bluuebunny/crossref_metadata_2025 huggingface dataset:
Bow response to the string it is bowing
Authors: Schumacher Robert T.
Published: October 2013

The force that a bowed string exerts on the bow can be reconstructed from the forces on the string’s termination. By using one or more accelerometers attached to the bow, the response of the bow to that reconstructed force can be recorded. Bow responses will be shown that were obtained using a bowing machine. At some harmonic frequencies of the string the signal from the longitudinal standing wave excited on the bow hair allows determination of the velocity of propagation of that wave. The consequence of the variable excitation of various harmonics of the standing wave as the bow stroke progresses is a rapidly changing excitation of the bows various normal modes. Three data channels, requiring at least a 128 kHz sampling rate for E-strings, are required for bow force reconstruction and motion detection of the bow. The validity of substituting the force of the string on the bridge instead of the reconstructed bow force is explored. That allows a reduction of the minimum number of data channels from three to two, a reduction in the necessary sampling rate, and use of a bow stroke by a player instead of a bowing machine.
Analysis over the new data treatment method developed by the community directive 2002/49/ce about environmental noise management
Authors: Cueto Jose Luis , Rivas Silvia , Hernandez Ricardo
Published: October 2013

Nowadays a European Directive develops useful procedures in order to evaluate, by means of index, the acoustic pollution affecting urban areas. To apply properly those methods, it is necessary to use a long data sequence. Is usual to find in this kind of series some peculiar measures or events that could change indicatively our acoustic pollution index data. So, we suggest a simple data treatment method as a first step in the way of developing a better process of acoustic index construction. This methodology would permit us to introduce the acoustic climate concept.
A method to separate contribution from coherent and interfering inputs
Authors: Lenchine Valeri V. , Wee Hoon , Joo Jae-Man , Oh Sang-Kyong
Published: October 2013

Acoustical development tasks frequently involve the identification of contribution from different sources. A conventional way to detect principal exciters is to separate signals that are completely incoherent between each other and interfering inputs. However the method lacks physical meaning as the principle contributors are coherent. Moreover a conventional technique involves assumptions about independent inputs and the kind of dependence between interfering signals. It is suggested to extract noninterfering but partly coherent virtual signals from measured inputs that are considered as physical inputs. The procedure is based on the determination of a virtual input spectra matrix. As for many practical tasks measured inputs have approximately the same magnitudes of auto, cross spectra and high mutual coherence detection of principal contributors encounters ambiguity. A minimal principle value deviation is employed as criteria to choosing an appropriate virtual input spectra matrix. An example involving acoustical development of a multi indoor units air conditioner that is equipped by compressor generating pressure pulsation into discharge and suction pipeline is considered. These effects cause excessive sound emission of indoor units. The proposed technique is used for the separation of interfering coherent inputs (discharge and suction pressure). It enabled us to develop effective ways for the air conditioner noise reduction.
TWA Flight 800, explosion airblast unexplained
Authors: Reed Jack W.
Published: October 2013

TWA Flight 800 disintegrated off Long Island, NY, on 16 July 1996. Immediate reports from other flyers described what appeared as attacking missiles. Search for terrorists began quickly, with over 1000 FBI agents to collect debris, interview eyewitnesses, and analyze sightings to give a missile launch point. They found no evidence of criminal attack, and turned investigations over to the NTSB to find some accidental cause. The ‘‘empty’’ central fuel tank was determined to be the likely explosion source. On the other hand, early witnesses reported a ‘‘loud’’ bang after seeing a great fireball fall from the sky, but at 15 km or greater range, they saw and heard two different events. This acoustic discrepancy has not been adequately investigated. When finally released, FBI reports from more than 200 ‘‘ear-witnesses’’ give similar observations. Their loudness reports confirm that at least a ton of TNT equivalent explosion had occurred. NASA acousticians engaged by NTSB, however, through spectral analysis techniques for sonic booms, concluded that a 10-kg TNT explosion, from detonating fuel tank vapors, could be heard on Long Island. Evidence for a much larger yield is presented here, but its form remains a mystery.
Reconstruction of acoustic radiation from vibrating objects in a half space using hybrid nearfield acoustical holography
Authors: Zhao Xiang , Wu Sean F.
Published: October 2013

Hybrid nearfield acoustical holography (NAH) [Wu, J. Acoust. Soc. Am. 113, 2252 (2003)] is utilized to reconstruct the vibro-acoustic fields generated by vibrating structures in half space. These hybrid formulations are derived from a modified Helmholtz equation least-squares method, where the field acoustic pressure is expanded in terms of both outgoing and incoming spherical waves, and the Helmholtz integral formulations implemented by the boundary element method (BEM). To overcome the ill-conditioning difficulties in the resultant matrix equations, regularization techniques such as the method of Tikhonov and generalized cross validation are employed. The main advantage of this hybrid approach is that satisfactory reconstruction can be obtained with relatively few acoustic pressure measurements taken over a conformal surface around the source. This is because a large portion of the input data is regenerated by the modified HELS, but not actually measured. Hence, the efficiency of reconstruction is enhanced. If the same number of measurements is used in an inverse BEM code, the reconstructed vibro-acoustic quantities on the source surface may be distorted. Numerical examples of a dilating and an oscillating sphere and a cylinder with spherical endcaps in half space are demonstrated. [Work supported by NSF.]
Reconstruction of the surface normal acoustic intensity from noisy pressure data by regularized Helmholtz equation least squares method
Authors: Semenova Tatiana , Wu Sean F.
Published: October 2013

