bluuebunny/crossref_metadata_2025 huggingface dataset:
The acoustic environment of the Florida manatee: Correlation with level of habitat use
Authors: Miksis-Olds Jennifer L. , Miller James H. , Tyack Peter L.
Published: September 2013

The Florida manatee is regularly exposed to high volumes of vessel traffic and other human-related noise pollutants because of their coastal distribution. Quantifying specific aspects of the manatees’ acoustic environment will allow for a better understanding of how these animals are responding to both natural and human induced changes in their environment. Acoustic recordings and transmission loss measurements were made in two critical manatee habitats: seagrass beds and dredged basins. Twenty-four sampling sites were chosen based on the frequency of manatee presence in specific areas from 2000–2003. Recordings were composed of both ambient noise levels and transient noise sources. The Monterey-Miami Parabolic Equation Model (MMPE) was used to relate environmental parameters to transmission loss, and model outputs were verified by field tests at all sites. Preliminary results indicate that high-use grassbeds have higher levels of transmission loss compared to low-use sites. Additionally, high-use grassbeds have lower ambient noise in the early morning and later afternoon hours compared to low-use grassbeds. The application of noise measurements and model results can now be used to predict received levels, signal-to-noise ratios, and reliable detection of biologically relevant signals in manatee habitats and in the many different environments that marine mammals live.
Killer whale caller localization using a hydrophone array in an oceanarium pool
Authors: Bowles Ann E. , Greenlaw Charles F. , McGehee Duncan E. , Van Holliday D.
Published: September 2013

A system to localize calling killer whales was designed around a ten-hydrophone array in a pool at SeaWorld San Diego. The array consisted of nine ITC 8212 and one ITC 6050H hydrophones mounted in recessed 30×30 cm2 niches. Eight of the hydrophones were connected to a Compaq Armada E500 laptop computer through a National Instruments DAQ 6024E PCMCIA A/D data acquisition card and a BNC-2120 signal conditioner. The system was calibrated with a 139-dB, 4.5-kHz pinger. Acoustic data were collected during four 48–72 h recording sessions, simultaneously with video recorded from a four-camera array. Calling whales were localized by one of two methods, (1) at the hydrophone reporting the highest sound exposure level and (2) using custom-designed 3-D localization software based on time-of-arrival (ORCA). Complex reverberations in the niches and pool made locations based on time of arrival difficult to collect. Based on preliminary analysis of data from four sessions (400+ calls/session), the hydrophone reporting the highest level reliably attributed callers 51%–100% of the time. This represents a substantial improvement over attribution rates of 5%–15% obtained with single hydrophone recordings. [Funding provided by Hubbs-SeaWorld Research Institute and the Hubbs Society.]
Inertial cavitation dose produced ex vivo in rabbit ear arteries with optison
Authors: Tu Juan , Brayman Andrew , Matula Thomas
Published: September 2013

Ultrasound-induced inertial cavitation (IC) effects were studied ex vivo in rabbit ear arteries with the addition of ultrasound contrast agents (UCAs). Ears were removed from New Zealand white rabbits immediately after being euthanized under a protocol approved by the University of Washington IACUC. The auricular arteries were perfused with varying concentration of UCA (Optison) in saline and exposed to 1.155-MHz pulsed high-intensity focused ultrasound (HIFU) with constant PRF (10 Hz), pulse length (20 cycles), and total treatment time (20 s). Experiments were performed for variable peak negative acoustic pressure (P−) (from 0.19 to 3.31 Mpa) and Optison volume concentration (0% [saline only], 0.1%, 0.2%, 0.5%, and 1%). Cavitation activity was quantified by IC Dose (cumulated root-mean-squared [rms] broadband noise amplitude in a particular band in the frequency domain). The results showed that (1) IC activity was induced much more easily with the addition of Optison, even at low volume concentration, such as 0.1%. (2) IC dose increased significantly with the increasing acoustic pressure and Optison concentration. (3) Higher concentrations of Optison decreased the IC threshold. [Work supported by NIH 8RO1 EB00350-2.]
Signal-to-noise ratio and attenuation of Optison® microbubbles in blood as a function of imaging frequency
Authors: Zanetti Paolo , Coussios Constantin-C. , Roy Ronald A.
Published: September 2013

Using an active cavitation detector (ACD), the power backscattered by various concentrations of Optison® microbubbles (signal) was compared to the power backscattered by a 50% hematocrit suspension of red blood cells in saline (noise), as a function of imaging frequency (5–30 MHz). A theoretical model, based on direct experimental measurements of the size distribution of Optison® microbubbles, was developed to predict the signal-to-noise ratio (SNR) of microbubbles in blood, assuming no interactions between the populations of scatterers. The SNR was shown experimentally to decrease with increasing imaging frequency up to a point where Optison® no longer provided image enhancement. Measurements of the SNR were repeated in a suspension of 0.8% hematocrit, which has the same backscattering coefficient as a 50% hematocrit suspension. The SNR for Optison® in 50% hematocrit was found to be lower than for the 0.8% hematocrit suspension at all frequencies, suggesting that the large number density and close proximity of the red blood cells inhibits the acoustic response of the microbubbles. Measurements of sound attenuation through suspensions of red blood cells with or without Optison® were also obtained, indicating that the microbubbles barely contribute to the overall attenuation. [Work supported by the NSF and the ASA.]
Interaction between therapeutic ultrasound propagation and cavitation bubbles
Authors: Liebler Marko , Dreyer Thomas , Riedlinger Rainer
Published: September 2013

