bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation of rippled-sand sonar imagery with visual and statistical verification.
Authors: Johnson Shawn F.
Published: October 2013

Synthetic aperture sonar (SAS) imagery is often characterized by a decidedly non-Rayleigh pixel amplitude distribution, owing to its inherent high-resolution combined with speckle induced by the coherent image formation process. Recent work has shown increasing the resolution cell size by limiting the image bandwidth typically produces images with statistics tending toward a Rayleigh distribution. A caveat to this generalization is that the trend toward Rayleigh is dependent on orientation of the SAS system to strongly correlated sea-floor structures such as sand-ripples. A method has been developed to simulate rippled-sand sonar imagery at high-frequencies (i.e., on the order of 100 kHz), which accounts for nonsymmetric ripple shape, sediment acoustic properties, sonar to ripple orientation, system resolution, and coherent imaging induced speckle. This numerical simulation method is computationally inexpensive and compares well both visually and statistically with collected data over a wide range of orientation angles. Simulation methods will be presented with verification using SAS imagery collected by the Naval Surface Warfare Center: Panama City Division. [Work supported by ONR Grants No. N00014-04-1-0013 and No. N00014-06-1-0245, and Code 32.]
Introduction to workshop goals.
Authors: Hoover K. Anthony , Brooks Bennett M.
Published: October 2013

Many states require that architects obtain continuing education unit (CEU) credits annually, in order to maintain their registration or licensure. The American Institute of Architects (AIA) Continuing Education System (CES) offers continuing education courses, which may be given by third party providers. The Technical Committee on Architectural Acoustics (TCAA) is an AIA/CES Registered Provider. The goal of this workshop is to prepare members of the TCAA so that they may be authorized to present a short course which can earn attendees CEU credit. In order for TCAA members to qualify to meet the AIA requirements, they must attend this workshop, which is given in two parts. The first part will be devoted to the short course presentation material, which is in a standardized format. The second part of the workshop will focus on the AIA CEU Program registration and reporting requirements. Of course, anyone is free to register with the AIA to provide their own CEU program. However, the advantages of participating in this program are that the TCAA short course is already prepared, is preapproved by the AIA, and the registration fees are paid by the Acoustical Society of America.
Call localization of marine mammals using directional autonomous recorders.
Authors: Blackwell Susanna B. , Greene Charles R. , Nations Christopher S. , McDonald Trent L. , Thode Aaron , Macrander A. Michael
Published: October 2013

Directional sensors of low-frequency acoustic waves have been used by navies in sonobuoys for submarine detection and localization for decades. Composed of an omnidirectional pressure sensor and two horizontal directional elements sensitive to particle motion, they provide information for determining the relative bearing to a sound source without ambiguity. They were adapted for bowhead whale monitoring in the mid-1980s and have been used in autonomous seafloor acoustic recorders since 2000. Applied to the coastal Beaufort Sea north of Alaska, fall bowhead migration was observed in detail during 2007 and 2008, providing a wealth of information on variability in the migration paths of calling whales and the influence of industrial sounds on the locations of calling whales. For example, many calls were detected within about 30 km of seismic survey activities, where received sound pressure levels from airgun pulses were often greater than 140 dB per 1 μPa. Also, seismic activities were correlated with statistically significant shifts in the whales’ distance from shore, either offshore or inshore. However, interpretation of the results was challenged by the difficulty in distinguishing between a whale that ceases calling and a whale that deflects away from the study area. [Work supported by Shell Oil Co.]
Seabed characterization and model based processing: Past, present, and future.
Authors: Siderius Martin
Published: October 2013

One of the most active areas of research in acoustical oceanography has been the study of seabed acoustics. This has been partly motivated by the need for accurate sonar performance prediction, which often depends on knowledge of the seabed properties. There has also been significant research on environmentally adaptive and model based signal processing such as matched field processing. One of the obstacles to model based processing has been the required knowledge about seabed properties, which is needed as input. This dependency, in part, led to the innovation of matched field inversion methods to obtain seabed properties. In recent years, new algorithms have been introduced that use ambient noise (e.g., from breaking waves) as a surrogate sound source to probe the seabed and estimate geoacoustic properties. These noise methods have received much attention since measurements and processing are simple and the results are surprisingly good. In fact, current developments in noise processing may be the key to enabling model based methods that, in the past, were not considered practical. In this presentation a review of seabed inversion methods will be given with discussion about current developments in noise processing and the potential for renewed interest in model based processing.
Treating heterotopic ossification with shockwaves.
Authors: Chang Michael W. , Osathanon Thanaphum , Giachelli Cecilia
Published: October 2013

