bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Airfoil Thickness on the Efficiency of Low-Pressure Turbines
Authors: Torre Diego , Vázquez Raúl , Armañanzas Leyre , Partida Fernando , García-Valdecasas Guillermo
Published: October 2013

The effect of airfoil thickness on the efficiency of low-pressure (LP) turbines has been investigated experimentally in a multistage turbine high-speed rig. The rig consists of three stages of a state of the art LP turbine. The stages are characterized by a very high hade angle, reverse cut-off design, very high lift, and very high aspect ratio airfoils. Two different sets of stators have been designed and tested. The first set of stators is made of airfoils with a thickness to chord ratio around 10% along the span with the exception of a small areas close to the end walls. In those areas, the thickness has been increased above the previous value to reduce the secondary flows. These types of airfoils have been referred to in the literature as “spoon” airfoils. The second set of stators has been designed to have the same spanwise distribution of pressure coefficient (Cp) on the suction surface than the first set. However, the thickness to chord ratio was increased along the span up to values around 20% to raise the velocity of the flow and to remove any separation bubble on the pressure side. The resulting shape of the profiles is representative of “hollow” airfoils. The velocity triangles, chord distribution, leading and trailing edge locations, and flowpath have been maintained between both sets. They have been tested with the same blades and at the same operating conditions with the intention of determining the impact of the profile thickness on the overall efficiency. The turbine characteristics: sensitivity to speed, specific work, Reynolds number, and purge flows have been obtained for both sets. The comparison of the results suggests that the efficiency of both types of airfoils exhibit the same behavior; no significant differences in the results can be distinguished.
Forcing of Separation Bubbles by Main Flow Unsteadiness or Pulsed Vortex Generating Jets—A Comparison
Authors: Lyko Christoph , Dähnert Jerrit , Peitsch Dieter
Published: October 2013

Low pressure turbines typically operate in the low Reynolds number regime. Depending on the loading of the blade, they may exhibit detached flow with associated reattachment in the rear part of the suction surface. Additionally, the flow is highly time-dependent due to the sequence of rotating and stationary blade rows. The work presented in this paper covers experimental efforts taken to investigate this type of flow in detail. Typical low pressure turbine flow conditions have been chosen as baseline for the experimental work. A pressure distribution has been created on a flat plate by means of a contoured upper wall in a low speed wind tunnel. The distribution matches the one of the Pak-B airfoil. Unsteadiness is then superimposed in two ways: A specific unsteadiness was created by using a rotating flap (RF) downstream of the test section. This results in almost sinusoidal periodic unsteady flow across the plate, simulating the interaction between stator and rotor of a turbine stage. Furthermore, pulsed blowing by vortex generating jets (VGJ) upstream of the suction peak was used to influence the transition process and development of the separation bubble. Measurements have been performed with hot-wire anemometry. Experimental results are presented to compare both forcing mechanisms. In sinusoidal unsteady main flow, the transition occurs naturally by the breakdown of the shear layer instability, which is affected by periodic changes in the overall Reynolds number and thus pressure gradient. In opposition, active flow control (AFC) by VGJ triggers the transition process by impulse and vorticity injection into the boundary layer, while maintaining a constant Reynolds number. The flow fields are compared using phase averaged data of velocity und turbulence intensity as well as boundary layer parameters, namely shape factor and momentum thickness Reynolds number. Finally, a model to describe the time mean intermittency distribution is refined to fit the data.
Emerging Technologies in Medicine.
Authors: Djajaputra David
Published: October 2013

Emerging Technologies in Medicine. Anastasio J., La Riviere P., Imaging in Medical Diagnosis and Therapy, edited by William R. Hendee CRC, Boca Raton, FL, 2013. Price: $169.95. ISBN: 978‐1‐4398‐8041‐8, 361 pp. (hardcover).
How does a magnetic trap work?
Authors: Pérez-Ríos J. , Sanz A. S.
Published: October 2013

Magnetic trapping is a cornerstone of modern ultracold physics and its applications, including quantum information processing, quantum metrology, quantum optics, and high-resolution spectroscopy. Here, a comprehensive analysis and discussion of the basic physics behind the most commonly used magnetic traps used in Bose-Einstein condensation is presented. This analysis includes the quadrupole trap, the time-averaged orbiting potential trap, and the Ioffe-Pritchard trap. The trapping conditions and efficiency of these devices can be determined from simple derivations based on classical electromagnetism, even though they operate on quantum objects.
Assessment of outdoor soundscapes in quiet areas
Authors: Nilsson Mats E. , Berglund Birgitta
Published: October 2013

