bluuebunny/crossref_metadata_2025 huggingface dataset:
In situ and experimental observations of the relationships between euphausiid orientation, vessel lights, and acoustical scattering
Authors: Benfield Mark C. , Ashton Michelle L. , Trevorrow Mark V. , Mackas David L.
Published: September 2013

During a collaborative investigation of zooplankton aggregations near a coastal fjord (Knight Inlet, British Columbia), surveys were conducted using down-looking echosounders and a digital imaging system (ZOOVIS). Two surveys conducted at night revealed that the presence or absence of external illumination on the vessel had a pronounced influence on measured acoustical scattering. The extremely short latency between shifts in illumination and changes in acoustical scattering suggested that differences in the orientations of scatterers were responsible for this phenomenon. High-resolution, in situ images of euphausiids (Euphausia pacifica) from ZOOVIS indicated that these organisms were present in a range of orientations ranging from horizontal to vertical, relative to the incident acoustical beam. Theoretical scattering models based on digitizations of in situ ZOOVIS images suggest that the magnitude of the observed changes in scattering, in response to altered illumination, may be accounted for by changes in euphausiid orientation. [Research supported by the ONR, Code 322BC.]
Behavioral observations of in situ copepods with a multibeam sonar
Authors: Jaffe Jules , Genin Amatzia , Ohevia Moti
Published: September 2013

In order to count and track copepods in three dimensions a multibeam sonar has been developed which operates at a frequency of 1.6 MHz. The sonar uses an analog version of a crossed array in order to localize animals in 2–4-liter volumes. The system uses an 8×8 beam configuration to localize animals at subcentimeter accuracy in range and centimeter accuracy across track. Sensitivity was measured in a test tank via the injection of animals, and it was found that the system was capable of measuring reflections of animals as small as 1–2 mm at ranges of at least 2 m. In order to measure the behavior of the animals under different environmental conditions in situ, experiments were conducted in the Gulf of Eilat. Here, the sonar was mounted on a tripod and aimed horizontally. Processed results yielded over 200000 individual tracks that lasted from 2 to 40 s. The results demonstrated that zooplankton retain their depth under up- and down-welling currents of 1–2 cm/s (as measured with injected fluorescein dye). This is unlike their response in the horizontal, where the animals are passively swept with the currents.
Contribution of active and passive acoustics to study oceanographic processes feeding whales in a critical habitat of the St. Lawrence Estuary
Authors: Simard Yvan , Roy Nathalie , Simard Yvan , Cotté Cédric
Published: September 2013

The head of the main channel of the continent in eastern Canada is the site of particular oceanographic processes that are responsible for the creation of a persistent feeding ground regularly visited by baleen whales from the Atlantic for centuries. Multifrequency acoustics coupled with ADCP and hydrographic measurements has been used to map the krill and capelin aggregations in 3D and visualize their local concentration process under tidal forcing and upwelling at the channel head. The krill scattering layers, pumped into the area by the strong two–layer estuarine circulation, appear to be concentrated during flood by tidal currents forced against the slopes and upwelling, to which depth-keeping krill is reacting by swimming down. Capelin also tends to concentrate on slopes and neighboring shallows. This highly recurrent process generates rich patches that are contributing with the mean circulation to make this area the richest krill aggregation in Northwest Atlantic. This critical habitat is located in a major continental seaway. Passive acoustics techniques are explored to locate whale calls and map the use of this area in continuing months, especially by blue and fin whales, with the aim of understanding their movements to improve their protection.
Importance of pulse synchrony to stone comminution in dual-pulse lithotripsy
Authors: Pishchalnikov Yuri A. , McAteer James A. , Pishchalnikova Irina V. , VonDerHaar Richard J. , Williams James C. , Evan Andrew P. , Bailey Michael R. , Cleveland Robin O.
Published: September 2013

We have characterized the acoustic output and in vitro stone breakage of the first dual-pulse lithotripter approved for patient treatment. Direx Medical Systems provided their Duet lithotripter and two timing circuits—a standard circuit that fires both electrodes in synchrony and a modified circuit that allows pulse delay. We assessed the effect of synchronous and ∼10-μs delayed dual pulses on breakage of model stones. When synchrony was very close the waveform had a single peak ∼70 MPaP+, followed by a negative trough ∼12 MPa The waveform from one head was about half this amplitude. Pulses close in timing but not synchronous (∼1–2-μs apart) showed amplitude-summed conjoined peaks. Dual pulses fired ∼10 μs apart appeared as independent SWs. Simultaneous pulses broke stones better than pulses delivered by only one head (p<0.001) and better than ∼10-μs delayed pulses (p<0.0001). Delayed dual pulses were also less efficient than pulses delivered by one shock head (p<0.001). Pulse timing is critical to stone breakage in dual-pulse lithotripsy. When pulse timing is very close, breakage is better than pulses from one source. The observation that asynchronous pulses are less efficient highlights the importance of precision in dual-pulse SW sources. [Work supported by NIH-DK43881, ONRIFO-N00014-04-1-4010.]
Comparison between an open-cage electrode lithotripter and an encapsulated electrode lithotripter
Authors: Chitnis Parag V. , Cleveland Robin O.
Published: September 2013

