bluuebunny/crossref_metadata_2025 huggingface dataset:
Robust shear wave motion tracking using ultrasound harmonic imaging
Authors: Song Pengfei , Zhao Heng , Urban Matthew W. , Manduca Armando , Pislaru Sorin V. , Kinnick Randall R. , Greenleaf James F. , Chen Shigao
Published: November 2013

Robust shear-wave motion detection is essential for producing reliable shear elasticity measurements for ultrasound shear-wave elastography (SWE). However, because shear-wave motion is extracted from radiofrequency signals which can be heavily contaminated by noise, shear-wave motion detection can be very challenging, especially for in vivo applications. This study investigated the implementation of harmonic imaging (HI) to facilitate more robust shear-wave tracking based on HI’s effectiveness in suppressing imaging noise associated with ultrasound reverberation, phase aberration, and clutter noise. A HI shear-wave tracking sequence was developed combining the pulse-inversion HI method with the plane wave imaging technique to transmit phase-inverted pulses at a high frame rate of several kilohertz. The backscattered ultrasound signals from phase-inverted pulses were added to suppress the fundamental and enhance the second harmonic component, from which the shear-wave motion was extracted. A pork belly phantom experiment showed that HI could significantly improve shear-wave motion detection by producing almost three-fold less underestimation of shear-wave motion and over ten-fold more precision for shear-wave speed measurements than fundamental imaging. An in vivo transthoracic case study of a human heart showed that HI substantially improved the success rate of shear-wave motion detection and could provide consistent estimates of the left ventricle myocardium stiffness.
Multipoint measurement of sound pressure and temperature in biological tissues by using optical fiber sensors
Authors: Kageyama Takashi , Koyama Daisuke , Akiyama Iwaki
Published: November 2013

Acoustic radiation force impulse (ARFI) has been actively studied in the field of medical ultrasonics. ARFI generates shear wave in the tissue to evaluate the tissue hardness using that velocity, and this method is applied to the diagnosis of liver tumor. Generally, long pulses are used for ARFI; therefore, we need to take account of thermal and physical effects on biological body. According to the regulation of Food and Drug Administration (FDA), the acoustic output of diagnostic ultrasound is approved as follows: Ispta.3 <720 mW/cm2, MI < 1.9. However, there are some reports that we have possibilities to affect body thermally and physically even under these conditions. In this report, we propose the optical fiber system using fiber Bragg grating (FBG) to measure ultrasound pressure and temperature change separately. The purpose is that we measure the temperature range of 4 degrees at the resolution of 0.1 degree and the sound pressure range of 10 MPa. We utilized an optical fiber which had 10 mm FBG in the center; moreover a narrowband light source and a photo detector to modulate reflected light signals by FBG to electrical signals. We obtained 3.2 μV/Pa and 9.5 pm/degree as the sensitivities of 10 mm FBG.
Concentration of blood components by acoustic radiation force
Authors: Kennedy Daniel , Sporbert Brianna , Gerhardson Tyler , Mealy Dane , Rust Michael , Lipkens Bart
Published: November 2013

We have recently reported on macro-scale separation of lipids from red blood cells (J. Acoust. Soc. Am. 133(5, Pt. 2), 3279). In this system, the acoustic radiation force is used to trap red blood cells and lipid particles in a standing wave. Subsequent clumping of red blood cells results in gravitational settling of the red blood cells. Similarly, coalescing of lipids results in rising of the lipids out of solution. We now report on more detailed measurements of the concentration and separation of various blood components, such as red blood cells, white blood cells, and platelets. Porcine blood was used in the experiments and diluted by a factor of ten in phosphate buffered saline. A VetScan HM5 hematology analyzer was used to do the blood count. Inlet flow rate through the device was 16 ml/min, the concentrate flow rate of the blood components was typically about 1 ml/min. The transducer was a 2 MHz PZT-8 operating at 10 W. No lysing was observed in any of the experiments. Results indicate successful capture of red blood cells and white blood cells with separation efficiencies in excess of 90% in a single pass. [Work supported by NSF PFI:BIC 1237723.]
Far-field approximation for a point-excited anisotropic plate
Authors: Magliula Elizabeth A. , McDaniel J. Gregory , Pierce Allan D.
Published: November 2013

An analytic approximation is derived for the far-field response of a generally anisotropic plate subject to a time-harmonic point force acting normal to the plate. This approximation quantifies the directivity of the flexural wave field that propagates away from the force, which is expected to be useful in the design and testing of anisotropic plates. Derivation of the approximation begins with a two-dimensional Fourier transform of the flexural equation of motion. Inversion to the spatial domain is accomplished by contour integration over the radial component of wave number followed by an application of the method of stationary phase to integration over the circumferential component of wave number. The resulting approximation resembles that of an isotropic plate but involves wave numbers, wave amplitudes, and phases that depend on propagation angle. Numerical results for a plate comprised of bonded layers of a graphite-epoxy material illustrate the accuracy of the method compared to a numerical simulation based on discrete Fourier analysis. Three configurations are analyzed in which the relative angles of the layers are varied. In all cases, the agreement is quite good when the distance between force and observation point is greater than a few wavelengths.
Optimal design of composite plates based on wave propagation characteristics
Authors: McDaniel J. Gregory , Magliula Elizabeth A.
Published: November 2013