Reconstructing the normal acoustic intensity on a source surface from the field pressure measurements is critical in identifying the noise sources and their transmission paths. In this paper, we consider the reconstruction of time-averaged normal acoustic intensities from noisy pressure data using the Helmholtz equation least squares (HELS) method with regularization by truncated singular value decomposition or the method of Tikhonov. The regularization parameter is calculated by generalized cross validation, L-curve, and quasioptimality criterion and the best solution is chosen. Numerical results show that the normal velocity reconstruction is more sensitive to noise in the input data than the pressure reconstruction, and depends critically on the choice of the regularization parameter. It is found that the HELS-based Dirichlet-to-Neumann (DtN) map has a similar accuracy as compared to the Green’s formula-based DtN map with Tikhonov regularization for 1% noise or larger in the input data, provided that HELS converges sufficiently fast. Moreover, determining the surface normal velocity from the reconstructed surface pressure is more stable than reconstructing it directly from the field pressure data. It is concluded that a regularized HELS, when it converges fast enough, can be an easy-to-use and cost-effective tool for intensity reconstruction [Work supported by NSF.]
Spatio-temporal gradient signal processing for reconstructing scattered wave fields
Authors: Teramoto Kenbu , Tsuruta Kohsuke
Published: October 2013

This paper presents a subspace signal processing method which detects the scattered sound waves based on the spatio-temporal gradient analysis over the Lamb wave field. The proposed method has an ability to classify the surface acoustic wave field through the rank of the covariance matrix defined over the four-dimensional vector space which is spanned by the following components: a vertical displacement, its vertical velocity, and a pair of shear strains of the plate surface. The covariance matrix provides the information about cracks. When a unique sound source exists on the surface without any cracks or scatterers, the rank of the covariance matrix is reduced to two. Increasing the rank up to three, however, one or more scatterers exist on the surface. Therefore, by the singular value decomposition (SVD) of the covariance matrix, optimal, orthonormal bases are obtained. In formulating the scattered wave field by the unknown object, its best reconstruction, in the LMS sense, can be obtained by the sum of orthogonal vector spaces. The computational process in a wave field near the cracks is discussed and their physical meanings are investigated through DTD-simulations and acoustic experiments.
Reflection and transmission coefficients in terms of pressure for Biot’s compressional waves and the importance of the shear modulus for Biot’s slow wave
Authors: Ohkawa Keiichi
Published: October 2013

The method to determine reflection and transmission coefficients in terms of pressure at the fluid–sediment interface is presented. In general, reflection and transmission coefficients derived from the Biot theory have been computed using displacement potentials. Within the framework of the Biot theory it is assumed that the fluid-saturated unconsolidated sediment has low values of frame bulk and shear moduli relative to the other moduli of the medium and the shear wave is negligible. This enables to treat the Biot theory easier. By introducing effective densities, reflection and transmission coefficients can be treated as if the medium is a fluid. This approach using the models decoupling method is fairly different from the effective density fluid model [K. Williams, J. Acoust. Soc. Am. 110, 2276–2281 (2001)]. It is shown that pressure coefficients give the same results as computed using displacement potentials. This method gives the advantage of directly computing the pressure for problems of reflection, transmission, and scattering. However, boundary conditions should be carefully treated. The pressure coefficient for Biot’s slow wave cannot be accurately calculated when the equilibrium of solid pressure at the interface is constrained instead of the normal traction. This disagreement demonstrates that the shear modulus plays an important role in the generation of the slow wave.
Linear coupled electrokinetic-acoustic behavior of consolidated and unconsolidated granular materials
Authors: Block Gareth , Harris John G. , Chotiros Nicholas
Published: October 2013

Two electrokinetic (EK) techniques are being developed to study wave propagation in consolidated and unconsolidated granular materials. In contrast to the more common acoustical techniques, EK transduction utilizes the electrokinetic coupling between sediment grain surface chemistry and pore fluid motion. When Biot theory is applicable, coupled electrokinetic-Biot theory predicts that a macroscopic electric potential is generated by fluid motion in electrolyte-saturated porous media. (Our previous research on the reciprocal case—of creating a pressure wave by applying a high voltage impulse to electrolyte-saturated sediments—has been presented at recent ASA meetings.) To assess the validity of Biot theory as a model of ocean sediments, various EK measurements were taken in the laboratory. Preliminary data using silica sand, as well as unconsolidated and consolidated (sintered) glass microspheres, will be presented. We will also describe the coupled electrokinetic-Biot theory, the underlying volume-averaged poroelastic model upon which it is based, and related issues in homogenization theory. [Work supported by ONR, Ocean Acoustics.]
Overview of vector sensors for undersea applications
Authors: McEachern James F.
Published: October 2013

