bluuebunny/crossref_metadata_2025 huggingface dataset:
Sentence durations and accentedness judgments
Authors: Bond Z. S. , Stockmal Verna , Markus Dace
Published: October 2013

Talkers in a second language can frequently be identified as speaking with a foreign accent. It is not clear to what degree a foreign accent represents specific deviations from a target language versus more general characteristics. We examined the identifications of native and non-native talkers by listeners with various amount of knowledge of the target language. Native and non-native speakers of Latvian provided materials. All the non-native talkers spoke Russian as their first language and were long-term residents of Latvia. A listening test, containing sentences excerpted from a short recorded passage, was presented to three groups of listeners: native speakers of Latvian, Russians for whom Latvian was a second language, and Americans with no knowledge of either of the two languages. The listeners were asked to judge whether each utterance was produced by a native or non-native talker. The Latvians identified the non-native talkers very accurately, 88%. The Russians were somewhat less accurate, 83%. The American listeners were least accurate, but still identified the non-native talkers at above chance levels, 62%. Sentence durations correlated with the judgments provided by the American listeners but not with the judgments provided by native or L2 listeners.
Evaluating causes of foreign accent in English sentences spoken by native speakers of Italian differing in age of arrival (AOA) in Canada
Authors: Flege James , MacKay Ian , Imai Satomi
Published: October 2013

This study evaluated potential causes of foreign accent (FA) by including native Italian (NI) speakers with a later age of arrival (AOA) in Canada than in previous studies. Three NI groups (n=18 each) differing in AOA (means=10, 18, and 26 years) participated. Listeners used a 9-point scale to rate sentences produced by the three NI groups and native English controls. The ratings obtained for all four groups differed significantly. The stronger foreign accents of the AOA-18 than AOA-10 group might be attributed to the passing of a critical period, or to stronger cross-language interference by more robust Italian phonetic categories. The difference might also be attributed to differences in language use. This is because the AOA-10 and AOA-18 groups (but not the AOA-18 and AOA-26 groups) differed significantly in percentage of English and Italian use, length of residence in Canada, and years of education in Canada. None of these explanations will apparently explain the stronger FAs of the AOA-26 than AOA-18 group. The difference between these groups might be attributed to cognitive aging [Hakuta et al., Appl. Psycholinguistics (in press)], which results in gradually less successful second-language acquisition across the adult life span. [Work supported by NIH.]
Vowel spacing in four-vowel systems
Authors: Maddieson Ian
Published: October 2013

Languages with fewer than average vowel quality contrasts provide a testbed for proposed universals of vowel systems. This paper examines the positioning in two- and three-formant acoustic spaces of the vowels of several languages with four contrastive vowel qualities. All have vowels like /i/ and /a/, with /i/ seeming the most similar across the languages. Most have a back rounded vowel with a higher F1 than that of /i/, resulting in the transcription /o/ rather than /u/. The position of the fourth vowel is highly variable. In San Carlos Apache it is a front mid vowel, in Shipibo a high central-back vowel, and in Paiwan a mid central vowel. The overall maximal separation of vowels in the acoustic space is therefore not the major organizing principle of these vowel systems. Rather, their construction is anchored by the polarity of /i/ vs /a/ (dispersed spectral energy versus compact mid-frequency energy). A high back vowel with close rounding is the next most distinct vowel in terms of spectral energy distribution. But this is avoided, perhaps because vowels of this type have attenuated amplitude, and a lower vowel is preferred. The fourth vowel is free to take a variety of characteristics.
Effects of the propagation environment on coherence of underwater broadband acoustic signals
Authors: Romond Rachel , Bradley David L. , Culver R. Lee
Published: October 2013

Acoustic and environmental measurements were performed in 550 m of water approximately 2500 m east of San Clemente Island, California over a four-day period in August 2002. Continuous wave and frequency modulated pulses with center frequencies of 20 kHz to 40 kHz were transmitted over a 700 m distance underwater. Four projectors were located between 10 m and 70 m deep, and five receivers were positioned between 45 m and 220 m deep. Data from an anemometer, wave rider buoy, acoustic Doppler current profiler and towed conductivity–temperature–depth array were recorded simultaneously over the test period to characterize the marine environment. The extensive set of environmental data provided a basis for boundary condition and water column characterization. These conditions were input into a propagation model to predict the acoustic signal structure and propagation behavior in the measured environment. Predictions of acoustic propagation parameters will be compared to results from on-site acoustic measurements. [Work supported by ONR under Award No. N00014-02-1-0156.]
Tilt angle dependence of backscattering enhancements from organ pipe modes of open water-filled cylinders: Measurements and models
Authors: Osterhoudt Curtis F. , Marston Philip L.
Published: October 2013

