bluuebunny/crossref_metadata_2025 huggingface dataset:
The research on the coverage area of multistatic sonar under various work modes
Authors: Sheng Xueli , Lu Jia , Dong Weijia , Yin Jingwei , Guo Longxiang , Wu Xiaochen
Published: May 2014

Absorption loss, which is an important characteristic in the field of underwater acoustic, caused by sea water is often neglected in the research on the coverage area of bistatic sonar. In this article, the coverage area of bistatic sonar considering absorption loss is studied. The change of coverage area caused by absorption loss and the approximation are discussed. When multistatic sonar works in different modes, detection criterion varies, and the coverage area cannot be simply considered as the union set or the intersection of coverage area of each bistatic sonar unit. The definition of multistatic coverage area is discussed, and the coverage area respect to the most relaxed criterion and the strictest criterion is studied.
Broadband incoherent virtual array beamforming on small scale array for passive detection
Authors: Dong Weijia , Sheng Xueli , Sun Chunyan , Lu Jia , Shen Hu
Published: May 2014

It cannot be guaranteed that array spacing corresponding to half-wavelength of each frequency during broadband signals passive detection process. Therefore, for high-frequency, side lobe will rise when array spacing is half the wavelength of the low-frequency. In addition, the main lobe of small-scale array will be wider due to limited array aperture. In order to resolve these two disadvantages for passive detection of small-scale array, virtual array beamforming based on time-delay information is studied in this paper. But this technology often requires high sampling frequency which will increase computational complexity. In order to use virtual array beamforming to processing broadband signals at lower sampling frequency, broadband incoherent virtual array technology based on phase information is introduced in this paper. The effectiveness of these two methods is shown by simulation and sea experiment.
Overview of the Target and Reverberation EXperiment 2013 (TREX13)
Authors: Tang Dajun , Hefner Brian T.
Published: May 2014

The Target and Reverberation Experiment (TREX13) is a shallow water reverberation experiment that endeavored to measure contemporaneously acoustic and adequate environmental data so detailed model/data comparison can be achieved and important environmental factors can be identified for different applications. TREX13 was sponsored by ONR Ocean Acoustics and the SERDP DoD programs. It was conducted during April to June of 2013 off the coast of Panama City, Florida, with participation from multiple institutions and involving three research vessels: The R/V Sharp and R/V Walton Smith from the United States, and the Canadian Force Auxiliary Vessel Quest. From a SONAR viewpoint, reverberation consists of two-way propagation and a single backscatter. Therefore, reverberation, transmission loss, and bottom backscatter were repeatedly measured over a time period of several weeks in the frequency band of 2–10 kHz, along with extensive environmental measurements. Discussed will be planning and execution of the field experiments, strategies and steps for data analysis, and modeling efforts.
Solving the inverse problem to extract ship radiated spectra in ocean environments
Authors: Knobles David P.
Published: May 2014

In ocean acoustics, one is often asked to find the Green's function G from the measured response R in R = GS, where S is the source spectrum. Experiments are often conducted where R is measured and S is known. However, the problem becomes more complicated when S is not known. The application of interest here is the solution for the source spectrum S = Inverse(G) R for a fast moving surface ship in uniform motion in an ocean environment where the propagation includes the interaction of sound with the seabed. What makes the solution possible is the multimodal nature of the propagation over a broadband of frequencies. As an application, the received spectra of merchant ships inside the Reliable Acoustic Path (RAP) range were recorded in the North Pacific Ocean on a vertical line array in an experiment called Church Opal in 1975. The effects of the seabed are clearly evident on the signals received on a hydrophone below the reciprocal depth. As a means of validation, the source spectra solutions of five merchant ships are compared to the spectra of similar ships recorded in other deep-water environments where the effects of the seabed are not present.
Development of a semi-analytical model for the underwater radiated noise from a driven pile—Comparison of the stationary phase approximation with exact integration for computing an inverse Fourier Transform of vertical wavenumber
Authors: Hall Marshall V.
Published: May 2014

A semi-analytical model is being developed for the noise radiated underwater when a cylindrical pile is struck axially by a hammer. The model is based on the coupled equations of motion for axial and radial vibration of a thin shell. It yields frequency-dependent axial phase velocity and attenuation (due to radiation) and produces a complete description of the shell vibration. For the purpose of describing the total radiated sound pressure, a harmonic solution is obtainable. The “Transform formulation of the pressure field of cylindrical radiators” by Junger and Feit is adopted. The result includes an inverse Fourier transform of a function of vertical wavenumber, and when the integrand is simplified using the stationary-phase approximation, the resulting pressure at short ranges is very large along a downward line in the range-depth plane. The slope of this line is that of the “Mach waves” described by Reinhall and Dahl, and the pressure is many times as great as that of the Mach waves. This approximation is therefore inapplicable. Results are also presented based on using wavenumber integration to compute the Fourier transform.
Statistical inference of seabed sound-speed structure in the Gulf of Oman Basin
Authors: Sagers Jason D. , Knobles David P.
Published: May 2014

