bluuebunny/crossref_metadata_2025 huggingface dataset:
Sex differences present in auditory looming perception, absent in auditory recession
Authors: Neuhoff John G. , Seifritz Erich
Published: October 2013

When predicting the arrival time of an approaching sound source, listeners typically exhibit an anticipatory bias that affords a margin of safety in dealing with looming objects. The looming bias has been demonstrated behaviorally in the laboratory and in the field (Neuhoff 1998, 2001), neurally in fMRI studies (Seifritz et al., 2002), and comparatively in non-human primates (Ghazanfar, Neuhoff, and Logothetis, 2002). In the current work, male and female listeners were presented with three-dimensional looming sound sources and asked to press a button when the source was at the point of closest approach. Females exhibited a significantly greater anticipatory bias than males. Next, listeners were presented with sounds that either approached or receded and then stopped at three different terminal distances. Consistent with the time-to-arrival judgments, female terminal distance judgments for looming sources were significantly closer than male judgments. However, there was no difference between male and female terminal distance judgments for receding sounds. Taken together with the converging behavioral, neural, and comparative evidence, the current results illustrate the environmental salience of looming sounds and suggest that the anticipatory bias for auditory looming may have been shaped by evolution to provide a selective advantage in dealing with looming objects.
Spatial perception of motion-tracked binaural sound
Authors: Melick Joshua B. , Algazi V. Ralph , Duda Richard O.
Published: October 2013

Motion-tracked binaural sound reproduction extends conventional headphone-based binaural techniques by providing the dynamic cues to sound localization produced by voluntary head motion [V. R. Algazi, R. O. Duda, and D. M. Thompson, J. Aud. Eng. Soc. 52, 1142–1156 (2004)]. It does this by using several microphones to sample the acoustic field around a dummy head, interpolating between the microphone signals in accordance with the dynamically measured orientation of the listener’s head. Although the provision of dynamic cues reduces the sensitivity of the method to characteristics of the individual listener, differences between the scattered field produced by the dummy head and the scattered field that would be produced by a particular listener distorts the spatial perception. A common observation is that sound sources appear to rise in elevation when the listener turns to face them. We investigate this effect by comparing the perceived rise in elevation under three different conditions: recordings in which recordings are made using (a) the listener’s own head, (b) a KEMAR mannequin, and (c) a cylindrical head with no torso. Quantitative results are presented showing the degree to which perceptual distortions are least for (a) and greatest for (c). [Work supported by NSF.]
The rational function approximation for fluid loaded vibrating structures
Authors: Feit David
Published: October 2013

A complicating feature of fluid-structure interaction problems is the non-local or long-range effect of the fluid loading acting on a structure vibrating in response to time-harmonic loading while submerged in an acoustic medium. DiPerna and Feit [J. Acoust. Soc. Am. 114, 194–199 (2003)] recently introduced an approximation for this effect using a rational function approximation (RFA) to the spectral impedance. The latter relates the transform of the surface pressure to that of the surface velocity, and transforming back to the physical domain gives rise to a high-order differential pressure-velocity relationship. The coefficients of the nth order differentials are inversely proportional to the nth order of frequency so that the approximation gets better with increasing frequency. The approximation originally developed for a planar vibrating surface, has now been extended to a cylindrical surface, and this development and several applications of the RFA technique are presented. [Work supported by the Carderock Division Naval Surface Warfare Center Intra-laboratory Independent Research (ILIR) program and the Office of Naval Research.]
Vibroacoustic optimization of skin damped structures for noise reduction
Authors: Zoghaib Lionel
Published: October 2013

Most of the time the widely used passive treatments are designed to obtain the highest achievable damping. Although this might be satisfactory from a vibrational point of view the approach is not optimal for noise reduction. The idea is illustrated in the case study of a plate on which polymer/aluminum thin patches have been bonded. The system acoustic pressure and structure displacement equations are transformed into a single integro differential one governing the plate displacement. The solution is then expanded into a series of resonance modes. These modes are estimated using a perturbation expansion with respect to the fluid/solid density ratio. Numerically, in vacuo resonance modes are firstly computed using a viscoelastic incompressible 3D FE program together with a Newton-type iterative method and a sparse complex matrix solver implementing ARPACK. Radiation modal impedances are then computed to ponderate the in vacuo solution. The numerical model has been experimentally validated. Its specificity lies in the separate computation of three damping components: thermoelastic, skin and acoustic damping, this last one being caused by the fluid/structure coupling. Finally an optimization process determines an optimal system configuration to achieve the lowest acoustic damping while obtaining the highest viscoelastic damping.
One hundred years of instrumental phonetic fieldwork on North America Indian languages
Authors: McDonough Joyce
Published: October 2013

