bluuebunny/crossref_metadata_2025 huggingface dataset:
Transmission and localization in connected ergodic reverberation rooms
Authors: Rozhkov Igor , Zelyak Oleksandr
Published: October 2013

The wave power redistribution in two connected reverberant structures represents a paradigm problem in studies of transmission through a complex structure consisting of several reverberant substructures. We analyze randomly coupled ergodic reverberation rooms with the goal to extend such analysis to a more general situation. The two-room problem is, however, quite challenging on its own [R. L. Weaver and O. I. Lobkis, J. Sound Vibr. 231, 1111–1134 (2000)]. Although the ergodicity assumption allows one to use random matrix theory (RMT), by describing both subsystems with random Gaussian Hamiltonians, the nonperturbative calculations of power transmission and localization have not yet been done. The only attempt made in this direction was the corresponding study of two coupled quantum dots [A. Tschersich and K. B. Efetov, Physi. Rev. E 62, 2042–2045 (2000)], which used the supersymmetry technique to calculate the joint distribution of local densities of electron wavefunctions and found spatial correlations absent in a single chaotic system. Here, we present both perturbative and nonperturbative (in ensemble averaging) RMT calculations of simplest nontrivial characteristics of power transmission and localization, and compare it with numerics.
The language interference of pitch accent language on tone language—A case study of Mandarin and Swedish
Authors: Tung Yi-Chen
Published: October 2013

The study aims to find how pitch accent language influences learning of tone language. The target language is Mandarin which has three contour lexical tones and one level lexical tone. The source language is Swedish which has two contour accents. It is assumed that Swedish cannot produce a Mandarin words with contour tone applied on single syllable since Swedish always exerts contour tone over two or more syllables. In experiment 1, it was found that the Swedish could produce a Mandarin contour tone completely. On the other hand, it was found that the Swedish subject used accent 1 to produce FR (falling+rising) and RL (rising+falling-rising) tonal combinations and accent 2 to produce RF (rising + falling) and LR (falling-rising+rising) tonal combinations. To further investigate the learning pattern of tone language, all the possible tonal combinations in Mandarin were tested in experiment 2. It was found that the Swedish subject applied accent 1 to produce all the tonal combinations. The result revealed that the language interference of pitch accent on tone language could be illustrated on the manipulation of direction of F0 movement.
Information-theoretic limits on spatial auditory display of sonar beam data
Authors: Summers Jason E. , Gaumond Charles F.
Published: October 2013

A signal-processing-based method that determines the number of independent channels in a set of head-related impulse responses (HRIRs) [B. Gardner and K. Martin, http://sound.media.mit.edu/KEMAR.html] is presented. The HRIRs in the horizontal plane are analyzed using information-theoretic methods and the resulting number of independent channels is shown as a function of noise level. These results are compared to previous psychophysical measurements of absolute and relative localization thresholds as a function of signal spectrum and target angle. This comparison leads to a noise level related to human perception. Additionally, the information-theoretic treatment is shown to yield a representation of the HRIR in the horizontal plane as a one-dimensional manifold in multidimensional coefficient space. An interpolation method is presented that is based on a distance measure on this manifold and is related to previous work [R. Duraiswami and V. C. Raykar, Proc. ICASSP 3, 285–288 (2005)]. Different distance measures are compared. Finally, these results are discussed in context of presenting beamformed sonar data via a spatial auditory display using a mapping of beams to sources in a virtual auditory space [G. R. Arrabito et al., Appl. Acoust. 66, 986–1005 (2005).] [Work supported by ONR.]
Modeling Doppler effects for acoustic communications
Authors: Siderius Martin , Porter Michael B. , Hursky Paul , McDonald Vincent
Published: October 2013

Performance of high-data-rate, bandwidth-efficient communications signals can be significantly degraded by failing to compensate for Doppler effects. Significant Doppler spread can be introduced simply from the sound interacting with the moving sea surface; however, the effects can be much greater when the source and receiver are also in motion. Numerical modeling that accurately accounts for Doppler effects can be used to develop and test communications algorithms. In this presentation, a simple technique will be presented for modeling communication signals in the ocean that includes Doppler effects. The challenge for modeling is due, in part, to the broad band and high frequencies (e.g., 3–50 kHz) typically used in underwater communications. The frequency band suggests using Gaussian beam tracing to determine the field. In addition, the Gaussian beams are conveniently interpolated and extrapolated to allow for the treatment of Doppler effects due to environmental and platform motion. The technique will be tested using simulations and experimental data from Doppler-sensitive transmissions.
Scattering by a set of sediment rough layers from a normal incident beam
Authors: Tang Dajun
Published: October 2013