We compare the acoustic and cavitation field of two electrohydraulic lithotripters: one employed an open-cage electrode (OCE) and the other an encapsulated electrode (ECE). Acoustic pressure was measured with a fiberoptic probe hydrophone and cavitation using a passive detector consisting of two confocal transducers. The focused shock waves (FSW) of the two lithotripters were similar in shape and at 20 kV, peak positive pressure (P+) for the OCE was 23.2±4.4 MPa and peak negative pressure (P−) was 9.0±1.5 MPa. For the ECE the peak pressures were 30.8±9.4 and −8.2±1.3 MPa, respectively. However, the direct waves (DW) were different. The OCE-DW was triangular shaped and almost entirely positive pressure, whereas the ECE-DW consisted of numerous cycles and had a peak negative pressure of 1.3 MPa. For both electrodes the passive cavitation measurements exhibited two acoustic emissions characteristic of inertial collapses. For the OCE the first emission was weak (in comparison to the second emission) and was attributed to scattering of the FSW. For the ECE both emissions were of similar amplitude, indicating that the DW generated cavitation bubbles that were forced to a violent collapse by the FSW. The ECE produces two violent cavitation events for every shock wave. [Work supported by HMT and NIH.]
Architectural-acoustics consulting
Authors: Hoover Anthony K.
Published: September 2013

Consulting involves both the science of acoustics and the art of communication, requiring an array of inherent and created skills. Perhaps because consulting on architectural acoustics is a relatively new field, there is a remarkable variety of career paths, all influenced by education, interest, and experience. Many consultants juggle dozens of chargeable projects at a time, not to mention proposals, seminars, teaching, articles, business concerns, and professional-society activities. This paper will discuss various aspects of career paths, projects, and clients as they relate to architectural-acoustics consulting. The intended emphasis will be considerations for those who may be interested in such a career, noting that consultants generally seem to thrive on the numerous challenges.
What happens when you want to talk to the animals: lessons of a career in animal bioacoustics
Authors: Bowles Ann E.
Published: September 2013

Animal bioacoustics (AB) is the study of sound in nonhuman animal biology. I entered the field because I was interested in the evolution of language, and I wanted to study the acoustic communication of whales and dolphins. Topics like this within the scope of AB make the discipline accessible to students and laypeople. Although career opportunities are limited (professionals declaring AB as their primary area represent only 3% of ASA membership [http://www.acoustics.org/WIA, statistics for 2000]), an interest in AB can foster entry into more marketable disciplines. It has been a particularly important avenue for bringing women into careers in traditionally male-dominated subject areas. For example, women represent 14% of the ASA membership and 12% or fewer of those declaring Underwater Acoustics, Engineering Acoustics, and Noise as their primary interest. However, 25% of those declaring AB as their primary interest are women, and AB includes all three topic areas within its scope. Unfortunately, AB is still fairly inaccessible to interested lay professionals such as educators, science writers, and environmental planners. By helping them to develop a deeper understanding of topics in AB, ASA can help them foster careers in acoustics.
Physical modeling of Tibetan bowls
Authors: Antunes Jose , Inacio Octavio
Published: September 2013

Tibetan bowls produce rich penetrating sounds, used in musical contexts and to induce a state of relaxation for meditation or therapy purposes. To understand the dynamics of these instruments under impact and rubbing excitation, we developed a simulation method based on the modal approach, following our previous papers on physical modeling of plucked/bowed strings and impacted/bowed bars. This technique is based on a compact representation of the system dynamics, in terms of the unconstrained bowl modes. Nonlinear contact/friction interaction forces, between the exciter (puja) and the bowl, are computed at each time step and projected on the bowl modal basis, followed by step integration of the modal equations. We explore the behavior of two different-sized bowls, for extensive ranges of excitation conditions (contact/friction parameters, normal force, and tangential puja velocity). Numerical results and experiments show that various self-excited motions may arise depending on the playing conditions and, mainly, on the contact/friction interaction parameters. Indeed, triggering of a given bowl modal frequency mainly depends on the puja material. Computed animations and experiments demonstrate that self-excited modes spin, following the puja motion. Accordingly, the sensed pressure field pulsates, with frequency controlled by the puja spinning velocity and the spatial pattern of the singing mode.
On the development of German beating-reed organ pipes during the 19th century
Authors: Braasch Jonas
Published: September 2013

