bluuebunny/crossref_metadata_2025 huggingface dataset:
The difference between a question and a statement: A cross-dialect survey
Authors: Kochanski Greg , Grabe Esther , Coleman John
Published: September 2013

Seven British English dialects were studied to see what prosodic distinctions are made between statements and questions in read speech. A set of Bayesian classifiers was built upon feature vectors obtained from a spectral analysis of measures of (1) f0, (2) loudness, (3) spectral slope and (4) voicing periodicity. It was found that the prosodic information useful for the question/statement distinction is distributed broadly across the utterance, and that loudness and spectral slope can be nearly as informative as f0 (voicing is less informative). The three important acoustic features carry somewhat less than one bit of information each, so prosodic information could be valuable to the listener, and the listener may be able to make the question/statement decision early in the utterance. The contrast differs from one acoustic property to the next: f0 is marked primarily by slow variations. Conversely, the spectral slope and loudness measurements primarily use shorter-wavelength features, corresponding to structures that are a syllable or two long. We also find substantial differences in the prosodic information that different dialects use, and substantial differences between speakers of the same dialect. [Research supported by the UK Economic and Social Research Council, Grant RES 00-23-1049.]
An experimental verification of the spherical wave effect in unconsolidated sediments
Authors: Camin H. John , Isakson Marcia
Published: September 2013

Several research institutions are investigating models to properly describe high-frequency acoustic properties of unconsolidated sediments. This talk will focus on comparing experimental reflection coefficient measurements over a range of frequency (30–160 kHz) and angle to five of these theoretical sediment models: the fluid/fluid model, the visco-elastic model, the effective density fluid model (EDFM), Buckingham’s micro-sliding model, and the Biot/Stoll poro-elastic model. Since spherical transducers were used in the experiment, spherical wave effects will be added to the models using a plane-wave decomposition method. A common set of parameters will be used in all models. Fluid and visco-elastic model parameters have been measured and verified at the test location. The Biot parameters were determined from measured values and previous inversions of plane-wave reflection data taken at the same location. Air/water interface data will be measured and computed for each model as a test case. [Work supported by ONR, Ocean Acoustics.]
Approximate single wave equation derived from Biot’s porous media equations
Authors: Pierce Allan D. , Carey William M. , Lynch James F. , Zampolli Mario
Published: September 2013

Manipulation of Biot’s equations using low-frequency and long-wavelength approximations yields wave equation with a dissipation term that predicts plane wave attenuation coefficients proportional to the square of the frequency. Examination of Biot’s original derivation verifies that the wave speed in this equation is what results from Wood’s theory. The derivation predicts that the fluid displacement is a predictable fraction of that of the solid matrix, and this is consistent with the behavior in Brillouin’s model of an elastic spring loaded with masses of alternating magnitude. Biot’s assumption that the pores must be connected is argued to be unnecessary. Unconnected pores may be elongated with constrictions, and the sound field will cause some portions of the porelets to be compressed more than other portions, so that pressure differences across constrictions force viscous flow. A heuristic derivation shows that the wave attenuation coefficient is inversely proportional to viscosity and sound speed, and directly proportional to density, the number of porelets per unit volume, the average length of porelets, and the square of the cross-sectional area of the constrictions and frequency. The heuristic theory is supported with a detailed analysis of the energy dissipation within a dumbbell-shaped porelet within an extended isotropic elastic solid.
In situ measurement of sediment acoustic properties and relationship to multibeam backscatter
Authors: Kraft Barbara J. , Fonseca Luciano , Mayer Larry A. , McGillicuddy Glenn , Ressler Jason , Henderson Jennifer , Simpkin Peter G.
Published: September 2013

In support of the Office of Naval Research’s Geoclutter Program, in situ acoustic and resistivity measurements were obtained using ISSAP, a device developed and built by the Center for Coastal and Ocean Mapping. The primary focus of this research is to understand the relationship between remotely measured backscatter and the acoustic properties of surficial sediments. The field area selected was Portsmouth Harbor (NH) due to the comprehensive sonar data set collected during the Shallow Water Survey 2001 conference. Seawater and surficial sediment measurements of compressional wave sound speed, attenuation, and resistivity were obtained at a large number of stations selected to represent a range of seafloor backscatter types. The ISSAP platform was configured with two orthogonal matched pairs of transducer probes operating at frequencies of 47 and 65 kHz. A Van Veen grab sampler was also used to obtain a sediment sample at each station. Subsampling tubes were used to obtain undisturbed samples; laboratory measurements of density, compressional wave speed and attenuation, resistivity, and grain size were completed. For a small subset of samples, selected to represent a range of sediment types, measurements of permeability, shear wave speed, and attenuation were completed. [Research supported by ONR Grant No. N00014-00-1-0821.]
Basic research on auditory-visual interaction and listening in rooms
Authors: Wightman Frederic L. , Zahorik Pavel A.
Published: September 2013