The seabed can often be modeled as layers, which are in general not flat. The ability to model scattering from such rough layers is important for interpreting data from acoustics systems such as chirp sonar and echo sounders. The goal of this work is to investigate this scattering problem for a normal incidence scenario. A set of one-dimensional fluid rough interface realizations was generated using Monte Carlo method. Integral equations for the problem are solved, which include all multiple scattering effects. The solution is simplified when scattering matrices for each individual rough interface are pre-calculated. Based on the exact solution, the applicability of Kirchhoff approximation under various conditions is evaluated. The approximated method can then be applied to two-dimensional rough interfaces. [Work supported by ONR.]
Rethinking the library for the 21st century?
Authors: Nobile Peter
Published: October 2013

In the past few decades, the evolution of libraries has been increasingly dramatic and complex. Technology has fundamentally revolutionized information access, manipulation, and utilization. This transformation has challenged librarians and architects to evaluate the implications of these changes and their impact on the core mission of the library, its architecture, and the institution as a whole. Shepley Bulfinch is often engaged by our clients to help usher in the library for the 21st century. Such a facility is expected to fully integrate the digital and print worlds and introduce new spaces for media access, cyber cafs, 24/7 use, seminar and general instruction, faculty development labs, and GIS services. Additionally, such projects create flexible spaces that can be easily transformed to meet changing needs and uses. These projects bring with them significant acoustical isolation and technological access problems. However, such challenges are to be expected as these projects redefine the research and learning environment by integrating library resources, services, and users in spaces that reflect the overall evolution of the library.
Anthropogenic noise and baleen whales: A perspective from humpback whale acoustics
Authors: Au Whitlow W. L. , Lammers Marc O.
Published: October 2013

The effects of anthropogenic noise on baleen whales is a topic of intense interest not only to marine mammalogists but also to a variety of commercial interests, the military, oceanographers, and researchers that use sounds in the ocean. One of the major difficulties in setting standards for exposure levels and the effective use of anthropogenic sounds is a lack of knowledge of the auditory properties of whales. The auditory sensitivity and frequency range of hearing (audiogram) are not known, as well as how anthropogenic sounds physically affect the auditory system, the psychological well being, and the use of sounds by whales. One approach to gain some insight in this area is to study the acoustics of a baleen whale species, the humpback whale. The source levels and frequency range of humpback whale song units have been measured and can provide insights into what these whales expose each other to. The highest rms source level was 173 dB for a specific unit. The average sound pressure levels of chorusing have been measured and can provide insights into the long-term acoustic environment of humpback whales. The highest daily average of sound pressure level for chorusing sounds was 130 dB.
Sound production and detection by pinnipeds
Authors: Southall Brandon L. , Kastak David , Kastak Colleen Reichmuth , Insley Steven J. , Holt Marla M. , Mulsow Jason , Schusterman Ronald J.
Published: October 2013

Pinnipeds (seals, sea lions, and walruses) emit and receive sounds both in air and water. Their amphibious natural history has resulted in a number of fascinating sensory capabilities, including but not limited to hearing, but has apparently precluded the evolution of sophisticated biosonar systems. Pinnipeds produce vocalizations in a variety of social contexts, notably reproduction and aggression. Attraction calls in many species serve to retain or re-establish contact between females and offspring and to draw the attention of potential mates. Repulsion vocalizations warn adversaries and can advertise strength and intent. Cognitive processes, including conditioned learning, are an essential foundation of the sophisticated acoustic communication systems of pinnipeds. Recent advances in understanding these systems and passive listening in the context of predator and prey detection and spatial orientation will be discussed.
Linking sound production and dive behavior in feeding humpback whales
Authors: Stimpert Alison K. , Au Whitlow W. L. , Wiley David N. , Shorter Kenneth A. , Barton Kira L. , Johnson Mark P. , Ware Colin , Arsenault Roland
Published: October 2013

Acoustic studies of baleen whales are becoming increasingly common. However, a minority of studies combines acoustic data with technologies that allow sound production to be placed in a detailed behavioral context. Noninvasive digital acoustic recording tags (DTAGS) were attached to humpback whales (Megaptera novaeangliae) on the western North Atlantic’s Great South Channel feeding grounds to study foraging and acoustic behavior. Acoustic records totaling 48.4 data hours from four attachments were aurally and automatically analyzed, and occurrences of several sound types were correlated with body orientation and dive behavior of the tagged subject. Whales produced a wide variety of sound types, which differed in depth and context of production. Long, tonal groans and moans (3-s average duration, 500-Hz peak frequency) occurred more frequently in upper portions of the water column, in contrast to broadband paired bursts (50-ms average duration, 300-Hz peak frequency), which appeared associated with bottom feeding. Virtual behavioral study using GEOZUI4D is used to visualize how sounds may be associated with foraging behavior. Overall results indicate sophisticated, situation-dependent use of sound. Behavioral implications of masking effects by surrounding vessel traffic noise are discussed.
Wavelet-based denoising of manatee vocalizations
Authors: Niezrecki Christopher , Gur Berke M.
Published: October 2013

