bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of modulation and laterality on the perception of time-varying sinusoidal sentences in noise
Authors: Richter Melanie M. , Carrell Thomas D.
Published: February 2014

Researchers have shown amplitude modulation significantly increases the intelligibility of time-varying sinusoidal (TVS) sentences [T. Carrell and J. Opie, Percept. Psychophys. 52, 437–445 (1992); J. Barker and M. Cooke, Speech Commun. 27, 159–174 (1999)] and ameliorates the effect of multispeaker babble on intelligibility at moderate signal-to-noise ratios [T. Carrell, J. Acoust. Soc. Am. 93, 2327 (1993)]. These effects have been attributed to the ability of amplitude comodulation to create auditory objects. However, other characteristics of acoustic signals cause components to group together, the classic example being sound location in the cocktail party effect [C. Cherry, J. Acoust. Soc. Am. 25, 437–445 (1953)]. In natural environments, acoustic cues work together to assemble and segregate auditory objects for auditory scene analysis [A. Bregman, Auditory Scene Analysis (1990)]. The present study examined the interaction of amplitude modulation and laterality on the intelligibility of TVS sentences in noise. Forty females listened to TVS stimuli in a 2×2×2 factorial design experiment: modulation (100 Hz versus unmodulated) by laterality (diotic versus dichotic) by noise (S/N=+5 dB vs −15 dB). Modulation and noise demonstrated large main effects in the expected direction, but effects of laterality were minimal.
The basic units of rate normalization
Authors: Newman Rochelle S.
Published: February 2014

Individuals vary their speaking rate, and listeners use the duration of adjacent segments to adjust for these changes [Miller and Liberman (1979); Newman and Sawusch (1996)]. However, it has not been clear what these ‘‘segments’’ actually are. We examined whether two-phoneme sequences would produce two separate rate normalization effects (one for each phoneme), or only a single effect. We created series such as ‘‘shkib-chkib’’ and ‘‘shwib-chwib’’ and examined effects of the /k/ or /w/ and /I/ durations on perception of the initial contrast. Altering the /k/ duration resulted in a rate normalization effect different from that caused by varying the duration of the sequence ‘‘kib’’ as a whole. This suggests that /k/ and the vowel are treated as separate units of speech. However, we did not find this pattern for the /w/. For sequences such as ‘‘kih,’’ which have obvious acoustic boundaries, each phoneme has a separate rate normalization effect. For sequences such as ‘‘wih,’’ without such obvious cues, the sequence is treated as a single (larger) segment by the rate normalization process. This suggests that rate normalization is not based on phonemes, but on segments with obvious acoustic boundaries, emphasizing the role of basic auditory processing in speech recognition.
Identification of multiple consonants in binaural presentation
Authors: Kwon Bom Jun
Published: February 2014

How well do we process multiple speech sounds presented concurrently? Consonant identification was tested with normal-hearing listeners using 13 voiced consonants, which were recorded by 10 speakers and had similar durations of murmur or voice bar, in syllable-initial position. Listeners were presented with multiple (up to four) stimuli with a time delay between the stimuli via headphone either diotically or dichotically (to simulate spatial separation between sound sources). Results showed that while the identification scores decreased as the delay decreased, performance was still quite robust even with the zero delay. The scores for diotic presentation were lower than those for dichotic presentation, but the difference was not overwhelming compared to the decrease in the score due to the delay. The data suggest that (i) listeners are capable of processing and identifying multiple consonants in concurrent presentation, and (ii) the effect of onset differences is more substantial on identification of multiple sounds than binaural separation. In other words, the ‘‘cocktail party’’ effect can occur even when there is no spatial separation between sound sources. A possible mechanism of identification of multiple consonants, when the cues to segregate each stimulus is highly limited, will also be discussed. [Work supported by NIDCD and Quota Scholarship.]
English-speaking listeners’ sensitivity to allophone appropriateness in real and nonword speech perception
Authors: Jones Amanda K.
Published: February 2014

The question of whether adult listeners are capable of evaluating speech for the appropriateness of its allophonic content has received relatively little attention. Whalen et al. (1997) showed that English-speaking listeners preferred context-appropriate allophones when evaluating real words. However, for nonwords they found that listeners tended to prefer one particular allophone, regardless of its contextual appropriateness. In the current study, listeners provided naturalness ratings for pronunciations of both words and nonwords containing either an appropriate or an inappropriate allophone of the phoneme /t/ in initial /st/ clusters. The words and nonwords were divided into four categories determined by pretesting: highly familiar real words (e.g., ‘‘start’’), relatively unfamiliar real words (‘‘stave’’), highly wordlike nonwords (‘‘storch’’), and less wordlike nonwords (‘‘stimf’’). Results showed that listeners consistently preferred pronunciations that contained an appropriate allophone of /t/, regardless of stimuli category, e.g., real word vs nonword. This result contradicts Whalen et al.’s suggestion that ‘‘allophonic contrast... may require contact with the lexicon in order to affect production and perception.’’ Instead, the results indicate that English-speaking listeners have abstract concepts of allophonic appropriateness that they can apply to both existing lexical items and nonwords when evaluating these items for the naturalness of their pronunciations.
Ultrasonic pulse compression system with new approaches of signal processing
Authors: Mahmud Khan M. , Ohba Ryoji
Published: February 2014

