bluuebunny/crossref_metadata_2025 huggingface dataset:
Shear wave attenuation estimates from Scholte wave data
Authors: Potty Gopu R. , Miller James H. , Buckingham Michael J.
Published: May 2015

Scholte waves are valuable tool for estimating the shear properties of the ocean bottom sediments. Previously estimates of the shear wave speed were obtained using interface wave data from a small scale experiment conducted in very shallow water in coastal Rhode Island. The University of Rhode Island’s shear measurement system consisting of vertical axis and three-axis geophones were used to collect data in 3 m of water. Interface waves were excited by dropping a weight from a research vessel. In this study, we use the geophone data to estimate the depth-averaged shear attenuation using spectral amplitude ratios. The estimated sediment properties will be compared with historic core data from the field test location and other published results for similar type of sediments. The correlation of the shear speed and attenuation to sediment properties such as porosity, grain size and bulk density will be discussed. [Work supported by Office of Naval Research.]
Wave propagation in muddy sediments using time domain finite difference approach
Authors: Clark Holly C. , Stephen Ralph A. , Miller James H. , Potty Gopu R.
Published: May 2015

There is a renewed interest in understanding wave propagation in muddy sediments. In this study, we are using the time domain finite difference approach to investigate wave propagation in a muddy environment representative of the New England Mud Patch south of Martha’s Vineyard. The model uses the two-dimensional full-wave time-domain finite-difference code developed at WHOI over the past 35 years. In order to simplify the computation we consider perfectly elastic, isotropic media with uniform step sizes in time and space. The source waveform is a Ricker wavelet with a peak frequency in pressure of 200 Hz. This study considers a 100 m water waveguide (Vp = 1500 m/s) overlying 12 m of mud (Vp = 1530 m/s, Vs = 100 m/s) above a faster bottom (Vp = 1700 m/s, Vs = 500 m/s). The goal of the modeling was to understand the propagation of compressional, shear and interface waves in the presence of a soft muddy layer. [Work supported by ONR Code 3220A.]
Laboratory and field measurements of Rayleigh waves
Authors: Norton Christopher J. , Miller James H. , Potty Gopu R. , Bradshaw Aaron , Baxter Christopher D.
Published: May 2015

There is a need for rapid and nondestructive sensing of near-surface shear properties of the ground and seafloor. Our approach on land is to measure Rayleigh wave dispersion and invert these measurements to extract a shear wave speed profile. A portable surface wave inversion system has been developed that employs an array of six accelerometers to measure Rayleigh waves excited by simple impulsive sources in the laboratory and in the field. To verify the shear wave speed estimated by the Rayleigh waves, a calibrated bender element system was also developed to provide independent measurements of the shear wave speed profile at selected depths. The bender element system was placed in a test tank initially filled with mason sand and the Rayleigh wave inversion system was deployed on the surface of the sand in the tank. The estimated shear wave speeds were then compared to the results of the bender element system as well measurements by a dynamic cone penetrometer and laser vibrometer. The approach allows for the measurement of shear speeds in for various sediment and soil arrangements in the well-controlled laboratory setting as well in the field. [Work supported by Army Research Office and ONR.]
Application of ultrasound transit time spectroscopy to human cancellous bone for derivation of bone volume fraction in-vitro
Authors: Langton Christian M. , Wille Marie-Luise
Published: May 2015

We have previously demonstrated that ultrasound propagation in complex composite media may be described as an array of parallel sonic rays. The transit time of each sonic ray is determined by the proportion of solid (bone) and fluid (marrow) traversed, the received ultrasound signal being a superposition of all sonic rays. An Ultrasound Transit Time Spectrum (UTTS) for a test sample may be obtained via digital deconvolution of input and output ultrasound signals, describing the proportion of sonic rays having a particular transit time, from which the bone volume fraction (BVF) of the sample may be estimated. In a recent in-vitro study, 21 cancellous bone samples, extracted from 5 human femoral heads following total hip replacement, were measured with microCT to derive the true BVF value. Transmission ultrasound signals of 1 MHz were recorded and UTTS-derived BVF calculated. A coefficient of determination (R2) of 82% was achieved between ultrasound and microCT derived BVF values. Current work is clinically implementing UTTS, noting its potential to estimate bone mineral density, and hence, a means to diagnose osteopenia and osteoporosis using WHO T-score criteria.
Multiscale assessment of cortical bone properties with quantitative ultrasound
Authors: Schneider Johannes , Bernard Simon , Minonzio Jean-Gabriel , Varga Peter , Wendlandt Robert , Grimal Quentin , Laugier Pascal , Raum Kay
Published: May 2015