Attending a live concert is a multisensory experience. In some cases it could be argued that hearing is the primary sense involved, but it is never the only one. Vision, smell, and even touch make important contributions to the overall experience. Moreover, the senses interact such that what one hears, for example, is influenced by what one sees, and vice-versa. This talk will address primarily the auditory aspects of the concert experience, focusing on the results of basic studies of human spatial hearing in reverberant environments, and how these results may help us understand the concert experience. The topics will include sound localization in anechoic and reverberant environments, the precedence effect, the cocktail party effect, the perception of distance, and the impact of room acoustics on loudness perception. Also discussed will be what has been learned from empirical research on auditory-visual interactions. In this area the focus will be on the visual capture effects, the best known of which is the ventriloquism effect. Finally, the limitations of modern psychoacoustics will be addressed in connection with the problem of fully revealing the complexities of the concert experience, especially individual differences in subjective impression.
Neural mechanisms underlying the analysis of sonar and social vocalizations: Spectral and temporal integration in the mustached bat
Authors: Wenstrup Jeffrey J. , Nataraj Kiran , Gans Don , Sheykholeslami Kianoush
Published: September 2013

The analysis of sonar echoes by the mustached bat depends on combination-sensitive neurons that respond best when distinct spectral elements of a sonar pulse and echo occur in a particular temporal relationship. Such integrative response properties underlie direct comparisons of acoustic features in outgoing pulses and returning echoes, comparisons thought to encode pulse–echo delay and other information-bearing features of echoes. These response properties are abundant in the auditory midbrain, thalamus, and cortex of the mustached bat. Combination-sensitive neurons utilize facilitatory and inhibitory neural interactions to create selective responses to acoustic features. The different interactions (facilitatory and inhibitory) originate in different stages within the ascending auditory pathway. Inhibitory interactions arise mostly in the auditory brainstem. Facilitatory interactions arise within the inferior colliculus, but also display the results of the inhibitory interactions originating at brainstem levels. These response properties are well suited to the analysis of sonar echoes, but similar combinatorial response properties are tuned to spectral elements outside sonar frequency bands, probably to elements of social vocalizations. It is therefore likely that the neural analysis of biosonar signals shares common features with the analysis of other vocal signals. [Work supported by the National Institute on Deafness and Other Communication Disorders.]
Pinniped bioacoustics: Atmospheric and hydrospheric signal production, reception, and function
Authors: Schusterman Ronald J. , Kastak David , Reichmuth Kastak Colleen , Holt Marla , Southall Brandon L.
Published: September 2013

There is no convincing evidence that any of the 33 pinniped species evolved acoustic specializations for echolocation. However, all species produce and localize signals amphibiously in different communicative contexts. In the setting of sexual selection, aquatic mating male phocids and walruses tend to emit underwater calls, while male otariids and phocids that breed terrestrially emit airborne calls. Signature vocalizations are widespread among pinnipeds. There is evidence that males use signature threat calls, and it is possible that vocal recognition may be used by territorial males to form categories consisting of neighbors and strangers. In terms of mother–offspring recognition, both otariid females and their pups use acoustical cues for mutual recognition. In contrast, reunions between phocid females and their dependent pups depend mostly on pup vocalizations. In terms of signal reception, audiometric studies show that otariids are highly sensitive to aerial sounds but slightly less sensitive to underwater sounds. Conversely, except for deep-diving elephant seals, phocids are quite sensitive to acoustic signals both in air and under water. Finally, despite differences in absolute hearing sensitivity, pinnipeds have similar masked hearing capabilities in both media, supporting the notion that cochlear mechanics determine the effects of noise on hearing.
Human listening studies reveal insights into object features extracted by echolocating dolphins
Authors: DeLong Caroline M. , Au Whitlow W. L. , Roitblat Herbert L.
Published: September 2013

Echolocating dolphins extract object feature information from the acoustic parameters of object echoes. However, little is known about which object features are salient to dolphins or how they extract those features. To gain insight into how dolphins might be extracting feature information, human listeners were presented with echoes from objects used in a dolphin echoic-visual cross-modal matching task. Human participants performed a task similar to the one the dolphin had performed; however, echoic samples consisting of 23-echo trains were presented via headphones. The participants listened to the echoic sample and then visually selected the correct object from among three alternatives. The participants performed as well as or better than the dolphin (M=88.0% correct), and reported using a combination of acoustic cues to extract object features (e.g., loudness, pitch, timbre). Participants frequently reported using the pattern of aural changes in the echoes across the echo train to identify the shape and structure of the objects (e.g., peaks in loudness or pitch). It is likely that dolphins also attend to the pattern of changes across echoes as objects are echolocated from different angles.
Biosonar performance of foraging Blainvilles beaked whales (Mesoplodon densirostris)
Authors: Madsen Peter T. , Johnson Mark , Tyack Peter L. , Aguilar de Soto Natacha , Zimmer Walter M. X.
Published: September 2013