The present work is concerned with the design of composite plates that are optimized with respect to their wave propagation characteristics. For example, one may wish to design a composite plate such that the attenuation of a dominant wave is maximized. The optimization proposed here considers a composite plate with a specified number of layers. The material properties and thicknesses of the layers are considered as optimization parameters and these parameters are typically constrained in some way. For each choice of the optimization parameters, complex wave numbers and their associated wave shapes are calculated by using the semi-analytical finite element method developed by others. This method uses a finite element discretization in the thickness coordinate and a propagating wave solution in the lateral coordinates, resulting in a quadratic eigenvalue problem for the complex-valued wave number of each wave that the plate supports. One then computes a scalar cost function based on the complex wave numbers and their associated wave shapes, and proceeds by adjusting the optimization parameters to minimize the cost function. This presentation will describe the computational aspects of the optimization approach and will illustrate its potential by example. [Work supported by ONR under grant N000141210428.]
Acoustic scattering from finite bilaminar composite cylindrical shells-three-dimensional solution
Authors: Hayek Sabih I. , Boisvert Jeffrey E.
Published: November 2013

The acoustic scattering from a finite bilaminar cylindrical shell is analyzed using the exact theory of three-dimensional elasticity. The two lamina are perfectly bonded having the same lateral dimension but have different radii and material properties. The finite shell is submerged in an infinite fluid medium terminated by two semi-infinite rigid cylindrical baffles. The shell has shear-diaphragm supports at the ends z = 0, L and is internally filled with an acoustic medium. It is insonified by an incident plane wave at an oblique incidence angle. The scattered acoustic farfield is evaluated for various incident wave wavenumbers, shell thicknesses, shell dimensions, radii, and material properties. A uniform steel shell in water was initially analyzed to study the influence of shell geometries on the scattered acoustic farfield. A second shell made up of an outer elastomer shell bonded to an inner steel shell was also analyzed to study the influence of elastomeric properties on acoustic scattering. [Work supported by NAVSEA Division Newport under ONR Summer Faculty Program.]
Community-based inquiry: An example involving wind turbine noise
Authors: Piacsek Andrew A. , Palmquist Bruce
Published: November 2013

Community-based inquiry (CBI) is an approach to providing an active and collaborative learning environment for students in a science classroom. Inquiry-based learning has been shown to improve critical thinking skills, as well as retention of new concepts [Quitadamo et al., Life Sci. Educ. 7, 327–337 (2008)]. For a typical CBI project, all students in a class work simultaneously on single problem that has significance to the local community. The problem is generally structured as an open-ended investigation that incorporates concepts covered in class. Specific components of the problem can be assigned to groups of students; collaboration among groups helps the class arrive at “big picture” conclusions. At Central Washington University, the introductory calculus-based physics course was recently revised to incorporate a CBI project involving the acoustics of local wind turbines. Wind speed and sound level measurements were taken by faculty at two different sites under different weather conditions. Each student group chose a subset of the data to analyze, collaborating via an Internet-based shared document platform. The design and implementation of this project, as well some assessment results, will be discussed.
Development of an online undergraduate course in acoustics at the Berklee College of Music
Authors: Reuter Eric L.
Published: November 2013

Between 125 and 150 students take an introductory course in acoustics each semester at the Berklee College of Music in Boston, MA. As the popularity of acoustics has grown (owing in part to a new minor in acoustics and electronics) limited classroom facilities have made it difficult to meet the demand for sections of the introductory class. Development is nearly complete on a fully online version of the course that will be offered beginning in 2014. This paper will examine the curriculum, development of media assets, and various hurdles in the development process.
Greetings from the West: The people of Veneklasen Associates
Authors: Christoff Jerry P. , LoVerde John J. , Ortega Joe
Published: November 2013