A nonscanning method for ultrasonic flaw detection technique is described. The system employs an M-sequence modulated ultrasonic wave as the excitation signal. Irrespective of the number of faults to be detected, the data acquisition system predeterminedly consists of a transmitter and a few receivers to be fixed at convenient locations. The cross-correlation function (CCF) between the original M sequence and the demodulated received sequence indicates the presence of faults in the form of sharp peaks. In order to clearly detect the expected peaks corresponding to the faults in the CCF, new signal processing techniques are proposed. The novel design approach of inverse filter and synchronous moving average are found to be very effective in eliminating the false peaks from the CCF while increasing the signal-to-noise ratio significantly. A way of using the clean algorithm from a diverse field is proposed, which shows tremendous potential in ultrasonic NDT for the distinction of close peaks removing all sidelobes. Experimental results (on metal plate) demonstrate the capability of the system and confirm the feasibility of the approach under heavy ambient noise condition. An algorithm, only on the basis of travel time of the signal, to determine the exact location of a fault is described. [The authors would like to express their gratitude to the Ministry of Educaion, Japan, for the funds needed for this research.]
Inversion methods for Lamb and Rayleigh wave surface holography
Authors: Teramoto Kenbu , Yuasa Hajime
Published: February 2014

Lamb and Rayleigh wave surface holographies have advantages for nondestructive testing of concrete and steel structures that is based on the use of generated surface acoustic waves that propagate over the concrete and steel and are reflected by external cracks. When the surface wave field is observed by a circular array of surface wave transducers, the proposed method that is called ‘‘eigenfunction series expansion (EFSE)’’ can reconstruct exact images of the scatterers within the array. This holographic imaging system has the following features: (1) An inversion via expansion in eigenfunction series produces much higher resolution than one which a back propagation produces. (2) An iso-azimuthal signal processing enables to design a first image reconstruction procedure. In this study, the computational process in EFSE and wave fields near the cracks are discussed and their physical meanings are investigated through FEM simulations. The surface wave transfer function by EFSE permits an effective regularization of the source field with cracks: this is possible because the transfer function includes several wave modes at the cracks and surface wave fields. In particular, it is clearly shown that the reconstructed image can be improved by adopting EFSE method that suppresses the spurious lobes.
Acoustic scattering from laser damage spots
Authors: Chambers David H. , Martin L. Peter , Thomas Graham
Published: February 2014

High energy laser systems sustain damage to critical optical components over their lifetime. This damage is manifested as localized pitting and cracking in the glass components. The damage pits have complicated morphology consisting of a hemispherical pit lined with crushed material, and surrounded by an outer zone with cracks. Monitoring of damage is necessary in some applications to prevent catastrophic failure of critical components. An acoustic system for monitoring optical damage spots was investigated to determine its applicability for the National Ignition Facility (NIF) at LLNL. Experiments and simulations of acoustic scattering from damage spots were performed to assess the ability to detect and size optical damage before failure becomes imminent. Pulses with a center frequency of 5 MHz were scattered from damage spots with nominal sizes of 0.5 mm to 7 mm. The amplitude of the measured return showed evidence of resonant scattering from the complicated morphology of the pits. This was confirmed with numerical simulations of scattering from simplified models of damage spots. This talk will emphasize the physics of scattering from damage spots and the comparison between experiments and numerical simulations.
A new acoustical method for inspection of industry piping
Authors: Khan Ishtiaq Rasool , Ohba Ryoji
Published: February 2014

A new acoustical method for inspection of the industry piping against development of corrosion and early stage cracks is presented. Impulse response of a defective pipe is obtained by launching an M-sequence at an end of the pipe, and cross-correlating it with the sequence received at the same end. The received sequence contains several replica of the M-sequence, reflected from various objects including the defects in the inner wall of the pipe. Therefore, the impulse response contains a peak corresponding to each reflection, the location of which determines the location of the reflecting object. Signal processing techniques are used to detect these very small peaks from heavy noise, and to distinguish the wanted peaks (due to defects) from unwanted peaks (due to other objects). A new technique is presented, which removes all kinds of unwanted peaks and other noise and significantly enhances the wanted peaks. This technique is proved much better than the classical noise removal techniques of moving average, subtraction and inverse filtering. A very simple experimental setup is presented and the results of successful detection of defects of different sizes in pipes of different dimensions are presented. [The presented research was financially supported by Japan Society for Promotion of Science.]
Locating a sound source of unstable frequency by use of phase tracking
Authors: Poole Travis L. , Frisk George V.
Published: February 2014