In the 19th century organ literature, it is often claimed that German organ builders generally adapted the way of building their beating-reed pipes after being influenced by new developments from England and France. To investigate whether this hypothesis is true or false, the reed-pipe sounds of several German historic organs and an English organ by Henry Willis were measured and analyzed. The outcome of the analysis, however, cannot confirm the given hypothesis. Organ builders of the 18th century, such as Gottfried Silbermann for example, were already able to build beating-reed pipes similar in sound to the pipes that are used nowadays in Germany. It is noteworthy that Silbermann used closed shallots in some of his stops, although they are thought to be one of the main inventions in the English and French organ reforms. The use of higher wind pressures, which is also a main part of this reform, on the other hand, never became a common standard in Germany, as was the case for France and Great Britain.
Children’s quality of life in a noisy world
Authors: Schulte-Fortkamp Brigitte
Published: September 2013

On 30 April 2003 during the International Forum Noise Awareness Day European experts from the fields of medicine, acoustics, sociology, psychology, city planning, and traffic regulation led the current discussion on the risks of noise pollution for children at the Institute of Technical Acoustics at the Berlin Technical University, Germany. Studies probing into the negative effects of noise exposure upon the psychic, cognitive, and emotional functions of children are of a quite recent date. Even the quality of life of children as auto-directed experience and functionality is only now starting to get recognized; of special interest are the changes in self-awareness, performance, and health. The Forum focused upon methodological reflections for the collection of data as well as studies regarding the living conditions of children under sound exposure from different perspectives. In this context the research of sound effects has taken initial tentative steps to break away from the tried-and-true procedures of the last 30 years. Next to applied science, investigating fundamentals will need to be considered. Aiming at a networking process is one of the goals conducting the ‘‘Tag gegen Lrm—International Noise Awareness Day.’’
Hearing loss and tinnitus in adolescents and young adults
Authors: Holmes Alice
Published: September 2013

Little attention has been paid to hearing abilities and the effects of noise on the normal adolescent and young adult population. A series of studies will be presented on the prevalence of hearing loss and reported effects of hearing loss and tinnitus in adolescents and young adults from different cultural backgrounds. Adolescents and young adults from different backgrounds may tend to seek or avoid various noise environments that could be detrimental to their hearing and cause tinnitus. Attitudes and exposures to noise environments were evaluated to see if these may be correlated with their hearing losses and/or tinnitus. In addition, these adolescent and young adult subjects reported how often they used hearing protection in various noise environments. Finally, the issues of quality of life and the need for hearing conservation programs with these populations will be presented.
Regulations against the human nature
Authors: Elizondo-Garza Fernando J.
Published: September 2013

The discussion around the concept of the addiction to noise has evidenced the importance of noise for the human being and explains why in some cases the regulations fail to control the noise in cities. In this presentation the different uses, consciously or unconsciously, of the noise will be analyzed, uses that go from habits to maybe addictions. Also discussed are the implications of establishing regulations against the human nature as well as the importance of education to manage the noise and design acoustically instead of trying to ban the noise in some social circumstances.
Scattering of elastic waves in textured media
Authors: Yang Liyong , Turner Joseph A.
Published: September 2013

The investigation of wave propagation and scattering of elastic waves in heterogeneous, anisotropic media is of substantial interest to quantitative nondestructive evaluation and materials characterization. The scattering of elastic waves in polycrystalline media is primarily due to interaction with the grains. Knowledge of wave velocity and attenuation may be used to infer material texture in polycrystalline aggregates. In this presentation, a model for wave propagation and scattering in polycrystalline materials with texture is presented. Attenuations and wave velocities are discussed for a general orthorhombic material made up of cubic crystallites. The attenuations of each wave type are derived as a function of dimensionless frequency and wave propagation direction, respectively, for given orientation distribution coefficients (ODCs). The ODCs are, in essence, the coefficients of an expansion of crystallite of orientation distribution function (ODF) in terms of a series of generalized spherical harmonics. A relationship between the phase velocity and recrystallization variables, such as annealing time, is also investigated for specific examples. Finally, numerical results are presented and discussed in terms of the relevant dependent parameters. The results are anticipated to advance the field of materials characterization of statistically anisotropic media. [Work supported by DOE.]
Backscattering in the vicinity of a mode cutoff
Authors: Whitman Alan M. , Beran Mark J. , Frankenthal Shimshon
Published: September 2013

In a previous paper [Whitman et al., Waves Random Media 13, 269–286 (2003)] a set of coupled equations was derived that describes the intermodal scattering of acoustic radiation in a duct whose speed of sound varies randomly in space and time. In that paper the main interest was in modes that were not near cutoff. Here the solution of these equations in the vicinity of the cutoff is treated. It is found that near cutoff almost all of the energy is reflected back independently of the other duct parameters. In addition to presenting this result the mathematical structure of the equations in these regions is analyzed in order to elucidate the reason for the behavior. Some numerical results are also presented.
‘‘Watson, come here!’’
Authors: Humes Larry
Published: September 2013