In medical applications of high intense focused ultrasound using pressure pulses or continuous wave signals, cavitation is considered to play a significant role for physical and biological effects. To further develop therapeutic applications it is essential to improve the understanding of these cavitation related effects. In this paper a numerical model is presented to simulate the interactions between ultrasonic waves and cavitation bubbles. The FDTD model is based on a two-phase continuum approach for bubbly liquids and combines nonlinear ultrasound propagation with cavitation bubble activity. Experimental and numerical investigations are presented demonstrating the influence of cavitation bubbles on ultrasound propagation. Measurements with a fiber optic hydrofone for pulsed piezoelectric transducers show significant variations in focal pressure waveforms after the first tensile phase of the wave for different gas content. It is supposed that these changes are caused by cavitation effects. Calculations with different bubble densities confirm these experimental results and demonstrate that the first positive pressure part of the wave is not affected by bubble activity. Increasing the gas content leads to a truncated tensile part followed by augmented pressure oscillations. Further on, simulation results for the evolution and impact of cavitation bubble clouds in CW applications are presented.
Design of multi-frequency cavitation fields for spatial control of cavitation
Authors: Sokka Sham D. , Gauthier Thomas P. , Hynynen Kullervo
Published: September 2013

Cavitation has been implicated as the primary mechanism for a whole host of emerging applications. In all these applications, the main concern is to induce cavitation in perfectly controlled locations in the field; this means specifically to be able to achieve cavitation threshold at the geometrical focus of the transducer without stimulating its near field. In this study, we develop multi-frequency methods to preferentially lower the cavitation threshold at the focus relative to the rest of the field. Three families of multi-frequency driving waveforms are evaluated in a bubble model incorporating rectified diffusion. The results from the optimal waveform analysis are verified by experiment. Finally, the performance of the rest of the acoustic field in suppressing cavitation when cavitation is induced at the focus is investigated theoretically and checked experimentally. This study shows that multi-frequency phased arrays could be used to precisely control cavitation. Cavitation threshold is proved to be almost 1.5 times higher in the near field than at the focus. The concept of cavitation field is introduced and complements cavitation studies concentrating on the focal behavior only.
Simulation of an acoustically excited bubble near a simulated ‘‘cell.’’
Authors: Gracewski Sheryl M. , Miao Hongyu , Dalecki Diane , Miller Morton W.
Published: September 2013

A variety of independent studies have reported increased bioeffects such as hemolysis and hemorrhage induced by high-intensity ultrasound when ultrasound contrast agents are present. Therefore, to better understand the role of cavitation, one-, two-, and three-dimensional models have been developed to investigate the interactions between ultrasonically excited bubbles and model ‘‘cells.’’ First, a simple one-dimensional model based on the Rayleigh–Plesset equation was used to estimate upper bounds for strain, strain rate, and areal expansion of a simulated red blood cell. Then, two- and three-dimensional boundary element models were developed (with DynaFlow Inc.) to obtain simulations of asymmetric bubble dynamics in the presence of rigid and deformable spheres. A spherical ‘‘cell’’ near an ultrasonically excited bubble was modeled using Tait’s equation of state for water, surrounded by a ‘‘membrane’’ with surface tension that increased linearly with areal expansion. The effect of a nearby ‘‘cell’’ on bubble response, the resulting pressure field around the ‘‘cell,’’ and ‘‘cell’’ membrane tensions were investigated. Preliminary results were compared with critical values for hemolysis reported in the literature. [Work supported by NIH.]
Model for interaction of bubbles in a cloud near a rigid surface
Authors: Zabolotskaya Evgenia A. , Ilinskii Yurii A. , Meegan G. Douglas , Hamilton Mark F.
Published: September 2013

Bubble clouds produced during lithotripsy undergo complicated motions including bubble interactions that may inhibit kidney stone comminution. Our study of bubble interactions is motivated by high-speed photographs reported by Pishchalnikov et al. [J. Acoust. Soc. Am. 114, 2386 (2003)]. In the work reported here, we simulated the observed bubble motion with a model based on the equations derived by Zabolotskaya [Sov. Phys. Acoust. 30, 365 (1984)]. The equations for interaction of two bubbles were generalized and solved numerically for a cluster of n bubbles near a rigid boundary, which represents the stone. The initial spatial distribution of bubbles in three dimensions was assumed to be random. When a short negative pressure pulse was applied, the simulated bubbles grew in size. When two bubbles touched each other, they were merged into a single bubble that conserved mass of the gas. Results are presented in selected planes intersecting the bubble cloud for different instants of time. Bubble interaction was found to reduce the maximum sizes to which the bubbles grow. The bubbles near the rigid boundary are constrained by neighboring bubbles and grow less rapidly, and to smaller sizes, than other bubbles. Interactions within the cloud thus suppress bubble growth and cavitation. [Work supported by ARL:UT IR&D.]
Volume measurements of the cell destruction zone and thermal decomposition zone in the focus of a shock wave transducer
Authors: Mastikhin Igor , Teslenko Vyacheslav , Nikolin Valery
Published: September 2013