Addressed is the statistical inference of the sound-speed depth profile of a thick soft seabed from broadband sound propagation data recorded in the Gulf of Oman Basin in 1977. The acoustic data are in the form of time series signals recorded on a sparse vertical line array and generated by explosive sources deployed along a 280 km track. The acoustic data offer a unique opportunity to study a deep-water bottom-limited thickly sedimented environment because of the large number of time series measurements, very low seabed attenuation, and auxiliary measurements. A maximum entropy method is employed to obtain a conditional posterior probability distribution (PPD) for the sound-speed ratio and the near-surface sound-speed gradient. The multiple data samples allow for a determination of the average error constraint value required to uniquely specify the PPD for each data sample. Two complicating features of the statistical inference study are addressed: (1) the need to develop a cost function that can both utilize the measured arrival structure and mitigate the effects of data errors and (2) the effect of small bathymetric slopes on the structure of the bottom interacting arrivals. [Work supported by ONR.]
Issues in estimating the seafloor scattering cross section with synthetic aperture sonar
Authors: Olson Derek R. , Lyons Anthony P.
Published: May 2014

The high resolution capabilities of synthetic aperture sonar (SAS) make it an attractive technology for estimating the seafloor scattering cross section. However, differences between traditional systems used for backscattering measurements, whose apertures span a few wavelengths, and synthetic arrays, whose apertures can span thousands of wavelengths, can violate the assumptions used in typical cross section estimation techniques. The issues introduced by very long synthetic arrays are caused by the integration of acoustic energy over a range of azimuth and grazing angles in the local coordinates of the resolved area on the seafloor. The resulting pixel intensity is not directly proportional to the scattering cross section, and methods other than solving the sonar equation are required. This research explores the effect of naively using SAS data to estimate the cross section and presents alternative estimation techniques.
Comparison between the Biot-Stoll model, the grain-shearing model, and the effective density fluid model with respect to sediments in the Yellow Sea
Authors: Noh Eunghwy , Lee Hunki , Kwon Oh-Cho , Ohm Won-Suk
Published: May 2014

There are some distinctive geophysical properties of sediments in the Yellow Sea, where mudflats are developed extensively. To select a physical model for acoustic wave propagation in the sediments is a critical issue in the analysis and the conceptual design of buried object scanning sonars. We consider three different sediment models to describe physical and geoacoustic properties of the sediments in the Yellow Sea: the Biot-Stoll model, the grain-shearing model, and the effective density fluid model (EDFM). These sediment models are evaluated in terms of their predictions of sediment properties compared with the measurement data. [This work was conducted in the Unmanned Technology Research Center (UTRC) sponsored by the Defense Acquisition Program Administration (DAPA) and the Agency for Defense Development (ADD) in the Republic of Korea.]
Laboratory measurements of high-frequency, broadband acoustic scattering of growing sea ice and oil beneath sea ice
Authors: Bassett Christopher , Lavery Andone C. , Maksym Ted
Published: May 2014

The morphology of sea ice during the early stages of growth is strongly dependent on environmental conditions. Under calm conditions, congelation ice forms through downward growth of ice crystals from the water surface. Under turbulent conditions (surface waves), rapid freezing of ice crystals occurs in the upper water column (frazil ice), eventually consolidating into pancake ice through repeated collisions and agglomeration of the loose frazil crystals. It is expected that high-frequency scattering from the basal layer of the ice varies for different sea ice types and can reveal structural information that governs the behavior of the ice and its interactions with the environment. Broadband scattering measurements of sea ice are presented beginning with ice-free conditions and through initial stages of growth in laboratory experiments for both congelation and frazil ice. With increased interest in drilling for hydrocarbon resources in the Arctic and the associated environmental concerns of an oil spill in ice-covered waters, improved methods for detection of crude oil both under or frozen within sea ice are needed. Acoustic scattering data are presented demonstrating how the scattering changes when crude oil is spilled beneath the ice.
A possibility to use respiratory noises for detecting diver and monitoring his physiologic status
Authors: Gorovoy Sergei , Korenbaum Vladimir , Tagiltcev Aleksandr , Kostiv Anatoly , Borodin Aleksey , Pochekutova Irina , Vasilistov Aleksey , Krupenkov Aleksandr , Vlasov Denis , Shiryaev Anton
Published: May 2014

The objective is acoustic detection of submerged diver and monitoring his physiologic condition. A possibility to use diver's own respiratory noises for this aim is analyzed. Respiratory noises were recorded above trachea of submerged scuba diver and in the water layer of shallow-water bay. Both signals contain quasi-periodic components induced by amplitude modulation of wideband respiratory noises with the rate of breathing maneuvers. These components are detected in water layer by means of energy processing of single hydrophone response (in a frequency band of 200–500 Hz) at the distances up to 50 m. The breathing rate is estimated by means of spectral transform of the signal envelope. It is well known that this index represents human individual physiologic status. Thus, it is pertinent for submerged diver's condition monitoring. The quasi-periodic components if detected may be used to estimate time delays in responses of several hydrophones, for example, by means of the signal envelopes correlation processing. These time delays are pertinent to find diver's location by triangulation technique.
On marine mammal acoustic detection performance bounds
Authors: Xian Yin , Nolte Loren
Published: May 2014

