bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of nanometric ultrasound contrast agents with a liquid perfluorocarbon core
Authors: Astafyeva Ksenia , Conoir Jean-Marc , Guédra Matthieu , Fattal Elias , Pepin Christine , Polidori Ange , Taulier Nicolas , Thomas Jean-Louis , Tsapis Nicolas , Valier-Brasier Tony , Urbach Wladimir
Published: November 2013

In this work, we propose a new type of nanometric ultrasound contrast agents (nUCA) with a liquid core and we model their acoustic propagation through their dilute solutions. These capsules have a shell made of a biocompatible polymer or fluorinated surfactants and a liquid perfluorocarbon core to undergo a high lifetime. The capsules are small enough (from 100 nm to 1 μm) to pass through the tumor endothelium, and they remain stable in vitro for several months. Ultrasound attenuation and speed of sound measurements through dilute suspensions of nUCA were carried out from 3 to 90 MHz at various temperatures and concentrations. The acoustic propagation was modeled by combining (i) a dilatational mode taking into account the radial oscillations of the capsules, and (ii) a translational mode of oscillations induced by viscoinertial interaction with the continuous phase. The model makes possible to fit with good accuracy the experiments using values compatible with literature data. Moreover, it reveals information about unknown parameters of the shell: for instance, the viscoelastic shell has to be described as a Maxwell rheological medium. [This work was supported by Emergence-UPMC program.]
Use of Bessel side lobe modulation of frequency modulated pulse bearing estimation
Authors: Walsh Kenneth M.
Published: November 2013

The beam pattern of a circular transducer is a set of frequency dependent Bessel functions. By using a broad band FM pulse and a 1–3 composite transducer, it appears that the modulation in amplitude and phase due to a reception of the high frequency components can be used to estimate the echo's angle off the transducer axis. The 1–3 composite transducer has a simple amplitude and phase structure.
Modeling of bio-inspired broadband sonar for high-resolution angular imaging
Authors: Gaudette Jason E. , Simmons James A.
Published: November 2013

Echolocating mammals perceive images of targets with hyper-resolution and navigate seamlessly through obstacles in complex acoustic environments. The biological solution to imaging with sound is vastly different from man-made sonar. The most prominent difference is that instead of imaging with narrow beams, bats ensonify a large spatial region and exploit broadband echo information to acoustically focus with about one degree of angular resolution. Angular localization may therefore be redefined as a spectral pattern matching problem. By imaging with wider beams, this remarkable performance requires only a single broadband transmitter and two receive elements. Our computational modeling work has led to new insight into the salient spatial information encoded by the bat’s auditory system. Although theoretically not required, spatial localization performance increases with the aid of highly complex baffle structures such as those found in biological sonar. Replicating these bio-inspired baffle structures and acoustic processing techniques in man-made systems can reduce sonar array aperture requirements by a factor of 100 or more for a variety of both aerial and underwater acoustic sensing applications. Recent modeling results are presented along with progress toward the design of a compact bio-inspired sonar system for high-resolution imaging. [Work supported by ONR and NUWC Newport.]
LinnStrument and other new expressive musical controllers
Authors: Linn Roger
Published: November 2013

Roger Linn will demonstrate his LinnStrument, a controller for musical performance that captures three dimensions of movement for each touch, polyphonically, in order to provide more expressive control of software music synthesis. In addition, he will show videos of other similar new instruments and compare the unique approaches taken by each designer.
Grafting acoustic instruments and signal processing: Creative control and augmented expressivity
Authors: Overholt Dan
Published: November 2013

