bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic cilia arrays using electrochemically-synthesized Galfenol nanowires and heterostructures.
Authors: Reddy Madhukar , McGary Patrick D. , Maqableh Mazin , Downey Patrick , Flatau Alison , Stadler Bethanie J. H.
Published: October 2009

A novel cilia design is introduced that incorporates a newly discovered magnetostrictive family of Fe–Ga alloys, also called Galfenol, into self-assembled, vertical nanopores to fabricate nanocantilevers. The mechanical response of the cilia to stimuli can be detected without direct contact by detecting their magnetic output via giant magnetoresistive sensors, similar to hard drive heads which can also be grown in nanoarrays. The electrochemistry of alloys involving non-ideal metals is very complex, so finite element modeling was used to simulate growth parameters and successful growth was achieved. A variety of nanowire geometries were produced, including segmented Galfenol with alternating nonmagnetic material to overcome the shape anisotropy of the nanowires. In addition, the mechanical properties of this new material were measured to determine the effects of nanostructuring. Finally, the nanowires were actuated using an external field to show their potential actuators as well as sensors. [Work supported by ONR.]
Multiphysics modeling of laminated Galfenol transduction devices.
Authors: Porter Scott P. , Thompson Stephen C. , Meyer Richard J.
Published: October 2009

Galfenol is an attractive giant magnetostrictive material for transducer design because of its competitive strain capabilities, mechanical robustness, and high magnetic permeability. The latter two properties are particularly interesting as they allow exploration of a design space inaccessible to other active materials, both giant magnetostrictive and piezoelectric. Especially noteworthy is the ability to roll Galfenol into thin sheets from which laminated assemblies may be economically produced. Lamination is an effective mitigation scheme against eddy current losses and in this paper the authors explore transducers based on this construction. Much of this work builds on the designs of World War II era magnetostrictive transducers developed at the Harvard Underwater Sound Laboratory. Modeling these transducers as electro-magneto-mechano-acoustical devices can be first achieved in a limited sense with a one-dimensional model; this model is valuable for rapid simulation during the early design process. Many of the physical phenomena present in the transducer, however, are inherently beyond the limitations of the one-dimensional model. For this reason, the authors have turned to a multiphysics approach for a comprehensive transducer simulation. In this modeling environment, the coupled differential equations describing the transduction are implemented in a three-dimensional finite element analysis.
Progress of noise control in Chile–South America.
Authors: Rooke Christopher H.
Published: October 2009

The Chilean experience can be interesting to other countries in Latin America. A short review from an educational point of view will include: Universities offering undergraduate acoustic programs and post graduate programs in Chile; non state institutions providing acoustic quality standards; short review of national standards and laws related to noise control in Chile: environmental noise law, hearing protection law, new laws, and standards at project stage at state institutions. Difficulties found on law application and challenges of state inspectors and institutions. How law implementation, undergraduate programs, community and business community awareness, and several factors had allowed a development of acoustic consultants, solution manufacturers, and installers and several other progresses. What is still missing and the long-term way to achieve higher levels of education—related to noise pollution and control—more effective laws and standards, state inspection, political will, consultant development, tested products and solutions, and general awareness of noise as a health problem where all of us had something to say and do to achieve better quality of life.
Noise reduction of honeycomb sandwich panels with acoustic mesh caps.
Authors: Naify Christina , Nutt Steve
Published: October 2009

The noise reduction effectiveness of acoustic mesh septa caps in composite honeycomb sandwich panels was evaluated. The acoustic mesh in the cells acted as a lightweight resonator in weight-critical aerospace structures. Nylon mesh was inserted into the honeycomb cells of the sandwich panels, and the acoustic absorption (AA) and transmission loss (TL) of the panels were measured using a normal incidence impedance tube. Single septa inserted into each cell yielded consistent improvements of 2 dB in TL over low- to mid-frequencies (50–1600 Hz). A double layer of septa further increased these acoustic properties in the mid-frequency range by an additional 2 dB. Varying the size of the mesh-weave had a significant effect. AA of the panels improved by a factor of 2 for the single septa and was further increased by perforating the panel facesheet. Results of the facesheet perforation were consistent with predicted values. Over low- to mid-frequencies, septa yielded measurable sound-mitigating results for a small weight addition with no change to the mechanical performance of the panels.
Vibration damping of metal foam-polymer interpenetrating phase composite.
Authors: Rayess Nassif E.
Published: October 2009

The damping and basic dynamic properties for a novel type of multifunctional hybrid material known as metal foam-polymer composite are investigated. This material is obtained by injection molding a thermoplastic polymer through an open cell aluminum foam, in essence creating two contiguous morphologies, an aluminum foam interconnected “skeleton” with the open pores filled with a similarly interconnected polymer substructure. This coexistence of both materials allows each to contribute its salient properties (e.g., the plastics contributing surface toughness and the metal foams contributing thermal stability). Basic damping testing results are presented for various aluminum foam porosities and pore sizes as well as for three types of polymers. A basic mathematical model of the damping is also presented. The integrity of the interface between the aluminum foam and the polymer is discussed in terms of its effect on the overall material damping.
Spatial and temporal properties of water column dynamics in the East China Sea.
Authors: Smith Chad , Kingsland Michelle , Bradley David
Published: October 2009

