bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of the effect of signal amplitude on twinkling artifact.
Authors: Lu Wei , Cunitz Bryan W. , Sapozhnikov Oleg A. , Kaczkowski Peter J. , Kucewicz John C. , Owen Neil R. , Bailey Michael R. , Crum Lawrence A.
Published: July 2011

Twinkling artifact on color Doppler ultrasound is the color labeling of hard objects, such as kidney stones, in the image. The origin of the artifact is unknown, but clinical studies have shown that twinkling artifact can improve the sensitivity of detection of stones by ultrasound. Although Doppler detection normally correlates changes in phase with moving blood, here the effect of amplitude on the artifact is investigated. Radio-frequency and in-phase and quadrature (IQ) data were recorded by pulse-echo ensembles using a software-programmable ultrasound system. Various hard targets in water and in tissue were insonified with a linear probe, and rectilinear pixel-based imaging was used to minimize beam-forming complexity. In addition, synthesized radio-frequency signals were sent directly into the ultrasound system to separate acoustic and signal processing effects. Artifact was observed both in onscreen and post-processed images, and as high statistical variance within the ensemble IQ data. Results showed that twinkling artifact could be obtained from most solid objects by changing the Doppler gain, yet signal amplitude did not have to be sufficiently high to saturate the receive circuits. In addition, low signal but high time gain compensation created the largest variance. [Work supported by NIH DK43881, DK086371, and NSBRI through NASA NCC 9-58.]
Autoregressive ultrasound imaging method to enhance kidney stone twinkling and suppress blood flow.
Authors: Kucewicz John C. , Cunitz Bryan W. , Dunmire Barbrina , Bailey Michael R. , Crum Lawrence A.
Published: July 2011

“Twinkling” is a widely reported ultrasound artifact whereby kidney stones and other similar calcified, strongly reflective objects appear as turbulent, flowing blood in color and power Doppler. The twinkling artifact has been shown to improve kidney stone detection over B-mode imaging alone, but its use has several limitations. Principally, twinkling can be confused with blood flow, potentially leading to an incorrect diagnosis. Here a new method is reported for explicitly suppressing the display of color from blood flow to enhance and/or isolate the twinkle signal. The method applies an autoregressive model to standard Doppler pulses in order to differentiate tissue, blood flow, and twinkling. The algorithm was implemented on a software-based, open architecture ultrasound system and tested by a sonographer on phantoms and on stones implanted in a live porcine kidney. Stones of 3–10 mm were detected reproducibly while suppressing blood flow in the image. In conclusion, a new algorithm designed to specifically detect stones has been tested and has potential clinical utility especially as efforts are made to reduce radiation exposure on diagnosis and monitoring. [This work was supported by the National Institutes of Health (NIH Grant No. DK43881) and the National Space Biomedical Research Institute through Grant No. NASA NCC 9-58.]
Modeling of radiation force imparted to an elastic sphere from an ultrasound beam of arbitrary structure.
Authors: Sapozhnikov Oleg A. , Bailey Michael R.
Published: July 2011

The radiation force created by an acoustic wave incident on an elastic sphere is studied theoretically. Elastic spheres with properties similar to kidney stones are considered. An acoustic wave is taken in the form of a high-intensity focused ultrasound beam of megahertz frequency, which is typical for transducers proposed for stone therapy. To study radiation force of beams with arbitrary structure, the source excitation is modeled as a sum of plane waves of various inclinations (angular spectrum representation). First, a plane acoustic wave scattering at the stone is modeled using the known solution in the form of a spherical harmonics series. Then superposition of such solutions is used to calculate the scattered field from a focused beam. Once the acoustic field is known, the radiation stress tensor is calculated on a surface surrounding the sphere. Finally, the net force acting on the sphere is calculated by integrating the radiation stress along the surface. Numerical calculations show that the direction and value of the radiation force acting on the sphere depend on the pressure field structure in the region where the scatterer is positioned. [Work supported by NIH DK43881 and DK086371, RFBR, and NSBRI through NASA NCC 9-58.]
Real-time tracking of renal calculi displaced by the radiation force of focused ultrasound.
Authors: Illian Paul R. , Cunitz Bryan W. , Kucewicz John C. , Bailey Michael R. , Kaczkowski Peter J.
Published: July 2011

An area of active research involves using the radiation force of ultrasound to expel small kidney stones or fragments from the kidney. The goal of this work is real-time motion tracking for visual feedback to the user and automated adaptive pushing as the stone moves. Algorithms have been designed to track stone movement during patient respiration but the challenge here is to track the stone motion relative to tissue. A new algorithm was written in MATLAB and implemented on an open-architecture, software-based ultrasound system. The algorithm was first trained then implemented in real-time on B-mode IQ data recorded from phantom experiments and animal studies. The tracking algorithm uses an ensemble of image processing techniques (2-D cross-correlation, phase correlation, and feature-edge detection) to overlay color on the stone in the real-time images and to assign a color to indicate the confidence in the identification of the stone. Camera images as well as ultrasound images showed that the system was able to locate a moving stone, re-target, and apply a new focused push pulse at that location. [Work supported by NIH DK43881, NIH DK086371, and NSBRI through NASA NCC 9-58].
Stress waves in kidney stones.
Authors: Luo Haibiao , Cleveland Robin O.
Published: July 2011