A resurgence of interest in phonetic fieldwork on generally morphologically complex North American Indian languages over the last 15 years is a continuation of a tradition started a century ago with the Earle Pliny Goddard, who collected kymographic and palatographic field-data between 1906–1927 on several Athabaskan languages: Coastal Athabaskan (Hupa and Kato), Apachean (Mescalero, Jicarilla, White Mountain, San Juan Carlos Apache), and several Athabaskan languages in Northern Canada (Cold Lake and Beaver); data that remains important for its record of segmental timing profiles and rare articulatory documentation in then largely monolingual communities. This data in combination with new work has resulted in the emergence of a body of knowledge of these typologically distinct families that often challenge notions of phonetic universality and typology. Using the Athabaskan languages as benchmark example and starting with Goddard’s work, two types of emergent typological patterns will be discussed; the persistence of fine-grained timing and duration details across the widely dispersed family, and the broad variation in prosodic types that exists, both of which are unaccounted for by phonetic or phonological theories.
Glottalized resonants in NLe kepmxcin (Thompson River Salish)
Authors: Shaw Patricia A. , Campbell Fiona M. , Ehrhardt Flora
Published: October 2013

This study examines properties of glottalized resonants (/m’, n’, l’, y’, w’/) in NLe?kepmxcin, a Northern Interior Salish language, both comparing them with their plain counterparts (m, n, l, y, w) and considering contextual factors as defined by word, syllable, and prominence positions. Despite the relative cross-linguistic rarity of glottalized resonants, they are of considerable theoretical interest given that several recent studies [e.g., Bird and Caldecott, Proceedings of the 10th AICSST (in press)] indicate that their articulatory and acoustic realization may vary significantly across languages and contexts. Of particular relevance to the present study is Carlson, Esling, and Harris’ [UMOPL 17, 58–71 (2004)] claim that in NLe?kepmxcin ‘‘glottalized resonants are a sequential combination of the resonant plus [glottal stop]’’ [pg. 64]. Based on the analysis of glottalized resonants in this study, it appears that the picture is more complex than consistent post-glottalization. Of special interest are glottalized resonants in word-initial position, both because this class is seriously under-represented in the previous literature, and because its characteristics challenge Carlson, Esling, and Harris’ sequencing generalization. Understanding the organization of glottalized resonants will help clarify both sequential and markedness issues in NLe?kepmxcin phonology. [Work supported by SSHRC.]
Wavelet based detection of manatee vocalizations
Authors: Gur Berke M. , Niezrecki Christopher
Published: October 2013

The West Indian manatee (Trichechus manatus latirostris) has become endangered partly because of watercraft collisions in Florida’s coastal waterways. Several boater warning systems, based upon manatee vocalizations, have been proposed to reduce the number of collisions. Three detection methods based on the Fourier transform (threshold, harmonic content and autocorrelation methods) were previously suggested and tested. In the last decade, the wavelet transform has emerged as an alternative to the Fourier transform and has been successfully applied in various fields of science and engineering including the acoustic detection of dolphin vocalizations. As of yet, no prior research has been conducted in analyzing manatee vocalizations using the wavelet transform. Within this study, the wavelet transform is used as an alternative to the Fourier transform in detecting manatee vocalizations. The wavelet coefficients are analyzed and tested against a specified criterion to determine the existence of a manatee call. The performance of the method presented is tested on the same data previously used in the prior studies, and the results are compared. Preliminary results indicate that using the wavelet transform as a signal processing technique to detect manatee vocalizations shows great promise.
Adaptative Schur algorithm dedicated to underwater transient signal processing
Authors: Lopatka Maciej , Adam Olivier , Laplanche Christophe , Zarzycki Jan , Motsch Jean-François
Published: October 2013

The algorithm proposed by Lee and Morf [IEEE Transactions on Circuits and Systems 28(6) (1981)] which stems from the method defined by Schur [Operator Theory: Advances & Application, Vol. 18 (Birk-Verlag, 1986)] has acquired a new significance [Zarzycki, Journal of Multidimensional Systems & Signal Processing (Kluwer Academic, 2004)], due to its performances and particularly due to its applications in real time, made possible by the speed of processors available nowadays. Based on the innovations filter principle, Schur’s proposal models the signal by calculating reflection coefficients, describing entirely the second-order signal. The reflection coefficients can be simply transformed to the AR coefficients, from which one derives the time-frequency representation. We compare performances of this approach with other time-frequency representations commonly used in the signal processing (spectrogram, AR, wavelet transform); we subsequently present the results obtained for transitory underwater acoustic signals, which our laboratory is investigating. The Lee and Morf algorithm offers an excellent tracking of the signal’s characteristics and allows us to systematically detect transitory signals. This is particularly pertinent to segmentation problems relating to the application of underwater acoustics. The robustness of the Schur detector and a resolution of the Schur time-frequency representation support the resurgence of the Schur algorithm.
Nonlinear frequency dependence of the effective seabottom acoustic attenuation from low-frequency field measurements in shallow water
Authors: Zhou Ji-Xun , Zhang Xue-Zhen
Published: October 2013