When the frequency of a cw source is known precisely, it is possible to relate the time rate-of-change of the measured phase to the time rate-of-change of the distance between source and receiver. However, when the source frequency is not known precisely, or when the source frequency is unstable, an unknown time dependence will remain after demodulation, causing the phase to appear to vary rapidly. Thus, the phase cannot be used to find the rate of separation of the source and receiver. By examining the difference between the phase measured by two independently moving receivers, it is possible to eliminate this unknown time dependence from the phase. In this talk, a source localization method based on this idea is presented and applied to data from a frequency-unstable source (near 20 Hz) in a shallow-water, low-frequency acoustics experiment. [Work supported by ONR and the WHOI Education Office.]
Matched-phase matched field processing: Searching for the phases
Authors: Orris Gregory J. , Nicholas Michael
Published: February 2014

There have been several methods explored in the literature by which standard single-frequency matched-field techniques can be extended to multifrequency coherent algorithms. The foremost difficulty in implementing any coherent algorithm is the lack of reliable estimates of the relative phases of the processed frequency components. Thus many coherent techniques have side-stepped this issue by assuming an inter-frequency phase relationship that is either known a priori, or trivially zero. To address this deficiency we have developed the matched-phase matched-field processor [Orris et al., J. Acoust. Soc. Am. 107, 2563–2575 (2000)]. The approach is to enlarge the search space from only the spatial dimensions to include the interfrequency phases. This processor has been applied to data from a source of known characteristics and was found to increase the spatial resolution while simultaneously increasing array performance significantly (received levels below −15 dB). We also present an application to a source of opportunity (i.e., a passing surface vessel) with unknown acoustic signature.
Information theory for matched field processing: preliminary results
Authors: Buck John R.
Published: February 2014

Matched field processing (MFP) has traditionally been considered as an estimation problem in which the goal is to use the observed pressure field and an acoustic propagation model to estimate an unknown source location with the smallest possible variance. An alternative perspective is to divide the search region into cells whose size is dictated by logistical constraints, and attempt to assign the source to one of these cells. In this perspective, the goal of MFP is to minimize the probability of error in assigning the source to a grid cell, rather than minimizing the variance of the source location estimate. This perspective leads one to consider MFP as a communication problem in which the source transmits its location to the receiver array. Information theory provides techniques which can bound the amount of information available to the receiver in this problem. The amount of information observable has implications for the performance limits achievable by any MFP algorithm. Additionally, this perspective leads to methods of designing arrays for MFP which maximize the average information observed over the search space. [Work supported by ONR Young Investigator Program.]
Matched field processing using a large aperture planar towed array
Authors: Munro Jennifer , Baggeroer Arthur , Ward James , Tracey Brian
Published: February 2014

Passive detection and localization in shallow water is complicated by high transmission loss and coherent multipath generated by bottom interaction. To compensate for this loss, one must achieve as much array gain as possible. The seismic community has developed large aperture arrays designed for low-frequency operation, which are on the order of 3–10 km by 0.5 km in size. This presentation explores the applicability of these arrays to passive detection and localization of underwater targets using matched field processing (MFP). This approach offers the advantages of a high number of sensors, large gain focusing, and three-dimensional localization through MFP when the propagation environment is well known. This talk presents simulated results of conventional MFP using planar arrays in the presence of surface interferers. This presentation continues showing improvement through adaptive MFP. It then examines the problem of target motion. For these large arrays, robustness to target motion becomes a significant challenge. [This work was sponsored by the Defense Advanced Research Projects Agency under Air Force Contract No. F19628-00-C-0002. Opinions, interpretations, conclusions, and recommendations are those of the authors and not necessarily endorsed by the United States Air Force.]
Energistics Laboratory facility
Authors: Cerami Victoria , Stegall Jack
Published: February 2014

Energistics Laboratory in Houston, Texas is a leading laboratory for the testing of HVAC equipment. For over 15 years, this facility has ensured the highest standards in leading-edge HVAC technology and architectural testing capabilities. Testing capabilities include both industry standard rating procedures, and mock-up testing to simulate field conditions. The laboratory is open to developers, owners, architects, engineers, general contractors, manufacturers and others who require independent component testing and evaluation.
USG Corp. Research and Technology Center’s Acoustical Testing Facility
Authors: Payne Stephen W.
Published: February 2014

The Acoustical Testing Facility at the USG Corp. Research and Technical Center was commissioned in 1996. The Facility contains structurally isolated test chambers housed within an exterior shell. The Facility includes chambers for performing sound tansmission loss tests per ASTM E90, sound absorption tests per ASTM C423, ceiling attenuation tests per ASTM E1414 and interzone attenuation tests per ASTM E1111. In addition to testing per ASTM standards, tests can also be performed to ISO Standards. The chambers are designed to provide maximum isolation from external noise. The chamber walls, roof and floor are built of a minimum of 8-in. (200-mm) solid concrete or filled concrete block. In addition the reverberation chamber is mounted on an independent spring system. The Facility is accredited under the National Voluntary Laboratory Accreditation Program (NVLAP) and under the Underwriters Laboratories Client Data Test Program. The main function of this Facility is to provide data for new product and systems development and to provide testing under the UL Acoustical labeling program.
Qualification of WEAL Reverberation Chamber
Authors: Mange Gary E.
Published: February 2014