Heterotopic ossification (HO) is formation of lamellar bone in soft tissue, commonly seen among patients with burns, orthopedic fractures/procedures, brain/spinal cord injuries, muscle contusions, and rare hereditary disorders. Patients with HO experience pain and joint limitations, which further exacerbate their disability. Reduction of HO preventatively and/or for treatment has been attempted using medications, radiation, and surgery with limited success. Recent encouraging clinical HO outcomes using shockwave therapy have been discussed but treatment mechanisms were unclear. Mechanisms such as spallation, cavitation, squeezing, superfocusing, fatigue, and layer separation have been proposed for lithotripsy. Mineralized calcium phosphate macroporous nanofibrous fibrin scaffolds were used as a HO model to study treatment mechanisms. The HO was treated with electrohydraulic shockwave devices. The scaffold calcium contents decreased from 45.4(3.6) (untreated) to 20.9(18.1) (OssaTron, 0.71 mJ/mm2) and 27.5(23.5) ugCa/mg dry weight (EvoTron, 0.46 mJ/mm2) with 200 shocks (1 Hz). Scanning EM of the shockwave-treated HO supports separation of the calcium phosphate from the fibrin matrix probably contributed by shear and cavitation. Biological responses to shockwaves, such as inflammation, neovascularization, angiogenesis may also play important roles in clinical HO treatment. A unique clinical HO case is discussed to illustrate risks, benefits, and challenges from shockwave therapy.
Numerical simulation of propagation of acoustic and elastic waves in human head with fast integral equation solver.
Authors: Bleszynski Elizabeth , Bleszynski Marek , Jaroszewicz Thomas
Published: October 2013

An approach to numerical simulations of acousto-elastic waves in the human head is described, and simulation examples are presented. The primary goal of our work is to construct an efficient and high fidelity numerical simulation tool for investigating such effects as, e.g., acoustic energy transfer to the inner ear via non-airborne pathways. The solver employs a modified form of the volumetric Lippmann–Schwinger integral equation, adapted to high material-contrast problems, and an FFT based stiffness matrix compression implemented for distributed-memory systems enabling large scale (several million unknowns) simulations for realistic geometries. Some of the new aspects of the technique and its applications include (a) extension of the technique for problems involving large density contrasts,in situations involving elastic media; (b)improved, more economical, and more accurate Galerkin discretization scheme involving linear tetrahedral elements; (c) verification of the solver by comparison of its predictions with an exact analytical solution for a sphere composed with layers supporting both compressional and shear waves; (d) applications in representative numerical simulations of mechanisms of energy transfer to the inner human ear and comparative analysis of the pressure distributions in a human head with and without the presence of noise protective devices, carried out with realistic geometry models. [Work supported by AFOSR].
An introduction to bagpipes of the world.
Authors: Wheeler Paul A.
Published: October 2013

When one hears the term “bagpipe,” the Great Highland bagpipe from Scotland comes to mind. There are actually several types of bagpipes played across Europe and the Middle East, each with its unique characteristics. This paper classifies bagpipes from around the world based on their construction and acoustic properties. These include: method of filling the bag (bellows versus mouth pipe), bag properties and materials, reeds (single or double), pipes used for chanters and drones (cylindrical or conical), and general characteristics of the instrument. The objective of this overview paper is to provide the background for more detailed papers in the session on bagpipes.
Stability of monitoring weak changes in multiply scattering media with ambient noise correlation: Laboratory experiments.
Authors: Eric Larose , Celine Hadziioannou , Olivier Coutant , Philippe Roux , Michel Campillo
Published: October 2013

Previous studies have shown that small changes can be monitored in a scattering medium by observing phase shifts in the coda. Passive monitoring of weak changes through ambient noise correlation has already been applied to seismology, acoustics, and engineering. Usually, this is done under the assumption that a properly reconstructed Green function as well as stable background noise sources are necessary. In order to further develop this monitoring technique, we performed a laboratory experiment in the 2.5 MHz range in a gel with scattering inclusions, comparing an active (pulse-echo) form of monitoring to a passive (correlation) one. Our results show that temperature changes in the medium can be observed even if the Green function (GF) of the medium is not reconstructed. Moreover, we establish that the GF reconstruction in the correlations is not a necessary condition: the only condition to monitoring with correlation (passive experiment) is the relative stability of the background noise structure.
The roles of tone and syllable structure in Mandarin spoken word recognition.
Authors: Lai Yuwen , Zhang Jie
Published: October 2013

The present study adopts the gating paradigm to investigate the roles of tone, onset sonorancy, and nasal coda in Mandarin spoken word recognition. Duration-blocked gates generated from eight monosyllabic quadruplets with matching frequencies of occurrence were used as stimuli. The initial consonant of each syllable formed the first gate, with later gates formed by 40 ms increments. Twenty-eight native Mandarin speakers from Beijing were asked to identify each gated stimulus by writing down the Chinese characters. Isolation point (IP) based on correct tone identification as well as overall correct word identification (correct onset, rhyme, and tone) were collected. Results from both conditions showed that tone 1 has an earlier IP than tone 4, which has an earlier IP than tones 2 and 3. Sonorant-initial syllables have an earlier IP than obstruent-initial syllables, but further analyses of covariance indicated that this is due to the fact that IP covariates with the duration of the initial consonant. Syllables without a nasal coda have an earlier IP than syllables with a nasal coda. This effect might be due to the interference of nasalization on tone perception or the delayed tonal contour realization due to the nasal coda [Xu, (1998)].
Auditory-phonetic projection and lexical structure in the recognition of sine-wave words.
Authors: Remez Robert E. , Dubowski Kathryn R. , Broder Robin S. , Davids Morgana , Grossman Yael S. , Moskalenko Marina , Pardo Jennifer S. , Hasbun Sara Maria
Published: October 2013