A simple target for simulating narrow low-frequency resonances of cylinders is an open metal pipe completely filled with water. We have previously described how the high-Q organ-pipe modes having a pressure node near each end are easily observed in backscattering experiments with small cylinders [C. F. Osterhoudt and P. L. Marston, J. Acoust. Soc. Am. 110, 2773 (2001)]. The resonance occurs because of the strong reflection of internal acoustic waves from the open ends of the pipe [H. Levine and J. Schwinger, Phys. Rev. 73, 383–406 (1948)]. In the present research, the dependence of the backscattering amplitude on the orientation of the cylinder is measured and modeled. The tilt angle dependence is affected by the symmetry of the organ pipe mode. An approximation was also developed for the backscattering amplitude at high Q resonances based on energy conservation, reciprocity, and the optical theorem. While this analysis applies to cylinders suspended in water away from boundaries, the organ-pipe modes studied may be useful for investigating scattering processes for buried or partially buried cylinders. [Research supported in part by ONR.]
Energy redistribution speech intelligibility enhancement, vocalic and transitional cues
Authors: Harris John G. , Skowronski Mark D.
Published: October 2013

Two novel speech enhancement algorithms are presented that automatically increase intelligibility in noisy environments while maintaining the signal power and naturalness of the original speech. These energy redistribution (ER) algorithms move signal energy to targeted regions of relatively high information content that are crucial for intelligibility. The boosted regions are originally of low energy and therefore usually the first segments lost with the addition of environmental noise. The ER voiced/unvoiced (ERVU) method transfers energy from voiced speech to regions of unvoiced speech, while the ER spectral transition (ERST) method moves energy from spectrally stationary regions to spectrally transitional regions. Hand-held cell phones and public address systems are expected to be the dominant applications for these techniques. Standard noise reduction methods such as spectral subtraction are assumed to have already been applied to the voice signal before broadcast. Using human listening tests, it was found that both algorithms boost the intelligibility of speech in noisy environments by nearly 7% over the original unprocessed signals, without degrading naturalness or increasing signal power. Furthermore, both algorithms allow for controlling the trade-off between boost gain and speech naturalness.
Foam rheology in the wet and dry limits
Authors: McDaniel J. Gregory , Holt R. Glynn , Akhatov Iskander Sh.
Published: October 2013

Understanding the rheological behavior of wet foams is important as a basic problem in fluid physics, and as a practical problem in many industries. This lecture will describe research into the wet and dry limits of foam rheology by a relatively new experimental technique in which foam drops are acoustically levitated and driven into motion. In the dry limit, the drops behave as viscoelastic solids. The effective moduli of the foam are estimated by observing the resonances of the drops and matching them to an analytical model for viscoelastic sphere vibrations. Analytical explorations of the wet limit have proceeded by considering the dynamics of a single bubble in a volume of liquid determined by the foam’s void fraction. The linearized result is a wave equation, from which the natural frequencies and mode shapes of wet foam drops are determined. Relationships between this wave equation and those of classical effective medium theories will be described. [Work supported by NASA.]
ClassTalk system for predicting and visualizing speech in noise in classrooms
Authors: Hodgson Murray
Published: October 2013

This paper discusses the ClassTalk system for modeling, predicting and visualizing speech in noise in classrooms. Modeling involves defining the classroom geometry, sources, sound-absorbing features, and receiver positions. Empirical models, used to predict speech and noise levels, and reverberation times, are described. Male or female speech sources, and overhead-, slide-, or LCD-projector, or ventilation-outlet noise sources, can have four output levels; values are assigned based on ranges of values found from published data and measurements. ClassTalk visualizes the floor plan, speech- and noise-source positions, and the receiver position. The user can walk through the room at will. In real time, six quantities—background-noise level, speech level, signal-to-noise level difference, useful-to-detrimental energy fraction (U50), Speech Transmission Index, and speech intelligibility—are displayed, along with occupied and unoccupied reverberation times. An example of a large classroom before and after treatment is presented. The future development of improved prediction models and of the sound module, which will auralize speech in noise with reverberation, is discussed.
Propagation through a stratified ocean wave guide with random volume and surface inhomogeneities, Part I. Theory: Attenuation, dispersion, and acoustic mirages
Authors: Ratilal Purnima , Makris Nicholas C.
Published: October 2013

Analytic expressions for the mean field propagated through a stratified ocean with random volume or sufrace inhomogeneities of arbitrary size compared to the wavelength are derived from a wave guide scattering model stemming from Green’s theorem. It is found that multiple scattering through inhomogeneities in the forward direction can be succinctly expressed in terms of modal attenuation and dispersion coefficients under widely satisfied conditions. The inhomogeneities can have an arbitrary distribution in depth so that the model can realistically apply to scattering from internal waves, bubbles, fish, seafloor and seasurface roughness as well as sub-bottom anomalies. An understanding of the coherence of the forward scattered field can be gained by analogy with the formation of optical mirages in low-grazing angle forward scatter from random surfaces.
A multipole method for computation of acoustics of a convex polyhedral room
Authors: Gumerov Nail A. , Duraiswami Ramani , Zotkin Dmitry N. , Davis Larry S.
Published: October 2013