In this study, work is presented on a hybrid acoustic/electric violin. The instrument has embedded processing that provides real-time simulation of acoustic body models using DSP techniques able to gradually transform a given body model into another, including extrapolations beyond the models to explore interesting new timbres. Models can include everything from various violin bodies to guitars, sitars with their sympathetic strings, and even physically impossible acoustic bodies. The development also presents several practical approaches to sensor augmentation and gestural playing techniques that can be applied to bowed-string and other acoustic instruments, in order to provide immediate creative control over the possibilities offered by DSP. The study has focused on augmenting the expressivity of the violin toward finding novel timbral possibilities, rather than a goal of simulating prior acoustic violins with high fidelity. The opportunity to control a virtually malleable body while playing, i.e., a model that changes reverberant resonances in response to player input, results in interesting audio effects. Other common audio effects can also be employed and simultaneously controlled via the musician’s movements. For example, gestural tilting of the instrument is tracked via an embedded Inertial Measurement Unit (IMU), which can be assigned to alter parameters such as the wet/dry mix of an octave-doubler or other effect, further augmenting the expressivity of the player.
Saxophone fingering identification
Authors: Smyth Tamara , Rouhipour Marjan
Published: November 2013

The focus of this work is to identify the tonehole configuration or “fingering'' applied by a player during performance, using only the signal recorded at the bell. Because of a player can use alternate fingerings/overblowing to produce a given frequency, detecting the sounding pitch only reduces the possible candidates—it does not produce a unique result. Several recordings of a professional saxophonist playing notes using all fingerings are considered, and several higher level features are explored for distinguishing between a fundamental and an overblown note. In the latter case, it is observed that during the attack portion of the note, the spectral centroid is usually lower, there is greater inharmonicity and increased pitch instability. Combining these heuristics with the detection of subharmonics has yielded excellent results in detecting overblown notes. With the possible fingerings being greatly reduced by this preprocessing, more computationally expensive statistical methods may be employed for a more accurate estimation of the actual fingering applied. To this end, the recorded sound is calibrated to that produced by a reed model coupled to a waveguide that is informed by an acoustic measurement of the player's saxophone configured with each usable fingering.
The Stingray embedded acoustic instrument
Authors: Berdahl Edgar J.
Published: November 2013

Many traditional acoustic musical instruments are convenient to use: a performer picks one up, provides an energetic excitation, and the resulting sound radiates immediately. No wires, protocols, or software updates are ever required. The same cannot be said for the vast majority of prior digital musical instruments. The present work addresses how to endow a digital musical instrument with the convenience, look, feel, and personality of a traditional acoustic musical instrument via enclosure prototyping techniques, audio amplification, and embedded computation. For example, the Stingray is an embedded acoustic instrument. Although its battery needs to be occasionally charged, it otherwise can give the impression of a traditional acoustic musical instrument. The control inputs for the Stingray include a piano keyboard and force-feedback motorized faders. The faders allow the performer to interact expressively with the sound, while the piano keyboard enables the precise selection of notes. If desired, the Stingray can be programmed using physical models, including models of hypothetical acoustic instruments that would be infeasible to build physically. In this configuration, the Stingray expressively transforms the performer's gestures into radiated sound in an energy-conserving manner.
Far-field acoustic modeling of rocket noise to determine community impacts
Authors: James Michael M. , Salton Alexandria R. , Downing Micah
Published: November 2013

The emerging commercial space market is generating interest in commercial launch site (“spaceport”) development around the United States. FAA regulations require all new spaceports to acquire a launch site operator’s license, which is considered a Federal action subject to environmental review. Potential noise impacts are evaluated based on FAA Order 1050.1E, Change 1, Environmental Impacts: Policies and procedures, which include the assessment of DNL and may be supplemented with additional acoustical metrics. These supplemental metrics may range from speech interference to structural damage impacts. Extensive studies and research have examined the appropriateness of these metrics in relation to aircraft operations. However, the differences between these acoustic sources and operational modes stress the need for computer models and impact criteria specific to launch vehicles. Further measurements and research are needed to improve rocket source characterization, long-range sound propagation of high amplitude waveforms through complex atmosphere, and environmental and community impacts. The evolving nature of the regulatory environment surrounding rocket noise warrants a renewed focus on appropriate noise modeling and impact criteria to determine potential conflicts with launch noise.
Evaluation of Japanese current primary launch vehicle liftoff acoustic environment change due to launch pad facility modifications
Authors: Ashida Hiroki , Hirai Makoto , Terashima Keita , Ujino Takumi
Published: November 2013