Speech remains intelligible despite the elimination of canonical acoustic correlates of phonemes from the spectrum. Listeners tolerate distortion or spectral blur in tone analogs, noise band vocoded speech, and acoustic chimeras in utterances ranging from syllables to isolated words and sentences. A portion of this flexibility is attributable to short-term perceptual learning in auditory-to-phonetic projection, though exploiting the properties of lexical neighborhoods plays a role with utterances composed of words. New tests were conducted to estimate talker learning, segmental sensitivity, and lexical knowledge in this kind of perceptual versatility. Sine-wave versions of the easy/hard word lists were created, and the performance-level difference between the two lists was used to index the default reliance on lexical processes. Several kinds of preliminary exposure were used to induce sensitivity to a dimension of perceptual learning: sine-wave speech produced by the same talker, sine-wave speech of a different talker, natural speech of the same talker. A comparison of exposure effects on the performance level of easy/hard word recognition offered a clue about the differential contribution of talker-based, segment-based, and lexically-based attention in speech perception without canonical spectra. Implications for perceptual accounts based on cue likelihood will be discussed. [Work supported by NIDCD.]
Perceptual normalization for variation in speaking style.
Authors: Vitela Antonia D. , Sullivan Sarah C. , Lotto Andrew J.
Published: October 2013

Ladefoged and Broadbent [J. Acoust. Soc. Am. 29, 98–104 (1957)] demonstrated that listeners will shift their categorization of a target vowel as a function of acoustic characteristics of a preceding carrier phrase. These results have been interpreted as an example of perceptual normalization for variability resulting from differences in talker anatomy. The present study examined whether listeners would normalize for acoustic variability resulting from differences in speaking style within a single talker. Two vowel series were synthesized that varied between central and peripheral vowels (the vowels in “beat”-“bit” and “bod”-“bud”). Each member of the series was appended to one of four carrier phrases that were spoken in either a “clear” or “reduced” speech style. Participants categorized vowels in these eight contexts. A reliable shift in categorization as a function of speaking style was obtained for three of four phrase sets. This demonstrates that phrase context effects can be obtained with a single talker. However, the directions of the obtained shifts are not reliably predicted on the basis of the speaking style of the talker. Instead, it appears that the effect is determined by an interaction of the average spectrum of the phrase with the target vowel. [Work supported by NIH-NIDCD.]
An investigation of brain activation patterns in response to speechreading.
Authors: Auer Edward T.
Published: October 2013

The ease of recognizing spoken words on the basis of optical input alone, or speechreading, is known to systematically vary as a function of the properties of the stimulus materials. The current study investigated the relationship between cortical responses and the intelligibility of the stimulus materials. Open-set identification performance outside the magnet was used to directly measure the intelligibility of the stimulus materials presented in the magnet as well as participant speechreading ability. fMRI was used to measure cortical response to viewing spoken word stimuli that were predicted to vary in their ease of identification. Videos of spoken words were contrasted with still face images in a block-design fMRI experiment. Blocks containing sets of words predicted to be easy speechread were contrasted with blocks predicted to be difficult to speechread. Preliminary analyses of cortical response to speechreading are consistent with previous studies [Hall et al., J. Cog. Neuro. 17(6), 939–953 (2005)]. Furthermore, evidence of increased activation in BA 37 and BA 44 for easy words versus hard words was obtained. These results are consistent with the hypothesis that specific areas are sensitive to the intelligibility of speech read stimuli. [Work supported by a grant from NIH/NIDCD (R01DC04856).]
Does training improve consistency of roughness judgments in a matching task?
Authors: Eddins David A. , Shrivastav Rahul , Patel Sona A.
Published: October 2013

Shrivastav et al. [J. Acoust. Soc. Am. 119(5), 3340 (2006)] reported a matching task in which a square wave modulated sawtooth wave (signal) was matched to a series of vowels (standards) to estimate the magnitude of roughness in voices. Results suggested that listeners found it difficult to isolate roughness from other voice quality dimensions such as breathiness. In the present experiment, a brief training session was added prior to the matching task to ensure that listeners were attending to variations in roughness alone. This training consisted of a rank-ordering task in which listeners sorted the 34 test samples of the vowel /a/ in ascending order of roughness. For feedback, these rankings were compared to the rankings made by expert listeners. This criterion was used to ensure that all participants understood the dimension of voice quality under study. Listeners who met a specific eligibility criterion completed a modulation matching task to familiarize them with the matching task itself. Finally, thresholds for the roughness matching task were obtained and compared to thresholds obtained without training. The extent to which task-related training can help listeners make perceptual judgments for specific dimensions of voice quality will be discussed.
Propagation focusing in the context of clutter statistics.
Authors: Harrison Chris
Published: October 2013