A 3-D time-domain finite-difference solution to the linear elastic equations was applied to investigate the stress and velocity fields of kidney stones subject to lithotripsy shock waves. The kidney stone models were scanned from micro-computed tomography and had diameters from 2 to 5 mm. It was found for these shapes that shear waves induced by interference of the shock wave with stone boundaries dominated the high stress in the stones. The traditional belief of stone comminution mechanism by spall mechanism does not play important role due to the irregular proximal and distal stone surfaces. It was found for natural stones that stone orientation had an impact on the generation of high stress with a smooth convex surface producing the highest internal stresses. The results indicate that lithotripters with a focal width larger than a stone should be able to break a stone more efficiently since the large focal width shock waves result in stronger interaction with stone circumferences and produce larger shear waves.
A theory-based model of the prevalence of transportation noise annoyance.
Authors: Fidell Sanford , Schomer Paul , Mestre Vincent
Published: July 2011

Dosage-response relationships between cumulative noise exposure and the prevalence of annoyance in communities are generally developed by statistical curve fitting methods. Generic methods of this sort, such as regression, can characterize the central tendency of findings of social surveys, but provide no explanation for the great variability of these data. Further, confidence intervals around a regression curve do not yield prediction intervals appropriate for use in environmental disclosure documents. An alternative approach under consideration by ISO Working Group 45 for inclusion in an updated draft international standard is based on the hypothesis that the rate of growth of the prevalence of annoyance closely resembles that of the rate of growth of effective (that is, duration-corrected) loudness. A comprehensive database of the findings of 43 aircraft noise annoyance studies provides strong empirical support for the hypothesis.
A simple method for comparing social survey findings on the annoyance of transportation noise.
Authors: Mestre Vincent , Schomer Paul , Fidell Sanford
Published: July 2011

Findings of social surveys about the annoyance of transportation noise vary greatly from one community to the next. Popular speculations about the sources of this variability have included situational differences in exposure, methodological differences in interviewing, and errors of measurement. The model described in the prior presentation provides a simple method for summarizing the community-specific variability in a single-valued metric, the community tolerance Index (CTI). Findings of several CTI-based analyzes are discussed in this presentation, along with some of their policy and regulatory implications.
A new metric for the objective determination of steady state noise source measurement validity as affected by extraneous noise.
Authors: Hart Noel W. , Bruce Robert D. , Galetti Ralph R. , Rubino Mark
Published: July 2011

The measured difference between the maximum sound level (Lmax) and the equivalent sound level (Leq) of a steady state source can be used to objectively demonstrate inconsistencies in measurement. This method has particular applications to field measurements made in an uncontrolled environment where extraneous, time-variant noise from wind, animals, people, or machinery often interferes. The method is also straight forward to implement with modern sound level meters, as the necessary data are easily recorded.
Directivity and variability characterization of a propane cannon.
Authors: Noble Tom W. , Valente Dan P.
Published: July 2011

When studying the influence of an environment on blast noise propagation, it is often unrealistic to use typical blast noise sources such as plastic explosives or artillery fire. A propane cannon, designed as a bird scare-away device, is a reasonable surrogate source which produces a loud impulsive sound rich in low frequency energy. In order to confirm the cannon’s utility as a blast surrogate, we examined the directivity of the propane cannon, the variability in received level as a function of distance, and the variability in one-third octave band SEL as a function of distance and direction. The results indicated that the propane cannon has low shot-to-shot variability and is nearly omni-directional within 60 deg of the forward facing direction.
The acoustic levitation and simultaneous contactless transportation of matter in the third resonance mode (H3-mode) of a line-focused system.
Authors: Foresti Daniele , Nabavi Majid , Poulikakos Dimos
Published: July 2011

We investigate theoretically herein higher modes of resonance for transportation of matter (particles or droplets) in line-focused acoustic levitation. Contactless transportation was achieved by varying the height between the radiating plate and the reflector. Transportation and levitation of volatile liquids, in particular, involves two limits of the acoustic forces. The lower limit corresponds to the minimum force required to levitate a droplet, i.e., to overcome the gravitational force. The higher limit corresponds to the maximum acoustic pressure before atomization of the droplet occurs. By increasing the size of the droplet, the lower limit increases and the higher limit decreases. Therefore, in order to have large droplets levitated in the device, a relatively flat radiation pressure over the translation distance is needed. In this study, using a finite element model, the Gor’kov potential was calculated for different heights between the reflector and the radiating plate. It was found that the best levitation configuration is the H3-mode, which represents a good compromise between high levitation power and smooth pattern transition. The H3-mode also allows three translation lines in parallel.
Manipulating 5 nanometer diamond nanoparticles in user-defined patterns using bulk acoustic waves.
Authors: Raeymaekers Bart , Pantea Cristian , Sinha Dipen N.
Published: July 2011