An overview of vector sensors for sonar applications is presented. The most prolific use of vector or pressure gradient sensors has been in directional sonobuoys to accomplish effective directional measurements with a sensor that is much smaller than the signal wavelength. Common characteristics, implementation issues, and self noise sources of directional hydrophones are reviewed. Arrays of vector sensors began to emerge in the 1980s and have the attractive property of being able to provide substantially higher directivity for a smaller equivalent aperture than that required for a scalar (omnidirectional) sensor array. Dyadic sensors bring additional directivity but development is required to realize them in a compact configuration. Future applications of vector sensors are discussed. The limited amount of information relative to the ocean acoustic vector fields is noted as a corollary technological requirement for the widespread adoption of vector sensors in sonar systems.
Shock wave lithotripsy (SWL) induces significant structural and functional changes in the kidney
Authors: Evan Andrew P. , Willis Lynn R. , Lingeman James E.
Published: October 2013

The foundation for understanding SWL-injury has been well-controlled renal structural and functional studies in pigs, a model that closely mimics the human kidney. A clinical dose (2000 shocks at 24 kV) of SWL administered by the Dornier HM3 induces a predictable, unique vascular injury at F2 that is associated with transient renal vasoconstriction, seen as a reduction in renal plasma flow, in both treated and untreated kidneys. Unilateral renal denervation studies links the fall in blood flow in untreated kidneys to autonomic nerve activity in the treated kidney. SWL-induced trauma is associated with an acute inflammatory process, termed Lithotripsy Nephritis and tubular damage at the site of damage that leads to a focal region of scar. Lesion size increases with shock number and kV level. In addition, risk factors like kidney size and pre-existing renal disease (e.g., pyelonephritis), can exaggerate the predicted level of renal impairment. Our new protection data show that lesion size can be greatly reduced by a pretreatment session with low kV and shock number. The mechanisms of soft tissue injury probably involves shear stress followed by acoustic cavitation. Because of the perceived enhanced level of bioeffects from 3rd generation lithotripters, these observations are more relevant than ever.
Generation of shear waves as an effective mechanism of dynamic load of the lithotripter shock wave on the kidney stone
Authors: Sapozhnikov Oleg A. , Cleveland Robin O. , Bailey Michael R. , Crum Lawrence A.
Published: October 2013

A number of stone comminution mechanisms have been studied in lithotripsy. Except cavitation erosion, these mechanisms (namely, spallation, dynamic fatigue, shear, and circumferential compression) are associated with stresses generated in the stone by the shock wave. The mechanical load on the stone depends on the waveform and stone structure, size, and shape. We modeled the propagation of lithotripter shock waves through a cylindrical stone with a finite differences simulation based on Lame’s equation. The stone parameters were similar to those of natural kidney stones. A new mechanism of tensile stress generation is predicted that may be 5–10 times more efficient than spalling. Shear elasticity of the stone gave rise to the peak tensile strain in the bulk of the stone; this strain occurs near the stone axis due to coherent arrival of shear waves from the front edges of the stone. The position of the region of maximum strain and direction of corresponding tensile forces is similar to those predicted by the spalling mechanism. The modeling also showed that circumferential compression is not activated by the dynamic load produced by a short shock wave typical for lithotripsy. [Work supported by NIH PO1 DK43881, RO1 DK55674 and FOGARTY, CDRF, ONRIFO, and NSBRI.]
Nonlinear acoustic techniques for landmine detection: Tuning curves and two-tone tests
Authors: Korman Murray S. , Sabatier James M. , Fenneman Douglas J.
Published: October 2013

Measurements of the top surface vibration of a buried (inert) VS 2.2 anti-tank plastic landmine reveal significant resonances in the frequency range between 80 and 650 Hz. Resonances from measurements of the normal component of the acoustically induced soil surface particle velocity (due to sufficient acoustic-to-seismic coupling) have been used in detection schemes. Since the interface between the top plate and the soil responds to pressure fluctuations nonlinearly, characteristics of landmines, the soil, and the interface are rich in nonlinear physics and allow for new methods of buried landmine detection not previously exploited. Tuning curve experiments (revealing ‘‘softening’’ and a back-bone curve linear in particle velocity amplitude versus frequency) help characterize the nonlinear resonant behavior of the soil-landmine oscillator. When two primary waves f1 and f2 drive the soil over the mine, a rich spectrum of nonlinearly generated tones is measured with a geophone on the surface over the buried landmine in agreement with Donskoy [Proc. SPIE 3392 (1998); 3710, 239–246 (1999)]. In profiling, particular nonlinear tonals can improve the contrast ratio compared to using either primary tone in the spectrum. [Work supported by the United States Army Communications-Electronics Command Night Vision and Electronic Sensors Directorate.]
Constitutive characterization of vocal fold viscoelasticity based on a modified Arruda-Boyce eight-chain model
Authors: Chan Roger W.
Published: October 2013