The classical method for constructing room impulse responses (Allen and Berkeley, 1979) works for the case of rectangular rooms, and for general polyhedral rooms heuristic techniques are used. A new method for computation of the room impulse response of a general polyhedral room is presented. The method is based on the decomposition of the acoustic field into a free field and a sum of fields caused by interaction with the walls. These are modeled using a few multipole sources located outside the room. First a solution is developed for the case when the room is convex, and the walls are sound hard. Here the solution can be obtained using symmetry conditions for the multipoles re-expanded at proper locations. Using multipole translation theory, and truncation, a closed system of linear equations for the expansion coefficients is obtained, which can be solved to obtain the room impulse response. The method is then generalized to include wall impedances, by using linear differential transforms of multipole solutions. The method is validated by comparison with known solutions based on the image method for particular cases, and listening tests. [Work supported by NSF.]
Behavioral responses to acoustical stimulation of individuals and colonies of the termite Reticulitermes virginicus
Authors: Chambers JulieAnn M. , Hasse Roger
Published: October 2013

This study examined the effects of acoustical stimulation on Reticulitermes virginicus termites and describes the results of experiments conducted to analyze behavioral responses to various frquencies of sound. Termites were studied for individual response to sound stimulation and for colony response. Individuals were mounted to rods and responses were recorded to sound stimulations and magnetic vibrations. Colonies were established and allowed to acclimate in simulated nesting environments containing fine porous sand and rotten wood shims. A transducer was buried in the sand close to the colony and driven by a function generator using variable frequencies at fixed amplitude. Two types of sound stimuli were applied to each colony: tone bursts (TB) and continuous waves (CW). Behaviors indicated that the termites were agitated by the sound stimulus and termite activity was interpreted as an avoidance response. Once stimuli were removed the termites returned to normal activity near the aquarium walls. Observed responses are being examined for consistency and characterization of behaviors. Further study to be presented will quantify the nature of acoustic transmission in the aquaria as well as to understand the termite responses to separate aspects of the stimuli.
Environmental measurements and mid-frequency backscatter in shallow water
Authors: Tang Dajun
Published: October 2013

To understand bottom backscattering mechanism at the mid-frequency range (nominally 3.5 kHz), direct measurements of bottom roughness and sub-bottom heterogeneity were made along with concurrent backscatter measurements in a shallow water site with 105 m water depth. The backscatter was recorded on a vertical line array with 31 elements with a 3.5 kHz source attached at the bottom of the array. Bottom roughness and sub-bottom heterogeneity were measured using an in situ conductivity probe. The roughness measurements cover a one-dimensional profile of approximately 4 m in length with vertical resolution of 4 mm and horizontal resolution of 1.5 to 2.5 cm. Heterogeneity measurements cover a depth of 5 to 10 cm. Ambient noise received by the vertical line array was used to estimate the sound speed, density, and attenuation coefficient of the surficial sediments. A Monte Carlo modeling capability was developed to extensively simulate the backscatter with different environmental inputs. The results of this effort covering all three areas of acoustics, environments, and modeling will be reported.
Travel time bias at sound reflection from an uneven surface: Implications for ocean remote sensing
Authors: Godin Oleg A. , Fuks Iosif M.
Published: October 2013

Travel time is the acoustic quantity which is most frequently used to infer physical properties of the ocean or its bottom from acoustic measurements. Ocean boundaries typically have a complicated shape with smaller-scale features normally described as random roughness. The roughness translates into fluctuations of reflected acoustic arrivals. In this paper, statistical properties of acoustic travel time are considered in homogeneous and a vertically-stratified 3-D ocean with rough boundaries and interfaces. On average, the rough surfaces can be either horizontal planes, corresponding to the ocean surface, or deterministic curved surfaces, corresponding to the sea floor or interfaces within the ocean bottom. It is shown that mean acoustic travel time differs from the travel time in an average medium. In particular, in agreement with Fermat’s principle, small cross-range slopes of the reflecting surface always decrease ray travel time. The travel time bias is studied using the ray and the adiabatic normal mode theories. Implications are analyzed of the travel time bias on interpretation of measurements made with echo sounders, inverted echo sounders, and tomography systems employing surface- and/or bottom-reflected arrivals. [Work supported by ONR.]
Measurement of the time evolution of Rayleigh streaming in high-amplitude standing waves
Authors: Thompson Michael W. , Atchley Anthony A.
Published: October 2013