H-IIA, Japanese primary launch vehicle, has been successfully launched 21 flights with a success rate of 95.4%. During 12 years of its operational phase, extensive acoustic measurements on the vehicle and on the ground have been conducted to refine conventional prediction methods and to evaluate the effect of vehicle/pad configuration changes. In this presentation, the evaluation of the effects of major pad configuration modification on H-IIA liftoff acoustic environment is presented. The effect of water injection is also evaluated.
Intensity-based approach to characterize near-field acoustic environments of space flight vehicles
Authors: James Michael M. , Salton Alexandria R. , Gee Kent L. , Neilsen Tracianne B.
Published: November 2013

An intensity-based measurement probe has been developed to measure the magnitude, directivity, and spectral content of near-field rocket source noise. An array of the intensity-based measurement probes was deployed in a static test firing of the GEM-60 at Alliant Techsystems in Promontory, UT, in 2012. The probes were positioned along the shear layer of the rocket motor plume to enable a comparison of the resultant source characterization obtained via sound power type measurement approaches to traditional acoustic measurement methodologies. The measurement results demonstrate that the intensity-based probes advance the measurement and characterization of the near-field acoustic environment of rockets. Moreover, intensity-based acoustic data provides an important role in formulating more realistic sound source models, improving acoustic load estimations, and aiding in the development of the next-generation space flight vehicles via improved measurements of noise near the rocket plume.
On the resonance frequency of an ideal arbitrarily shaped bubble
Authors: Spratt Kyle S. , Lee Kevin M. , Wilson Preston S. , Wochner Mark S.
Published: November 2013

Large encapsulated bubbles have recently been described for use in abating low-frequency anthropogenic underwater noise [J. Acoust. Soc. Am. 130, 3325–3332 (2011)], and the use of encapsulation allows for the possibility of bubbles that are nonspherical in their equilibrium state. For the purpose of more accurately determining such bubbles’ resonance frequencies, a lumped-element model of the linear oscillation of an ideal, arbitrarily shaped gas bubble in an incompressible liquid is presented. The corresponding boundary-value problem required to predict the resonance frequency of the bubble is seen to be equivalent to a classic problem in electrostatics [J. Acoust. Soc. Am. 25, 536–537 (1953)]. Predictions made for the resonance frequency of prolate and oblate spheroidal bubbles using this model are tested against a finite-element model of the full acoustic scattering problem. Particular attention is then paid to the case of an ideal toroidal bubble of arbitrary thickness, and predictions made for the resonance frequency of such a bubble using the lumped-element approach are compared to a finite-element model of the full acoustic scattering problem as well as to existing approximate models for the dynamics of thin toroidal bubbles. [Work supported by AdBm Technologies, LLC and the ARL:UT McKinney Fellowship in Acoustics.]
Testing and extending the Woodworth model
Authors: Hartmann William M. , Aaronson Neil L.
Published: November 2013

The Woodworth model and formula for interaural time difference is frequently used as a standard in physiological and psychoacoustical studies of binaural hearing for humans and other animals. It is a frequency-independent, ray-tracing spherical head model that is expected to agree with an exact diffraction model in the high-frequency limit. The predictions by the Woodworth model for antipodal ears and for incident plane waves are compared with the predictions of the exact model as a function of frequency to quantify the discrepancy when the frequency is not high. In a second calculation, the Woodworth model is extended to arbitrary ear angles, both for plane-wave incidence and for finite point-source distance. This extended Woodworth model leads to different formulas in six different regions defined by ear angle and source distance. It is noted that the characteristic cusp in Woodworth's well-known function comes from ignoring the longer of the two paths around the head in circumstances when the longer path is actually important. This error can be readily corrected.
Minimum audible angle at the subjective front during listener’s active and passive head rotation
Authors: Suzuki Yôiti , Honda Akio , Ohba Kagesho , Sakamoto Shuichi , Iwaya Yukio
Published: November 2013

