bluuebunny/crossref_metadata_2025 huggingface dataset:
Classification of mysticete sounds using machine learning techniques
Authors: Halkias Xanadu C. , Paris Sébastien , Glotin Hervé
Published: November 2013

Automatic classification of mysticete sounds has long been a challenging task in the bioacoustics field. The unknown statistical properties of the signals as well as the use of different recording apparatus and low signal-to-noise ratio conditions often lead to non-optimal systems. The goal of this paper is to design methods for the automatic classification of mysticete sounds using a restricted Boltzmann machine and a sparse auto-encoder that are widely used in the field of artificial intelligence. Experiments on five species of mysticetes are presented. The different methods are employed on the subset of species whose frequency range overlaps, as well as in all five species' calls. Moreover, results are offered with and without the use of a noise class. Overall, the systems are able to achieve an average classification accuracy of over 69% (with noise) and 80% (without noise) given the different architectures.
Acoustic scattering from a double periodically bulkheaded and ribbed finite cylindrical shell
Authors: Pan An , Fan Jun , Wang Bin
Published: November 2013

The sound scattering from a finite vacuumed cylindrical shell simultaneously loaded with the bulkheads and the ribs are studied. The motions of the shell are described by the Donnell equations. Each rib is modeled as a rod of circular curvature where only the normal force is applied. The motions of the bulkheads are decomposed into the out-plate bending motions and the in-plate extensional motions, which are independent of each other. The backscattered sound field is analyzed via the frequency-angle spectra. Compared against the backscattered sound from a ribbed cylindrical shell, the Bloch-Floquet waves disappear at low frequencies but still exist at mid and high frequencies. The Bragg scattering excited by the ribs is unchanged at mid and high frequencies. Besides the ribs' Bloch-Floquet waves and Bragg scattering, there exists the Bragg scattering excited by the bulkheads. The backscattering from a cylindrical shell loaded with just the bulkheads is calculated. When the spacing and the thickness of the bulkheads are equal to those of the ribs, the crests of the Bragg scattering and the Bloch-Floquet waves on the frequency-angle spectra are almost the same as those of the ribbed cylindrical shell. The resonances of the bulkheads are also excited in this case.
Coupled wedge waves
Authors: Abell Bradley C. , Pyrak-Nolte Laura J.
Published: November 2013

The interface between two wedges can be treated as a displacement discontinuity characterized by elastic stiffnesses. By representing the boundary between the two quarter-spaces as a displacement discontinuity, coupled wedge waves were determined theoretically to be dispersive and to depend on the specific stiffness of the non-welded contact between the two wedges. Laboratory experiments on isotropic and anisotropic aluminum confirmed the theoretical prediction that the velocity of coupled wedge waves, for a non-welded interface, ranged continuously from the single wedge wave velocity at low stress to the Rayleigh velocity as the load applied normal to the interface was increased. Elastic waves propagating along the coupled wedges of two quarter-spaces in non-welded contact are found to exist theoretically even when the material properties of the two quarter-spaces are the same.
Investigation of sonar transponders for offshore wind farms: Modeling approach, experimental setup, and results
Authors: Fricke Moritz B. , Rolfes Raimund
Published: November 2013

The installation of offshore wind farms in the German Exclusive Economic Zone requires the deployment of sonar transponders to prevent collisions with submarines. The general requirements for these systems have been previously worked out by the Research Department for Underwater Acoustics and Marine Geophysics of the Bundeswehr. In this article, the major results of the research project “Investigation of Sonar Transponders for Offshore Wind Farms” are presented. For theoretical investigations a hybrid approach was implemented using the boundary element method to calculate the source directivity and a three-dimensional ray-tracing algorithm to estimate the transmission loss. The angle-dependence of the sound field as well as the weather-dependence of the transmission loss are compared to experimental results gathered at the offshore wind farm alpha ventus, located 45 km north of the island Borkum. While theoretical and experimental results are in general agreement, the implemented model slightly underestimates scattering at the rough sea surface. It is found that the source level of 200 dB re 1 μPa at 1 m is adequate to satisfy the detectability of the warning sequence at distances up to 2 NM (≈3.7 km) within a horizontal sector of ±60° if realistic assumptions about signal-processing and noise are made. An arrangement to enlarge the angular coverage is discussed.
Description of sounds associated with Sowerby's beaked whales (Mesoplodon bidens) in the western North Atlantic Ocean
Authors: Cholewiak Danielle , Baumann-Pickering Simone , Van Parijs Sofie
Published: November 2013