We investigate manipulating 5 nm diamond nano-particles in a user-defined pattern on a substrate using the acoustic radiation force associated with a bulk acoustic standing wave. Both concentric and rectangular patterns are studied and the experimental results are compared with theoretical predictions. The effect of drag force acting on a nanoparticle is evaluated and limits for particle speed and particle size that can be moved by acoustic radiation force are determined. The importance of Brownian motion when manipulating nanoparticles is discussed. We found good agreement between our experimental results and existing theoretical models and demonstrate that nano-sized particles can be manipulated effectively by means of bulk wave acoustic radiation force.
Metamaterial synthesis using the acoustic radiation force and characterization with x-ray microcomputed tomography.
Authors: Mitri F.G. , Sinha D.N.
Published: July 2011

In this research, we demonstrate the manipulation of clusters of ∼5 nm-diameter carbon nano-particles using the acoustic radiation force at 1 and 2 MHz. 1-D and 2-D patterns are synthesized and experimental results show the successful synthesis of a nano-composite 3D metamaterial structure. Furthermore, x-ray micro-computed tomography (CT) is used as a tool to charaterize each metamaterial. Though not investigated here, the aim is to create finite element models based on the x-ray micro-CTs to study the multiple functionalities of the acoustically-assembled metamaterials. [Work supported by LANL-LDRD X9N9.]
Arbitrary acoustic scattering of a high-order Bessel vortex beam by a sphere.
Authors: Mitri F. G.
Published: July 2011

The arbitrary acoustic scattering of a high-order Bessel vortex beam by a sphere is investigated. It is shown here that shifting the sphere off of the axis of wave propagation induces a dependence of the scattering on the azimuthal angle. Theoretical expressions for the incident and scattered fields from a rigid immovable sphere are derived. The near- and far-field acoustic scattering fields are expressed using partial wave series involving the mth-order spherical harmonics, the scattering coefficients of the sphere, the half-conical angle of the wave number components of the beam, its order, and the beam-shape coefficients. The scattering coefficients of the sphere and the three-dimensional (3-D) scattering directivity plots in the near- and far-field regions are evaluated using a numerical integration procedure. The calculations indicate that the scattering directivity patterns near the sphere and in the far-field are strongly dependent on the position of the sphere facing the incident high-order Bessel vortex beam. In addition to providing physical insight into the off-axial scattering of acoustic Bessel vortex beams, this investigation would potentially assist in the development of the transverse acoustic radiation force and could provide a useful test of finite element codes for the evaluation of the scattering.
Modal exchange between an elastic mode and an acoustic mode of a fluid-filled spherical shell resonator at an avoided crossing.
Authors: Lonzaga Joel B. , Mobley Joel , Gaitan D. Felipe
Published: July 2011

High pressure liquid-filled spherical resonators are promising devices for increasing the energy density of a cavitating liquid. Since increasing the static pressure in the liquid also increases the sound speed, it is important to investigate the dependence of the resonances on the sound speed. In this paper, we report on an avoided crossing or repulsion between an elastic mode and an acoustic mode of a fluid-filled spherical shell resonator as the sound speed is varied. Such an avoided crossing is attributed to the fluid-shell interaction and leads to a modal exchange between the acoustic and the elastic modes. Furthermore, the eigenfrequency curves of both the acoustic and elastic modes are discontinuous in the frequency-sound speed phase space in the neighborhood of the avoided crossing. Additional analysis reveals that the elastic mode also forms an avoided crossing with other acoustic mode orders and that this result can be extended to other pairs of modes with different symmetry. The acoustic pressure field in the fluid and the stress field in the shell are shown to take extreme values at this region. [Work supported and funded by Impulse Devices, Inc. ACPT Contract No. W9113M-07-C-0178.]
Measurement of the penetration depth for an ultrasonic diffraction grating in contact with a slurry.
Authors: Greenwood Margaret S.
Published: July 2011