Evaluation of the volume of the cell destruction zone is of interest in biomedical applications of shock waves (SW). The volume depends on mechanical properties of the cell membranes and is different for different cell types. In this work, we evaluated the cell destruction volume for two different cell types, tumor cells Crebs-2 and red blood cells. We used 0 70 0.5-s SW pulses with 45-MPa pressure in the focal zone. The concentration of destroyed cells was counted by dyeing in the case of tumor cells, and by spectrometry of released hemoglobin in the case of RBC. The cell destruction volume was calculated from destruction versus pulse number data and measured as 0.0135 ml for tumor cells. For RBC, the volume was 0.021 ml. To evaluate the effective volume of thermal zone, we used EPR signal of stable disulphide biradicals. Under SW action, S–S bonds of the biradicals rupture. The volume measurements were 0.003 ml. Since for that biradical, S–S bonds rupture at temperatures >80°C, and concentration of free radicals was an order lower (measured by spin traps) than of the produced monoradical, the rupture was caused by thermal decomposition. Thermal effects can play a significant role in SW action.
Pitch bending on the cornet
Authors: Campbell D. Murray
Published: September 2013

A successful model of a brass wind instrument must be able to describe the playing technique known as ‘‘lipping,’’ in which the player can bend the pitch of a note by modifying the setting and tension of the lips. This technique is of special importance on the lip-reed instrument known as the cornet or cornetto, which was important in the 15th and 16th centuries but fell out of use by the end of the 18th century. The instrument consists of a short wooden tube of approximately conical bore with seven side holes. Chromatic notes must be obtained by cross fingering, and good intonation requires fine control of the lipping technique. Recent experimental studies of lipping on the cornet are described, and implications for modeling of the lip reed are discussed.
Acoustics of old Asian bells
Authors: Rossing Thomas D.
Published: September 2013

The art of casting bronze bells developed to a high level of sophistication in China during the Shang dynasty (1766–1123 BC). Many chimes of two-tone bells remain from the Western and Eastern Zhou dynasties (1122–249 BC). With the spread of Buddhism from the third century, large round temple bells developed in China and later in Korea, Japan, and other Asian countries. Vibrational modes of some of these bells have been studied by means of holographic interferometry and experimental modal testing. Their musical as well as acoustical properties are discussed.
The acoustics of carved Baltic psaltery
Authors: Peekna Andres , Rossing Thomas
Published: September 2013

The Baltic psaltery family of plucked string instruments includes the kantele (Finland), the kannel (Estonia), the kokle (Latvia), the kankles (Lithuania), and the wing-shaped gusli (Northwestern Russia). In its archaic, carved form, it has a limited range, 5–13 strings, usually tuned diatonically. By means of electronic TV holography, we studied the modes of vibration of several psalteries based on historic instruments. On the better instruments, the main body resonances are well distributed in frequency so that they support the various strings. Good string-to-soundbox coupling also appears to play a role. A useful method for studying string-to-soundbox coupling involves scanning at intervals as low as 0.1 Hz for narrow peaks within the nominal tuning range of the strings, and comparing them to their neighboring body resonances, while using electronic TV holography. Predictions of the Helmholtz resonance from sound-hole dimensions and air-cavity volume while neglecting damping in the sound holes yield upper limits when many small sound holes are involved. The locations of the sound holes, as well as their area, are found to have significant effects on sound quality and volume.
The acoustics of the Bagana
Authors: Weisser Stephanie , Demolin Didier
Published: September 2013

The Bagana lyre of Ethiopia is an instrument with a very particular timbre whose acoustic characteristics is determined by U-like leather strips placed between each string and the bridge. These leather strips give a deep buzzing sound that influences pitch duration, intenisty, and timbre. The sounds of the instruments were recorded with and without buzzers for comparison. Data were analyzed to characterize the main acoustic features of the instrument. In addition a high-speed camera (400 images/second) was used to describe the different vibratory modes. The main observation is that buzzers enhance the spectrum up to more than 10 kHz; they also modify the attack and the release of the sound. The duration and the loudness of the sound are increased because they enhance the energy’s repartition in the spectrum, especially in the area around 1500–300 Hz. Another effect of the buzzers is that the instrument produces low pitch and loud sounds without having a big resonator or tall harmonic strings.
Acoustics of glass harmonicas
Authors: Rossing Thomas D.
Published: September 2013