Hamilton’s seabed geo-acoustic model, which is widely accepted, predicts that the attenuation of sound in marine sediments increases linearly with frequency over the full frequency range of interest in ocean acoustics (a few hertz to megahertz). However, Biot-Stoll’s physics-based seabed geo-acoustic model predicts that the bottom attenuation should exhibit non-linear frequency dependence, particularly in sandy bottoms. Since the publication of previous papers [Zhou, J. Acoust. Soc. Am. 78, 1003–1009 (1985); Kibblewhite, ibid. 86, 716–738 (1989)], more low-frequency field data, collected from different coastal zones around the world, have shown inconsistencies with the often-used linear frequency dependence. This paper attempts to support the non-linear frequency dependence of sea bottom attenuation through a review of shallow-water acoustic field measurements, with a special emphasis on the 50–1000 Hz frequency range. The relevant measurements include bottom reflection loss, sound transmission loss, dispersion analysis, vertical coherence of both propagation and reverberation, normal-mode spatial filtering, and optimum frequency and transition range of sound propagation. A non-linear frequency dependence of equivalent bottom acoustic attenuation, derived from these measurements, will be introduced. [Work supported by ONR and NNSF of China.]
Overview of SAX99 and SAX04 measurements of sediment sound speed and attenuation
Authors: Thorsos Eric I. , Williams Kevin L. , Jackson Darrell R. , Tang Dajun
Published: October 2013

During SAX99 (for sediment acoustics experiment—1999) the sediment sound speed (125 Hz to 400 kHz) and attenuation (2.5 to 400 kHz) in sandy sediments were measured by a variety of techniques. The SAX99 site was 2 km from shore on the Florida Panhandle near Fort Walton Beach in water of 18–19 m depth. SAX04 was held in the fall of 2004 at a site close to the SAX99 site, about 1 km from shore in water of 17 m depth. The sediment sound speed and attenuation were again measured over a broad frequency range by multiple techniques, with even more attention paid to the low frequency band from 1–10 kHz. The results and corresponding uncertainties from SAX99 will be reviewed, and the consistency with Biot model predictions and alternative models (e.g., Buckingham’s model) will be discussed. An overview will then be presented of the recently completed SAX04 measurement program on sediment sound speed and attenuation. [Work supported by ONR.]
Frequency dependence of posterior probability distributions for Biot parameters
Authors: Neilsen Tracianne B. , Isakson Marcia , Xu Buye
Published: October 2013

The Biot-Stoll poro-elastic model for sediments is parameterized by 13 properties. Initial investigations indicate that the individual Biot parameters influence reflection loss differently depending on the frequency range of interest. A more extensive study of the frequency dependence of the parameter sensitivities is performed by computing posterior probability distributions (PPDs) [S. E. Dosso, J. Acoust. Soc. Am. 111, 129–142 (2002)] to determine which parameters most influence reflection loss for each frequency decade from 100 Hz to 1 MHz. The sampling for the PPDs is based on the least-squares error between simulated reflection coefficient data and values modeled with the reflection module of OASES. [H. Schmidt, ‘‘OASES Version 2.1 User Guide and Reference Manual,’’ Department of Ocean Engineering, Massachusetts Institute of Technology, 1997.] The PPDs provide a quantitative value of the uncertainty in the optimum parameter estimates obtained by sampling or inversion techniques. A good value of the uncertainty is critical if one wants to use parameter estimates obtained with data from one frequency range to predict acoustic response for a different frequency range. [Work supported by the ONR.]
Sediment layer perturbation influences on the frequency dependence of effective bottom attenuation
Authors: Nickila James D. , Smith Kevin B. , Potty Gopu
Published: October 2013

Over the past several years, concern has grown over the appropriateness of bottom attenuation models that assume a linear frequency dependence. Empirical analyses of experimental data have suggested power law dependence with frequency exponents as high as 1.7 and above, but with large variability between geographic regions. [Zhou et al., J. Acoust. Soc. Am. 82, 287–292 (1987).] The fundamental cause of this dependence is unknown. In this study, we investigate the effect of perturbations (both random and deterministic) in the sediment layer on the effective attenuation factor for a range of frequencies. A parabolic equation (PE) model is used to generate the acoustic field for a given environmental realization. The pressure field is decomposed using a normal mode expansion and an effective attenuation factor is calculated. Regression is performed on the resulting attenuation vs. frequency curve, with particular emphasis placed on testing for non-linearity.
Here and there, near and far: How proximity and separation affect scattering in concert halls
Authors: Lee James B.
Published: October 2013

Classical theory of scattering deals with plane waves, waves which are so far from their source that they form straight fronts of sound, with pressure amplitude and particle velocity exactly in phase. If such waves are much larger than objects they encounter inverse fourth power (Rayleigh) scattering obtains; if the waves are about the same size as the objects resonant (Mie) scattering occurs; if waves are much shorter than the objects specular (Ufimtsev) scattering is the rule. These all affect sound in the far field. But if sources are closer than a wavelength to objects their waves encounter the plane approximation is not valid; pressure amplitude and particle velocity are not in phase, so resonance-like phenomena occur. These occur on stages of concert halls: bass instruments producing waves 2 m or longer always are close to the floor; some, like tympani and viols, can be close to vertical surfaces too. This sort of scat-tering enhances fundamentals of notes with respect to the overtones, strongly affecting the timbre of such instruments.
Diagnosing scattering with the Wigner distribution
Authors: Lee James B.
Published: October 2013