In the last decade, novel research on the wavelet transform has led to its recognition as a promising tool for denoising signals. Wavelet-coefficient-shrinkage-based denoising algorithms have been applied in various fields of science and engineering and successful results have been reported in Raman spectroscopy and medical imagery. Within this study, the wavelet transform is used to denoise manatee vocalization recordings corrupted with typical underwater noise such as boat, snapping shrimp, and water movement noise. The detection range and performance of acoustically based detection systems depends greatly on the SNR of the acoustic signal. A selective thresholding is performed on the wavelet coefficients and the denoised vocalizations are obtained through the reconstruction of these coefficients. The performance of the method presented is benchmarked against the well-known wavelet-coefficient-shrinkage-based denoising algorithms using the same underwater acoustic data obtained in prior studies. Preliminary results indicate that the suggested wavelet-transform-based denoising algorithm outperforms the shrinkage-based methods by an average of 5 dB.
A possible noncavitational mechanism of ultrasound-accelerated thrombolysis in fibrin clots
Authors: Everbach E. Carr , Chernysh Irina N. , Weisel John W.
Published: October 2013

Blood clots made of human plasma or purified fibrin with and without the addition of rt-PA were insonified with 1-MHz pulsed ultrasound on a microscope slide placed in a spectrophotometer. Clot dissolution times were measured by absorption of light at 350-nm wavelength passing through the clot. Dissolution times were halved for ultrasound-exposed clots versus shams. Clots with no rt-PA present showed a small but significant thrombolysis effect in the presence of ultrasound which could be prevented by the addition of factor XIII, which effectively binds the fibrin. Ultrasound pulse parameter variations showed a broad maximum effectiveness at 0.5-MPa peak negative pressure, 1-ms duration, and 50-Hz PRF. Concentration of protein in solution was elevated as much as a factor of 10 following insonification of clots without rt-PA, suggesting that ultrasound affects the kinetics of fibrin remodeling. A possible explanation that does not involve bubble activity is relative motion between the clot fibers and the interstitial fluid.
Cavitation-induced saturation of the negative-pressure phase of lithotripter shock pulses
Authors: Pishchalnikov Yuri A. , McAteer James A. , Bailey Michael R. , Sapozhnikov Oleg A. , Pishchalnikova Irina V. , Williams James C.
Published: October 2013

The tensile stress imposed by the negative-pressure phase of lithotripter shock pulses can cause cavitation. Bubbles continue to grow after the passage of the acoustic pulse; thus, some of the pulse energy is transformed to the kinetic and potential energy of the liquid surrounding the cavitation bubbles and, therefore, no longer belongs to the acoustic field. One might predict that this energy loss should be more pronounced for strong pulses that produce more cavitation. To investigate this, acoustic pulses were measured at the geometric focus of a Dornier HM-3 electrohydraulic lithotripter (water 39°C, dissolved gas ∼8% saturation) using a fiber-optic probe hydrophone FOPH-500. Measurements showed that, while the amplitude and duration of the leading positive-pressure phase increased dramatically as charging potential was increased from 12 to 24 kV, the trailing negative-pressure phase of the pulse remained unchanged. This stabilization of the negative-pressure phase could be due to cavitation restricting the amplitude of the negative pressure that can be transmitted through the liquid, such that further increase of the amplitude at the source would not increase the negative amplitude at the target but would only result in stronger cavitation along the acoustic path. [Work supported by NIH-DK43881.]
Mapping stone breakage to the acoustic field of the low-amplitude, broad-focal-zone lithotripter
Authors: Pishchalnikov Yuri A. , McAteer James A. , VonDerHaar R. Jason , Pishchalnikova Irina V. , Williams James C.
Published: October 2013

Recent reports describe the design, initial clinical experience, and mechanisms of stone breakage of a wide-focal-zone, low-pressure, self-focusing lithotripter [UMB 27, 638 (2001); 28, 769 (2002)]. We undertook mapping of the acoustic field of this device (Xixin lithotripter) using a fiber-optic hydrophone FOPH-500, and looked for correlation between features of the shock pulse, and breakage of gypsum stones at different locations within the field. The efficiency of stone breakage did not correlate with peak positive pressure, shock rise time, duration of the pulse, or positive area under the waveform, but did correlate with energy density and peak negative pressure. Breakage was significantly better at the target point of the imaging system and along the axis 20 mm proximal and distal to this point compared to the geometric focus, located ∼4 cm distally. Measured dimensions of focal width (∼15 mm) differed only slightly from the published value (18 mm), and stones up to 20 mm off-axis could be broken to completion although it took half as many pulses for breakage at 20 mm than at 15 mm. Thus, stone breakage was most efficient prefocally, and there appears to be considerable latitude for targeting with effective breakage both on-axis and lateral to the acoustic axis with this lithotripter. [Work supported by NIH-DK43881.]
Experimental investigation of linear resonant bubble behavior between parallel plates
Authors: Argo Theodore F. , Wilson Preston S.
Published: October 2013

