bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of perceived talker race on phonetic imitation of pin-pen words
Authors: Yan Qingyang
Published: October 2014

The current study investigated the phonetic imitation of the PIN-PEN merger by nonmerged participants. An auditory shadowing task was used to examine how participants changed their /ɪ/ and /ɛ/ productions after auditory exposure to merged and nonmerged voices. Black and white talker photos were used as visual cues to talker race. The pairing of voices (merged and nonmerged) with the talker photos (black and white) was counterbalanced across participants. A third group of participants completed the task without talker photos. Participants’ explicit talker attitudes were assessed by a questionnaire, and their implicit racial attitudes were measured by an Implicit Association Task. Nonmerged participants imitated the PIN-PEN merger, and the degree of imitation varied depending on the experimental condition. The merged voice elicited more imitation when it was presented without a talker photo or with the black talker photo than with the white talker photo. No effect of explicit talker attitudes or implicit racial attitudes on the degree of imitation was observed. These results suggest that phonetic imitation of the PIN-PEN merger is more complex than an automatic response to the merged voice and that it is mediated by perceived talker race.
Foreign-accent discrimination with words and sentences
Authors: Atagi Eriko , Bent Tessa
Published: October 2014

Native listeners can detect a foreign accent in very short stimuli; however, foreign-accent detection is more accurate with longer stimuli (Park, 2008; Flege, 1984). The current study investigated native listeners’ sensitivity to the characteristics that differentiate between accents—both foreign versus native accents and one foreign accent versus another—in words and sentences. Listeners heard pairs of talkers reading the same word or sentence and indicated whether the talkers had the same or different native language backgrounds. Talkers included two native talkers (Midland dialect) and six nonnative talkers from three native language backgrounds (German, Mandarin, and Korean). Sensitivity varied significantly depending on the specific accent pairings and stimulus type. Listeners were most sensitive when the talker pair included a native talker, but could detect the difference between two nonnative accents. Furthermore, listeners were generally more sensitive with sentences than with words. However, for one nonnative pairing, listeners exhibited higher sensitivity with words; for another, listeners’ sensitivity did not differ significantly across stimulus types. These results suggest that accent discrimination is not simply influenced by stimulus length. Sentences may provide listeners with opportunities to perceive similarities between nonnative talkers, which are not salient in single words. [Work supported by NIDCD T32 DC00012.]
Mapping bistatic scattering from spherical and cylindrical targets using an autonomous underwater vehicle in BAYEX'14 experiment
Authors: Fischell Erin M. , Petillo Stephanie , Howe Thomas , Schmidt Henrik
Published: October 2014

In May 2014, the MIT Laboratory for Autonomous Marine Sensing Systems (LAMSS) participated in the BAYEX'14 experiment with the goal of collecting full bistatic data sets around proud spherical and cylindrical targets for use in real-time autonomous target localization and classification. The BAYEX source was set to insonify both targets, and was triggered to ping at the start of each second using GPS PPS. The MIT Bluefin 21 in. AUV Unicorn, fitted with a 16-element nose array, was deployed in broadside sampling behaviors to collect the bistatic scattered data set. The AUV's Chip Scale Atomic Clock was synchronized to GPS on the surface, and the data was logged using a PPS triggered analog to digital conversion system to ensure synchronization with the source. The MIT LAMSS operational paradigm allowed the vehicle to be unpacked, tested and deployed over the brief three-day interval available for operations. MOOS-IvP and acoustic communication enabled the group to command AUV mission changes in situ based on data collection needs. During data collection, the vehicle demonstrated real-time signal processing and target localization, and the bistatic datasets were used to demonstrate real-time target classification in simulation. [Work supported by ONR Code 322OA.]
Measurements and modeling of acoustic scattering from targets in littoral environments
Authors: Simpson Harry J. , Waters Zackary J. , Yoder Timothy J. , Houston Brian H. , Jig Kyrie K. , Volk Roger R. , Bucaro Joseph A.
Published: October 2014

Broadband laboratory and at-sea measurements systems have been built by NRL to quantify the acoustic target strength of objects sitting on or in the bottom of littoral environments. Over the past decade, these measurements and the subsequent modeling of the target strength have helped to develop an understanding of how the environment, especially near the bottom interface, impacts the structural acoustic response of a variety of objects. In this talk we will present a set of laboratory, at-sea rail and AUV based back scatter, forward scatter, and propagation measurements with subsequent analysis to understand the impact of the littoral environment. Simple targets such as spheres, along with UXO targets will be discussed. The analysis will be focused on quantifying the changes to target strength as a result of being near the bottom interface. In addition to the traditional backscatter or monosatic target strength, we focus upon efforts to investigate the multi-static scattering from targets. [Work supported by ONR.]
A correlation analysis of the Naval Surface Warfare Center Panama City Division's (NSWC PCD) database of simulated and collected target scattering responses focused on automated target recognition
Authors: Lim Raymond , Malphurs David E. , Prater James L. , Lee Kwang H. , Sammelmann Gary S.
Published: October 2014