Fluctuations in reverberation (clutter) from scatterers at long range in shallow water can be affected by many mechanisms. Their statistics, in particular the scintillation index, depend not only on the statistics of the scatterers (their physical distribution, shape, orientation, etc.) but on the outward and return propagation paths. Focusing effects due to forward scattering from weak undulations in the seabed will be presented. Existing Fresnel–Kirchhoff theory for monostatic, vertical incidence on a two-dimensional surface is adapted to demonstrate the behavior of the intensity’s scintillation index in bistatic geometry. In addition, using a simulation of bistatic geometry and a one-dimensional surface, the intensity statistics are extended to include autocorrelation function and probability distribution. Bistatic geometries include source and receiver moving with constant separation, and moving source with fixed receiver. Fairly modest vertical undulations can result in significant fluctuation due to reflection focusing with scintillation indices possibly greater than unity.
Annual temporal patterning in the vocalizations of captive seals: Two long-term case studies.
Authors: Reichmuth Colleen , Schusterman Ronald J.
Published: October 2013

Seasonal changes in vocalizations occur in a variety of species. Factors such as the condition of conspecifics, physiological states that in turn may be related to environmental cues, and developmental and individual differences all potentially influence temporal changes in sound production. In the present study, the vocal behavior of two captive seals was monitored daily for over 10 yrs. Both seals were housed in the absence of conspecifics from the age of 1 yr extending past sexual maturity. The male harbor seal (Phoca vitulina) began characteristic underwater vocal displays at the age of 6. Intense periods of acoustic activity lasted weeks to months, overlapped with the breeding activity of local harbor seals, and comprised stereotypic sound emissions that were structurally similar to those reported for wild seals. The female northern elephant seal (Mirounga angustirostris) produced aberrant intense airborne vocalizations from the age of 4 that were annually synchronized to a period of approximately 5 weeks coinciding with estrous. Endogenous changes appear to trigger these behavioral cycles, presumably as a result of hormonal changes associated with photoperiod. Vocalizations may be a noninvasive indicator of reproductive state and therefore may provide a useful management and conservation tool in captive settings.
A comparison of behavioral and electrophysiological measures of aerial hearing sensitivity in a Steller sea lion (Eumetopias jubatus).
Authors: Mulsow Jason , Reichmuth Colleen
Published: October 2013

A number of studies with odontocete cetaceans have demonstrated that hearing sensitivity measurements using electrophysiological auditory steady-state responses (ASSRs) can provide an efficient means of estimating a subject’s behavioral audiogram. Expansion of ASSR methods to another marine mammal group, the otariid pinnipeds (sea lions and fur seals), holds the potential to increase the number of otariid individuals and species for which hearing sensitivity data are available. A within-subject comparison of ASSR and behavioral measures of aerial hearing sensitivity was conducted with an individual of the largest otariid species, the Steller sea lion. Psychophysical methods were used to obtain an unmasked aerial audiogram at 13 frequencies spanning a range of 0.125 to 34 kHz. Corresponding ASSR thresholds measured at frequencies of 1, 2, 5, 10, 20, and 32 kHz had differences (relative to behavioral thresholds) ranging from 1 dB at 20 kHz to 30 dB at 1 kHz. Overall, the ASSR audiogram was a fairly accurate predictor of the behavioral audiogram at frequencies of 2 kHz and above. Our results suggest that ASSR methods can be appropriately applied to otariid pinnipeds in estimating aerial sensitivity at frequencies of approximately 2 kHz and above.
Model for bubble dynamics in liquid near an elastic tissue interface.
Authors: Hay Todd A. , Zabolotskaya Evgenia A. , Ilinskii Yurii A. , Hamilton Mark F.
Published: October 2013

A model is under development for the weakly nonlinear dynamics of a bubble in a blood vessel surrounded by tissue with elasticity and losses. The model requires knowledge of the radiation impedance of the bubble within the vessel, which is determined by the Green’s function. As a first step toward this objective, the Green’s function is derived for a bubble in a liquid half-space bounded by an elastic half-space. The method used to derive the Green’s function follows an approach described previously for the response of an acoustically driven object in an elastic half-space [Zabolotskaya et al., J. Acoust. Soc. Am. 124, 2514(A) (2008)]. The Green’s function is expressed in terms of its angular spectrum in a plane parallel to the interface, resulting in ordinary differential equations in the coordinate normal to the interface. Boundary conditions are satisfied at the interface and in the plane containing the source to obtain solutions of the differential equations, the inverse spatial Fourier transform of which yields the desired Green’s function. Extension to multiple layers of tissue is straightforward. Calculations will be presented for the radiation impedance of the bubble near the interface. [Work supported by the ASA Hunt Fellowship and NIH DK070618.]
Dissolution and stabilization of contrast microbubble by its elastic shell.
Authors: Sarkar Kausik , Katiyar Amit
Published: October 2013