In late August, early September of 2008, 36 continuous hours of data from a conductivity, temperature, and depth chain tow were collected. The sensor chain spanned the lower portion of the upper mixed layer, a sharp thermocline, and the upper part of the isothermal lower water depth. The sound velocity field, calculated using the Chen–Millero formulation, is the result of a combination of events, including internal waves and density neutral intrusions. The features of the sound field are examined in terms of time variability and (oceanic) wave number behavior. Together with an accompanying paper that discusses sound propagation for these conditions, a detailed description of the impact of water column dynamics in a littoral coastal shelf is presented. [Acknowlegment of work supported by the Office of Naval Research, Contract No. N00014-08-1-0455.]
Time-frequency test signal synthesis for acoustic measurements during music concerts.
Authors: Ren Gang , Bocko Mark F. , Headlam Dave
Published: October 2009

When occupied by an audience, a musical performance space exhibits different acoustic characteristics compared to when it is empty. To obtain acoustical measurements with an audience present would require them to sit through an entire session of acoustic test signals, which is not practical. The dynamics of room acoustics parameters during an on-going concert may also be important to the mixing and recording engineers. These acoustic measurement scenarios demand an analysis tool for performing the designated tests during music concert sessions while not being noticeable by the audience. An acoustic measurement technique employing test signals generated during a musical performance is proposed. This method employs an adaptive time-frequency synthesis algorithm that determines the energy vacancies in the spectrogram of the on-going performance and automatically generates low-energy test signals that fill in the vacancies. The energy level of the test signal can be low enough to be masked by the music while high enough to be measurable above the noise floor. Several classes of test signals are proposed and their implementations in live musical events are demonstrated. Different system identification methods for estimating architectural acoustics parameters from the recorded test signals are also discussed and compared.
Investigation of the just noticeable difference of the clarity index for music, C80.
Authors: Ahearn Meghan J. , Schaeffler Matthew J. , Celmer Robert D. , Vigeant Michelle C.
Published: October 2009

The just noticeable difference (JND) of the clarity index for music, C80, has been reported to be approximately 1 dB, but there is limited research to support this value. A subjective study was conducted to verify this JND using a total of 51 musically trained subjects. Test signals were created using digital delays, equalizers, and reverberation-units, and sent out to eight loudspeakers distributed throughout an anechoic chamber. Three motifs and two C80 base-cases were tested: (1) had a C80 of −1 dB (1 kHz) with a 2.1-s reverberation time (RT), while (2) had a C80 of +3 dB (1 kHz) with a 1.6-s RT. Signals were presented in pairs with the first signal being the base-case and the second having a positive difference ranging between 0.5 and 3.0 dB. Control cases with no C80 differences were also presented. Results from all 51 subjects did not reveal a clear relationship between the percentages who heard a difference versus the difference in decibels. However, when the data were filtered to include 17 of the subjects, clearer trends resulted that suggest a higher JND of approximately 1.6 dB. Implications for future research will be discussed. [Work supported by the Paul S. Veneklasen Research Foundation.]
Multiple scattering through clouds of gas bubbles in liquids: Accounting for clustering in the higher-order moments.
Authors: Weber Thomas C. , Lyons Anthony P. , Bradley David L.
Published: October 2009

The presence of bubble clouds can change the sound speed and attenuation in liquids, both of which are often treated as first moment quantities that can be derived using a multiple scattering approach for an effective medium. The same multiple scattering framework can be used to examine higher-order statistical moments, accounting for the large variability that is often observed in acoustic signals in the presence of bubble clouds. When clustering of bubbles (preferred concentrations) is present, multiple scattering theory shows that the statistical moments should change. These cluster-induced, frequency dependent changes in sound speed, attenuation, and higher-order moments can be examined both from a theoretical standpoint and with the aid of numerical simulations. Simulations have shown that while point measurements of the acoustic field for non-clustered bubble clouds appear normally distributed, clustering introduces both a non-zero skewness and a higher than expected kurtosis, depending on the number density of the bubble clouds and the nature of the clustering. This type of behavior is expected to be present both for forward scattering and backscattering scenarios.
Structural transitions in self-healing materials utilizing resonant ultrasound spectroscopy.
Authors: Ricci Austin , Pestka Kenneth A. , Kalista Stephen J.
Published: October 2009