Glass musical instruments are probably as old as glassmaking. At least as early as the 17th century it was discovered that wine glasses, when rubbed with a wet finger, produced a musical tone. A collection of glasses played in this manner is called a glass harp. Another type of glass harmonica, called the armonica by its inventor Benjamin Franklin, employs glass bowls or cups turned by a horizontal axle, so the performer need only touch the rim of the bowls as they rotate to set them into vibration. We discuss the modes of vibration of both types of glass harmonica, and describe the different sounds that are emitted by rubbing, tapping, or bowing them. Rubbing with a wet finger tends to excite only the (2,0) mode and its harmonics through a ‘‘stick-slip’’ process, while tapping excites the other modes as well.
Noise pollution: A threat to our mental and physical well-being
Authors: Bronzaft Arline L.
Published: September 2013

While noise may not yet be in the forefront of the environmental movement, it is being recognized worldwide as a major environmental pollutant. In New York City, noise is the number one quality of life complaint, far outweighing other quality of life complaints, and throughout the United States it has been noted as a major reason for people moving from their homes. Although there is a need for additional research to confirm the health/noise link, the World Health Organization has already recognized noise pollution as a serious health issue. There is certainly sufficient research to warrant warnings that noise is injurious to mental and physical health. Yet, despite this growing body of literature attesting to the relationship between noise and health impacts, government bodies have not yet invested the dollars needed to abate noise nor to educate people to the dangers of noise. Organizations such as the League for the Hard of Hearing, the Noise Pollution Clearinghouse, and the United Kingdom Noise Network have assumed the tasks of educating the public to the harmful effects of noise, of advocating anti-noise measures, and of urging public officials to move more assertively in lessening the din of our ever-increasing noisy society.
Training as a critical component of successful noise enforcement programs
Authors: Zwerling Eric
Published: September 2013

The point of application of any noise enforcement program is the enforcement officer. The quality of their training is of paramount importance in determining their efficacy in resolving complaints in the field or, failing that, in court. Some of the critical components that must be addressed in a training program are the technology, techniques and strategies of legally valid sound level measurement; documentation of measurement parameters and results; calculation of corrected source sound levels; managing the expectations of complainants; negotiations with alleged violators; and compliance determination methods for nonmetered performance standards. A strong emphasis must be on practical field measurements. The training must assist the enforcement officer to become comfortable with the process, motivating the officer to embrace the new skill, rather than resenting a new task. It is important to take into account the background of the students, professionally, and as individuals, as well as the institutional culture of their agency. The better prepared an officer is to go to court, the less likely is that possibility. A well designed and executed program, represented by its field officers, provides significant deterrence. Thirteen years of training experience at the Rutgers Noise Technical Assistance Center is reviewed.
The Schoch effect as a means to detect the principal axes of a piezoelectric crystal
Authors: Declercq Nico F. , Teklu A. , Breazeale M. A. , Degrieck Joris , Leroy Oswald
Published: September 2013

When a bounded beam is incident on a piezoelectric crystal at the right angle, surface waves are generated which result in the Schoch effect. This effect consists of the appearance of two reflected beams instead of one, with a null strip in between. The characteristics of this Schoch effect are determined by the physical properties of the solid under consideration, but also by the direction of the principal axes. Therefore, the effect can be used to determine those directions. A comparison of theory and experiments on lithium niobate is shown. This method can be used as a practical tool for determining the principle axes, since these are not visible to the eye. [Work supported by The Flemish Institute for the Encouragement of the Scientific and Technological Research in Industry (I.W.T.) and by a NATO Collaborative Linkage Grant.]
Reflection coefficient of a water-loaded monoclinic plate: Obtaining of a factorized expression
Authors: Lenoir Olivier , Guénégou Lionel
Published: September 2013

For an isotropic plate, it was shown by Schoch and used by Überall et al. that the reflection coefficient R of an elastic plate immersed in a fluid can be written in terms of the CA,S functions and the ratio τ of the acoustic impedances in the plate and in the fluid. The denominator of R is the product of the (CA,S±jτ) functions. The roots of these functions correspond to the antisymmetric (A) and symmetric (S) vibration modes of the fluid-loaded plate. In this case, the Lamb-type guided waves are the combinations of dilatational and shear waves polarized in the incident plane. In this study, we consider an orthotropic plate where the incident plane is different from a symmetry plane; therefore, everything happens as if we dealt with a monoclinic plate. In this case, the guided waves are the sum of nonpure longitudinal waves, shear waves, and SH waves. Nevertheless, it can be shown that the expression of the reflection coefficient of the monoclinic plate has formally the same factorized form as the one of the isotropic plate. This expression is numerically compared to the one obtained by the stiffness matrix method developed by Rokhlin et al.
The role of stimulus uncertainty in speech perception
Authors: Kewley-Port Diane
Published: September 2013