We have developed a model for gas transport from encapsulated contrast microbubbles used for ultrasound imaging and drug delivery. The model explicitly accounts for permeability of gas through encapsulation and encapsulation elasticity. We use it to investigate dissolution time and stability of a lipid-coated perfluorocarbon bubble such as Definity. Realistic values of material properties such as diffusivities, permeabilities, and Ostwald coefficients of air and octafluoropropane were used to find that the lifetime of hours for such a bubble is only possible at extremely low surface tension in the absence of shell elasticity. Dissolution dynamics is investigated for effects of various parameters such as initial mole fraction of octafluoropropane, initial radius, surface tension, and shell permeability. The dissolution dynamics scales with permeability, in that when the time is nondimensioanlized with permeability, curves for different permeabilities collapse on a single curve. For an elastic shell, one obtains stable bubbles when the appropriate condition on surface tension and encapsulation elasticity is satisfied. The condition varies with the level of air saturation of the surrounding medium. For the oversaturated case, the dynamics allows multiple branches of equilibrium solutions. Stability of these branches are numerically investigated and discussed.
Physical modeling of the piano: An investigation into the effect of string stiffness on the hammer string interaction.
Authors: Saitis Charalampos , Orr Sarah , van Walstijn Maarten
Published: October 2013

The stiff string wave equation has four solutions, two of which are fast-decaying waves introduced by the string stiffness. In the case of digital waveguide modeling of piano strings these are normally neglected. Some recent reports have suggested that all four traveling waves should be considered, at least at the neighborhood of interaction points (i.e., the hammer and the boundaries). This paper investigates the effect of omitting string stiffness in the context of sound synthesis of the piano by physical modeling. A stiff, lossy string with a spatially distributed hammer force excitation is implemented using both a finite-difference time-domain scheme and a digital waveguide model. The two models are designed so as to have the exact same features but for the two stiffness-related solutions. Numerical experiments are employed to study the contact force and string velocity signals for different initial hammer velocity values. The results generally confirm that the two fast-decaying waves have only a marginal effect on the overall string motion. However, small audible differences result for bass strings struck with high initial hammer velocities.
Predicting structure-borne noise for new construction adjacent to medical facilities.
Authors: Carman Richard A. , Glickman Gary M.
Published: October 2013

When new building construction is conducted in close proximity to existing medical or medical research facilities, structure-borne noise due to construction activities generating vibration can cause impacts to the occupants of the existing building. Theoretical modeling of structure-borne noise is very complicated and can be extremely time consuming. The feasibility of the two primary candidates (i.e., FEA and SEA) for modeling this phenomenon is questionable, at least at this point, for a number of reasons that are discussed. It is possible that the time will come when a theoretical method can be used reliably to predict structure-borne noise transmission. In the meantime, using an empirical approach seems to be the most viable. A case study is presented of a facility for medical research involving mice. Preconstruction projections of structure-borne noise and vibration are compared to those measured with an extensive monitoring program employed during construction.
Vibration sensitivity of optical microscopes in the healthcare setting.
Authors: Amick Hal , Gendreau Michael
Published: October 2013

The paper examines vibration criteria for benchtop and articulated floor-supported optical microscopes, comparing published specifications with data measured in hospitals for diagnostic purposes. A case study of vibrations that degraded orthopedic microsurgery is of particular interest. Revisions and enhancements of published criteria are proposed.
Parametric acoustic arrays: A Bergen view.
Authors: Hobæk Halvor
Published: October 2013

At the University of Bergen (UoB), Norway, research activity in physical acoustics started in the mid-1960s with investigations on the parametric acoustic array (PAA). The newly appointed professor in applied mathematics, Sigve Tjo/tta, had some years earlier been at Brown University and was inspired by the concept at a fundamental level, but also wanted experimental confirmation. No previous acoustical activity existed at UoB. The PAA project was started as a master project at Department of Physics, where the main activity was in nuclear, high-energy, and ionospheric physics. Bellin and Beyer’s experiment served as a model. The results provided new information on the axial and directional properties of the difference frequency wave field. Inspired by this, theoretical modeling continued along with further measurements. Other nonlinear effects like acoustic streaming (boundary layer, density gradient) were also investigated. In 1975, a project together with SIMRAD and Norwegian Technical University resulted in a bottom penetrating PAA, later commercialized as “TOPAS.” Numerical modeling based on the KZK equation resulted in the “Bergen Code,” still in use for computing nonlinear acoustic propagation problems. In later years activity at UoB has expanded to encompass linear physical acoustics of various sorts, occasionally using PAA as a tool.
Revealing and quantifying temporal aspects of envelopes of high-frequency stimuli that lead to enhanced processing of interaural temporal disparities.
Authors: Bernstein Leslie R. , Trahiotis Constantine
Published: October 2013