Poly(ethylene-co-methacrylic acid) copolymers are among a unique class of materials that can self-heal after exposure to extreme environmental stimulus, such as impact from a bullet. Recent experiments on these copolymers indicate that two distinct time scales govern the evolution of the healing process: a melt state, immediately after the damage, and a slowly evolving polymer interdiffusion. A unique approach will be presented for characterizing the time-scale of the interdiffusion state via observation of the system’s resonant spectrum.
Elastic moduli of single crystal palladium hydride near the tri-critical point.
Authors: Gladden Joseph R.
Published: October 2009

Palladium has long been studied as a model metal hydride system because of the high absorption rates and levels of hydrogen. Even moderately high pressures and temperatures can result in almost one to one hydrogen to palladium atom ratios. Depending on the ambient temperature and hydrogen pressure, the structural phase of hydrogen atoms in the palladium lattice can have three different forms: alpha, beta, and a mixed phase (alpha + beta). There exists a triple point in the pressure versus temperature phase diagram near 290° C and 400 psi. A recent model for absorption/desorption hysteresis in metal hydride systems predicts a sharp drop in the shear modulus near this triple point. Results from recent elastic constants and acoustic attenuation measurements as a function of both temperature and pressure near the triple point will be shown [R. B. Schwarz and A. G. Khachaturyan, Acta Mater. 54, 313 (2006)]. The experimental procedures for resonant ultrasound spectroscopy measurements at high temperatures and pressures will be also discussed.
Acoustic parameter estimates and confidence intervals for gravel at low frequencies.
Authors: White Michael J. , Swenson George W. , Borrowman Todd A. , Gertner George Z.
Published: October 2009

Rigid grain materials such as gravel offer the possibility of achieving low impedances and moderate attenuation for low-frequency acoustic waves. Using a standing wave impedance tube, we have estimated acoustic properties (wavelength, absorption coefficient, acoustic resistance, and reactance) for bulk compressional waves within and above gravel layers of several depths. In this paper we develop confidence intervals for the parameter estimates obtained by fitting measured data to a plane wave model using complex Fourier pressures. Comparisons to the three microphone method and microstructural impedance models are also made.
Acoustic wave transmission loss mechanisms in poroelastic media, modeling, and experiment.
Authors: Tavossi Hasson M.
Published: October 2009

Among factors that determine acoustic wave transmission loss in poroelastic media are incident wave energy loss due to acoustic impedance mismatch, between pore fluid and solid frame, and their density ratio, in addition to frequency dependence of dissipation in viscous boundary layers of fluid-solid interface for compression and surface waves. Model for prediction of transmission loss mechanisms includes the use of dimensionless Prandtl and Strouhal numbers for momentum and heat transfers, respectively. Other mechanisms considered are transmission losses by resonant and wave localization in the pore spaces. Wave filtering by poroelastic media as well as transmission loss by mode conversion, scattering, diffraction, interference, absorption, and thermal conduction are considered. Mechanical and electrical models of low-pass, band-pass, and high-pass filters applied to poroelastic media lead to the type of parameters to be included in this model as a function of frequency and pore size. Experimental measurements to test the prediction on acoustic wave transmission loss in similar poroelastic media of constant uniform porosity, but of different thicknesses and pore sizes, are presented to test transmission loss as a function of pore size, media thickness, and acoustic wave frequency.
Perceptual adaptation to a spoken passage’s long term spectral average.
Authors: Huang Jingyuan , Holt Lori , Lotto Andrew
Published: October 2009

The current study demonstrates that listeners adapt to a passage of speech such that subsequent speech categorizations are made relative to the passage’s long-term average spectrum (LTAS). Native-English participants listened to a passage from Harry Potter for about 2 min. Next, they completed a categorization task across a series of natural speech tokens from the same talker, manipulated to vary perceptually from /ga/ to /da/. The passage was filtered to emphasize or de-emphasize regions of the LTAS without altering perceived talker identity or intelligibility. Following exposure to a passage with greater high-frequency energy, listeners more often categorized targets as /ga/ compared to target categorization following the same passage with lower high-frequency energy. Thus, listeners exhibit sensitivity to long-term spectral distributions and categorize subsequent speech relative to the LTAS of the exposure context. The spectrally contrastive directionality of the effect is consistent with earlier work demonstrating the influence of adjacent context on speech categorization, but this study extends the findings to the LTAS of a passage (across minutes) and demonstrates that context need not be adjacent to influence speech categorization. The implications for this work for talker and accent normalization will be discussed. [Work supported by NIH R01DC004674].
Children need coherence masking protection.
Authors: Tarr Eric W. , Nittrouer Susan
Published: October 2009