Western Electro-Acoustic Laboratory (WEAL) has recently qualified a new reverberation chamber. Qualification measurements were performed for absorption testing (ASTM C423) and sound power testing (ANSI S12.31 and S12.32). Results are shown at various stages of the qualification.
Georgia Institute of Technology—Integrated Acoustics Laboratory
Authors: Cunefare Kenneth A. , Biesel Van
Published: February 2014

The Integrated Acoustics Laboratory of Georgia Tech’s School of Mechanical Engineering is a state-of-the-art facility dedicated to acoustic and vibration research. The current centerpiece of the lab is an anechoic chamber with interior dimensions of 17 ft × 17 ft × 12 ft. Laboratory instrumentation includes a 32-channel HP VXI data acquisition system, full LMS CADA-X data acquisition and analysis package, HP-VEE, a two-channel Siglab analyzer, Polytec PSV-200 scanning laser Doppler vibrometer, and a host of microphones, accelerometers, shakers, and load cells. The laboratories also feature a brake dynamometer. Two finite-element modeling stations are equipped with MSC/NASTRAN and COMET/Acoustics software for the complete modeling of vibration and acoustics. The laboratory will be expanded this year to include a reverberation room, which will be attached to the existing anechoic chamber by a hatch for transmission loss testing. The expansion will also add a semi-anechoic chamber to the lab.
The new Blachford acoustics laboratory
Authors: Moritz Charles
Published: February 2014

In 1968, HL Blachford, Inc. constructed their first acoustics laboratory next to their Troy, Michigan plant. This laboratory consisted of a 216-m3 reverberation room with an adjacent large hemianechoic room approximately 12 m long, 5 m wide, and 4.5 m high. After several ownership changes, a plant that used to belong to HL Blachford, Inc. was purchased in 1995 by HL Blachford Ltd. of Canada, and became the new headquarters of a new company called Blachford, Inc. It quickly became obvious that a new laboratory was required for vehicle testing and acoustical material development. The design of a new facility began in 1997 and was based on the old laboratory; however, the new design incorporates design changes to increase the capacity, capabilities, and quality of the facility. The new laboratory is currently under construction and features a larger hemi-anechoic room, approximately 15 m long, 9 m wide, and 6 m high, and a nonadjacent 200-m3 reverberation room with several horizontal and vertical test sections for vehicle component and material testing.
Neuromorphic system for real-time biosonar signal processing
Authors: Edwards R. Timothy , Cauwenberghs Gert
Published: February 2014

Real-time classification from active sonar echolocation requires tremendous computational power, yet is performed effortlessly by bats and dolphins. Special-purpose, yet programmable and reconfigurable hardware tailored to the parallel distributed nature of the computation performed in biology, is presented. The system contains a front-end cochlear processor implemented as an analog filterbank, and a pattern recognition engine classifying the front-end time-frequency features. The reconfigurable front-end supports up to 34 bandpass channels spanning the 10 to 100 kHz range typical of bat and dolphin sonar. A support vector machine (SVM) classifies the features. In an alternative realization, an integrate-and-fire neural network uses the zero-crossings of the front-end bandpass channel outputs. The internal variables may be represented in numerous ways by reprogramming the hardware, giving the system great flexibility in representing features to match the methods used by various biosonar algorithms. Experimental results demonstrate the capabilities of the processor, classifying the CSS (Panama City) linear frequency modulation (LFM2) data in real-time. Implementation issues for alternative representations of biosonar signals are also discussed. [Work supported by ONR N00014-01-1-0315.]
What kinds of auditory mechanisms explain biosonar perception by FM bats?
Authors: Simmons James A. , Sanderson Mark I. , Eastman Kyler M.
Published: February 2014

A biological SCAT model of target ranging in FM-bat biosonar integrates (1) acoustic ecology with algorithms identified from (2) peripheral auditory representations and (3) central auditory processing to account for biosonar performance. The bat’s auditory spectrograms incorporate a near-ideal time-frequency compromise and can outperform a simple matched filter for detection of natural targets. Neural coding of delay appears to have submicrosecond accuracy at brain-stem, midbrain, and cortical levels, and can explain ranging and azimuth performance for single targets. In contrast, inner-ear integration-time convolution required to match echo reception to the structure of natural targets blurs delay resolution to hundreds of microseconds, and this is retained in the recovery time of brain-stem responses. Analysis of field performance and laboratory tests both show the bat’s delay resolution to be ∼2–5 ms, however, midbrain responses constitute delay lines that can support tracking of prey and both coarse target ranging and deconvolution for fine resolution down to 6 ms. Cortical coincidence-detecting neurons test all combinations of pulse-echo delay and spectral profile contingencies to display coarse and fine range. Their characteristics predict bandwidth-squared dependence of submicrosecond hyperresolution, which is confirmed in jittered-echo experiments. The physical embodiment of individual targets in neural responses appears to be dynamic rather than by place.
Temporal estimation by a model big brown bat
Authors: Wotton Janine M. , Ferragamo Michael J. , Sonbuchner Timothy M. , Sanderson Mark I.
Published: February 2014