This famous quote marked a unique historical event in the development of telephony and an early experiment involving hearing. Although our own Watson postdates that work (considerably!), the life and work of Charles S. Watson are true reflections of good science and significant growth in our knowledge of human hearing. On behalf of those speaking at and attending this session in honor of Charles S. Watson, we ask this Watson to ‘‘come here!’’ (or, perhaps as a colleague suggested, to ‘‘come hear!’’). We ask that he do so to permit us to pay tribute to the many ways he has influenced the fields of psychoacoustics and speech communication, in general, and our careers, in particular. This introduction will provide a very brief overview of Chuck Watson, the person, as well as the scholar. By doing so, this overview will lay a foundation for understanding the impact of this man and his work. Subsequent speakers will build upon this foundation, with special focus on Chuck’s work in the area of the perception of complex sounds.
Molecular psychophysics and sound-source identification
Authors: A. Lutfi Robert
Published: September 2013

Threshold and d-prime measures of performance are ubiquitous in psychophysics. Yet, because these measures require averaging over many responses they can conceal important aspects of the subject’s decision process as it is reflected in the data from trial to trial. Chuck Watson clearly demonstrated this some 4 decades ago in his Ph.D. thesis. He was an early advocate of a ‘‘molecular’’ approach to psychophysics that attends specifically to the relation between individual stimuli and their associated response on each trial. In recent years, a variant of the molecular approach, perturbation analysis, has been applied with great success to the problem of image identification in vision [J. Vision 2(1) (2002), special issue]. This talk reviews the application of this method to a similar longstanding problem in auditory psychophysics—the identification of sound sources. Published and previously unreported studies are presented that use synthesized sounds to investigate listener identification of the material, geometric, and driven properties of simple resonant sources—stretched membranes, clamped bars, and suspended plates. These studies show that when listeners are confronted with a complex identification task, for which there are multiple sources of acoustic information, they regularly adopt different decision strategies that yield the same level of identification accuracy (same d-prime). [Work supported by NIDCD.]
Neural mechanisms for spectral segregation
Authors: Sinex Donal G.
Published: September 2013

Humans exhibit a remarkable ability to segregate sounds produced by multiple sources that overlap in frequency and in time. It is likely that other species that use hearing also have this ability. To investigate the neural mechanisms that contribute to spectral segregation, responses of auditory nerve fibers (ANFs) and inferior colliculus (IC) neurons to harmonic complex tones and to the same tones with a mistuned component were measured. Mistuning leads to the perception of a new sound source and also produces dramatic qualitative changes in the temporal discharge patterns of IC neurons. In contrast, the same stimulus manipulation produces only modest quantitative changes in the responses of ANFs. These results indicate that the processing of complex tones undergoes a major transformation in the lower brainstem that is likely to contribute to perceptual segregation based on harmonicity. A computational model has been developed to investigate integrative mechanisms that may underlie this transformation. The model reproduces the distinctive discharge patterns of IC neurons, and suggests that these patterns arise as a result of narrow-band envelope extraction, followed by broadband excitatory–inhibitory interactions. Specific predictions of the model have been confirmed in subsequent electrophysiological experiments, providing further support for this interpretation. [Work supported by NIDCD.]
Chuck Watson’s ‘‘differential psychoacoustics:’’ Individual differences in auditory abilities
Authors: Kidd Gary R.
Published: September 2013

Chuck Watson was among the first in the psychoacoustic community to seriously address the topic of individual differences. At a time when there was little concern with variation among ‘‘normal listeners’’ in psychoacoustic research, Watson began a research program to document the range of human auditory abilities. The primary goals were to determine the number of distinct abilities, to specify the nature of each ability, and to document the distribution of these abilities in the general population. Thanks to Watson’s talent for organizing and directing large-scale projects and his workmanlike approach to science, a large and valuable body of data on human individual differences has been collected. The research program began about 20 years ago with the study of basic auditory abilities, and it has expanded to include other modalities and cognitive/intellectual abilities in adults and children. A somewhat biased view of the importance of this work will be presented by one of Watson’s many colleagues in this endeavor. The talk will provide an overview of this ongoing research program as well as a brief review of some related research by other investigators. New findings from recent extensions of this work will also be discussed.
Noise analysis of a simplified Michelson interferometer vibrometer hydrophone
Authors: Estes Lee E. , Cray Benjamin A.
Published: September 2013

The use of a Michelson interferometer to sense acoustic vibrations imposed on a water/plate/air boundary is investigated. To focus on fundamentals, a simplified interferometer is considered rather than the usual heterodyne or dual track homodyne configurations. Based on analytical models, the sensitivity limits due to photoelectron shot noise, laser light amplitude and phase noise, atmospheric turbulence, thermal vibration, and amplifier noise are predicted. Techniques for mitigation of turbulence and laser noise will be discussed.
The influence of the piezoelectric actuators distribution on the plate acoustic radiation
Authors: Wiciak Jerzy W.
Published: September 2013