Listeners can recognize speech targets at poorer signal-to-noise levels when more signal components are present, even if the additional components are spectrally distant and contribute no new information, but only if all components can be grouped together. [P. C. Gordon, Percept. Psychophys. 59, 232–242 (1997)]. This phenomenon (coherence masking release) was studied in adults and children using the first formant (F1) of [ε] and [ɪ] as targets. Formants were presented in low-pass white noise for vowel labeling, with and without a consistent F2/F3 component above the noise cutoff. Synthetic-speech and sine-wave stimuli were used. Thresholds for accurate labeling were obtained with an adaptive procedure for F1-only and for all 3-formants. For synthetic speech, adults had 3.3 dB of masking release for 3-formants compared to F1-only. Children showed a 6.5-dB effect in the same direction, due to higher thresholds for F1-only. All listeners heard sine waves as non-speech, showed similar thresholds, and had reduced masking release (1.5 dB), but in this case F1-only had the advantage over the 3-formant condition. Conclusions were as follows: (1) children need coherent signals to recognize speech in noise and (2) when combined with Gordon’s results, it seems masking release for speech signals likely has a phonetic explanation.
Gaze distribution patterns for audiovisual speech stimuli in preschool children with and without hearing loss.
Authors: Smith Nicholas A. , VanDam Mark , Moeller Mary Pat
Published: October 2009

Visual information plays an important role in the perception of speech. Many studies have shown that the addition of visual information increases speech intelligibility, and that the visual channel alone (as in the case of speechreading) is capable of conveying meaning. The goal of this study was to examine whether children with hearing loss use visual information in speech perception differently from children with normal hearing. An eye-tracking system (faceLAB) was used to record the looking behavior of 3- to 5-year-old listeners while they watched video samples of speech. Children with hearing loss used a variety of assistive devices, including cochlear implants and hearing aids. A group of normal-hearing peers was also tested. Preliminary results reveal that children with hearing loss distribute their gaze fixations more narrowly around the talker’s mouth region, whereas children with normal hearing scan the talker’s face more broadly. These differences may reflect hearing-impaired children’s ability to compensate for degraded auditory signals through increased reliance on visual cues.
Looking for phoneme-level inhibition in spoken word recognition using auditory lexical decision.
Authors: White James
Published: October 2009

The TRACE model of spoken word recognition [McClelland & Elman (1986)] contains phoneme-level inhibition while the MERGE model [Norris et al. (2000)] does not include active competition between phonemes. Previous work found evidence for facilitation at the phoneme level and competition at the lexical level, but little research has been conducted looking for the existence of inhibition between phonemes. Using an auditory lexical decision task, the current study looks for phoneme-level inhibition by giving participants English target words preceded by isolated English sounds as primes. There are three conditions depending on how related the prime sound is to the final phoneme of the target word: identical (e.g., [s] before “gas”), similar (e.g., [s] before “cash”), and unrelated (e.g., [m] before gas). Facilitation, or faster average reaction times (RTs), is expected in the identical condition relative to the baseline unrelated condition. If facilitation is also found in the similar condition, the results will provide evidence against phoneme-level inhibition, supporting an approach with gradient activation of phonemes. However, if the average RT for the similar condition is greater than or equal to that of the unrelated condition, the results will support models of spoken word recognition containing phoneme-level inhibition.
Modeling intensity fluctuations of acoustic transmissions from the Research Vessel Sharp during Shallow Water 2006.
Authors: Dossot Georges A. , Miller James H. , Potty Gopu R. , Badiey Mohsen , Lynch James F. , Lin Ying-Tsong , Newhall Arthur E. , Smith Kevin B.
Published: October 2009

During the Shallow Water 2006 (SW06) experiment, a J-15 source deployed from the University of Delaware’s R/V Sharp transmitted various acoustic signals at several different bearings and ranges to the Woods Hole Oceanographic Institution’s vertical hydrophone line array. The array was intentionally positioned near the shelf-break front and in an area where internal waves are known to occur. During several of the R/V Sharp’s acoustic transmissions, internal waves passed through the sound field such that the internal wave front was near parallel to the acoustic transmission path. Measured data show substantial intensity fluctuations that vary over time and space due to complex multimode and multipath (both two and three dimensional) interference patterns. This presentation provides an overview of the R/V Sharp’s transmissions and the corresponding intensity fluctuations of received signals at the array. In order to model the intensity fluctuations, a sound speed field is reconstructed using data from environmental sensors such as acoustic Doppler current profilers, ship radar, conductivity-temperature-depth profiles, environmental moorings, and satellite images. Measured data are compared to a simulated sound field computed by a three dimensional acoustic propagation model. [Work sponsored by the Office of Naval Research.]
In situ acoustic measurements of transmission loss for improving the effectiveness of antisubmarine warfare sonar searches in tactical scenarios.
Authors: Wiseman Charles H.
Published: October 2009