The initial measurements of the penetration depth were presented at the Portland ASA meeting [Proceedings of Meetings in Acoustics, Vol. 6 P.045001]. This report describes additional measurements using several gratings with transducer frequencies of 1, 3.5, and 7 MHz. The grating unit (with the grating surface in the horizontal plane) is placed atop a vessel containing a slurry of polystyrene spheres in water. The data acquisition system was set up to take up to 20 measurements of the FFT amplitude per second. When the magnetic stirrer is turned off, the increasing FFT amplitude shows the transition from a slurry to water as the particles fall to the bottom of the vessel. As the slurry descends it forms a layer which is videotaped to yield the descent velocity. The penetration depth is obtained from the transition time and the descent velocity. The penetration depth varies with frequency and is less than about 4 mm. These measurements were not taken at the critical frequency for which the penetration depth is expected to be very large.
Numerical simulation of acoustic wave interaction with inhomogeneous elastic bodies containing homogeneous inclusions.
Authors: Bleszynski Elizabeth , Bleszynski Marek , Jaroszewicz Thomas
Published: July 2011

An extended version of the previously developed volumetric integral equation solver is presented, which is based on solving a coupled system of volumetric and surface equations describing, respectively, the inhomogeneous elastic object and the embedded piecewise homogeneous inclusions. The considered method is capable of accurate large-scale numerical simulations involving anatomically realistic models of a human head characterized by complex geometrical details and large density contrasts. The main application of the approach consists in an accurate analysis of interaction of acoustic waves with human hearing system; in this case, precise modeling of the highly intricate structure of middle and inner ears is essential for reliable numerical simulations capable of discerning between different mechanisms of energy transfer to the human ear. The method allows us to treat the inner ear region as a piecewise homogeneous inclusion described by surface integral equations with displacement and traction fields as unknowns. The results of representative calculations will be presented, which were carried out with a realistic detailed geometry model of the middle and inner ear including essential geometry elements needed in simulating energy transfer processes. [This work is supported by the AFOSR.]
Four-chamber cochlea box model: Establishing acoustic comfort, illustrating injury and toward therapy.
Authors: Bo-ot Luis Ma. T. , Lee Henry V. , Ramos Henry J. , Chiang Che-Ming
Published: July 2011

The unrolled cochlea is modeled using the finite-element software ANSYS with four inner chambers representing the Scala Vestibuli contiguous with the Scala Tympani thru a rounded helicotrema, the Scala Media, the inner and the outer hair cells. The tectorial membrane is represented as a plate in contact with the hair cells. An improvement from previously presented results is the inclusion of a tapered helicotrema. Various geometries are compared, i.e. with straight sides and with tapered sides, and differences in the frequency response of the models are seen. Applying real values for material properties and the human hearing range and using characteristic frequency at certain nodes inside the Scala Media, the tapered model is calibrated to establish the reference comfort sound level. Hearing injury is regarded by subjecting nodes to increased sound pressure levels until the frequency response disappears. This is done at the same time monitoring the change in electrical potential in the inner and outer hair cell regions. The potential change between the normal and the injured conditions is inputted to the Gibbs energy equation for the ATP-ADPase glycolysis to identify a possible route to remedy.
Synchrony-capture filterbank: A novel cochlear signal processing model.
Authors: Kumaresan Ramdas , Peddinti Vijay , Cariani Peter
Published: July 2011

Examination of the representation of low harmonics of complex sounds in the auditory nerve shows a striking feature known as “synchrony capture.” Fibers of an entire cochlear region are driven almost exclusively by one local, dominant harmonic component [Delgutte and Kiang, 1984]. Sharp boundaries characteristic of such synchrony capture are also seen between the different CF regions driven by different dominant, formant-region harmonics for multiformant vowels. Based on this observation, we propose a model for peripheral processing, which is not just a filter bank but behaves more like signal adaptive receivers. We call this model synchrony capture filterbank (SCFB). SCFB consists of a traditional gammatone filterbank, the individual filters of which are then cascaded with a bandpass filter (BPF) triplet. The BPF triplet is an adaptive tone follower and consists of three overlapping bandpass filters whose center frequencies can be changed using feedback. The amplitudes at the output of the the bandpass filters are feedback to tune the BPF triplet such that it centers itself on top of the dominant tone in the input signal. The SCFB exhibits the synchrony capture behavior that is observed in real auditory nerve fibers.
Cortical neural coding of speech in simple and complex auditory scenes.
Authors: Ding Nai , Simon Jonathan Z.
Published: July 2011

The neural representation of continuous speech in human auditory cortex was obtained noninvasively via magnetoencephalography. The neural response was recorded from human subjects listening to a spoken narrative, either in clean or in the presence of interfering speech. The cortical neural response to clean speech is demonstrated to precisely track the slow temporal modulations (<10 Hz) of speech in a broad spectral region between 400 Hz and 2 kHz. The neural code is sufficiently faithful to decode acoustic features of speech. To examine the robustness of, and the role of attention in, this neural code, another spoken narrative was presented simultaneously, either to a different ear (dichotically) or to the same ear (diotically), instructing the subjects to focus on only one of the two speech signals. The cortical representation of the attended speech is found to be substantially stronger than that of the unattended speech. This attentional effect is significant during the subjects’ first exposure to the spoken narratives. These results demonstrate that auditory cortex precisely represents the slow temporal modulations of speech and maintains separate neural representations for concurrent speech signals that can be individually and strongly modulated by attention. [Work supported by the NIDCD Grant No. R01-DC-008342.]
Relationships linking age, selective attention, and frequency following in the brainstem.
Authors: Ruggles Dorea R. , Shinn-Cunningham Barbara G.
Published: July 2011