Previous studies have shown that vocal fold tissues exhibit nonlinear viscoelastic behavior under different loading conditions. Hysteresis and strain rate dependence of stress–strain curves have been observed for vocal fold ligament and muscle tissues when subjected to sinusoidal tensile loading. Nonlinear viscoelastic response and tissue failure have also been described for vocal fold mucosa subjected to constant strain-rate tests under large-strain shear. These findings cannot be adequately described by the traditional constitutive formulations of linear and quasilinear viscoelasticity. This study attempts to characterize some nonlinear behavior of vocal fold tissues under tensile loading based on a modified version of the Arruda-Boyce (Bergström-Boyce) hyperelastic model for polymers, which has been shown to adequately predict the rate-dependent behavior of some elastomers and biological tissues. Results indicated that the model was only capable of describing the relatively linear portion of the nonlinear stress–strain curves of the vocal fold muscle (at strain smaller than 20%), while failing to predict the exponential increase of stress at higher strain. However, the model was capable of predicting the dependence of stress on strain rate reasonably well. This finding was consistent with the model’s assumptions on the constitutive behavior of the two constituent polymer networks.
Use of loud phonation as a voice therapy technique for children with vocal nodules
Authors: Kobayashi Noriko , Hirose Hajime , Nishiyama Koichiro
Published: October 2013

For the treatment of vocal nodules, educational programs for vocal hygiene and voice training for acquisition of correct phonation are essential. In the case of children, special considerations are necessary as some of their vocal behaviors and reaction to voice disorders are different from those of adults. In this study, a voice therapy program for child vocal nodules were developed and good results were obtained for six children. They were four boys and two girls (Age: 4–11 yr) and bilateral nodules were found for all of them. In addition to a conventional vocal hygiene program for children, correct production of loud voice (so-called gBeltingh) was the major focus of the voice therapy as the visual inspection of the larynges and perceptual evaluations of the voice revealed inappropriate loud voice production with laryngeal constriction in all children. After 5–24 voice therapy sessions, disappearance of the nodules was found in five children and the reduction of the nodule sizes was found in one child. Improvement of the GRBAS scores, longer maximum phonation time, and extension of vocal ranges were found after the completion of the therapy programs.
Environmentally associated signal-to-interference variability in low-frequency active sonar
Authors: Cable Peter G.
Published: October 2013

An analysis has been conducted of the spatial and temporal variability of target echo-to-interference measurements made during Area Characterization Test I (ACT I) in 1992 on the West Florida Shelf in the Gulf of Mexico. The measurements were made for five bistatic geometries using explosive sources, a bottom-mounted horizontal receiving hydrophone array and an echo repeater ‘‘target’’ in 180 m depth water under downward refracting acoustic conditions. The bottom at the ACT I site was nearly flat of sand-silt-clay composition, and oceanographic and meteorological conditions were very quiescent during the test. In all respects these measurements could be described as having been in a quiet, well-behaved sonar environment. The observed temporal (standard deviation of 1.6 dB) and spatial (standard deviation of 2 dB) variability of the received signal-to-interference will be discussed in terms of physical causes and measurement error. [Work supported by ONR.]
Effects of the propagation environment on coherence of underwater broadband acoustic signals
Authors: Romond Rachel , Bradley David L. , Culver R. Lee
Published: October 2013

Acoustic and environmental measurements were collected in 550 m of water approximately 2.5 km east of San Clemente Island, CA over a 4-day period in August 2002. Continuous-wave and frequency-modulated pulses with center frequencies of 20 and 40 kHz were transmitted over a 1 km distance. Four projectors were located between 10 and 70 m depth, and five receivers were positioned between 40 and 220 m. Data from an anemometer, wave rider buoy, acoustic Doppler current profiler and towed conductivity-temperature-depth array were recorded simultaneously over the test period to characterize the marine environment. The extensive set of environmental data provided a basis for boundary condition and water column characterization. The most significant environmental dynamic was found to be tidally related water current. The environmental conditions were input into a propagation model to predict the acoustic signal structure and propagation behavior in the measured environment. Predictions of acoustic propagation parameters such as time fluctuation, amplitude fluctuation, and effect of bandwidth will be compared to results from on-site acoustic measurements. [Work supported by ONR Code 321US under the ARL Program.]
Acoustic source model input parameter simulation via hydrodynamic modeling of breaking waves
Authors: Means Steven L. , Szymczak William G.
Published: October 2013