Existing quiet outdoor areas should be preserved. Appropriate indicators and limit values are needed, which are grounded in knowledge on positive aspects of soundscapes, such as perceived pleasantness and psychological restoration. For this reason, a questionnaire study was conducted in four green areas close to a major city and in four city parks. Measured equivalent sound levels (LAeq, 15 min) ranged between 42 and 50 dBA in the green areas, and between 49 and 60 dBA in the city parks. Sounds from nature, such as bird song, completely dominated the soundscape in the green areas. The city-park soundscapes were more complex, containing sounds from nature, as well as technological sounds (e.g., traffic noise), and human sounds (e.g., human voices). In general, sounds from nature were perceived as pleasant, technical sounds as annoying, and human sounds as neutral. Between 84 and 100% of the visitors in the green areas assessed the soundscapes as good or very good. The corresponding percentages for the city parks were distinctly lower, between 52 and 65%. The results indicate that the equivalent sound level should be below 50 dBA in order to secure pleasant and restorative outdoor soundscapes in urban areas.
Implications of the road traffic and aircraft noise exposure and children’s cognition and health (RANCH) study results for classroom acoustics
Authors: Stansfeld Stephen A , Clark Charlotte ,   the RANCH Study Team
Published: October 2013

Studies in West London have found associations between aircraft noise exposure and childrens’ cognitive performance. This has culminated in the RANCH Study examining exposure-effect associations between aircraft and road traffic noise exposure and cognitive performance and health. The RANCH project, the largest cross-sectional study of noise and childrens health, examined 2844 children, 9–10 years old, from 89 schools around three major airports: in the Netherlands, Spain and the United Kingdom. Children were selected by external aircraft and road traffic noise exposure at school predicted from noise contour maps, modeling and on-site measurements. A substudy indicated high internal levels of noise within classrooms. Schools were matched for socioeconomic position within countries. Cognitive and health outcomes were measured by standardized tests and questionnaires administered in the classroom. A parental questionnaire collected information on socioeconomic position, parental education and ethnicity. Linear exposure-effect associations were found between chronic aircraft noise exposure and impairment of reading comprehension and recognition memory, maintained after adjustment for mothers education, socioeconomic factors, longstanding illness and classroom insulation. Road traffic noise exposure was linearly associated with episodic memory. The implications of these results for childrens’ learning environments will be discussed. [Work supported by European Community (QLRT-2000-00197) Vth framework program.]
Natural referent vowels guide the development of vowel perception
Authors: Polka Linda , Bohn Ocke-Schwen , Molnar Monika
Published: October 2013

Certain vowels are favored across languages of the world. This selection bias has received a great deal of attention in linguistic theories seeking to explain vowel system typologies. In comparison, the role that specific vowels might play in the ontogeny of vowel perception has been more implicit. In this talk we will summarize recent findings that elucidate the functional significance of peripheral vowels in the development of vowel perception. Data from cross-language studies of infant vowel discrimination and vowel preference will be presented. This work shows that peripheral vowels have a perceptual priority for young infants and that this bias is independent of the phonemic status of the vowels presented in the perceptual task. Findings from cross-language experiments with adults reveal that language experience builds on the natural vowel biases observed in infancy. Adult data suggest that the natural bias remains in place in mature listeners unless the perceiver needs to override the bias to optimize perception of functional vowel differences. These findings support our proposal of a Natural Reference Vowel hypothesis as a framework for understanding the development of vowel perception and production. Specific avenues of research needed to elaborate this framework will be outlined. [Work supported by NSERC.]
Sound-quality analysis of sewing machines
Authors: Chatterley James , Boone Andrew , Blotter Jonathan , Sommerfeldt Scott
Published: October 2013

Sound quality analysis procedure and results for six sewing machines ranging from entry level to professional grade will be presented. The procedure consisted of jury-based listening tests and quantification of sound quality using standard metrics. The procedures and analysis of the jury testing will be presented and discussed. The correlation between the quantitative metrics and the qualitative jury results will be presented. Sound localization scans, using near field acoustic holography techniques with accompanying results, performed in order to determine machine sound hot spots and possible sources for undesired sounds, will also be presented. Proposed modifications to machine structure in order to alter machine sound signature into a more sensory pleasant sound will also be presented.
Coarticulatory nasalization in modern Greek: Evidence for a link between coarticulation and syllable structure
Authors: Diakoumakou Evanthia
Published: October 2013

An acoustic analysis of the temporal extent of vowel nasalization in the productions of six native speakers of (Standard) Modern Greek showed that the temporal extent of anticipatory vowel nasalization is limited in all contexts, although it is more extensive before tautosyllabic than heterosyllabic nasals. (On average, in stressed syllables, heterosyllabic anticipatory nasalization was 27 ms long, tautosyllabic anticipatory was 48 ms long, and carryover was 70 ms.) Modern Greek patterns in this aspect with languages like Spanish, Italian, Ikalanga, which also show a tendency toward open syllables, and obstruents are, in general, dispreferred as codas. It is hypothesized that there may be a link between a tendency for open syllables in a language and limited extent of anticipatory nasalization and it is suggested that investigation of the prosodic organization of languages may prove fruitful in determining the factors that lead to cross-language coarticulatory differences regarding vowel nasalization.
Revisiting the Canadian English vowel space
Authors: Hagiwara Robert
Published: October 2013