The Wigner distribution resolves the power of a signal in both the time domain and the frequency domain. It also is a complete representation because it displays the relative phases of a signal’s components as cross-products between them. This means that if one records the time-series of an impulse response in a room and computes a Wigner distribution from it, the kind of scattering, predominantly resonant or predominantly specular, is readily apparent, because the phase response of each is radically different. Specular scattering preserves the relative phases among components comprising the initial impulse and so preserves the impulse itself; resonant scattering randomizes the phases among components and so converts an impulse into a wide band of frequencies spread smoothly in time. Thus specular scattering tends to promote echoes and resonant scattering tends to promote diffusion. Graphic examples of each are given in the literature.
A comparison of partially specular radiosity and ray tracing for room acoustics modeling
Authors: Beamer C. Walter , Muehleisen Ralph T.
Published: October 2013

Partially specular (PS) radiosity is an extended form of the general radiosity method. Acoustic radiosity is a form of bulk transfer of radiant acoustic energy. This bulk transfer is accomplished through a system of energy balance equations that relate the bulk energy transfer of each surface in the system to all other surfaces in the system. Until now acoustic radiosity has been limited to modeling only diffuse surface reflection. The new PS acoustic radiosity method can model all real surface types, diffuse, specular and everything in between. PS acoustic radiosity also models all real source types and distributions, not just point sources. The results of the PS acoustic radiosity method are compared to those of well known ray tracing programs. [Work supported by NSF.]
Imaging for understanding speech communication: Advances and challenges
Authors: Narayanan Shrikanth
Published: October 2013

Research in speech communication has relied on a variety of instrumentation methods to illuminate details of speech production and perception. One longstanding challenge has been the ability to examine real-time changes in the shaping of the vocal tract; a goal that has been furthered by imaging techniques such as ultrasound, movement tracking, and magnetic resonance imaging. The spatial and temporal resolution afforded by these techniques, however, has limited the scope of the investigations that could be carried out. In this talk, we focus on some recent advances in magnetic resonance imaging that allow us to perform near real-time investigations on the dynamics of vocal tract shaping during speech. Examples include Demolin et al. (2000) (4–5 images/second, ultra-fast turbo spin echo) and Mady et al. (2001,2002) (8 images/second, T1 fast gradient echo). A recent study by Narayanan et al. (2004) that used a spiral readout scheme to accelerate image acquisition has allowed for image reconstruction rates of 24 images/second. While these developments offer exciting prospects, a number of challenges lie ahead, including: (1) improving image acquisition protocols, hardware for enhancing signal-to-noise ratio, and optimizing spatial sampling; (2) acquiring quality synchronized audio; and (3) analyzing and modeling image data including cross-modality registration. [Work supported by NIH and NSF.]
Inverting for sandy sediment sound speed in very shallow water using boat noise
Authors: Tang Dajun
Published: October 2013

Small boat propeller noise was recorded on a single hydrophone in very shallow water for the purpose of estimating sediment sound speed. The experiment was conducted near shore in water depth between 2 and 10 m. The sediment consisted of uniform sand. The lone hydrophone was moored 2 m above the bottom at 6 m depth. A small boat traveling at constant speed was used as the sound source, and ran both parallel and perpendicular to shore. Thus, both the range independent waveguide case and wedge shaped waveguide case could be investigated. The source tracks were recorded by using a GPS recorder on the boat. Water depth in the entire area was measured, as was the sound speed profile at the receiver. The processed date sets resulted in interference patterns in range-frequency plots. Aided by numerical simulations, sediment sound speed can be estimated over the frequency range of 500–4500 Hz. [Work supported by the U.S. Office of Naval Research.]
Longitudinal wave dispersion and attenuation in a two phase granular material
Authors: Tavossi Hasson
Published: October 2013

Longitudinal elastic wave-velocity and attenuation in a two phase granular material are investigated, in the cases of a random arrangement of grains in contact with each other, surrounded by water or air. The velocity dispersion and attenuation of a longitudinal wave are measured experimentally, at low and high frequencies and are analyzed in light of a modified Biot theory. The results of these analyses on wave velocity and attenuation are expressed as a function of frequency, grain size, porosity, viscosity of the fluid phase, as well as elastic moduli and densities of the solid and fluid phases. It is shown that longitudinal wave velocity in such a material decreases with grain size and frequency at high frequencies. Results obtained by increasing the grain size resemble those measured by increasing the frequency. Wave attenuation is expressed as a function of frequency, porosity, grain size and fluid viscosity. Theoretical results are compared with the experimental findings on the wave velocity and attenuation.
Barnum Hall—The continuing renovation of a Streamline Moderne theater
Authors: Shaw Neil A. , Koslow Kenneth , Sedillos Jean , Mobley Jim
Published: October 2013

