. It intends to simplify legislation, to contribute to the smooth functioning of the internal market, and to protect the health and well-being of citizens by reducing the overall noise exposure. The proposal covers 55 types of equipment, all of which are to be marked with the guaranteed noise-emission level; in addition, noise limits are laid down for 19 types of equipment (13 already covered by existing directives, 6 new ones). Noise limits are laid down in two stages (the first one eliminating most noisy equipment, the second one taking into account advanced technology). The requirements of the proposal are explained and the progress made in the Council and European Parliament is reported.
Radio acoustic sounding of the planetary boundary layer
Authors: Peters Gerhard
Published: July 2002

Refractive index variations of the atmosphere caused by sound waves are used as tracers for radar waves in order to determine the sound velocity and thus the (virtual) temperature remotely. This combined usage of acoustic and electromagnetic waves—called ‘‘radio acoustic sounding system (RASS)’’—has gained considerable interest, as sensitive radar wind profilers have been used for one decade in atmospheric research and monitoring. The RASS function can easily be added to radar wind profilers with the help of sound sources at the radar site. Due to the sound attenuation, the range of most systems is limited to the typical depth of the planetary boundary layer, which is particularly important for the exchange of mass, energy, and momentum between atmosphere and surface. Due to refinements of the signal analysis, a measurement accuracy comparable to conventional in situ sensors has recently been achieved. In contrast to in situ measurements, RASS has the great advantage to provide continous and simultaneous data from many altitudes. RASS cannot only deliver accurate temperature profiles but also profiles of the mean wind and of high-frequency fluctuations of the vertical wind component. Currently a RASS-based method is being developed for high-resolution horizontal wind measurements.
Sonolysis of nitrophenol and nitrophenyl acetate in aqueous solution
Authors: von Sonntag C. , Tauber A. , Schuchmann H.-P.
Published: July 2002

The dual aspects of aqueous sonochemistry can be nicely demonstrated by the use of nitrophenol as a substrate. The nature and sonolytic yield of the products depends drastically on the state of dissociation of this substrate (pKa 7.1). At pH 4, the undissociated compound, being hydrophobic, is enriched in the boundary layer of the cavitational bubble and develops a partial pressure within the bubble, in contrast to the situation at pH 10 where the phenolate anion exists. Accordingly, at pH 4 the degradation is gas-phase pyrolytic, but at pH 10 it occurs in the aqueous phase induced by OH radicals. There has been a debate as to whether thermohydrolysis of substrates such as 4-nitrophenyl acetate, which has been thought to proceed in a layer of ‘‘supercritical’’ water surrounding the collapsing cavitational bubble, plays a role in their aqueous-solution sonolysis. New results, especially the absence of nitrophenol formation, indicate that this is not the case. This, as well as the formation of considerable amounts of OH-radical-induced and ‘‘deep pyrolysis’’ products clearly shows that the 4-nitrophenyl acetate system is incapable of specifically probing any domain of supercriticality.
Ultrasonic generator with frequency modulation used in sonochemistry
Authors: Sarbu Mircea Alexandru , Demeter Elek , Vinatoru Mircea , Constantinescu Adrian Daniel
Published: July 2002

The electronic generator includes an oscillator and a power stage working in tandem. It is supplied with an unfiltered rectified tension voltage. The signal applied to the transducer is completely modulated in amplitude, having a modulation sinusoidal frequency of 100 Hz. The adaptation transfer of power is realized by a voltage transformer, in this case the rate of voltages being 3.2. The input power was halved by a separate connection, at which one gets 0.707 of the maximum tension voltage. The output signal of the oscillator is frequency modulated with a white noise signal, the resulting signal having a frequency deviation less than 10% of the oscillation frequency. Frequency modulation by a white noise signal generates a broadband signal, very useful for the improvement of the efficiency of the chemical reaction. The carried experiments proved that the use of half of the transmitted power led to interesting results, too. So, for the case of the Weissler reaction of potassium iodine decomposition, at the same time of sonification there was practically a double concentration of the obtained substance, iodine, for the case of half of the power generator.
Effect of crosslinking on dynamic mechanical properties of polyurethanes
Authors: Fedderly Jeffry J. , Lee Gilbert F. , Lee John D.
Published: July 2002

The dynamic mechanical properties of five polyurethane compositions of varying crosslink density were measured using a resonance technique. The five crosslinked polyurethanes are the reaction products of 4,4′-diphenylmethane diisocyanate and various polypropylene glycol diol/triol blends. Crosslink density was controlled by varying the ratio of diol to triol. The dynamic mechanical data was fit to the Havriliak-Negami dispersion relation. The most significant effect of increased crosslinking was to increase the low-frequency modulus. A slight increase in relaxation time was observed as crosslink density was increased over the given range, which approximately correlates with the modest change in glass transition temperature seen in this series. Values for the high-frequency modulus and asymmetry of the dispersion were not effected by crosslink density. Comparisons are also made with the sound absorption height and width limits predicted for uncrosslinked polymers [Hartmann et al., J. Acoust. Soc. Am. 101, 2008–2011 (1997)]. [Work supported by the Carderock Division of the Naval Surface Warfare Center’s In-house Laboratory Independent Research Program sponsored by the Office of Naval Research.]
Measurement of ground impedance—Test of method
Authors: Jonasson Hans G. , Oegren Mikael
Published: July 2002

Within the frame of a Nordtest project, a method to measure the acoustic impedance of ground has been tested. The Nordtest method has been tested by four different measurement teams, each carrying out four measurements on each of four different test sites. The results show good agreement between the different measurement teams. The measurement uncertainty is less than or equal to one ground class. The proposed Nordtest method, which has much in common with a similar standard under preparation by ANSI, is based on the following: A loudspeaker generating pink noise is used. The measurements are carried out in octave bands. The ground is divided into 12 different classes. For each class the level difference has been calculated theoretically using a specified ground impedance model based on the flow resistivity. The class assigned to a certain ground surface is the one yielding the smallest difference between measured and calculated data. The result reported is the ground class. Different indicators are used to assess the quality of the measurement.
Acoustic signal attenuation, velocity, and filtering by beach sand, with different water content
Authors: Tavossi Hasson M. , Tittmann Bernhard R.
Published: July 2002

The high-intensity acoustic pulses, transmitted by a piezoelectric transducer of center frequency 40 kHz, are sent through a beach sand medium and received, at up to 35-cm depth, by an identical receiver transducer. The received acoustic signals are then amplified and analyzed on computer. Experimental data are collected at different depth and water content of pore spaces between the grains. Experimental results show that sound arrival velocity decreases from 197 m/s for humid sand, to 120 m/s for partially water-saturated sand with air bubbles, which are always present. Acoustic signal attenuation increased by a factor of ten, from humid to partially water-saturated sand. The peak frequencies in FFT of the transmitted acoustic signal and its speed are dependent on compactness of the medium. The peak spectral amplitude is close to 9.7 kHz for humid sand and 7.5 kHz, for sand partially saturated with water. Experimental data on wave dispersion, phase velocity, and attenuation versus frequency, up to 24 kHz, are obtained. Latest results and tentative theoretical interpretation of experimental data, including porosity and grain size distribution, will be presented.