Recently, NSWC PCD participated in a number of computational and experimental efforts aimed at assembling a database of sonar scattering responses encompassing a variety of objects including UXO, cylindrical shapes, and other clutter-type objects. The range of data available on these objects consists of a simulated component generated with 3D finite element calculations coupled to a fast Helmholtz-equation-based propagation scheme, a well-controlled experimental component collected in NSWC PCD’s pond facilities, and a component of measurements in realistic underwater environments off Panama City, FL (TREX13 and BayEX14). The goal is to use the database to test schemes for automating reliable separation of these objects into desired classes. Here, we report on an initial correlation analysis of the database projected onto the target aspect vs frequency plane to assess the feasibility of the simulated component against the measured ones, to investigate some basic questions regarding environmental and range effects on class separation, and to try and identify phenomena in this plane useful for classification. [Work supported by ONR and SERDP.]
Identifying buried unexploded ordnance with structural acoustics based numerically trained classifiers: Laboratory demonstrations
Authors: Waters Zachary J. , Simpson Harry J. , Houston Brian H. , Jig Kyrie , Volk Roger , Yoder Timothy J. , Bucaro Joseph A.
Published: October 2014

Strategies for the automated detection and classification of underwater unexploded ordnance (UXO), based upon structural acoustics derived features, are currently being transitioned to autonomous underwater vehicle based sonar systems. The foundation for this transition arose, in part, from extensive laboratory investigations conducted at the Naval Research Laboratory. We discuss the evolution of structural acoustic based methodologies, including research into understanding the free-field scattering response of UXO and the coupling of these objects, under varying stages of burial, to water-saturated sediments. In addition to providing a physics-based understanding of the mechanisms contributing to the scattering response of objects positioned near the sediment–water interface, this research supports the validation of three-dimensional finite-element-based models for large-scale structural–acoustics problems. These efforts have recently culminated with the successful classification of a variety of buried UXO targets using a numerically trained relevance vector machine (RVM) classifier and the discrimination of these targets, under various burial orientations, from several objects representing both natural and manmade clutter. We conclude that this demonstration supports the transition of structural acoustic processing methodologies to maritime sonar systems for the classification of challenging UXO targets. [Work supported by ONR and SERDP.]
Wideband imaging with the decomposition of time reversal operator
Authors: Li Chunxiao , Guo Mingfei , Lu Huancai
Published: October 2014

It has been shown that the decomposition of the time reversal operator (DORT) is effective to achieve detection and selectively focusing on pointlike scatterers. Moreover, the multiplicity of the invariant of the time reversal operator for a single extended (non-pointlike) scatterer has been also revealed. In this paper, we investigate the characterization and imaging of the scatterers when an extended scatterer and a pointlike scatterer are simultaneously present. The relationship between the quality of focusing and frequency is investigated by backpropagation of singular vectors using a model of the waveguide in each frequency bin. When the extended scatterer is present, it is shown that the second singular vector can also focus on the target. However, the task of focusing can only be achieved in frequency bins with relatively large singular values. When both scatterers are simultaneously present, the singular vectors are a linear combination of the transfer vector from each scatterer. The first singular vector can achieve focusing on the extended scatterer in frequency bins with relatively large singular values. The second singular vector can approximately focus on the pointlike scatterer in frequency bins that its scattering coefficients are relatively high and the first scattering coefficient of the extended scatterer are relatively low.
Excessive reverberance in an outdoor amphitheater
Authors: Hoover K. Anthony
Published: October 2014

The historic Ford Theatre in Hollywood, CA, is undergoing an overall renovation and expansion. Its centerpiece is the inexplicably asymmetrical 1200 seat outdoor amphitheater, built of concrete in 1931 after the original 1920 wood structure was destroyed by a brush fire in 1929, and well before the adjacent Hollywood Freeway was nearly as noisy as now. Renovation includes reorienting seating for better symmetry while maintaining the historic concrete, and improving audio, lighting, and support spaces. Sited within an arroyo overlooking a busy highway, and in view of the Hollywood Bowl, the new design features an expanded “sound wall” that will help to mitigate highway noise while providing optimal lighting and control positions. New sound-absorptive treatments will address the Ford’s excessive reverberation, currently more than might be anticipated for an entirely outdoor space. The remarkably uniform distribution of ambient noise and apparent contributions by the arroyo to the reverberation will be discussed, along with assorted design challenges.
A decade later: What we’ve learned from The Pritzker Pavilion at Millennium Park
Authors: Laney Jonathan , Miller Greg , Pfeiffer Scott , Giegold Carl
Published: October 2014