Clinical bone quality assessment still relies strongly on bone mineral density (BMD). It is now well accepted that BMD predicts only around 60% of the individual fracture risk because it depends on geometrical dimensions of the bone and mechanical properties of its cortical shell. The tibia mid-shaft is a clinically relevant site for ultrasound axial transmission (AT) measurements, which allow simultaneous assessment of cortical thickness (Ct.Th) and tissue elasticity. This ex-vivo study investigated 19 representative human tibiae (native samples, mid-shaft, age range: 69–94 yrs) using AT with the aim to develop novel ultrasound biomarkers of cortical bone loss. Ct.ThAT was in good agreement with corresponding data from micro-computed tomography (R2 = 0.90). Resonant ultrasound spectroscopy was used to measure the transverse isotropic elasticity tensor of extracted bone cubes. Strong linear correlation between axial stiffness (c33) and mass density (R2 = 0.86) was found. Mechanical testing based strength was moderately correlated to c33 (R2 = 0.72) and mass density (R2 = 0.65). These findings indicate the potential of cortical elasticity to be an adequate biomarker of bone quality which combined with information about bone geometry (e.g., Ct.Th) could improve clinical fracture risk assessment.
Backscatter difference techniques for bone assessment using an ultrasonic imaging system
Authors: Hoffmeister Brent K. , Smathers Morgan R. , Miller Catherine J. , McPherson Joseph A. , Thurston Cameron R. , Lee Sang-Rok
Published: May 2015

Background: Backscatter difference techniques are being developed to detect changes in bone caused by osteoporosis. Backscatter difference techniques compare the power in one portion of an ultrasonic backscatter signal to the power in a different portion of the same signal. Goal: Evaluate the feasibility of using an ultrasonic imaging system to perform backscatter difference measurements of bone. Procedure: Ultrasonic signals and images were acquired from 24 specimens of bone using an ultrasonic imaging system (Terason) with a 5 MHz linear array transducer. The signals were analyzed to determine the normalized mean backscatter difference (nMBD) between two gated portions of each signal. The images were analyzed to determine the normalized pixel value difference (nPVD) between regions of interest (ROIs) positioned at two different depths. Results: nMBD demonstrated strong linear correlations with bone mineral density that ranged from 0.83 to 0.87. nPVD performed less well, yielding correlations that ranged from 0.42 to 0.81, depending on ROI separation. Conclusions: It is feasible to apply the backscatter difference technique to ultrasonic imaging systems for the purpose of bone assessment. Better results are obtained by analyzing the signals rather than the images.
Quantitative ultrasound imaging reconstruction in peripheral skeletal assessment
Authors: Qin Yi-Xian , Muir Jesse
Published: May 2015

Disuse osteopenia affect mineral density, microstructure and integrity of bone, which lead to increased risk of osteoporosis and fracture during long term space mission. In order to provide a non-ionizing, repeatable method of skeletal imaging, a novel hand-held scanning confocal quantitative ultrasound (QUS) device has been developed. A mobile scanning ultrasound images were collected using ten sheep tibia and eight human volunteers at the wrist, forearm, elbow, and humerus with the arm submerged in water. A custom MATLAB software used a least-error algorithm to adjust adjacent lines and remove unwanted image waver from hand movement. Ultrasound attenuation (ATT) values of 42.4±0.6 dB and 41.5±1.0 dB were found in water and gel coupling, respectively. Scans of the human subject revealed detailed anatomy of the humerus, elbow, forearm, and hand. Repeat measures of the distal radius found an attenuation of 37.2±3.3 dB, with negligible changes cause by wrist rotation of ±10° (36.4 to 37.3 dB) indicating small changes in scan angle would not significantly affect bone quality measurements. The hand-held QUS device allows for rapid skeletal imaging without ionizing radiation. Information gathered from ultrasonic attenuation and velocity can provide detailed information on localized bone fragility as well as identify fractures.
FDTD simulations of ultrasonic wave propagation in the cortical bone with heterogeneity
Authors: Hata Toshiho , Nagatani Yoshiki , Matsukawa Mami
Published: May 2015

The ultrasonic axial transmission (AT) technique is known to assess the cortical bone of femur and tibia. After the first application of the finite difference time domain (FDTD) method [1], the wave propagation in bone has been discussed by both simulation and experimental studies. The wave propagation depends on the wave velocity, bone geometry (curvature, cortical thickness), anisotropy, heterogeneity, etc. In this study, we have investigated the ultrasonic wave propagation in the cortical bone with heterogeneity (stiffness distribution) by FDTD method. Using the stiffness distribution of bovine cortical bone, experimentally measured by Yamato and Nakatsuji [2], [3], wave propagation of one cycle of sinusoidal wave at 0.5~1 MHz was investigated, assuming cuboid samples. The wave velocities inside the bone were higher than those of the bone surfaces. The complex propagating waves were slightly concentrated at the bone surface. The results indicate that the stiffness distribution is also an important factor to understand the wave propagation. [1] E. Bossy et al., J. Acoust. Soc. Am. 115 , 2314 (2004). [2] Y. Yamato et al., Jpn. J. Appl. Phys. 47, 4096 (2008). [3] T. Nakatsuji et al., Jpn. J. Appl. Phys. 50, 07HF18 (2011).
Use of smartphone sound measurement apps for occupational noise assessments
Authors: Kardous Chucri A. , Celestina Metod
Published: May 2015