Several groups of Sowerby's beaked whales (Mesoplodon bidens) were encountered on July 4, 2011, during a shipboard cetacean survey conducted off the eastern seaboard of the United States. Acoustic recordings were collected using a three-element towed hydrophone array. Many echolocation clicks were recorded during the encounter, but no tonal sounds were detected. A total of 2969 echolocation clicks were included in analyses of frequency and temporal characteristics. A Gaussian mixture model with four mixtures was fitted to the histogram of peak frequencies; four subsets of clicks were designated. The majority of clicks (n = 2048) contained a median peak frequency of 33 kHz, while the others contained a median peak frequency of 25 kHz (n = 324), 51 kHz (n = 304), or 67 kHz (n = 293). Most clicks did not contain a clear frequency-modulated upsweep, though some clicks exhibited a slight sweep from 30–36 kHz. Seven burst pulses were detected in the encounter, two of which were of high enough quality for detailed analysis. The acoustic characteristics of Sowerby's beaked whales have not previously been described; the current study will facilitate incorporation of these data into passive acoustic monitoring programs in the North Atlantic Ocean.
Clarity in communication: “Clear” speech authenticity and lexical neighborhood density effects in speech production and perception
Authors: Scarborough Rebecca , Zellou Georgia
Published: November 2013

Speech produced in the context of real or imagined communicative difficulties is characterized by hyperarticulation. Phonological neighborhood density (ND) conditions similar patterns in production: Words with many neighbors are hyperarticulated relative to words with fewer; Hi ND words also show greater coarticulation than Lo ND words [e.g., Scarborough, R. (2012). “Lexical similarity and speech production: Neighborhoods for nonwords,” Lingua 122(2), 164–176]. Coarticulatory properties of “clear speech” are more variable across studies. This study examined hyperarticulation and nasal coarticulation across five real and simulated clear speech contexts and two neighborhood conditions, and investigated consequences of these details for word perception. The data revealed a continuum of (attempted) clarity, though real listener-directed speech (Real) differed from all of the simulated styles. Like the clearest simulated-context speech (spoken “as if to someone hard-of-hearing”—HOH), Real had greater hyperarticulation than other conditions. However, Real had the greatest coarticulatory nasality while HOH had the least. Lexical decisions were faster for words from Real than from HOH, indicating that speech produced in real communicative contexts (with hyperarticulation and increased coarticulation) was perceptually better than simulated clear speech. Hi ND words patterned with Real in production, and Real Hi ND words were clear enough to overcome the dense neighborhood disadvantage.
Trumpet mouthpiece manufacturing and tone quality
Authors: Zicari Massimo , MacRitchie Jennifer , Ghirlanda Lorenzo , Vanchieri Alberto , Montorfano Davide , Barbato Maurizio C. , Soldini Emiliano
Published: November 2013

This article investigates the relationship between the shape of the mouthpiece and its acoustical properties in brass instruments. The hypothesis is that not only different volumes but also particular cup shapes affect the embouchure and the tone quality in both a physical and perceivable way. Three professional trumpet players were involved, and two different internal cup contours characterized by a “U” and a “V” shape with two types of throat junction (round and sharp) were chosen, based on a Vincent Bach 1 [1/2] C medium mouthpiece. A third intermediate contour was designed as a combination of these. Over 600 sound samples were produced under controlled conditions, the study involving four different stages: (1) Simulation of air-flow, (2) analysis of the sound spectra, (3) study of the players' subjective responses, and (4) perceptual analysis of their timbral differences. Results confirm the U shape is characterized by a stronger air recirculation and produces stronger spectral components above 8 kHz, compared to the V shape. A round throat junction may also be preferable to a sharp one in terms of playability. There is moderate agreement on the aural perception of these differences although the verbal attributes used to qualify these are not shared.
Sound field reproduction as an equivalent acoustical scattering problem
Authors: Fazi Filippo Maria , Nelson Philip A.
Published: November 2013

Given a continuous distribution of acoustic sources, the determination of the source strength that ensures the synthesis of a desired sound field is shown to be identical to the solution of an equivalent acoustic scattering problem. The paper begins with the presentation of the general theory that underpins sound field reproduction with secondary sources continuously arranged on the boundary of the reproduction region. The process of reproduction by a continuous source distribution is modeled by means of an integral operator (the single layer potential). It is then shown how the solution of the sound reproduction problem corresponds to that of an equivalent scattering problem. Analytical solutions are computed for two specific instances of this problem, involving, respectively, the use of a secondary source distribution in spherical and planar geometries. The results are shown to be the same as those obtained with analyses based on High Order Ambisonics and Wave Field Synthesis, respectively, thus bringing to light a fundamental analogy between these two methods of sound reproduction. Finally, it is shown how the physical optics (Kirchhoff) approximation enables the derivation of a high-frequency simplification for the problem under consideration, this in turn being related to the secondary source selection criterion reported in the literature on Wave Field Synthesis.
The effect of two different rooms on acoustical and perceptual measures of mixed choir sound
Authors: Hom Kathryn S.
Published: November 2013

The purpose of this study was to explore the effect of two different rooms (choir rehearsal room, performance hall) on acoustical (LTAS, one-third octave bands) and perceptual (singer [N = 11] survey, listener [N = 33] survey, and Pitch Analyzer 2.1) measures of soprano, alto, tenor, and bass (SATB) choir sound. Primary findings of this investigation indicated: (a) significant differences in spectral energy comparisons of choir sound between rooms, (b) choristers’ perceptions of hearing and monitoring their own voices differed significantly depending on room, (c) most choristers (82%) perceived that the choir performed best within the Performance Hall, (d) perceived pitch of selected sung vowels within recordings differed significantly based on room conditions, (e) 97% of listeners perceived a difference in choir sound between room recordings, and (f) most listeners (91%) indicated preference for the Rehearsal Room recording.
The maximum intelligible range of the unamplified human voice
Authors: Boren Braxton B. , Roginska Agnieszka
Published: November 2013