Each design and construction process yields a building and systems that respond to a particular client at a particular time. We launch these projects into the wild and all too frequently know little of their daily lives and annual cycles after that. Occasionally, though, we have the opportunity to stay close enough to watch a project wear in, weather (sometimes literally), and respond to changing client and patron dynamics over time. Such is the case with the reinforcement and enhancement systems at the Pritzker Pavilion in Chicago’s Millennium Park. On a fine-grained scale, each outdoor loudspeaker is individually inspected for its condition at the end of each season. Signal-processing and amplification equipment is evaluated as well, so the overall system is maintained at a high degree of readiness and reliability. Strengths and weaknesses of these components thereby reveal themselves over time. We will discuss these technical aspects as well as changing audience behaviors, modifications made for special events, and the ways all of these factors inform the future of audio (and video) in the Park.
An electro-acoustic conundrum—Improving the listening experience at the Park Avenue Armory
Authors: Barbar Steve , Scarbrough Paul
Published: October 2014

Larger than a hanger for a commercial airliner, the Park Avenue Armory occupies an entire city block in midtown Manhattan. Its massive internal volume generates reverberation time in excess of three seconds. However, it functions as a true multi-purpose venue with programming that includes dramatic performances produced by the Manchester International Festival, and musical performances sponsored by Lincoln Center. We will discuss the unique nature of the venue as well as the tools and techniques employed in staging different productions.
Comparison of source stimulus input method on measured speech transmission index values of sound reinforcement systems
Authors: Shade Neil T.
Published: October 2014

One purpose of a sound reinforcement system is to increase the talker’s speech intelligibility. A common metric for speech intelligibility evaluation is the Speech Transmission Index (STI) defined by IEC-60268-16 Revision 4. The STI of a sound reinforcement system can be measured by inputting a stimulus signal into the sound system, which is modified by the system electronics, and radiated by the sound system loudspeakers to the audience seats. The stimulus signal can be input via a line level connection to the sound system or by playing the stimulus signal through a small loudspeaker that is picked-up by a sound system microphone. This latter approach factors the entire sound system signal chain from microphone input to loudspeaker output. STI measurements were performed on two sound systems, one in a reverberant room and the other in relatively non-reverberant room. Measurement results compare both signal input techniques using omnidirectional and hypercardioid sound system microphones and three loudspeakers claimed to be designed to have directivity characteristics similar to the human voice.
Sound levels and the risk of hearing damage at a large music college
Authors: Plsek Thomas J.
Published: October 2014

For a recent sabbatical from Berklee College of Music, my project was to study hearing loss especially among student and faculty musicians and to measure sound levels in various performance situation ranging from rehearsals to classes/labs to actual public performances. The National Institute for Occupational Safety and Health (NIOSH) recommendations (85 dBA criterion with a 3 dB exchange rate) were used to determine the daily noise dose obtained in each of the situations. In about half of the situations 100% or more of the daily noise was reached. More measuring of actual levels reached is needed as are noise dosimetry measurements over an active 12–16 hour day.
Shelf-scale mapping of fish sound production with ocean gliders
Authors: Mann David , Wall Carrie , Lembke Chad , Lindemuth Michael , He Ruoying , Taylor Chris , Kellison Todd
Published: October 2014

Ocean gliders are a powerful platform for collecting large-scale data on the distribution of sound-producing animals while also collecting environmental data that may influence their distribution. Since 2009, we have performed extensive mapping on the West Florida Shelf with ocean gliders equipped with passive acoustic recorders. These missions have revealed the distribution of red grouper as well as identified several unknown sounds likely produced by fishes. In March 2014, we ran a mission along the shelf edge from Cape Canaveral, FL to North Carolina to map fish sound production. The Gulf Stream and its strong currents necessitated a team effort with ocean modeling to guide the glider successfully to two marine protected areas. This mission also revealed large distributions of unknown sounds, especially on the shallower portions of the shelf. Gliders provide valuable spatial coverage, but because they are moving and most fish have strong diurnal sound production patterns, data analysis on presence and absence must be made carefully. In many of these cases, it is best to use a combination of platforms, including fixed recorders and ocean profilers to measure temporal patterns of sound production.
The use of passively drifting acoustic recorders for bioacoustic sensing
Authors: Barlow Jay , Griffiths Emily , Rankin Shannon
Published: October 2014

Passively drifting recording systems offer several advantages over autonomous underwater or surface vessels for mobile bioacoustic sensing in the sea. Because they lack of any propulsion, self noise is minimized. Also, vertical hydrophone arrays are easy to implement, which is useful in estimating the distance to specific sound sources. We have developed an inexpensive (<$5000) Drifting Acoustic Spar Buoy Recorder (DASBR) that features up to 1 TB of stereo recording capacity and a bandwidth of 10 Hz–96 kHz. Given their low cost, many more recorders can be deployed to achieve greater coverage. The audio and GPS recording system floats at the surface, and the two hydrophones (at 100 m) are de-coupled from wave action by a dampner disk and an elastic cord. During a test deployment in the Catalina Basin (Nov 2013) we collected approximately 1200 hours of recordings using 5 DASBRs recording at 192 kHz sampling rate. Each recorder was recovered (using GPS and VHF locators) and re-deployed 3–4 times. Dolphin whistles and echo-location clicks were detectable approximately half of the total recording time. Cuvier’s beaked whales were also detected on three occasions. Cetacean density estimation and ocean noise measurements are just two of many potential uses for free-drifting recorders.
A commercially available sound acquisition and processing board for autonomous passive acoustic monitoring platforms
Authors: Matsumoto Haru , Klinck Holger , Mellinger David K. , Jones Chris
Published: October 2014