Recent findings suggest that bubble clouds play an active role in the breakup of kidney stones in patients undergoing shock-wave lithotripsy treatment. Understanding the dynamic behavior of the bubble cloud and its component bubbles within confined spaces will increase the efficacy of the treatment, but to date, even idealized model systems are not well understood. The behavior of a single bubble near a rigid plane has been verified; the study of this configuration is one of a bubble and a single bubble image source. A model recently set forth [Cui et al., J. Acoust. Soc. Am. 119 (in press)] gives a description of the dynamics of a bubble between rigid parallel planes by using an infinite string of bubble image sources. This represents a step toward understanding the dynamics of fully enclosed bubble clouds. Experimental measurements of the resonance frequency and quality factor of air bubbles suspended between two parallel stainless-steel plates are presented and compared to the new model. An acoustic spectral subtraction technique was used to isolate the bubble response from that of the experimental tank. The bubbles were independently sized using diffuse backlighting and video microscopy. [Work supported by ARL:UT.]
Investigation of magnetostrictive materials and transducers for the generation of ultrasonic waves
Authors: Kropf Matthew M. , Tittmann B. R.
Published: October 2013

The magnetostrictive effect is commonly exploited to generate ultrasonic waves for many applications. A better understanding of the physical mechanism of magnetostriction in terms of material and transducer characteristics could expand its utilization to many new sensor applications. Maximizing the ustable frequency bandwidth for ultrasonic wave generation alone allows for various choices of modes that are individually suitable for different applications. Several different materials were analyzed and compared in terms of theoretically expected magnetostrictive efficiency. Frequency content of ultrasonic waves generated via magnetostriction was examined with reference to the geometry and configuration of a magnetic coil transducer. Static measurements were made and extended in an attempt to quantify magnetostriction in the dynamic sense. A survey of current applications and direction for future research is included.
An innovative piezoelectric force sensor to determine the integrity of electrical sockets
Authors: Blickley Elizabeth , Tittmann Bernhard
Published: October 2013

An ultrasonic force sensor was designed to calculate the socket contact force in a cable connector assembly. The force sensor operates through measuring the relationship between the mechanical force and change in resonance frequency in a piezoelectric tube. The sensor’s aim is to assess the effectiveness of aging electric sockets to ensure their replacement before failure. A network analyzer was used to perform tests on the repeatability and sensitivity of the resonance change in two sets of piezoelectric tubes of different thickness. The hoop mode proved to be the most consistent as well as most sensitive resonance mode. The results show an increase in the change in resonance frequency corresponding to an increase in applied socket contact force. Socket contact forces are measured through a friction-based method. To refine the testing technique, the 3-D modeling software SolidWorks was used to design a prototype socket testing device to hold the tubes for insertion into the socket. The piezoelectric tubes were adapted to perform in the tube holder and the prototype socket testing device was created out of aluminum.
Sonic demultiplexing by inverse designed scattering acoustical elements: An experimental demonstration
Authors: Sánchez-Dehesa José , Hȧkansson Andreas , Cervera Francisco
Published: October 2013

Experiments demonstrating sonic demultiplex devices able to spatially separate several wavelengths will be reported. The devices are based on clusters of cylindrical scatterers of circular section whose positions and sizes are determined by an inverse design approach. Two devices are reported, a first device that spatially separates two wavelengths, 20.0 and 22.7 cm, and a second that separates three wavelengths: 20.0, 21.3, and 22.7 cm. Both prototypes are typical examples of acoustic scattering elements, a name here introduced to define inverse designed devices characterized by their great adaptability in controlling the scattering image, including both the reflected and transmitted wave. [Work supported by MEC of Spain.]
Band-gap creation using quasiordered structures based on sonic crystals
Authors: Romero Garcia Vicent , Fuster Garcia Elies , Sanchez-Perez Juan V. , Garcia-Raffi Luis M. , Sanchez-Perez Enrique A.
Published: October 2013

It is well known that sonic crystals are periodic structures that present acoustic band-gap attenuation centered at frequencies related with the lattice constant of the structure. In this work we present a new approach based on genetic algorithms to create band gaps in a predetermined range of frequencies. The mechanism used by genetic algorithms to achieve this objective is the creation of vacancies in a starting sonic crystal, built with air-embedded rigid scatterers. As a result of the optimization process we obtain quasiordered structures whose acoustic properties are based in the multiple scattering theory. [This work has been supported by Universidad Politcnica de Valencia (Interdisciplinary Projects (P.I.I.Ref. 2003), Comision Interministerial de Ciencia y Tecnologia of Spain (Contract N. MAT 2003-04993-03), and by Generalitat Valenciana (Spain) under Grant GV04B-371.]
Cooling tower noise control
Authors: Paige Thomas S.
Published: October 2013