The execution of sonar search plans against submarines by antisubmarine warfare ships is not as effective as it could be, especially in littoral waters. The reason is that the high spatial and temporal variability of the water environment cannot be accurately characterized as inputs into models leading to the sonar equation, used for the prediction of sonar detection ranges, the primary input into search plans. The effectiveness of search can be significantly improved, however, by adding the use of in situ acoustic measurements of transmission loss to the mix of measurements currently used by tactical forces. This paper foresees improvements in the accuracy in use of the sonar equation, despite the likely incompleteness of in situ acoustic measurements of transmission loss relative to the entire field that would be desired to be measured. Acoustic measurements of transmission loss will bring into consideration a degree of ground truth into search that has not been realized tactically heretofore. The more effective search will translate to a closer to optimum use of navy ships, aircraft, and submarines, and a saving of fuel and search time. Accordingly, this concept should be analyzed and modeled to determine if it is worth investigating more thoroughly.
Full-field acoustic transmission variabilities including horizontal refraction and back-scattering effects in the shelf and shelfbreak environments.
Authors: Xu Jinshan , Lermusiaux Pierre F. J.
Published: October 2009

This study is motivated by the striking difference in acoustic transmission data collected on the shelf and shelfbreak northeast of Taiwan within the QPE 2008 Experiment. On the shelf, the acoustic transmission from a moving source along a circular track showed little variation with respect to bearing angles. However, on the shelfbreak, the data for the same type of circular tracks showed no transmission when the source was in the deeper waters. Our previous studies have investigated the uncertainties in transmission loss (TL) estimation due to the geo-acoustic model, bathymetry, and ocean environment by comparisons of N×two-dimensional and forward scattering acoustic modeling to in situ acoustic data. Here, we present a novel coupled oceanographic(four-dimensional)-acoustic[three-dimensional(3-D)] field estimation with ocean data assimilation modeling. A 3-D wave propagation model based on a parabolic approximation is used to study horizontal refraction effects on the TL. A coupled-normal-mode wave propagation model is also applied to investigate back-scattering effects on the TL. Our model estimates including uncertainties are compared to observed data, and results are utilized to study and quantify the variability of the TL due to the regionally complex seabed topography and ocean water column (tides, fronts, and eddies). Our study illustrates when processes such as sound wave horizontal refraction and back-scattering should be accounted for in modern SONAR performance prediction systems.
A model for four-dimensional coastal internal waves with applications to acoustics.
Authors: Lynch James F. , Duda Timothy F. , Lin Ying-Tsong , Newhall Arthur E. , Lermusiaux Pierre F. J.
Published: October 2009

Acousticians need a fully four-dimensional (4-D) coastal oceanography model that can provide the soundspeed field down to the internal wave scale. While mesoscale ocean models exist, given the complexities of a full primitive equation (i.e., nonlinear), non-hydrostatic, fine-scale model including internal waves, it may be a decade or more before such a model is available from the mainstream oceanographic community. We pose the possibility of creating a usable approximate 4-D ocean model based on a combination of a powerful acoustics technique, the Weinberg–Burridge vertical modes and horizontal ray solution to the wave equation, and existing primitive-equation ocean models and two-dimensional nonlinear wave equations. In our technique, the local ocean internal wave modes are found, creating a horizontal index of refraction grid for internal-tide ray tracing from identified source points. Broadband internal waves are propagated along the trajectories using the KdV or other appropriate nonlinear wave equation, with internal-tide initialization and interpolation between trajectories. An ocean numerical model with good bathymetry provides the source distribution as well as buoyancy frequency profiles and current profiles, necessary inputs for the internal wave modes and propagation. The initial design for this model as well as examples of its usages for ocean acoustics are presented.
Determining of directivity index and effective aperture at the idealized model of directivity pattern of antenna with elliptical cross section of main lobe.
Authors: Milosic Zvonimir
Published: October 2009

In this paper a new universal procedure of calculating directivity index (directivity factor) and effective aperture dependent on the measured directivity pattern of antenna will be presented. The procedure derives from an idealized model of directivity pattern measured characteristics of a sonar antenna in accordance with the elliptical cross section perpendicular to acoustic axes of the main lattice of directivity pattern. My new, strong, and original condition for very low level of suppression of side lobes at the contemporary sonars (LoSoSMiZ condition <−50 dB), its meaning in directivity index and effective aperture on ranges at previous congresses, and its meaning in theory of reverberation are in accordance with this theory too. In accordance with the equations in this paper, the de-embedding of directivity indices and effective aperture of the receive antennas of sonar systems is simple, fast, reliable, accurate, and widely usable. Finally, the de-embedding of directivity index and effective aperture according to the conditions in this paper makes a better evaluation of given parameters possible: for buyers, in R&D, in academies, and on the operative levels.
Soundscape design applications for transportation noise.
Authors: Siebein Gary W. , Lilkendey Robert M. , Paek Hyun , Jones Chris
Published: October 2009