Several studies have demonstrated that increasing age leads to a decrease in the ability of the brainstem to phase-lock to periodic stimuli. This frequency following response has additionally been related to several other metrics, including musical training, experience with a tonal language, and ability to understand speech in noise. The current study explored a potential relationship between brainstem responses and large, observed individual differences in the ability of normal-hearing listeners to deploy selective spatial auditory attention. Previously, we reported that the ability to selectively attend varies enormously (from near chance to 90% correct) in normal-hearing listeners, but is uncorrelated with age (ranging from 20–55 years). Here, we recruited a subset of the original listeners and measured the brainstem’s frequency-following response (FFR). Although selective-attention performance was correlated with the strength of the FFR, there was an interaction between the FFR strength and age. For younger listeners, the FFR closely predicted selective attention ability, but the FFR was weak in all older listeners, even those who performed well behaviorally. These results show that the FFR strength decreases with age without necessarily leading to degraded perceptual abilities; however, young listeners with weak FFR cannot effectively deploy selective spatial attention.
Across-ear integration of complex speech stimuli.
Authors: Brungart Douglas S. , Iyer Nandini , Simpson Brian D
Published: July 2011

In listening environments with spatially separated sources, listeners can often obtain a substantial improvement in performance by implementing a “better ear” listening strategy where they selectively attend to the ear with the more advantageous signal to noise ratio (SNR). However, relatively little is known about the ability of listeners to implement the better ear strategy on a band-by-band basis by focusing attention on a different ear within each frequency band. This experiment examined how efficiently listeners are able to implement a band-by-band better-ear listening strategy by dividing a modified rhyme test speech stimulus into 20 frequency bands of approximately equal intelligibility and presenting a subset of those bands either monaurally, with all the bands in one ear, or dichotically, with half the bands assigned to one ear and half assigned to the other ear. The results showed that the listeners were able to integrate information across the two ears on a band-by-band basis, and that this ability was robust in a wide range of within-band and across-band masking conditions. However, there was a slight penalty for dichotic presentation, which was estimated to be roughly equivalent to a 1.2 dB decrease in the SNR of a broadband speech signal in noise.
The effect of disrupting the continuity of target sentences on the perceptual segregation of competing voices.
Authors: Iyer Nandini , Brungart Douglas S. , Simpson Brian D.
Published: July 2011

Relative differences in fundamental frequency and prosodic features have been studied as possible cues that enable listeners to segregate a target talker in multitalker listening tasks. However, little is known about the effects of disrupting the prosody characteristics of a talker within a single phrase. The current experiment measured color-number keyword identification scores with the coordinate response measure (CRM) sentences under two conditions: a “normal prosody” condition, where the target and masker phrases were spoken contiguously by a single talker, and a “disrupted prosody” condition, where the target and masking phrases were generated by concatenating together individual words that were originally spoken in different sentences. The results show that the elimination of normal prosodic cues had the greatest impact on performance when the target sentence was masked by a single CRM masking phrase that was presented at the same level as the target talker. The elimination of prosodic information had only a very slight impact on performance when the target talker was masked by more than one simultaneous talker, suggesting that the use of prosodic cues for segregation may be impaired when more than one interfering talker is present in the mixture.
Predicting speech intelligibility based on the envelope power signal-to-noise ratio after modulation-frequency selective processing.
Authors: Dau Torsten , Jo/rgensen So/ren
Published: July 2011

A model for predicting the intelligibility of processed noisy speech is proposed. The model represents a speech-based version of the envelope power spectrum model [Ewert and Dau, 2000] originally developed to account for modulation detection and masking data. The model estimates the ratio of speech-to-noise envelope power, SNRenv, at the output of a modulation filterbank and relates this metric to speech intelligibility using the concept of an ideal observer. Model predictions were compared to literature data, obtained with speech mixed with stationary speech-shaped noise. Furthermore, the model was tested in conditions with noisy speech subjected to reverberation and spectral subtraction. Consistent with new experimental data, the model predicted an increase in SRT as a function of the reverberation time as well as in conditions of spectral subtraction, the latter in contrast to the STI. An analysis of the model’s internal representation of the stimuli processed by spectral subtraction revealed that the decrease of the predicted speech intelligibility was caused by an elevation of the noise envelope power, which exceeded that of the speech envelope power. The results strongly suggest that the signal-to-noise ratio at the output of modulation frequency selective processing represents a critical measure of speech intelligibility.
Temporal integration of interrupted speech: Effects of time compression and expansion on the intelligibility of words and sentences.
Authors: Shafiro Valeriy , Sheft Stanley , Risley Robert
Published: July 2011