Cooling towers are typically provided with multiple large-diameter propeller fans mounted on top of the unit and discharging upward. These fans generate a significant level of low-frequency noise. The induced-draft intakes for these fans are typically located on the sides of the unit, so fan noise is also radiated horizontally from these openings. Traditional methods for noise control include sound-barrier walls, silencers, or complete noise enclosures. Barrier walls usually have no adverse effect on the performance of the cooling towers. However, silencers and close-fitting noise enclosures must be carefully designed to minimize resistance to the airflow that is required to maintain proper operation of the cooling tower. This paper discusses the current techniques used to reduce outdoor noise propagation from cooling towers. Some case studies are presented to illustrate successful implementation of these noise-control methods.
Numerical prediction of aerodynamic noise radiated from a cross-flow fan
Authors: Li Song , Chen Anbang , Huang Dongtao
Published: October 2013

The surface pressure fluctuations of blades, vortex wall, and the rear wall of a cross-flow fan are commonly considered as the aerodynamic noise sources of an air conditioning unit. In order to predict the noise, these pressure fluctuations were at first obtained by solving the 2D unsteady Reynolds-averaged Navier-Stokes (RANS) equations using a computational fluid dynamics software. It was validated by the fan performance experiments that the prediction of static pressure in the channel agreed well with the test data. It means the results of the pressure fluctuations obtained from the numerical simulation are correct. Then, the Ffowcs Williams-Hawkings (FW-H) equation was used to predict the far-field noise caused by these sources. The errors of the prediction of the sound-pressure levels of the blade passing frequency (BPF) and total noise are within 4 and 3 dB, respectively, comparing with the corresponding measured data. It is shown from the numerical prediction that only the surface pressure fluctuations of the rear wall and the vortex wall are main sources, and that the method of numerical prediction of aerodynamic noise radiated from a cross-flow fan is successful.
An analytical study of the effectiveness in noise control due to combination of mufflers in design of duct systems
Authors: Sridhara B. S. , Prasad M. G.
Published: October 2013

Mufflers are effective noise control devices used in acoustical design of duct systems. The performance evaluation of a single muffler in terms of four-pole matrix approach is well known. The performance evaluated in terms of four-pole parameters and insertion loss describes the system using various components namely source, muffler, and termination. The performance of a reactive muffler is known to be frequency dependent based on its internal geometrical details. This paper presents analytical studies on the effectiveness of combining mufflers on the noise control. The studies deal with both series and parallel arrangement of the reactive mufflers. The effects of various parameters such as number of mufflers, the length of ducts associated with the system, and the muffler geometry are presented. For a given source model, simple expansion chamber-type mufflers are studied in detail in order to understand the nature of interaction in different types of arrangements. Applications of this study would be to increase the noise reduction by combining mufflers in systems such as automotive, HVAC, etc.
Numerical prediction of vortex shedding noise radiated by a centrifugal impeller
Authors: Wang Weixiong , Huang Dongtao
Published: October 2013

Numerical prediction of fan noise is very difficult work because of the restriction of the computer technology. The fluctuating blade force caused by the vortex shedding from a centrifugal impeller is a main noise source but no paper has been published so far to predict this kind of noise. Vortex flow models to predict low-pressure axial flow fans were developed by several researchers since 1964. In this paper a study of numerical prediction of vortex shedding noise radiated by a commercial centrifugal impeller is reported, which is based on a vortex flow model developed by Lee in 1993. Three main research works are carried out by the authors. First, using FLUENT software a numerical simulation of 3D turbulent flow field of the impeller in order to predict the aerodynamic performance is completed and well validated by the experiment. Then, the velocity profile near the wall at the trailing edge of the blade is analyzed in detail to determine the boundary layer thickness both on the pressure and suction sides. Finally, the total SPL of the noise is predicted and the results agree with the experimental data within 3 dB near the design operation.
An ultrasonic analog for a laser
Authors: Weaver Richard , Lobkis Oleg , Yamilov Alexey
Published: October 2013

We report measurements on two simple ultrasonic systems analogous to random lasers. One system entails unstable ultrasonic feedback between distinct piezoelectric transducers on an irregularly shaped high-Q solid; another involves a spontaneously emitting piezoelectric device that can also emit by stimulation. Both are found to exhibit some of the behaviors of lasers. Over a wide range of parameters we observe narrow single-emission lines (natural width is estimated at about 0.0000000001 Hz), sensitivity to linear cavity properties, complex multimode emissions, and line narrowing.
Time-reversal acoustic focusing system based on the liquid-filled acoustic resonator
Authors: Sutin Alexander , Sinelnikov Yegor , Sarvazyan Armen
Published: October 2013