The analysis of sound radiation with steady-state vibration of a steel plate with the system of piezoceramic elements was performed.The system of piezoceramic actuators consists of four pairs PZT4 squared elements with dimensions 10×10×1 mm3. The actuators were located symmetrically on the plate and driven 180 deg out of phase with the same signal. It was assumed that rectangular plate is fixed along one edge. Other edges have the free boundary conditions case. The structural vibration analysis of a plate with a system of piezoelectric actuators was performed with FEM ANSYS@ code for the first three modes. The hybrid [Kozien and Wiciak, Quantum Mol. Acoust. 24, 98–110 (2003)] and fluid structure interactive methods were applied to estimate the sound pressure radiated by a vibrating system plate and actuators. Analysis of the SPL radiated by a vibrating plate with piezoceramic actuators into chosen points in the acoustic field gave similar results with two applied methods. The small differences in results were possibly an effect of the boundary assumptions. The best results in the reduction of sound radiated by plate were obtained for the first mode. [Work supported by SCfFR.]
Detecting and classifying adhesive flaws between bonded elastic plates
Authors: Leiderman Ricardo , Barbone Paul E.
Published: September 2013

Nondestructively evaluting the quality of an adhesive bond is challenging. The reason is that the only way to measure bond strength is by measuring the force required to break a bond, after which the bond is broken. Localized adhesion flaws that diminish bond strength, however, also tend to diminish bond stiffness. For example, pockets of elevated porosity, microcracking, or other damage in the adhesive layer will simultaneously lower local bond strength and local effective bond stiffness. So guided, we formulate and solve an inverse scattering problem to reconstruct the effective stiffness distribution of an adhesive layer in a layered elastic plate. Our formulation is based on the method of invariant imbedding, and applies to isotropic and anisotropic elastic layers. We present two solutions of the inverse problem: the Born approximation and the exact solution. Both solutions are unstable, as is the nature of inverse scattering problems, and require some regularization in the presence of noise. We present computed examples and discuss the role of regularization.
Blind deconvolution for non-stationary acoustical systems
Authors: Gramann Mark R. , Erling Josh G. , Roan Michael J.
Published: September 2013

Blind deconvolution is a signal-processing technique that has been shown to be highly effective for removing multipath propagation channel-induced corruption of a signal. These algorithms are usually implemented as adaptive filtering processes that learn finite impulse response inverse filters based on measurements of the corrupted signal. A major limitation of these techniques is that a stationary propagation environment is generally assumed. This assumption is not valid for many real-world applications, such as active or passive sonar operating in a shallow-water environment or for communications systems with moving sources or receivers. For slowly varying systems, standard algorithms with adaptive learning rates that improve convergence speed, such as frequency-domain implementations of the Infomax and Natural Gradient algorithms, may be sufficient. However, in systems where either the input signal or impulse response change rapidly, it becomes necessary to provide a means for tracking the statistical changes that occur in the input signal or impulse response. Approaches to tracking these changes through the use of a tracking algorithm such as Kalman filtering are discussed. [Work supported by Dr. David Drumheller, ONR Code 333, Grant No. N00014-00-G-0058.]
Wavefield stability in weakly range-dependent sound channels
Authors: Brown Michael G. , Beron-Vera Francisco J. , Rypina Irina , Udovydchenkov Ilya
Published: September 2013

It is shown that the mode-based ‘‘waveguide invariant’’ β is asymptotically equivalent to the ray-based ‘‘stability parameter’’ α. These parameters are known to control the dispersive properties of the sound channel and various measures of both ray path and travel time stability. This leads to the expectation that finite-frequency wavefield stability is also largely controlled by β (or α). PE simulations are shown to confirm this expectation. [Work supported by ONR.]
Three-dimensional wide-angle azimuthal PE solution to modified benchmark problems
Authors: Hsieh Li-Wen , Lin Ying-Tsong , Chen Chi-Fang
Published: September 2013

In predicting wave propagation, the size of the angle of propagation plays an important role; thus, the concept of wide angle is introduced. Most existing acoustic propagation prediction models do have the capability of treating the wide angle but the treatment, in practice, is vertical propagation angle. This is desirable for solving 2D (r–z) problems. Typically, 3D problems are dealt with an N by 2D approximation. To deal with problems possessing 3D effects, the azimuthal coupling terms have to be considered in PE approximation. Moreover, in extending the 2D treatment to 3D, the wide−angle capability is maintained in most 3D models, but it is still vertical. Hence, the concept of wide angle is introduced in the azimuthal direction to enhance the capability of predicting the azimuthal coupling and thus the 3D effects. A truncated wedge−shaped ocean which is modified from ASA benchmark problems is used in this study. The results show apparent 3D effects and validate the 3D wide−angle azimuthal PE model, a wide−angle version of FOR3D.
A variable rotated parabolic equation for elastic media
Authors: Outing Donald A. , Siegmann William L. , Collins Michael D.
Published: September 2013