Echolocating animals like bats and toothed whales navigate and locate food by means of echoes from sounds transmitted by the animals themselves. Toothed whale echolocation has been studied intensively in captivity, but little information exists on how echolocation is used by wild animals for orientation and prey location. To expand on this issue, a noninvasive, acoustic Dtag (96-kHz sampling, 16-bit resolution) was deployed on two Blainvilles beaked whales. The tagged whales only clicked at depths below 200 m during deep foraging dives. The echolocation clicks are directional, 250-ms transients with peak energy in the 30–40-kHz band. Echoes from the seafloor and from prey items were recorded. The regular click rate is not adjusted to the decreasing echo delay from incoming prey until the target is within an approximate body length of the whale after which the click rate is increased rapidly akin to the buzz phase of echolocating bats. This suggests that the whales use different sonar strategies for operating in near versus far field modes. Changes in received echo intensities from prey targets during approaches are compared to the active gain control in the receiving system of bats and in the transmitting system of dolphins.
A computational model of echolocation: Transformation of spectrogram into the reflected intensity distribution for range discrimination of multiple closely spaced objects
Authors: Matsuo Ikuo , Kunugiyama Kenji , Yano Masafumi
Published: September 2013

Using frequency-modulated echolocation, bats can discriminate the range of objects with an accuracy of less than a millimeter. However, the echolocation mechanism is not well understood. The delay separation of three or more closely spaced objects can be determined through analysis of the echo spectrum. However, delay times cannot be properly correlated with objects using only the echo spectrum because the sequence of delay separations cannot be determined without information on temporal changes in the interference pattern of the echoes. To illustrate this, Gaussian chirplets with a carrier frequency compatible with bat emission sweep rates were used. The delay time for object 1, T1, can be estimated from the echo spectrum around the onset time. The delay time for object 2 is obtained by adding T1 to the delay separation between objects 1 and 2 (extracted from the first appearance of interference effects). Further objects can be located in sequence by this same procedure. This model can determine delay times for multiple closely spaced objects with an accuracy of about 1 microsecond, when all the objects are located within 30 microseconds of delay separation. This accuracy is possible even with objects having different reflected intensities and in a noisy environment.
Geoacoustic inversion of broad-band ambient noise data using undersampled and short aperture arrays
Authors: Siderius Martin , Porter Michael , Harrison Chris
Published: September 2013

Ocean ambient noise is generated in many ways such as from winds, rain and shipping. A technique has recently been developed [Harrison and Simons, J. Acoust. Soc. Am. 112 (2002)] that uses the vertical directionality of ambient noise to determine seabed properties. The ratio of beams steered towards the surface to those steered towards the bottom produces the bottom reflection loss curve. This technique was applied to data in the 200–1500-Hz band using a 16-m array. Extending this to higher frequencies allows the array length to be substantially shortened and greatly reduces interference from shipping. However, this limits the low end of the frequency spectrum since reduced aperture increases beam widths and the up/down beam ratio no longer produces reflection loss. Similarly, for high frequencies, if hydrophone spacing is greater than half-wavelength, the beamformed output is aliased and again the up/down ratio produces erroneous results. In general, frequencies much below the array design will suffer from large beams and frequencies above from undersampling. In this paper, we describe techniques for obtaining seabed properties from ambient noise measured on short or undersampled arrays. Results will be presented from the KauaiEx (July 2003) and ElbaEx (October 2003) experiments.
Geoacoustic inversion from moving ship of opportunity in deep-water environment
Authors: Knobles David P. , Scoggins Tim , Shooter Jack
Published: September 2013

This study examines the estimation of seabed geoacoustic parameters in a deep-water environment using acoustic data generated from the noise of a moving surface ship. The received sound field was recorded on a vertical line array in the North Pacific in approximately 5000 m of water. These data, which were recorded in 1973 in an experiment called Church Opal, have recently been re-digitized and made available to the underwater acoustics community. Spectrograms of time and frequency for hydrophones below the critical depth illustrate striation patterns associated with the inverse of the time interval between direct and bottom reflected rays paths. The cross-correlation of signals between phones on the VLA is thus sensitive to the structure of the seabed. A cost function of the difference between cross-phone spectra of modeled and measured received acoustic signals in the 10–600-Hz band is minimized using a simulated annealing method. Parameters that are estimated include those associated with the ship track and those associated with the seabed. Uncertainties of the various parameters are examined to determine the uniqueness of the various parameters estimated from the acoustic data. The estimated geoacoustic structure is compared to that reported in the literature. [Work supported by ONR.]
Iterative geoacoustic inversion
Authors: Gerstoft Peter , Huang Chen-Fen , Hodgkiss William S.
Published: September 2013