Barnum Hall, built by the WPA in 1937 and located on the campus of Santa Monica High School, was the first Santa Monica Civic Auditorium. After 60 years it was closed for renovations. The building has historic significance, which placed some limitation on the renovation design as to what could be done. Balancing the interests of the various stakeholders—the Santa Monica-Malibu Unified School District, the City of Santa Monica Landmarks Commission, fund raisers, high school faculty, and community members, among others—impacted the design and construction process. The first phase included expanding and modernizing the stage house and surrounding support areas. Phase II of the work was concerned with mitigating the orchestra level rear wall reflections, modifying the balcony nose profile, adding an orchestra pit lift, the purchase of a custom acoustical orchestra shell, and improving creature comfort (air conditioning) and amenities (improving restrooms, creating a backstage area, and refurbishing 75% of the theater seats). A study of several sidewall shaping schemes were then analyzed to determine if the improvement in the level of envelopmental sound warranted the cost. Phase III will see the installation of a modern sound reinforcement system and refurbishing the last section seats.
Returning an acoustic legend to its original glory (and then some)
Authors: Pfeiffer Scott
Published: October 2013

Hill Auditorium at the University of Michigan broke all of the rules of modern day acoustic design, while still providing a tremendously rewarding experience for large audiences. The combination of diverse and intriguing programming by the University Music Society and the University Music Department, including the use of the Frieze Memorial Organ, provides tremendous opportunities for the community of Ann Arbor, MI to access great performances. The restoration project included air conditioning, elevators, and new sound systems. Additionally, improvements were made with respect to seating; specifically, sightlines, accessible seating, and under balcony seating were improved upon. This restoration project provided opportunities to revitalize the already famous acoustics without sacrificing unique and characteristic qualities of the hall. By drawing on the original architects, Albert Kahn Associates, utilizing the expertise of Quinn Evans Architects, as well as through the help of Gary Steffy Lighting, Fisher Dachs Associates, and many others in design and construction, (most notably a great client in the University of Michigan), the project secured the 2004 AIA National Honor Award.
The feasibility of noise and reverberation control for good acoustics in classrooms
Authors: Brooks Bennett M.
Published: October 2013

The acoustics of classrooms has been the subject of increasing scrutiny, as good speech intelligibility is recognized as an essential feature of an effective educational environment. There is consensus on the need for low levels of background noise and reverberation. Acceptable values for these parameters have been published as a standard [ANSI S12.60-2002]. The technical feasibility of achieving these goals is well established. In the US, few jurisdictions require that classrooms meet acoustical standards. The limits to constructing acoustically adequate classrooms are primarily economic. Perception and understanding of the issue are also important, as those who specify and pay for classrooms, school boards and taxpayers, are not those directly served in them, students. As the direct customers and their immediate providers, teachers, have little power, feasibility depends on competing priorities set by interested non-users. Therefore, advocates must sell the cost/benefits to the decision makers. Widely scattered data are available on costs as a percentage of the total school building project. However, detailed cost data for individual mechanical system components that meet noise standards are scarce. Also, long-term economic paybacks must be quantified. Available cost data and areas needing better definition are summarized here.
Low impact renovations with high performance sound insulation
Authors: Roy Kenneth P. , Browne Sean D.
Published: October 2013

Architectural renovations, although often driven by visual objectives, are a good opportunity to pursue acoustical interventions involving both sound intrusions into a space, and sound quality of the acoustic environment within the space. A high priority is to keep the construction impact low as it affects both project cost and schedule. Obviously, if the architectural intervention can be accomplished using external measures such as the addition of added elements to the existing structure, then that would be a definite advantage. Test data will be presented for the application of sound insulating/absorbing panels to existing drywall structures. It will be shown that such an overlay panel can add sufficient damping to result in essentially ‘‘mass law’’ performance of the system. This will not only result in STC improvement, but more importantly will result in even higher voice insulation between spaces. This effect will be auralized for comparison listening purposes. If the added panel is also of a sound absorbing nature, such as those used in the tested cases, then they will also have the effect of adding to the receiving room sound performance.
Wesley Nyborg and bioacoustics at the University of Vermont
Authors: Wu Junru
Published: October 2013

Wes Nyborg came to UVM in 1960. Burlington, Vermont has become his home. He did his most pioneering research in microstreaming, acoustic radiation pressure and bioeffects of ultrasound at UVM. His research was continuously supported over 20 years by NIH. In 1987, after receiving Ph.D. in Physics and working with Isadore Rudnick for two years as a postdoc in the field of nonlinear physics, I joined the faculty of the University of Vermont as an assistant professor. Dr. Nyborg just retired from teaching in 1986. He was the person who convinced me to start research in the field of biomedical ultrasound. This presentation will review the development and achievement of bioacoustics at UVM and will also introduce him as a mentor, friend, colleague and collaborator.
Cavitation inception on micro-particles: Possible drug carriers?
Authors: Arora Manish , Borkent Bram , Ohl Claus-Dieter
Published: October 2013