The time evolution of the axial component of the Rayleigh streaming velocity field in a cylindrical, air-filled resonator has been measured using laser Doppler anemometry. At low acoustic amplitudes, the measured field is in agreement with classical theory. The axial component varies sinusoidally along the axial direction and quadratically along the radial direction, and the position of maximum streaming velocity on the axis is located midway between the velocity node and velocity antinode. At higher acoustic amplitudes, the streaming velocity field initially resembles the classical result, but becomes progressively distorted as time passes. The position of maximum streaming velocity on the axis shifts towards the velocity antinode, while the streaming velocity outside the boundary layer, near the resonator wall, remains unaffected. Additionally, the radial dependence of the axial streaming velocity deviates from its initially parabolic shape, becoming flatter near the velocity node and steeper near the velocity antinode. The length of time required for the streaming to reach steady state is on the order of several minutes for a fundamental frequency of 310 Hz, a resonator radius of 23 mm, and an antinodal acoustic velocity of 6.0 m/s peak. [Work supported by ONR.]
Diffraction tomography applied to simulated ultrasound through breast tissue
Authors: Chambers David H.
Published: October 2013

Diffraction tomography is used to obtain images of sound speed and attenuation of a slice of breast tissue obtained from the Visible Woman data set. Simulated ultrasound data was generated using an acoustic propagation code run on the ASCI Blue Pacific computer at Lawrence Livermore National Laboratory. Data was generated for a slice of healthy tissue, and a slice with simulated lesions to determine the ability of the imaging method to detect various abnormalities in the breast. In addition, the time reversal operator for the slice was constructed from the data and the eigenfunctions backpropagated into the slice as first suggested by Mast [Mast, Nachman, and Waag, J. Acoust. Soc. Am. 102(2)] to identify structures associated with each time reversal mode for both the healthy tissue and tissue with lesions.
Nonsense syllable perception by monolingual and bilingual English speakers
Authors: Rogers Catherine L. , Brea-Spahn Maria R. , Tam Mei-Wa , Nyang Edna E.
Published: October 2013

Understanding speech in demanding environments is essential for daily communication. Previous research has shown that even highly proficient bilinguals may experience greater difficulty than monolinguals in understanding speech in noise. In the present study we further address this issue by examining the effects of varying task demand, fatigue, and practice on speech perception by bilinguals. One group of monolingual English listeners and three groups of Spanish–English bilinguals (bilingual since childhood, bilingual since teenager, and bilingual since adulthood) listened to nonsense syllables presented in noise and at increasing presentation rates. Listeners twice completed the two speech perception tasks on two days of testing. On one day the speech tasks were preceded by and on the other day followed by approximately 40 minutes of testing on nonspeech auditory tasks. Monolingual and bilingual listeners’ overall performance, their performance across the two days of testing (practice effect), and their performance across test orders (fatigue effect) will be compared. Preliminary results from two monolingual and two highly proficient bilinguals (bilingual since age 16 or earlier) show similar overall performance on both speech tasks and no effect of fatigue (test order), but suggest a greater practice effect for bilinguals’ perception of syllables in noise.
Formulas for signal and reverberation with mode-stripping and Lambert’s law
Authors: Harrison Chris H.
Published: October 2013

Extending David Weston’s notion of ray invariants and flux it is possible to derive closed-form solutions for two-way propagation and reverberation in range-dependent ducts. In particular, there is interesting and sometimes surprising behavior when the propagation obeys ‘‘mode-stripping’’ (the high angles are preferentially attenuated by bottom losses) while the scattering obeys Lambert’s Law (high angles are preferentially backscattered). There is a regime where reverberation and target follow the same range law, postponing ‘‘reverberation-limiting’’ indefinitely! From the experimental and databasing point of view it is therefore extremely important to know whether Lambert’s Law is actually obeyed in practice. These issues and their implications for signal-to-background are addressed. The formulas allow for range-dependent environments and the transition from mode-stripping to single mode propagation at long range. A modified version for range-independent environments includes the effects of refraction on reverberation and signal-to-background. While these formulas cannot compete with numerical calculations in terms of detail, they show at a glance the dependence on such parameters as bathymetry, critical angle, bottom loss (within the critical angle). Here, the behavior is illustrated graphically and compared with a numerical model, SUPREMO.
System-orthogonal functions for sound velocity profile perturbation
Authors: Xu Wen , Schmidt Henrik
Published: October 2013

Empirical orthogonal functions (EOFs) are derived from direct measurements of the sound velocity profile (SVP) and they are orthogonal in regard to the statistics of the SVP uncertainty. Viewed from the sonar output end, however, the effect of an error in one EOF is usually coupled with the effect of the error in another due to the nonlinear physical constraints. Thus the traditional EOF is not an optimum basis set to characterize the SVP uncertainty in regard to sonar performance measure. To obtain a system-orthogonal SVP representation, a new set of orthonormal functions is derived for SVP perturbations in a water column. The performance measure used is the Cramer–Rao bound (CRB) for SVP expansion coefficients, and a full-field random Gaussian signal model is assumed. The derived functions make the CRB matrix diagonal, decoupling the errors in the estimation of the expansion coefficients. Compared to the traditional EOFs, the new set of SVP basis functions depends on both the statistics of the sound speed uncertainty and the sound waveguide propagation property. It also includes the noise effect in measurements. Using this system-orthogonal function set makes possible the investigation of the relative significance of the individual basis functions. [Work supported by ONR.]
Modeling the sensitivity of sediment backscattering measurements to the underlying variability of the sediment bulk environmental characterizations and inhomogeneity spectra
Authors: LePage Kevin D. , Holland Charles W. , Schmidt Henrik
Published: October 2013