There are several approaches for improving the accuracy of the parabolic equation method for problems involving sloping interfaces. Energy-conservation and single-scattering corrections have essentially resolved the acoustic problem, but these approaches have been less effective for problems involving elastic layers. Some promising results have recently been obtained using approaches based on mapped [J. Acoust. Soc. Am. 107, 1937–1942 (2000)] and rotated [J. Acoust. Soc. Am. 87, 1035–1037 (1990)] coordinates. The latter of these approaches provides greater accuracy for problems involving relatively steep interfaces. With the extension to variable slopes [J. Acoust. Soc. Am. 114, 2428–2429 (2003)], the rotated parabolic equation became a useful approach for solving a large class of range-dependent problems. This presentation will describe a generalization of the variable rotated parabolic equation to elastic media. At each change in slope, a new rotated coordinate system is introduced and the solution is interpolated onto the new grid. In the elastic case, this process requires special operators for changing variables, the rotation of the dependent variables, and a rotationally invariant quantity. Examples will be presented to illustrate and test the approach. [Work supported by the ONR.]
Investigation of early reflections on the perception of audio
Authors: Gorr John
Published: September 2013

The effects of early reflections in a nonsymmetrical control room were measured using time delay spectrometry and MLS methods. The tests revealed that comb-filtering patterns were the dominant source of spectral distortion. The mixing console reflections were investigated to reveal the subjective impact of the comb-filtering at the mix position. Tests were performed with and without acoustic foam on the console to determine the influence of the early reflections and then compared with theoretical values for the filtering patterns. Results were compared and used to qualify the subjective perception of the distortion.
Sound absorption and reflection from ceilings in open offices
Authors: Warnock Alf
Published: September 2013

Sound attenuation between work areas in open offices depends on barrier height and the sound-absorbing properties of the ceiling. Two methods for evaluating the sound-absorption ceilings are available: ASTM E1111, which gives a rating called the articulation class (AC), and ASTM C423, which gives sound-absorption average (SAA). Measurements of six ceiling systems made in accordance with ASTM E1111 and ASTM C423 provide a link between AC and SAA. Manufacturers often do not provide both ratings for their products, and it is useful to be able to use either rating system. SAA and measured AC for a 1.5-m-high screen are related by AC=102×SAA+91.4. SAA and calculated values of AC for a 1.8-m-high screen are related by AC=118 SAA+93. In the absence of E1111 test data, C423 SAA values can be used to select ceiling systems. The commonly recommended minimum SAA of 0.9 corresponds to an AC of 180 when the screen height is 1.5 m and to an AC of 200 when the screen height is 1.8 m. An approximate conversion from absorption coefficients to reflection coefficients agrees well with earlier work.
Use of surrogate samples to study variation of absorption coefficients of fiberglass with altitude
Authors: Godfrey Richard D.
Published: September 2013

ASTM C 423 identifies air temperature and relative humidity as significant parameters, but does not address air density effects. At constant temperature, air density decreases approximately 20% from sea level to 5000 ft altitude. In previous papers, normal and diffuse field analysis showed significant changes in predicted absorption coefficients with altitude. These predictions were validated experimentally for normal incidence by making measurements in a vacuum chamber. Reverberation chambers cannot withstand depressurization. They also exhibit significant interlaboratory measurement variability. Another method was soot. The Mechel design charts are normalized by two parameters. One is not dependent on air density. The other is the ratio of flow resistance and the impedance of air. If thickness is held constant, the effect of lowering air density can be studied by increasing the sample flow resistivity of the sample. This surrogate sample should emulate absorptive performance at high elevations in sea level laboratories. Impedance tube measurements using surrogate samples emulated the effects observed in the pressure chamber study. The next step is to use surrogate samples to investigate air density effects in diffuse fields using the ASTM C 423 test method in a single laboratory.
Twenty-five years with Van Holliday in the development of high-frequency technology and analysis algorithms to measure zooplankton distributions
Authors: Pieper Richard E.
Published: September 2013

Initial studies using high-frequency acoustics at four individual frequencies (0.5–3.0 MHz) were begun in the 1970s to measure acoustical scattering from zooplankton. Acoustical measurements were made at sea by profiling vertically in the water column. Zooplankton were collected, identified and measured, and target strength measurements were made on individual zooplankton in the laboratory. Concurrently, various acoustical scattering models were analyzed to enable the calculation of the size-frequency distribution of zooplankton from the acoustical data. A multi-frequency acoustic profiling system (MAPS) was then developed (21 different acoustical frequencies). This system was used to measure oceanic structure off of southern California, plumes off of central California, Gulf Stream features, and oceanic structure in the Irish Sea. Analyses of these data indicated that 21 frequencies were more than needed. Four to six frequencies were adequate for most studies, and the Tracor Acoustic Profiling System (TAPS) was developed. This system has been used and modified for a wide variety of studies. These studies range from large-scale patterns of zooplankton in the Arabian Sea to the measurement of thin layers in many different oceanic systems. The use of these systems now provides us with high-resolution measurements of zooplankton distributions in the sea.
Effect of orientation of euphausiids and copepods on acoustic target strength: Implications for measurements from down-looking and side-looking acoustic systems
Authors: Sutor Malinda , Cowles Timothy J.
Published: September 2013