NIOSH conducted two studies to examine the accuracy of smartphone sound measurement applications (apps). The first study examined 192 sound measurement apps on the Apple (iOS) and Google (Android) platforms. Only 10 iOS apps met our selection criteria for functionality, measurement metrics, and calibration capability. The studies compared the performance of the apps with a reference microphone and with a professional type 1 sound level meter and a type 2 noise dosimeter. The results showed 4 iOS apps with means of differences within ± 2 dB(A) of the reference microphone. The Android-based apps lacked the features and functionalities found in iOS apps and showed a wide variance between the same app measurements on different devices. A follow-up study of the 4 iOS apps using calibrated external microphones (MicW i436 and Dayton Audio iMM-6), showed an even closer agreement with professional meters. Overall, the studies suggest that certain apps may be used for some occupational noise assessments but only if properly calibrated and used within the hardware limits of the mobile devices. NIOSH and EA LAB are collaborating to develop an occupational sound measurement app for iOS devices in an effort to improve awareness of the noise hazards in the workplace.
Direct visualization of shear waves in viscoelastic fluid using microspheres
Authors: Labuda Cecille , Tierney Connor M. , Dayavansha E. G. Sunethra K. , Gladden Joseph R.
Published: May 2015

Wormlike micellar fluids are viscoelastic and can thus support shear waves. Shear waves in 500 mM CTAB-NaSal micellar were visualized by seeding the fluid with microspheres. This method was compared to visualization by observation of birefringence patterns induced by fluid strain in response to shear stresses. Shear speeds measured using both techniques were consistent. Particle displacement was observed to be a sinusoidal function of time and displacement amplitude decreased quadratically with distance from the source. This supports the possibility of using particle amplitude measurements as a measure of attenuation even at low fluid concentration where birefringence visualization techniques fail.
Determination of the phase speed in a bubbly liquid at the single bubble resonance in an impedance tube using a transfer function technique
Authors: Cheyne Stanley A. , Thurman Hugh O. , McDermott Walter C. , Kelley Charles G.
Published: May 2015

The Transfer function method was used to determine the phase speed in a bubbly liquid at the single bubble resonant frequency. The Transfer function technique is widely used to determine the impedance of an absorbing sample. Once the impedance of the sample is found, the phase speed can be determined. White noise was generated and allowed to propagate upward in a vertical, steel, impedance tube. The top was terminated by a bubble cloud generated by pressurized air forced through hypodermic needles. The sound spectrum was measured at two different points in the pure water by carefully moving a single hydrophone. The transfer function was then determined and used to calculate the phase speed in the bubbly liquid.
Simulation of coupled structural-acoustic response with dynamic damage evolution
Authors: Pitt Jonathan S.
Published: May 2015

A novel time-domain method for simulating dynamic damage evolution in a coupled structural-acoustic system is presented. The system is derived via the theory of continuum damage mechanics, and incorporates standard damage evolution models. The overall solution method is staggered, solving for the dynamic damage evolution first with an explicit step, and then using the new values in the coupled computation of the structural-acoustic system. The spatial domain is discretized using a mixed finite element method, and the temporal space is discretized with a higher-order implicit time discretization scheme. Efforts toward fully coupled verification of the solution algorithm are presented, as are validation studies for cases without evolving damage. Applications with evolving damage are presented, and present a first principles study of changes in the structural acoustic response to dynamically evolving damage in the structure. Examples of downstream usage of the evolving structural response are discussed in the concluding remarks.
Augmenting acoustic phonetics with articulatory features for phone recognition
Authors: Sivaraman Ganesh , Mitra Vikramjit , Nam Hosung , Saltzman Elliot , Espy-Wilson Carol
Published: May 2015

In articulatory phonetics, a phoneme’s identity is specified by its articulator-free (manner) and articulator-bound (place) features. Previous studies have shown that acoustic-phonetic features (APs) can be used to segment speech into broad classes determined by the manner of articulation of speech sounds; compared to MFCCs, however, APs perform poorly in determining place of articulation. This study explores the combination of APs with vocal Tract constriction Variables (TVs) to distinguish phonemes according to their place of articulation for stops, fricatives and nasals. TVs were estimated from acoustics using speech inversion systems trained on the XRMB database with pellet trajectories converted into TVs. TIMIT corpus sentences were first segmented into broad classes using a landmark based broad class segmentation algorithm. Each stop, fricative and nasal speech segment was further classified according to its place of articulation: stops were classified as bilabial (/P/, /B/), alveolar (/T/, /D/) or velar (/K/, /G/); fricatives were classified as labiodental (/F/, /V/), alveolar (/TH/, /DH/, /S/, /Z/), palatal (/SH/, /ZH/) or glottal (/HH/); and nasals were classified as bilabial (/M/), alveolar (/N/) or velar (/NG/). Polynomial kernel support vector machines were trained on APs concatenated with vocal tract constriction features. Results showed that combining acoustic and articulatory features leads to reliable recognition of manner and place of articulation, and improves phone recognition.
Dual electromagnetic articulometer observation of head movements coordinated with articulatory gestures for interacting talkers in synchronized speech tasks
Authors: Tiede Mark , Goldenberg Dolly
Published: May 2015