Most current research on marine mammal acoustic detection, classification, and localization does not consider optimizing detector algorithm performance for marine mammal vocalizations that have been propagated through an uncertain multipath environment. In this study, a Bayesian likelihood ratio approach, using the original time series data, is used to benchmark optimal detection performance (ROC's) for a known marine mammal source vocalization propagated through both a known and an example uncertain ocean environment. In addition, for these same ocean environments, the detection performance (ROC's) is obtained for several algorithms based on the spectrogram of the original data. Since the spectrogram does not preserve detailed phase information contained in the original data, any algorithm based on the spectrogram is not likely to be optimum for detection. The initial results show the additional detection performance gain possible over spectrogram based algorithms. Simulations and preliminary detection performance results (ROC's) are presented using a mathematical model from the literature of the North Atlantic Right Whale (NARW), along with numerical acoustic propagation software.
Simulation of underwater environments using the Discrete Huygens Modeling
Authors: de Carvalho Renato T. , Azevedo Gregário G. , Cordioli Júlio A.
Published: May 2014

The Discrete Huygens Modeling (DHM) is a numerical method that applies the Huygens principle to a discretized medium in order to provide time domain solutions to wave propagation problems. The method was originally conceived and applied in Electromagnetism, but previous works have shown that DHM is also a viable and promising approach for the simulation of acoustic problems. The main advantages of the method are its reduced computation cost when compared with other numerical methods and its relatively easy implementation and parallelization. However, little can be found in the literature about the use of DHM to underwater acoustic problems, and previous work have been limited to acoustic propagation only in the water column. In this work, a simple model of the acoustic field generated in the water column by a monopole was created, and the prediction of transmission, reflection, and scattering processes at the interface with the sediment were carried out. A DHM code has been fully implemented allowing the modeling of multiple media. The results obtained with the DHM model were compared with a Finite Element model yielding very good agreement, while the DHM approach proved to be much faster.
An equivalent physical model of three acoustic waves interaction in nonlinear medium
Authors: Yang Desen , Zhang Haoyang , Shi Shengguo , Jiang Wei , Shi Jie
Published: May 2014

Among the parametric effects, three waves interaction has been widely investigated in many fields of physics, such as nonlinear optics and plasma. The interaction of three acoustic waves in the medium with quadratic nonlinearity, which must satisfy conditions on their frequencies and wavenumbers, is essentially confined to energy exchange between three components. Based on Burgers equation, the propagation rules of three acoustic waves, which are called a resonant triad, are governed by a drastically simplified system of three coupled nonlinear ordinary differential equations. A mathematical equivalence between the equations for an acoustic triad and a simple parametric vibration system, the undamped elastic pendulum, is discussed in this paper by a multiple time-scale analysis. We study the dynamics of this system, drawing analogies between its behavior and that of the acoustic triad. Finally, it is certified that three acoustic waves interaction can be described by Mathieu type equations in case one acoustic wave is much stronger than the others in three waves. This means that experiments with an elastic pendulum can give us new insights into dynamics of mechanism in three acoustic waves interaction.
Theory and experiment of the resonance sound wave interactions in water
Authors: Yang Desen , Jiang Wei , Shi Shenguo , Zhang Haoyang , Jin Shiyuan
Published: May 2014

Equations governing nonlinear interactions among acoustic waves in water which satisfy the resonance conditions are derived from the Burgers equation. Taking into account of the second-order nonlinear, the three-wave interaction is the fundamental process of the interaction equations. Then, taking the three-wave interaction equation as an example, the energy transfer mechanism among the three acoustic waves is quantitatively analyzed. And the three-wave sound energy propagation is studied through numerical calculation. An interesting phenomenon is found that, when the three acoustic waves meet the relationship of a weak low-frequency sound and two strong high-frequency sounds, the energy of low-frequency sound will be amplified or reduced in some regions during the three-wave propagation. And the location and size of the regions are affected by the acoustic wave amplitude, frequency, and phase. The variation severities of low-frequency acoustic wave energy are mainly determined by other two high-frequency acoustic wave energy. The frequencies of two high-frequency sound waves have little effects on the energy of low-frequency sound wave. The region whether is amplification or reduction is determined by the phase difference of three waves. The variation laws of low-frequency sound energy are also verified by the experimental results in river.
Stochastic characterization of acoustic signals for sequential dispersion tracking and geoacoustic inversion
Authors: Aunsri Nattapol , Michalopoulou Zoi-Heleni
Published: May 2014