Low-frequency source models for sound generation from breaking waves based on the collective oscillation of an entrained bubble cloud require a number of input parameters, e.g., void fraction, cloud size, etc. The present effort seeks to obtain simulations of these parameters using a volume of fluid type hydrodynamic model (BUB) to simulate the air entrainment processes occurring within a breaking wave. The constraint that mass is conserved and energy is nonincreasing is a unique feature of the BUB code that allows it to handle liquid collisions and violent free surface motions appropriately. Simulations of breakers of both spilling and plunging type will be presented along with their simulated acoustic source model input parameters. The simulations, in the waves reference frame, will be compared against video of breaking waves obtained in a wave tank at the University of Maryland with a high-speed, wave-following digital camera. Relationships between the simulated acoustically relevant hydrodynamic parameters and characteristics of breaker-generated acoustic signatures measured concurrently within the wave tank will be identified. [Work supported by ONR base funding at NRL.]
Bubble and bubble cloud excitation
Authors: Gopolan Harish , Carey William M. , Roy Ronald R.
Published: October 2013

Bubbles, spray, splash, and clouds are formed by breaking waves and have been shown to be responsible for the production of sound. In the low-frequency-region, i.e., 20–500 Hz, the oscillation of the cloud as a whole is thought to be responsible for the radiation of sound. This paper treats the radiation of individual bubbles by first reviewing the nonlinear bubble dynamic equations and the subsequent linearized equations. Transient solutions are then derived for several initial conditions using the Laplace transform method and are compared to individual bubble experiments to determine and bracket the radiated energy. Compact bubble clouds are shown by use of a multipole expansion to be described by a dampened simple harmonic oscillator equation. The compact cloud is first excited by an initial compression and then by subresonant energy contributions from individual bubbles oscillating at much higher resonance frequencies.This paper compares the radiated energy from fundamental excitation mechanisms. We provide a qualitative answer to the question how the bubble cloud is excited and how it radiates sound. The differences between possible excitation mechanisms are shown to be significant.
Correlation of underwater ambient noise with wind speed in extreme conditions
Authors: Newcomb Joal J. , Hillstrom Wesley R. , Goodman Ralph R.
Published: October 2013

During August 2002, the Littoral Acoustic Demonstration Center (LADC) deployed three Environmental Acoustic Recording System (EARS) buoys, at approximately the same location in the northern Gulf of Mexico, in water depths of 645 m to 1034 m. The hydrophone of each buoy was approximately 50 m from the bottom. During the experiment, Hurricane Lili passed within approximately 116 nautical miles west of the EARS buoys. The proximity of this hurricane to the EARS buoys, in conjunction with wind speed data from three nearby NOAA weather buoys, allows for the direct correlation of underwater ambient noise with wind speed. During hurricane conditions, it is expected that the noise contribution due to local shipping would be absent. Time-series data from the shallowest and the deepest of the EARS buoys were processed to yield calibrated spectral levels. These spectra are compared to corresponding spectra derived from Wenz. In the wind-dependent frequency range, a general consistency of agreement is observed in spectral shape with the Wenz spectra and the calibrated spectral levels. General consistency is also observed with the NOAA buoy data and Beaufort scale estimates. Shallow water noise levels are generally higher than temporally corresponding deep-water levels. [Research supported by ONR.]
High energy devices versus low energy devices in orthopedics treatment modalities
Authors: Schultheiss Reiner
Published: October 2013

The orthopedic consensus group defined in 1997 the 42 most likely relevant parameters of orthopedic shock wave devices. The idea of this approach was to correlate the different clinical outcomes with the physical properties of the different devices with respect to their acoustical waves. Several changes in the hypothesis of the dose effect relationship have been noticed since the first orthopedic treatments. The relation started with the maximum pressure p+, followed by the total energy, the energy density; and finally the single treatment approach using high, and then the multiple treatment method using low energy. Motivated by the reimbursement situation in Germany some manufacturers began to redefine high and low energy devices independent of the treatment modality. The OssaTron as a high energy, single treatment electro hydraulic device gained FDA approval as the first orthopedic ESWT device for plantar fasciitis and, more recently, for lateral epicondylitis. Two low energy devices have now also gained FDA approval based upon a single treatment. Comparing the acoustic data, differences between the OssaTron and the other devices are obvious and will be elaborated upon. Cluster analysis of the outcomes and the acoustical data are presented and new concepts will be suggested.
Treatment of nonunions of long bone fractures with shock waves
Authors: Wang Ching-Jen
Published: October 2013

A prospective clinical study investigated the effectiveness of shock waves in the treatment of 72 patients with 72 nonunions of long bone fractures (41 femurs, 19 tibias, 7 humeri, 1 radius, 3 ulnas and 1 metatarsal). The doses of shock waves were 6000 impulses at 28 kV for the femur and tibia, 3000 impulses at 28 kV for the humerus, 2000 impulses at 24 kV for the radius and ulna, and 1000 impulses at 20 kV for the metatarsal. The results of treatment were assessed clinically, and fracture healing was assessed with plain x-rays and tomography. The rate of bony union was 40% at 3 months, 60.9% at 6 months and 80% at 12 months followup. Shock wave treatment was most successful in hypertrophic nonunions and nonunions with a defect and was least effective in atrophic nonunions. There were no systemic complications or device-related problems. Local complications included petechiae and hematoma formation that resolved spontaneously. In the author’s experience, the results of the shock wave treatment were similar to the results of surgical treatment for chronic nonunions with no surgical risks. Shock wave treatment is a safe and effective alternative method in the treatment of chronic nonunions of long bones.
Simultaneous measurements of the cavitation and acoustic fields of an electrohydraulic lithotripter
Authors: Chitnis Parag , Van Cauwelaert Javier , Cleveland Robin
Published: October 2013