The Anglican preacher George Whitefield preached to some of the largest reported crowds in recent history during the Methodist revivals in 18th century London. Benjamin Franklin later performed an auditory experiment in Philadelphia from which he estimated Whitefield could be heard by 30,000 listeners at once. Using the data from Franklin’s experiment and acoustic model of colonial Philadelphia, Whitefield’s on-axis averaged sound pressure level at one meter has been calculated to be about 90 dBA, consistent with the loudest values measured from trained vocalists today. Using period maps and topological data, acoustic models have been constructed of the sites of Whitefield’s largest crowds in London, using a human voice source with the projected SPL for Whitefield’s preaching voice. Based on the total audience area whose speech transmission index value is greater than that at Franklin’s position in the Philadelphia experiment, the total intelligible audience area can be calculated. Using Franklin’s own crowd density calculations, this method allows estimates of the maximum amount of listeners that could hear Whitefield’s voice under different environmental conditions and provides a better maximum estimate for the free-field intelligible range of the unamplified human voice.
Temporal and spatial trends in acoustic detections of delphinid species around Niihau, Hawaii
Authors: Oswald Julie N. , Au Whitlow W. L. , Lammers Marc O. , Richlen Michael F. , Norris Thomas F.
Published: November 2013

Passive acoustic monitoring using seafloor-mounted recorders allows cetacean occurrence to be examined over time and space. Four ecological acoustic recorders (EARs) were moored around the Hawaiian island of Niihau in summer/fall (July—November) 2011, and winter/spring (January—May) 2012. Delphinid whistle “detections” (a proxy for schools) were identified and characterized. Whistles were identified to species using a random forest classifier trained with whistles recorded from seven species (Globicephala macrorhynchus, Pseudorca crassidens, Stenella attenuata, S. coeruleoalba, S. longirostris, Steno bredanensis, and Tursiops truncatus) in the tropical Pacific Ocean. The highest number of detections per day occurred during summer/fall at all sites. All species except for G. macrorhynchus were detected at every site during both deployments. No single species dominated the detections at any site, with the exception of Stenella longirostris at the Pueo Point site during summer/fall (53% of detections). Pseudorca crassidens, a species of particular management/conservation interest due to small population sizes, were detected most frequently (18% of detections) at the Niihau NW site during summer/fall and least frequently (7% of detections) at the Pueo Point site during summer/fall. Understanding trends in species composition provides insight into how species use different habitats and aids in management efforts.
Contribution of iceberg sounds to the ambient noise budget in the South Pacific Ocean
Authors: Matsumoto Haru , Bohnenstiehl Del , Dziak Robert , Haxel Joe , Park Minkyu , Lee Won-Sang , Lau Tai-Kwan , Fowler Matt
Published: November 2013

On May 2002, C19, a 5500 km2 iceberg calved from the Ross Ice Shelf, eventually drifting eastward into the open Pacific Ocean by 2008. As it sailed into warmer waters, thermal and wind stresses caused the iceberg to crack and break apart. These resulting “icequakes” projected wideband acoustic energy into the water column, influencing the regional ambient noise environment. Icequake noise was persistent and strong enough to be observed by NOAA’s eastern equatorial Pacific moored hydrophone (EEP-NW at 8N, 110W) as well as the hydroacoustic station of International Monitoring System (IMS) on Juan Fernandez Island (H03N at 33.44S, 78.91W). Elevated noise levels (maximum of ~+3 dB at NOAA’s EEP and ~+7 dB at IMS H03N hydrophones) were observed by both stations from early 2008 when C19a first appeared in the Pacific until it drifted into the Atlantic Ocean in early 2009. C19a’s icequake and calving activity was also most frequent during this same period. Seasonal changes and long-term trends in ambient noise levels at NOAA’s EEP-NW acoustic mooring (1996–2009) and IMS Juan Fernandez (2003–2010 years) and the unique acoustic role icebergs play in the Southern Ocean will be presented.
Single microbubbles vibrations measured with an “acoustical camera"
Authors: Renaud Guillaume , Bosch Johan , van der Steen Antonius , de Jong Nico
Published: November 2013

Measuring and understanding the nonlinear vibrations of contrast agent microbubbles in response to an ultrasound wave is essential to optimize the technique employed by an ultrasound scanner to distinguish microbubbles from tissue. In this context, an acoustical method was developed to retrieve the radial response of single microbubbles to a pressure wave by means of a low-amplitude probing wave. If the frequency of the latter is much higher than the spherical resonance frequency of the microbubble (typically between 1 and 10 MHz), the relative amplitude modulation (induced by a pressure wave) in the signal scattered in response to the probing wave is quasi-equal to the radial strain (i.e., relative variation in radius) induced by the pressure wave. A reference response to the probing wave acquired before and after the transmission of the pressure wave allows us to reveal asymmetry in microbubble oscillations. Although efficient nonlinear wave interaction is well known in bubbly liquids, we demonstrated that such an “acoustical camera” can extract quantitative information (the radius as function of time) on single bubble vibrations by analyzing the nonlinear coupling between two ultrasound waves.
Transcranial bubble activity mapping for therapy and imaging
Authors: O’Reilly Meaghan A. , Jones Ryan M. , Hynynen Kullervo
Published: November 2013