The big brown bat, Eptesicus fuscus, uses echolocation to locate prey and displays extraordinary acuity in the perception of temporal cues in acoustic signals. Behaviorally the bat can detect changes at submicrosecond levels but individual neurons in the inferior colliculus (IC) and cortex operate with much less precision. Most of these cells are poor temporal markers with response variation on the order of a few milliseconds and some in tens of milliseconds. A temporal estimator was created incorporating the response properties of recorded neurons and behaviorally appropriate limitations on the number of echolocation emissions. The response of the neurons can be characterized as probability density functions in time and frequency. The characteristics of these neurons were used to create large simulated populations of IC and cortical neurons that show the full range of recorded variation. The connections between these two populations were simulated using a self-organizing neural network. If more than one IC neuron is required to trigger the response of each cortical neuron then the model operates with resolution of microseconds. Manipulating the firing threshold of cortical cells and the relative population sizes influences the errors in target estimation.
Binaural hearing in dolphins
Authors: Moore Patrick W. B. , Brill Randall L.
Published: February 2014

Binaural hearing is an advantage of having two ears. Human benefits are evident in a 3-dB threshold difference, the ability to localize sound sources in space, and the ability to isolate primary sounds from corresponding echoes. The binaural capabilities of dolphins are relatively unexplored. Studies show that their localization of pure tones underwater is mediated by the same mechanisms observed in terrestrial mammals. Behavioral evidence from free-field localization studies supports reliance on time and intensity cues. Two studies have examined binaural hearing in dolphins using contact hydrophones to isolate the hearing mechanisms. They provided masking level differences (MLDs) comparable to humans and interaural time and intensity difference thresholds that were better than any recorded for terrestrial mammals. Neurophsyiological studies using evoked potentials investigated interaural sensitivity and intensity differences as a function of multiple frequency stimuli presented at various angles around the head of a dolphin. Recent behavioral studies have mapped the acoustic sensitivity around the head and lower jaw. Those results suggest greater sensitivity forward of the panbone, thought to be the site of best reception, and an asymmetry in sensitivity that may be analogous to that observed in other animals such as the barn owl.
Matched field processing of existing binaural dolphinlike signals for MCM
Authors: Tolstoy A. , Au W.
Published: February 2014

A new matched field processing (MFP) approach has been applied to existing (but limited) dolphinlike binaural data. The frequencies range from 25 to 200 kHz with the received quasi-monostatic echo lasting less than 4.0 ms. The data discussed consist of backscatter echoes from a mud bottom, a drum buried in the bottom, and a Manta-like object also buried in the bottom. The MFP approach (using NO modeling of any kind) was designed to extract differences between apparently similar signals. Since the available data show overly strong and different returns for all the targets, we first manipulate the data to bring them more into line with expectations. The new data were then processed to yield a target ‘‘template’’ of scattered returns as a function of time and frequency characterizing the target returns. These templates can easily be used to detect and identify scattering from targets on or in the bottom in low S/N situations. [Work supported by ONR.]
Consistency of echolocation signals of CF-FM bat measured by a telemetry system
Authors: Riquimaroux Hiroshi , Yamasumi Kenji , Watanabe Yoshiaki , Lin Liang-Kong
Published: February 2014

The purpose of the present study was to examine the daily consistency of the constant frequency component (CF) of CF-FM bats and to test the significance of a telemetry microphone system (telemike) mounted on the bat’s head. We examined sonar sound characteristics of leaf-nosed bats (Hipposiderous terasensis) when bats were at rest and during flight. Experiments were done within a steel-walled chamber. Their emitted pulses were simultaneously recorded by a fixed microphone at the wall and the telemike. The second harmonic of the CF component (CF2) at rest and during flight varied significantly over several months. When at rest, the fundamental frequency of the bat was about 35 kHz. The second harmonic was the most intense. There was little difference between data taken from two different microphones when at rest. However, during flight we found significant differences between data obtained by the microphone at the wall and the telemike. We could see a systematic change in CF2 frequency during flight through the telemike. Our findings may suggest that the bats compensated for the frequency of the CF component of their pulses by detecting Doppler-shifted CF of returning echoes from the target. We will discuss the individuality and consistency of the CF component during flight and at rest. [The present research was supported by Special Research Grants for the Development of Characteristic Education from the Promotion and Mutual Aid Corporation for Private Schools Japan, a grant to RCAST at Doshisha University from the Ministry of Education, Japan and Doshisha University’s Research Promotion Fund.]
Broadband PE/SSF modeling in 2-D and 3-D
Authors: Tappert F. D.
Published: February 2014