The U.S. Navy is required to monitor marine mammal populations in U.S. waters to comply with regulations issued by federal agencies. Oregon State University and Embedded Ocean Systems (EOS) co-developed a passive acoustic data acquisition and processing board called Wideband Intelligent Signal Processor and Recorder (WISPR). This low-power, small-footprint system is suitable for autonomous platforms with limited battery and space capacity, including underwater gliders and profiler floats. It includes a high-performance digital signal processor (DSP) running the uClinux operating system, providing extensive flexibility for users to configure or re-program the system’s operation. With multiple WISPR-equipped mobile platforms strategically deployed in an area of interest, operators on land or at sea can now receive information in near-real time about the presence of protected species in the survey area. In April 2014, WISPR became commercially available via EOS. We are implementing WISPR in the Seaglider and will conduct a first evaluation test off the coast of Oregon in September. System performance, including system noise interference, flow noise, power consumption, and file compression rates in the data-logging system, will be discussed. [Funding from the US Navy’s Living Marine Resources Program.]
Glider-based passive acoustic marine mammal detection
Authors: Hildebrand John , D'Spain Gerald L. , Wiggins Sean M.
Published: October 2014

Passive acoustic detection of delphinid sounds using the Wave Glider (WG) autonomous near-surface vehicle was compared with a fixed bottom-mounted autonomous broadband system, the High-frequency Acoustic Recording Package (HARP). A group of whistling and clicking delphinids was tracked using an array of bottom-mounted HARPs, providing ground-truth for detections from the WG. Whistles in the 5–20 kHz band were readily detected by the bottom HARPs as the delphinids approached, but the WG revealed only a brief period with intense detections as the animals approached within ~500 m. Refraction due to acoustic propagation in the thermocline provides an explanation for why the WG may only detect whistling delphinids at close range relative to the long-range detection capabilities of the bottom-mounted HARPs. This work demonstrated that sound speed structure plays an important role in determining detection range for high-frequency-calling marine mammals by autonomous gliders and bottom-mounted sensors.
Prototype of a linear array on an autonomous surface vehicle for the register of dolphin displacement patterns within a shallow bay
Authors: Romero-Vivas Eduardo , Von Borstel-Luna Fernando D. , Bustamante Omar A. , Beristain Sergio , Porta-Gándara Miguel A. , Villa Médina Franciso , Gutiérrez-Jagüey Joaquín
Published: October 2014

A semi-resident population of tursiops has been reported in the south of La Paz bay in Baja California Sur, Mexico, where specific zones for social, feeding and resting behaviors have been detected. Nevertheless, increasing human activities and new constructions are attributed to have shifted the areas of their main activity. Therefore, it becomes important to study displacement patterns of dolphins within the bay and their spatial relationship to maritime traffic and other sources of anthropogenic noise. A prototype of an Autonomous Surface Vehicle (ASV) designed for shallow water bathymetry has been adapted to carry a linear array of hydrophones previously reported for the localization of dolphins from their whistles. Conventional beam-forming algorithms and electrical steering are used to find Direction of Arrival (DOA) of the sound sources. The left-right ambiguity typical of a linear array and front-back lobes for sound sources located at end-fire can be resolved by the trajectory of the ASV. Geo-referenced positions and bearing of the array, provided by the Inertial Measurement Unit of the ASV, along with DOA for various positions allows triangulating and mapping the sound sources. Results from both, controlled experiments using geo-referenced know sources, and field trials within the bay, are presented.
Estimating waveguide parameters using horizontal and vertical arrays in the vicinity of horizontal Lloyd’s mirror in shallow water
Authors: Badiey Mohsen
Published: October 2014

When shallow water internal waves approach a source-receiver track, the interference between the direct and horizontally refracted acoustic paths from a broadband acoustic source was previously shown to form Horizontal Lloyd’s mirror (Badiey et al. J. Acoust. Soc. Am. 128(4), EL141–EL147, 2011). While the modal interference structure in the vertical plane may reveal arrival time for the out of plane refracted acoustic wave front, analysis of moving interference pattern along the horizontal array allows measurement of the angle of horizontal refraction and the speed of the nonlinear internal wave (NIW) in the horizontal plane. In this paper we present a full account of the movement of NIW towards a source-receive track and how we can use the received acoustic signal on an L-shaped array to estimate basic parameters of the waveguide and obtain related temporal and spatial coherence functions particularly in the vicinity of the formation of the horizontal Lloyd mirror. Numerical results using Vertical Modes and Horizontal Rays as well as 3D PE calculations are carried out to explain the experimental observations. [Work supported by ONR 322OA.]
A hybrid approach for estimating range-dependent properties of shallow water environments
Authors: Taroudakis Michael , Smaragdakis Costas
Published: October 2014