Temporal integration of interrupted speech was investigated by contrasting the performance on gated to time-compressed/expanded words and sentences. In the control condition, HINT sentences and CNC words were gated at 0.5, 1, 2, 4, 8, or 16 Hz using a 50% duty cycle. In the two experimental conditions, stimuli previously gated at each rate were either time-compressed by concatenating the consecutive speech segments or time-expanded by doubling the silent intervals between consecutive speech segments. Across rates, these manipulations thus varied both the size of intact speech intervals and the duration of silence between the intervals. No differences were observed in the rate-intelligibility functions of gated versus time-expanded words and sentences with the overlapping functions monotonically rising with rate. Though intelligibility was similar to the gated control condition at the lower and higher rates, the time-compressed rate-intelligibility function for sentences was nonmonotonic with a minimum at 2-Hz. In contrast, the time-compressed function for words remained similar to the corresponding gated and time-expanded functions. These findings indicate that the temporal integration of interrupted speech takes places on different perceptual time scales for words and sentences and is affected by the size of speech segments being integrated. [Work supported by NIH/NIDCD.]
Experimental and computational studies of vortex shedding and aerodynamic sound for flow over a square cylinder near a rigid wall.
Authors: Hu Yatao , Chen Jun , Li Kai Ming , Hu Yatao , Wu Keqi
Published: July 2011

Flow around a bluff body near a solid wall, such as a circular or rectangular cylinder placed in a uniform flow near a solid boundary, is of fundamental importance. The reduction in the aerodynamic sound is a very important issue, for example, flow induced noise in tall buildings, bridges, high-speed trains, windmills, and computer cooling fans. This type of problem has been addressed extensively both experimentally and theoretically in the past. The flow past a long rectangular cylinder is usually associated with vortex shedding, which can be affected strongly by the presence of a nearby wall. Flow past a solid body induces vortices and the vortex acceleration will cause sound. In the present study, the aerodynamic sound generated by flow past a rectangular cylinder of various configurations was investigated experimentally in a low-speed quiet wind tunnel. A numerical study using large scale eddy Simulation technique has also been conducted to compute the sound generation due to vortex shedding. Experimental results are compared with the numerical predictions. [Work sponsored by the China Scholarship Council.]
SALINAS: A massively parallel finite element code for structural dynamics and acoustic analysis.
Authors: Rouse Jerry W. , Walsh Timothy F. , Reese Garth M.
Published: July 2011

This talk shall present an overview of SALINAS, a massively parallel finite element code for structural dynamics and acoustics analysis that is being developed at Sandia National Laboratories. SALINAS allows for prediction of both the time and frequency domain responses of complex structural, acoustic, and fully coupled structural acoustic systems having millions of degrees of freedom. An overview of SALINAS capabilities shall be presented including development history, solver and element types, quadratic eigenanalysis and frequency response, direct frequency response, nonlinear acoustics, implicit transient dynamic analysis, and infinite elements with focus given to structural acoustics capabilities. The application of SALINAS to structural acoustics problems shall also be presented as well as future directions of research for the development of the code.
On the use of a variational boundary element/finite element approach to predict the vibroacoustic response of structures.
Authors: Sgard Franck , Amichi Kamel , Atalla Noureddine , Nlisse Hugues
Published: July 2011

This paper deals with the application of a variational boundary element/finite element approach to predict the vibroacoustic response of structures. First, the theoretical formulation is presented. Then two specific examples are considered and numerical results are presented. The first case concerns the calculation of the sound transmission through a curved orthotropic sandwich panel. The blocked pressure field acting on the structure is first calculated and then used as a loading in the computation of the forced response of the panel. The second case consists of the calculation of the sound radiation of an assembly of plates at different angles excited by uncorrelated point forces. This configuration is of special interest to evaluate the accuracy of analytical Leppington’s radiation efficiency correction factors related to baffle angles to predict the acoustic power radiated by a box-shaped acoustic enclosure.
Low-frequency geoacoustic modeling in shallow water sediment environments.
Authors: Chapman N. Ross
Published: July 2011

The goal in geoacoustic modeling is to develop realistic geophysical models of the ocean bottom that can be used in numerical calculations of the acoustic field in the ocean. The ocean bottom is assumed to be a layered structure of different types of sediment material that have been deposited over geological times. However, in shallow water the bottom is generally much more complex. The sediment material is variable on different spatial scales horizontally and is inhomogeneous in depth below the sea floor. Despite this complexity in realistic bottom environments, there has been considerable success using the simplified approach of a layered, range-independent geology in low-frequency (20–500 Hz) applications with inversion techniques that provide estimates of geoacoustic model parameters and their uncertainties. This paper reviews some of the most effective inversion techniques and compares their performance in estimating realistic and effective geoacoustic profiles in applications with data from the recent Shallow Water ‘06 experiments on the New Jersey continental shelf. Conditions are discussed that limit the performance of present day inversion techniques. These include rough interfaces on and below the sea floor, consolidated material that supports shear wave propagation, and range variation of sub-bottom structure.
Practical applications and limitations for analog auralizations.
Authors: Vedvik Richard A.
Published: July 2011