In order to fill a need for experimental-acoustic baseline measurements of Canadian English vowels, a database is currently being constructed in Winnipeg, Manitoba. The database derives from multiple repetitions of fifteen English vowels (eleven standard monophthongs, syllabic /r/ and three standard diphthongs) in /hVd/ and /hVt/ contexts, as spoken by multiple speakers. Frequencies of the first four formants are taken from three timepoints in every vowel token (25, 50, and 75% of vowel duration). Preliminary results (from five men and five women) confirm some features characteristic of Canadian English, but call others into question. For instance the merger of low back vowels appears to be complete for these speakers, but the result is a lower-mid and probably rounded vowel rather than the low back unround vowel often described. With these data Canadian Raising can be quantified as an average 200 Hz or 1.5 Bark downward shift in the frequency of F1 before voiceless /t/. Analysis of the database will lead to a more accurate picture of the Canadian English vowel system, as well as provide a practical and up-to-date point of reference for further phonetic and sociophonetic comparisons.
An improvisation on the Middle-Eastern mijwiz; auditory roughness profiles and tension/release patterns
Authors: Vassilakis Pantelis N.
Published: October 2013

Within western musical tradition, auditory roughness constitutes one of the principle perceptual correlates of dissonance. A previous study [P. N. Vassilakis, Selected Reports in Ethnomusicology, Vol. 12 (in press)] addressed the musical significance of auditory roughness within western as well as three non-western musical traditions. It introduced a new roughness estimation model that predicts successfully roughness ratings of synthesized complex diatonic dyads. For the present study, an application was created that uses the aforementioned model to estimate the roughness of natural signals with arbitrary spectra, as well as roughness profiles of short musical pieces. The application was used to examine if and how the pattern of tension and release within a stylized improvisation on the Middle Eastern mijwiz (double clarinet) relates to roughness changes. Tension/release patterns were indicated by the Lebanese improviser and expert mijwiz player (Dr. A. J. Racy) and were also obtained by both musicians and non-musicians (American-raised) in a perceptual experiment. The results suggest that auditory roughness is a good predictor of the tension/release pattern indicated by the improviser. The patterns obtained by the subjects, although not very consistent, appear to be different overall, suggesting that musical tension and release may be culture-specific concepts.
Electronic noise suppression in the wavelet, frequency, and time domains
Authors: Arvelo Juan
Published: October 2013

Automatic machine gun recordings were severely contaminated with electronic noise. A detailed examination of the character of the electronic noise revealed that it consists of periodic pulses at an interval of about 4.2 ms and that its frequency content is rich in narrow-band lines with a colored broadband background. Given the impulsive nature of the electronic noise in the time domain, wavelet decomposition was applied in an attempt to harness the noise and to null it out. An alternative approach was also implemented where a bank of stop band Butterworth filters were applied in the frequency domain to suppress the narrow-band components of the electronic noise. Other approaches include the use of adaptive cancellation in the time and frequency domains. We will demonstrate and compare the performance of these approaches emphasizing the need to minimize their influence in distorting the signal of interest.
Autonomous signal separation microphone system based on the spatio-temporal gradient analysis
Authors: Teramoto Kenbu , Tsuruta Kosuke
Published: October 2013

This paper presents a novel autonomous directivity microphone system based on the newly proposed spatio-temporal blind source separation. Recently, the methods of blind source separation and multi-deconvolution of source signals have been proposed in various fields, especially, acoustic applications including the cocktail-party problem. The blind source separation principally uses no a priori knowledge about parameters of convolution, filtering and mixing. In the simplest case of the blind source separation problems, observed mixed signals are linear combinations of unknown mutually statistically independent, zero-mean source signals. The spatio-temporal blind signal separation algorithm utilizes the linearity among the four signals: (1) temporal gradient, (2) x; (3) y; and (4) z-directional spatial gradients of the sound-pressure, all of which are governed by the equation of advection. The proposed method, therefore, has an ability to simplify the convolution blind source separation problems into the instantaneous blind source separation over the spatio-temporal gradient space. The acoustical experiments are performed with the particle velocity microphone (Microflown) successfully instead of sound pressure microphones. Because, x; y; and z-directional gradients of the sound pressure are equivalent the temporal derivatives of the corresponding directional particle velocities theoretically.
Attenuation in the sediment layers in East China Sea
Authors: Potty Gopu R. , Miller James H.
Published: October 2013

Compressional wave attenuation in the frequency range 50 to 350 Hz is estimated using broadband data collected in the East China Sea. A time-frequency analysis provides amplitudes of individual modes which are used to estimate the modal attenuation coefficients. Different modes are sensitive to sediment properties at different depths and this mode-depth sensitivity is explored in a sensitivity study. Based on this sensitivity study attenuation in different layers of the sediments will be estimated using different modes which are sensitive at these depths. This is a variation of previous studies where different frequencies have been used to invert for different sediment parameters using sub-space approaches. This approach focuses the inversion to various layers (provided by the geophysical surveys at the site) of the sediment and hence presents a tool to describe the depth variations in the sediment. The attenuation versus frequency behavior of the different sediment layers will be discussed. [Work supported by ONR.]
Acoustic velocity measurements in seafloor sands at frequencies from 1 to 400 kHz
Authors: Zimmer Michael A. , Bibee L. Dale , Richardson Michael D.
Published: October 2013