H hybrid approach based on statistical signal characterization and a linear inversion scheme for the estimation of range dependent sound speed profiles of compact support in shallow water is presented. The approach is appropriate for ocean acoustic tomography when there is a single receiver available, as the first stage of the method is based on the statistical characterization of a single reception using wavelet transform to associate the signal with a set of parameters describing the statistical features of its wavelet sub-band coefficients. A non-linear optimization algorithm is then applied to associate these features with range-dependent sound speed profile in the water column. This inversion method is restricted to cases where the range dependency is of compact support. At the second stage a linear inversion scheme based on modal arrivals identification and a first order perturbation formula to associate sound speed differences with modal travel time perturbations is applied to fine tune the results obtained by the optimization scheme. A second restriction of this stage is that mode identification is necessary. If this assumption is fulfilled the whole scheme may be applied in ocean acoustic tomography for the retrieval of three-dimensional features, combining inversion results at various slices.
Sensitivity analysis of the image source method to out-of-plane effects
Authors: Pinson Samuel , Holland Charles W.
Published: October 2014

In the context of seafloor characterization, the image source method is a technique to estimate the sediment sound-speed profile from broadband seafloor reflection data. Recently the method has been extended to treat non-parallel layering of the sediment stack. In using the method with measured data, the estimated sound-speed profiles are observed to exhibit fluctuations. These fluctuations may be partially due to violation of several assumptions: (1) the layer interfaces are smooth with respect to the wavelength and (2) out-of-plane effects are negligible. In order to better understand the impact these effects, the sensitivity of the image source method to roughness and out-of-plane effects are examined.
Quantitative ultrasound translates to human conditions
Authors: O'Brien William
Published: October 2014

Two QUS studies will be discussed that demonstrate significant potential for translation to human conditions. One of the studies deals with the early detection of spontaneous preterm birth (SPTB). In a cohort of 68 adult African American women, each agreed to undergo up to five transvaginal ultrasound examinations for cervical ultrasonic attenuation (at 5 MHz) and cervical length between 20 and 36 weeks gestation (GA). At 21 weeks GA, the women who delivered preterm had a lower mean attenuation (1.02±0.16 dB/cm MHz) than the women delivering at term (1.39±0.095 dB/cm MHz), p = 0.041. Cervical length at 21 weeks was not significantly different between groups. Attenuation risk of SPTB (1.2 dB/cm MHz threshold at 21 weeks): specificity = 83.3%, sensitivity = 65.4%. The other QUS study deals with the early detection of nonalcoholic fatty liver disease (NAFLD). Liver attenuation (ATN) and backscattered coefficients (BSC) were assessed at 3 MHz and compared to the liver MR-derived fat fraction (FF) in a cohort of 106 adult subjects. At a 5% FF (for NAFLD, FF ≥ 5%), an ATN threshold of 0.78 dB/cm MHz provided a sensitivity of 89%, and specificity of 84%, whereas a BSC threshold of 0.0028/cm-sr provided a sensitivity of 92% and specificity of 96%.
Quantitative ultrasound assessment of tumor responses to chemotherapy using a time-integrated multi-parameter approach
Authors: Tadayyon Hadi , Sadeghi-Naini Ali , Sannachi Lakshmanan , Czarnota Gregory
Published: October 2014

Radiofrequency ultrasound data were collected from 60 breast cancer patients prior to treatment and at during the onset of their several-month treatment, using a clinical ultrasound scanner operating a ~7 MHz linear array probe. ACE, SAS, spectral, and BSC parameters were computed from 2 × 2 mm RF segments within the tumor region of interest (ROI) and averaged over all segments to obtain a mean value for the ROI. The results were separated into two groups—responders and non-responders—based on the ultimate clinical/pathologic response based on residual tumor size and tumor cellularity. Using a single parameter approach, the best prediction of response was achieved using the ACE parameter (76% accuracy at week 1). In general, more favorable classifications were achieved using spectral parameter combinations (82% accuracy at week 8), compared to BSC parameter combinations (73% accuracy). Using the multi-parameter approach, the best prediction was achieved using the set [MBF, SS, SAS, ACE] and by combining week 1 QUS data with week 4 QUS data to predict the response at week 4, providing accuracy as high as 91%. The proposed QUS method may potentially provide early response information and guide cancer therapies on an individual patient basis.
Quantitative ultrasound methods for uterine-cervical assessment
Authors: Hall Timothy J. , Feltovich Helen , Carlson Lindsey C. , Guerrero Quinton , Rosado-Mendez Ivan M. , Huang Bin
Published: October 2014