Hydrophobic particles are known to act as cavitation nuclei when they are exposed to a sufficient tensile wave. Yet, the dynamics of cavitation inception from particles, the growth of the bubble and the separation from the particle has only recently been observed. [M. Arora, C. D. Ohl, and K. A. Moerch, Phys. Rev. Lett. 92, 174501 (2004)] In this presentation, high-speed photography of the remarkable dynamics is presented together with a modeling effort using a force balance approach. One of the results is that particles are accelerated to velocities up to 10 m/s and detach from the bubble. It was proposed, that micro-particles might act as drug carriers which can be activated by a tensile wave and accelerate into tissue or cells. In an effort to explore this possibility experiments on the cavitation inception ability on various types of micro-particles have been conducted in a reproducible way. Cavitation inception is initiated with a single cycle tensile wave and recorded with a camera. The number of cavitation bubbles decreases from shot-to-shot, which can be explained with one-time trigger-able nucleation sites on the particles.
Spatial correlations in fluctuations induced by long-range propagation of sound in the atmosphere
Authors: Talmadge Carrick L. , Dravida Shantharam , Gilbert Kenneth E. , Waxler Roger
Published: October 2013

Amplitude and phase fluctuations associated with sound propagating over long distances are well known to increase rapidly with distance [e.g., Wilson, Noble, and Coleman, J. Atmos. Sci. 60, 2473 (2003)]. This increase in the fluctuation level is usually given as an argument that the sound source becomes temporally incoherent after propagating large distances, making signal processing techniques that rely on the temporal coherence of the signal impracticable for single microphone measurements. Results are presented from a series of experiments designed to measure the spatial coherence of sound in both day- and nighttime conditions. In these experiments, 24-element horizontal and 8-element vertical arrays were used to measure the coherence of sound sources over the frequency range 30–200 Hz (horizontal array) and 100–500 Hz (vertical array). In many of these experiments, surprisingly large spatial coherences in the source strength were observed. These results suggest that array measurements may allow us to compensate for the poor temporal coherence of the signals for long-range propagated sound. We will also discuss the different sources of the observed fluctuations in the sound level and phases for daytime versus nighttime conditions. These sources include atmospheric turbulence, changes in the nocturnal boundary layer height and nocturnal gravity waves.
Prediction of aerodynamically generated sound via 3D particle velocity measurements
Authors: Wu Sean , Kumar Aditya , Ni Zhi , de Bree Hans-Elias
Published: October 2013

It has been shown [Wu and Hu, J. Acoust. Soc. Am. 103, 1763–1774 (1998)] that acoustic radiation from a vibrating object can be calculated directly by an Alternate Integral-formulation Method (AIM), once the particle velocity distribution over a hypothetical surface enclosing this object is specified. This concept is extended here to prediction of aerodynamically generated sound. The particle velocity distribution on a hypothetical enclosure is measured by a fully integrated sound pressure-velocity (p-u) probe. This novel p-u sensor combines a MEMS particle velocity sensor and miniature pressure transducer, which allows for measurements of the acoustic pressure and particle velocity at a single point simultaneously. It is simple and easy to use and is suitable for both narrow and broadband sound measurements. This p-u probe is employed to measure the particle velocity field generated by a typical hairdryer. Measurements thus obtained are taken as input to AIM to predict the radiated acoustic pressure field. Experiments are conducted inside an anechoic chamber at the Acoustics, Vibration, and Noise Control Laboratory at Wayne State Uni- versity. The predicted acoustic pressures are then compared with those measured at the same locations by microphones. Satisfactory agreements are obtained at all frequencies.
A comparison of conventional and metal foam windscreens
Authors: Becker Gunnar R. , Hermstruewer Guenther H. , Knoetsch Rainer
Published: October 2013

In outdoor applications wind induced noise reduces the signal quality significantly. Conventional windscreens made of polyurethane (PU) foam are widely used to reduce this noise. However under harsh environmental conditions such as high temperatures, exposition to UV radiation, etc., PU may suffer. An alternative may be the usage of metal foams instead of PU foams. Spherical windscreens made of open-pored metal foam with dimensions close to commercial ones and different pore distributions have been manufactured by m-pore and were tested under different wind conditions. Comparative measurements between both conventional PU- and metal foam windscreens indicated that the reduction of wind induced noise is almost the same. A reduction of the receiver level due to the windscreens was not observed. Measurements and test results will be presented. [Work supported by m-pore.]
Level effects in amplitude modulation tuning
Authors: Wojtczak Magdalena , Viemeister Neal F.
Published: October 2013