A significant part of the uncertainty in reverberation predictions for shallow-water environments lies in the variability of the scattering strength associated with the bottom sediments. In this paper we evaluate how variability in the background properties of these sediments, and the characterizations of the inhomogeneity distributions within these sediments is propagated through to uncertainty in the sediment scattering strength. We also address the uncertainty in the measurement problem, i.e., how precise is the determination of the sediment bulk and inhomogeneity properties from local measurements of the time-angle evolution of bottom backscatter. We take as an example an environmental characterization obtained for a site on the Malta Plateau, south of Sicily. Here both the reflection properties of the seafloor and the time-angle evolution of the backscatter have been used to generate a notional environmental characterization of the bulk and inhomogeneity spectra of the bottom. We use the OASES volume scattering model to address the sensitivity and uncertainty issues surrounding the interpretation of this data set and to address the implications on the resulting reverberation uncertainty. [Work supported by the ONR Capturing Uncertainty DRI.]
Bistatic reverberation benchmarking exercise: BiStaR versus analytic formulas
Authors: LePage Kevin D. , Harrison Chris H.
Published: October 2013

The newly developed BiStaR range-dependent bistatic reverberation model is benchmarked against analytic formulas for bistatic reverberation intensity in range-dependent environments. The BiStaR model is based on the C-SNAP range-dependent normal mode propagation model with a narrow-band approximation time domain extension and a coherent patch interaction model. The code is also capable of producing incoherent reverberation predictions that here are directly compared to the analytic formulas. The analytic formulas have been derived using ray-based intensity formulas for propagation in range-dependent waveguides and a generalized class of Lambert law type scattering kernels. Comparison between the BiStaR and the analytic predictions show good agreement for a variety of range-dependent bistatic scenarios. Such agreement generates confidence in the closed form formulas, which are particularly valuable for generating insight into the simple mechanisms which control the dominant characteristics of range-dependent bistatic reverberation, and in the BiStaR model, which has been developed to model bistatic reverberation in 3-D environments with high resolution environmental characterizations. [Work supported by ONR and NATO SACLANT Undersea Research Centre.]
The control of rocket fairing interior noise with a networked embedded system
Authors: Frampton Kenneth D.
Published: October 2013

Numerous investigations have been conducted with the purpose of attenuating the acoustic environment within rocket payload fairings. These, to date, theoretical and experimental laboratory studies have demonstrated a great deal of success. However, practical applications to this, and other large-scale noise control problems, have been limited in their success. These limitations are due to nonscalable control systems, weight constraints and complexity. This work seeks to address these limitations by investigating the use of an array of networked embedded processors to control the interior acoustics of a rocket fairing. This networked embedded system consists of numerous computationally elements, paired with appropriate sensors and actuators, that communicate with each other over a wired or wireless network. The goal of the network is to minimize the interior acoustic level while expending a minimum amount of energy. Results from the simulation of such a control system will demonstrate the effectiveness of such an approach. These results will also be compared with those obtained by traditional, centralized control architectures.
Fluctuations in acoustic transmissions when propagation is at an oblique angle to the direction of oceanic tides
Authors: George Jacob , Field Robert L.
Published: October 2013

Ocean tides such as the lunar M2 tide in coastal regions cause time variations (also range variations) in water depth as well as sound speed profile. When acoustic transmissions are perpendicular to the direction of the tide the received signal exhibits the fundamental oceanographic frequency of the tide and overtones of the fundamental. When the transmissions are along the direction of the tide or at an oblique angle over a range spanning several tidal wavelengths, some reduction in fluctuations can be expected from general theoretical considerations. This phenomenon is studied using the adiabatic mode/WKB model, and the implications for coastal regions are discussed. For example, in SWAT data, the tidal phase remains constant over a 10 km range span along the tidal wave-front, but undergoes change over a similar range span along the tidal direction. Several illustrative examples are presented to show both the magnitude and complexity (relevant to overtone structure) of the acoustic fluctuations. [Work supported by ONR (PE-62435N), and administered by NRL.]
Speaker recognition using dynamic synapse based neural networks with wavelet processing
Authors: George Sageev , Berger Theodore , Dibazar Alireza , Yamada Walter
Published: October 2013