In previous work, we had shown how sequential Bayesian filtering methods can be used for the successful extraction of dispersion curves from broadband long-range acoustic data. Here, we extend this work by tracing carefully the true nature of the noise and the resulting probability density observations of the spectrogram of the received time series, employed in the tracking. The Gaussian model typically used in instantaneous frequency tracking relies on the assumption that noise is additive in the frequency domain. This model is, however, inaccurate. We discuss a chi-squared model of the acoustic data perturbations and its role in dispersion curve tracking. The new method provides much clearer curves than those computed with previous approaches. We demonstrate the potential of the technique by applying it to synthetic and real data for dispersion curve estimation and bathymetry and sediment sound speed inversion. [Work supported by ONR.]
Is low frequency sound level uniformly increasing on a global scale?
Authors: Miksis-Olds Jennifer L.
Published: May 2014

Deep water ambient sound level increases have been documented in the eastern North Pacific Ocean over the past 60 years. It remains unclear whether this increasing trend is observed in other regions of the world. In this work, data from the Comprehensive Nuclear Test Ban Treaty Organization International Monitoring System (CTBTO IMS) were used to examine the rate and direction of low frequency sound level change over the past decade in the Indian, South Atlantic, and Equatorial Pacific Oceans. The sources contributing to the overall sound level patterns differed between the regions. The dominant source observed in the South Atlantic was sound from seismic air gun surveys, while shipping and biologic sources contributed more to the acoustic environment at the Equatorial Pacific location. Unlike the increasing trend observed in the NE Pacific, sound levels over the past 5–6 years in the Equatorial Pacific were decreasing. Decreases were also observed for specific sound level parameters and frequency bands in the South Atlantic Ocean. Based on these observations, it does not appear that low frequency sound levels are increasing in all regions of the worlds' oceans. [Work supported by the Office of Naval Research.]
Advances in remote inference of physical and biological parameters using acoustic scattering techniques: Mapping the ocean in broadband “color”
Authors: Lavery Andone C.
Published: May 2014

Active narrowband acoustic scattering techniques have been used for decades to infer the distribution of marine organisms, such as fish and zooplankton, and to image physical processes, such as bubbles, suspended sediments, internal waves, and microstructure. Accurately inferring relevant biological and physical parameters from the acoustic returns, such as size or abundance of organisms or intensity of mixing, has represented a far more formidable obstacle, requiring a multi-faceted approach in order to make significant headway. Over the years, advances have been made in understanding the fundamental scattering physics, resulting in more robust and accurate scattering models. These models have been guided and tested by controlled laboratory scattering experiments as well as in a plethora of field experiments. Rapid advances in instrumentation and deployment platforms have also enabled new insights to be gained. In this presentation, a brief overview of this research area is given, results from the development and implementation of broadband scattering techniques for studying physical and biological processes over relevant spatial and temporal scales are presented, and limitations of these techniques considered. Possible future directions and advances in the area of remote physical and biological parameter estimation from active acoustic scattering data will be discussed.
Ambient pressure estimation using subharmonic emissions from contrast microbubbles
Authors: Kumar Krishna N. , Paul Shirshendu , Sarkar Kausik
Published: May 2014

In cancerous tumors, the interstitial fluid pressure is higher than that in normal tissues, and therefore can be used as a diagnostic marker. Here we are presenting the results of an in vitro study aimed at developing an ultrasound-aided noninvasive pressure estimation technique using contrast agents—Definity®, a lipid coated microbubble, and an experimental poly lactic acid (PLA) microbubbles. Scattered responses from these bubbles have been measured in vitro as a function of ambient pressure using a 3.5 MHz acoustic excitation of varying amplitude. Definity bubbles produced stronger subharmonic than the PLA coated ones, and therefore, are better suited for this application. At an acoustic pressure of 500 kPa, Definity® microbubbles showed a linear decrease in subharmonic signal with increasing ambient pressure, registering a 12 dB reduction at an overpressure of 120 mm Hg. However, at other frequencies, the variation of subharmonic emission with ambient pressure is nonmonotomic as was also predicted by theoretical modeling in our group. [Partially supported by National Science Foundation.]
Nonlinear intravascular ultrasound contrast imaging with a modified clinical system
Authors: Shekhar Himanshu , Awuor Ivy , Hashemgeloogerdi Sahar , Doyley Marvin M.
Published: May 2014

An intravascular ultrasound system capable of visualizing microbubble contrast agents could provide functional information for assessing atherosclerotic plaques. The goal of this study was to investigate the feasibility of contrast-enhanced imaging with a modified commercial intravascular ultrasound system. We employed an iLab™ system (Boston Scientific/Scimed, Natick, MA) equipped with an Atlantis™ PV imaging catheter (15-MHz center frequency, 26% fractional bandwidth) to image tissue mimicking phantoms that had contrast agent (Targestar-P®, Targeson Inc., CA) flowing in side channels parallel to the center lumen. Chirp-coded pulses were employed with transmit frequency of 12 MHz and peak pressures ranging from 1–2 MPa. The ultraharmonic response (18 MHz) was isolated from the backscattered radio-frequency using pulse inversion and matched filtering, to produce contrast specific images. We evaluated the detection sensitivity of the agent as a function of microbubble concentration and transmit pulse parameters. The results revealed that side channels with diameters ranging from 500 μm to 2 mm could be visualized for a wide range of concentrations. These results demonstrate that functional imaging of plaque neovascularization is feasible with commercially available intravascular catheters. Further development of such systems can facilitate the widespread use of contrast-enhanced intravascular ultrasound for preclinical research and clinical imaging.
Frequency-sum passive cavitation imaging
Authors: Haworth Kevin J. , Radhakrishnan Kirthi , Mast T. Douglas
Published: May 2014