We measured the acoustic velocity and attenuation at frequencies from 1 kHz to 400 kHz in shallow seafloor sands off Fort Walton Beach, FL, USA. We used three separate systems with overlapping frequency ranges in order to cover this entire frequency range. For frequencies from 1 to 20 kHz, we implanted a seafloor array of 35 hydrophones and 5 three-component accelerometers at depths from 0 to 1 m over a 4 m by 4 m area, and recorded signals from two acoustic sources positioned at offsets from 1 m to 20 m. Measurements from 15 to 120 kHz were made at 30-cm sediment depths with the In Situ Sediment Acoustic Measurement System (ISSAMS), which consists of a linear array of 4 piezoelectric probes; the outer probes transmit a single-frequency burst while the inner probes act as receivers. Additionally, velocity measurements were made on diver-collected cores (5–20 cm sediment depths) at frequencies from 50 to 400 kHz. We present comparisons of the measured frequency dependence of the acoustic velocity and attenuation to theoretical predictions from various constitutive and wave propagation models, parameterized with inputs from detailed characterizations of diver-collected cores.
Miniature self-contained acoustic recorders applied in a survey of beluga-whale populations in Knik Arm, Alaska
Authors: Burgess William C. , Williams Michael T. , Blackwell Susanna B.
Published: October 2013

Since 1995, acoustic recording tags attached to marine wildlife have increased our understanding of how animals use and respond to sound. Tagging studies require these instruments to be designed for minimum size and maximum recording capability; however, by designing for ease of use as well, a variety of other acoustic studies become feasible that could not otherwise be attempted for lack of time, staff, or support. As a result, designing for ease of use multiplies the scientific power of acoustic recording tag technology. In late 2004 four acoustic recording tags, known as Bioacoustic Probes and developed by Greeneridge with ONR support, were used as fixed recorders in a primarily visual survey of beluga whales in the Knik Arm of Cook Inlet, Alaska. The study took place with a compressed schedule and was staffed by field biologists with little time available for technical training on the use and maintenance of the instruments. Designing the instruments for ease-of-use enabled the study to include an independent acoustic component for assessing the presence or absence of beluga whales in areas that were being surveyed visually during daylight hours. [Work supported by Knik Arm Bridge and Toll Authority.]
Industrial noise control—Technical and economic feasibility
Authors: Roth Stephen I.
Published: October 2013

Industrial noise control is too often considered technically not possible or economically infeasible. The use of ear protection devices becomes the fallback approach to attempt to reduce the risk of worker hearing loss. In reality there are noise control opportunities in industrial settings than are low cost and provide significant noise reduction without affecting production and maintenance practices. This paper will present mechanical and pneumatic noise controls that can be successfully applied to industrial environments. This paper will also present information on OSHAs approach to determine whether engineering noise controls are considered economically feasible.
Sound attenuation by lattices of rigid elliptic cylinders
Authors: Torrent Daniel , Håkansson Andreas , Sánchez-Dehesa José
Published: October 2013

The attenuation properties of acoustic barriers consisting of a few layers of rods with elliptical cross section has been studied by multiple scattering theory. Their performance as a function of number of layers and orientation of the ellipses will be reported and compared with similar structures based on cylinders of circular section. A comparison with available experiments will also be presented. Finally, a genetic algorithm is applied to optimize the attenuation in a wide range of frequencies. [Work supported by MEC of Spain.]
Some medical applications of acoustic streaming
Authors: Crum Lawrence A.
Published: October 2013

Classical acoustic streaming results when an acoustic field is absorbed in a liquid, and the resulting momentum transfer causes the liquid to be translated. Acoustic microstreaming results when a bubble or other compressible entity is caused to oscillate by an acoustic field and hydrodynamic flow is induced in the vicinity of the oscillating surface. Much of the pioneering work on this general topic was performed by Wesley Nyborg and his students at the University of Vermont. There are a number of conditions for which acoustic streaming can be useful in medical ultrasound; e.g., one can enhance diffusion rates of drugs by inducing streaming at a specific site in tissue; together with Doppler imaging, one can determine the consistency of a particular sample of fluid, such as a blood clot. These and other examples of the use of streaming in medical ultrasound will be presented. [Work supported in part by the NIH and NSBRI.]
Evaluation of backscattered intensity to quantify the destruction rate of echogenic liposomes
Authors: Porter Tyrone M. , Vaidya Sampada S. , Holland Christy K. , Huang Shao-Ling , MacDonald Robert C. , McPherson David D.
Published: October 2013