Numerous time-reversal acoustic focusing systems (TRA FS) based on the use of solid acoustic resonators (acoustic cavities) capable of accumulating acoustic energy in time are described in the literature. We experimentally demonstrated that the liquid-filled resonators can be superior to solid resonators in efficient focusing, especially in applications related to focusing of ultrasound in waterlike media, such as biological tissues. To understand the mechanisms of the observed effects and optimally design the water-filled resonators for biomedical applications, we developed a theoretical model and explored the factors defining the efficiency of TRA FS. The model allows evaluation of the spatial and temporal characteristics of TRA focused field formed as a result of numerous reflections of ultrasound within the resonator. The focused field structure and its dependence on the shape and size of the resonator, ultrasound frequency, and attenuation, and the coefficient of ultrasound reflection from the resonator walls were investigated. Principles of optimization of the resonator shape and size are developed. It is shown that for the resonator filled with an attenuating liquid TRA focusing in binary mode of radiation provides narrower focal spot than conventional analog signals. The experiments confirmed the predictions of developed theory.
Band gap engineering for two-dimensional periodic systems of fluids
Authors: Kushwaha Manvir S. , Djafari-Rouhani Bahram
Published: October 2013

Periodic binary systems can give rise to genuine acoustic stop bands within which sound and vibrations remain forbidden. Extensive band structures have been computed for two-dimensional (2D) periodic arrays of air cylinders in water background. Complete, multiple, huge stop bands are found for both square and triangular lattice arrangements. The lowest stop bands are largest for a range of filling fraction 10%≤f≤55%, with a gap/midgap ratio of 1.8. The most interesting finding of the present investigation is that the low-frequency, flat passbands for a perfectly periodic system correspond to the discrete modes of a single airy cylinder. This is attributed to the low-filling fraction and huge density contrast in air and water. It is stressed that such a simple inhomogeneous system as made up of air and water exhibits the largest stop bands ever repoprted for 2D and/or 3D phononic as well as photonic crystals.
History effects on the motion of particles subject to acoustic fields
Authors: Allen John S. , Coimbra Carlos F. M. , Kobayashi Marcelo H.
Published: October 2013

Acoustic fields have been used to trap, manipulate, and separate particles suspended in fluids. The separation of solid and gas particles is possible since the acoustic radiation force depends on the particle’s size, density, and compressibility. Moreover, numerous devices using acoustic standing waves have been developed for this purpose. The ability to model and accurately predict the particles’ trajectories and distributions resulting from these applied acoustic fields is of great importance for a wide range of biomedical and industrial applications. However, limited previous theoretical efforts have been made to account for the unsteady viscous effects on a particle’s motion in an acoustic field. We examine these unsteady history effects on a particle in the vicinity of a nodal point in an acoustic standing wave field. The relative importance of the history (Basset) force, which has a fractional derivative dependence of the order 3/2, is demonstrated for acoustic separation device conditions. The inclusion of the history force has the net effect of changing the eigenfunctions of the problem from exponential to Mittag-Leffler functions in time, thus influencing the overall acoustic force balance.
Possibilities of thin-film bulk acoustic resonators as punctual mass sensors
Authors: Campanella Humberto , Esteve Jaume , Montserrat Josep , Uranga Arantxa , Abadal Gabriel , Barniol Nuria , Romano Albert
Published: October 2013

In this work, thin-film bulk acoustic resonators (FBARs) are implemented as punctual mass sensors, with the purpose of future integration in biomolecular sensing systems, where selective spatial detection is required. The piezoelectric thin film is a (002)AlN membrane, sputtered over Ti/Pt on a (001)Si wafer, and released by surface micromachining of silicon. The effective lateral area of resonator is 50×50μm, and the thicknesses of AlN and Ti/Pt layers are 1000 and 180 nm, respectively. A punctual mass of a C/Pt/Ga composite with a contact surface much smaller compared to that of the resonator’s electrode is deposited on the top electrode of the resonators, by means of a focused ion beam. Selected areas of the electrode, especially near the center of the resonator, were chosen to growth the composite with lateral dimensions in the units of micrometers, and thickness on the order of several nanometers. Based on the mass-loading principle, the sensor changed its resonance frequency in a proportional manner to the added mass, achieving an average sensitivity of 2.4−22 g/Hz and a mass resolution an the order of femtograms. Regarding these results, FBAR is proposed as a candidate to measure localized particles and, in general, to be applied as biological mass sensor.
Spatial auditory attention
Authors: Shinn-Cunningham Barbara G.
Published: October 2013

Historically, most psychoacoustic studies measured performance on tasks limited by bottom-up, sensory factors. However, in the everyday world, sensory sensitivity does not always determine performance. The problem in many everyday settings is not that components of an important sound source cannot be heard, but rather that they are not noticed amidst the clutter caused by competing sound sources. In particular, recent evidence suggests that competition for central resources is often the primary limitation on performance in tasks in complex, uncertain environments. This talk will review results of recent studies demonstrating that spatial cues are one important feature that can enable a listener to focus attention on a sound source of interest and mediate competition for central resources. Psychophysical results will be interpreted in light of physiological measures from visual and auditory tasks illustrating the importance of top-down factors on neural activity. Parallels and differences in the role of spatial attention for visual and auditory tasks will be discussed. Speculations about these similarities and differences will be offered, driven by the hypothesis that similarities derive from common control circuitry, while differences arise from differences in peripheral neural coding. [Work supported by AFOSR, ONR, and NIDCD.]
Spatial cues are used differently for localizing and identifying the same attended auditory object
Authors: Lee Adrian K.C. , Deane-Pratt Ade , McAlpine David , Shinn-Cunningham Barbara
Published: October 2013