Passive cavitation imaging (PCI) is a method for spatially mapping acoustic emissions caused by microbubble activity, including subharmonic and ultraharmonic emissions that denote stable cavitation. The point spread function (PSF) of passive cavitation images is diffraction limited. When typical clinical diagnostic linear arrays are used for PCI, the diffraction limit results in high azimuthal resolution but low axial resolution. Abadi et al. (2013)recently demonstrated a method called frequency-sum beamforming, which employs second-order or higher products of the acoustic emissions to manufacture higher frequencies, thereby reducing the size of the PSF. We applied this approach to cavitation emissions recorded from albumin-shelled bubbles insonified by 2 MHz ultrasound. Cavitation emissions were recorded on a 5 MHz, 128 element linear array using a Vantage scanner (Verasonics Inc.). Quadratic and fourth-order frequency-sum beamforming was applied to both harmonic and ultraharmonic cavitation emissions. Corresponding simulations were also performed to illustrate frequency-sum passive cavitation imaging of multiple bubbles. In comparison to delay-and-sum PCI, apparent areas of cavitation activity decreased when products of the emissions were used to perform frequency-sum beamforming. However, frequency-sum beamforming also produced artifacts, including the appearance of spurious emission sources.
Estimation of damping coefficient based on the impulse response of echogenic liposomes
Authors: Raymond Jason L. , Luan Ying , van Rooij Tom , Huang Shao-Ling , McPherson David D. , de Jong Nico , Holland Christy K.
Published: May 2014

Echogenic liposomes (ELIP) are under development as theragnostic ultrasound contrast agents for the diagnosis and treatment of cardiovascular disease. ELIP formulations have a phospholipid bilayer shell and are echogenic due to the presence of air; however, the exact location of the entrapped air has not been fully ascertained. Air pockets could either be stabilized by lipid monolayers within the liposome, or by the lipid bilayer shell. Our goal is to develop a more complete understanding of the encapsulation and shell properties of ELIP. This study demonstrates a method to estimate the damping coefficient using experimentally measured radius-time curves of the impulse response of individual ELIP using optical methods. The non-dimensional damping coefficient and the natural frequency of oscillation were estimated based on 140 individual impulse responses as measured with the Brandaris 128 fast-framing camera (15 Mfps) at 37°C. The damping coefficient was in agreement with the damping coefficient as measured previously using a broadband acoustic technique [Raymond et al., Ultrasound Med Biol. 40(2), 410–421 (2014)]. However, the natural frequency of oscillation was lower than previously reported.
The stable nonlinear acoustic response of free-floating lipid-coated microbubbles
Authors: Luan Ying , Renaud Guillaume , Kokhuis Tom , van der Steen Antonius , de Jong Nico
Published: May 2014

The stability of the microbubbles maintained by the lipid coating is crucial for diagnostic contrast-enhanced ultrasound imaging. We present a study of the stability of the dynamic response of single free-floating microbubbles (DSPC-based homemade microbubbles) with an acoustical camera. A 30 MHz probing wave (800 μs duration) measures the dynamic response of single microbubbles to 42 short sine bursts (1 MHz, 10 μs duration, 3 μs interval between each excitation) at three different peak pressures (25, 100, and 200 kPa). For each microbubble exposed to the 42 consecutive pulses, the following parameters were calculated: the radial strain at the driving frequency (ɛf), at the second/third harmonic frequencies (ɛ2f,ɛ3f), the ratio of radial excursion in expansion over that in compression (EoC) and the dc offset in the time-domain response. Nearly all 1500 individual microbubbles measured showed stable vibrational response. As expected ɛ2f and ɛ3f increase with ɛf, but they reach a plateau when ɛf exceeds about 30%. For ɛf smaller than 15%, we observed compression-dominant behaviors (dc offset < 0 and EoC < 1), while microbubbles show expansion-dominant responses (dc offset > 0 and EoC > 1) for ɛf larger than 15%.
Energy harvesting from acoustic fields
Authors: Cunefare Kenneth
Published: May 2014