Listener’s head movement, particularly horizontal rotation, effectively improves sound localization acuity (Wallach, 1939; Thurlow, 1967; Kawaura, 1989). However, few findings have been obtained concerning sound localization during head rotation. In the present study, we directly investigated the minimum audible angle (MAA) at the front during horizontal rotation. A sound stimulus (30-ms noise burst) was presented from a loudspeaker of a circular array (r = 1.1 m), with a loudspeaker separation of 2.5 degrees. The listener, sitting at the center of the circle, was asked to answer whether the sound stimulus was presented from the left or right of the subjective front (2AFC). We designed three listening conditions, static, active rotation and passive rotation. In the static condition, listeners were asked to keep their heads still. For the active rotation condition, listeners were asked to rotate their heads. Meanwhile, for the passive rotation condition, listeners sitting on a revolving chair were rotated by an experimenter. In the latter two conditions, the test stimulus was triggered during head movement. Results showed the MAA to deteriorate significantly in the two rotation conditions. This implies that the improvements in sound localization due to head motion could be explained by the multiple-look model (Viemeister, 1991).
Difference of the perceived auditory space between walking and passive self-motion
Authors: Sakamoto Shuichi , Terashima Hideaki , Teramoto Wataru , Suzuki Yôiti , Gyoba Jiro
Published: November 2013

We are investigating how auditory space was represented during linear self-motion (Teramoto et al., 2013). Several studies have suggested that whether the listener's motion is active or passive affected sound localization (Hirahara et al., 2013). In the present study, therefore, we set up three conditions: active motion condition, passive motion condition, and no motion condition. In active motion condition, observers were walking straight ahead. In passive motion condition, observers were transported forward by a robotic wheelchair. During the self-motion, a short noise burst was presented from one of the loudspeakers which were aligned parallel to the traveling direction when the listener's coronal plane reached the location of one of the speakers (null point). The listeners indicated the direction in which the sound was perceived relative to their coronal plane (i.e., a two-alternative forced-choice task). The results of experiment showed that the sound position aligned with the subjective coronal plane was displaced compared with the null point. However, there was no significant difference between auditory space in active and passive motion conditions. This result suggests only action of the kinetic system during self-motion and planning and execution of voluntary movement would not affect perceived auditory space.
A long-overdue review of empirical uncertainties in the “fatigue” found through simultaneous dichotic loudness balance
Authors: Nizami Lance
Published: November 2013

SDLB uses equalization of the loudnesses of stimuli at the two ears (one stimulus intermittent, one constant) to measure the alleged “fatigue” over time of the loudness of the constant stimulus (Hood, 1950). Hood found 50 dB of “fatigue”, and SDLB remained influential for over a quarter-century. However, the interpretation of SDLB was long questioned; recently, a novel model uniting the physiology and the behavior emerged (Nizami 2012, Int. Soc. Psychophys., Ottawa, Canada), and others independently re-measured “fatigue”. Classically, the stimulus waveforms at the two ears were similar, sometimes identical, permitting two equalization techniques when the stimuli coincided in time: centering of the sound between the ears (lateralization), or matching the loudness contributions from each ear (loudness-matching). Further, “fatigue” was habitually expressed as across-listeners averages. But careful scrutiny reveals that (1) over the “fatiguing” duration, lateralization may give way to loudness-matching, (2) dedicated loudness-matching may nonetheless yield only half as much “fatigue” as lateralization, and (3) the standard deviation of “fatigue” can be half its mean value, such that some listeners would not have “fatigued.” In sum, the magnitude of “fatigue” is remarkably uncertain, and is likely to remain so until auditory physiology is compellingly integrated into explanations of SDLB.
Influence of measurement method and context of presentation on the loudness difference between increasing and decreasing intensity sounds
Authors: Ponsot Emmanuel , Susini Patrick , Meunier Sabine
Published: November 2013