In geoacoustic inversion we commonly invert each data block independently. But when these inversions are close in space and time it is often beneficial to use the results of the previous inversion as a starting condition for the next inversion. A natural framework for this is a Bayesian approach where the posterior inversion becomes the prior for the current inversion. It is implemented using a Metropolis–Hastings sampler. Such an approach potentially will allow us to work with lower SNR ratios, as in for example self-noise inversion. This approach has similarities to data assimilation and could lead to nowcasting of the acoustic field. [Work supported by ONR.]
Data error estimation for matched-field geoacoustic inversion
Authors: Wilmut Michael J. , Dosso Stan E. , Dettmer Jan
Published: September 2013

Nonlinear Bayesian methods have been applied to geoacoustic inversion to estimate uncertainties for seabed parameters by sampling the posterior probability density. This procedure requires quantifying the errors on the acoustic data, including both measurement and theory errors, which are generally not well known. To date, point estimates for data errors have been derived using a global maximum likelihood approach. However, this is not consistent with the Bayesian formulation, and ignores the effects of uncertainty in the error estimates and interdependencies between the data errors and geoacoustic parameters. The Bayesian approach treats the data errors as random variables and includes them as additional parameters within the inversion. However, this increases significantly the number of unknowns and the computational effort. A third approach is to use a local maximum likelihood error estimate evaluated independently for each geoacoustic model considered in the sampling procedure. This has the benefit of not increasing the number of unknowns or computational effort, but includes some of the effects of the error uncertainties and interdependencies. The three approaches are compared for Bayesian matched-field geoacoustic inversion of both synthetic and experimental data.
Novel ultrasonic methods of imaging interstitially implanted brachytherapy seeds
Authors: Feleppa Ernest J. , Alam S. Kaisar , Ketterling Jeffrey , Kalisz Andrew , Ramachandran Sarayu , Lizzi Frederic L.
Published: September 2013

Interstitially implanted radioactive seeds are becoming a popular and effective means of treating a wide range of diseases, primarily cancer. Brachytherapy of prostate cancer, for example, is proving to be as effective, in terms of 5-year survival, as surgery for management of gland-confined disease, and to many, the side effects of brachytherapy are less debilitating than those of surgery. While seeds are implanted under guidance from transrectal ultrasound, gland movement and distortion during implantation may lead to seed misplacement; implanted seeds are difficult to visualize ultrasonically after implantation for a variety of reasons. We are investigating a variety of ultrasonic techniques intended to overcome the limitations of conventional ultrasonic imaging, and the following three methods are showing encouraging promise: resonance/vibration imaging; modified elastography; and two-dimensional correlation. The resonance/vibration method induces natural vibrations in seeds and, using power-Doppler methods, images the movement these vibrations induce in immediately adjacent tissues. The modified-elastography method uses standard elastographic processing with higher-than-normal applied strains so that soft-tissue signals decorrelate while echo signals from rigid seeds retain correlation. The two-dimensional correlation method compares echo signals from tissue with those from a reference seed and shows seed locations by mapping the resulting correlation coefficients.
Thermal ablation monitoring using radiation force-induced steady-state tissue motion
Authors: Wang Hesheng , Zhou Yun , Deng Cheri
Published: September 2013

High-intensity focused ultrasound (HIFU) increases temperature in tissue and also induces local tissue movement during HIFU ablation. Such induced motion can be exploited to detect changes in tissue stiffness to monitor HIFU treatment. To implement real-time HIFU treatment monitoring, a HIFU duration is segmented into a sequence of on and off periods. The off periods are required for unaffected interrogation and are sufficiently short to minimize interruption to the intended thermal treatment. It is demonstrated that the displacements generated during the relatively long on period reach steady state and undergo recovery during the next off period. Our study focuses on the investigation of the steady-state displacement and its recovery to detect changes in tissue elasticity without additional push pulses during an HIFU treatment exposure. An integrated model and finite difference algorithm are developed to study how the dynamic displacements are related to HIFU characteristics and tissue properties. Our experiments utilized an ultrasound imaging system. The induced displacement and its recovery are estimated from the acquired backscattered signals using a cross-correlation algorithm. Optimal HIFU on and off periods are investigated. Our results indicate that the steady-state displacements characterize the changes in tissue elasticity accompanying lesion formation during HIFU ablation.
Palpation strategies using the acoustic radiation force: A vectorial analysis
Authors: Bercoff Jeremy , Tanter Mickael , Fink Mathias
Published: September 2013