Echogenic liposomes (ELIP) are vesicles with a phospholipid bilayer shell that can serve as ultrasound contrast agents (UCA) for diagnostic purposes and for targeted drug delivery. The efficacy of ELIP as an UCA depends upon its stability in an acoustic field, whereas the use of ELIP for drug delivery will require releasing the encapsulated drug rapidly at the desired treatment site. The objective of this study was to evaluate the rate of destruction of ELIP as a function of pressure and pulse repetition frequency (PRF). Assuming ELIP destruction is directly related to its echogenicity, transducers with center frequencies of 3.5, 7.5, and 10 MHz were used to acquire pulse-echo data from ELIP suspensions ([lipid]=0.2 mg/ml). The rate of ELIP destruction was defined by fitting an exponential decay function Ae−kt to the backscattered intensity data. The relationship between ELIP destruction and acoustic pressure and PRF was determined by comparing the decay time constant k across samples. Based on this analysis, the rate of ELIP destruction was found to be directly proportional to pressure and PRF for all frequencies tested.
Modeling pulse propagation in the nocturnal boundary layer
Authors: Waxler Roger , Gilbert Kenneth E. , Kulichkov Sergey , Talmadge Carrick
Published: October 2013

The propagation of broad band (0 to 1000 Hz) pulses in downward refracting atmospheres over lossy ground is modeled in the time domain by Fourier synthesis using a modal model for sound propagation in the frequency domain. Of particular interest is the dispersion of the pulse as it propagates. A conjecture of Chunchuzov, Bush, and Kulichkov [J. Acoust. Soc. Am. 88, 455–461 (1990)] that at long ranges such pulses have a universal form, is shown to be true. In general, at long ranges from the source, the pulse develops a narrow band tail, centered around 20 or 30 Hz. This tail is formed by the superposition of surface modes.
ArtiSynth designing a modular 3D articulatory speech synthesizer
Authors: Vogt Florian , Guenther Oliver , Hannam Allan , van den Doel Kees , Lloyd John , Vilhan Leah , Chander Rahul , Lam Justin , Wilson Charles , Tait Kalev , Derrick Donald , Wilson Ian , Jaeger Carol , Gick Bryan , Vatikiotis-Bateson Eric , Fels Sidney
Published: October 2013

ArtiSynth is a modular, component-based system for performing dynamic 3D simulations of the human vocal tract and face. It provides a test bed for research in areas such as speech synthesis, linguistics, medicine, and dentistry. ArtiSynths framework enables researchers to construct, refine, and exchange models of all parts of the vocal tract and surrounding structures. ArtiSynth introduces a probe concept to unify input and output data flow, which allows control of and access to models with time varying data series. ArtiSynth supports interconnected heterogeneous models, such as rigid body, mass-spring, and parametric, using a point-set connection method, called markers, for constraint satisfaction. Using ArtiSynth, we created a muscle-driven rigid body jaw model, a parametric principle component tongue model from MRI images, a parametric lip model, and mass-spring face tissue model. We combined them in various ways. Data from medical imaging (MRI, CT, and ultrasound) and other technologies such as optical tracking can be used to drive ArtiSynth models. We are currently developing an acoustical rendering framework supporting source-filter models and other advanced methods. The system incorporates a powerful scripting interface as well as an easy-to-use graphical interface. [Work supported by NSERC Canada and ATR Japan.]
An educational articulatory synthesizer, EASY
Authors: McGowan Richard S. , Wilhelms-Tricarico Reiner
Published: October 2013

An articulatory synthesizer has been written for general educational and research use. It has been named Educational Articulatory Synthesizer, EASY, and written in the MATLAB programming language. In its current instantiation, the synthesizer performs calculations in the frequency domain and includes the effects of wall-vibration, viscous and thermal boundary layer loss, and radiation loss. Sources anywhere from the glottis to the mouth can be specified. Further, the code allows for side branches other than the nasal tract so that sounds such as laterals can be specified. A low-frequency aerodynamic module has also been included. Midsagittal shape is controlled by a hierarchy of flesh points. Points high in the hierarchy specify the overall shape by determining reference positions for points lower in the hierarchy, which, in turn, determine the shape locally. [Work supported by grant NIDCD-001247 to CReSS LLC.]
Influence of random nonlinear internal wave parameters on resonant acoustic mode coupling
Authors: Frank Scott D. , Siegmann William L.
Published: October 2013

Shallow water transmissions sometimes suffer anomalous amplification or loss caused by mode coupling due to the presence of nonlinear internal wave packets. The possibility of coupling between two acoustic modes is specified by an internal wave-acoustic resonance condition, which relates acoustic wavenumber differences to peak locations of the packet spectrum. This mechanism is critical in a recent analysis [S. D. Frank et al., J. Acoust. Soc. Am. 116, 3404–3422 (2004)] of some broadband intensity variations from the SWARM 95 experiment. That investigation used regularly spaced, evenly-sized nonlinear internal wave packets and it is important to determine how random variations in the wave widths and inter-wave spacings affect propagation results. An analytic expression for the wavenumber spectrum of an idealized packet is obtained in terms of these parameters. This expression predicts spectral peak locations for parameters from the SWARM 95 model that correspond with observed data. Estimates of peak location statistics arising from random packet parameter variations are analyzed computationally and analytically. Variability of internal wave spectral peak locations is correlated with broadband intensity fluctuations obtained from parabolic equation computations. [Work partially supported by ONR.]
Community design with soundscape in mind
Authors: Brooks Bennett M.
Published: October 2013