Western Electro-Acoustic Laboratory (WEAL) was founded in 1947 by Paul S. Veneklasen, FASA, for the manufacture of precision acoustical instruments utilizing the Western Electric 640AA Precision Condenser Microphone. When asked in 1951 to provide acoustical consulting services on a jet engine test cell, the architect insisted on dealing with an individual, not a laboratory, and Paul S. Veneklasen & Associates (PSVA) was born. Renamed Veneklasen Associates (VA) after Paul Veneklasen’s death in 1996, VA and WEAL have had the privilege of employing excellent associates over 65 years of business. Many within this group have contributed to the science of acoustics, in several cases founding firms to continue the practice of acoustical consulting. Others like the principal author, employed since 1956, have remained at VA continuing to contribute and mentor others in the science of acoustics. All of us have benefited from Paul Veneklasen’s approach to consulting projects, his use of corroborating measurements, reporting style and the quest for solutions to acoustical problems. In addition, the firm carries on Paul Veneklasen’s tradition of in-house acoustical research to advance the field. The Poster traces this history in terms of its current and former employees and their careers with PSVA and VA.
Acoustic lineage of the electroacoustic research laboratory at University of Massachusetts Dartmouth
Authors: Brown David A.
Published: November 2013

This poster summaries the academic and industrial lineage of the electroacoustics research laboratory at the ATMC-UMass focusing on the influence and training of mentor Boris Aronov, his use of the energy method for solving transducer problems, and a summary of some of the new generation of students and their research projects. Aronov adapted variational methods and generalized coordinates to solve transducer problems using an energy-balance approach in the 1950’s in Russia under the tutorage of Lev Gutin at the Morphyspribor (Marine Physics Research Center), the soviet navy’s main Sonar Research Institute located in Leningrad (now Saint Petersburg). Shortly after immigrating to the United States in 1998, Aronov teamed up with David Brown at UMass Dartmouth and BTech Acoustics LLC, building a fruitful partnership involving undergraduate and graduate students focusing on underwater electroacoustic transducer and electroacoustic subsystem problems—ranging from basic research, materials characterization, transducer and subsystem modeling, prototype development, calibration, and manufacturing.
Academic genealogy of Lawrence A. Crum
Authors: Crum Lawrence A.
Published: November 2013

Lawrence Crum received his Ph.D. in physics from Ohio University in 1967; his advisor was Prof. F. Burt Stumpf. He studied as a postdoc under Prof. F. V. Hunt at Harvard from 1967 to 1968, and held faculty positions in physics at the U.S. Naval Academy from 1968 to 1978, where he supervised Trident Scholars—selected undergraduates who were able to perform the equivalent of a MS thesis. From 1978 to 1992, he held positions in the Department of Physics at the University of Mississippi, where he supervised a number of graduate students toward advanced degrees. Since 1992, he has held positions in the Departments of Electrical Engineering and Bioengineering at the University of Washington, where he has continued to supervise students toward advanced degrees. This poster will attempt to document the many students who have studied under Dr. Crum’s tenure during his academic career.
The academic family tree of Ingo Titze
Authors: Story Brad , Hunter Eric , Scherer Ronald
Published: November 2013

Pursuing a deep interest in understanding the complexities of human sound production, particularly singing, Ingo Titze received his Ph.D. in Physics under the tutelage of Bill Strong at Brigham Young University in 1972. His dissertation on computational modeling of vocal fold vibration launched a career in research and teaching that has had a profound influence on the field of voice and speech science. Although his research alone is prodigious, Ingo Titze created an academic family that stretches far and wide. This presentation will trace the careers and research of the many students and scientists that were trained by Ingo Titze or influenced by his training.
Roots and branches of the acoustics program at Brigham Young University
Authors: Thomas Derek C. , Gee Kent L. , Neilsen Tracianne B. , Leishman Timothy W. , Sommerfeldt Scott D. , Blotter Jonathan D. , Thomson Scott L. , Strong William J.
Published: November 2013

Acoustics research at Brigham Young University has a rich history extending back over half a century. The tradition of acoustics continues to this day as BYU is home to one of the largest student chapters of the ASA. The academic roots of current and former faculty will be presented. The locations of the branches (students) will also be presented to illustrate the growth and development of the program and the impact on the broader acoustics community.
One descendant of David Blackstock of the University of Texas at Austin
Authors: Lipkens Bart
Published: November 2013

In the first academic genealogy session, held at the 153rd meeting of the Acoustical Society of America in Salt Lake City in 2007, David T. Blackstock displayed a poster detailing the Harvard academic tree leading back to Helmholtz [J. Acoust. Soc. Am. 121(5, Pt. 2), (2007)]. David also included the tree going up and discussed his Ph.D. and M.S. students. The author of this poster, Bart Lipkens, was one of David’s Ph.D. students. I was a faculty at Virginia Commonwealth University for two years, where I had one Ph.D. student, Shaozeng Dong. I then became a faculty at a predominantly undergraduate teaching institution, Western New England University in Springfield, Massachusetts. Western New England offers M.S. programs but limited Ph.D. opportunities. Even though my efforts are primarily focused on undergraduate teaching, I continue an acoustics research program, built mostly around M.S. and undergraduate students through a very active program of REUs (research experiences for undergraduates). This program has led several students to pursue further graduate education and careers in acoustics. A review of these students will be given.
Flute measurements in a physics of music lab
Authors: Worland Randy
Published: November 2013