Using ultrasound focused beams, mechanical sources radiating low-frequency shear waves can be generated inside the body. Such waves propagate inside tissues at a few m/s and are sensitive to the mechanical properties of soft tissues. The ultrafast scanner developed at our laboratory (5000 images/s) is able to generate shear sources and image, in real time, the propagation of the resulting shear waves. Pushing and imaging sequences can be interleaved as desired. This great versatility enables various strategies concerning the pushing sequence. In particular, the supersonic regime, which consists of moving the shear source at a speed higher than shear wave speed, has been introduced in previous works. In this work, a detailed vectorial analysis of the supersonic regime is presented using a 3D Green’s function formalism. By varying the speed and the trajectory of the shear source, conical waves of different angles, curved waves, or focused waves can be generated. Furthermore, changing the amplitude of the pushing sequences allows the temporal modulation of the resulting shear waves, leading to a complete control of the spatio-temporal shape of the shear wave. These palpation strategies are carefully studied using numerical simulations and tested on tissue-mimicking phantoms.
Noninvasive evaluation of complex elastic modulus of arterial vessels by ultrasound
Authors: Zhang Xiaoming , Fatemi Mostafa , Greenleaf James F.
Published: September 2013

Pulse wave velocity (PWV) is widely used for estimating the stiffness of an artery. It is well known that a stiffened artery can be associated with disease and aging. Usually, PWV is measured using the foot-to-foot time-delay method. However, the foot of the pulse wave cannot be accurately determined due to reflected waves. In addition, PWV is an average indicator of artery stiffness between the two measuring points. We propose to generate a wave in the artery wall using localized ultrasound radiation force. The wave velocity can be measured accurately by the phase change versus distance over a few millimeters. A mathematical model is developed by which the real part of the complex Young’s modulus of the artery can be determined from measured wave velocities. The imaginary part of the complex modulus can be assessed by the wave amplitude decay over distance. Experiments were conducted on a pig carotid artery in gelatin. The measured wave velocity is about 3 m/s at 100 Hz and 6.5 m/s at 500 Hz. The real part of complex modulus is estimated to be 300 kPa. The present technique offers a new method for estimating the complex elastic modulus of the artery over a short length.
Improvement in elastographic signal-to-noise ratio and resolution using coded excitation in elastography
Authors: Souchon Remi , Bera Jean-Christophe , Pousse Agnes , Chapelon Jean-Yves
Published: September 2013

Coded excitation has been used in conventional sonography to improve the sonographic signal-to-noise ratio independently of resolution. In elastography, a tradeoff exists between spatial resolution and the elastographic signal-to-noise ratio (SNRe). In the present work, the use of coded excitation was investigated to remove this ambiguity in elastography. Both numerical simulations and phantom experiments were carried out to estimate the SNRe in a homogeneous material and the resolution in a material containing calibrated inclusions. These results were compared with those obtained using conventional pulse excitation. Various codes (Golay, Barker, chirp) and code lengths were tested. The numerical simulations used a simple 1D backscattering model to show the theoretical effects of coded excitation. Experiments were carried out using a more realistic setup based on a sector-scan imaging probe. In the absence of sonographic noise, simulations showed that codes induced only a slight decrease in SNRe at no cost in resolution. When sonographic noise was added into the model, a large improvement in SNRe was obtained at constant resolution. The experimental results corroborated these findings. [Work supported in part by National Cancer Institute (USA) Program Project Grant P01-CA64597.]
Automatic error correction in quantitative elasticity imaging
Authors: Barbone Paul E.
Published: September 2013

We consider the inverse problem associated with imaging the elastic shear modulus of soft tissue. We work from the premise that tissue deformation resulting from external forces has been imaged by ultrasound. From this measured deformation, an assumed form of the tissue’s constitutive equation (e.g., linear elastic), and the law of conservation of momentum we arrive at the inverse problem. We present mathematical results that show how many data are required to reliably reconstruct the shear modulus. Further, we present a consistency condition that must be satisfied by the measured deformation field, provided that the tissue obeys the laws of linear elasticity. From this consistency condition, we show how to identify the existence of errors in data. These can then be corrected, under the assumption that the measured deformation field is close to the actual field. We present several computed examples. [Work supported by NSF via CenSSIS ERC.]
Road traffic noise impact assessment based on the difference between existing and future traffic noise levels
Authors: Balachandran Chetlur G. , Juhasz Sandor , Morrone Arthur , Castillo Noemi
Published: September 2013

New York City has established standards for impact assessment based on the difference in traffic noise levels between the existing and future conditions. This difference is directly related to the logarithmic ratio of passenger car equivalents under the two conditions. The FHWA Traffic Noise Model 2.0 predicts noise levels from data based on the number of vehicles classified by category, average vehicle speed, and the distance to receptor. The model results can be used to determine the change in noise level between the existing and future conditions. Both approaches give essentially the same result. In heavily populated urban centers like New York City, where the measured baseline existing noise is not only from road traffic but also from many other noise sources such as air-conditioning units, people noise, construction activities, etc., a new approach is needed to determine the change between the existing and future noise levels. This approach utilizes data obtained from field noise measurements which are conducted with and without trucks. This realistic procedure can be used to determine the number of new heavy trucks that could be introduced into the existing traffic stream without exceeding impact thresholds set by the New York City Noise Regulations.
Determination of sound power levels of some pyrotechnic devices using sound pressure measurements
Authors: Wu Weixiong
Published: September 2013