Psychophysical experiments on amplitude-modulation (AM) masking suggest the existence of channels selectively sensitive to different ranges of modulation rates. This study investigates whether tuning depends on carrier level. Masking of a 40-Hz signal AM was measured as a function of the masker-AM rate selected from the range between 4 and 256 Hz, for Gaussian-noise and 5.5-kHz carriers. For the noise carrier, similar patterns were observed at two different spectrum levels (25 and 40 dB SPL), leading to similar estimates of the modulation-filter bandwidths. For the tonal carrier, however, tuning in AM masking varied considerably across levels. At the lowest level tested (40 dB SPL), the patterns were very broad and highly asymmetric. The patterns became more similar across carrier levels when a highpass noise was presented with the carrier. The noise limited the use of spread of excitation and thus, raised thresholds for the unmasked signal detection. The data suggest that the AM selectivity is strongly affected by the detection threshold for the unmasked AM. [Work supported by NIH grants DC00683 and DC006804.]
Spectral integration and mutliple looks
Authors: Lutfi Robert
Published: October 2013

A fundamental property of hearing is that signals become more detectable as their bandwidth is increased. The rate at which detection improves is reasonably well predicted by models that assume integration of energy at the output of a single auditory filter roughly matched in bandwidth to the signal. This paper tests an alternative account in which detection is mediated by not one but several independent auditory filters whose outputs are combined (multiple-looks model). Listeners detected an increment in the level of a multitone complex whose bandwidth was increased by adding tones at successively higher and lower frequencies. In different conditions the frequencies were fixed (F) or were perturbed at random from trial to trial with the perturbation being the same (PS) or different (PD) for each frequency. The multiple-looks model predicts performance should improve with bandwidth at a faster rate for PD and at a slower rate for PS compared to F; this due to differences in the shared variance in the output of separate auditory filters. The single filter model predicts little effect of frequency perturbation in either case. Individual differences in the results provided partial support for both models. [Work supported by NIDCD.]
The advantage of knowing where to listen
Authors: Kidd Gerald , Arbogast Tanya L. , Mason Christine R. , Gallun Frederick J.
Published: October 2013

This study examined the importance of a priori knowledge about the location of a target in a multitalker environment. On each trial, three equal-level sentences from the Coordinate Response Measure test were presented from different loudspeakers separated by 60° azimuth. The sentences—target and 2 maskers—had the structure ‘‘Ready [callsign] go to [color] [number] now.’’ The task was to repeat the color and number associated with a specific callsign. The target location was chosen among the 3 loudspeakers on every trial. The main experimental variables were the probability of occurrence of the target at each speaker location and whether the listener was provided with the callsign of the target before or after stimulus presentation. Performance ranged from near perfect when the target location was completely certain to about 33% correct when the location was random and the callsign was not known in advance. When target location was random, performance improved from about 33% to 70% correct when the callsign was known in advance. Overall, these results support the view that knowing where to focus attention provides a great advantage in speech recognition in complex and uncertain environments. [Supported by NIH/NIDCD.]
Development of backward masking in elementary school children
Authors: Zettler Cynthia M. , Clarkson Marsha G. , Sevcik Rose A. , Morris Robin D.
Published: October 2013

Previous research on backward masking (BM) suggests that the ability develops slowly across childhood. When a spectral notch is placed in a noise masker, thresholds improve due to a decrease in masker energy at the frequency of the signal. To further clarify the developmental course of BM thresholds for BM and backward notched-noise (BM-N), conditions were measured in 81 children ranging in age from seven to ten years. BM stimuli consisted of a 20-ms, 1000-Hz tone presented 20 ms prior to a 300-ms, 600–1400 Hz bandpass noise. BM-N stimuli consisted of a 1000-Hz tone presented 20 ms prior to the onset of a 300-ms, 400–1600 Hz bandpass noise with a spectral notch between 800 and 1200 Hz. Multivariate analysis of variance indicated a significant difference among age groups for the BM condition (F(3,77)=3.63, p<.05), but not for the BM-N condition. Thresholds generally decreased with increasing age in the BM condition (age seven 87.86 dB; eight 81.36 dB; nine 75.31 dB, and ten 77.26 dB). Increased BM thresholds in younger children may indicate poorer processing efficiency, whereas the notched results suggest that frequency selectivity is relatively mature by age seven.
Development of a composite material concert harp soundboard to match the structural acoustic performance of a wooden soundboard
Authors: Royston Thomas J. , Carney Melinda J. , Preissner Curt , Roxworthy John
Published: October 2013