The cervix is a remarkable organ. One of its tasks is to remain firm and “closed” (5 mm diameter cervical canal) prior to pregnancy. Shortly after conception the cervix begins to soften through collagen remodeling and increased hydration. As the fetus reaches full-term there is a profound breakdown in the collagen structure. At the end of this process, the cervix is as soft as warm butter and the cervical canal has dilated to about 100 mm diameter. Errors in timing of this process are a cause for preterm birth, which has a cascade of life-threatening consequences. Quantitative ultrasound is well-suited to monitoring these changes. We have demonstrated the ability to accurately assess the elastic properties and acoustic scattering properties (anisotropy in backscatter and attenuation) of the cervix in non-pregnant hysterectomy specimens and in third trimester pregnancy. We’ve shown that acoustic and mechanical properties vary along the length of the cervix. When anisotropy and spatially variability are accounted for, there are clear differences in parameter values with subtle differences in softening. We are corroborating acoustic observations with nonlinear optical microscopy imaging for a reality check on underlying tissue structure. This presentation will provide an overview of this effort.
Characterization of anisotropic media with shear waves
Authors: Urban Matthew W. , Aristizabal Sara , Qiang Bo , Amador Carolina , Brigham John C. , Kinnick Randall R. , Zhang Xiaoming , Greenleaf James F.
Published: October 2014

In conventional shear wave elastography materials are assumed to be linear, elastic, homogeneous, and isotropic. These assumptions are important to account for in certain tissues because they are not always appropriate. Many tissues such as skeletal muscle, the kidney, and the myocardium are anisotropic. Shear waves can be used to investigate the directionally dependent mechanical properties of anisotropic media. To study these tissues in a systematic way and to account for the effects of the anisotropic architecture, laboratory-based phantoms are desirable. We will report on several phantom-based approaches for studying shear wave anisotropy, assuming that these materials are transversely isotropic. Phantoms with embedded fibers were used to mimic anisotropic tissues. Homogeneous phantoms were compressed to induce transverse isotropy according to the acoustoelastic phenomenon, which is related to nonlinear behavior of the materials. The fractional anisotropy of these phantoms was quantified to compare with measurements made in soft tissues. In addition, soft tissues are also viscoelastic, and we have developed a method to model viscoelastic transversely isotropic materials with the finite element method (FEM). The viscoelastic property estimation from phantom experiments and FEM simulations will also be discussed.
Multiband center-frequency estimation for robust speckle tracking applications
Authors: Ebbini Emad S. , Liu Dalong
Published: October 2014

Speckle tracking is widely used for the detection and estimation of minute tissue motion and deformation with applications in elastography, shear-wave imaging, thermography, etc. The center frequency of the echo data within the tracking window is an important parameter in the estimation of the tissue displacement. Local variations in this quantity due to echo mixtures (specular and speckle components) may produce a bias in the estimation of tissue displacement using correlation-based speckle tracking methods. We present a new algorithm for estimation and tacking of the center frequency variation in pulse-echo ultrasound as a quantitative tissue property and for robust speckle tracking applications. The algorithm employs multiband analysis in the determination of echo mixtures as a preprocessing step before the estimation of the center frequency map. This estimate, in turn, is used to improve the robustness of the displacement map produced by the correlation-based speckle tracking. The performance of the algorithm is demonstrated in two speckle tracking applications of interest in medical ultrasound: (1) ultrasound thermography and (2) vascular wall imaging.
Echo decorrelation imaging for quantification of tissue structural changes during ultrasound ablation
Authors: Mast T. Douglas , Fosnight Tyler R. , Hooi Fong Ming , Keil Ryan D. , Subramanian Swetha , Nagle Anna S. , Rao Marepalli B. , Wang Yang , Ren Xiaoping , Ahmad Syed A. , Barthe Peter G.
Published: October 2014

Echo decorrelation imaging is a pulse-echo method that maps millisecond-scale changes in backscattered ultrasound signals, potentially providing real-time feedback during thermal ablation treatments. Decorrelation between echo signals from sequential image frames is spatially mapped and temporally averaged, resulting in images of cumulative, heat-induced tissue changes. Theoretical analysis indicates that the mapped echo decorrelation parameter is equivalent to a spatial decoherence spectrum of the tissue reflectivity, and also provides a method to compensate decorrelation artifacts caused by tissue motion and electronic noise. Results are presented from experiments employing 64-element linear arrays that perform bulk thermal ablation, focal ablation, and pulse-echo imaging using the same piezoelectric elements, ensuring co-registration of ablation and image planes. Decorrelation maps are shown to correlate with ablated tissue histology, including vital staining to map heat-induced cell death, for both ex vivo ablation of bovine liver tissue and in vivo ablation of rabbit liver with VX2 carcinoma. Receiver operating characteristic curve analysis shows that echo decorrelation predicts local ablation with greater success than integrated backscatter imaging. Using artifact-compensated echo decorrelation maps, heating-induced decoherence of tissue scattering media is assessed for ex vivo and in vivo ultrasound ablation by unfocused and focused beams.
Quantitative ultrasound imaging to monitor in vivo high-intensity ultrasound treatment
Authors: Ghoshal Goutam , Kemmerer Jeremy P. , Karunakaran Chandra , Abuhabshah Rami , Miller Rita J. , Oelze Michael L.
Published: October 2014