A noise measurement study was conducted at five reservoirs in New York State during the winter and summer of 2003 to determine the sound power levels generated by some specific pyrotechnic devices (bangers, screamers, and CAPAs) using sound pressure techniques. The study was performed in support of an environmental impact statement (EIS) that defined the areas around each of these reservoirs where any significant impacts would occur as a result of the pyrotechnic operations. Sound characteristic data for each pyrotechnic device was collected at short distances with a direct line of sight to the pyrotechnic sources. The sound pressure levels for each pyrotechnic device were measured in two conditions (winter and summer) to examine the accuracy of measured data. The sound power levels, including both A-weighted and C-weighted 1/1 octave band values, were calculated based upon the measured sound pressure levels. With the absence of literature and manufacturing data supports, the values of this study were believed to be the most comprehensive emission data for the EIS noise analysis.
Environmental noise impact of modern wind farms
Authors: Piacsek Andrew , Wagner Greg
Published: September 2013

Electric power production from wind turbines has increased substantially during the past few years due to the growing emphasis on renewable energy sources and more efficient wind turbine technology. Although modern turbines are significantly quieter than early models, wind farms that are proposed near residential areas generate concern about potential noise issues. The present study consists of two parts: (1) the measurement of sound levels within a 2-km radius of the existing Nine Canyons wind farm near Richland, WA, and (2) the application of an outdoor sound propagation model to predict noise levels, both at Nine Canyons and in the vicinity of a proposed farm near Ellensburg, WA. At most locations within the Nine Canyon site, recorded sound levels were less than predicted levels, with the exception of some downwind sites that were lower in elevation than the source. Noise levels were greatest downwind from the turbines, but never exceeded 50 dBA beyond 500 m from the nearest turbine. In many cases, wind noise at the microphone exceeded noise levels from the turbines.
Recent developments in laser Doppler velocimeter for landmine detection
Authors: Lal Amit , Aranchuk Vyacheslav , Hess Cecil
Published: September 2013

This presentation discusses laser Doppler vibrometer (LDV) instruments developed by MetroLaser that are specifically tailored to work with the acoustic/seismic technique for buried landmine detection and data obtained with these systems under various field conditions. The first system is a simple and rugged diode laser LDV that measures a single point on the ground. Multiple diode systems or a scanning mirror placed in front of the diode LDV are some of the strategies used to measure multiple points. The second system is a multi-beam LDV that uses a single YAG laser and diffraction optical elements to create an array of laser beams and thus multiple measurement points on the ground. The data obtained with LDV consist of velocity profiles at each point of the surface illuminated by each of the beams. By interrogating multiple points (with multiple vibrometers or with a multi-beam vibrometer) the system can ascertain with high probability the presence of a buried landmine. The systems exhibit a velocity resolution of about 1 micron per second, which is suitable for landmine detection. Low-frequency (100 kHz) carrier is employed in the multi-beam system to further enhance its performance with the acoustic/seismic technique.
An acoustic landmine detection confirmatory sensor using continuously scanning multibeam LDV
Authors: Sabatier James M. , Aranchuk Vyacheslav
Published: September 2013

Acoustic-to-seismic coupling technology using an LDV as a vibration sensor has proved itself as a potential confirmative sensor for buried landmine detection. One of the most important objectives of this technology is to increase the speed of measurements. Traditionally used point-by-point scanning LDVs cannot provide fast measurements. A moving platform that uses 16 LDVs and a continuously scanning single-beam LDV has been used to increase the speed of detection of buried landmines. Recently a multibeam LDV simultaneously probing 16 positions on the ground has been developed and successfully used for landmine detection. In this work, we report the use of a continuously scanning multibeam LDV as a confirmatory sensor for acoustic landmine detection. The multibeam LDV simultaneously illuminates the ground in 16 points spread over a 1-m line. A scanning mirror moves all 16 laser beams across the line. An airborne sound source in the frequency range of 80–300 Hz has been used to excite vibrations in the ground. The system enables scanning a 1-m by 1-m area and provides the vibrational pattern at the surface of the ground in a much shorter time than with previous scanning techniques.
A different approach for processing multibeam laser Doppler vibrometer (LDV) data
Authors: Wagstaff Ronald A. , Gilbert Kenneth E.
Published: September 2013