Prediction of pulse propagation for the 2-D and 3-D test cases proposed for benchmarking range-dependent numerical models is accomplished with the c0-insensitive version of the broadband parabolic equation with the split-step Fourier (PE/SSF) algorithm numerical model that takes advantage of efficient Fourier syntheses from the frequency domain to the time domain. Special attention is paid to the fast and accurate prediction of the travel times and amplitudes of the resolved multipath arrivals, as well as to the unresolved multipaths. The role of chaos in limiting accurate pointwise predictions in range-dependent (nonseparable) propagation problems is highlighted. [Work supported by ONR Code 321OA.]
Some normal mode and PE propagation predictions for selected benchmark test cases
Authors: Tolstoy A.
Published: February 2014

Results will be presented for the 3-D and shelf-break test cases. The 3-D problem results here will be for 2-D predictions only. The KRAKEN (adiabatic and coupled versions) and PE (energy conserving and nonconserving) models will be the primary codes investigated. It is found that it is nontrivial to run these codes even when one is familiar with them. It is also found that all the models generally agree, but there are some quantitive differences. [Work supported by ONR.]
An implementation of a three-dimensional wave propagation model in a parallel processing computational environment
Authors: Lawrence Thomas N. , Pound Richard D. , Jenevein Roy M.
Published: February 2014

A parallel processor implementation of a three-dimensional parabolic equation approach to acoustic wave propagation was developed using the University of Texas Cray T3E (Lone Star). Lone Star is currently an 84 processor machine. We will discuss results from modeling various underwater acoustic environments where three-dimensional results are required, and the computation speed-up achieved using a multiprocessor approach. High performance computing, i.e., computation on high speed multiple processor machines, is now entering the lower priced small computer era. Environmental acoustic problems heretofore ignored because of the computational intensity required can now be considered for operational field systems. Although the T3E is a mainframe machine, this model is being developed for a low cost clustered processor machine with a combination of shared and distributed memory, which we expect to have in operation this year. [Work sponsored under Independent Research and Development at the Applied Research Laboratories. Computer support on the T3E is funded by the National Partnership for Advanced Computational Infrastructure through the University of Texas Advanced Computing Center for Engineering and Science.]
3-D benchmarking with a three-dimensional azimuthal wide-angle model in the wedge
Authors: Lin Ying-Tsong , Chen Chifang , Lee Ding
Published: February 2014

In predicting wave propagation in either direction, the size of the angle of propagation plays an important role; thus, the concept of wide-angle is introduced. Most existing acoustic propagation prediction models do have the capability of treating the wide-angle but the treatment, in practice, is vertical. This is desirable for solving 2-dimensional (range and depth) problems. In extending the 2-dimensional treatment to 3 dimensions, even the wide-angle capability is maintained in most 3-D models, it is still vertical. This paper uses an azimuthal wide-angle wave equation. The 3-D benchmarking is done by a 3-dimensional azimuthal wide-angle model with real 3-D side-wall boundaries for up-slope calculations. The cross-slope calculations are also done for both subcases. [Work supported by National Science Council of Republic of China.]
A research of sound rays propagated in sloping seabed ocean
Authors: Jiang Guanting , Guo Shengming
Published: February 2014

The property of sound waves transmitted through sea water always presents an important problem in acoustics. In this paper, sound rays propagated underwater on an irregular seabed were calculated and some interesting results were received. Sound transmitted amplitude is lower than in a plane seabed sea, and in a slope sea bottom the direction of the sound ray will turn deflexion along the bed. All of the results are obtained using the ray-trace method.
Calibration and use of a broadband ADCP to measure zooplankton volume scattering strengths
Authors: Benfield Mark C. , McGehee Duncan E. , Keenan Sean F. , Deines Kent L.
Published: February 2014

A 1200 kHz broadband ADCP from RD Instruments was calibrated and used to collect quantitative volume backscattering data from zooplankton in the Gulf of Mexico. Voltages on the four receivers, reported in terms of ‘‘counts,’’ were linear with respect to received sound pressure level in dB re 1 μPa, with sensitivities of 2.376 to 2.434 counts/dB, depending on the receiver. Source levels ranged from 212.9 to 214.6 dB re 1 μPa at 1 m. The ADCP was mounted on the C/V Admiral Semmes and used to survey volume backscattering around an oil platform in the Gulf of Mexico. Volume backscattering strengths measured between −40 and −90 dB, which were generally consistent with independent observations of the numbers and sizes of scatterers present in the water column. These results suggest that, with careful calibration, ADCPs may be used for quantitative zooplankton research.
Evaluation of vibratory coherence as an alternative to radiography in assessing bone healing after osteo-distraction
Authors: El-Bialy Tarek H. , Royston Thomas J. , Sakata Akira
Published: February 2014