Among the important experimental factors that affect psychophysical measurements of speech perception is stimulus uncertainty. Charles Watson has defined stimulus uncertainty as variation in stimulus parameters from trial to trial and demonstrated its highly degrading effects on a variety of complex auditory signals. Watson, Kelley, and Wroton showed large (×10) elevation of frequency-discrimination thresholds for ‘‘word-length tonal patterns’’ under high uncertainty conditions [J. Acoust. Soc. Am. 60, 1176–1186 (1976)]. Investigations of speech, such as the perception of VOT (voice onset time) in stops [Kewley-Port, Watson, and Foyle, J. Acoust. Soc. Am. 83, 1113–1145 (1988)] and discrimination of vowel formants [Kewley-Port, J. Acoust. Soc. Am. 110 (2001)], have also demonstrated the systematic and profound effects of higher levels of stimulus uncertainty. This presentation will discuss extensions of the concept of stimulus uncertainty that demonstrate the degrading effects of the variability in more natural speech (versus synthetic speech) and longer phonetic context (including sentences) on vowel formant discrimination. Results from normal-hearing and hearing-impaired listeners demonstrating similar detrimental effects of high stimulus uncertainty will also be presented. [Research supported by NIH-NIDCD.]
Contributions of internal noise and Bernoulli variance to the variability in multiple estimates of d′.
Authors: Jesteadt Walt
Published: September 2013

Multiple estimates of d′ obtained from the same observer will vary as a result of differences in attention and other sources of internal noise, but also as a result of the variances associated with the two proportions that contribute to each d′ estimate. This second source, known as Bernoulli variance, causes the expected variance of d′ to vary a function of the true value of d′. Because estimates of d′ obtained from 2×2 matrices are discrete rather than continuous, the expected variance of the estimates cannot be specified by an equation. Miller [Percept. Psychophys. 58, 65 (1996)] has presented a method for computation of the sampling distribution of d′, for any true value of d′ and any given number of trials, and has demonstrated that a well-known approximation greatly exaggerates the variance for large values of d′. In the current paper, the standard approximation and Miller’s exact method are extended from Yes–No to the more commonly used 2IFC procedure and the effects of two standard corrections for zero cells are examined. A comparison of the theoretical results to actual data suggests that Bernoulli variance plays a greater role than internal noise in determining the variability in d′ estimates.
Measurements of underwater acoustic pressure fields using a scanning laser Doppler vibrometer
Authors: Carroll Gerard P.
Published: September 2013

Laser Doppler vibrometers (LDV) are designed to measure structural vibration velocity by sensing the phase shift in the laser signal reflected from a vibrating source. It is known that index of refraction modulations resulting from acoustic pressure distributions along a laser light path will also cause a phase shift. Simpson et al. [J. Acoust. Soc. Am. 99(4), 2521(A) (1996)] have investigated this acousto-optic phase modulation as a possible contaminating effect for underwater LDV vibration measurements. This paper will investigate acousto-optic phase modulations measured by a scanning LDV as a method for measuring pressure radiating from underwater vibrating surfaces. This is done by passing the laser beam through the radiating pressure field and measuring the backscattered laser signal which is reflected off a rigid and retroreflective surface (outside the pressure field). It is shown experimentally, using the average pressure measured with an LDV over a plane in the vicinity of a vibrating structure, that the pressure at a far-field location normal to the plane can be determined.
Cylindrical transducers to generate and detect axisymmetric waves in a pipe
Authors: Kim Jin O. , Hwang Kyo-Kwang , Lee Jung-Goo , Jeong Hyung-Gon
Published: September 2013

This paper presents the radial vibration characteristics of piezoelectric cylindrical transducers and the application of the transducers to the generation and detection of axisymmetric longitudinal waves in a pipe. Dynamic differential equations of piezoelectric radial motion derived in terms of radial displacement and electric potential and mechanical and electric boundary conditions have yielded a characteristic equation for radial vibration of the radially polarized piezoelectric cylinder. Theoretical calculations of the fundamental natural frequency have been compared with numerical and experimental results for transducers of several sizes, and have shown a good agreement. It has been shown that the piezoelectric natural frequency of the fundamental mode for radial vibration in a cylindrical transducer depends mostly on the radius rather than on the thickness of the cylinder. Experiments have been performed in empty and water-filled pipes equipped with the transducers that were used for transmitting and receiving axisymmetric elastic waves in the pipe wall. The measured wave speeds have been compared with the analytical ones. This work has demonstrated the feasibility of using cylindrical transducers and pipe waves for the determination of the mass density and, eventually, the flow rate of the liquid in a pipe.
Actuator/sensor placement optimization for vibration control based on finite element model of the car chassis
Authors: Seba Bouzid , Nedeljkovic Nikola , Lohmann Boris
Published: September 2013