Bubble-mediated ultrasound therapies in the brain, such as targeted disruption of the blood-brain barrier (BBB) or cavitation-enhanced stroke treatments, are being increasingly investigated due to their potential to revolutionize the treatment of brain disorders. Due to the fact that they are non-thermal in nature, these therapies must be monitored by acoustic means to ensure efficacy and safety. A sparse, 128-element hemispherical receiver array (612 kHz) was integrated within a 306 kHz therapy array. The receiver arrangement was optimized through numerical simulations. The array was characterized on the benchtop to map the activity of bubbles in a tube phantom through an ex vivo human skullcap. In vivo the array was used to map bubble activity in small animal models during microbubble-mediated BBB disruption. The array was investigated as well for diagnostic purposes, imaging transcranial structures filled with very dilute concentrations of microbubbles. A spiral tube phantom with tube diameter of 255 µm was imaged, using a non-invasive phase correction technique, through an ex vivo human skullcap by mapping the activity from single bubbles. Applying super-resolution techniques, an image of the spiral phantom was produced that was comparable to an image obtained in a small-specimen micro CT.
Effects of contrast agents and high intensity focused ultrasound on tumor vascular perfusion
Authors: Phillips Linsey C. , Martin K. Heath , Gessner Ryan C. , Dayton Paul A.
Published: November 2013

High intensity focused ultrasound (HIFU) is a treatment modality which causes localized tissue ablation and is further enhanced when microbubble or nanodroplet contrast agents are present. While it is known that HIFU ablation results in diminished blood perfusion, these effects have never been mapped with high-resolution 3-D imaging. We aimed to longitudinally and volumetrically evaluate the effects of microbubbles and nanodroplets on tumor vessel perfusion following HIFU treatment. Rats bearing flank fibrosarcoma tumors were injected with 1.5 × 109 microbubbles (n = 3), nanodroplets (n = 3), or control/no-injection (n = 3) during targeted HIFU (125W/cm2, 1 MHz, 2 MPa, 10% duty cycle, 1 Hz PRF, 3 min). This HIFU power is ~99% less than clinical norms. Tumor perfusion was assessed by contrast enhanced 3-D acoustic angiography before, immediately following, and 72 h after HIFU application. No significant changes in tumor perfusion were observed when HIFU was applied with nanodroplet or control injections. However, HIFU in the presence of microbubbles resulted in a 66.2±15.2% (p < 0.05) reduction in perfused tumor volume. These results suggest that HIFU, when combined with microbubbles, can dramatically remodel tumor vasculature networks even at the low pressure used in this study. This could potentially enhance the safety of HIFU therapy.
Modeling the loss of echogenicity from ultrasound contrast agents
Authors: Bader Kenneth B. , Radhakrishnan Kirthi , Haworth Kevin J. , Raymond Jason L. , Huang Shao-Ling , Peng Tao , McPherson David D. , Holland Christy K.
Published: November 2013

Acoustically induced loss of echogenicity (LOE) from ultrasound contrast agents (UCAs) has been exploited in imaging techniques to improve delineation of pathology. Determination of the type of cavitation that accompanies LOE can be experimentally difficult to determine due to the complex microbubble activity elicited. A theoretical model has been derived to predict the LOE originating from rupture of the UCA shell, from stable cavitation, or from inertial cavitation. The predictions of the model for each cavitation phenomena will be compared to recent experimental LOE measurements of the lipid-based UCA Definity® and echogenic liposomes insonified by Doppler pulses from a clinical scanner. The backscatter coefficient was calculated for a population of UCAs exposed to 6-MHz pulsed ultrasound of duration 1.67μs—8.33 μs. The change in the total backscatter coefficient was used to predict the LOE. The size distribution of UCAs was adjusted according to the specific type of cavitation triggered by the ultrasound exposure. Comparison of the theoretical predictions and experimental measurements suggest that shell rupture is the dominant mechanism for LOE for both Definity® and echogenic liposomes. These results will be discussed in conjunction with a recently developed cavitation index to predict the LOE of UCAs.
Energy decay analysis in coupled volumes using an acoustic wave simulator
Authors: Chandak Anish , Antani Lakulish , Manocha Dinesh
Published: November 2013