We have designed systems utilizing a dynamic synapse neural network (DSNN) to perform speech recognition tasks. The DSNN architecture has demonstrated noise-resistive properties in previous research. The speech signal is first passed through a bank of bandpass filters. The output of each filter then undergoes wavelet transformation to extract speaker-dependent features. Transformed signals are used as input for a DSNN, which is trained using a genetic algorithm training method. We are seeking to explore the capabilities of a biologically based neural network in solving a problem which humans are still better at solving than conventional solutions. The dynamic synapse neural networks were trained to perform several speech recognition tasks, including speaker verification, speaker identification, and word recognition. In the speaker verification task, the objective was to distinguish one speaker from a group of up to 22 imposters based on the utterance of a codeword. In the speaker identification task, the objective was to identify which of 6 speakers has uttered the codeword. In the word recognition task, the objective was to perform speaker-dependent word recognition on a set of 30 words. Neural networks were capable of 90% correct identifications in the presence of white noise (0 dB SNR).
Source bearing estimation using ice-mounted geophones
Authors: Dosso Stan , Vinnins Michael , Heard Garry
Published: October 2013

This paper presents the results of Arctic field trials carried out to estimate the bearing to acoustic sources in the water column using seismo-acoustic particle motion measured at a tri-axial geophone mounted on the sea ice surface. Source bearings are estimated by applying polarization filters to suppress seismic wave types with transverse particle motion, and computing the incident power rotated into radial look angles from 0–360 deg. The 180-deg ambiguity inherent in this rotational analysis is resolved by requiring prograde particle motion in the radial-vertical plane. Results are presented for smooth and rough annual ice and multiyear ice for source ranges from 200 m to 50 km. The results indicate good bearing estimation to long ranges with little dependence on ice type.
The ‘‘Zwislocki effect’’ in my work with cochlear implants
Authors: Chatterjee Monita
Published: October 2013

Joe Zwislocki’s uniqueness as a scientist lies in his ability to transcend methodology, sensory modality, or system—he has spanned the realms of mathematics, engineering, physics, physiology, and psychophysics to study hearing, touch, and vision. As a graduate student, I was amazed and inspired by his unerring ability to find unifying patterns underlying seemingly different phenomena. I became interested in cochlear implants while a graduate student in Joe’s lab. Cochlear implants present a unique opportunity to the sensory scientist: by bypassing the complex frequency analysis of the cochlea and directly stimulating the auditory nerve, they allow us to separate aspects of temporal and spectral (tonotopic) processing by higher centers of the auditory system. In a series of recent experiments, we have exploited this feature of cochlear implants to better understand the processing of complex signals by the auditory system. In this presentation, I will review these and other experiments on loudness, masking, and temporal processing in electrically stimulated hearing. Although Joe has not (as yet) worked on cochlear implants, his approach to sensory systems is undoubtedly the strongest scientific influence (the ‘‘Zwislocki effect’’) in my work in this area.
Time-reversal using ambient noise as a probe source
Authors: Roux Philippe , Song Hee Chun , Kuperman W. A.
Published: October 2013

The Green’s function between receivers in the ocean can be obtained from the temporal cross correlation of ambient noise measured simultaneously at those receivers [Ph. Roux, S. Lynch, W. A. Kuperman, and the NPAL Group, J. Acoust. Soc. Am. 112, 2421 (2002)]. Constructing the Green’s function similarly between a point receiver and an (source/receive) array from ambient noise creates, in effect, a surrogate probe source that provides data on a time reversal mirror. We show with theory and simulation that this noise-based time-reversal procedure results in a focus at the surrogate probe source. Finally, data are used to illustrate the feasibility of this process.
Derivation of moving-coil loudspeaker parameters using acoustical testing techniques: Theoretical developments
Authors: Leishman Timothy W. , Anderson Brian E.
Published: October 2013

Moving-coil loudspeaker driver parameters are generally derived through the measurement of electrical impedances. Nevertheless, because these drivers are electro-mechano-acoustical transducers, their parameters may also be determined from measurements taken in other physical domains. This paper presents theoretical concepts that show how they may be determined acoustically using plane wave tube techniques. A driver is mounted in a baffle to form a composite partition between a source tube and a receiving tube. The frequency-dependent transmission loss of the partition is determined using upstream and downstream sound field decompositions that compensate for possible nonanechoic receiving tube conditions. A transmission loss curve based on an equivalent circuit model of the system is then fit to the measured curve to extract specific driver parameters. Different electrical conditions are imposed at the driver terminals to modify the transmission loss in ways that allow the determination of additional parameters.
A feasibility study of air-coupled ultrasonic vibrometers
Authors: Petculescu Andi , Sabatier James
Published: October 2013

Several key issues arising when an ultrasonic field is used to probe small surface vibrations are presented. Sum and difference frequencies (sidebands) can be produced by the Doppler shift of the primary probe frequency incurred at the vibrating boundary and by the nonlinear parametric interaction with the radiation from the oscillating surface. Carrier and surface vibration amplitudes, the condition of the oscillating surface, and ambient parameters, influence the received signal. Wind critically affects the reliable operation of air-coupled acoustic sensors. As wind energy increases, the sensor detects a progressively richer turbulent spectrum that drowns the information-bearing sidebands. Experimental data of the scattering of ultrasonic energy by a turbulent environment is shown, aimed at searching for ways to actively recover the vibration sidebands. [Work supported by ONR.]
Acoustical imaging of spheres above a reflecting surface
Authors: Chambers David , Berryman James
Published: October 2013