While energy harvesting from a variety of ambient sources (vibration, light, and wind) has been demonstrated and sensing and communication applications to exploit those sources have been developed, acoustic energy as an ambient energy source has not received similar attention, except for a few very specialized special cases; this “hot topic” will focus on the special cases. The reason for otherwise limited development comes down to the basic physics of how much energy is available within a “typical” acoustic field. For airborne sounds, the energy density in sound fields that are perceived by humans to be loud to painfully loud (e.g., 80 to 140 dB, or ∼0.2 Pa to ∼200 Pa) actually represent an extremely low available energy source. In consequence, means must be taken to intensify an acoustic response, for example through resonance, but even so, the available energy remains limited. But, what if the sound field is not “typical”? One of the exceptions which enables viable acoustic energy harvesting is the sound field that exists inside of an operating jet aircraft engine. Another exception is within pumped and pressurized fluid systems, where acoustic pressure variations may reach into the mega-Pascal (MPa) range. Energy harvesting from such a fluid-borne acoustic source is feasible for powering sensors and wireless communication systems, has been successfully demonstrated, and may yield commercialized technology within only a few years.
The phenomenon of self-trapping of a strongly nonlinear wave
Authors: Rudenko Oleg , Hedberg Claes
Published: May 2014

Self means here an effect of a wave on itself. Several self-action phenomena are known in nonlinear wave physics. Among them are self-focusing of beams, self-compression of light pulses, self-channeling, self-reflection (or self-splitting) waves with shock fronts, self-induced transparency, and self-modulation. These phenomena are known for weakly nonlinear waves of different physical origin. Our presentation at ASA meeting in Montreal [POMA 19, 045080 (2013)] was devoted to strongly nonlinear waves having no transition to the linear limit at infinitesimally small amplitudes. Such waves can demonstrate particle-like properties. Self-trapping consists of the arrest of wave propagation and in the formation of a localized state. In particular, the model generalizing the Heisenberg' ordinary differential equation to spatially distributed systems predicts periodic oscillations but no traveling waves. Different models for strongly nonlinear waves will be considered and some unusual phenomena will be discussed. Preliminary results were published in Ac. Phys. 59, 584 (2013) and Physics-Uspekhi (Adv. Phys. Sci.) 183, 683 (2013). [This work was supported by the Megagrant No.11.G34.31.066 (Russia) and the KK Foundation (Sweden).]
Remotely monitoring performance in sports acoustically
Authors: Browning David , Scheifele Peter
Published: May 2014

In many sports, a coach will tell you that their trained ear can detect a superior performance. Volleyballs, soccerballs, and footballs all resonate at a characteristic frequency when struck. The resulting sound can be monitored off the field of play to determine how hard they were hit. A simple sound level meter can be easily modified to make a smackmeter. A bit more complicated but perhaps more rewarding is the resonate sound from aluminum baseball bats, or tennis and squash reckets, when can reveal not only how well but where the hit was made. Monitoring the sound of the stumming shaft of a golf club during a swing gives valuable information on swing speed and uniformity. Most every sport, for example, how about the splash of a dive, appears to have sounds that could be worthwhile to remotely monitor, especially given the resolution and speed of modern analysis techniques.
Pre-babbling infants prefer listening to infant speech: Implications for vocal learning in humans
Authors: Masapollo Matthew , Polka Linda , Ménard Lucie
Published: May 2014

For human infants to engage in vocal learning, they must effectively monitor and assess their own self-produced speech, which entails perceiving speech produced by an infant. Yet, little is known about how infants respond to infant-produced speech. Here, we demonstrate that pre-babbling infants prefer listening to infant speech. Across four experiments, 3-to-6-month-olds were tested in a preferential listening procedure, using vowels synthesized to emulate productions by female adults and infants. In experiment 1, infants listened longer to vowels produced by infant than adult speakers. However, in experiment 2, infants failed to show any listening preference for infant versus adult vowels synthesized with matching, infant-appropriate pitch values, suggesting that infants were either attracted to higher voice pitch per se or to infant-like voice pitch. Failing to support a bias of the first type, infants in experiment 3 showed no listening preference when presented infant vowels with higher and lower infant-appropriate pitch values. Moreover, in experiment 4, infants showed a preference for infant versus adult vowels when synthesized with pitch values that are appropriate for a female using adult-directed speech; this suggests that infants are also attracted to infant vocal resonance properties. The implications of these results for speech development are discussed.
Differences in the acoustic correlates of intonation in child and adult speech
Authors: Thorson Jill C. , Morgan James L.
Published: May 2014

During speech perception, toddlers use prosodic cues, such as pitch, in order to identify the most salient/prominent information in the discourse. This process is critical in facilitating early word recognition and learning. How do children then use these acoustic cues in their own speech in comparison to mature adult speech? The motivation for this study is to examine the acoustic correlates of intonation employed by child (mean: 2.5 years) and adult speakers of English during a guided spontaneous production task. During an interactive game, we elicit a set of target nouns and label them as one of three types: (1) new, uttered for the first time by the participant, (2) given, previously uttered at least once by the participant, or (3) contrastive, uttered in direct opposition to a previously mentioned referent. Along with labeling the pitch accent, we measured f0 range, f0 slope, duration, and intensity for each target word under these varying conditions. These measurements allow us to compare the types of pitch accents used by children and adults, and how each group employs the acoustic correlates of intonation. Identifying how these parameters are used during production is an important step in understanding speech development in early language acquisition.
Mothers do not enhance phonemic contrasts of Mandarin lexical tones in child-directed speech
Authors: Wong Puisan , Wang Xin , Xi Wenna , Li Lingzhi , Yu Xin
Published: May 2014