Three case studies are presented that demonstrate soundscape methods for assessing noise impacts and proposed mitigation strategies for train, traffic, and rail noise impacts. Comparisons among time average measures short term measurements of specific acoustic events are presented. One is a large housing project located adjacent to a major rail line. The soundscape methods allowed the designers to auralize the results of proposed noise mitigation strategies for clients to make informed decisions about the acoustical feasibility of developing the site. Second is a case study of aircraft noise impacts on a glass curtain wall luxury condominium project located in the flight path of a major urban airport. Soundscape methods were used to work with the developers to assess strategies for the reduction in aircraft noise into living units associated with the decision to enhance glazing systems for the project. Third is a case study of planning for noise mitigation of road traffic noise for future developments at the time of initial permitting for projects. A framework for long term planning strategies for controlling incremental noise impacts as they occur was developed for a growing medium size city adjoined by rural and agricultural land.
Soundscape realization through standard surround sound.
Authors: Case Alex U.
Published: October 2009

The need for both qualitative and quantitative analyses may be the key challenge separating soundscape efforts from traditional environmental noise practice. On-site soundscape tours and interviews are a proven but resource-intense method for soundscape study. A means to obtain a soundscape and reproduce it elsewhere for subsequent analysis could be an efficient way to collect data and increase survey sample size. Reproduction off-site also makes soundscape modifications and comparisons possible, facilitating the measurement, evaluation, design, and composition processes. Standards specifying the full record and reproduce systems and procedures may never be able to anticipate the vast range of soundscape qualities that are salient across any and all soundscapes, loud to soft, low to high, large to small, transient to steady-state, urban to wilderness. The more pressing need is a review of the merits and shortcomings of the many soundscape recording and reproduction techniques most likely to be employed, and one small contribution is offered here. Cinemas and home theaters, with a somewhat-standardized 5.1-channel surround sound reproduction capability, might serve as a useful playback venue. They are well-understood by recordists and acousticians and have been used to fabricate a range of soundscapes in film and music, sometimes with great success. This paper evaluates the feasibility of using the 5.1 surround sound format for soundscape design.
Squealing noise in light rail transport systems: Implications in noise mapping.
Authors: Habaskova Lucie , Carvalho Antonio P.
Published: October 2009

Squealing noise is generated by railway vehicles riding through curves having closed radius. It is a result of wheels sliding on the rail when they negotiate a curve. This kind of noise is very annoying for people living in the surrounding areas where this phenomenon occurs because it has a characteristic spectrum that is dominated by discrete frequency components. Usually, squeal noise is not correctly accounted in urban areas noise maps. This paper presents the results of field measurements of squealing noise in Porto (Portugal) where a new light-rail system is operating. The goal was to characterize the acoustic effect of this type of noise in making noise maps. With the results obtained from in situ measurements, the squealing noise was simulated using CADNAA software. This paper compares three variants of squeal noise use and simulation with the software CADNAA. Comparing the noise map generated using the field measurements, with maps taking no account for squealing noise, a large difference in noise levels can be found (up to 17 dBA). A correction method was found to be incorporated in this model to improve the noise map estimation procedure.
Estimation of the contact pressure on the medial surface of the vocal folds during phonation.
Authors: Chen Li-Jen , Mongeau Luc
Published: October 2009

Voice production involves flow-induced self-oscillations of the vocal folds. Collision between the vocal folds is commonly observed during normal phonation. The contact pressure experienced by human vocal folds during collision is usually considered as the most likely source of phonotrauma. The goal of the present study was to quantify contact pressures in human subjects during phonation. A pressure sensor was developed for direct measurements. Verification data and preliminary data on human subjects were obtained. Subject response and other clinical challenges lead to the development of a less intrusive approach for the contact pressure estimation from high speed images based on a Hertzian impact model. A verification of the accuracy of this approach was made. Results from the nonintrusive approach were compared with results from direct measurements using a hemilaryngeal physical model of the human vocal folds. The experimental setup was designed to reduce sensor’s interference with the vocal fold oscillations. The accuracy of the estimated contact pressure from the nonintrusive method was found to be within around 10%. Advantages and possible sources of error are discussed. [Work supported by NIH.]
Prediction of the basilar membrane response to low-intensity acoustic stimulation using a mathematical model of the cochlea.
Authors: Meaud Julien , Grosh Karl
Published: October 2009

In the mammalian cochlea, the basilar membrane separates two fluid-filled ducts and vibrates in response to acoustic stimulation. In vivo measurements of a viable basilar membrane show that the membrane is very sensitive to low-level acoustic stimulation. A finite element model of the cochlea has been developed that explicitly couples the fluid, mechanical, and electrical domains of the cochlea. The proper function of the cochlea relies critically on structural acoustic coupling as well as electromechanical active control. The high sensitivity of the basilar membrane to low-intensity sounds is explained by the presence of somatic motility in outer hair cells. The outer hair cells convert electrical energy to mechanical energy, amplifying basilar membrane motion. Recent experiments show that the tips of the outer hair cells, the hair bundle, can also produce an active force at acoustic frequencies. Active force production by the hair bundle is included in the model to predict the effects of hair bundle motility on the basilar membrane vibrations. Our model allows us to answer important questions about the interplay of the various active forces in the cochlea; questions that are difficult to address by experiments alone.
Perception of non-native voicing contrasts by Buenos Aires Spanish listeners.
Authors: Rohena-Madrazo Marcos
Published: October 2009

