bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of nonlinear parameters applying uniaxial and shear stress to inhomogeneous viscoelastic media
Authors: Krit Timofey
Published: November 2013

Static shear deformations of a plane-parallel layers of several viscoelastic media created simultaneously with the uniaxial compression are considered. Each layer is fixed between two rigid plates. Displacement of one plate relative to the other resulted in shear strain of the layer. This strain could reach 0.6 of the layer thickness. At such strain, effects due to the cubic nonlinearity arise. It is shown that measuring the dependence of the shear stress on the shear strain along one axis at different compression along the perpendicular axis one could determine nonlinear Landau parameters. The measurements were performed in layers of plastisol, gelatin, and farina-gelatin of 7 mm thickness with a rectangular base 8.9 × 8.9 cm, mounted between three aluminum plates. The upper plate was loaded with masses ranging from 0 to 25 kg and was fixed in each series of the stress-strain measurements. The values of the Landau coefficient A were measured in layers with different value of linear shear modulus. The different behavior of stress-strain curves was observed for media with different composition. [Work supported by the Russian Foundation for Basic Research (Grant Nos. 12-02-00114 and 12-02-31418), and grant of the Government of the Russian Federation 11.G34.31.0066.]
High-frequency ultrasound of breast tissue phantoms with histology mimicking microstructures
Authors: Butler Audrey P. , Omer Robyn K. , Doyle Timothy E.
Published: November 2013

The objectives of this study were to develop breast tissue phantoms with microstructures that accurately mimic the histology of normal and malignant tissue, and to determine the effects of these microstructures on high-frequency (HF) ultrasonic spectra (10–100 MHz). Phantoms were created from a mixture of water, gelatin, and soluble fiber. To simulate various breast tissue histologies, polyethylene beads and nylon fibers with a range of diameters were embedded into phantoms. Microstructures ranging from simply dispersed beads to bead-fiber constructs resembling terminal ductal lobular units were modeled and tested. Pitch-catch and pulse-echo measurements were acquired using 50-MHz transducers, a HF pulser-receiver, and a 1-GHz digital oscilloscope. Spectra were derived from the data and peak densities (the number of peaks and valleys in a specified spectral range) were determined from the spectra. Preliminary results from dispersed beads (58–925 µm diameter) of constant volume concentration (0.8%) indicated that the smaller beads produced higher peak densities than the larger beads with a consistent trend. The higher peak densities can be attributed to either the higher number of scatterers for small beads or the size of scatterer in relation to the ultrasonic wavelength. These and results from more advanced histologically accurate microstructures will be discussed.
Characterizing breast cancer cell lines using principal component analysis of high-frequency ultrasonic spectra
Authors: Thompson Laurel A. , Stiles Janeese E. , Marvel Mandy H. , Sugiyama Janice E. , Doyle Timothy E.
Published: November 2013

Current methods for determining the molecular subtypes of breast cancer include DNA microarrays, immunohistochemical staining, and proteomic analysis. These methods are not easily transferable to real-time clinical applications such as the intraoperative assessment of margin or biopsy specimens. The development of a diagnostic method for rapidly determining the molecular subtype of malignant breast tissue in a clinical setting would represent a significant advance in breast cancer detection and treatment. Preliminary results suggest that high-frequency ultrasound may be sensitive to variations between breast cancer cell lines, and thus molecular subtype, due to a mechanism linking subtype mutations to the ultrasonic properties of the cells. This mechanism was explored using an integrated experimental and computational method. Ultrasonic scattering from breast cancer cells in vitro were simulated using a multipole-based approach. Variations between cell lines due to different molecular subtypes were modeled using a range of cell moduli and sizes. Model and experimental spectra were compared using principal component analysis (PCA). The results indicate the properties and thus molecular subtypes of breast cancer cells could potentially be determined by comparing their measured spectra to model spectra using a feature classification program such as PCA. [This work was supported by Utah Valley University.]
Modeling acoustic propagation in a compartment fire
Authors: Abbasi Mustafa Z. , Wilson Preston S. , Ezekoye Ofodike A.
Published: November 2013

Firefighters unable to move and in need of rescue use an audible alarm to signal for help. Rescue teams can then follow this sound to the firefighter. This alarm is governed by NFPA 1982 : Standard on Personal Alert Safety System (PASS). Introduced in 1983, the PASS has saved many firefighter lives. However, a number of incidents have occurred where the PASS is less effective. There have been incidents where the PASS was heard sporadically on the fireground, or where localization of the alarm was difficult, leading to injury and loss of life. We hypothesized that the temperature field created by the fire is distorting the sound, making it difficult to recognize and localize. At ICA 2013, the authors presented experimental results showing changes in the room acoustic transfer function as the fire evolved. This paper will present efforts at modeling these effects. Using a combination of computational fluid dynamics and wave models, a comprehensive model will be presented capable of modeling sound propagation in the firefighting environment. The goal of this work is to develop a PASS signal more robust against distortion by the fire, and better able to serve the firefighting community. [Work supported by DHS/FEMA.]
Underwater acoustic measurements of an ultrasonic barrier for guidance of American Shad in front of hydroelectric installations
Authors: Lafleur Francois
Published: November 2013