An analytical study using the MUSIC method of subspace imaging is presented for the case of spheres above a reflecting boundary. The field scattered from the spheres and the reflecting boundary is calculated analytically, neglecting interactions between spheres. The singular value decomposition of the response matrix is calculated and the singular vectors divided into signal and noise subspaces. Images showing the estimated sphere locations are obtained by backpropagating the noise vectors using either the free space Green’s function or the Green’s function that incorporates reflections from the boundary. We show that the latter Green’s function improves imaging performance after applying a normalization that compensates for the interference between direct and reflected fields. We also show that the best images are attained in some cases when the number of singular vectors in the signal subspace exceeds the number of spheres. This is consistent with previous analysis showing multiple eigenvalues of the time reversal operator for spherical scatterers [Chambers and Gautesen, J. Acoust. Soc. Am. 109 (2001)]. [Work performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.]
The measurements of the compressional wave velocity of soils during unconsolidated-undrained triaxial testing
Authors: Lu Zhiqu , Hickey C. J. , Sabatier J. M.
Published: October 2013

In this study, a conventional triaxial cell was modified to measure the compressional wave velocity during a triaxial test. Two air-dry remolded soils taken from the counties in Sharkey and Neshoba, MS, were chosen for the study. Unconsolidated-undrained triaxial tests with pore pressure measurement were carried out. Soil samples were isotropically consolidated up to three different cell pressures, axially compressed with the axial strain up to 22%, and subjected to the unload–reload stress path cycles before and after soil failures. The velocity of the compressional wave in the axial direction as a function of the axial strain was measured along with the measurement of the stress–strain response. A comparison of the load-deformation behavior with the load-acoustic velocity behavior was made. The variation of the acoustic velocity with the effective stresses during the isotropic loading, normally consolidated compression and unload–reload stress path cycles were examined. Several empirical expressions of the compressional wave velocity in terms of the effective stresses and the over-consolidation ratio were proposed and examined with the measured data.
Automatic assessment of vowel space area
Authors: Sandoval Steven , Berisha Visar , Utianski Rene L. , Liss Julie M. , Spanias Andreas
Published: October 2013

Vowel space area (VSA) is an attractive metric for the study of speech production deficits and reductions in intelligibility, in addition to the traditional study of vowel distinctiveness. Traditional VSA estimates are not currently sufficiently sensitive to map to production deficits. The present report describes an automated algorithm using healthy, connected speech rather than single syllables and estimates the entire vowel working space rather than corner vowels. Analyses reveal a strong correlation between the traditional VSA and automated estimates. When the two methods diverge, the automated method seems to provide a more accurate area since it accounts for all vowels.
Voice segregation by difference in fundamental frequency: Effect of masker type
Authors: Deroche Mickael L. D. , Culling John F.
Published: October 2013

Speech reception thresholds were measured for a voice against two different maskers: Either two concurrent voices with the same fundamental frequency (F0) or a harmonic complex with the same long-term excitation pattern and broadband temporal envelope as the masking sentences (speech-modulated buzz). All sources had steady F0s. A difference in F0 of 2 or 8 semitones provided a 5-dB benefit for buzz maskers, whereas it provided a 3- and 8-dB benefit, respectively, for masking sentences. Whether intelligibility of a voice increases abruptly with small ΔF0s or gradually toward larger ΔF0s seems to depend on the nature of the masker.
Hader bar and clip attachment retained mandibular complete denture
Authors: Singh Kunwarjeet , Gupta Nidhi , Kapoor Vikram , Gupta Ridhimaa
Published: October 2013

Bar and clip attachments significantly improve the level of satisfaction of denture-wearing patients by enhancing the retention and stability of the prosthesis. These attachments have been most commonly used for connecting the prosthesis to implants, but they can be effectively used to retain tooth-supported prosthesis as well. The primary functions of bar attachments are splinting the abutments together, even distribution of forces to the abutments and supporting areas, guiding the prosthesis into place, improving the retention, stability, support and comfort of the patient. The primary requirement for the use of bar attachments is the availability of sufficient vertical and buccolingual space for the proper placement of the bar, sleeves, teeth arrangement and sufficient thickness of acrylic denture base to minimise incidence of denture fracture in the area of bar assembly.
Ischaemia-reperfusion injury in central retinal artery occlusion
Authors: Saxena Sandeep , Mishra Nibha , Meyer Carsten H , Akduman Levent
Published: October 2013