This presentation concerns evaluating which aspects of envelopes of high-frequency waveforms foster efficient discrimination of interaural temporal disparities (ITDs). The experiments were designed to assess, quantitatively, the explanatory capability of metrics including: (1) the normalized fourth moment of the envelope (Y), (2) the normalized interaural correlation of the envelope, and (3) the dead time between peaks or maxima of the envelope. An ITD-discrimination study was conducted employing raised-sine stimuli centered at 4 kHz [John et al., Ear and Hearing 23, 106–117 (2002)]. The parameters of the stimuli that could be varied using such stimuli include: (1) the exponent of the raised sine, (2) the frequency of modulation, (3) the depth of modulation, (4) the degree of phase-scrambling applied to the spectral components of the envelope, and (5) the degree of phase-scrambling applied to the spectral components of the waveform. This set of parameters permitted us to construct an ensemble of stimuli that pit one metric against another in a manner that reveals the relative salience of particular temporal aspects of the envelope. Results will be discussed both in terms of the characteristics of the external, physical stimuli versus the stimuli as processed by the auditory periphery. [Research supported by research Grant Nos. NIH DC-04147 and DC-04073 from the National Institute on Deafness and Other Communication Disorders, National Institutes of Health.]
Real-virtual equivalent auditory localization with head motion.
Authors: Romigh Griffin D. , Brungart Douglas S.
Published: October 2013

Several researchers have shown that individualized head related transfer functions (HRTFs) can be used to produce virtual sounds that are equivalent in terms of localization to free field sounds. Thus far, however, these results have only been shown in studies that have required listeners to keep their heads stationary during the playback of the virtual sounds. In this study, we investigated the performance limits of a virtual auditory display system that incorporated individualized HRTFs but allowed free head motion during the localization process. One key aspect of the system is a high-speed HRTF measurement process that allowed a full set of individualized HRTFs to be measured in less than 4 min. This made it possible to make an HRTF recording and complete a localization task using the resulting HRTFs within the same 30-min experimental session. The results show that equivalent free-field and virtual localization performance was achieved when the virtual sounds were generated in the same session using specially-designed open-ear headphones that did not need to be removed during the headphone equalization process. This indicates that equivalent real-virtual closed-loop localization is possible even with the truncated, interpolated, minimum-phase HRTF filters that are required for practical, real-world virtual audio systems.
Vowel-inherent spectral change enhances adaptive dispersion.
Authors: Kluender Keith R. , Stilp Christian E. , Rogers Timothy T. , Kiefte Michael
Published: October 2013

Despite wide diversity among particular vowel sounds used across the world’s languages, there are profound systematicities across languages. Whether sets of three, five, seven, or more vowel sounds are used, vowels that comprise these sets have substantial commonality across languages. Using static measures of vowel spectra, Lindblom and colleagues have demonstrated principles of adaptive dispersion through which the compositions of vowel inventories can be predicted on the basis of maximizing perceptual distinctiveness among the vowels within a language. Here, we address whether introduction of vowel-inherent spectral change is consistent with principles of optimizing perceptual distinctiveness between vowels. We find that vowel-inherent formant trajectories generally serve to further disperse vowel sounds across time. Trajectories of formants for vowel sounds that are relatively close in static measures (formant center frequencies: beginning, center, end) tend to be relatively distinct as measured by angles in F1, F2, F3 coordinates. In a complementary fashion, vowels that share similar trajectories have relatively distinct static characteristics. This perceptual efficacy of vowel-inherent spectral change maintains across multiple place-of-articulation contexts. Across the vowel space and across consonantal contexts, vowel-inherent spectral change serves to increase adaptive dispersion and enhance perceptual distinctiveness. [Work supported by NIDCD.]
Vowel-inherent spectral change and the second-language learner.
Authors: Rogers Catherine L. , Glasbrenner Merete M.
Published: October 2013

Relatively few studies have directly examined the use of vowel-inherent spectral change by second-language learners, perhaps because it represents one of the subtler cues to vowel identity. Nevertheless, understanding non-native listeners’ perception of this cue and its integration with other cues to vowel identity can be regarded as a method of investigating the mastery of cues to vowel perception that is needed for native-like perception. While several studies of second-language speech perception have demonstrated differences in cue use by second-language learners, our investigation of the use of dynamic spectral cues and temporal cues by native and non-native listeners suggests that relatively early learners of English as a second language do not appear to use the dynamic spectral cue differently from native English speakers when other cues are preserved. Instead, early learners’ vowel perception appears to be less robust to removal of multiple cues. This apparent difference in even early learners’ ability to use cues to vowel identity independently of one another or to change listening strategy when one cue is degraded may explain a portion of the increased challenge that even relatively early learners of a second language appear to experience in understanding speech in noisy environments. [Work supported by NIH.]
Coherent space-time-frequency processing to enhance the bistatic detection and classification of elastic shells in shallow water.
Authors: Anderson Shaun D. , Sabra Karim G.
Published: October 2013