This article presents the results of ultrasonic underwater acoustic measurements in a project guide shads during their downstream migration. Biological issues will be explained to allow the context, but the focus will be on the acoustic problems. In the spring, thousands of shad ascend the St. Lawrence River to spawn downstream of the Central Carillon. After spawning, adults return to sea heading toward the dam Rivière-des-Prairies. The configurations of the installed barriers at the Rivière-des-Prairies dam and at the ile Bizard site will be presented. A design of a signal amplifier was performed to optimize the barrier. A series of simulations and acoustic measurements have been conducted for the evaluation of the emission level of the barrier. The measurement strategy must take into account aspects such as high frequency signal (125 kHz) and geolocation measurement to allow achieving a mapping program of the barrier. The paper will describe: The issue biological; The deployment sites; The mechanism of hearing ultrasonic shad; Configuration of the barrier; The measurement system and the analysis of the results; Typical results obtained for mapping acoustic; Future directions in terms of signal measurements of the acoustic barrier.
Damping in turbulent Navier-Stokes finite element model simulations of wind instruments
Authors: Bader Rolf
Published: November 2013

The flute has a very inefficient energy use, where <1% of the blowing energy ends in the produced sound caused by the high impedance of the blowing hole suggesting a heavy damping in the system. Such damping is known from turbulent flows with high Reynolds numbers. In a FEM simulation of the Navier-Stokes equation of the flute, the inflow of blowing velocity into the flue shows unrealistic values. An alternative is the reasoning of Kolmogorov about turbulent flow as a cascade of vortices satisfying the scaling law as a steady-slope in a log-log relation of vortices size and damping. This is incorporated in the Navier-Stokes model as Reynolds-Averaged-Navier-Stokes model. In a FEM simulation of the flute using this model, the inflow of energy into the flute is modeled realistically, pointing to damping as the crucial factor in flute sound production. As a second example, a transient FEM model of a flow-structure coupling of a saxophone mouthpiece also shows strong damping of the inflow into the mouthpiece due to strong turbulence in the mouthpiece. Only because of this strong damping the system coupled to a tube results in stable oscillations and therefore in a stable tone production.
Bowed string simulation combining digital waveguide and finite-difference time-domain frameworks
Authors: Maestre Esteban , Spa Carlos , Smith Julius
Published: November 2013

In light of the promising results obtained by driving a low-complexity digital waveguide (DW) violin model with synthetic bowing gestures, we are currently exploring the possibilities of combining DW and finite-difference time-domain (FDTD) frameworks to construct refined physical models of string quartet instruments. Departing from state-of-the-art bowed string simulation paradigms, we extend previous approaches by combining a finite-width bow-string interaction model and a dynamic friction model based on simulating heat diffusion along the width of the bow. In our model, DW is used for string propagation, while FDTD is used for bow-string interaction and heat diffusion. The bridge termination is realized using an efficient, passive digital filter obtained from admittance measurements. In this talk, we will present and discuss the current status and future directions of our modeling work, including two-dimensional string vibration simulation for horizontal and vertical polarizations.
A Hamiltonian approach to simulation of acoustic systems involving nonlinear interactions
Authors: Chatziioannou Vasileios , van Walstijn Maarten
Published: November 2013

Nonlinear interactions take place in most systems that arise in music acoustics, usually as a result of player-instrument coupling. Several time-stepping methods exist for the numerical simulation of such systems. These methods generally involve the discretization of the Newtonian description of the system. However, it is not always possible to prove the stability of the resulting algorithms, especially when dealing with systems where the underlying force is a non-analytic function of the phase space variables. On the other hand, if the discretization is carried out on the Hamiltonian description of the system, it is possible to prove the stability of the derived numerical schemes. This Hamiltonian approach is applied to a series of test models of single or multiple nonlinear collisions and the energetic properties of the derived schemes are discussed. After establishing that the schemes respect the principle of conservation of energy, a nonlinear single-reed model is formulated and coupled to a digital bore, in order to synthesize clarinet-like sounds.
Determining annoyance thresholds of tones in noise
Authors: Francis Jennifer , Lee Joonhee , Steinbach Adam , Wang Lily M.
Published: November 2013