Multifrequency acoustics is a potentially useful tool for zooplankton ecologists to rapidly map distributional patterns and determine taxonomic and size composition of scatterers. This is typically done with down-looking or side-looking acoustic systems. The ability to estimate taxonomic and size composition acoustically depends upon accurate models of scattering from zooplankton. In this study, distorted wave Born approximation (DWBA) models of individual zooplankton were used to illustrate that the frequency dependence of expected scattering is different for down-looking and side-looking acoustic systems due to the differences in orientation of scatters within the sampled volume. The results show that peaks and nulls occur at different frequencies for each system with maximum target strength differences of 30 dB. The models were used to predict volume scattering (SV) based on zooplankton collected from MOCNESS tows. Predicted SV was compared to SV measured by both a down-looking HTI acoustic system and a side-looking TAPS. The results showed that changes in orientation can have large effects on predicted total SV, particularly at higher frequencies, and demonstrate that choice of orientation parameters is important and different parameters should be used when comparing predicted SV with measured SV from down-looking or side-looking acoustic systems.
Comparing high-frequency scattering by a fish swimbladder and a gas-filled ellipsoid
Authors: Foote Kenneth G. , Francis David T. I.
Published: September 2013

High-frequency backscattering spectra have been computed for two air-filled sacs at 51-atm ambient pressure by means of the boundary-element method. One applies to the swimbladder of a 39-cm-long specimen of pollack (Pollachius pollachius), with known morphometry expressed in a 3181-node mesh. The other applies to a prolate ellipsoid, whose major axis is that of the mapped swimbladder, 14.1 cm, and whose minor axis, 1.24 cm, has been determined so that the volume of the ellipsoid is essentially identical to that of the mapped swimbladder. The dorsal-aspect backscattering cross section of each sac has been computed at each frequency over a normal distribution of tilt angles, measured relative to the longitudinal or major axis, with mean −4.4 deg and standard deviation 16 deg. Computations have been performed over the frequency range 20–40 kHz in increments of 25 Hz. The spectra are characterized and compared. [Work supported by ONR.]
Evaluation of the DORT method for the detection of microcalcifications in the breast
Authors: Robert Jean-Luc , Cohen-Bacrie Claude , Prada Claire , Fink Mathias
Published: September 2013

The DORT method (French acronym for diagonalization of the time reversal operator) is derived from the theory of iterative time reversal mirroring. It consists of a singular value decomposition of the time reversal operator obtained through single element transmissions and receptions. The number of eigenvalues relates to the number of bright point scatterers in the medium, and each eigenvector is the transmit signals that focuses on each bright scatterer. However, the signal-to-noise ratio (SNR) resulting from a single element transmit is low, which negatively impacts the sensitivity of the DORT method. This work consists of an adaptation of the DORT method to an imaging mode. Focused transmissions in the medium are used and a windowing preprocessing operation on the received signals significantly increases the sensitivity. The more robust behavior of this modified DORT method is tested on Field II simulated data and then on a phantom made of strings of different material embedded in speckle. Data on freshly excised breast surgical samples containing microcalcifications were processed and every microcalcifications was detected. Finally, results on in vivo acquisitions prove that the technique can accurately detect and locate microcalcifications in nonhomogeneous media with aberration.
A Galerkin discontinuous method for CAA: The reasons of a choice
Authors: Delorme Philippe , Peyret Christophe
Published: September 2013

As for many others disciplines, the numerical simulation is becoming a powerful tool for the study of the propagation of small disturbances in a heterogeneous flow (aero-acoustics). Some main applications are, on the one hand, aeronautics for the noise of the aircraft and, on the other hand, the propagation of the sound in the atmosphere. In general the development of a computer code goes by four phases: physical modeling, mathematic analysis, strategy of discretization, programming and validation. At each of these stages some specific choices are carried out. For physical modeling, it is necessary to choose a representative model. Then, it should be checked that the problem is well posed in existence and unicity. For the strategy of discretization the choice resides between the different methods and is guided by the geometries to study. Finally, the choice to use or not the possibility of strongly paralleling influences programming of the code. In this paper the reasons are described which led us to use a method of discontinuous the Galerkin type for the CAA. This method is then presented as well as architecture of the code. Finally, all this is illustrated for examples of simulations.
Ultrasonic imaging in noisy environment
Authors: Lewis John , Kaiser Matt , Irwin James , Sanchez Jose
Published: September 2013