Studies on cross-language speech perception have found that adults have difficulty discriminating segments that are non-contrastive in their native language; however, not all non-native contrasts are equally difficult to perceive. This study investigates whether Buenos Aires Spanish (BAS) listeners can perceive non-native voicing contrasts. Spanish has a phonemic distinction between voiceless stops /ptk/ and voiced stops /bdg/; however, it lacks a voicing contrast in fricatives, exhibiting only voiceless ones: /fsx/. BAS also has a palato-alveolar fricative, which is variably realized [∫-ȝ] depending on social factors, but this difference is not phonemic. To determine whether BAS listeners, possessing a native stop voicing contrast, can perceive the non-native fricative voicing contrast, they performed a categorial AX discrimination task, with Portuguese voicing pairs (p/b, t/d, k/g, f/v, s/z,;∫/ȝ). The results show that, unsurprisingly, listeners perceive the voicing distinction of stops at ceiling level. However, they are at chance distinguishing the fricative voicing contrast, with one exception: f/v. Listeners are equally accurate distinguishing the f/v contrast as they are with the stop contrasts and equally inaccurate distinguishing s/z,∫/ȝ. This suggests that the non-native f/v contrast has a different perceptual assimilation pattern than do the other non-native fricative voicing contrasts, s/z and ∫/ȝ.
Perception of prominence by Japanese and American listeners.
Authors: Shport Irina A. , Guion Susan G.
Published: October 2009

Acoustic cues to prosodic prominence are different in Japanese (mainly F0) and English (duration, F0, and intensity), but F0 change is involved in coding prominence in both languages. Japanese native speakers perceive a syllable as prominent (accented) if there is a sharp F0 fall originating in the syllable [Vance, (1987); Pierrehumbert & Beckman, (1988); Kubozono, (1993)]. It is not clear, however, whether native speakers of English interpret the F0 fall as a cue to prominence. In this study, participants are asked to identify a prominent syllable in each of the three-syllable words varying in (a) the location of the F0 maximum (the midpoint of the first or second syllable), (b) the height of the F0 maximum (10-Hz step increments from 200 to 250 Hz), and (c) the degree of the F0 fall between the accented and the following syllables (two levels). All stimuli are nonce words phonologically plausible in both Japanese and English. In our analysis we explore the role of each of the three manipulated parameters for perception of prominence by listeners who speak Tokyo Japanese and American English natively.
Language and dialect discrimination by five-month-olds.
Authors: Sundara Megha , Vicenik Chad
Published: October 2009

To acquire a language, infants must be able to accurately discriminate speech utterances belonging to that language. This is particularly important for infants raised in bilingual environments, who must be able to tag utterances they hear as belonging to one language or another. From birth, infants are able to discriminate languages from different rhythm classes, but not languages within the same rhythm class [Nazzi et al. (1998)]. By 5 months, infants can discriminate two languages from the same rhythm class, as long as one language is native. Johnson [(2000)] showed that English-learning infants could discriminate English from Dutch, and even American English from British English, but not Dutch from German. We attempt to extend these results to American English and German, and American and Australian English. Preliminary results show that English-learning 5-month-olds cannot discriminate American English from German but are able to discriminate American from Australian English. These results fit with previous work with adults that show discriminating between American and Australian English is easier than discriminating between American English and German, when segmental information is removed.
Marginal probability distributions for seabed parameter values from simultaneous processing of vertical and horizontal apertures.
Authors: Knobles D. P. , Koch R. A. , Sagers J. D.
Published: October 2009

Information about the physical parameter values for the seabed in a littoral region can be extracted from acoustic measurements in the water column. While acoustic data from both horizontal line arrays (HLAs) and vertical line arrays (VLAs) have been processed successfully to infer seabed properties, the simultaneous signal processing of acoustic data recorded on both a vertical and a horizontal aperture for seabed properties is a new research area. Relative to only a bottom-mounted horizontal aperture, an L-array (bottom mounted HLA and a VLA) provides access to the sensitivity of the depth-dependence of the acoustic field to seabed parameters. However, the utility of the additional information can be negated by uncertainty in the assumed water sound speed profile. Acoustic data collected on two L-arrays deployed on the New Jersey continental shelf are examined for the additional information about the seabed that can be obtained relative to the case for a single aperture. The information from simultaneous and individual processing of the subapertures is quantified in terms of the marginal distributions and an entropy functional approach. [Work supported by Office of Naval Research Code 321 OA.]
Seabed reflection measurements from an autonomous undersea vehicle: Probing seabed spatial variability.
Authors: Holland Charles W. , Nielsen Peter L.
Published: October 2009