Community standards for sound are usually defined by limits on noise emitters. These limits may be absolute in level, or relative to a background level. Most often a limit is given as an overall A-weighted level. Occasionally, limits are placed on octave band spectrum levels or on tonal content. The time function of noise is generally addressed only broadly, defined by terms such as impulse, intermittent, or continuous. The character of sound in the community is addressed in policy or law by vague definitions which prohibit sounds which are obnoxious or that cause a nuisance. The positive aspects of sound in communities are usually left to chance. Recently, one summer resort community initiated a policy which promotes outdoor entertainment in one district, while requiring quiet in another. This unique policy balances lifestyle and economic interests, and was developed through an inclusive community-based public process. The question of how the community-based policy development process may be used to enhance the soundscape of a targeted area is explored. The implications of such a policy process for the designers of buildings and public spaces are discussed.
Aesthetic transformations of soundscapes as a basis for architectural design
Authors: Siebein Gary
Published: October 2013

A graduate design studio in acoustics examines sound and silence as manifest in urban and rural exterior soundscapes as well as interior soundscapes within performance venues as potential theoretical and formal bases for architectural form. The soundscape analyses were composed of a series of quantitative and qualitative studies of real and virtual environments such as the actual project site in downtown Orlando and the interior soundscape of the Stats Opera in Vienna in the 19th century. Transformations of the soundscape analysis served as generative ideas for the basis of architectural interventions in complex sites and programs for a multi-venue performing arts center.
Occlusive thrombosis in the rabbit auricular vein in vivo targeted by induction of intralumenal cavitation using HIFU and ultrasound contrast agent
Authors: Brayman Andrew A. , Tu Juan , Matula Thomas , Crum Lawrence A. , Hwang Joo Ha , Kimmey Michael B.
Published: October 2013

Hypotheses tested: (1) inertial cavitation [IC] could be induced in the venous lumen in vivo by combined use of intravascular microbubble contrast agent and transcutaneous application of 1-MHz high intensity focused ultrasound [HIFU] of very low duty factor, and that IC activity could be detected and quantified in vivo as in earlier in vitro studies via passive cavitation detection methods; (2) robust IC activity would damage the venous endothelium in treated regions; (3) endothelial damage would be proportional to the IC dose developed in the region; (4) severe local endothelial damage alone may be sufficient to induce occlusive thrombosis, or may sensitize the region to low systemic doses of prothrombotic agents, and (5) biologically significant temperature rises and attendant thermal bioeffects in the vessel and perivascular tissues would not occur, even under the highest amplitude acoustic conditions applied. Each hypothesis was supported by the data. The principal result was that under treatment conditions involving very high peak negative acoustic pressures and contrast agent, treated areas thrombosed acutely but non-occlusively. When fibrinogen was administered locally after such treatment, occlusive thrombi formed acutely and only in the treated region, a response observed with none of the other treatments.
Local dynamical effects in inhomogeneous elastic waaveguides
Authors: Grinchenko Victor T.
Published: October 2013

The properties of normal waves in elastic waveguides are essentially different than properties of normal waves in acoustical waveguides. As the physical reason of the differences one can indicate the specific phenomena of reflection of elastic waves from a free surface. When an elastic wave reflects from the surface, the energy of longitudinal waves transforms to shear waves and vice versa. It is shown that the conversion of the wave motion types sets condition for generation of local disturbances in wave fields when normal waves are reflected from geometrical and physical inhomogeneities. The paper presents quantitative and qualitative analysis of the local effects for different cases. It was shown that such effects occur in a simple elastic waveguide. The specific features and physical meaning of the edge resonance effect in semi-infinite waveguides is presented. It was shown that for the waveguides with geometrical and physical inhomogeneous interesting phenomena of anomalous transparency of discontinuity can occur for any frequency bands. For other frequency bands the same discontinuity can be as an effective reflector of incident normal wave.
Simplified series expansions for radiation from a baffled circular piston
Authors: Mast T. Douglas , Yu Feng
Published: October 2013