Developing auralizations of irregularly shaped or small spaces proves to be a challenge for computer software to achieve a natural representation of the original recording. Analog auralizations are discussed using scaled wavelengths, high-bandwidth loudspeakers, and high-bitrate and high-bandwidth measurement equipment, effectively capturing the sound of the analog room. This paper discusses the practical applications and limitations of scale model analog acoustic auralizations. Impulse responses and auralizations of anechoic musical performances in a 1:5 scale music practice room are presented to demonstrate the fine tuning capability of the technique. Interference from outside sources such as ultrasonic emissions of modern electronics is also discussed.
Acceleration of acoustic raytracing using graphics processors.
Authors: Cheng Zuofu , Haken Lippold
Published: July 2011

OpenCL presents an industry standard interface to accelerate computationally expensive algorithms on consumer grade graphics hardware. Presented is a system in which raytracing for room acoustic simulation is accelerated with OpenCL. The system is primarily geared toward realtime applications such as video gaming or virtual reality, but may be extended to higher quality simulations for architectural acoustics. Different methods for mapping the raytracing problem onto the GPU are discussed, as well as strategies for optimizing the algorithm for graphics processors from different manufacturers.
Efforts to improve the acoustics requirements in the proposed International Green Construction Code.
Authors: Stewart Noral D.
Published: July 2011

In the spring of 2010 the acoustics community became aware of a proposed set of acoustical requirements in the International Green Construction Code being developed by the International Codes Council. The acoustics section as proposed contained many problems. Several members of the Acoustical Society of America submitted comments pointing out the problems and suggesting changes or recommending that action be delayed until appropriate changes could be developed. The ICC accepted only a few of the comments submitted for inclusion in the next draft. Subsequently, a member of the ICC committee that reviewed the comments offered to help with comments on the new draft and suggested that what the ICC needed was a recommendation endorsed by the acoustical community. An effort was made to develop a recommendation endorsed by various organizations involved in acoustics to be submitted in early January 2011. This paper will discuss the original ICC proposal, the efforts to change it, the changes proposed, and the results if known of the hearings to be held the week before the ASA Seattle meeting.
Terminology and conceptual frameworks for cumulative effects analysis.
Authors: Gisiner Robert , Simmons Samantha
Published: July 2011

In the short history of underwater noise regulation most efforts have focused on the risk posed by a single source over a short period. However, noise in the workplace, cityscape, and terrestrial environment are typically expressed in terms of the cumulative consequences of repeated exposures from multiple sources over long periods. Recent publications and workshop reports on cumulative effects’ analysis are reviewed, and a terminology and conceptual approach are proposed to facilitate analysis of the cumulative effects of underwater noise. The term cumulative effect is reserved for the accretion of effects over time while the term aggregate effect is proposed for the effect of multiple concurrent stressors, both acoustic and nonacoustic. Possible metrics for comparing effects across individual stressors are discussed, including measures of caloric cost and physiological stress. A modeling framework is proposed, by which the synergistic effect of combined stressors might be quantitatively assessed.
A bioenergetics approach to understanding the population consequences of acoustic disturbance.
Authors: Costa Daniel P. , Schwarz Lisa K. , Robinson Patrick W.
Published: July 2011

[A major hurdle with marine mammal conservation and management is to know if and when measurable short term responses result in biologically meaningful changes in populations. We are developing a bioenergetics approach to parametrize the transfer functions developed in the conceptual model developed by the NRC Committee on the population consequences of acoustic disturbance (PCAD). Our effort is directed at quantifying the life functions that are linked to vital rates, and how changes in these vital rates affect populations. Such an approach can identify species and or particular life history characteristics that are likely to be sensitive or resilient to acoustic disturbance. Using species that represent the range of life history patterns observed in marine mammals we are analyzing the existing data to determine whether there is a linkage between fine scale measurements of foraging behavior and reproductive success and survival. These data are being used to develop a time-activity budget to produce a first order quantitative assessment of the potential significance in terms of lost energy and/or time that foraging behavior or habitat utilization is potentially affected by acoustic disturbance.
Assessing long-term impacts of vocal compensation to ambient noise by measuring the metabolic cost of sound production in bottlenose dolphins.
Authors: Noren Dawn P. , Holt Marla M. , Williams Terrie M.
Published: July 2011