Mechanical equipment in buildings often produces noise with significant tones that can lead to complaints. Previous research has identified prominence levels of assorted tonal frequencies, but more work is needed to define at what level the tones at various frequencies lead to human annoyance. This project applies two different methods toward defining annoyance thresholds of tones in noise for two tonal frequencies: 125 Hz and 500 Hz. In the first, subjects are asked to perform a task, while exposed to ten minutes of a broadband noise spectrum with a tonal component set a certain level above the noise. They are subsequently asked to rate their annoyance to that noise condition. Five levels of each of the two tones are tested above two different background noise levels, 40 dBA and 55 dBA. In the second methodology, subjects adjust the level of the tone only above each of the two background noise levels until it is considered to be just annoying. Results obtained for the annoyance thresholds of tones in noise from each of these methods are compared.
A new class of personal noise monitoring devices in hearing conservation
Authors: Yonovitz David , Yonovitz Al , Yonovitz Joshua
Published: November 2013

In the United States, hearing loss affects approximately 35 million people. Occupational noise exposure, the most common cause of noise-induced hearing loss (NIHL) is nearly 100% preventable. Estimates of compensation for NIHL are estimated at 20 billion dollars, making NIHL the costliest environmental and medical-legal problem in the United States. Technology may now be utilized to extend federal and state requirements for the preservation of hearing for those who are exposed to levels that may be injurious to hearing. While noise dosimetry has been routinely utilized to measure workplace exposure, the levels of noise exposure no longer should be predicted but actually measured from personal noise monitoring. Very compact devices with long battery life, high memory capacity to store over 3 months of daily exposure data, USB and automatic RF download capability are now available. The personal noise monitor records percentage of noise exposure integrated over a work day, decibel A-weighted levels, peak levels and the frequency spectrum of noise exposure. Signaling indicators to the wearer as well as acknowledgment of high exposure are part of the personal noise monitor. Trials in various work sectors and will be reported.
Optimizing the acoustic performance of turbochargers
Authors: Ledger David , Pruitt Dan , Diemer Paul
Published: November 2013

Turbocharger usage is predicted to increase in passenger vehicles for reasons such as enabling engine downsizing and improving thermodynamic efficiency. In order to achieve customer expectations, the acoustic performance of the turbo needs to be engineered for a wide range of operating load conditions. This requires the turbo supplier to set component targets in CAE and identify undesirable noises early in the development process using test cell acoustic measurements. Noise from a turbocharger can be separated into two main categories: (1) aeroacoustic sources including blade pass, pulsation, surge and broadband flow noise (2) structureborne from vibration sources such as subsynchronous, first order imbalance, and component resonances. One technique for comparing compressor acoustic performance is noise mapping, where the in duct noise data are collected across the full turbo operating range and post processed into 3D plots. Audible noises that can be generated in a centrifugal turbocharger and methods of identifying sources during development are presented in detail.
Eigenray identification for non-planar propagation
Authors: Blom Philp , Waxler Roger
Published: November 2013

Identifying ray paths connecting a source and receiver at specific locations, or eigenrays, is a trivial exercise in the case of planar propagation since only the initial inclination angle and arrival range of the ray must be considered. However, in the case of propagation in three dimensions, the eigenray search becomes a non-trivial two parameter search. An iterative eigenray search method has been developed employing the auxiliary parameters used to solve the transport equation to efficiently obtain eigenrays connecting a source and receiver in three dimensions. An overview of the method will be presented along with applications to propagation in a simple model atmosphere and analysis of data obtained during the Humming Roadrunner experiment in the fall of 2012.
Measuring the coherency of microbaroms at long distances for the inversion of stratospheric winds
Authors: Marcillo Omar , Arrowsmith Stephen
Published: November 2013

We demonstrate the design of an infrasound network and the associated analysis for measuring the coherency of microbaroms at large distances (10s of km) and inverting for stratospheric winds. We have developed a mathematical framework for the inversion of local stratospheric winds using microbaroms, and found constraints on the optimum sensor network topology. Based on these results, we deployed a prototype sensor network over the winter months (January to March, 2013) that comprised three single-sensor stations, one 30-m and two 1-km arrays with separations between 5 and 70 km. The initial analysis shows periods of very high coherency lasting several hours with tropospheric and low stratospheric celerities. Coherency decreases rapidly with distance and azimuth compared to the direction of propagation of microbaroms. We are exploring topography as the cause of low signal coherency at long distances. Following this pilot study, we are designing a denser sensor network further optimized to capture microbaroms and planning for its deployment and the validation of the inversion scheme using a Doppler Rayleigh Lidar system.
Determining infrasound array performance from frequency response estimation
Authors: Fee David , Dawson Kit , Waxler Roger , Szuberla Curt , Gabrielson Thomas
Published: November 2013