Spatial cues not only affect localization of auditory stimuli, they also influence the formation of perceptual objects (streams). Previous experi-ments demonstrate that spatial cues influence the grouping of an ambiguous target tone that logically could be part of two different objects in the auditory scene. For such ambiguous stimuli, spatial cues affect how the target tone is grouped, changing the perceived rhythm of a repeating tone stream and the perceived identity of a slowly repeating vowel [Lee et al., ‘‘The missing target: Evidence of tone’s inlability to contribute to the auditory foreground’’ Proc. Mid-Winter Meeting of the ARO, New Orleans (2005)]. Here, we investigate whether perceived location of tone and vowel streams can be predicted by the grouping results of these previous identification experiments. Results show that the perceived location of the attended object (the repeating tones or vowels) depends on (1) interactions between the perceived locations of the two objects comprising the stimuli and; (2) the spatial cues contained in the target tone. Moreover, the degree to which the target tone affects perceived object location is not predicted by the degree to which the target is perceived as part of the attended object. This suggests that spatial cues affect object formation and object location, but in ways that are independent of one another.
Consonant-vowel place linkages in the babbling of 6-, 9- and 12-month-old learners of French, English, and Mandarin
Authors: Giulivi Sara , Whalen D. H. , Goldstein Louis M. , Levitt Andrea G.
Published: October 2013

The place of articulation of consonants and vowels in CV syllables in babbling has been claimed to be linked, such that front vowels predominantly occur with labial consonants, mid-vowels with coronals, and back vowels with velars[P. F. MacNeilage, Behav. Brain Sci. 21, 499–546 (1998)]. Support for this claim has come from a variety of languages, but a further implication has not been tested: If children depend on this frame/content approach less as they develop, there should be a trend away from it as language mastery increases. Here, we examined the babbling of six English-learning, five French-learning, and five Mandarin-learning infants, sampled at 6, 9, and 12 months of age. There was only moderate support for the frame/content account in the overall ratios, with velars occurring noticeably less often than predicted with back vowels. Further, there was no pattern toward a decrease in evidence for frame/content organization across these 6 months. Together with other theoretical considerations, these results cast doubt on the utility of the frame/content account for language acquisition.
Effects of experience on speech perception in noise
Authors: Wayland Ratree , Li Bin , Csonka LaTosha , Harnsberger James
Published: October 2013

This study will report on an experiment designed to test the hypothesis that the benefit derived from naturally clear speech is commensurate with listeners’ increased exposure to the target language. Research participants were 37 native Chinese speakers, 15 native Spanish speakers, 16 native Thai speakers, and 30 native speakers of English served as control subjects. All participants were asked to listen to four lists of English sentences identical to those used in Bradlow and Bent (2002). These sentences were produced in a conversational and a clear speaking style by a male speaker. All sentences were then normalized for their rms amplitude and mixed with white noise to generate two sets of stimuli (for each speaking style) with a signal-to-noise ratio of −4 and −8 dB, respectively. The number of key words (N=50 for each of the four lists) correctly identified by each listener were obtained. The statistical analyses to be performed on the data will focus on comparing the performance of subjects, both within and across language group, whose experience with English differs significantly.
Temporal aspects of voicing in Russian and English
Authors: Zak Roza , Gelfer Carole
Published: October 2013

The study compares temporal aspects of voicing in Russian and English. Specifically, it examines whether Russian-English bilinguals who have learned English as a second language (L2) in early childhood are able to differentiate Russian and English consonants /p/, /b/, /t/, /d/, /k/, /g/ according to voice onset time (VOT). Monolingual Russian-speaking 3-year-old children’s VOTs will be compared to those of monolingual Russian-speaking adults. Bilingual (Russian and English) 9-year-old children’s VOTs will be compared to monolingual 9-year-old children’s VOTs. It is predicted that 9-year-old bilingual children will demonstrate appropriate voicing boundaries in English; however, their production of Russian VOTs will differ from the Russian monolingual production.
Return of the weckud wetch: Rapid adaptation to a new accent
Authors: Bardhan Neil P. , Aslin Richard N. , Tanenhaus Michael K.
Published: October 2013