The use of sound is essential to the survival of cetaceans. Therefore, anthropogenic sound exposure is a concern. Cetaceans can change the amplitude, duration, repetition rate, and/or frequency of sounds they produce to compensate for masking noise. Potential costs of such compensation are unknown, and no empirical data on the metabolic cost of sound production in marine mammals exist. This study aims to determine the metabolic cost of cetacean vocalizations to assess the biological significance of vocal compensation. Oxygen consumption, respiration rates, and vocalizations of two captive bottlenose dolphins were recorded during sound production at moderate levels. One dolphin produced his signature whistle while the other produced a pulsed squawk or squeaklike sound. Both types of vocalizations increased oxygen consumption while respiration rates did not change. This increased oxygen consumption is likely due to increased metabolic demand related to sound production, rather than changes in breathing patterns. Thus, acoustic signals performed in response to increased vessel presence and anthropogenic noise may increase metabolism in cetaceans. Depending on the duration and intensity of exposure, it is possible that vocal compensation responses increase total daily energy expenditure, which may impact daily prey requirements. [Study supported by the U.S. Office of Naval Research.]
Differences between natural and depredation behaviors in sperm whales (Physeter macrocephalus), using dive, acoustic, and orientation data from short-term tags.
Authors: Mathias Delphine , Thode Aaron , Straley Jan , Calambokidis John , Schorr Gregory S. , Folkert Kendall
Published: July 2011

Sperm whales depredate black cod (Anoplopoma fimbria) from demersal longlines in the Gulf of Alaska. Over a 3-year period 11 bioacoustic tags have been attached to adult sperm whales off Southeast Alaska under both natural and depredation foraging conditions. Measurements of the animals’ dive profiles, acoustic behavior, and angular velocity under both behavioral modes were distilled and examined for statistically significant differences. Two rough categories of depredation are identified. The dive depths and durations of “deep depredating” whales are similar to those of natural dives, but acoustic parameters and roll rates show significantly significant differences. By contrast, “shallow depredating” whales conduct dives that are much shorter, shallower, and more acoustically active than natural foraging dives. Acoustic “creak” rates, which serve as proxies for prey capture attempt rates, are four times greater during shallow depredation than during natural foraging. During all behaviors, whales generating creak sounds had significantly greater roll rates when the creak was followed by a pause, suggesting that acoustic monitoring might distinguish prey capture successes from failed attempts. Fish that naturally “spin-off” the line during a haul may explain facets of deep depredation. [Work supported by the North Pacific Research Board, the National Geographic Society, and OGP.]
False killer whales and Hawaii’s longline fisheries.
Authors: Oleson Erin M. , Forney Karin A.
Published: July 2011

False killer whales have been implicated in depredation, or removal of catch or bait, from pelagic longline fisheries throughout the Indo-Pacific. These interactions often result in significant financial loss to the fishing industry, and though uncommon, hooking, or entanglement of false killer whales during depredation often leads to death or serious injury of the whales. False killer whale bycatch in Hawaii’s longline fisheries exceeds allowable limits established under the Marine Mammal Protection Act. In 2010, the National Marine Fisheries Service convened a Take Reduction Team to develop a plan for reducing serious injuries and mortalities of false killer whales caused by such interactions. Means of avoiding or minimizing depredation were an important aspect of the Team’s deliberations. Among other factors, measures of noise produced by fishing vessels or gear and local acoustic propagation may help predict false killer whale-fishing gear interactions. Acoustics studies are now underway to evaluate noise produced by fishing vessels and the setting, soaking, and hauling of gear, and to evaluate the behavior of false killer whales when they interact with gear. Additional studies on echolocation jamming or acoustically disguising gear were also suggested by the Team.
The Aloha Cabled Observatory.
Authors: Van Uffelen Lora , Duennebier Fred , Lukas Roger , Howe Bruce
Published: July 2011

20 months of deep-ocean acoustic spectra have been obtained from a single hydrophone 10 m above the ocean depth of 4720 m in an initial proof phase of the Aloha Cabled Observatory (ACO), the only abyssal ocean observatory in the world. A decommissioned telecommunications cable donated by AT&T provides power and communication to the observatory, which is located approximately 100-km north of Oahu, HI, at Station ALOHA, the field site of the Hawaii Ocean Time-series (HOT) program that has collected biological, physical, and chemical oceanographic data since 1988. The Aloha Cabled Observatory will be augmented in May 2011 with a general-purpose node outfitted with two hydrophones as well as CTD, ADCP, themistor, bio-optical, and visual sensors. The ambient acoustic data from the ACO hydrophone, which was collected from February 2007 to October 2008 contemporaneously with wind, wave, and seismic data, indicate that local wind speed is the most important parameter affecting background acoustic levels, and directional characteristics of the wind-driven ocean surface wave field also strongly influence the acoustic spectra. Correlation with seismic and wave spectra implies that wave reflections from coastal waters generate seismic energy that dominate the acoustic spectrum below 0.4 Hz.