Computation of acoustic radiation from a baffled circular piston continues to be an active area of investigation, both as a canonical problem and because of numerous practical applications. For time-harmonic radiation, exact series expansions are an attractive approach because they do not require numerical integration or limiting approximations. Here, series expansions due to Hasegawa, Inoue, and Matsuzawa [J. Acoust. Soc. Am. 74, 1044–1047 (1983); 75, 1048–1051 (1984)] are shown to reduce to simpler expressions suitable for numerical computations. For the region r≥a, where a is the piston radius and r is the distance from the piston center, an exact solution is given by a series of spherical Hankel functions and Legendre polynomials with explicit, closed-form, position-independent coefficients. For the paraxial region w≤a, where w is the distance from the piston axis, a second exact series expansion is valid for all axial distances z and reduces to the known analytic solution for w=0. These two expansions allow the radiated field to be computed at any point, with rapid convergence except for points near the circle bounding the piston. Example numerical results illustrate application of this method to ultrasonic sources.
Auditory and visual performance in an open sound field
Authors: Fluitt Kim F. , Letowski Tomasz , Mermagen Timothy
Published: October 2013

The ability to estimate a distance to a sound source in an open field is an important element of situational awareness on the battlefield, and is affected by many technical and environmental conditions. A limited body of knowledge regarding auditory perception of sources located over long distances makes it difficult to develop models predicting auditory behavior on the battlefield. Results of previous studies have shown that people greatly underestimate distances. However, it is not known if there is a connection between a visual estimation, verbally reporting an estimate, and auditory estimation. The purpose of the present study was to compare listeners’ visual, verbal reporting, and auditory estimates to sound sources 25 to 200 m from the listening position. Data were collected for auditory as well as visual estimations of distance expressed verbally. Twenty-two subjects (men and women, ages 18–25) participated in the study. Six types of sounds were presented from five loud speakers in random order. Test results indicate that auditory and visual estimation errors increased with distance and that at some distances the visual estimation errors exceeded auditory estimations errors, but the differences were not statistically significant. Specific results will be presented.
Effects of different amounts of brief training and rest on the generalization of learning from interaural-level-difference to interaural-time-difference discrimination
Authors: Ortiz Jeanette A. , Wright Beverly A.
Published: October 2013

Training-induced improvements on perceptual skills can be enhanced by increasing the amount of training and by resting between training and testing. However, how these two factors affect the generalization of learning from a briefly trained condition to an untrained one is unknown. Here, listeners were trained on an interaural-level-difference (ILD) discrimination condition (4-kHz tones), then were tested for generalization to an interaural-time-difference (ITD) discrimination condition (0.5-kHz tones). The amount of training and the time between training and testing differed across four groups. Listeners tested 10 hours after training had significantly lower ITD discrimination thresholds than naive listeners (n=94), regardless of whether training lasted for 20 min (n=14) or 2 hs (n=11). Thus, when there was a long time between training and testing, learning generalized from ILD to ITD discrimination regardless of the amount of training. In contrast, listeners tested immediately after training on ILD discrimination showed generalization to ITD discrimination with 20 min (n=14), but not 2 h (n=14), of training, suggesting that without rest between training and testing, longer training disrupted generalization. Hence, increased training interfered with generalization from ILD to ITD discrimination for short, but not long, delays between training and testing. [Work supported by NIH.]
Modeling inner hair cell compression
Authors: Eustaquio-Martin Almudena , Lopez-Poveda Enrique A.
Published: October 2013

The voltage-dependent activation of inner hair cell (IHC) basolateral potassium (K+) currents results in a compression of voltage responses to injections of large depolarizing currents with values well within the range of IHC transducer currents (Kros and Crawford, J. Physiol. 421, 263–291 (1990)). In vivo, this compression must add to the compressive nonlinearity produced by the gating of transducer channels. The purpose of this work is to present a biophysical model of the IHC that simulates the nonlinear compressive effects of IHC basolateral potassium currents both in vivo and in vitro. The model incorporates two components for the po- tassium currents, one fast and one slow, as described by Kros and Crawford. Membrane parameters are provided for the model to reproduce the time course of the receptor potential in response to constant current pulses across the membrane. The model is then used to investigate the degree of compression that the K+ currents contribute to the receptor potential in vivo. Also investigated are the effects on IHC compression of a partial blocking of the K+ channels, as occurs in some common forms genetic hearing loss. [Work supported by Spanish FIS PI020343 and G03/203.]
Acoustics of Baltic psaltery; a new outstanding Latvian Kokle
Authors: Peekna Andres , Rossing Thomas D.
Published: October 2013

We have studied the acoustics of a Latvian Baltic Psaltery (kokle) which was judged by performing and recording musicians to be outstanding. Previous work by the authors pointed out the importance of a high population of body-resonances within the tuning range of the instrument, with good string-to-resonance coupling also playing an important role. This particular kokle shows outstanding coupling of strings to body-resonances, with all strings evidencing some degree of coupling. In some cases, the strings couple to a superposition of more than one body-resonance.
Modal analysis and computer aided design studies of acoustic guitar structural designs
Authors: Rashkow Craig M. , Collier Robert D. , Carruth Alan
Published: October 2013