Previous research has demonstrated that speakers readily entrain to one another in synchronized speech tasks (e.g., Cummins 2002, Vatikiotis-Bateson et al. 2014, Natif et al. 2014), but the mixture of auditory and visual cues they use to achieve such alignment remains unclear. In this work, we extend the dual-EMA paradigm of Tiede et al. (2012) to observe the speech and coordinated head movements of speaker pairs interacting face-to-face during synchronized production in three experimental tasks: the “Grandfather” passage, repetition of short rhythmically consistent sentences, and competing alternating word pairs (e.g., “topper-cop” vs. “copper-top"). The first task was read with no eye contact, the second was read and then produced with eye contact, and the third required continuous eye contact. Head movement was characterized using the tracked position of the upper incisor reference sensor. Prosodic prominence was identified using F0 and amplitude contours from the acoustics, and gestural stiffness on articulator trajectories. Preliminary results show that frequency and amplitude of synchronized head movement increased with task eye contact, and that this was coordinated systematically with both acoustic and articulatory prosodic prominence. [Work supported by NIH.]
Benefits of using polar coordinates for working with ultrasound midsagittal tongue contours
Authors: Heyne Matthias , Derrick Donald
Published: May 2015

Calculating SSANOVA average curves of tongue contours is a technique widely used in the field of speech research to facilitate the comparison of articulatory data (Davidson, 2006). Even though this technique is visually easier to understand and offers better statistical tests than using a concentric grid, Mielke (JASA, in press) has recently shown problems arising from generating SSANOVA curves in the Cartesian plane and has instead suggested the use of polar coordinates. Transferring Cartesian coordinates to the polar plane requires choosing an origin for the polar coordinate system and we hereby propose an alternative way of doing so by estimating the ultrasound transducer position through plotting two lines on an ultrasound image. The resulting average curves are very similar to Mielke’s results but facilitate further analysis of data due to being relative to the estimated transducer position. Such possibilities include cutting off individual tokens at the edges to avoid wiggly ends of average contours, rotating (by adding/subtracting to/from the theta coordinate) and shifting data (by changing the x- and y-coordinates of the estimated origin in the Cartesian plane) to improve the (visual) comparability of ultrasound data across subjects. Some of these techniques were used in Heyne and Derrick (SST, 2014).
Robust automatic speech recognition in reverberation: onset enhancement versus binaural source separation
Authors: Park Hyung-Min , Maciejewski Matthew , Kim Chanwoo , Stern Richard M.
Published: May 2015

The precedence effect describes the auditory system’s ability to suppress later-arriving components of sound in a reverberant environment, maintaining the perceived arrival azimuth of a sound in the direction of the actual source, even though the later reverberant components may arrive from other directions. It is also widely believed that precedence-like processing can also improve speech intelligibility for humans and the accuracy of speech recognition systems in reverberant environments. While the mechanisms underlying the precedence effect have traditionally been assumed to be binaural in nature, it is also possible that the suppression of later-arriving components may take place monaurally, and that the suppression of the corresponding components of the spatial image may be a consequence of this more peripheral processing. This paper compares potential contributions of onset enhancement (and consequent steady-state suppression) of the envelopes of subband components of speech at the monaural and binaural levels. Experimental results indicate that substantial improvement in recognition accuracy can be obtained in reverberant environments if feature extraction includes both onset enhancement and binaural interaction. Recognition accuracy appears to be relatively unaffected by which stage in the binaural processing is the site of the suppression mechanism. [Work supported by the LG Yonam Foundation and Cisco.]
A coder with adaptive filters and non-uniform techniques for simple speech communication
Authors: Bae Seonggeon , Kim Myungsook , Bae Myungjin
Published: May 2015

This paper proposes a new method of non-uniform sampling coding that utilizes a modified zero-crossing rate filter and a variable filter. In speech signals, the modified zero-crossing rate refers to the number of times in which the signal crosses zero in a single frame; the rate is high in noisy sections but low in sections of vocal sounds that are quasi-periodic. And the modified zero-crossing rates of unvoiced signals are similar to those of voiced signals. In speech signals, the non-uniform sampling coding method utilizes the peaks and valleys in a frame. In noisy sections, there are a lot of zero crossings and thus creating many peaks and valleys, while sections with voice sounds have zero-crossings numbering only 2–3 times of their fundamental frequency. The method proposed in this paper utilizes the number of peaks and valleys in determining the validity of a sample; the less we have peaks and valleys, the higher compression rates we get. Therefore, by decreasing the number of samples from sections with noise and voiceless sounds which have a high number of peaks and valleys, and by creating a signal that has little effect on the recognized signals, we may acquire a better compression rate. As examined and proposed in this paper, these features can be used to design a filter coefficient for a better performance in order to improve compression rates of non-uniform sampling coding and to maintain high quality signals.
Smiled speech in a context-invariant model of coarticulation
Authors: Akinbo Samuel , Heins Thomas J. , Keough Megan , McClay Elise K. , Ozburn Avery , Schwan Michael D. , Schellenberg Murray , de Vries Jonathan , Gick Bryan
Published: May 2015