Exciting the ground with an acoustic tonal projected by a loudspeaker is a well-known method for detecting buried landmines. The subsequent ground motion is measured with a laser Doppler vibrometer (LDV). The LDV data contain the tonal in a frequency-modulated form. One approach for demodulating the data and extracting the tonal uses a Hilbert transform. The ground velocity can be obtained from these data to identify mine presence or absence. An alternate approach to mine detection is to perform consecutive fast Fourier transforms on the modulated LDV data, and to average the output powers in each spectral bin. This results in a ground velocity distribution function in the spectrum. The proximity of the beams to a mine (over, near, not near) can be determined from the width of the velocity distribution functions. Furthermore, the velocity distribution functions provide additional information that previous techniques do not. Such information may be useful, e.g., the possibility of separating mines from false targets. This new technique will be discussed, and the results from measured multibeam LDV data will be presented. [This material is based upon work supported by the U. S. Army Communications-Electronics Command Night Vision and Electronic Sensors Directorate under Contract DAAB15-02-C-0024.]
Rapid high spatial resolution imaging of ground vibration for buried landmine detection using ESPI
Authors: Alberts William C. , Sabatier James M. , Aranchuk Vyacheslav
Published: September 2013

Recent work has shown that many landmines exhibit a multimode vibration pattern. To fully map the vibration pattern of these modes requires spatial resolutions on the order of millimeters. Any practical field instrument to detect landmines that cues on such modal patterns must take advantage of parallel optical processing. An optical technique that lends itself to such vibration sensing is an electronic speckle pattern interferometer (ESPI). The double-pulsed ESPI system has been used for the vibration measurement of the ground surface. The first and second laser pulses synchronized with the vibration peak and the vibration valley, respectively, illuminate the object. The imaged object wavefronts are combined with a reference wavefront and recorded in two video frames by using a CCD camera. The spatial distribution of the 2D vibration amplitude is obtained by subtracting two speckle patterns and processing the corresponding fringe pattern. The displacement sensitivity of the ESPI is about 30 nm. Here, we not only consider airborne sound sources to excite vibrations in the ground, but also a mechanical shaker to significantly increase the vibration amplitudes at the spot of interest. The vibrational pattern at the surface of the ground over buried antitank and antipersonnel landmines is studied.
Inspection of the interior of a collapsing bubble via molecular dynamics
Authors: Lauterborn Werner , Kurz Thomas , Metten Burkhard , Schanz Daniel
Published: September 2013

Strongly collapsing bubbles emit shock waves, faint light flashes and induce chemical reactions. At present, the interior of a collapsing bubble is not yet accessible experimentally to reveal the processes behind this behavior. Thus our knowledge has to be advanced theoretically. The standard method relies on solving a set of partial differential equations. However, in the case of small sonoluminescent bubbles, the number of molecules may become too small for a continuum approach. Therefore, the processes within collapsing sonoluminescent bubbles are investigated by molecular dynamics simulations. The temperature, density and pressure distribution within the bubble are calculated. Whereas mass and heat diffusion inside the bubble are automatically accounted for, they must be explicitly introduced across the boundary to the liquid. In particular, also the dissociation of water vapor and chemical reactions of the dissociation products are taken into account. Results are presented for different acoustic driving conditions (sound pressure amplitude and frequency) and different gas compositions including mixtures of noble gases and water vapor. A prediction of the light emission is given to connect the calculations with observable parameters.
From blood to bubbles: Time resolved micro-particle detection and characterization by scattered ultrasound
Authors: Roy Ronald A.
Published: September 2013

Robert Apfel believed in the creative application of acoustics technology to difficult problems in biomedical sensing. Much of his work in this area focused on material characterization, with the intention of effecting diagnosis. His early work in blood cell characterization employed acoustic levitation to measure the bulk mechanical properties of human red blood cells. This subsequently paved the way to the use of high-frequency acoustic scattering to yield the compressibility and density of individual blood cells. Technology developed in this later effort was then adapted to the very difficult problem of transient micro-cavitation detection, and the active cavitation detector (ACD) was born. This paper traces this line of work from its origins and, in the process, serves to celebrate Bob Apfel’s peerless ingenuity and irrepressible creativity.
Active cavitation detection of asymmetrical inertial cavitation
Authors: Everbach E. Carr
Published: September 2013

The active cavitation detector (ACD) developed in Bob Apfel’s laboratory has often been employed to quantify pressure thresholds for inception of symmetrical inertial cavitation of microbubbles. In the current application, however, a 30-MHz ACD interrogates individual echo-contrast agent bubbles adhering to a Mylar(TM) sheet that are driven into asymmetrical (jet-producing) collapse by a 1-MHz toneburst (>1 MPa pp). The resulting ACD output suggests that asymmetrical bubble collapse is slower than symmetrical collapse, producing less total radiated acoustic power. ACD output mixed with reference sinusoids at 30 MHz and low pass filtered yields Doppler signals that may be useful in quantifying asymmetrical collapses under biomedically relevant conditions, such as on endothelial walls.
Fabrication of PLGA polymer microspheres for U. S. mediated gene delivery
Authors: Williamson Rene G. , Saltzman William M. , Brandsma Janet L.
Published: September 2013