Physics of Music students often benefit from laboratory exercises that make use of real musical instruments, in addition to the more traditional labs that are designed to illustrate physical principles as simply as possible. These “real instrument” labs help bridge the gap between idealized cases and the musical instruments the students are familiar with. Modern woodwinds are particularly challenging in this regard due to the complex set of keys, levers, and mechanical linkages that tend to obscure the underlying acoustics of these instruments. Among the woodwinds, the flute is relatively simple, both mechanically and acoustically, and thus provides an excellent subject for a real world woodwind study. Laboratory exercises are described in which the flute’s tone hole locations and diameters are measured. The data are analyzed in terms of the acoustics of open cylindrical tubes, revealing the logical order behind the spacing and use of the holes to play the lowest chromatic octave, as well as the higher registers of the flute. The measurement techniques and analysis are presented along with the pedagogical role of the experiment.
A carillon bell laboratory in an introductory physics of music class
Authors: Dostal Jack
Published: November 2013

The Physics of Music is a lecture and laboratory class which satisfies a quantitative physical science requirement. It is open to students of all majors. Students taking the class may or may not have musical backgrounds, and generally are not majors in the physical sciences. In this laboratory exercise, students record sounds of the bells of the Harris Carillon in the tower of WFU’s Wait Chapel. Using Audacity and other software, students generate frequency spectra of different bells. The prominent presence of minor thirds in the spectrum makes for a useful comparison between spectra of bells and typical concert instruments. In this lab, students identify spectral features of individual bells, find similarities and differences between different bell spectra, and observe the decay of spectral features over time. In this talk, I will describe some of the activities performed by the students in the lab and comment on some of the challenges of performing this laboratory exercise with students of varied musical and scientific backgrounds.
Types of soundwalks and their applications in soundscape design
Authors: Siebein Gary W. , Siebein Keely M. , Siebein Gary
Published: November 2013

Seven types of soundwalks are described with examples of the data obtained and the application of each to a case study project. The first type is one where an observer walks through an environment and just listens to get an introduction to the environment or an inspiration for later work. The second type is one where the observer walks with a group of stakeholders to listen to or elicit observations about the environment. The third type of soundwalk is one in which qualitative data in the form of questionnaire responses or quantitative data in the form of sound level measurements or recordings are made. The fourth type is an undercover soundwalk where observations or data are recorded in a way that the observer is not identified as one is not a normal participant in the soundscape. The fifth type is one where stakeholders experience an existing environment that has elements being considered for use in their project. A sixth type of soundwalk is one that occurs in a computer simulation where one experiences a virtual environment. The seventh type is one that combines two or more of the individual types of soundwalks in a composite soundwalk.
Combining elements of the soundscape—Lessons from the recording studio
Authors: Case Alex
Published: November 2013

So many soundscapes—found, archived, preserved, or composed—consist of multiple sound elements. The interaction among these individual sounds can conflict and obscure, or complement and harmonize. The creation of sound recordings through the multitrack production process offers a point of view into how an overall soundscape can be successfully created, and its multiple sounds effectively orchestrated.
Structural equation modeling of soundscape perception based on urban contexts
Authors: Jeon Jin Yong , Hong Joo Young
Published: November 2013

The aim of this study is to explore influential factors on urban soundscape perception. Objective and subjective assessments of the soundscapes in various urban spaces were conducted to characterize soundscape contexts using soundwalks. Evaluations were conducted at 21 locations, including residential, office, park, and commercial spaces in Seoul: the participants assessed their perceptions of both sound and landscape environments. In addition, laboratory experiments using audio-visual stimuli were carried out to validate the dominant soundscape factors derived from the soundwalks. From the results, a perception model of urban soundscapes consisting of physical and subjective indicators was suggested using structural equation modeling.
Standards vs off-standards in the soundscape design process
Authors: Bauer Juergen
Published: November 2013

Standards are widely acknowledged agreements that make issues and procedures comparable, compatible, and safe. Standards, therefore, help speak a common language and are considered a means of quality assurance, particularly in the field of design. However, in respect to Soundscape research being regarded as a subject of acoustic ecology, there is a limitation: How can standardization assess and evaluate Soundscape entities in an appropriate way which takes ecologic diversity into account? Can descriptors be found which indicate Soundscape qualities other than by measured sound pressure levels, or by surveyed human perception of pleasantness and annoyance? While it is fully acknowledged that these indicators will continue to play a key role in the discussion on Soundscape quality, they fail to address the distinction and the specific “atmosphere” of a specific Soundscape entity. “Atmosphere,” as suggested by Gernot Boehme (1993), is “the inbetween” of environmental qualities and human states. By this definition, a specific “atmosphere” is bound to a specific space. This paper explores the potential of using descriptors of “atmosphere,” such as in the architectural and urban design process, to help further expand the specification of Soundscape standards, but also to exploit the concept of off-standard Soundscape solutions.
Psychoacoustics triggering the soundscape standardization
Authors: Genuit Klaus , Schulte-Fortkamp Brigitte , Fiebig André
Published: November 2013