This study investigated listeners’ adaptation to a new accent within a portion of the vowel space of their native language. Previous work has shown that such adaptation requires only brief exposure [Maye et al., ‘‘In search of the weckud wetch: Online adaptation to speaker accent,’’ CUNY Conference on Sentence Processing, Cambridge, MA (2003); Clarke & Garrett, ‘‘Rapid adaptation to foreign-accented English,’’ J. Acoust. Soc. Am. 116, 3647–3658 (2004)]. However, neither adaptation involved visual referents and the postadaptation assessment involved either a lexical decision task or a cross-modal lexical matching task. In the present study, English-speaking listeners were exposed to a list of lexical items in which front vowels were lowered (e.g., ‘‘witch’’ became ‘‘wetch’’) but back vowels were not (e.g., moon). During adaptation, subjects selected an object from a visual array after hearing a naturally produced, accented form of the object’s name. In a postadaptation lexical decision task subjects were more likely to accept the accented form as a word than before training. Also examined were the effects of generalization across the lexicon to untrained words and throughout the vowel space to include back vowels. This paradigm of lexical adaptation lends itself to further studies using an eye-tracking measure to assess dialect influences on lexical access in spoken word recognition. [Work was supported by NIH 5R01DC005071-05 and NIH 5T32DC000035-12.]
Perception and production of English vowels by native speakers of Mandarin
Authors: Lopez Karece , Yu Yan Helen , Bell-Berti Fredericka
Published: October 2013

This study examines the relationship between the identification of English vowels by 48 Mandarin ESL speakers and their production of these same vowels, and how factors of AoA, LoR, general and English education, and language spoken at work and home influence that relation. The Mandarin ESL speakers produced eight repetitions of the following words, heed, hid, head, had, hod, hawed, hood, who’d, hud, and heard, and then identified tokens of each of these words produced by two native speakers of Greater Metropolitan New York City English. Native speakers of American English identified the productions of the Mandarin ESL speakers to provide a measure of their ability to produce these vowels. We hypothesize that general and English educational background and language use influence the L2 English speakers’ perception and production of English vowels, and that the more accurately the L2 listener distinguishes a vowel contrast, the more distinctly he/she produces that contrast.
Pronunciation of English vowels of native Turkish speakers
Authors: Sadaka Janine , Ng Manwa
Published: October 2013

Foreign accent can be defined as the allophonic variations in the target language (L2) under the influence of the first language (L1). This is mainly caused by the incorrect placement of articulators during production of the vowels and consonants of L2. As direct acoustic correlates of articulatory gestures, formants can be a valuable tool to indicate the amount of misarticulation, and thus amount of accent traits. The present study attempts to investigate the amount of accent in Turkish-English bilingual individuals producing English vowels. The first two formant frequencies (F1 and F2) of eight English monophthongs produced by ten male and ten female native Turkish will be analyzed. The bilingual speakers have been using English and Turkish in their daily communication. All English vowels are produced three times in the /hVd/ context. Five data points will be selected evenly along each vowel segment, and the average F1 and F2 values will be measured. The average F1 and F2 values thus measured will be compared with those of native English speakers as reported by Peterson and Barney (1952). It is hypothesized that the F1 and F2 values of the accented English vowels will be slightly different from those produced by native English speakers.
Vowel errors and sentence intelligibility in Spanish-accented English speech
Authors: Dalby Jonathan
Published: October 2013

It has been shown that foreign-accented speech is more difficult for listeners to process than native speech when presented under noisy listening conditions. It has also been shown that errors in vowel productions are more damaging to connected speech intelligibility than are errors or distortions in consonant production. This study compared the intelligibility of Spanish-accented English vowels in isolated words with that of short samples of connected speech. Five native Spanish speakers who had learned English as adults read a list of 42 monosyllabic English words selected so that 14 Spanish-accented English monophthongs could be presented to native listeners in a three-alternative forced-choice identification task. In each trial the target and two nearby (in the vowel space) distracters were presented. Talkers also read a set of 20 phonetically balanced sentences. Ten native English listeners identified the vowels in the isolated word task and judged the intelligibility of the sentences in a simple write-down procedure. While overall sentence intelligibility scores are not very well predicted by word intelligibility scores when the full set of vowel contrasts is included, predictability improves when a subset of the vowels is chosen. [Work supported by Purdue Research Foundation.]
Measured and modeled multirank signals in a range-dependent environment
Authors: Heaney Kevin D.
Published: October 2013

Environmental variability can take the form of sound-speed fluctuations, range- and azimuthally dependent geoacoustics, and strong bathymetric gradients. In this paper we examine the rank of strong broadband tones in a strongly range-dependent environment and the subsequent effect on adaptive processing. Range-dependent transmissions off the coast of Kauai were recorded during the Basin Acoustic Seamount Scattering EXperiment (BASSEX04) in September of 2004. Broadband transmissions (27-s M-sequence, 75-Hz center frequency) of the North Pacific Acoustic Laboratory (NPAL) source-mounted bottom in 900 m of water off the coast of Kauai were recorded using a 200-m towed line array. The single-element signal-to-noise ratio (SNR) is on the order of 15 dB before matched filtering, so there are no issues of adequate SNR for adaptive beamforming. With such a strong single source, the spread in eigenvalues will be studied as an indication of the effect of motion, environmental variability, and multipath propagation. In this environment, the rank of the CSDM is significantly higher than can be modeled using 2D range-dependent parabolic equation modeling, indicating that environmental variability (scattering, 3D acoustics) dominates over motion and multipath effects (which are well handled in the PE modeling).