The performance of an infrasound array is typically described qualitatively. In this project, we begin determining quantitative metrics that define the performance of an infrasound array based upon changes in array parameter estimation, particularly direction-of-arrival and trace velocity. First, we determine the magnitude and frequency response of an International Monitoring System (IMS) infrasound array using the in-situ calibration technique. Phase differences in the frequency response between the reference and actual array elements are then represented as a shift in time. These times shifts are used to calculate time differences between non-redundant sensor pairs of the array and are then compared to theoretical time differences for incident plane waves. This allows us to estimate the change in direction-of-arrival and trace velocity due to the unique frequency response of an array using a least-squares technique. We present detailed results for IMS arrays IS26, IS53, IS56, and IS57, which provides a good sampling of different sensors and wind-noise reduction systems in the IMS. For IS53 (Fairbanks, AK), the deviation in the azimuth estimation is bounded below 2 degrees at all frequencies of interest (>0.02 Hz). Preliminary results suggest array parameter estimation at other arrays can be significantly affected by changes in frequency response.
Infrasound signal coherence across arrays: Observations from the international monitoring system
Authors: Green David
Published: November 2013

Arrays of microbarometers are designed to exploit the coherence of infrasound signals between sensors in order to detect and characterize the impinging wavefield. However, signal coherence decreases with increasing distance between measurement locations due to effects that include, but are not limited to, signal multi-pathing, dispersion, and wavefront distortion. Therefore, the design of an array is a balance between ensuring the sensor separations are small enough to guarantee acceptable signal coherence, yet large enough to provide the required resolution when estimating signal azimuth and velocity. Here, we report coherence measurements from more than 30 events that have been recorded on the International Monitoring System microbarometer arrays that are being constructed as one of the verification measures for the Comprehensive Nuclear-Test-Ban Treaty. The results confirm those of Mack and Flinn (1971) that signal coherence is greater in directions parallel, and is less in directions perpendicular, to the direction of propagation. In contrast to earlier studies, we report larger inter-event variation in coherence structure and provide an assessment of how these findings may influence future microbarometer array design.
Interferometry applied to the large aperture infrasound array in the Netherlands
Authors: Fricke Julius , Evers Läslo , Wapenaar Kees , Simons Dick
Published: November 2013

It has been theoretically shown by Wapenaar (2006) that the non-reciprocal Green's function can be retrieved with cross-correlation. Thus, interferometric techniques can be applied to a moving medium such as the atmosphere. Numerical experiments have shown that the delay times of stratospherically refracted infrasound can be obtained from cross-correlation between pairs of microbarometers. Doing so, information about the wind and temperature around the stratopause can be passively gathered from the stationary phase with, for example, the continuous noise of microbaroms. Actual measurements have been used from the Large Aperture Infrasound Array (LAIA) in the Netherlands. LAIA consists of several microbarometers with inter-station distances ranging from a few kilometers to tens of kilometers and is ideally suited to assess the results from theoretical and numerical experiments in practice. Results will be shown on the correlation length of infrasound from microbaroms and the effect of wind and temperature on the delay times retrieved from cross-correlations.
Consistent Wentzel-Kramers-Brillouin (WKB) approximation for acoustic-gravity waves in the atmosphere
Authors: Godin Oleg A.
Published: November 2013

The ray and WKB approximations have long been important tools of understanding and modeling propagation of atmospheric waves. However, contradictory claims regarding applicability and uniqueness of the WKB approximation persist in the literature. Here, linear acoustic-gravity waves (AGWs) in a layered atmosphere with horizontal winds are considered, and a self-consistent version of the WKB approximation is systematically derived from first principles and compared to ad hoc approximations proposed earlier. Parameters of the problem that need to be small to ensure validity of the WKB approximation are identified. Properties of low-order WKB approximations are discussed in some detail. Contrary to familiar cases of acoustic waves and internal gravity waves in the Boussinesq approximation, the WKB solution contains the geometric, or Berry, phase. Put differently, knowledge of the AGW dispersion relation is not sufficient for calculation of the wave phase. Significance of the Berry phase is illustrated by its effect on resonant frequencies of the atmosphere for vertically propagating waves.
Reflection and transmission of low-frequency spherical waves at gas-liquid interfaces
Authors: Godin Oleg A.
Published: November 2013

High-frequency asymptotic solutions of the canonical problem of a spherical wave reflection at and transmission through a plane interface are well known. These asymptotics are usually derived using the stationary phase method and its extensions assuming that the distance between the point sound source and a receiver is large compared to the wavelength. The opposite case, where the distance is either of the order of or smaller than the wavelength, is of interest in a number of problems such as radiation of infrasound into the atmosphere by underwater explosions and earthquakes. Available quasi-stationary approximations fail to describe correctly acoustic power flux through the interface. Here, a low-frequency asymptotics of the acoustic field is obtained for gas-liquid interfaces. It is found that the acoustic field transmitted into gas can be approximately represented as a field due to a virtual point source in an unbounded medium. Positions of the virtual sources of the low- and high-frequency transmitted waves are compared. It is found that the bulk of acoustic energy transmission through the interface occurs at epicentral distances of the order of the source depth, regardless of the wavelength.
Analysis of air-ground coupling using seismo-acoustic cross-spectral analysis
Authors: Matoza Robin S. , Fee David
Published: November 2013