Distraction osteogenesis is used in orthopedics to lengthen bones, by cutting or breaking the bone and gradually separating the two pieces as new bone fills the intervening space. There is a need for early assessment of the degree of bone healing that allows for normal functioning without unwanted side effects. This study compared different techniques used to evaluate the degree of bone healing during mandibular osteodistraction in 21 rabbits. For each rabbit, the mandible was cut in a surgical procedure and then 72 h later distraction began at a rate of 3 mm per day. Bone formation at the distraction site was assessed by in vivo photodensitometry on head radiographs, an in vivo (nondestructive) vibratory coherence test across the distraction site, a post-mortem, ex vivo (destructive) three-point bending mechanical test, and by post-mortem, ex vivo (destructive) histological examination. Statistical analyses included analysis of variance (ANOVA) and correlation coefficient tests. The findings revealed that the results of bone photodensity and the vibration technique are positively correlated to the results of the mechanical three-point test and histological examination. The use of the vibration technique may provide a substitute for or augment the routine use of radiography for in vivo evaluation and monitoring of bone healing.
Physical mechanisms implied in ultrasound propagation through trabecular bones
Authors: Padilla Frederic , Laugier Pascal
Published: February 2014

Measurements of quantitative ultrasound parameters represent an established mean of skeletal status assessment in osteoporosis. However, to date, the exact physical mechanisms underlying ultrasound attenuation in cancellous bone have not been clearly documented. This study reviews the different mechanisms underlying propagation of ultrasound in trabecular bone, based on results obtained by our group and others. Bone is a porous, anisotropic, and scattering medium. Anisotropy of phase velocity has been explained with a multilayer model. Several attempts have been made to model the propagation with the Biot’s theory for poroelastic media. Encouraging results have been obtained for velocity. However, the viscous absorption mechanism implied in this theory disagrees with the experimental attenuation data and with the observed influence of fluid viscosity. Negative dispersion has been recorded, in agreement with some multiple scattering ideas. Several models of scattering (analytical and numerical) have given good predictions of backscattering coefficient. Despite the good results observed with these models, none of these could explain the experimental data, and especially the attenuation data. In conclusion, a more complex model will be discussed, to describe both absorption and scattering effects, as in geophysics for rock studies.
Ultrasonic pulse transmission technique to evaluate biomechanical properties of ACL graft substitutes
Authors: Kambhampati Krishna V.
Published: February 2014

The study aims at the identification of an ideal graft material for arthroscopy guided anterior cruciate ligament (ACL) reconstruction (ACLR). Ultrasonic pulse transmission technique was used to analyze the elastic properties (EP) of fresh human ACL, semitendinosus tendon (ST), middle one-third of patellar tendon (CPT) and cigarette rolled, distally based iliotibial band (CITB) grafts in an untwisted and incremented number of twists (two to eight times) at 1 MHz fundamental frequency. The results indicated that the strength of the graft depended upon its collagen density and the EP depended upon the pretensioning of the graft for ACLR. The EP were shown to have significant difference on selective pretensioning of the graft. The EP of CITB grafts changed after twisting. Rigidity of twisted CITB graft surpassed that of the ACL, ST, and CPT grafts. The CITB graft twisted five to seven times along its long axis is isoelastic with normal ACL and CITB graft twisted eight times is stronger than even CPT graft. Twisting of CITB graft provides initial strength and stiffness, necessary pretensioning and the balance between elasticity and rigidity is achieved to duplicate the EP of ACL. The success of ACLR depends upon using an isoelastic graft taken from a relatively, less important CITB.
Detection of ultrasound generated contrast bubbles in a refluxing canine model
Authors: Hwang Emma Y. , Fowlkes J. Brian , Carson Paul L. , Bloom David A.
Published: February 2014

A surgical reflux procedure, performed on two canines, was used to test a less invasive method for diagnosing urinary reflux. After approximately 6 weeks of recovery, examinations tested for reflux over the next 7 weeks. The canines were positioned prone (slightly head down) on a tilted table with a hole exposing the depilated abdomen, where a 1.18 MHz high intensity focused ultrasound transducer could be coupled. The reflux condition was evaluated first using standard fluoroscopy and x-ray contrast instilled in the bladder by a gravity feed through a transurethral catheter. For high grade reflux, dilute contrast agent (Optison) was tested using harmonic color Doppler at 3 MHz on a Toshiba Powervision 8000 scanner imaging the kidney. Finally, aqueous solutions with elevated CO2 were placed in the bladder and microbubbles generated using a 10 s application of 1.18 MHz ultrasound (25 cycle bursts with 0.5% duty factor and 8.4 MPa). Bubbles were detected in the kidney on two occasions with strong color Doppler signal, near that from dilute Optison. Methods can naturally produce evelated CO2, and contrast bubbles should be producible transcutaneously for reflux diagnosis without ionizing radiation and catheterization. [Work supported in part by a USPHS grant 2 RO1DK42290.]
High frequency backscatter and attenuation measurements of porcine red blood cell suspensions between 30 and 90 MHz
Authors: Maruvada Subha , Shung K. Kirk , Wang Shyh-Hau
Published: February 2014