Before the start of COST Action TD0804 (network on soundscape of European cities and landscapes) in 2009, the Working Group 54 of ISO/TC 43/SC 1 was established to start consideration of a standardized protocol for assessment of soundscape. The progress is slow since many different protocols are available, which make it difficult to define a harmonized protocol reflecting diverse requirements. No protocol covers all needs, which is characteristic in research dealing with quality of life, where space, social and built environment and culture are often very different. Unfortunately, there is still a lack of open-mindedness to use new soundscape techniques, e.g., in noise action plans and for the protection of quiet areas. The situation differs, however, broadly from country to country. The Working Group 54 of ISO/TC 43/SC 1 works on reaching consensus to provide the necessary stimulus for further worldwide progress. Currently, the ISO WG 54 is working on measurement procedures and techniques that will trigger the procedures in soundscape research. Psychoacoustics and explorative interviews play a major role, and the triangulation of the respective data is offering consolidated findings. This paper will present related techniques and will discuss their advantages.
Educating for soundscape design
Authors: Elizondo - Garza Fernando J.
Published: November 2013

The development of standardization on soundscapes leads to produce the need of experts and designers of acoustic spaces that be educated in a wide cultural and technological base. Although there is nothing new for well educated acousticians, we cannot forget that people involved in architectural or noise control problems are not always acousticians, thus they do not have a full scope of the possible solutions neither of the listeners expectations about sound environment. Engineering, technology, economics, society, diversity, education, psychology, communication, interdisciplinarity, workgroups, ethics, and other educational issues necessary for soundscapes design are discussed in this paper. Many of these aspects are difficult to be included in the curricula directly, so they must be handled as homework and extracurricular activities, under the direction of an acoustics professor interested in the generation of better sound spaces for the welfare of society.
Recent developments in an old problem: Helping communities deal with noise
Authors: Suter Alice H. , Hammer Monica S.
Published: November 2013

This presentation will suggest areas where professionals in acoustics can collaborate with policy makers to remediate their noise problems and promote an environment more conducive to the public health and welfare. Research over recent years has confirmed and elucidated the adverse effects of noise on health in ways that earlier cross-sectional studies had indicated, but with the added power of a prospective approach and extensive controls. The implications of these findings should be considered widespread and serious. Lacking a coordinated federal program, U.S. Cities and counties are attempting to grapple with their noise issues, without federal support and often with limited technical expertise. Despite passage of the Noise Control Act of 1972 (subsequently de-funded), millions of Americans remain exposed to levels of environmental noise that are harmful to their health and welfare.
Offshore pile driving noise—Prediction through comprehensive model development
Authors: Ruhnau Marcel , Lippert Tristan , Heitmann Kristof , Lippert Stephan , von Estorff Otto
Published: November 2013

Offshore wind energy is one of the most potent among renewables and thus the worldwide number of offshore wind turbines increases rapidly. The foundations of the wind turbines are typically fastened to the seabed by impact pile driving, which comes along with a significant amount of waterborne noise. To protect the marine biosphere, the use of noise mitigation systems, like bubble curtains or cofferdams, may become necessary. In this context, the model-based prediction of underwater sound pressure levels as well as the design and optimization of effective sound mitigation measures by using numerical models is one of today’s challenges. The current work presents a modeling approach that consists of a near field finite element model and a far field propagation model. Furthermore, it has been found necessary to generate a benchmark to allow for a qualitative and quantitative comparison between the manifold modeling approaches that are currently developed at various institutes and companies.
Model for underwater noise radiated by submerged piles
Authors: Hay Todd , Ilinskii Yurii A. , Lee Kevin M. , Zabolotskaya Evgenia A. , Hamilton Mark F.
Published: November 2013

There is concern that underwater noise generated by marine construction activities and radiated by towers supporting offshore wind turbines may disturb marine mammals, or interfere with passive sensors and communication equipment. In order to understand these effects a semi-analytic frequency-domain model was developed previously for the sound radiated in the water column by a pulsating cylindrical structure embedded in horizontally stratified layers of viscoelastic sediment. This model was in turn coupled to a parabolic equation code for long-range propagation over range-dependent environments [Hay et al., J. Acoust. Soc. Am. 133, 3396 (2013)]. A time-domain version of this model is now presented which enables simulation of impulsive sound sources such as those due to underwater pile driving, and pulsed tonal sources appropriate for use in a finite-sized laboratory tank. In order to validate the model a scaled physical model, consisting of a laboratory tank and metallic cylindrical tube driven in the high kilohertz frequency range, was constructed. Simulations will be presented for a variety of sound sources, and preliminary comparisons with measurements from the scaled model experiments will be made.
Numerical simulations of hydrosound and ground vibrations during offshore pile driving
Authors: Kuhn Christian
Published: November 2013