Air-ground and ground-air coupling are key processes in the rapidly developing field of seismo-acoustics and are particularly relevant in volcano geophysics. Volcanic eruptions often simultaneously generate sustained seismic and infrasonic signals, e.g., by fluid flow simultaneously occurring in the subsurface and atmosphere. Building upon recent work by Ichihara etal. (2012), we show that cross correlation, coherence, and cross-phase spectra between waveforms from nearly collocated seismic and infrasonic sensors provide new information about air-ground and ground-air coupling. Combining this method with infrasound array processing can provide insight into the geophysical processes generating a range of seismo-acoustic signals. For example, we show that seismic tremor recorded during an eruption at Mount St. Helens is dominated by air-ground coupled infrasound between 5 and 15 Hz. We anticipate that cross-spectral analysis and similar techniques will have wide applicability to arbitrary seismo-acoustic sources and in exploiting the growing volume of seismo-acoustic data. Ichihara et al. (2012), “Monitoring volcanic activity using correlation patterns between infrasound and ground motion,” Geophys. Res. Lett. 39, L04304, doi:10.1029/2011GL050542.
Numerical computation of acoustic radiation force in two and three dimensional resonators
Authors: Mercado Ari , McCarthy Brian , Ross-Johnsrud Ben , Dionne Jason , Lipkens Bart
Published: November 2013

Large scale acoustophoretic separation of particles in a flow field can be accomplished by trapping the particles, i.e., remain in a stationary position, in ultrasonic standing waves. The particles are collected in a column pattern, separated by half a wavelength. Within each nodal plane, the particles are trapped in the minima of the acoustic radiation potential. The axial component of the acoustic radiation force drives the particles to their stable axial position. The radial or lateral component of the acoustic radiation force is the force that traps the particle. It must be larger than the combined effect of fluid drag force, i.e., Stokes drag, and gravitational force. There is a need for a better understanding of the lateral acoustic radiation force in realistic acoustophoretic separation devices. COMSOL Multiphysics® software was used to predict the acoustic field in two and three dimensional models of acoustophoretic separation devices driven by piezoelectric transducers. The resulting acoustic field was then used to calculate the acoustic radiation force acting on a suspended particle in two and three dimensions by applying Gor’kov’s equation. Measurements of trapped particles in standing waves indicate accurate calculations of acoustic field and radiation force. [Work supported by NSF PFI:BIC 1237723.]
A kinematic shaker system for dynamic stabilization of Rayleigh-Bénard convection
Authors: Swaminathan Anand , Poese Matthew E. , Smith Robert W. , Garrett Steven L.
Published: November 2013

The ability to dynamically inhibit Rayleigh-Bénard convection using acceleration modulation is of interest to groups who design and study thermoacoustic machines, as the introduction of unwanted convection can have deleterious effects on the desired operation and efficiency of the device. These performance issues, caused by suspected convective instability, have been seen both in traveling wave thermoacoustic refrigerators and in cryogenic pulse tube chillers [Swift and Backhaus, J. Acoust. Soc. Am. 126, 2273 (2009)]. This presentation discusses the vibratory conditions under which a small, rectangular container of statically unstable fluid may be stabilized by vertical vibration, applying the computational methods of Carbo [Ph.D. Thesis, Penn State Univ. (2012)]. The required shaking velocities for stabilization are found to be too large for an electrodynamic shaker. As a solution, a shaker system employing a kinematic linkage to two counter-rotating flywheels, driven by a variable-speed electrical motor, produces peak-to-peak displacements of 15.24 cm to a platform mounted on two guide rails. Thus far, this shaker has produced peak speeds of up to 3.7 m/s. [Work supported by the Office of Naval Research, the ARL Walker Graduate Assistantship, and ARPA-E.]
Investigation of sound diffraction in periodic nano-structures using acoustic microscopy
Authors: Shaw Anurupa , Yoon Suk Wang , Declercq Nico F.
Published: November 2013

Acoustic microscopy is a well established technique as far as smooth surfaces are concerned. Traditionally V(z) curves are obtained from which, through surface wave generation, important features concerning elasticity and related properties can be extracted. More recently, high resolution imaging based on acoustic microscopy has appeared. In this study, we investigate the possibility to investigate samples with nano-structures.The surface profile of the samples have periodic structures but lack smoothness. The periodicity causes sound diffraction and the roughness influences the acoustic microscopic investigation. Small acoustic contrast between the substrate and the periodic corrugation materials give us information about the additional stresses which develop and affect the bonding between the two materials. In this presentation, a description is presented of the experiments and a comparison is made between results on smooth surfaces and results on periodic structures of the same material. An attempt is made to analyze the effects described above.
Acoustics-structure interactions in the human middle ear produce variety of motion modes at the malleus-incus complex
Authors: Cai Hongxue , Jackson Ryan P. , Steele Charles R. , Puria Sunil
Published: November 2013