The replacement of a Sitka spruce grand concert harp soundboard with a carbon fiber-reinforced plastic soundboard could provide improved durability and long-term stability, helping to mitigate stresses relating to fluctuating temperature and humidity that are inherent in wooden instruments. This presentation outlines the development of a composite soundboard by a combined experimental and computational approach. Experimental modal analysis data was compared with the results from a computational finite-element model to find the effective material properties of the multi-layered laminate wooden soundboard, treating the veneer, soundboard and varnish as one material. With the effective wood material properties determined, a composite test section was designed and fabricated based on specific matching criteria, duplicating the behavior of the wood with the composite laminate. The experimental natural frequencies and mode order of the composite test section closely matched the experimental results of the wood section within a 10% difference. Given these results, the method was then applied to design and manufacture a full composite soundboard. Various finite element models were created to develop the most practical design while sufficiently matching the wood soundboard properties. Issues regarding the implementation of the composite soundboard were also investigated.
Computational fluid dynamics simulation of a sibilant
Authors: Nozaki Kazunori , Akiyama Toyokazu , Shimojo Shinji , Maeda Shingo , Kaishima Takeshi , Tamagawa Hiroo , Maeda Yoshinobu
Published: October 2013

It is well known that a sibilant is generated around the anterior teeth and the frontal part of palate. However, there is no study that the sibilant sound source is detected and visualized. Dentists often need to fabricate the prostheses including the anterior teeth and the palate. It would be useful if the critical part of the prostheses on the generation of sibilant could be detected before the fabrication and treatment. In this present study, Computational Fluid Dynamics simulation was performed in order to examine the oral air flow on pronouncing sibilant. Moreover, Powell sound source around the anterior teeth was detected and visualized by combining Computational Fluid Dynamics simulation and Computational Acoustical Analysis. As a result of this study, dentists can obtain the clinical criteria of the prosthetic treatment with considering sibilant.
Stabilization techniques for ultrasound imaging of speech articulations
Authors: Davidson Lisa , De Decker Paul
Published: October 2013

One challenge for the ultrasound imaging of the tongue during connected speech is stabilization of both speakers heads and the ultrasound transducer. To accurately analyze tongue shapes, researchers must ensure that differences among images result from changes in tongue shape, not head or transducer movement. In this validation study, we present an inexpensive, space-saving technique for stabilizing the head and transducer during the collection of ultrasound images in the laboratory. Four speakers were video-recorded producing 5 blocks of 19 sentences each. The speakers’ heads were immobilized with a moldable head stabilizer (Comfort Company, model ♯HSM) affixed to a wall while the transducer was held by a microphone stand. Markers were attached to points on the speakers’ faces and the transducer. Custom-written MATLAB software was used to find the center of the markers for every 10th frame of the recordings. Results indicate that the transducer does not move, and head movement beyond the measurement error of 1 mm is confined to the first block, while speakers are adjusting to the equipment. As compared to other stabilization techniques [Stone and Davis, J. Acoust. Soc. Am. 98, 3107–3112 (1995)], this method provides equivalent immobilization that is significantly less expensive and portable for fieldwork.
Experimental reproduction of random pressure fields in laboratory conditions
Authors: Bravo Teresa M. , Maury Cedric
Published: October 2013

The design and the physical implementation of an experimental set-up are discussed for the off-line reproduction of random wall-pressure fluctuations with given spatial correlation characteristics. This approach could provide a cost-effective laboratory method of both reducing the variability of low frequency sound transmission measurements as well as measuring the boundary layer noise transmitted through aircraft fuselage structures. Three different types of random excitations are considered, namely an acoustic diffuse field, a turbulent boundary layer excitation and an acoustic progressive wave at grazing incidence angle. The corresponding excitations are generated in a semi-anechoic chamber using a near-field array of 4×4 loudspeakers optimally driven and located above a set of 13×16 microphones. The microphones are positioned a short distance apart from an aluminum test panel. The optimal driving signals are determined from acoustic transfer functions measurements between the grid of microphones and the array of loudspeakers. Given this number of loudspeakers, a reasonable reproduction of the boundary-layer excitation is achieved up to about 200 Hz and a good approximation of both the acoustic diffuse field and the progressive wave is obtained over the frequency range of interest, i.e. up to about 700 Hz. [Work supported by ANVAR.]
Influence of internal wave fluctuations on acoustic underwater propagation
Authors: Andreeva Tatiana A. , Durgin William W. , Wojcik Stefanie E.
Published: October 2013

The work presents a ray acoustic based analysis of the effect of ocean internal waves and its fluctuations on acoustic wave propagation. In the present work, it is shown that consideration of only perfect internal waves simplifies the real problem, disregarding the fluctuations of internal waves. The focus of the paper is to study numerically the influence of internal wave fluctuations and the role of an initial ray angle onto underwater acoustic propagation. In the present formulation the eikonal equation is considered in the form of a second order, nonlinear ordinary differential equation with harmonic excitation due to internal wave. The harmonic excitation is taken imperfect, i.e., with a random phase modulation due to Gaussian white noise. The amplitude and wavelength of the acoustic waves are used as the principle signal characteristics in bifurcation analysis. The regions of instability are identified using the bifurcation and phase diagrams. The effect of internal waves phase modulation is demonstrated by means of comparison of the numerical data obtained in the present work with data, obtained perfect internal wave. The preliminary analysis shows very strong dependence of acoustic propagation on intensity of fluctuations.