Most foundations for offshore wind turbines are currently constructed with monopiles. During the installation, the monopile is driven into the ground using a hydraulic hammer. A pressure wave is induced into the pile and passes through the pile shaft which as a result expands radially and induces underwater noise in the surrounding water. Similarly, a shock wave is introduced into the ground which propagates there spherical. In a numerical simulation the driving process is simulated. The focus is on the energy radiated from the pile into the surrounding water-/ground continuum. As part of a research project, an offshore test was performed. During this, the underwater noise in the water as well as the soil vibrations on the seabed were measured. The numerical results are compared with these measurement results.
Toward a standard for measurement of underwater noise from marine impact piling
Authors: Robinson Stephen , de Jong Christ , Mueller Andreas , Theobald Pete
Published: November 2013

Marine impact piling is a significant source of low-frequency impulsive noise in the ocean and is typically used to position piled foundations in relatively shallow water for offshore construction, for example, offshore wind farms, bridge supports, etc. However, there are currently no international standards to define appropriate measurement methodologies, and there is a need to underpin incipient regulation with appropriate measurement standards. In the scientific literature, attempts to report the measured noise levels can be difficult to compare because different metrics are often used (peak-to-peak pressure, rms pressure, sound exposure level, etc). Furthermore, simple assumptions about equivalent point sources are often used in measurements and modeling without sufficient validation. Agreed acoustic metrics and a common way of deriving a meaningful measure of source output are urgently required. This paper describes work to address this need within the International Standards Organisation, specifically Working Group 3 of Technical Committee 43, Sub-Committee 3 (ISO TC43 SC3 WG3). Work to develop a new standard builds upon the expertise already gained by researchers in a number of countries (for example, United Kingdom, Netherlands, and Germany). A description is given of the methodology currently proposed, and the process for engagement with experts within different countries.
Results from background noise measurements in the North Sea
Authors: Schuster Max
Published: November 2013

In Germany, 12.8 GW offshore wind power shall be installed until 2023, which involves that at minimum 200 wind turbines need to be erected each year. As the majority of the turbines’ foundations are based pile driving vast amounts of high level impulsive noise are introduced into the North- and Baltic Sea. Until today, research on pile driving noise largely focuses on sound propagation and noise mitigation in close vicinity of the pile. Further effects of impulsive noise in larger distances over 10 km are rather unknown due to a lack of knowledge on the propagation and on the effects of noise at levels below injury. The German Agency for Nature Conservation has founded a campaign to measure underwater noise in the marine protected areas of the German EEZ. In this course, 10 noise recorders are simultaneously deployed in the large protected area Sylt Outer Reef. At least three wind farms are to be installed in the area’s vicinity; therefore, recordings of background noise during the installation phase allow a systematic investigation of impulsive noise propagation over large distances. Results in time domain and in frequency domain are compared with results from commonly available calculation codes.
Transmission loss for vibratory pile driving in shallow water: Modeling and field measurements for a Puget Sound location
Authors: Farrell Dara M. , Dahl Peter H.
Published: November 2013

Measurements of the underwater noise from vibratory pile driving were collected at a marine construction site in January 2013, during which 0.76 m steel piles were driven in shallow water (less than 10 m). The sound field was simultaneously measured at three locations at distances 200 m (1 hydrophone) and 400 m (2 hydrophones) from the pile driving location and roughly 150 m to 300 m from the shore. In the Practical Spreading Model (PSM), transmission loss is 15 log10(R/R0): R is the range to which TL is calculated, and R0 is the range for a close range measurement, typically O(10 m) from the source. Models such as the PSM that do not account for bathymetric or sediment properties could not be expected to predict the anomalously high transmission loss (TL) that was observed between the 200 m location and one of the 400 m locations. Important bathymetric features (of order 10 m in range, 1 m in depth) and sedimentary properties for the area were incorporated into a Parabolic Equation model; modeled TL was compared to observed TL for third octave bands. Using a Geographic Information System tool, modeled TL was visualized for the area. [Work supported by Washington Sea Grant.]
Depth dependence of the intensity vector from impact pile driving
Authors: Dall'Osto David R. , Dahl Peter H.
Published: November 2013