The acoustics in coupled volumes present various challenges. For example, the sound energy decay curve is double-sloped indicating that a single reverberation time cannot be assigned to coupled volumes. Such a behavior depends on various factors like the aperture sizes between the coupled volumes, absorption coefficients of each volume, etc. Recently, many studies using computer simulation have been performed to better understand the acoustic behavior of coupled volumes. None of these studies perform full 3D acoustic wave simulation on coupled volumes as they are regarded as computationally expensive and limited to very small spaces. We perform acoustic wave simulation using a relatively new wave solver called adaptive rectangular decomposition (ARD). ARD is more accurate than geometric acoustics techniques. It has been demonstrated to provide reliable simulation results through comparison with measurement data in indoor and outdoor scenes. Furthermore, it is practical and can handle large acoustic spaces on a single desktop. In this study, we analyze energy decay curves in coupled volumes using ARD. We perform numerical simulation for various coupled volume configurations such as varying aperture sizes, absorption coefficients, etc., and present their decay curves for analysis.
Can wavelets solve the cocktail party?
Authors: Fischer Mark
Published: November 2013

There are many eco-systems that exist where avian populations are dense. In such environments, it is often the case that many different species may sing contemporaneously with significant overlap in the frequencies used by each. Work will be presented to support the hypothesis that wavelet processing allows an analog solution to this “cocktail party” problem.
Sparse representation classification of dolphin whistles using local binary patterns
Authors: Esfahanian Mahdi , Zhuang Hanqi , Erdol Nurgun
Published: November 2013

A sparse representation classifier (SRC) has been adapted and applied to spectrograms to identify bottlenose dolphin whistles by their types. The classifier that relies on near completeness of the training features renders their choice no longer crucial as long as criteria are met to assure signal sparsity. Signal sparsity is ensured via the employment of a robust, effective, and computationally simple local binary patterns (LBP) operator that eliminates the need for costly denoising and contour tracking operations. The performance of the proposed method is compared to classifier-feature combinations of the K-nearest neighbor (KNN) and support vector machine (SVM) classifiers, and feature vectors of time-frequency contour parameters, Fourier descriptors, and raw data. The experimental results demonstrate superior accuracy and robustness of the proposed method to classify dolphin whistles into distinct call types. The method can be generalized to all narrowband signals with time varying spectra.
Application of shear wave imaging and shear wave dispersion ultrasound vibrometry in assessing viscoelastic properties of human thyroid: In vivo pilot study
Authors: Mehrmohammadi Mohammad , Song Pengfei , Carrascal Carolina A. , Urban Matthew W. , Callstrom Matthew R. , Morris John C. , Chen Shigao , Greenleaf James F. , Fatemi Mostafa , Alizad Azra
Published: November 2013

Thyroid cancer is the fastest growing age and gender adjusted cancer in 2011 according the American Cancer Society. The majority of the clinically diagnosed thyroid nodules are benign while less than 5% represent intrathyroidal cancers. Currently, the clinical gold-standard procedure for assessing the thyroid nodules is needle biopsy, a procedure that is associated with significant financial burden as well as pain and risk for patients. Therefore, a noninvasive, affordable, and potentially widely available method to differentiate between benign and malignant thyroid nodules can play an important role in reducing the number of unnecessary biopsies. In this study, we investigate the feasibility of two acoustic radiation force elastography techniques, shear wave dispersion ultrasound vibrometry (SDUV) and comb-push ultrasound shear wave elastography (CUSE imaging), in identifying thyroid nodules (imaging) and differentiating between benign and malignant pathologies based on their elasticity and viscosity (SDUV measurements). Our preliminary results show that the measured shear elasticity and shear viscosity parameters depend on tissue type; hence, these measurements may be utilized to differentiate between healthy normal thyroid tissue, benign nodules, and malignant nodules. Further studies on a large population of patients is required to better evaluate the role of the combination of elasticity and viscosity properties of tissue in differentiating various thyroid nodules.
Historical perspective on R. Bruce Lindsay, A. O. Williams, R. T. Beyer, and P. J. Westervelt: Connections and branches surrounding the Brown era
Authors: Korman Murray S.
Published: November 2013

Starting from a timeline when R(obert) Bruce Lindsay graduated from Brown (1920), there is a lineage of so-called great-grandfather, grandfather, and father advisors leading up to his own research, and branches connecting new Ph.D.’s. His Ph.D. on the atomic models of the alkali metals began in Copenhagen, Denmark, under Niels Bohr and H.A. Kramers in 1922, and was completed at M.I.T. in 1924. Bruce Lindsay returned to Brown University in 1930 (from Yale), became chair in 1934 and Hazard professor in 1936. His interests in atomic physics switched to acoustics during and after WWII, obtained strong support from ONR and kindled a legendary relationship with the ASA, including 20 years as Editor-in Chief, and a gold medal. He brought on board Art Williams (1940), Robert Beyer (1945), and Peter Westervelt (1951). They also received medals. R.T. Beyer’s advisor at Cornell, Harry Sack, was a former student of Peter Debye. A.O. William’s and P. J. Westervelt’s advisors were Bruce Lindsay and Richard Bolt (M.I.T.), respectively. This poster presentation will also include threading together acoustics at Brown in an era including Jordan Markham, Bob Morse, Rohn Truell, Bruce Chick, Wes Nyborg, Charles Elbaum, and Humphrey Maris.
Percy Wilson, acoustical consultant
Authors: Wilson Geoffrey L.
Published: November 2013