The success of any minimally invasive treatment procedure can be enhanced significantly if combined with a robust noninvasive quantitative imaging modality. Quantitative ultrasound (QUS) imaging has been widely investigated for monitoring various treatment responses such as chemotherapy and thermal therapy. Previously we have shown the feasibility of using spectral based quantitative ultrasound parameters to monitor high-intensity focused ultrasound (HIFU) treatment of in situ tumors [Ultrasonic Imaging, 2014]. In the present study we examined the use the various QUS parameters to monitor HIFU treatment of an in vivo mouse mammary adenocarcinoma model. Spectral parameters in terms of the backscatter coefficient, integrated backscattered energy, attenuation coefficient, and effective scatterer size and concentration were estimated from radiofrequency signals during the treatment. The characteristic of each parameter was compared to the temperature profile recorded by needle thermocouple inserted into the tumor a few millimeters away from the focal zone of the intersecting HIFU and the imaging transducer beams. The changes in the QUS parameters during the HIFU treatment followed similar trends observed in the temperature readings recorded from the thermocouple. These results suggest that QUS techniques have the potential to be used for non-invasive monitoring of HIFU exposure.
Prediction of pressure distribution between the vocal folds using Bernoulli’s equation
Authors: Maddox Alexandra , Oren Liran , Khosla Sid , Gutmark Ephraim
Published: October 2014

Determining the mechanisms of self-sustained oscillation of the vocal folds requires characterization of intraglottal aerodynamics. Since most of the intraglottal aerodynamics forces cannot be measured experimentally, most of the current understanding of vocal fold vibration mechanism is derived from analytical and computational models. Several of such studies have used the Bernoulli’s equation in order to calculate the pressure distribution between the vibrating folds. In the current study, intraglottal pressure measurements are taken in a hemilarynx model and are compared with pressure values that are computed form the Bernoulli’s equation. The hemilarynx model was made by removing one fold and having the remaining fold vibrating against a metal plate. The plate was equipped with two pressure ports located near the superior and inferior aspects of the fold. The results show that pressure calculated using Bernoulli’s equation matched well with the measured pressure waveform during the glottal opening phase and dissociated during the closing phase.
Analysis and virtual modification of the acoustics in the Nebraska Wesleyan University campus theatre auditorium
Authors: Brill Laura C. , Blevins Matthew G. , Wang Lily M.
Published: October 2014

NWU’s McDonald Theatre Auditorium is used for both musical and non-musical performances. The acoustics of the space were analyzed in order to determine whether the space could be modified to better fit its uses. The acoustic characteristics of the room were obtained from impulse responses using the methods established in ISO 3382-1 for measuring the acoustic parameters of a performance space. A total of 22 source/receiver pairs were used. The results indicate a need for increased reverberation in the mid to high frequency ranges of 500–8000 Hz. The experimental results were used to calibrate a virtual model of the space in ODEON acoustics software. Materials in the model were then successfully modified to increase reverberation time and eliminate unwanted flutter echoes to optimize the acoustics to better suit the intended purposes of the space.
The diffraction pattern associated with the transverse cusp caustic
Authors: Frederickson Carl , Frederickson Nicholas L.
Published: October 2014

New software has been developed to evaluate the Pearcey function P±(w1,w2)=∫(-∞)∞ exp[±i(s4/4 + w2s2/2 + w1s)]ds. This describes the diffraction pattern of a transverse cusp caustic. Run-time comparisons between different coding environments will be presented. The caustic surface produced by the reflection of a spherical wavefront from the surface given by h(x,y) = h1x2 + h2xy2 + h3y2 will also be displayed.
Architectural acoustical oddities
Authors: Woodstock Zev C. , Lubert Caroline P.
Published: October 2014

The quad at James Madison University (Virginia, USA) exhibits an uncommon, but not unique, acoustical oddity called Repetition Pitch. When someone stands at certain places on the quad and makes a punctuated white noise (claps, for example) a most unusual squeak is returned. This phenomenon only occurs at these specific places. A similar effect has been observed in other locations, mostly notably Ursinus College (Pennsylvania, USA) and the pyramid at Chichen Itza (Mexico). This talk will discuss Repetition Pitch, as well as other interesting architectural acoustic phenomenon including the noisy animals in the caves at Arcy-sur-Cure (France), the early warning system at Golkonda Fort (Southern India) and the singing angels at Wells Cathedral in the United Kingdom.
Impedance tube measurements of printed porous materials
Authors: Frederickson Carl , McDougal Forrest
Published: October 2014

An impedance tube has been used to make measurements of the acoustic impedance of porous samples. Porous with designed porosities and tortuosities have been produced using 3D printing. Measured impedances are compared to calculated values.
Determining elastic moduli of concrete using resonance
Authors: Munyazikwiye Gerard , Slaton William
Published: October 2014

The elastic moduli of rods of material can be determined by resonance techniques. The torsional, longitudinal, and transverse resonance modes for a rod of known mass and length can be measured experimentally. These resonance frequencies are related to the elastic properties of the material, hence, by measuring these quantities the strength of the material can be determined. Preliminary tests as proof of principle are conducted with metallic rods. Data and experimental techniques for determining the elastic moduli for concrete using this procedure will be presented.
Articulation of sibilant fricatives in Colombian Spanish
Authors: Abell Alexandra , Lulich Steven M.
Published: October 2014