Smiling during speech requires concurrent and often conflicting demands on the articulators. Thus, speaking while smiling may be modeled as a type of coarticulation. This study explores whether a context-invariant or a context-sensitive model of coarticulation better accounts for the variation seen in smiled versus neutral speech. While context-sensitive models assume some mechanism for planning of coarticulatory interactions [see Munhall et al., 2000, Lab Phon. V, 9–28], the simplest context-invariant models treat coarticulation as superposition [e.g., Joos, 1948, Language 24, 5–136]. In such a model, the intrinsic biomechanics of the body have been argued to account for many of the complex kinematic interactions associated with coarticulation [Gick et al., 2013, POMA 19, 060207]. Largely following the methods described in Fagel [2010, Dev. Multimod. Interf. 5967, 294–303], we examine articulatory variation in smiled versus neutral speech to test whether the local interactions of smiling and speech can be resolved in a context-invariant superposition model. Production results will be modeled using the ArtiSynth simulation platform (www.artisynth.org). Implications for theories of coarticulation will be discussed. [Research funded by NSERC.]
High fidelity analysis of vowel acoustic space
Authors: Coen Michael H. , Vorperian Houri K. , Kent Raymond D.
Published: May 2015

Vowel acoustic space is often characterized by polygons, whose vertices are determined by summary statistics such as mean values of the formant frequencies of distinct phonemes. The F1-F2 quadrilateral is the most familiar of these. However, using summary statistics to represent formant-frequency data presents fundamental limitations. These data are inherently lossy—summarizing large amounts of data with single values; mean itself is a non-robust statistic, highly sensitive to outliers; and even robust statistics ignore distributional information within the data, which can vary markedly among different phonemes and age groups. We introduce a new approach characterizing and measuring change in formant spaces statically and developmentally. This approach treats acoustic spaces as point clouds of data, in which no information is abstracted or lost. Within this framework, we measure the spatial overlap of sets of formant data using an approach combining optimization theory and computational statistics. This provides highly sensitive measures of both similarity and extent of temporal change. This novel approach is robust with respect to outliers, noise, and missing values. It also has a strong intuitive and rigorous mathematical foundation and is easily visualized. Finally, it enables detailed examination of individual phonemes and clustering of speakers identifying shared developmental patterns. [Work was supported by NIH grants # R01-DC 006282 & P30-HD03352.]
My time with Dr. “Dick” Campbell
Authors: Michalson William R.
Published: May 2015

I have been asked by a former student if I would have any interest in speaking about my experiences with Dick Campbell as a colleague and friend during our time working together. My answer? Of course, I would be honored to speak about the unofficial “Mayor of Woods Hole.” We met shortly after I joined WPI. Dick’s interest in acoustics and my interest in music electronics began a working relationship that evolved into a years-long friendship. Our collaborations benefited (and annoyed) the students we co-advised. Dick was bedridden when we last worked together, but that was Dick—have laptop, will Skype. He never seemed to let the “little things” get in the way of anything that grabbed his interest. I will talk about some of the projects we worked on together, including acoustic modeling, identification of mosquito species by their acoustic signature, and others. Additionally, I’ll talk about the times I spent in his office at WPI, the “acoustics lab” in the Higgins garage, and his laboratory in Woods Hole—the World headquarters for “Bang-Campbell.” Thank you for your attention, and thank you Dick. You’ve been an extraordinarily influential person in my life and the lives of many others.
Acoustic radiation force in biomedical applications: origin, past, present, and future
Authors: Sarvazyan Armen
Published: May 2015

In this talk, an overview of history and physical basis of biomedical applications of acoustic radiation force with a further look into new developments in this field will be presented. In 1902, Lord Rayleigh published his classical work on the theory of sound, introducing the concept of acoustic radiation pressure. Experimental demonstration of radiation force acting on particles in the standing wave field was made by August Kundt (1874). Much later, Wood and Loomis built radiation force balance (1927). Detailed analysis of ultrasound radiation force related to biomedical applications was made in numerous reviews and original articles of Wes Nyborg in the 1960s and 1970s. In spite of over century-old history, most of the significant biomedical applications of acoustic radiation force became known and were extensively studied only during last couple of decades. We will present and discuss recent progress in numerous applications such as the elasticity imaging, assessing viscoelastic properties of biological tissue, monitoring lesions during therapy, the manipulation of cells in suspension, acoustical tweezers, targeted drug and gene delivery. In addition to well established applications, the acoustic radiation force has considerable potential in numerous new areas, which will be discussed in the talk. [NIH R21AR065024.]
Acoustic radiation force and particle dynamics in cylindrical resonators
Authors: Ostrovsky Lev A.
Published: May 2015