Percy Wilson was Technical Adviser to The Gramophone magazine in England from 1925 to 1938. He wrote a monthly column called Technical Talk and also wrote articles for the Wireless Magazine. He was very well known in the UK Audio industry. He was a senior civil servant at the Board of Education and in 1937 was appointed Assistant Secretary of the Ministry of Transport, in administrative charge of the trunk roads division. Because of pressures of work due to the probable imminence of war with Germany, he was forced to give up most of his outside activities, but was able to resume them after the end of WW2 and his subsequent retirement from the Civil Service. He was Technical Editor of The Gramophone for many more years, and was active in the Audio Engineering Society, being one of the founders of the British Section. As the self-appointed family historian I will endeavor to present highlights of his life from the time of his birth in Halifax, Yorkshire on March 3, 1893, to his demise in Oxford on April 30, 1977, focusing primarily on his technical work.
Genealogy of Kenneth N. Stevens and the Speech Communication Group at the Massachusetts Institute of Technology
Authors: Hanson Helen , Shattuck-Hufnagel Stefanie
Published: November 2013

Ken often told a story to his advisees, illustrating how a seemingly insignificant event could change the course of a life. When Ken began his graduate studies at MIT, Leo Beranek learned that he had taken an acoustics class as an undergraduate and recruited him as a teaching assistant. Beranek was doing research on speech acoustics, and soon Ken was one of his research assistants. Thus, Ken’s decision to take an undergraduate acoustics course led him to his lifetime of work in speech communication, in which he found boundless pleasure. After completing his Sc.D. in 1952, Ken joined the MIT Faculty. His first doctoral student was James Flanagan. He supervised at least 31 more doctoral students and scores of post-doctoral, masters, undergraduate, and visiting students over 53 years. Ken collaborated with MIT colleagues (e.g., Morris Halle and Jay Keyser, Linguistics Dept.) and many researchers well beyond 77 Massachusetts Ave (e.g., Gunnar Fant, KTH, Sweden). His interest in how the physics of the vocal tract interacts with contrastive phonological categories unequivocally changed the field of Speech Communication, as well as the lives of his many students and collaborators who have gone on to establish their own laboratories and research programs.
Effect of the transient fluid-structure interaction on sound radiation from a partially submerged cylindrical pile
Authors: Hastings Mardi C.
Published: November 2013

A time-domain structural acoustics model of a partially submerged cylindrical pile excited by an impact force has been developed to predict underwater sound radiation for arbitrary field conditions. Radial boundary conditions are formulated using the velocity potential so pressure waveforms near the pile wall can be estimated; however, the rapid decay observed in measured waveforms is not easily predicted because radiation loading on the structure is also transient. The sudden acceleration of the wall initially results in a net flow of energy from the structure into surrounding fluids. Subsequently part of this energy radiates to the far field as a compressional wave; however, as the forced wall motion decreases and the spatial pressure gradient at the wall reverses direction, fluid accelerates back to the pile and re-excites the wall. A model for this transient fluid-structure interaction was formulated and integrated into the time-domain structural acoustics numerical model. By accounting for energy flow back into the structure, predicted pressure waveforms are in good agreement with field data. Results indicate that a significant portion of the kinetic energy remains in the near field and does not radiate sound, and that temporal characteristics of the impact force may influence far field sound radiation.
A model for underwater sound levels generated by marine impact pile driving
Authors: MacGillivray Alexander O.
Published: November 2013

Marine impact pile driving generates very high underwater sound pressures that can be harmful to aquatic life. Environmental assessments for pile driving projects typically require advance estimates of acoustic impact zones for marine mammals and fish. A computer model has been developed to predict the radiated acoustic field from impact driving of cylindrical piles. The stress wave in the pile is predicted using a force-generator model of the hammer-pile system. The force-generator model is coupled to a 1-D finite-difference model of longitudinal stress waves in a cylindrical pile. The radiated pressure is computed by matching the velocity boundary condition at the pile wall using a superposition of monopole sources distributed over the length of the pile in a layered 2-D fluid medium. The transfer function for the monopoles is computed using the near-field Hankel transform for radial particle velocity at the pile wall. Standard ocean acoustic modeling techniques are used to compute the Mach wave propagating away from the pile. As an example, predictions of the model are compared to field measurements obtained in a riverine environment.
Properties influencing the transmission loss and mitigation of the underwater sound from marine pile driving
Authors: Dahl Peter H.
Published: November 2013

The transmission loss of underwater sound generated by impact or vibratory pile driving, combined with the potential mitigation of this sound, ultimately determine the regulatory zone-of-impact on marine life. For impact pile driving the pile source assumes properties of a “phased array” as shown in Reinhall and Dahl [J. Acoust. Soc. Am. 130, 1209–1216 (2011)], where sound radiation arises from the state of radial expansion which travels down the pile at a speed which is supersonic relative to the speed of sound in water. The acoustic field that develops is shown to be the dominant contributor to peak underwater sound pressure. An important range scale can be identified that is useful for both guiding measurements, and for transmission loss modeling. For vibratory pile driving, measurements made at close range (within about a one water depth) show considerable low-frequency content that can be below the cut-off frequency of the waveguide. Some key properties of impact and vibratory pile driving will be discussed that govern the nature of transmission loss from, and influence mitigation strategies for, these sound sources. These properties are based on measurements made at marine construction sites in Puget Sound, Washington.
A negative stiffness metamaterial inclusion via small-scale curved structural elements
Authors: Klatt Timothy , Haberman Michael R.
Published: November 2013