The finite element method is a convenient approach to model the structures with complex geometry and subjected to complicated boundary conditions. However, the order of the obtained model using FEM strategy is large. Therefore, the control design and implementation based on the FEM model turns out to be complicated (sometimes not feasible). Hence, the order reduction techniques are inevitable to reduce the size of the system obtained with FEM. The reduced model is then used to explore and to optimize the system in terms of collocated actuator/sensor positioning problem. In this paper, we suggest a strategy to optimize the location of the electromechanical actuators in the car chassis subframe for vibration control. The proposed method can be formulated using an optimization problem with constraints which are introduced to consider the spill over effect resulted from the neglected higher modes in the model reduction part (which affects the stability of the closed loop system) and to ensure the minimum controllability of individual modes. The optimization algorithm is used to select three optimal positions of the collocated actuator/sensor among 298 possible positions.
Optimal sensor placement in highly variable noise fields to increase detection
Authors: DelBalzo Donald R. , Rike Erik R.
Published: September 2013

Ambient noise (AN) is highly variable in littoral environments. AN predictions are often smoothed to produce mean estimates in support of signal detection. In a complex AN environment, the optimal placement of sensors for detection also depends on the spatial and temporal variance of AN. The recent development of the Dynamic Ambient Noise Model (DANM) allows accurate, detailed estimation of noise statistics. DANM was used to produce space- and time series of directional noise based on discrete ship tracks. This work describes a fast optimization scheme that exploits nonhomogeneous noise variability to select optimal locations that maximize detection. A standard, nonoptimal approach for choosing locations is sequential and myopic. A better approach is combinatorial; i.e., consider all possible sensor sets and choose the best. This optimal approach is often computationally prohibitive. Brown’s iterative algorithm combines elements of both algorithm types to achieve rapid results. Brown’s algorithm was modified and used to demonstrate the importance of nonhomogeneous noise statistics. The results show a significant improvement in probability of detection when DANM AN statistics are considered while choosing optimal sensor locations. This work has application to design of optimal sonobuoy field patterns. [Work sponsored by ONR under the LADC project.]
Free-field equivalent shape of scattering conformal microphone arrays
Authors: Moquin Philippe , Dedieu Stephane
Published: September 2013

When an array is placed upon an acoustic scatterer, the interelement spacing of the array appears to be different from free field conditions [J. Meyer, J. Acoust. Soc. Am. 109, 185–193 (2001)]. This manifests itself primarily as a nonlinearity in the interelement phase difference. Ideal scatterers (rigid and nonconducting) can be used to understand these effects. A spherical scatterer with a circular array serves as a first example since it has an analytical solution. To help understand the effect, equivalent shape of a free-field array can be calculated. Numerical simulation and measured results on a telephonelike shape with an elliptical array will serve to illustrate that the results from the sphere can be used as a guide for estimating the scattering effects that can be expected in a more complex shape.
Ray and travel time stability in weakly range-dependent sound channels
Authors: Beron-Vera Francisco J. , Brown Michael G.
Published: September 2013

Ray path and travel time stability are investigated in environments consisting of a range-independent background on which a weak range-dependent perturbation is superimposed. Theoretical arguments suggest and numerical results confirm that both ray path and travel time stability are strongly influenced by the background sound speed profile. Both ray path and travel time stability are shown to increase with increasing magnitude of α(I)=(I/ω)dω/dI, where 2π/ω(I) is the range of a ray cycle (double loop in a deep ocean sound channel) and I is the ray action variable. This behavior is illustrated using internal-wave-induced scattering in deep ocean environments and rough surface scattering in upward refracting environments. [Work supported by ONR.]
Broadband normal-mode computations within a multiprocessing environment
Authors: Stotts Steven A. , Van Zee Field G.
Published: September 2013

A technique to facilitate normal-mode modeling within a multiprocessing environment is presented using the Message-Passing Interface (MPI) communication library. Portability and standardization were the driving factors for using MPI as the multiprocessor implementation. Using only a minimal set of commands, an example algorithm illustrates the approach as a basis to transform existing models to perform computations via multiprocessors. Applications to propagation modeling are given with an emphasis on broadband normal-mode computations. A static approach to equalizing processor workload for normal-mode computations utilizes the linear dependence of mode number with frequency. The area under a curve representing the mode number versus frequency is used to determine the loading. An assumption of equal area implying equal loading determines the beginning and ending frequency increments for each processor. Comparisons with other approaches to processor loading for optimizing speedup time are given. A determination of the optimal number of processors for several examples of broadband normal-mode computations using a subroutine version of the Navy Standard NAUTILUS will be presented. Implementing this approach into more advanced models such as geoacoustic inversions will be discussed.
Benchmark comparisons of a modified coupled normal mode method (Swamp) and commonly used range dependent methods
Authors: Werby Michael
Published: September 2013

The algorithm Swamp has been benchmarked and documented and has been effectively used in a variety of studies [see http://www.ucs.louisiana.edu/∼nxs7560]. Here the method is augmented in two ways. First, a more general layering scheme is implemented which allows for a broad angular spectrum required to replicate near field effects. Second, by making use of pseudo unitary operators the method is extended to a two-way coupled mode algorithm. The method is tested and compared with available methods in current use. Further, it is possible to make use of bandedness and this improves the time of calculation significantly and allows the resulting code to be used for very high frequencies. Benchmark calculations are presented for several examples.
Statistical modeling of sonar performance and its variance due to ocean fluctuations
Authors: Chen Chi-Fang , Yang Zheng-Ru , Yuan Mei-Chun , Chang Yuan-Ying
Published: September 2013