Acoustic radiation force is widely used in biomedical studies and medical diagnostics. Among the promising areas of its application is concentration and stirring of particles and bubbles in ultrasonic resonators (e.g., [1]). In a number of cases, cylindrical resonators have a practical advantage vs. plane resonators (acoustic interferometers) due to the axial energy concentration [2], [3]. Theoretical analysis of particle dynamics in such resonators is often very complicated. This presentation outlines recent results in modeling of dynamics of micro-particles and microbubbles in cylindrical resonators. In particular, concentration and separation of “heavy” and “light” particles and near-resonant bubbles are discussed. The role of ultrasound nonlinearity in the considered effects is also discussed. [1]. A. Sarvazyan and L. Ostrovsky, J. Acoust. Soc. Am. 125, 3548–3554 (2009). [2]. A. Priev and A. Sarvazyan, J. Acoust. Soc. Am. 125, 2593 (2009). [3]. L. Ostrovsky, A. Priev, V. Ponomarev, and Y. Barenholz, Proc. Meetings Acoust. 14, 020002 (2013).
Acoustic separation of milk fat globules—Principles in large scale processing
Authors: Leong Thomas , Johansson Linda , Juliano Pablo , Manasseh Richard
Published: May 2015

The acoustic manipulation of particulates in standing wave fields is a well-established technique, with the fundamental theory describing the acoustic radiation forces first reported in 1934 by King. To date, there are few demonstrations of the technique on a volume-scale relevant to industrial application, due to difficulties in scaling the acoustic radiation forces over large distances. Other issues such as the onset of acoustic streaming with high acoustic power input may also impact upon the effectiveness of separation in large systems by disrupting the collection of particulates in the pressure nodal/antinodal regions. In recent work, we have demonstrated the capability of ultrasonic standing waves applied in a liter-scale vessel to concentrate and/or remove fat globules from whole milk with volume throughputs up to 30 L/h. By tuning parameters according to acoustic fundamentals, the technique can be used to specifically select milk fat globules of different sizes in the collected fractions. We report key design and operation principles at large scale using milk as a model system, which has potential to be applied to particulate fluids of biomedical relevance such as blood and lipids.
Across-channel processing of interaural level differences
Authors: Goupell Matthew
Published: May 2015

Interaural level differences (ILDs) are produced when sounds occur away from the midline. The attenuation at the ear that is farther from the source location is frequency dependent and sometimes non-monotonic, resulting in inconsistent ILDs across frequency. It is unclear how the binaural system processes inconsistent ILDs. Ten normal-hearing listeners were presented one or three narrowband noises that varied in center frequency. Consistent or inconsistent ILDs were applied to the bands and listeners were asked to perform a left-right discrimination task. Diotic level roving was introduced to diminish listeners’ ability to utilize monaural cues. Results show that thresholds were nearly frequency independent for one noise band. For three bands, thresholds became frequency dependent with the worst performance at 4 kHz, suggesting across-frequency ILD processing is a complex operation. These results have implications for people who do not heavily rely on low-frequency interaural time differences to localize sounds, such as bilateral cochlear-implant users.
Auditory localization performance in the azimuth for tactical communication and protection systems
Authors: Gaston Jeremy R. , Mermagen Timothy , Foots Ashley , Dickerson Kelly
Published: May 2015

An important consideration in assessing auditory abilities is the effect personal protective equipment (PPE) can have on performance. Tactical Communication and Protection (TCAP) systems are a type of PPE that is becoming more common in military applications. These types of systems provide radio communications, while also protecting the user from hazardous noise through passive and active attenuation. These systems have an active acoustic pass-through mechanism that utilizes an external microphone and internal earphone to restore environmental hearing. Past research has shown that this type of pass-through mechanism can negatively affect localization ability. In the present study, six participants localization ability was tested for two different signals (AK-47 impulse, 500 ms white noise) across an array of eight loudspeakers arranged in a ring around the test participant. The systems tested consisted of three types of in-ear TCAPs, one over-the-ear TCAPs, and one passive nonlinear hearing protection device. All systems were tested with the Advanced Combat Helmet (ACH) donned. In general, localization performance was worst for the AK-47 impulse signal. Across signals, the over-the-ear TCAPs had significantly more front/back confusions and greater localization error than the in-ear systems.
@BYUAcoustics: Using social media to enhance research and outreach at BYU
Authors: Harker Blaine M. , Neilsen Tracianne B. , Gee Kent L. , Whiting Jennifer K. , Berardi Mark L. , White Pauline , Ortega Nicholas D. , Calton Matthew F.
Published: May 2015

Social media has become an increasingly common method of attracting the attention of fellow researchers and promoting interest in acoustics worldwide. A concerted effort has been recently made by the Acoustics Research Group at Brigham Young University to promote acoustics with various methods of enhanced communications. Web page articles were developed with lay-language introductions to the group’s research activities, which can be shared directly to social media sites. The group’s Facebook page and research Twitter account @BYUacoustics provide information about current research meetings, publications, and acoustics in the news, which help network with students who may be interested in joining the acoustics program and which keep alumni informed of current events. In addition, our outreach efforts have been augmented by use of social media. A YouTube channel has been created that contains videos of acoustical demonstration from our outreach show. A general audience Twitter account @Sounds2Astound has been utilized to connect with students in our descriptive class and to K-12 teachers who often bring their students to tour our facilities. The overall effectiveness of each system is assessed using webpage statistics, analytics, and perceived success in reaching target audiences. Successes and limitations are summarized and lessons learned are outlined.
Infrasound study of the atmospheric fine-scale wind velocity structure and its variability
Authors: Chunchuzov Igor , Kulichkov Sergey , Perepelkin Vitaly , Popov Oleg , Assink Jelle , Waxler Roger
Published: May 2015