This work presents a means to produce negative stiffness metamaterial units without employing inherent nonlinear material behavior or dynamic effects, but rather through large deformations of tailored microscale geometry. Specifically, the work of Qiu et al. [J. Microelectromech. Syst. 13, 137–146 (2004)] is generalized to create metamaterial units displaying non-monotonic stress-strain relationships with regions of negative stiffness behavior. These cells are designed to be embedded into a continuous matrix material and negative stiffness is elicited through pre-strain of the metamaterial unit cells brought about by changes in ambient pressure. This work presents a nonlinear hierarchical multiscale material model to estimate the macroscopic stiffness and loss of a composite material containing these pre-strained microscale structured inclusions. The multiscale model consists of two scale transition models: (i) an energy-based nonlinear finite element (FE) method to determine the anisotropic tangent moduli of the inclusion, and (ii) an analytical micromechanical model to determine the effective stiffness and loss tensors due to small perturbations about the local strain state of the metamaterial inclusions. Models and results for various volume fractions are presented and discussed.
Sound attenuation in ducts using locally resonant periodic flush mounted flexible silicon aerogel patches
Authors: Farooqui Maaz , Akl Wael , Elnady Tamer
Published: November 2013

In recent years, low frequency noise has become an important factor especially in the Aircraft, HVAC, and Automotive industries. In order to reduce this low frequency noise, noise attenuation by the classical Helmholtz resonators has size limitations due to the large wavelengths. Promising noise reductions, with flush mounted Silicon Aerogel patches, can be obtained implementing attenuation due to local resonance and that too without any size constraints. The objective of the current paper is to introduce locally resonant Silicon Aerogel patches flush mounted to an acoustic duct walls aiming at creating frequency stop bands at the low frequency zone (below 500 Hz). Green’s Function is used under the framework of interface response theory to predict the degree of attenuation of the local resonant patches. Realistic techniques for expanding the stop bandwidth have been introduced and difference between the Bragg scattering and the locally resonant mechanism was demonstrated using mathematical models. The effect of the arrays of patches on the effective dynamic density and bulk modulus has also been investigated. It is also shown that the numbers and periodicity of these local resonators also plays role in determining the depth and width of the acoustic band gap.
Uncertainty bounds estimation when simulating vibration response under aeroacoustic loading
Authors: Bremner Paul
Published: November 2013

The simulation of linear vibration response under aeroacoustic loading, involves the aeroacoustic loading spectrum and its spatial distribution, and the modal dynamics of the loaded structure. In most practical applications, this problem can only be addressed statistically because the aeroacoustic loading is temporally random and only partially space-correlated, requiring a time-averaged and space-averaged cross-spectrum description of both the loading and the structure vibration response. However, it is equally common that the spectrum and spatial correlation of the loading is uncertain and—particularly at higher frequencies or higher modal densities—even the modal dynamics of the structure are uncertain (e.g., due to uncertainties in the as-built boundary conditions). This paper will explore what is required to predict the statistical variance and the maximum expected vibration response—in addition to the space-time average cross spectrum—given uncertainty in the modeling parameters.
Modification of the spectral response of a pipe resonator using a subordinate array of coupled Helmholtz resonators
Authors: Glean Aldo A. , Vignola Joseph F. , Judge John A. , Ryan Teresa J.
Published: November 2013

The dynamic response of a resonant system can be manipulated by attaching a set of substantially smaller resonators with a prescribed distribution of properties. These smaller resonators are collectively referred to as a subordinate array. This work describes an experimental demonstration of such a manipulation, in which we alter one resonant peak of the primary system to create a flat bandpass response, while leaving the other resonances unaffected. In this instance, the primary resonant system is a pipe with one end closed and the other open, and the subordinate array consists of a set of small Helmholtz resonators. We demonstrate the desired modification of the system response at the third resonant frequency without significant change in adjacent resonances. Specifically, a single system resonance of the primary resonator shows a peak response when no subordinates are attached and exhibits a band pass response when the subordinates are attached. Sensitivity of system response to errors in design parameters is discussed and experimental results are compared to theoretical predictions.
Acoustic cue weighting across modalities in a non-native sound contrast
Authors: Schertz Jessamyn L. , Lotto Andrew J. , Warner Natasha , Cho Taehong
Published: November 2013

This work investigates the production and perception of the English stop voicing contrast on multiple acoustic dimensions by native speakers of Seoul Korean. Subjects completed a production task as well as a forced-choice identification task on stimuli varying on three acoustic dimensions (aspiration duration, pitch, and closure duration) in both English and Korean. On average, native Korean listeners relied more on pitch than on aspiration duration to categorize the English stop voicing contrast (which native English listeners distinguish primarily by aspiration). However, individual categorization patterns differed considerably, with some listeners using only pitch, some using only aspiration, and most using both. In contrast, in production, aspiration duration was a better predictor of voicing category than pitch, although pitch was still a stronger predictor than previously found in native English productions. The heavier reliance on pitch by Korean listeners may be attributable to the greater importance of pitch in their native stop contrast; however, there does not appear to be a consistent, straightforward mapping of English sounds onto the Korean categories. Results will be discussed in the terms of the perception-production interface on the level of individual acoustic cues, as well as the influence of native language cue weights on non-native sound contrasts.
Time-reversal-based underwater acoustic communication
Authors: Song Hee-Chun
Published: November 2013