Spatial variability of the seabed in littoral regions is driven by processes that span a large range of space and time scales, ranging from eustatic fluctuations which are more or less global in extent but can have a profound effect on sedimentary layering from hundreds of meters to sub-meter scales, to biologic reworking which might be very local and affect only the upper few tens of centimeters. These processes (as well as many others) conspire to create a rich variety of sediment property distributions both in vertical and horizontal dimensions. One way to probe the spatial variability is with wide-angle reflection measurements. Here we discuss results from the Clutter09 experiment in which seabed reflection measurements were conducted using a broadband source (800–3500 Hz) and a 32 element towed horizontal receiver. The results are compared with previous observations using a single hydrophone and a Uniboomer. [Work supported by the Office of Naval Research OA321 and the NATO Undersea Research Centre.]
Low-frequency propagation in extremely shallow water.
Authors: Costley R. Daniel , Muir Thomas G.
Published: October 2009

In water depths on the order of a wavelength, sound propagates with considerable involvement of the bottom, whose bulk and shear moduli as well as velocities and attenuation vary with depth into the sediment. This problem has been studied with a two dimensional finite-element code to illustrate the consequences of computational assumptions pertinent to these parameters and their gradients with depth into the sediment. Both time harmonic (steady state) and transient (animated pulse) sequences are treated in two dimensional depictions. [Work supported by the U.S. Army Space and Missile Defense Command.]
On the use of an autonomous underwater vehicle for seabed characterization.
Authors: Nielsen P. L. , Holland C. W. , Hollett R.
Published: October 2009

In 2009 NURC conducted the CLUTTER’09 experiment on the Malta Plateau, south of Sicily, in collaboration with the CLUTTER JRP partners from USA and Canada. One of the main objectives of this experiment was to characterize the seabed for geoacoustic and scattering properties related to clutter, i.e., around regions on the bottom which generate target-like returns on active sonar displays. The equipment used was a newly developed sound source and 32-m horizontal line array at NURC towed behind the Ocean Explorer Autonomous Underwater Vehicle (OEX-AUV). The source transmitted signals in the frequency band 800–3500 Hz and were received on the line array. The array has a four-level aperture which allows both for utilizing individual hydrophone data and beamformed data for the seabed characterization. The advantage of using the OEX-AUV is that measurements can be performed close to the seabed which are difficult to obtain from conventional sonar systems towed from a surface vessel. Results of environmental characterization using the OEX-AUV from a selected region are presented and compared to independent findings from previous experiments. [Work supported by the NATO Undersea Research Centre and the Office of Naval Research OA321]
Genotype Analysis Identifies the Cause of the “Royal Disease”
Authors: Rogaev Evgeny I. , Grigorenko Anastasia P. , Faskhutdinova Gulnaz , Kittler Ellen L. W. , Moliaka Yuri K.
Published: October 2009

DNA from historical specimens reveals the mutation causing the hemophilia that afflicted the royal families of Europe.
Reinstrumentation of an earthfill dam
Authors: Hanna A. , Lum K. Y. , Lou J. K.
Published: October 2009

The performance of the original instrumentation system of the Hugh Keenleyside Dam on the Columbia River in British Columbia was assessed after 25 years of operation. Many of the piezometers installed to monitor the performance of the dam and upstream blanket had failed. The adequacy of the remaining instruments was evaluated and the requirements for additional instrumentation were defined to reestablish "base conditions" for dam and blanket monitoring. A study of the existing piezometric data combined with the results of a comprehensive seepage analyses resulted in the development of an areal model simulating actual seepage conditions. The model was then employed to define the requirements and configurations of an upgraded instrumentation system that would be capable of detecting potential deficiencies in the till core and the upstream blanket. The instrumentation system was then upgraded to monitor the present flow regime. System upgrading requirements, implementation, and performance are described. Key words : instrumentation, earthfill dam, impervious blanket, flow regime, piezometers, upgrading, areal flow net, finite element, monitoring system.
Stress–strain response of Cold Lake oil sands
Authors: Wong R. C. K. , Barr W. E. , Kry P. R.
Published: October 2009

The stress–strain response of Cold Lake oil sands at confining stresses and temperatures up to 18 MPa and 200 °C, respectively, was studied in a triaxial apparatus using 89-mm full diameter cores. Tests that have been performed include conventional triaxial tests such as hydrostatic compression, initial Young's modulus determination, and cyclic drained and undrained compression. Tests involving pore-pressure increase and decrease under constant total stresses were also performed to simulate the stress path encountered in the field during the cyclic steam stimulation process. Treating oil sand as a particulate medium, possible modes of granular interaction were explored for all tests along different stress paths. Four modes of granular interaction were identified: (i) contact elastic deformation, (ii) rolling, (iii) shear dilation, and (iv) crushing. These modes provide a useful framework for explaining the behaviour arising from the effects of variation in void ratio owing to sample disturbance, stress level, stress path, induced anisotropy, and temperature. Other behaviour relating to critical state, localized shear deformation, and load–unload–reload are also examined. Key words : oil sand, stress, strain, void ratio, pore pressure, temperature, mode of granular interaction, critical state.