The direction of the time-integrated acoustic intensity vector defines active intensity streamlines which are perpendicular to this vector. For impact pile driving, these intensity streamlines depend on both depth and time. The time-integrated intensity vector (active intensity) has been shown to change direction over the initial downward traveling Mach cone, the upward traveling reflection of this from the bottom of the pile, and subsequent downward traveling reflection from the top of the pile, referred to as phases in Dahl and Reinhall [J. Acoust. Soc. Am. 134, EL1 (2013)]. In this study, vertical line array data are used to demonstrate the depth dependence of the active intensity vector during each of the three phases. The vertical component of the active intensity is approximated between each pair of neighboring hydrophones by finite difference methods. A numerical approach based on parabolic wave equation simulations [Reinhall and Dahl, J. Acoust. Soc. Am. 130, 1209 (2011)] is modified here and used to construct theoretical intensity streamlines, motivated by those depicted in Zampolli et al. [Acoust. Soc. Am. 133, 72 (2013)]. These intensity streamlines are validated by the experimental measurements. Energy propagation through the water column and the sediment-water interface is also discussed.
Coupled membranes with doubly negative mass density and bulk modulus
Authors: Sheng Ping
Published: November 2013

We present a structurally and conceptually simple acoustic double negative metamaterial comprising two coupled membranes [Phys. Rev. Lett. 110, 134301 (2013)]. Owing to its symmetry, the system can generate both monopolar and dipolar resonances that are separately tunable, thereby making broadband double negativity possible. A homogenization scheme is implemented that enables the exact characterization of our metamaterial by the effective mass density and bulk modulus even beyond the usual long-wavelength regime, with the measured displacement fields on the sample’s surfaces as inputs. Double negativity is achieved in the frequency range of 520–830 Hz. Transmission and reflection predictions using effective parameters are shown to agree remarkably well with the experiment. Work done in collaboration with M. Yang, G. C. Ma, and Z. Y. Yang.
Acoustic cloaking for airborne sound based on inclusions of rigid scatterers
Authors: Garcia-Chocano Victor Manuel , Cervera Francisco , Díaz-Rubio Ana , Climente Alfonso , Torrent Daniel , Sánchez-Dehesa José
Published: November 2013

Acoustic cloaking is a phenomenon whose physical realization depends on the ability of designing metamaterials with the appropriate parameters. When dealing with airborne sound almost any solid behaves as an acoustically rigid material, so cloaks based on rigid scatterers are here studied. Since these structures are not able to increase the effective sound speed with respect to the background, additional mechanisms should be introduced to allow this effect. Here we will report an acoustic cloak based on temperature gradients. Another possibility of hiding objects from an external sound source consists of using a set of external layers that cancels the scattered field by such objects at selected frequencies. We present the practical realization of this approach for 2D and 3D structures. [Work supported by MINECO from Spain and ONR from United States.]
An effective Cosserat continuum model for waves in a material with microstructure
Authors: Barbone Paul E.
Published: November 2013

The effective acoustic properties of a medium can be tailored by appropriately designing its microstructural components. The effective properties of a material may be generally defined as those that describe the limiting case where the wavelength of propagation is infinite compared to the characteristic scale of the microstructure. Generally, the limit of vanishingly small microstructural scale in an elastic medium results in an effective medium that is again elastic. In this contribution, we give an example for which the above limit results not in an effective elastic medium, but rather, an effective Cosserat medium. We briefly review the properties of Cosserat continua, provide a basic derivation of their fundamental equations of motion, and interpret the continuum properties in terms of the microstructural elements.
Nonlinearity parameters B/A and C/A and wave equation for heterogeneous media containing negative stiffness inclusions
Authors: Konarski Stephanie G. , Haberman Michael R. , Hamilton Mark F.
Published: November 2013

This work considers nonlinear propagation in a medium consisting of a low volume fraction of metamaterial inclusions dispersed in a fluid-like material. The metamaterial inclusions of interest are assumed to possess non-monotonic stress-strain constitutive relations, which results in regimes of negative stiffness. For modeling purposes, the constitutive relation for these inclusions is approximated with an expansion to third order in volume strain with coefficients that can be tuned with the geometry of the metamaterial structure and ambient pressure. A far-reaching goal of this research is to model the hysteretic response of the heterogeneous medium resulting from metamaterial inclusion snapping events and the associated effect on acoustic disturbances that cycle through regimes of both positive and negative stiffness. As an initial step, results are presented here for small but finite-amplitude disturbances limited to local regions of the constitutive relation. For this case, the quadratic and cubic nonlinearity parameters B/A and C/A, respectively, as traditionally defined for fluids are obtained. An evolution equation with both quadratic and cubic nonlinearity is also obtained. Numerical solutions of the evolution equation illustrate nonlinear waveform distortion as a function of the volume fraction and constitutive behavior of the inclusions. [Work supported by ARL:UT McKinney Fellowship in Acoustics.]
Two-dimensional broadband acoustic black hole for underwater applications
Authors: Naify Christina J. , Martin Theodore P. , Layman Christopher N. , Calvo David C. , Orris Gregory J.
Published: November 2013