Often times fossils are found buried within rocks of similar composition to the fossil. Ultrasonic imaging is becoming a popular form of nondestructive testing. The presentation covers techniques for imaging a fossil through nondestructive testing in three dimensions without risking damage to the fossil by removing extraneous material. The lecture begins with an illustration of immersion testing that uses longitudinal transducers to construct images of objects buried within a noisy environment of similar composition. Preliminary results give the location and shape of an object buried under a homogeneous layer. The first step to attaining this goal is to merely locate an object buried in a noisy debris field. A single sensor is all that is required to locate an object; however, two sensors allow the object’s position to be triangulated. Techniques for using single and multiple sensors are investigated to improve the search and imaging algorithms. The lecture continues with an in-depth discussion of the MATLAB signal-processing algorithms, which are required to generate a visual representation of the object. With some modification this technique also promises to be useful for security screening and landmine detection.
Physiology, anatomy, and plasticity of the cerebral cortex in relation to musical instrument performance
Authors: Tramo Mark Jude
Published: September 2013

The acquisition and maintenance of fine-motor skills underlying musical instrument performance rely on the development, integration, and plasticity of neural systems localized within specific subregions of the cerebral cortex. Cortical representations of a motor sequence, such as a sequence of finger movements along the keys of a saxophone, take shape before the figure sequence occurs. The temporal pattern and spatial coordinates are computed by networks of neurons before and during the movements. When a finger sequence is practiced over and over, performance gets faster and more accurate, probably because cortical neurons generating the sequence increase in spatial extent, their electrical discharges become more synchronous, or both. By combining experimental methods such as single- and multi-neuron recordings, focal stimulation, microanatomical tracers, gross morphometry, evoked potentials, and functional imaging in humans and nonhuman primates, neuroscientists are gaining insights into the cortical physiology, anatomy, and plasticity of musical instrument performance.
Noise and soundscape in Rome
Authors: Brambilla Giovanni
Published: September 2013

Noise pollution is an old problem in Rome. In 45 B.C. the Lex Julia Municipalis limited carriage traffic in the city center to specific times. Road traffic constitutes the most important and widespread noise source, and several investigations have been conducted since 1972, some aimed at developing a numerical model for predicting the hourly LAeq level. In order to reduce the large impact of this type of noise some measures have been carried out, including surfacing with porous asphalt, erection of noise barriers, limitation in time and spacing of private traffic, etc. However, most of the public complaints deal with noise from equipment operation and recreational activities rather than transportation systems. Moreover, the most famous tourist areas opened to pedestrians only are not as quiet as expected but their sound environment is usually rated more acceptable than noise from other sources at the same level. In compliance with the Italian legislation on noise, the Municipality of Rome issued a noise zoning code for its own territory, and a noise mapping is in progress, pursuant to the requirements of the 2002/49/EC European directive. A Geographical Information System has been also developed to manage all the aspects of noise pollution.
Noise in large cities in Brazil
Authors: Gerges Samir N. Y.
Published: September 2013

Large cities’ noise is considered by the World Health Organization to be the third most hazardous pollution, preceded by air and water pollution. In urban centers, in general, and especially in developing countries such as Brazil, large populations are affected by excessive noise due mainly to traffic flow. The Brazilian Federal Government specifies noise limits, but each state can enforce its own set of noise limits, providing they are lower. The rapid economic growth, together with large migration of northern Brazilians to the developing southern urban areas in search of more lucrative jobs in construction and industrial sectors, resulted in a fast increase in activities such as vehicle and bus traffic, home construction, and development of all necessary infrastructures to support this growth. Urban noise in Brazil has been receiving the attention of national authorities only since 1990, when the Federal Government approved the first ‘‘Program of Community Silence,’’ based on ISO R 1996-1971. This paper highlights the noise situation in the five largest and most populated cities in Brazil: Sao Paulo, Rio de Janeiro, Belo Horizonte, Porto Alegre and Curitiba [Zannin et al., Appl. Acoust. 63, 351–358 (2002)].
Noise issues in Kanagawa Prefecture
Authors: Yokoshima Shigenori , Tamura Akihiro
Published: September 2013

In Kanagawa Prefecture, bordering Tokyo Metropolis and the third most densely populated prefecture in Japan, various noises have caused serious problems in terms of living environment preservation and human health protection. This paper describes present states of noise issues in Kanagawa. Road traffic noise, remaining one of serious pollution issues, was monitored at a total 217 sites along trunk roads in Kanagawa from fiscal year 2000 to 2002. The percentage of the sites that achieve environmental quality standards for road traffic noise was approximately 20%. Noise caused by Tokaido Shinkansen trains, of which the total daily number is 287, also has negative impacts on inhabitants along the railway. As a result of the noise measurement from fiscal year 1994 to 2002, about 80% of the measurement sites exceeded environmental quality standards for Shinkansen railway noise during the years. In the areas surrounding the Atsugi Base, noise generated by training flights damagingly affects inhabitants’ daily life. The number of complaints due to the noise was largest among noise issues. Moreover, neighborhood noises, noises emitted during the nighttime operation of bars, restaurants and shops, and noises produced by work in out-of-door yards have recently provoked social issues.