Time reversal (TR) exploits spatial diversity to achieve spatial and temporal focusing in complex environments. Over the last decade its concept has been applied successfully to underwater acoustic communications in time-varying multipath environments with robustness and computational simplicity, as an alternative to conventional adaptive multichannel equalization. Temporal focusing (pulse compression) mitigates the intersymbol interference (ISI) and subsequent channel equalization removes the residual ISI, thus providing nearly optimal performance in theory. The spatial focusing capability facilitates multi-user communications without an explicit use of time, frequency, or code division, while an adaptive time reversal approach can further reduce the crosstalk among users. TR communications can be easily extended to time-varying channels using a block-based approach with periodic channel updates. This talk will present an overview of TR communications and recent advances including bidirectional equalization, single- versus multi-carrier approach, and communications with autonomous vehicles such as an AUV or Glider.
Impact of fine-scale sound-speed fluctuations on acoustic autocorrelation times in the East China Sea
Authors: Mignerey Peter C. , Turgut Altan
Published: November 2013

Autocorrelation times of acoustic signals propagating through shallow oceans are largely driven by sound-speed fluctuations. In August 2008, the Transverse Acoustic Variability Experiment obtained measurements in the East China Sea (65–80 m water depth) of fluctuating signals propagating 33 km from a moored source to a bottomed line array. Supporting environmental measurements were obtained by a towed conductivity-temperature-depth chain. For time periods without large nonlinear internal waves, the measured internal-wave power spectrum shows excess energy at high wavenumbers in comparison with the shallow-water internal-wave model of Levine. Likewise the associated sound-speed fluctuation spectrum exhibits high-wavenumber components in excess of a simple power law. Autocorrelation times of measured 300 Hz acoustic signals were compared with simulated times obtained using a parabolic-equation model to propagate acoustic fields through sound-speed fluctuations driven by linear internal-wave displacements. Results of the comparison are that median measured autocorrelation times (115 s) are shorter than simulations (300 s) driven by spectra with depleted high-wavenumber components. Simple frozen ocean simulations that translate the environment at 0.6 m/s produce autocorrelation times close to the data. [Work supported by the Office of Naval Research.]
Propagation of broad-band signals in shallow water in the presence of horizontal stratification
Authors: Katsnelson Boris , Malykhin Andrey , Tckhoidze Alexander
Published: November 2013

Horizontal stratification in shelf zone of the ocean is provided by existence of coastal wedge, temperature fronts, nonlinear internal waves, slopes, and canyons, where typical scales are up to tenths of kilometer in range and up to tenths minutes in time, for some perturbations spatial scales are essentially different in different directions in horizontal plane. In this case, there is remarkable horizontal refraction in sound propagation and frequency dependence of horizontal ray trajectories. It means that Fourier components of wideband signal propagate along different paths joining source and receiver in the horizontal plane. Distribution of spectral components in horizontal plane has crescent-like shape and restricted by rays, corresponding to boundary frequencies in spectrum. Propagating wide-band signal has additional spectral distortion as a result of different phase shift for spectral components, propagating along different paths. Also there is difference in directions of wave vectors for difference spectral components (tangents to horizontal rays), leading to phenomena similar to spatial dispersion: different directions of phase and group velocities, compression and decompression of pulses, additional time delay of signal, etc. Mentioned phenomena are considered for models of coastal wedge and temperature fronts. Analytical estimations are presented, as well as results of numerical modeling.
New healthcare safety risk assessment toolkit includes acoustics and noise control design measures for error prevention in medication safety zones
Authors: Kachur Mandy , Quan Xiaobo , Horan Daniel M. , Sykes David M.
Published: November 2013

The Facilities Guidelines Institute (FGI) manages the Guidelines for Design and Construction of Hospitals and Outpatient Facilities, which is used by the Joint Commission, many federal agencies, and authorities having jurisdiction in 42 states. The forthcoming 2014 edition calls for completion of a Safety Risk Assessment (SRA) to guide healthcare facility planning and design teams through systematic evaluation of safety issues in the built environment. In 2012, FGI and the federal Agency for Healthcare Research and Quality commissioned The Center for Health Design to oversee a three year effort to develop, test, and disseminate an SRA toolkit. The toolkit will consist of an online facility design questionnaire, supporting whitepapers and guidelines, and education for the healthcare community. The Acoustics Research Council was invited to contribute by integrating noise control language into the medication safety segment of the online questionnaire tool. The result is a question that specifically addresses acoustics and noise control design for error prevention in medication safety zones. In May 2013, the questionnaire content was finalized, and it will be validated, integrated, and evaluated during the subsequent two years. The co-authors are project participants.