Four experiments were conducted to assess the loudness of both increasing and decreasing intensity sounds using different methods and context of presentation as between-subjects factors. In Exp 1 and Exp 2, loudness was assessed directly by using magnitude estimation procedures, with increasing and decreasing sounds presented respectively either in the same block or in separate blocks. In the other two experiments, loudness was measured by the mean of pairwise comparisons. While increasing and decreasing sounds were compared with each other in Exp 3, they were compared respectively with constant-intensity sounds in Exp 4. Two-intervals, 2AFC interleaved-adaptive procedures were used to prevent from potential biases. As a result, very similar trends were observed in the four experiments. In particular, the loudness difference between increasing and decreasing sounds always felt within the same range: decreasing intensity sounds need to be about 3 dB louder that increasing sounds to be perceived with equal loudness. This study thus indicates that this loudness asymmetry actually corresponds to a true perceptual effect and is not due to any experimental bias, since a clear consistency across the results was found using different measurement methods and context of presentation.
On the learnability of auditory concepts
Authors: Vigo Ronaldo , Barcus Mikayla , Zhang Yu , Doan Charles
Published: November 2013

The field of categorization and concept learning research has been dominated by findings involving visual stimuli. Among these findings is the learning difficulty ordering of the family of category structures associated with visual categorical stimuli consisting of four objects defined over three dimensions. This ordering has been observed numerous times in several rigorous studies (Kruschke, 1992; Love et al., 2004; Nosofsky et al., 1994; Shepard et al., 1961; Vigo, 2011a, 2013a. 2013b) and has been influential in shaping current theories of conceptual behavior. In recent work, we have freed the field from this visual bias by examining the learnability of auditory categorical stimuli that are instances of the aforementioned structures. We found that, in general, for auditory categorical stimuli the learning difficulty ordering of these structures is somewhat different from that of their visual counterparts. However, we also found that this difference may be explained and accurately predicted by a simple encoding mechanism proposed in generalized invariance structure theory (GIST; Vigo, 2013b). We view this result as evidence in support of the proposition that a single basic conceptual system underlies the acquisition of both auditory and visual concepts.
A parallel Helmholtz solver for acoustics and structural acoustics
Authors: Dohrmann Clark R. , Walsh Timothy F.
Published: November 2013

In this talk, we present a parallel Helmholtz solver for the solution of acoustic and structural acoustic problems in the frequency domain. The solver is based on overlapping Schwarz domain decomposition concepts for parallelism, and artificial structural damping is introduced in the preconditioner to deal with resonant or near resonant conditions at the subdomain level. An efficient method to solve problems over a range of frequencies is also described. Numerical examples are presented for acoustic and structural acoustic problems, as well as a study of solver performance for higher order finite element discretizations.
Computational methods for the interior structural acoustics of small spaces
Authors: Grosh Karl , Li Yizeng , Littrell Robert
Published: November 2013

In some biomechanical systems and micro-electro-mechanical systems (MEMS), the interaction of a viscous compressible fluid confined in a space bounded in part by a flexible structure is of central importance. Two specific examples are MEMS microphones (condenser or piezoelectric) and the cochlea. In both the manmade and biological acoustical sensor, the interior space is typically smaller than an acoustic wavelength, and a successful design involves trade-offs between sensitivity, bandwidth, and noise (including thermal, mechanical, electrical, or channel generated noise); the latter two criteria depend critically on the viscous and thermal forces in the system. A direct numeric approach to modeling viscous and thermal effects is often prohibitively expensive, as boundary layers must be resolved in the mesh. In this talk, we will present approximate methods that enable the inclusion of viscothermal effects in a computational framework. In particular, a variational approach amenable to inclusion in a finite element based code will be presented. Results for this method, which retains the accuracy of a Navier-Stokes formulation with the computational cost of a standard scalar acoustic formulation, will be given along with the limitations of the method and a discussion of alternative numerical approaches.
Convolution formulations for non-negative intensity in a plane
Authors: Williams Earl G.
Published: November 2013