Simultaneous measurements of the cavitation and acoustic fields were carried out in an electrohydraulic lithotripter. Cavitation was measured with a dual passive cavitation detector (PCD) and acoustic pressure with a fiber optic probe hydrophone. The devices were positioned so that they measured the same volume of space. Measurements were acquired at various locations in the field of the lithotripter. The characteristic time (t—c) was used as a parameter for quantifying the strength of cavitation activity. At the focus we found a linear correlation between the peak negative pressure (P−) of the SW and t—c as well as between the area under the negative tail and t—c. The maximum t—c was found to be 500 μs at P− of 10 MPa and the minimum value of t—c was 200 μs at P− of 5 MPa. An acoustic signal produced due to the collapse of cavitating bubbles was also detected by the hydrophone and was consistent with the collapse signal measured by the PCD. [Work supported by NIH.]
Overview of biological-barrier permeabilization with ultrasound
Authors: Mourad Pierre D.
Published: October 2013

This talk contains an overview of how ultrasound has been used to permeabilize various biological barriers, quoting liberally and with citation the work of others (with some contribution from the present author). These barriers include skin, blood clots, cell membranes, and the blood–brain barrier. In all cases I will try to review the mechanisms by which ultrasound achieves biological barrier permeabilization, although typically the main mechanism is cavitation.
Acoustic transients from subsonic high-speed sources using a linear time-varying systems approach
Authors: Stepanishen Peter R. , Hu James , Kuklinski Robert
Published: October 2013

Several approaches are available to investigate acoustic transient radiation from high-speed subsonic moving multipole sources in a free field. A new impulse response approach will be presented to address the problem for sources in a free field and ducted environments. In contrast to the case of a fixed source which leads to a convolution integral representation for the field, the new approach leads to an integral representation in which the kernel is related to the impulse responses for stationary sources along the path of the source. A brief physically motivated development of the approach will be first presented and then the approach will be used to address several acoustic transient radiation problems of interest. As a baseline for comparison numerical results will be first presented to demonstrate the well known Doppler effects for moving harmonic sources in a free field environment and an unbounded half space. Numerical results will then be presented to illustrate the additional complexity of the transient field for moving sources in an acoustic waveguide representing a long test acoustic test tank. [Work supported by ONR.]
Application of multibeam sonar in marine ecology and fisheries research: New fields and limitations
Authors: Gerlotto Francois M. , Brehmer Patrice A. , Fernandes Paul G. , Reid David G. , Copland Philip , Georgakarakos Stratis , Paramo Jorge
Published: October 2013

Multibeam sonars have been used since the mid 90s for three dimensions and a dynamic observation of fish schools and shoals in their environment. A 455 kHz Reson Seabat 6012, with 60 beams of 1.5×22 deg, was used. It has allowed the quantification of school avoidance in acoustic surveys; the three-dimensional description of school structure and position in the water column; the noninvasive study of the real schooling behavior of fish in the wild; the observation and quantification of fish in relation to survey gear; and the predation on mussels in aquaculture by fish schools; the fish school distribution in relation to ecological factors, even in very shallow water. These observations showed that a multibeam sonar can be a useful tool for improving the quality of stock assessment surveys and studying the behavioral ecology of important commercial species. To date all these applications are essentially observational. The next stage in the development of these systems will be to produce quantitative biomass estimates. To achieve this, calibration systems and side aspect TS measurements for the fish will be required. The paper presents the current uses of this instrument described above, and discuss the research requirements for use in fisheries science.
Predicting speech intelligibility in noise for hearing-critical jobs
Authors: Soli Sigfrid D. , Laroche Chantal , Giguere Christian
Published: October 2013

Many jobs require auditory abilities such as speech communication, sound localization, and sound detection. An employee for whom these abilities are impaired may constitute a safety risk for himself or herself, for fellow workers, and possibly for the general public. A number of methods have been used to predict these abilities from diagnostic measures of hearing (e.g., the pure-tone audiogram); however, these methods have not proved to be sufficiently accurate for predicting performance in the noise environments where hearing-critical jobs are performed. We have taken an alternative and potentially more accurate approach. A direct measure of speech intelligibility in noise, the Hearing in Noise Test (HINT), is instead used to screen individuals. The screening criteria are validated by establishing the empirical relationship between the HINT score and the auditory abilities of the individual, as measured in laboratory recreations of real-world workplace noise environments. The psychometric properties of the HINT enable screening of individuals with an acceptable amount of error. In this presentation, we will describe the predictive model and report the results of field measurements and laboratory studies used to provide empirical validation of the model. [Work supported by Fisheries and Oceans Canada.]
Analysis of practical sound transmission class (STC) measurements performed under a variety of field conditions
Authors: Conroy James
Published: October 2013