For underwater sonar, time-frequency analysis has been shown to be a powerful tool for detection and classification of man-made targets. For instance, with traditional monostatic systems, a key energetic feature of spherical shell is the coincidence pattern, or midfrequency enhancement, that results from antisymmetric Lamb-waves propagating around the circumference of the shell. The development by the Navy of mine countermeasure sonar systems, using a network of autonomous systems, provides a mean for multiple bistatic measurements, and thus potentially bistatic enhancement for target detection. However, time-frequency representations of bistatic simulations of scattered signals from spherical shell show that this coincidence pattern typically shifts in both time and frequency with respect to the monostatic case. Hence, this time-frequency shift is challenging for bistatic target detection algorithms based on standard array processing techniques. Design of robust multistatic sonar system based on the generalized space-time-frequency coherence of the bistatic measurements will be discussed. The influence of the source-receiver configuration and interface reflections on the proposed approach have been investigated numerically and experimentally using data collected in shallow water with an elastic spherical shell [Work supported by ONR Code321, N000140810087.]
Wavguide invariant-based characterization of wideband active sonar clutter discretes.
Authors: Goldhahn Ryan , Krolik Jeffrey , Holland Charles W.
Published: October 2013

In active sonar, clutter discretes can produce strong, target-like returns which often produce false alarms of water column targets. While false alarm reduction methods based on statistical feature-based classifiers often lack sufficient training data, matched-field based classifiers often suffer from model mismatch. A waveguide invariant-based approach for estimating the magnitude short-time Fourier transform (STFT) of reverberation returns was presented [Goldhahn et al., J. Acoust. Soc. Am. 124(5), 2841–2851, (2008)]. In this paper, the waveguide invariant properties of the reverberation are used to predict the frequency selective fading of strong clutter discretes. In particular, comparison of waveguide invariant-based magnitude STFT estimates are compared with predictions made using a model of frequency-selective fading from a clutter discrete. The results are further compared with real sonar returns collected during the SCARAB98 experiment off a shipwreck in the Malta Plateau. The results suggest that when accurate characterization of the geoacoustic environment are available, the estimated STFT magnitude spectrum obtained by using a propagation and scattering model compare favorably with those obtained by averaging the reverberation along waveguide invariant striations. [Work supported by ONR.]
Acoustical designs in a new children’s hospital.
Authors: Babineau Francis
Published: October 2013

The importance of noise control and acoustic comfort in healthcare facilities has been well documented. This issue is even more critical in pediatric facilities, given the often frightening and stressful circumstances associated with a child being in a hospital. Recently, The Children’s Hospital in Denver, CO constructed a new facility in neighboring Aurora, CO. The new facility was opened in Oct. 2007, and one of the design goals was to improve the acoustic environment by implementing evidence-based design strategies. However, one of the challenges in improving hospital acoustics is to do so without introducing additional infection control risks. As part of the project, a series of noise measurements were performed at the old hospital and in analogous locations in the new hospital, after the new hospital was occupied. This paper will present the results of the noise measurements and discuss the impact (positive and negative) of various design elements on the acoustic environment.
A comparison of sound transmission loss on metal stud partitions as the stud configuration changes.
Authors: Betit Aaron
Published: October 2013

The draft “Interim sound and vibration design guidelines for hospital and healthcare facilities” drafted by the Joint Subcommittee on Speech Privacy of the ASA recommends STC 50 partitions between exam rooms with no masking sound provided. These partitions are typically constructed of multiple layers of gypsum board on single steel studs, which are widely believed to achieve the required ratings based on published test reports. However, virtually all laboratory testing is with 25 gauge studs 24 in. on center, whereas with a 15 ft floor to floor height typical of hospitals, 16 in. gauge studs installed 16 in. on center are often required for structural reasons. There is little published data on the changes in sound transmission loss changes with stud gauge and spacing. A testing program was established, and transmission loss (STC) tests were performed on drywall partitions with various configurations of stud gauges, spacing, and layers of drywall. Measureable decrease in transmission loss as the studs become heavier and as the spacing between studs decreases was measured. The results of the testing program are presented.
Noise inside a government owned hospital.
Authors: Beristain Sergio
Published: October 2013

A hospital is under evaluation in order to find out the most important noise sources. Noise measurements were carried out within and outside of the hospital, It was found that noise from the neighborhood was not an issue, but noises from within the hospital were loud enough to cause at least some disturbance to the patients and workers. Obviously the larger noise was the one coming from the machinery room, where the laundry, emergency power plant, etc., are located, but also in some of the most important care and treatment rooms, the noise generated inside was well over of the recommended limits for an installation of this type. Some measurement results are presented together with the description of the environment.
Correlation of subjective and objective measures of spectral quality.
Authors: Kelley Dakota M. , Wang Lily M.
Published: October 2013