A 53-year-old man presented with sudden painless diminution of vision in his right eye for 3 days. His fundus examination showed diffuse whitening of the retina with a cherry red spot at the fovea with cilioretinal artery sparing. On fluorescein angiography delayed arteriovenous transit was observed. Three-dimensional spectral domain optical coherence tomography was used to assess retinal nerve fibre layer thickness and average macular central subfield thickness on days 3, 7, 30 and 90. Marked retinal oedema due to ischaemia was observed on day 3 of occurrence of central retinal artery occlusion. On day 7, significant decrease in retinal nerve fibre thickness and macular thickness was noted suggestive of acute reperfusion injury. Retinal nerve fibre layer thickness and macular thickness returned to near normal on day 30 due to restoration of blood supply with wash out of stress mediators. Retinal atrophy was observed on day 90.
VIBRATION ANALYSES OF CRACKED PLATES BY THE RITZ METHOD WITH MOVING LEAST-SQUARES INTERPOLATION FUNCTIONS
Authors: HUANG C. S. , CHAN C. W.
Published: October 2013

The solutions for the vibrations of cracked thin plates are obtained by the Ritz method with admissible functions. Based on the classical plate theory, the basis functions comprising polynomials and crack functions are adopted to generate the admissible functions by the moving least-squares approach for a set of nodes randomly distributed in the domain. The crack functions account for the singular behaviors of stress resultants at crack tip(s), which are discontinuous in displacement and slope across the crack. The present solutions are validated through convergence tests of frequencies and by comparison with the published results for simply-supported cracked rectangular plates. The solutions are further employed to determine the natural frequencies of cantilevered skewed rhombic and isosceles triangular plates and completely free circular plates, each with a crack of varying length, location and orientation. The numerical results are tabulated and some corresponding mode shapes are also presented, by means of nodal patterns. Most of the results shown here are new to the literature.
DNA STRUCTURAL FEATURES AND ARCHITECTURE OF PROMOTER REGIONS PLAY A ROLE IN GENE RESPONSIVENESS OF S. cerevisiae
Authors: YELLA VENKATA RAJESH , BANSAL MANJU
Published: October 2013

Gene expression is the most fundamental biological process, which is essential for phenotypic variation. It is regulated by various external (environment and evolution) and internal (genetic) factors. The level of gene expression depends on promoter architecture, along with other external factors. Presence of sequence motifs, such as transcription factor binding sites (TFBSs) and TATA-box, or DNA methylation in vertebrates has been implicated in the regulation of expression of some genes in eukaryotes, but a large number of genes lack these sequences. On the other hand, several experimental and computational studies have shown that promoter sequences possess some special structural properties, such as low stability, less bendability, low nucleosome occupancy, and more curvature, which are prevalent across all organisms. These structural features may play role in transcription initiation and regulation of gene expression. We have studied the relationship between the structural features of promoter DNA, promoter directionality and gene expression variability in S. cerevisiae. This relationship has been analyzed for seven different measures of gene expression variability, along with two different regulatory effect measures. We find that a few of the variability measures of gene expression are linked to DNA structural properties, nucleosome occupancy, TATA-box presence, and bidirectionality of promoter regions. Interestingly, gene responsiveness is most intimately correlated with DNA structural features and promoter architecture.
THE PURITY MEASURE FOR GENOMIC REGIONS LEADS TO HORIZONTALLY TRANSFERRED GENES
Authors: TANIGUCHI YUTA , YAMADA YASUHIRO , MARUYAMA OSAMU , KUHARA SATORU , IKEDA DAISUKE
Published: October 2013

Sequence analysis is important to understand a genome, and a number of approaches such as sequence alignments and hidden Markov models have been employed. In the field of text mining, the purity measure is developed to detect unusual regions of a string without any domain knowledge. It is reported in that work that only RNAs and transposons are shown to have high purity values. In this work, the purity values of regions of various bacterial genome sequences are computed, and those regions are analyzed extensively. It is found that mobile elements and phages as well as RNAs and transposons have high purity values. It is interesting that they are all classified into a group of horizontally transferred genes. This means that the purity measure is useful to predict horizontally transferred genes.
COMPARING VIRUS CLASSIFICATION USING GENOMIC MATERIALS ACCORDING TO DIFFERENT TAXONOMIC LEVELS
Authors: WANG JING-DOO
Published: October 2013

In this paper, three genomic materials — DNA sequences, protein sequences, and regions (domains) are used to compare methods of virus classification. Virus classes (categories) are divided by various taxonomic level of virus into three datasets for 6 order, 42 family, and 33 genera. To increase the robustness and comparability of experimental results of virus classification, the classes are selected that contain at least 10 instances, and meanwhile each instance contains at least one region name. Experimental results show that the approach using region names achieved the best accuracies — reaching 99.9%, 97.3%, and 99.0% for 6 orders, 42 families, and 33 genera, respectively. This paper not only involves exhaustive experiments that compare virus classifications using different genomic materials, but also proposes a novel approach to biological classification based on molecular biology instead of traditional morphology.