Child-directed speech is characterized by higher pitch, more expanded pitch contours, and more exaggerated phonetic contrasts, which was suggested to facilitate speech sound acquisition. This study examined the perceptual and acoustic differences of mothers' disyllabic Mandarin lexical tones directed to adults and children to determine whether mothers exaggerated the pitch targets of the four Mandarin tones when speaking to children. Twelve Mandarin-speaking mothers produced 700 child-directed (CD) and adult-directed (AD) disyllabic words in a picture naming task. Five Mandarin-native speakers identified the mothers' AD and CD tones in filtered speech. Overall, CD lexical tones were identified with significantly lower accuracy than AD lexical tones (89% vs. 94%, S = 25.5, p = 0.006, r = 0.927, Wilcoxon Signed Rank Test). Acoustic analysis showed that the mean fundamental frequency (f0) of the four tones in both syllables was significantly higher in CD than in AD productions. No difference was found between AD and CD in the distinctive pitch targets for the 4 tones, namely pitch shift for Tone1, F0 slope for Tone2, minimum F0 for Tone3 and F0 slope for Tone4. F0 plots showed mostly parallel contours in AD and CD productions without exaggeration of the phonetic contrasts of the tones. [Work supported by NIDCD F31 DC008470-01A1.]
Timecourse of word recognition for listener-oriented speaking style adaptations
Authors: van der Feest Suzanne V. , Smiljanic Rajka
Published: May 2014

Previous research has found that listener-oriented speaking style adaptations, such as Infant Directed Speech (IDS) and Clear Speech (CS), aid perception and development and improve intelligibility for children and adults, respectively. However, less is known about whether these different speaking styles enhance intelligibility in general, or if young children benefit most from IDS features aimed at capturing and maintaining attention. Additionally, information about time course differences in word recognition for these speech modifications has not been investigated. This study investigates both questions by presenting young adult listeners with semantically anomalous and meaningful sentences produced in IDS, CS, and Conversational (CO) Speech. Listeners participated in (1) a word-recognition-in-noise test and (2) a visual word recognition paradigm tracking eye movements. Results showed facilitated word recognition in noise for both IDS and CS compared to CO. Both speaking style adjustments also resulted in increased speed of word recognition in the visual paradigm. Semantic context provided additional facilitation only when more exaggerated acoustic cues were present (in IDS and CS). Preliminary analyses show that even for adult listeners IDS provided the greatest perceptual benefits, indicating that established advantages of IDS for young listeners cannot be mainly attributed to affect in addition to enhanced acoustic cues.
Acoustical Society of America R. Bruce Lindsay Award 2014: Matthew J. Goupell
Authors: Litovsky Ruth Y. , Hartmann William M.
Published: May 2014

The R. Bruce Lindsay Award (formerly the Biennial Award) is presented in the Spring to a member of the Society who is under 35 years of age on 1 January of the year of the Award and who, during a period of two or more years immediately preceding the award, has been active in the affairs of the Society and has contributed substantially, through published papers, to the advancement of theoretical or applied acoustics, or both. The award was presented biennially until 1986. It is now an annual award.
Acoustical Society of America Gold Medal 2014: Brian C. J. Moore
Authors: Oxenham Andrew J. , Carlyon Robert P.
Published: May 2014

The Gold Medal is presented in the spring to a member of the Society, without age limitation, for contributions to acoustics. The first Gold Medal was presented in 1954 on the occasion of the Society’s Twenty-Fifth Anniversary Celebration and biennially until 1981. It is now an annual award.
Noise prediction of vehicle sources on freeways and arterials using measured sound data
Authors: LoVerde John J. , Dong David W. , Rawlings Samantha
Published: May 2014

Evaluation and mitigation of noise from vehicular sources is common as a building design criterion and has been part of the California State Building Code and HUD multi-family building design requirements since the 1970s. It is now included in Green Building Design Standards and school and healthcare facility design guidelines and is expanding to all types of buildings with the addition of the new acoustics credit in LEED version 4. These criteria require that the noise level be quantified precisely, but do not provide a method for defining the noise level given the normal variations in noise level. This paper examines the factors that should be considered when defining the exterior noise from vehicular sources. Methods for predicting the noise level using data from relatively short measurement periods are evaluated, and minimum survey requirements to determine specific exterior noise parameters are suggested.
Concrete core activation and suspended ceilings: Designing for comfort, energy efficiency, and good acoustics
Authors: Vercammen Martijn , Peperkamp Hanneke
Published: May 2014