There are now diagnostic ultrasonic imaging devices that operate at very high frequencies (VHF) of 20 MHz and beyond for clinical applications in ophthalmology, dermatology, and vascular surgery. To be able to better interpret these images and to further the development of these devices, knowledge of ultrasonic attenuation and scattering of biological tissues, such as blood, in this high-frequency range is crucial. VHF experiments were performed on porcine red blood cell (RBC) suspensions, which have been used in ultrasound experiments by many investigators but in a lower frequency range. Attenuation and backscatter from various hematocrit levels (6%, 10%, 15%, 20%, 25%, 30%) from 30 to 90 MHz were measured using focused transducers. The dependence of the attenuation coefficient from all suspensions followed linearly while the backscatter coefficient for low hematocrit suspensions was found to be a maximum between 10% and 15%. The higher hematocrits showed a decrease in their frequency dependence, possibly no longer indicating Rayleigh scattering since the wavelength is not much larger than the size of a porcine RBC. These results as well as the frequency limits of these type of scattering experiments will be discussed.
Scattering by a red blood cell: the importance of particle shape and orientation
Authors: Coussios Constantin-C. , Ffowcs Williams John E.
Published: February 2014

Red blood cells, which normally present themselves as biconcave discs, have traditionally been modeled as spherical scatterers of equivalent volume. The simplicity and symmetry of the spherical model does not however account for the effect of the angle of incidence of the incident field onto the red blood cell. Intuition tends to suggest that the field scattered by an asymmetric particle would differ if the particle were impinged upon broad-side or thin-side, an effect that is likely to become important if a collection of scatterers are aligned in any particular plane. Our objective is to compare the scattering by a red blood cell of given volume modeled as a sphere, to the result obtained by approximating its shape as a disc of varying aspect ratio. Results strongly suggest that the spherical model provides a good description for frequencies up to 20 MHz, beyond which particle shape becomes important. Although this effect could go undetected if the scattered field is only measured at angles of 180° (backscattering) and 90° relative to the direction of the incident field, the importance of particle shape and orientation might nevertheless form the base of a novel detection technique.
Ultrasonic characterization of proteins in complex fluids
Authors: Valdez Donato , Gindre Marcel , Lehuerou Jean-Yves , Waks Marcel , Urbach Wladimir
Published: February 2014

Our aim is the study of the physicochemical protein properties (volume, compressibility) as a function of hydration by an ultrasonic technique. For this purpose, we have used a biomimetic medium: reverse micelles, a system where we can control precisely water concentration. The compressibility of a medium is obtained by measuring the density and the ultrasonic celerity. The difficulty is increased in a complex fluid: nanometric size inclusions (micelles) dispersed in an organic solvent. To reach this goal, we have custom-built in our laboratory an apparatus allowing the determination of ultrasonic celerity, in very small volumes, with a relative precision of about 10 ppm. Using the effective medium theory, we have determined the compressibility of these inclusions with a precision better than 1%. With a spherical model for micellar inclusions and with the hydrodynamic radius of micelles obtained by x rays, we have estimated the compressibility of the water within micelles. We have also evidenced a difference in compressibility between the central core water and water bound to the polar surfactant headgroups. Finally by applying the mean field theory, we have obtained an estimate of the compressibility of proteins inserted within the micelles, at various hydration levels.
A hybrid model to simultaneously determine ultrasound wave velocity and thickness of multilayered media
Authors: Sousa Ana V. G. , Pereira Wagner C. A. , Machado Joo C.
Published: February 2014

This work presents a method to simultaneously obtain the wave velocity (wv) and layer thickness (h) in a stratified media, in order to generate a parametrical image. The influence of refraction is also measured and included in the propagation model. In biomedical ultrasound (US), this certainly would help diagnostic procedures, as it identifies different tissues that conventional US cannot discriminate, like benign cysts from malignant tissue. It can also be applied to determine the degree of corrosion of metal ducts and delamination of aircraft painting. The model is based on geometrical acoustics and uses two transducers to obtain experimental data (256 echoes per layer): one active (3.4 MHz) and a hydrophone, which is moved laterally through 15 positions and rotated. A two-layered phantom (alcohol 6.2 mm and acrylic 6.0 mm) is immersed in a water tank and insonified. The echoes are captured and processed using a cross-correlation-based method. The water layer parameters (wv and h) have an accuracy of 1% rms and 2% for precision; alcohol layer, 4% and 9%; and acrylic layer, 12% and 15%, respectively. The experimental results demonstrate that the model has potential to be investigated and will be applied to in vitro data.
New sonar concepts and the sensor-related developments they require
Authors: Houston Brian , Bucaro Joseph
Published: February 2014

Recently, exciting new approaches to the underwater vehicle acoustic sensing problem have been proposed which, if realized, could revolutionize how we approach underwater sonar. Two such schemes are the so-called ‘‘virtual sonar’’ which is formulated around Helmholtz integral processing and ‘‘wireless’’ systems which transfer sensor information through radiated rf signals. The full implementation of such new conceptual approaches, while presenting exciting possibilities, will nevertheless require a number of sensor-related technology advances. In this presentation, we will discuss those sensors and sensor-related developments which are desired or required in order to make practical such new sensor system concepts, and we will indicate the status of such developments. Finally, we will present several underwater applications from the perspective of exploiting these new sonar concepts. [Work supported by ONR.]