Common indoor noise criteria with spectral quality indicators have been compared to task performance and subjective noise perception. The analysis seeks to identify a relationship between criteria spectral quality ratings and human perception of common heating, ventilating, and air conditioning background noises. The three criteria evaluated include Balanced Noise Criteria, Room Criteria, and Room Criteria Mark II, due to their inclusion of rumble, hiss, or roar classifications. Study participants worked on typing, math, and verbal tasks while being exposed to various background noise signals, and then completed a questionnaire to describe their perception of the room acoustics. During the data analysis, background noise signals with a non-neutral spectral quality rating were weighted according to their respective spectral indicator, with greater weighting given to lower-frequency signals. Results demonstrate relationships between spectral quality designation and subjective perception of noise fluctuation and tonality. However, a relationship was not found between spectral quality designation and subjective perception of the same parameters (rumble, hiss, or roar). These findings warrant further investigation of the correlation between common criteria ratings and subjective perception. [Work supported by the Univ. of Nebraska Undergraduate Creative Activities and Research Experience Grant.]
Social context influences acoustic communication in zebra finches.
Authors: Vignal Clementine , Elie Julie , Soula Hedi , Mathevon Nicolas
Published: October 2013

During communication, a signal conveys information between an emitter and a receiver, but indirect receivers can eavesdrop on the interaction. In birds, communication has been demonstrated to often be under the influence of this eavesdropping. Social species show complex communication networks where audience drives individual behaviors. Zebra finches (Taeniopygia guttata) are gregarious songbirds that live in social groups and form life-long pair-bonds. Previous studies showed that the vocal behavior of males highly depends on this audience effect. Males show mate calls preference over other female calls in the presence of an established male-female pair, but not in the presence of unmated male-female or male-male dyads. Males in social groups also show stronger vocal response to female calls than males in social isolation. In this study, we investigate whether female calls of varied social salience evoke differently male calling according to the audience. We show that social context modifies not only call rate in response to female calls of varied social salience, but also acoustic structure of evoked calls. Thus male distance calls are not stereotyped calls whose acoustic cues only convey bird’s identity. We propose that fine spectral modifications of the calls could carry information about the emitter motivation.
Direct numerical simulations of bubble collapse near a tissue surface with the ghost fluid method.
Authors: Takahira Hiroyuki , Kobayashi Kazumichi
Published: October 2013

The collapse of an air bubble induced by the interaction of an incident shock wave with the bubble near a gelatin or bone surface is investigated by using an improved Ghost Fluid Method (GFM). The motions of three phases for air inside the bubble, water, and gelatin (or bone) are solved directly by coupling the GFM with the level set method. The results show that the strong shock waves are generated not only when the bubble rebounds but also when the liquid-jet impacts the downstream surface of the bubble; the shock waves result in the depression of the gelatin (or bone) surface. Also, the penetration of the bubble into the depression of the gelatin surface is simulated successfully, which is in qualitative agreement with the experiment by Kodama and Takayama [Ultrasound in Med. & Biol. 24, 723–738 (1998)]. It is also shown that the impulsive pressure at the bone surface caused by the bubble collapse is higher than that at the gelatin surface because the bubble collapse is accelerated by the high-pressure field generated by the reflection of the incident shock wave at the bone surface.
“The Grand Canyon” versus “Soundscape of Nowhere (continued)”.
Authors: Hingson Dickson J.
Published: October 2013

More than 21 years have elapsed since the National Parks Overflights Act mandated the prompt “substantial restoration” of the natural quiet of the aircraft-noise imperiled soundscape of the Grand Canyon National Park. However, as of 2008, long-anticipated, critical compliance benchmarks have still not been timely met in the Park. The past two Administrations have not conformed to specifications/standards/deadlines set or appropriate to the NPS under its legal mandates. However, every battle has its turning point. Will 2009 be the turning point to a quiet Canyon? Success will require immediate NPS application of long-established restoration standards (based on “audibility”), Park zoning considerations, and buttressing with emerging supplemental noise indicators, which trigger loudness and temporal impulsiveness mitigations. Effectiveness of imminently anticipated management actions in the form of a soon forthcoming 2009 environmental impact statement and stepped up political oversight will be examined. These will pit restoration of the authentic Grand Canyon wilderness soundscape against the current, unsavory option: “the Soundscape of Nowhere.” The protracted Grand Canyon imbroglio illuminates similarly unmet, pressing restoration needs, along with the need for increased executive/congressional oversight, re low-altitude air tour noise unacceptably continuing at similarly impacted, famed national parks, which otherwise remain subject to long-term, aviation noise impairment.