We developed a 3D finite-element model to simulate the dynamics of the human middle ear, using COMSOL Multiphysics software to solve the resulting acoustics-structure interaction problem. We validated the model by comparing numerical results with experimental data measured in the ear canal, on the tympanic membrane (TM), at the umbo, and at the stapes footplate. The results show that at low frequencies (up to 500 Hz), the conventionally accepted hinge-like motion of the malleus-incus complex dominates the response, with the angle between the rotational axes of the malleus and incus staying below about 5 degrees. However, above 5 kHz, this angle becomes significantly larger, indicating that the malleus and incus rotate about different axes. Near the upper frequency limit of 20 kHz, the angle between the rotational axes of the malleus and incus approaches 90 degrees as the malleus adopts a lower-inertia twisting-like rotation about its first principal axis. The model is also used to explore the effects, on ossicular motion and overall pressure transfer from the ear canal to the cochlea, of alterations to the mechanical properties of the TM, to the flexibility of the malleus-incus joint, and to the mass of the ossicles. [Funded by NIDCD/NIH.]
Selective and divided attention: Spatial orienting in a semantic classification task
Authors: McCloy Daniel , Lee Adrian KC
Published: November 2013

Preliminary data from our lab using non-lexical stimuli (alphabet letters) suggests that auditory spatial attention may act as a filter with some spatial roll-off (seen in patterns of false alarms to targets in unattended spatial streams). The current project extends that research, examining the interaction between auditory spatial attention and lexical activation. In a semantic classification task, listeners respond to words of a target class only when they occur in designated spatial streams. Streams are temporally interleaved (in random spatial order) to minimize energetic masking. Given that tone-complex experiments suggest a short time course for exogenous spatial reorientations (at least 150 ms but less than 450 ms) [Roberts et al., J. Exp. Psychol. Human 35, 1178–1191 (2009)] when compared to lexical activation (~400 ms) [Pylkkänen et al., Brain Lang 81, 666–678 (2002)], we predict that the additional processing required for semantic classification could paradoxically reduce false alarms in spatial locations proximal to the target stream(s), by delaying the response decision beyond the temporal scope of the exogenous orienting response. We discuss findings in relation to models of exogenous/endogenous attention and lexical processing.
Towards a physical model of the berimbau: Obtaining the modal synthesis of the cabaza
Authors: Castellanos Macin Pablo , Smith Julius O.
Published: November 2013

The worldwide presence of Brazilian culture grows every day. However, some of the musical instruments used in its principal cultural activities lack of a formal acoustic analysis which would make them more understandable for the rest of the world. One of them is the berimbau-de-barriga (berimbau), which consists of a string (wire) attached to an arched rod and a resonance box called cabaza. Modeling the berimbau will not only open up possibilities for its application to other musical genres, but will also allow the incorporation of its characteristics into new virtual instruments. The present work describes the modal synthesis of the cabaza, i.e., modeling this sounding box as a parallel bank of digital resonators. Impulse response measurements were obtained using a force hammer, and second-order resonator frequency-responses were fit to the data using Matlab.
The perception of Mandarin lexical tones by native Japanese and Thai listeners
Authors: Tsukada Kimiko , Roengpitya Rungpat , Xu Hui Ling , Xu Nan
Published: November 2013

Mandarin differentiates four tones (T1: high level (ā), T2: high rising (á), T3: dipping (ǎ), T4: high falling (à)). Learning these lexical tones is known to be difficult for those from non-tonal language background (e.g., English). What about listeners with no knowledge of Mandarin but have varying experience with tones or pitch variation? This study examined the discrimination of 6 Mandarin tone contrasts (T1-T2, T1-T3, T1-T4, T2-T3, T2-T4, and T3-T4) by native speakers of Japanese (pitch-accent language) and Thai (tonal language). The listeners’ tone discrimination accuracy was assessed in a categorical discrimination test developed by Jim Flege and colleagues. Both non-native groups were less accurate than the native group, in particular, for the T1-T2, T1-T3, T1-T4, and T2-T3 contrasts. Despite using lexical tones in their first language (L1), Thai listeners did not have a distinct advantage over Japanese listeners and the two groups showed a similar pattern of results. Overall, discrimination accuracy of contrasts involving T1 was lower than other contrasts with the exception of T2-T3. Both Japanese and Thai listeners had greatest difficulty with T2-T3. Since previous knowledge of L1 tones may interfere with the perception of non-native tones, these results will be discussed with reference to a Thai tonal system.
Training effect on the second language learning for young learners using computer-assisted language learning system: Quantitative consideration on relationship among speech perception of the second language, learning experience and amounts of learning
Authors: Ikuma Yuko
Published: November 2013