Sound transmission class (STC) measurements were made using a simplified version of the procedure presented in ASTM E336-96 and the results compared to STC values found in the literature. STC is used to provide a single number speech privacy rating for a building partition. It is calculated by measuring the transmission loss of a partition and applying a curve fitting procedure. While the standards provide a highly detailed data collection and processing procedure, they give limited insight into the type of response and deviation that might be expected from measurements made along a partition or when comparing results from similar partitions under different field conditions. Likewise, while there is discussion in the literature on STC, with some attempt to relate values to human perception and provide ratings for common partitions there is a generally limited discussion involving data collected under real conditions. The partitions in three different office rooms were tested and the results described. In particular, the effect of speaker type and location, source type, room geometry, microphone placement, the spatial variation and repeatability of measurements on a particular partition, and a comparison of results from similar partitions under different field conditions were analyzed and discussed in detail.
Development of a fresh-water tank facility for calibrating multibeam sonar
Authors: Baldwin Kenneth C. , Mayer Larry , McLeod Andrew , Foote Kenneth G. , Chu Dezhang , Beaudoin Jonathan , Weber Tom
Published: October 2013

Multibeam sonars are being used increasingly to image fish. To realize their quantitative potential for measuring the numerical density of fish and other aquatic organisms, it is essential that they be calibrated. This can be done by the use of standard targets or reference hydrophones. The calibration of narrow beam acoustic arrays requires precision angular positioning of the transducer under test. This precision is defined as 0.1 deg of angular position control. This degree of control is achievable with the use of a precision rotary table typically used in CNC machining. This presentation describes: system specifications and the LabView program used to control and coordinate position and acoustic data acquisition, the initial evaluation of the rotary table for repeatability and possible backlash, and representative acoustic measurements made with multibeam sonars using the new system. [Work supported by NSF Contract No. OCE 0002842.]
Acoustics and vibration animations: A surprisingly successful website
Authors: Russell Daniel
Published: October 2013

For the past 8 years the author has been creating mathematically and physically correct computer animations for use in teaching acoustics to advanced undergraduate engineering and science majors [D. Russell, J. Acoust. Soc. Am. 106, 2197 (1999)]. Compiling these animations, along with supporting text, on a web site (http://www.kettering.edu/∼drussell/demos.html) has resulted in a surprising response from students, teachers, and professionals who have found the animations useful for their own presentations, study, or courses. Unsolicited recognition in the form of web awards and coverage in magazines adds weight to the usefulness of well-made animations for conveying difficult concepts to a wide audience. This presentation will showcase as many of the animations as possible, especially newer ones, including: oscillation, wave superposition, reflection and refraction, particle motion for various wave types, radiation from simple and complex sources, room modes, waves on strings and membranes, bending waves and boundary conditions, and the vibration of guitars and baseball bats. If time permits, some of the methods used to create the animations will be shared.
ASA Education in Acoustics website as new portal
Authors: Everbach E. Carr
Published: October 2013

The ad-hoc On Line Education Committee of the Acoustical Society of America was charged in 2002 with revitalizing the Education in Acoustics website. A web portal, demonstrated at the Nashville, TN, meeting in April, 2003, consists of a fanciful view of Lord Rayleigh’s drawing room. Items within the room are ‘‘hot’’ and lead the visitor to web links whose content is related to the technical committee areas and other areas of interest. The links are configurable via a web (MySQL) database interface so that they can be manipulated without programming. Current efforts include populating the portal with links and adding active content in topic areas that need to be strengthened.
Multistatic broadband sonar (MSBA): Principles and measurements
Authors: Carey William M. , Cable Peter G.
Published: October 2013

Shallow-water (SW) coastal areas with depths between 40 and 200 m with bottom sediment layers (<25 m) formed by deposition and sea level variations are known to have frequency-dependent sound transmission and reverberation characteristics especially under the adverse conditions of downward refraction. Coastal ocean-dynamics complicates these environments by coupling the surface, volume, and bottom characteristics and can dramatically affect the temporal and spatial coherency of the signal. The broad-band signal and processing smear these frequency-dependent effects as well as signal excess fluctuations. Furthermore, recent experiments have shown that despite these complexities, explosive sources coupled with directional receivers have the capability to detect, localize, and classify sonar targets in the presence of clutter most likely due to bottom features, fish schools, and sunken objects. Active search sonar operations in SW are typically reverberation limited and experiments have shown that MSBA sonar when employed in bistatic source-receiver geometries can be effective. This paper reviews the principles underlying the MSBA sonar in shallow water and presents results from several experiments that demonstrated the utility of MSBA. The results are discussed in terms of a classical sonar model with basic statistical considerations to define limits on the detection, classification, and localization with multiple receivers.
A survey of the acoustical quality of seventeen libraries at Princeton University
Authors: Markham Benjamin
Published: October 2013