Sonar performance can be characterized by its detection range, which is determined by the sonar equation. The sonar equation includes parameters of sonar systems, environments, and the detection algorithms. Though the detection algorithm is itself a statistical means, it does not describe the relationship between the statistical properties of the environmental parameters with the detection range. This paper presents a statistical model for detection range based on the statistical properties of the environments, namely transmission losses. Temperature data from local moorings and VLA in ASIAEX-SCS are used to establish an ensemble samples for sound-speed profiles, and transmission loss curves are generated, thus the ensemble samples for TLs. The resultant detection range and its error bar are estimated for the Continental Shelf region in the South China Sea.
Prediction of broadband nonuniform time-dependent acoustic fields in enclosures with diffuse reflection boundaries using energy-intensity modes
Authors: Bliss Donald B. , Franzoni Linda P.
Published: September 2013

A new analysis of high-frequency broadband reverberant sound fields in rooms with diffuse reflection boundaries is described. Depending on shape, source location, and distribution of wall absorption, rooms exhibit spatial variation in steady-state mean-square pressure and also spatial dependence of decay time characteristics. The room boundaries can be replaced by a distribution of uncorrelated broadband directional energy-intensity sources. In steady state with diffuse reflection boundaries, the interior pressure field produced by these sources satisfies Laplace’s equation. The mean-square pressure field is expressed as a sum of constituent modes. The intensity field, which is related to the pressure field in a complex way, can be calculated for each mode. Boundary conditions relate averaged intensity and pressure. The mean-square pressure is expressed in terms of the modal sum. Lower order modes are responsible for the overall smooth spatial variation in the reverberant field; higher modes account for more rapid local variations near walls due to changes in wall properties. In the transient problem, the spatial eigenmodes decay at different rates, leading to a spatial redistribution of reverberant energy, and causing the decay curves to be a function of position in the room. Sample calculations and comparisons with other solution methods are presented.
An acoustical analysis of a room with a concave dome ceiling element
Authors: Utami Sentagi S.
Published: September 2013

Concave surfaces are often considered detrimental in room acoustics, especially because of the impact they have on the distribution of sound energy. This paper explores certain acoustical characteristics and anomalies found in spaces below concave dome ceiling elements. The architectural design of the Darusshollah mosque in East Java, Indonesia is used as a case study with specific spatial and functional concerns. Investigations of the mosque have been conducted through both a 1:12 scale model and a computer model that utilizes ray tracing and image source methods. Analysis techniques are discussed. Results are presented and compared to provide useful insights into the acoustics of such distinctive environments.
Acoustics of early music spaces from the 11th to 18th century: Rediscovery of the acoustical excellence of medium-sized rooms and new perspectives for modern concert hall design
Authors: Bassuet Alban
Published: September 2013

The acoustical characteristics of 50 rooms that played a prominent role in the history of music between the 11th and 18th centuries were studied. The rooms include basilicas, oratorios, organ churches, and the great halls and courts of the European palaces. The research provides an understanding of the acoustical features that suit the early music repertoire, and how these rooms achieved an enhanced emotional engagement through their unique acoustical characteristics. This paper provides a summary of the acoustic measurements, which include binaural and B-format recordings in each of the rooms, and presents a unique new approach to understanding their subjective characteristics through detailed analysis and auralization of their 3-D impulse response. The study shows that the timing and direction of reflections in three dimensions is critically important to defining the subjective characteristic of a room. The results emphasize the importance of developing techniques to understand the 3-D impulse response and using auralization techniques for interpreting results and making subjective judgments. The enhanced musical experience that is achieved in these early rooms offers an invitation to rethink modern acoustics and to develop a new design approach that focuses more strongly on the subjective response and emotional engagement of the music.
Acoustical phenomenon in ancient Totonac’s monument
Authors: Sánchez-Dehesa José , Håkansson Andreas , Cervera Francisco , Meseguer Francisco , Manzanares-Martínez Betsabé , Ramos-Mendieta Felipe
Published: September 2013

The circle of gladiators is a monument built by Totonac Indians in the ceremonial site of Cempoala, which is located near Veracruz (Mexico). The city is believed to date to around 1200 A.D. The monument is a round structure with crenellated wall tops, and it has a diameter of 13.4 m. Though the deterioration of this monument is noticeable, it presents a singular acoustical phenomenon whose strength had to be probably extraordinary on the date of its construction. In brief, along any diameter in the circle, one can find two focal points such that if one person speaks on one focus, another person located on the other hears the sound reinforced. In other words, this circular place acoustically behaves as if it were elliptical. Here, we report the experimental characterization of the phenomenon and present a theoretical explanation. Also, the intentionality of the Totonacs is speculated since these people are associated with the Mayan culture, which is known by its realizations of environments with astonishing sonic properties. [Work supported by CEAL-UAM of Spain.]
Acoustic backscatter models of fish: Gradual or punctuated evolution
Authors: Horne John K.
Published: September 2013