The results of study of the fine-scale wind velocity structure in the upper stratosphere, mesosphere, and lower thermosphere by using recently developed method of infrasound probing of the atmosphere are presented. The method is based on the effect of infrasound scattering from highly anisotropic wind velocity and temperature nonhomogeneities in the middle and upper atmosphere. The vertical profiles of the wind velocity fluctuations in the upper atmosphere (up to a height of 140 km) are retrieved from the wave forms and travel times of the infrasound signals from volcanoes and surface explosions. The vertical wavenumber spectra of the retrieved wind velocity fluctuations are obtained for the upper stratosphere. Despite the difference in the location of explosive sources all the obtained spectra show the existence of high vertical wavenumber spectral tail with certain power law decay. The effect of a fine-scale wind velocity structure and its variability on the wave forms, coherence, and frequency spectra of the infrasound arrivals is studied. The possibility to use retrieved wind velocity structure in the upper stratosphere and lower thermosphere for improving an infrasound monitoring of infrasound sources in the atmosphere and parameterizing statistical characteristics of anisotropic turbulence (variances, spatial and temporal spectra, and coherence) is discussed.
Spall effects on infrasound generation from explosions at the Nevada National Security Site
Authors: Jones Kyle R. , Rodgers Arthur J. , Whitaker Rodney W. , Ezzedine Souheil M. , Vorobiev Oleg Y.
Published: May 2015

We apply two methods to evaluating the spall signature from underground chemical explosions such as those at the Source Physics Experiment (SPE) at the Nevada National Security Site (NNSS). The first approach uses the Rayleigh integral to compute overpressures for buried explosions from synthetic vertical acceleration data at surface ground zero. To obtain the acceleration data, we systematically vary parameters such as the spall duration, depth of burial and magnitude and observe the effect on the resulting acoustic waveform shape. The second method uses a hydrodynamic approach to more fully characterize the varied parameters to produce the acoustic waveforms. As the spall decreases we find that the acoustic waveform shape changes dramatically. This waveform signature may provide diagnostics on the explosive source and may be a useful metric for underground explosion monitoring. [This work was done under award number DE-AC52-06NA25946. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.]
Sound induced plume instability
Authors: Naugolnykh Konstantin A.
Published: May 2015

A sustained source of buoyancy creates a continuous rise of lighter fluid through the ambient denser fluid, with mixing occurring along the way. Such structure, called as a plume, is sensitive with respect to flow perturbations. In particular, the effect of sound can modulate the structure of plume as a result of sound-turbulent interaction. The acoustic wave can slightly change the structure of flow and then interact with in-phase spatially modulated turbulence. In application to plume this effect is considered in the present paper follow the approach of Chimonas, 1972 and Moiseev et al., 2000.
Visual capture of a stereo image
Authors: Zhou Yi , Montagne Christopher
Published: May 2015

This study investigated visual bias in localizing a “phantom” sound source generated by a stereo pair of speakers. The lateral position of the fused auditory image was controlled by varying the time delay or intensity ratio of two 15-ms noise bursts presented from two hidden loudspeakers positioned at + /− 45 degrees in azimuth. Visual stimuli were delivered from three LEDs positioned at −45, 0, and 45 degrees in azimuth. A multiple-alternative, forced choice task was implemented to measure listener’s perceived sound localization with and without LED stimulation. The magnitude of visual capture (bias) was compared for the two stimulus manipulations—time delay and intensity ratio. Eleven normal hearing listeners participated in the task. Results showed stronger visual capture for time delay than intensity ratio manipulation. Binaural signal analyses were further conducted on ear-canal signals recorded from a KEMAR, showing that time delay manipulation introduced ambiguous binaural and spectral cues. The degree of visual bias was found to be correlated with the ambiguity of localization cues in the task.
The interconnection of binaural and stereoscopic cues for distance perception
Authors: Murphy Kristen
Published: May 2015

Encountering objects within our three-dimensional environment is a combination of sensory cues. While much research has been conducted on how the auditory and visual systems singularly locate objects in space, studies in cross-modal interaction of these two systems suggest the overall perception of a stimulus cannot fully be described by a single sensory system. The purpose of this study was to examine the relationship between visual and acoustic cues specifically in understanding depth perception. Previous studies of audio-visual interaction of spatial perception have accounted for many different auditory depth cues, but have not fully cross examined a number of visual depth cues. Participants were asked to determine the egocentric distance of a stimulus in a virtual three dimensional environment in terms of real-size quantitative scale. Stimuli were presented as either audio only, visual only, or audio and visual. The single-modal and multi-modal results were analyzed and compared against the null hypothesis that when presented simultaneously, the visual depth cues dominate the distance judgment and the acoustic depth cues have no bearing. In this study, the null hypothesis was not rejected, in accord with previous research investigating the proximity image effect.
Auditory scene analysis with a multi-modal model
Authors: Walther Thomas
Published: May 2015