The promises of gene therapy remain unfulfilled because of the lack of a safe and efficient method for transfecting DNA into cells. PLGA has been used as a vehicle for protein, drug, and gene delivery applications because of its biocompatibility and sustained release properties. PLGA polymer microspheres offer advantages of safety and the possibility of sustained intracytoplasmic delivery. The PLGA also protects the plasmid from degradation. Using the double-emulsion microsphere fabrication technique, a new DNA delivery vehicle, comprising of plasmid DNA and octafluoropropane gas encapsulated in PLGA polymer and PVA stabilizer (Sonospheres) was made. The encapsulated gas offers acoustic activity to the microspheres, which enables them to undergo cavitation in an acoustic field. The goal is to lead to increased DNA transfection when these Sonospheres are subjected to an acoustic field in the MHz frequency range. A summary of the fabrication methods and some initial in vitro studies will be presented.
Compression in the cochlea
Authors: Ruggero Mario A.
Published: September 2013

Cochlear compression consists of the reduction of the amplitude range of the auditory signal, from 6 orders of magnitude at the stapes to (typically) 1–2 orders of magnitude in the spike rate of individual cochlear afferents. Psychophysical discussions of compression generally focus on basilar-membrane (BM) vibrations at the base of the cochlea, which at the characteristic frequency (only) grow with stimulus intensity at remarkably compressive rates but exhibit almost negligible harmonic distortion. In apical cochlear regions, however, BM compression appears to be substantially weaker than at the base, involves significant dc and harmonic distortion, and is not confined to frequencies near the characteristic frequency. Additional stages of compression exist in mechanical-to-electrical transduction in inner hair cells and in the spike generation mechanism. Both the regional variations in the features of BM nonlinearities and the additional compression introduced by proximal stages of signal transformation should be addressed in physiology-based psychophysical models of auditory processing. Ideally, such models should take into account off-frequency listening and should be based on the output of the cochlea, i.e., the activity of the entire array of cochlear afferents, which is better known and more relevant to central auditory processing than BM vibrations. [Work supported by NIH.]
Perceptual consequences of normal and abnormal peripheral compression: Potential links between psychoacoustics and speech perception
Authors: Oxenham Andrew J. , Rosengard Peninah S. , Braida Louis D.
Published: September 2013

Cochlear damage can lead to a reduction in the overall amount of peripheral auditory compression, presumably due to outer hair cell (OHC) loss or dysfunction. The perceptual consequences of functional OHC loss include loudness recruitment and reduced dynamic range, poorer frequency selectivity, and poorer effective temporal resolution. These in turn may lead to a reduced ability to make use of spectral and temporal fluctuations in background noise when listening to a target sound, such as speech. We tested the effect of OHC function on speech reception in hearing-impaired listeners by comparing psychoacoustic measures of cochlear compression and sentence recognition in a variety of noise backgrounds. In line with earlier studies, we found weak (nonsignificant) correlations between the psychoacoustic tasks and speech reception thresholds in quiet or in steady-state noise. However, when spectral and temporal fluctuations were introduced in the masker, speech reception improved to an extent that was well predicted by the psychoacoustic measures. Thus, our initial results suggest a strong relationship between measures of cochlear compression and the ability of listeners to take advantage of spectral and temporal masker fluctuations in recognizing speech. [Work supported by NIH Grants Nos. R01DC03909, T32DC00038, and R01DC00117.]
Cochlear nonlinearity between 500 and 8000 Hz in listeners with moderate cochlear hearing loss
Authors: Lopez-Poveda Enrique A. , Plack Christopher J. , Meddis Ray , Blanco Jose L.
Published: September 2013

For two listeners with flat hearing loss, temporal masking curves (TMCs) were measured for probe frequencies (Fp) of 0.5, 1.0, 2.0, 4.0, and 8.0 kHz and masker frequencies of 0.5, 0.6, 0.7, 0.9, 1.0, 1.05, 1.1, and 1.2 Fp. From these, basilar membrane (BM) input/output (IO) functions and psychophysical tuning curves (PTCs) were derived and compared with corresponding data for normal-hearing listeners. Linear IO functions were observed for one ear only and for probe frequencies of 4 kHz and above. This result is consistent with the consequences of severe outer hair cell (OHC) damage on the BM response. Elsewhere, however, IO functions showed residual compression, with slopes in the compression region close to normal. This suggests that either the impairment relates mostly to inner hair cell (IHC) dysfunction, or that OHC dysfunction reduces the gain of the BM at low levels while maintaining the degree of maximum compression. The data suggest that the active and the passive BM mechanisms have different relative positions (in frequency) in the apical and the basal regions of the cochlea. Across probe frequencies, the slopes of the TMCs for off-frequency maskers are shallower for the impaired ears. It is considered that this possibly reflects IHC-related compression.