Longitudinal training experiment was conducted in order to examine the relation between the perceptual ability of English as a foreign language and amount of learning experiences beyond schools targeting Japanese elementary school students. Over four hundred students among the 3rd grade through 6th grade participated in this study. Three hundred and thirty-two students of them had learning experience beyond school, and the other, 134 students, did not. Students spent approximately 10 h of individualized computer-based training that focused on intensive auditory input. The result of t-test showed that the scores of the group of students who have previous learning experience exceeded the scores of the students in the other group at the beginning; however, at the end of the period, it revealed from the result of ANOVA that students without learning experience before starting learning English at school improved their sensitivity on perception of English syllable and some phonemes much more than the experienced. These results suggest that the appropriate perception training utilizing the auditory input is effective in cultivation of aural comprehension. Implications for foreign language education for young learners will be discussed. [Work supported by JSPS KAKENHI Grant-in-Aid for Young Scientists (B) 23730832, Japan.]
The effects of dialectal differences on the identification of English vowels by native and nonnative listeners
Authors: Nozawa Takeshi
Published: November 2013

This study attempts to investigate how dialectal differences of English affect the identification of English vowels by native and nonnative speakers of English. Served as listeners were native speakers of New Zealand English and Japanese. They heard and identified /i, ɪ, eɪ, ɛ, æ, ɑ, ʌ/ uttered by native speakers of New Zealand and American English. Repeated-measures ANOVAs were performed, respectively, for each listener group. The results revealed that there was no significant main effect of dialect (p = 0.013), but a main effects of vowels was found significant (p≺0.001). An interaction between dialect x vowels was also significant (p≺0.001). Pairwise comparisons revealed that NZ listeners identified NZ English /ɪ/, /ɑ/, /ʌ/ better than AM English counterparts (p≺0.05), but they identified AM English /æ/, /ɛ/ better than NZ English counterparts (p≺0.05). Native Japanese listeners, on the other hand, identified AM English vowels significantly better than NZ English vowels (p≺0.001). Particularly, they identified /i, ɪ, ɛ, æ/ uttered by AM English talkers than those uttered by NZ English talkers. However, native Japanese listeners identified NZ English /ɑ/ better than American English counterpart(p≺0.05).
Effects of listener characteristics on foreign-accentedness rating of a non-standard English dialect
Authors: Morales Andrea , Warner Natasha
Published: November 2013

This project analyzes what characteristics of listeners affect whether they perceive Chicano English as foreign-accented English. Many Americans assume Chicano English (CE) is non-native English spoken by native Spanish speakers, but CE is often spoken as a native dialect of English. CE is a very common dialect in Tucson, Arizona, and this project examines the correlation between listeners' ethnicity, familiarity with Hispanic people, and political stance on immigration, and their perception of CE as foreign-accented. Stimuli are sentences read by CE and other Tucson speakers that contain phonetic environments where CE has features that distinguish it from Standard American English (SAE). The listener population is Southern Arizonans of various ethnicities with varying degrees of exposure to CE and Spanish. The experiment uses a Foreign Accentedness Rating (FAR) task, as well as classification of stimuli as spoken by a Hispanic vs Anglo speaker and background questions on listeners' language background and political opinions. Highly accurate identification of ethnicity is predicted, as well as correlations between some measures of the listeners' background and strength of FAR rating of CE speakers. Conclusions involve the effect of long-term exposure to a local dialect and sociolinguistic status on perceived degree of foreign accent
Effect of native Mandarin dialects on English learners’ use of prosodic cues to stress
Authors: Qin Zhen , Tremblay Annie
Published: November 2013

Second-language learners (L2ers) weight phonetic cues to stress as a function of how these cues are used in the native language. This study investigates the effect of native dialects on the use of prosodic cues (F0 and duration) to English stress by native speakers (NSs) of Standard Mandarin (SM), Taiwanese Mandarin (TM), and English. Both TM and SM use F0 to realize lexical tones, but only SM uses duration to realize lexically contrastive stressed-unstressed vs stressed-stressed words. English NSs and intermediate-to-advanced TM-speaking or SM-speaking L2ers of English (at the same English proficiency) completed two sequence-recall tasks. In each trial, they heard four English non-words with trochaic and iambic stress, and pressed “1” and “2” to recall them in the correct order. In Experiment 1, participants heard natural stimuli (converging F0 and duration cues); in Experiment 2, the stress stimuli were resynthesized to contain only F0 cues, only duration cues, converging F0 and duration cues, or conflicting F0 and duration cues. In Experiment 1, all groups used naturally produced stress to recall English non-words. In Experiment 2, SM-speaking L2ers used duration more than TM-speaking L2ers to recall English non-words. Native dialect is suggested to be considered in L2 speech processing models.
Predicting code-switches from phonetic information: The discourse marker like in Spanish-English code-switching
Authors: Piccinini Page E.
Published: November 2013