The trend to design energy-efficient buildings continues. Both legislation as sustainability assessment methods have increased the popularity of thermally activated concrete slabs. It is a way to use low temperature heating and high temperature cooling which makes it very suited for the use in low energy systems. The efficiency of these systems relate to the surface area, often the ceiling area. Exactly that surface was already the domain for the sound absorbing ceiling. So in new buildings with high energy performance due to concrete core activation, the sound absorption is often banned, resulting in very poor acoustics. The use of open, sound absorbing ceilings will have an influence on the thermal capacity of the concrete slabs, However, little is known about this effect. To investigate the effect of open ceilings to both the cooling capacity as the sound absorption, theoretical/empirical models have been made to estimate the effect on the cooling capacity and the sound absorption. The method is also tested in a field situation. It turns out that optimization is possible, with both cooling capacity as sound absorption around 70% of the maximum.
Acoustics testing and simulation analysis of waiting hall in the line-side high-speed railway station
Authors: Liu Gang , Hou Dan , Wang Lixiong , Dang Rui
Published: May 2014

Integrated the flow density changes of the waiting hall in a line-side high-speed railway station, an on-site measurement of noise environment is carried out. The characteristics of the acoustic environment are discussed in this study. Furthermore, combining the measured data of the background noise, acoustic computer simulation program ODEON calculates the reverberation time and speech transmission index of public broadcasting system. The results indicate that the reverberation time exceeds 5 s and the speech intelligibility of the south waiting room and dining area in second floor is lower than 0.4. Against the existing problems, various scenarios for upgrading the acoustic environment of waiting room are presented and proved to be efficient. Moreover, from the optimization process, it is certificated that the requirement of speech intelligibility can be also satisfied when appropriately relaxing the reverberation time limits specified in the regulation.
Acoustical considerations in design and construction of Turkish Contractors Association headquarters
Authors: Sü Gül Zühre , Caliskan Mehmet
Published: May 2014

A LEED candidate building of Turkish Contractors Association Headquarters is a prestige building located in Ankara, the project and construction of which is sponsored by leading contractor companies of Turkey. As it represents the status of Turkish construction industry, from concept phase to the very recent inauguration of the building, the major consideration has been the application of latest technology and concepts such as sustainability within the scheme of building that can pioneer future works in the field. Chilled beam ventilation is one example of new technologies applied in the building system design that takes into account high energy efficiency with minimum use of fuel or natural sources. In acoustical terms, the building envelope and structural members together with interior and environmental noise sources in relation to the building services are studied. In order to provide acoustical comfort levels in acoustically sensitive spaces and to control noise and vibration at the source and sound paths, materials and methods are developed. Specifically acoustical interventions and solutions proposed for multi-purpose hall, offices, board and meeting rooms, foyers, mechanical rooms, roof-top units, and generators located close by at the site are discussed within the context of this paper.
Detecting and locating manatees in a zero visibility environment
Authors: Rivera-Chavarria Mario R. , Guzman Hector , Castro Jorge
Published: May 2014

Manatees are an endangered species, and their population numbers have not been estimated in Panamian wetlands. Traditional monitoring methodologies using aerial surveys and visual sighting are ineffective for such turbid environments. We did a nine-month passive-acoustic survey using a Kayak with a stereo hydrophone array to detect and locate west Indian manatees in San San Pond Sak and Changuinola rivers in Panama. Twice a day transects with a total covering of 1700 km resulted 110 localizations and the recording of 1339 manatee vocalizations. Individual counting and the identification of biologically relevant sites is possible based on passive acoustics. Only a 2% of the acoustic detections were accompanied by clear sightings, indicating that visual census methodologies are ineffective in turbid environments and drastically underestimate manatee populations. We recommend this low-cost methodology to estimate manatee population more reliably in previously unsurveyed areas.
Fin whale song characteristics recorded on ocean bottom seismometers in the Northeast Pacific Ocean
Authors: Weirathmueller Michelle , Wilcock William S. D.
Published: May 2014

Fin whales produce low frequency sequences of vocalizations that can be detected opportunistically on ocean bottom seismometers (OBSs). Using an automatic detection algorithm, we have analyzed fin whale calls recorded on OBSs in the Northeast Pacific Ocean over broad spatial and temporal scales. The Cascadia Initiative experiment consists of 70 OBSs deployed for a total of four years (2011–2015). It extends from Vancouver Island to Cape Mendocino, and several hundred kilometers offshore. Additional OBS data that overlap spatially with the northern portion of the Cascadia Initiative instruments are available from the Neptune Canada cabled observatory, which has been online since 2009, and from standalone deployments between 2003 and 2006. With this study, we examine call characteristics and seasonal call counts for patterns that might indicate migratory movements or distinct acoustic populations. Both frequency and inter-pulse interval (IPI) are automatically extracted for each detected call and seasonal and inter-annual calling patterns are examined using daily binned call count histograms. Preliminary analysis of a subset of Cascadia Initiative data from 2011 to 2013 shows a dominant sequence of alternating classic and backbeat calls at center frequencies of 20 and 18.5 Hz, respectively, and preceding IPIs of 16 and 18 s, respectively.