By integrating state-of-the-art auditory scene-analysis methods with artificial cognitive feedback, the current project challenges human performance in quality of experience tasks and auditory scene analysis. Human listeners are regarded as multi-modal agents that develop their concept of the world by exploratory interaction. The prominent goal of the project is to develop an intelligent, computational model of active auditory perception and experience in a multi-modal context. The resulting system framework will form a structural link from binaural perception to judgment and action, realized by interleaved signal-driven (bottom-up) and hypothesis-driven (top-down) feedback processing within an innovative expert-system architecture. A conceptual overview of the project framework is presented, and insight is given into the current state of research, focusing on CASA-related search-&-rescue (S&R) scenarios. In these scenarios, an autonomous robot is endowed with auditory/visual feature-analysis facilities that provide it with bottom-up information of its environment. Top-down evaluation of the extracted features then results in cognitive feedback loops that allow the machine to adapt to complex S&R scenarios and perform significantly better than would be possible by only employing feed-forward control mechanisms. [Work performed in the context of the EU project Two!Ears.]
A bi-modal model to simulate auditory expectation for reverberation time and direct-to-reverberant energy from visual feedback
Authors: Braasch Jonas , Pastore M. T. , Deshpande Nikhil , Blauert Jens
Published: May 2015

A bi-modal model is presented that predicts the psychophysical results of Valente and Braasch [Acustica, 2008]. The model simulates expectation of room-acoustical qualities due to visual cues. The visual part of the model estimates angles of incidence and delays of the first two side reflections of a given frontal sound source. To this end, a stereoscopic image is used to determine azimuth angles and distances for the two frontal room corners. The distance estimates are derived by using the angular differences between the left- and right-eye images of each corner. The model then calculates the room volume by reconstructing a rectangular room from these data, assuming a range of possibilities for the missing room coordinates. In a next step, logarithmic fits of volume to expected reverberation time and of volume to direct-to-reverberant energy ratio predict the expected value ranges for these two parameters. Using a feedback structure, the visually-derived acoustic parameters become input to an auditory Precedence-Effect model, where they are used to pre-adjust inhibition parameters for two acoustic side reflections. These inhibition parameters are consequently refined in the course of the analysis of the incoming sound. [Work supported by NSF #1229391/#1320059 and ERC FP7-ICT-2013-C-#618075.]
Vibration exposure characteristics and health risk prevention strategies associated with vibration exposure during mining applications
Authors: Eger Tammy R. , Dickey James P.
Published: May 2015

Occupational exposure to vibration can lead to health problems and is typically classified as whole-body vibration (WBV), hand-arm vibration (HAV), or foot-transmitted vibration (FTV). Vibration exposure characteristics are typically measured and compared to standards (ISO 2631-1; ISO 5349-1; EU Directive 2002/44/EC) in an effort to determine the probability of adverse health effects including: low-back pain, spinal degeneration, and gastrointestinal tract problems linked with exposure to WBV; decreased grip strength, tingling/numbness in the fingers/hands, and blanching of the fingers associated with exposure to HAV; and numbness/tingling in the feet/toes, and cold induced blanching of the toes stemming from exposure to FTV. The presentation will summarize vibration exposure data collected by the research team over a 10-year period which suggests operators of load-haul-dump vehicles, haulage trucks, and dozers are exposed to WBV above recommended guidelines, while operators of jack-legs are exposed to HAV above guidelines. Our data also suggest miners exposed to FTV associated with drilling off of raise platforms and operating bolters and jumbo drills are at risk of developing a vibration-induced injury. The presentation will also review the effectiveness of control strategies evaluated by the research team including seating, isolation platforms, “anti-vibration” drills, cab interventions, road maintenance, and operating speeds.
Phonetic drift in a first language dominant environment
Authors: Herd Wendy , Walden Robin , Knight Whitney , Alexander Savana
Published: May 2015

Phonetic drift, changes in the first language (L1) sound system as a result of acquiring a second language (L2), has been documented in learners immersed in L2-dominant environments. Less attention has been given to phonetic drift in speakers learning an L2 in L1-dominant environments. In this study, we conducted a cross-sectional analysis of English learners of Spanish in the United States at beginning (N = 12), intermediate (N = 12), advanced (N = 9), and near native (N = 6) proficiency levels. Participants were recorded reading a pseudo-randomized list of words including heed, hayed, who’d, hoed to measure drift in vowels and poll, bowl, toll, dole, coal, goal to measure drift in oral stops. Significant differences in vowel quality and in the VOT of voiced stops were found. Intermediate, advanced, and near native learners of Spanish produced vowels in more peripheral positions of the vowel space than beginning learners of Spanish. Similarly, intermediate, advanced, and near native learners produced voiced stops with more negative VOTs than beginning learners. All of these effects were strongest in near native learners. These results suggest that phonetic drift occurs not only when learners are immersed in L2-dominant environments but also as a result of language instruction in L1-dominant environments.