The present study investigated whether Spanish-English bilinguals (L1 Spanish, English dominant) use phonetic cues to anticipate code-switches. Listeners were presented with four sets of 10 utterances. In a given set all utterances began in English or Spanish. All utterances included the discourse marker like. In each set, half of the utterances continued in the same language after like and half switched languages after like. Listeners only heard up to and including like. Listeners evenly sorted the utterances into two columns, “continues in English” or “continues in Spanish,” to indicate which five utterances involved code-switching. Half of listeners received instructions in English and half in Spanish. Both sets of listeners were significantly above chance for stimuli beginning in English [p < 0.05]. Listeners who received Spanish instructions were also trending above chance for stimuli beginning in Spanish [p = 0.08]. This suggests listeners can use phonetic cues to anticipate switches from their dominant to their non-dominant language. Additionally, when language mode is the non-dominant language, listeners can also anticipate switches from their non-dominant to their dominant language. These results support a theory where both languages are somewhat activated at all times, allowing bilinguals to use phonetic cues to anticipate language switches.
Perception of English narrow and broad focus by native speakers of Mandarin Chinese
Authors: Wayland Ratree , Guerra Chelsea
Published: November 2013

The aim of this study is to examine the ability to accurately perceive and comprehend English intonation patterns among native Mandarin speakers. Intonation patterns are patterns of rising and falling in pitch over the course of a full utterance. Both English and Mandarin make use of intonation patterns. However, unlike English, Mandarin is a tonal language in which pitch changes served to distinguish word meaning. The tonal patterns of words thus cause additional pitch fluctuation in the overall intonation of a Mandarin sentence. Sixteen Mandarin and 12 English speakers participated in the study. In the first task, participants were asked to listen to English sentences with either a falling or a rising intonation, and to decide whether the sentence is complete or incomplete. Participants’ comprehension of English sentences produced with an intonation pattern focused on the verb, the noun or the entire sentence was examined. The results obtained indicated that (a) native speakers of English outperformed native Mandarin speakers on both tasks, that (b) both groups performed better on the second task, and that (c) the difference between the two tasks was greater among Mandarin speakers than among English speakers.
Prosodic profile of American Aviation English
Authors: Trippe Julia , Pederson Eric
Published: November 2013

Aviation English (AE) is under scrutiny due to miscommunication between international pilots and controllers. To enhance public safety, since 2011, aviation professionals must prove technical and practical English proficiency. Previous studies measure AE speech accuracy by task performance and repeated elements (Barshi and Healy, 2011), and speech comprehensibility using native speaker judgments (Farris et al., 2008). The current study develops a quantifiable index for evaluating AE production based on prosody. Reasonably fluent prosody is critical to language comprehensibility generally, but since AE has no predictable intonation due to signal limitations, lack of function words, standard phraseology and rapid speech rate, we are specifically developing a rhythm profile of Native Speaker AE (NSAE) to evaluate Non-native Speaker AE production and model training methods for different first language (L1) prosodic types. We are training a speech aligner on tapes of US controllers to calculate a baseline for American NSAE. Our index will be generated using known metrics such as delta-V/C, %V (Ramus, 2000), PVI (Low et al., 2000), and varcoV/C (Dellwo, 2006). Since AE is derived from “stress-timed” English to be standardized and predictable, we predict that AE will exhibit a rhythmic signature comparable not only to English but to “syllable-timed” languages.
BTBD3 Controls Dendrite Orientation Toward Active Axons in Mammalian Neocortex
Authors: Matsui Asuka , Tran May , Yoshida Aya C. , Kikuchi Satomi S. , U Mami , Ogawa Masaharu , Shimogori Tomomi
Published: November 2013

Neuronal Activity and Dendrite Development

How does the developing brain establish the correct connections?

Matsui
et al.

(p.
1114
, published online 31 October) discovered an activity-dependent transcription mechanism during mouse and ferret visual cortex development that controls the direction of dendrite orientation, allowing dendrites to steer toward active axons and away from inactive axons. This mechanism enables the construction of polarized neuronal shapes for integration into neural circuits with the required finescale architecture to process subtle activity patterns, a property underlying complex behavior.
The Human Language–Associated Gene SRPX2 Regulates Synapse Formation and Vocalization in Mice
Authors: Sia G. M. , Clem R. L. , Huganir R. L.
Published: November 2013

Building Vocalization

The transcription factor FoxP2 (forkhead box P2) affects language acquisition in humans and regulates the protein SRPX2 (sushi repeat-containing protein X-linked 2), which itself also affects language.

Sia
et al.

(p.
987
, published online 31 October; see the Perspective by

Lieberman

) found that in the mouse brain, the FoxP2 transcription factor binds to the
SRPX2
gene. In tissue culture experiments, FoxP2, but not SRPX2, affected dendritic morphology, while both FoxP2 and SRPX2 affected the formation of excitatory synapses. Overexpression of SRPX2 in the mouse brain equivalent of the human brain's language area affected synapse density and disrupted the ultrasonic vocalizations emitted by mouse pups in search of their mothers.