The purpose of this study was to identify objective acoustic measures that correlate with the subjective responses of students and administrators to libraries at Princeton University. The motivation for this study was to determine what is necessary in order to provide a comfortable acoustic environment for users of a new science library to be built on campus. On 31 March 2003, Acentech, Incorporated evaluated 17 library spaces and interviewed a number of students and librarians at Princeton. Based on the results of the survey, the author proposes that a comfortable acoustic environment in a library is an environment that provides freedom from distraction; in other words, casual conversation and other noises in the library will not distract users reading or studying in the library. In order to provide such an environment, a library must have (1) appropriate levels of background sound, (2) a physical barrier between noise-producing and noise-sensitive sections, and (3) sufficient sound absorbing material in the space. Measured quantitative metrics support these conclusions.
A global survey of the distribution of free gas in marine sediments
Authors: Fleischer Peter , Orsi Tim , Richardson Michael
Published: October 2013

Following the work of Aubrey Anderson in the Gulf of Mexico, we have attempted to quantify the global distribution of free gas in shallow marine sediments, and have identified and indexed over one hundred documented cases in the scientific and engineering literature. Our survey confirms previous assumptions, primarily that gas bubbles are ubiquitous in the organic-rich muds of coastal waters and shallow adjacent seas. Acoustic turbidity as recorded during seismo-acoustic surveys is the most frequently cited evidence used to infer the presence of seafloor gas. Biogenic methane predominates within these shallow subbottom deposits. The survey also reveals significant imbalances in the geographic distribution of studies, which might be addressed in the future by accessing proprietary data or local studies with limited distribution. Because of their global prevalence, growing interest in gassy marine sediments is understandable as their presence has profound scientific, engineering and environmental implications.
An interfacial rheological model of ultrasound contrast agents: Theory and experiments
Authors: Sarkar Kausik , Chatterjee Dhiman , Shi William T. , Forsberg Flemming
Published: October 2013

A new interface model with zero thickness and intrinsic surface rheological parameters has been developed for the encapsulation of a microbubble contrast agent. A modified Rayleigh–Plesset equation with these parameters (surface tension γ and surface dilatational viscosity κs) was obtained. The rationale for the zero-thickness interface lies in the anisotropy and the inhomogeneity in the structure of the encapsulation. The parameters of the model were determined using in vitro attenuation data for various contrast agents (Albunex, Optison, Sonazoid, and Quantison). The linearized dynamics was used to match data from a controlled set of experiments performed at smaller pressure amplitudes (<0.1 MPa). The model was investigated for its ability to predict the nonlinear response at higher amplitudes (>1.0 MPa) for two test cases: Optison (Mallinckrodt, St. Louis, MO) with γ=0.9 N/m, κs=0.08 msP and Sonazoid (Amersham Health, Oslo, Norway) with γ=0.6 N/m, κs=0.01 msP. In contrast to existing models, the new model captured the distinct characteristics of subharmonic emissions—initiation and rapid growth—for these agents. The present model seems to be a reliable descriptor of contrast agent behaviors, and therefore, may be used to characterize different agents and to design next generation agents by tuning the model parameters. [Work supported by DOD.]
The comb waveform as an efficient method for wideband measurements
Authors: Boober Walter H. , Lau Gorham , Benjamin Kim C. , Walsh Kenneth M.
Published: October 2013

An efficient acoustic calibration technique based on a uniformly-weighted comb waveform is presented. The method takes advantage of the linear, time invariant nature of the measurement configuration and the comb’s wide bandwidth to capture all spectral components of interest for a device under test in a single ping. Results comparing single ping comb measurements with conventionally obtained CW measurements are presented. The examples given illustrate the accuracy and utility of this technique for the calibration of broadband systems.
In situ calibration of sonar arrays
Authors: Luker L. D. , Forsythe S. E.
Published: October 2013

The transmitting and receiving properties of the channels of sonar arrays can change with time resulting in a degradation of the array’s performance. Fortunately, the degradation in performance can be minimized, perhaps even eliminated, if the changes in a channel’s transmitting or receiving properties are compensated for in the array’s beamformer electronics. However, this requires up-to-date knowledge of the acoustic performance of each of the array’s channels. This paper describes a procedure for the in situ calibration of sonar arrays when the vessel they are installed on is in open water. It can be used to determine changes in the electroacoustic performance of the projecting and receiving channels of the array. The method used is based on a procedure for in situ comparison calibration of transducers [A. L. Van Buren, ‘‘Procedure for the in situ calibration of sonar transducers,’’ J. Acoust. Soc. Am. 90, 48–52 (1991)] that uses sound-propagation factors measured when the vessel is first deployed to account for the influence of the vessel’s structure. Results are presented that show comparisons of the measured degradation of numerous channels in a planar array using an independent acoustic measurement and the in situ method. [Work supported by ONR.]