Sound-scattering characteristics of aquatic organisms are routinely investigated using theoretical and numerical models. Development of the inverse approach by van Holliday and colleagues in the 1970s catalyzed the development and validation of backscatter models for fish and zooplankton. As the understanding of biological scattering properties increased, so did the number and computational sophistication of backscatter models. The complexity of data used to represent modeled organisms has also evolved in parallel to model development. Simple geometric shapes representing body components or the whole organism have been replaced by anatomically accurate representations derived from imaging sensors such as computer-aided tomography (CAT) scans. In contrast, Medwin and Clay (1998) recommend that fish and zooplankton should be described by simple theories and models, without acoustically superfluous extensions. Since van Holliday’s early work, how has data and computational complexity influenced accuracy and precision of model predictions? How has the understanding of aquatic organism scattering properties increased? Significant steps in the history of model development will be identified and changes in model results will be characterized and compared. [Work supported by ONR and the Alaska Fisheries Science Center.]
High-frequency acoustic volume scattering from zooplankton and moving oceanic microstructure
Authors: Lavery Andone C. , Wiebe Peter H. , Schmitt Raymond W. , Stanton Timothy K. , Ross Tetjana , Lawson Gareth , Copley Nancy , Fisher Karen E. , Wolk Fabian
Published: September 2013

It is well accepted that high-frequency acoustic scattering techniques can be used to perform rapid, synoptic surveys of fish and zooplankton over relevant spatial and temporal scales. However, the use of these remote sensing techniques to probe small scale physical processes, such as oceanic microstructure, has not been fully accepted, or exploited. Yet there is a growing body of evidence in the form of both laboratory and field measurements suggesting that their use is feasible. Discrimination of scattering from microstructure versus zooplankton, which span similar spatial scales, is typically a limiting factor. Currently, acoustic discrimination of turbulence from zooplankton relies on either source of scattering being dominant as well as on the availability and accuracy of scattering models. A model for scattering from oceanic microstructure that includes fluctuations in the density and sound speed is presented. The effects on scattering from a layer of microstructure with a mean fluid velocity are discussed. Backscattering predictions are made based on data collected in Hudson Canyon with a tethered free-falling high-resolution vertical microstructure profiler, and compared to two-frequency acoustic data (120 and 420 kHz). The contribution to scattering from zooplankton is also estimated from nearby depth-resolved net tows together with zooplankton scattering models.
Sonoporation of cell using therapeutic ultrasound for drug and gene delivery
Authors: Pan Hua , Sieling Fred , Zhou Yun , Wang Hesheng , Cui Jianmin , Deng Cheri
Published: September 2013

Recent studies of ultrasound methods for targeted drug delivery and nonviral gene transfection revealed new, advantageous possibilities. These studies utilized ultrasound contrast agents, commonly stabilized microbubbles, to facilitate delivery and suggested that ultrasound delivery resulted from cell sonoporation, the formation of temporary pores in the cell membrane induced by ultrasound. In this study, voltage clamp techniques were used to obtain real-time measurements of sonoporation of single Xenopus oocytes in the presence of Optison. Ultrasound increased the transmembrane current as a direct result of decreased membrane resistance due to pore formation. We observed a distinct delay of sonoporation following ultrasound activation and characteristic stepwise increases of transmembrane current throughout ultrasound duration. We discovered that the resealing of the cell membrane following ultrasound exposure required calcium entering the cell through ultrasound-induced pores.
HIFU-induced gene activation in vitro
Authors: Liu Yunbo , Zhong Pei , Kon Takashi , Li Chuanyuan
Published: September 2013

This work investigated the inducible gene activation in cancer cells that were sublethally injured during HIFU treatment. HeLa cells were transfected by an adenovirus vector that encodes GFP under the control of hsp70B promoter, leading to about 65% transfection efficiency. A volume of 10 μL transfected HeLa cells in suspension (5×107 cells/ml) were placed at the bottom of a PCR tube so that the cell suspension could be heated to a peak temperature of 50°C, 60°C, and 70°C for 120, 10, and 1 s, respectively, by a focused 1.1-MHz HIFU transducer operated at a peak negative pressure of −2.7 MPa at different duty cycles. One day after HIFU treatment, cell viability was determined to be 63%, 35%, and 18%, respectively, based on Trypan Blue exclusion test. Importantly, in all test groups, inducible GFP expression was detected in about 40%–50% of the surviving cells with GFP intensity increased by 25-fold based on flow cytometry analysis. These results demonstrate that even under the short exposure duration of HIFU treatment, inducible gene expression could be produced in sublethally injured cell population in vitro. Further studies are underway to explore the optimal HIFU condition for gene activation in vivo.