Colombians constitute the largest South American population in the United States at 909,000 (or 24% of the total South American population in the U.S.), and Bogotá, Colombia is the most populated area within the Andean Highland region, yet relatively little is known about Colombian Spanish speech production. The majority of previous studies of Colombian phonetics have relied on perception and acoustic analysis. The present study contributes to Colombian Spanish phonetics by investigating the articulation of sibilant fricatives. In particular, the shape of the palate and tongue during the production of sibilants is investigated in an attempt to quantify the shape and size of the oral cavity in the vicinity of the sibilant constriction. Real-time three-dimensional ultrasound, palate impressions, acoustic recordings, and electroglottography are brought to bear on these issues.
Teaching acoustical interaction: An exploration of how teaching architectural acoustics to students spawns project-based learning
Authors: Butko Daniel , Hardage Haven , Oliphant Michelle
Published: October 2014

The language and methods of architecture typically evaluated through small-scale models and drawings can be complemented by full-scale interactive constructs, augmenting learning through participatory, experiential, and sometimes experimental means. Congruent with Constantin Brancusi’s proclamation, “architecture is inhabitable sculpture,” opportunities to build full-scale constructs introduce students to a series of challenges predicated by structure, connections, safety, and a spirit of inquisition to learn from human interaction. To educate and entertain through sensory design, undergraduate students designed and built an interactive intervention allowing visual translation of acoustical impulses. The installation was developed and calibrated upon the lively acoustics and outward campus display of the college’s gallery, employing excessive reverberation and resonance as a method of visually demonstrating sound waves. People physically inhabiting the space were the participants and critics by real-time reaction to personal interaction. The learning process complemented studio-based instruction through hands-on interaction with physical materials and elevated architectural education to a series of interactions with people. This paper documents and celebrates the Interactive Synchronicity project as a teaching tool outside common studio project representation while enticing classmates, faculty, and complete strangers to interact with inhabitable space.
Signal processing for velocity and range measurement using a micromachined ultrasound transducer
Authors: Guri Dominic , White Robert D.
Published: October 2014

Signal processing techniques are under investigation for determination of range and velocity information from MEMS based ultrasound transducers. The ideal technique will be real-time, result in high resolution and accurate measurements, and operate successfully in noise. Doppler velocity measurements were previously demonstrated using a MEMS cMUT array (Shin et al., ASA Fall Meeting 2011, JASA 2013, Sens. Actuators A 2014). The MEMS array has 168 nickel-on-glass capacitive ultrasound transducers on a 1 cm die, and operates at 180 kHz in air. Post processing of the received ultrasound demonstrated the ability to sense velocity using continuous wave (CW) Doppler at a range of up to 1.5 m. The first attempt at real-time processing using a frequency modulated continuous wave (FM/CW) scheme was noise limited by the analog demodulation circuit. Further noise analysis is ongoing to determine whether this scheme may be viable. Other schemes under consideration include cross correlation chirp and single and multi-frequency burst waveforms. Preliminary results from a single frequency burst showed that cross-correlation-based signal processing may achieve acceptable range. The system is targeted at short range small robot navigation tasks. Determination of surface roughness from scattering of the reflected waves may also be possible.
Investigation of a tongue-internal coordinate system for two-dimensional ultrasound
Authors: Pedro Rebecca , Mazzocco Elizabeth , Csapó Tamás G. , Lulich Steven M.
Published: October 2014

In order to compare ultrasound recordings of tongue motion across utterances or across speakers, it is necessary to register the ultrasound images with respect to a common frame of reference. Methods for doing this typically rely either (1) on fixing the position of the ultrasound transducer relative to the skull by means of a helmet or a similar device, or (2) re-aligning the images by various means, such as optical tracking of head and transducer motion. These methods require sophisticated laboratory setups, and are less conducive to fieldwork or other studies in which such methods are impractical. In this study, we investigated the possibility of defining a rough coordinate system for image registration based on anatomical properties of the tongue itself. This coordinate system is anchored to the lower-jaw rather than the skull, but may potentially be transformed into an approximately skull-relative coordinate system by integrating video recordings of jaw motion.
The effect of finite impedance ground reflections on horizontal full-scale rocket motor firings
Authors: Hord Samuel , Neilsen Tracianne B. , Gee Kent L.
Published: October 2014

Ground reflections have a significant impact on the propagation of sound from a horizontal rocket firing. The impedance of the ground relies strongly on effective flow resistivity of the surface and determines the frequencies at which interference nulls occur. For a given location, a softer ground, with lower effective flow resistivity, shifts the location of interference nulls to lower frequencies than expected for a harder ground. The difference in the spectral shapes from two horizontal firings of GEM-60 rocket motors, over snowy ground, clearly shows this effect and has been modeled. Because of the extended nature of high energy launch vehicles, the exhaust plume is modeled as a partially correlated line source, with distribution parameters chosen to match the recorded data sets as best as possible. Different flow resistivity values yield reasonable comparisons to the results of horizontal GEM-60 test firings.