This study seeks to systematically identify modern Computer Aided Design (CAD) techniques to optimize acoustic guitar design. The study uses traditional design as a starting point for analysis of variations in materials and bracing structures of the front sound plate. CAD techniques are used to model the guitar and provide a broadband input that allows analysis of its modal response. Design optimization occurs in creating the most favorable modal response of the instrument while still maintaining structural integrity through effective support of the forces created by the strings’ tension in the bridge and neck. The measures chosen to help identify the most favorable response are modal density, magnitude of the response at each mode, and the locations of the largest magnitudes. Increased modal density provides a richer timbre while the amplitude of the response determines the relative intensity of the sound projected. Increased modal response in the upper bout of the instrument can improve the timbre of pitches in the upper frequency range of the instrument. After analyzing these measures for multiple variations and iterations of a selected set of structural parameters, an optimal design is suggested. The results show good agreement between experimental modal measurements and computer-aided design modeling.
Relational acoustic invariance in the single/geminate stop distinction in Japanese
Authors: Hirata Yukari , Whiton Jacob
Published: October 2013

This study addressed an issue in the theory of relational acoustic invariance [Pickett et al., Phonetica 56, 135–157 (1999)]. The question was whether an invariant acoustic property exists for distinguishing Japanese single and geminate voiceless stops across different speaking rates. Four native Japanese speakers produced disyllabic words with single and geminate voiceless stops spoken in a carrier sentence at three speaking rates. Durations of sentences, words, stop closures, and vowels preceding the contrasting stops were measured. Ratios of geminate to single stop closures, geminate words to single words, closures to preceding vowels, and closures to words were calculated. The stop closure duration significantly overlapped between the single and geminate categories across rates. However, the ratio of geminate to single closure duration was unaffected by rate. Among the measures examined, the ratio of closure to word duration (0.35 as an optimal boundary) best classified all single and geminate tokens with 95.7–98% accuracy. These results suggest that, in spite of overlap in absolute closure duration between single and geminate stops, there is a relationally invariant measure that divides the two phonemic categories across rates and speakers, supporting the theory of relational acoustic invariance.
Targetless schwa revisited
Authors: Flemming Edward
Published: October 2013

It has been suggested that schwa vowels in English lack vowel quality targets, that is, they are realized as interpolations between the preceding and following segmental contexts or are the result of separating two consonantal constriction gestures, without an inherent vocalic gesture. Tests of this hypothesis have produced mixed results. The present study revisits the question of schwa targets based on acoustic analysis of schwa vowels in a wider range of segmental and morphological contexts. The main conclusions are: (i) It is important to distinguish stem-final reduced vowels (as in ‘‘pandA’’) from other schwa vowels (e.g., ‘‘About,’’ ‘‘bEgin’’). The former clearly have vowel quality targets they are generally mid central vowels whereas the latter are much more contextually variable. (ii) The variable schwa vowels have a target, but this target is not a particular vowel quality, it is to indicate the presence of a vowel. This is achieved through a variety of means, including duration and realization of a local amplitude peak, but is consistent with substantial variation in vowel quality, particularly F2.
Propagation and reverberation implications of seabed dispersion
Authors: Schmidt Henrik
Published: October 2013

The significance of the seabed geoacoustic properties to shallow water acoustic propagation is well established, and consequently the dispersion, or frequency dependence of the sound speed and the attenuation may be significant to the performance of broadband acoustic systems, whether for acoustic sensing or for communication. On the other hand, it is equally well established that the seabed significance is highly dependent on the system configuration, e.g., source and receiver depths, and the same will therefore obviously be the case for the dispersion. This paper will review the propagation effects of frequency dependent seabed geoacoustics, under characteristic seasonal environmental conditions, and typical system configurations. The associated implications to the acoustic system performance will be discussed in the context of theoretical performance bounds, such as the Cramer-Rao lower bounds, using established wave theory propagation models for range-independent and -dependent environments. Among the specific examples will be the effect of strong sediment dispersion in sandy sediments on buried target detection by low-frequency SAS systems operating in the 1–10 kHz regime, and broadband acoustic communication systems, including the effect of dispersion on seabed reverberation. [Work supported by ONR.]
Ultrasonic tomography for density gradient determination and defect analysis
Authors: Zhao Xiang , Rose Joseph L.
Published: October 2013

Ultrasonic tomography is used to study density gradients and structural defects. In practice, it is not possible to measure an almost infinite number of projections, necessary for the transform-based techniques to produce highly accurate results. To overcome this difficulty, interpolations with respect to sample angle and projection angle based on fewer measurements are used to generate the required projection data. The number of sampled grid values necessary for displaying a well-balanced reconstructed image to reduce the aliasing distortions caused by insufficiency of the input data is then possible. For slowness reconstruction, as an example, one should constrain the time of flight at a source point to zero when using interpolation, other than using extrapolation to generate projection data to guarantee that the interpolated data around the source converges to zero. Hence no time is taken when a source and a detector overlap. Algebraic reconstruction algorithms, however, lack the accuracy when using a smaller number of measurements, and computational efficiency when using an abundant data set generated by interpolating. Results show that this approach can improve the overall accuracy and cost more effectively, thus making it a potentially, powerful tool for studying in-situ process and health monitoring. [Work supported by NSF.]