Transformation acoustics using sub-wavelength elements to obtain homogenized properties has been utilized increasingly in recent years to manipulate the propagation of acoustic waves. Gradient index (GRIN) lenses are designed by varying local properties of the elements through a given geometry for a variety of devices including focusing lenses and black holes. This study presents a cylindrical, two-dimensional acoustic black hole for underwater applications. The black hole designed focuses acoustic energy to the center of the cylinder using a radially decreasing sound speed profile. An absorbing core then prevents scattering of the acoustic waves into the surrounding fluid. Transformation acoustics was used to design the index gradient through the black hole structure and multiple scattering theory (MST) was used to predict the scattering profile over a broadband range of frequencies. The black hole was constructed of concentric rings of silicone rubber cylinders, which behave as effective fluids in a multiple scattering configuration. Experimental realization of the black hole structure was fabricated and analyzed with measured pressure intensity agreeing with predicted results. [Work sponsored by the Office of Naval Research.]
Negative refraction and focusing of acoustic waves using a foam-like metallic structure
Authors: Norris Andrew , Vasseur Jérôme O. , Haw Gérard , Croënne Charles , Haumesser Lionel , Hladky-Hennion Anne-Christine
Published: November 2013

A phononic crystal (PC) slab made of a single metallic phase is shown, theoretically and experimentally, to display perfect negative index matching and focusing capability in water. The PC slab is a centimeter scale air-filled foam-like metal structure arranged in a regular hexagonal lattice in which the acoustic energy is mediated via the metal lattice. The structure has the density and longitudinal velocity of water at low frequency. The negative index property arises from an isolated higher frequency branch of the dispersion curves corresponding to a mode that couples to incident acoustic waves in water. This band intercepts the sonic line at a frequency in the ultrasonic range, which leads to perfect index matching. The metallic structure is consequently a candidate for the negative refraction of incident longitudinal waves, and the realization of flat superlenses which can focus acoustic waves with a resolution lower than the diffraction limit.
Effective acoustic response and spectral representation
Authors: Esquivel-Sirvent Raul
Published: November 2013

The problem of finding an effective or average acoustic properties of inhomogeneous materials has been treated extensively in connexion with problems of porous media, rock physics and composite materials. Recently, there has been a renewed interest due to the potential applications of acoustic metamaterials. There are different techniques for finding effective acoustic properties. These range from simple averaging techniques, to variational methods, to coherent phase approximations. There is not a unique method for finding effective properties. In the case of dielectric materials, there are at least thirteen procedures reported. In this work, we present the acoustic version of the spectral representation of effective media, first developed to find dielectric effective properties. This method has the advantage that it separates the geometric contribution from the physical property to be calculated, in our case the acoustic impedance. The method is based on a Green's function solution of the acoustic wave equation and finding the effective properties is done by calculating the poles of the so called spectral function. Furthermore, we show that any effective medium model that can be described in the spectral representation satisfies the Kramers-Kronig relations. Numerical examples and comparisons between the spectral representation and other existing procedures will be discussed.
A history of random vibration
Authors: Paez Thomas L.
Published: November 2013

Natural, random, dynamic environments are ubiquitous, and humans have observed them for millennia. Some random dynamic environments are earthquake ground motions, winds, ocean waves, rough roads, and acoustic pressure environments arising from thunder. Before people could easily conceptualize harmonic motions, they observed random, oscillatory environments. Today, random vibration can be mathematically modeled as the motion of a mechanical system excited by a random input. The mathematical theory of random vibration is essential to the realistic modeling of structural dynamic systems. This paper summarizes the work of some key contributors to the theory of random vibration from the time of Rayleigh and Einstein to the present. Among many other things, we describe the works of (1) Rayleigh, who, in the late nineteenth century introduced ideas about the representation of random signals as the superposition of random harmonics; (2) Schuster, who, in the late nineteenth and early twentieth centuries described, without taking its limit, the spectral density; (3) Einstein who, in 1905, wrote the first actual paper on the theory of random vibration (Brownian movement); and (4) Wiener who, in 1930, formally defined the spectral density. Several graphic examples are included.
Measurement of high amplitude relief valve noise during a full scale blowdown
Authors: Evans Neal
Published: November 2013

Dynamic pressure fluctuations inside a pipe were measured downstream of a pressure relief valve during a full scale blowdown test. Nitrogen gas flowed with a maximum rate of 33.5 kg/s through a 3 in.x4 in. relief valve generating a peak dynamic pressure level greater than 650 kPa and sustained levels of over 450 kPa (peak). An accurate estimate of valve-generated noise is necessary when predicting radiated noise and acoustic induced vibration, which has been shown to cause fatigue failures at welded discontinuities in piping systems downstream of high pressure drop devices. These failures can be hazardous and costly, particularly when the process involves hydrocarbons such as natural gas. The measured level is compared to existing noise calculation techniques which appear to under-predict the generated noise.