New spatial convolution formulas for a variant of the active normal intensity in planar coordinates have been derived that use measured pressure or normal velocity near-field holograms to construct a positive-only (outward) intensity distribution in the plane, quantifying the areas of the vibrating structure that produce radiation to the far-field. This is an extension of the outgoing-only (unipolar) intensity technique recently developed for arbitrary geometries by Steffen Marburg. The method is applied independently to pressure and velocity data measured in a plane close to the surface of a point-driven, unbaffled rectangular plate in the laboratory. It is demonstrated that the sound producing regions of the structure are clearly revealed using the derived formulas and that the spatial resolution is limited to a half-wavelength. A second set of formulas called the hybrid-intensity formulae are also derived which yield a bipolar intensity using a different spatial convolution operator, again using either the measured pressure or velocity. Using the experiment results it is shown that the velocity formula yields the classical active intensity and the pressure formula an interesting hybrid intensity that may be useful for source localization. Computations are fast and carried out in real space without Fourier transforms into wavenumber space. [Work supported by the Office of Naval Research.]
Sound field alteration through cavity shape design using a Wavelet-Galerkin Method
Authors: Zhang Su , Cheng Li
Published: November 2013

The general problem of internal sound field prediction along with the manipulation of the cavity boundary shape to alter the sound pressure distribution is dealt with in this paper. Owing to the compactly supported orthogonal property of the wavelet and its extraordinary fitting capability, Daubechies wavelet scaling function is used as a global basis function to expand the unknown sound pressure under the general Galerkin framework. The proposed formulation is shown to offer high accuracy on the numerical calculation of the sound pressure field with the use of a remarkably small number of messing points. A genetic based shape optimization algorithm is proposed and demonstrated. As an example, an enclosure with an inner rigid acoustic screen is investigated. By optimizing the shape of the screen, the sound pressure level within a chosen area is successfully reduced. Results show the remarkable potentials of the proposed approach as a topology optimal tool for the general inner sound field problems.
A plane wave method for modeling acoustic variables in cavities
Authors: Kamrath Matthew , Koopmann Gary
Published: November 2013

The pressure field within a cavity that contains a homogeneous fluid is modeled in the frequency domain as a superposition of N plane waves with arbitrary orientations and unknown complex amplitudes. Specifying the pressure, the normal velocity, or the specific impedance at N locations produces a system of N linear equations with N unknowns. Then, solving for the complex amplitudes yields an approximation of the pressure and velocity fields inside the cavity. Preliminary comparisons to analytic results are presented.
Influence of cross-sectional discontinuity on the damping characteristics of viscoelastically supported rectangular plates
Authors: Park Jeongwon , Ahn Sangkeun , Yoo Ji Woo , Park Junhong
Published: November 2013

Cross-sectional shape of a structure is one of the important design parameter associated with the vibration responses and resulting sound radiation. In this study, the influence of cross-sectional discontinuity on the vibration characteristics of plate structures was investigated. The variation of cross-sectional geometry in the rectangular plate was modeled as the change of bending stiffness for flexural wave propagation analysis. The complex translational and rotational stiffness at plate edges were used for modeling of the damping at the boundaries. The ratio between the incident and reflected waves from the boundaries was predicted for the flexural waves of different wavelengths to analyze the effect of support stiffness on the vibration damping. Using the wave propagation model, the condition of the viscoelastic boundary properties and the discontinuous flexural stiffness of plate for minimum reflection ratio, i.e., maximum dissipation of the vibration was calculated. Modal damping characteristics of the plate with and without the discontinuity in the cross-section were measured and compared to the predicted reflection ratios. The measured damping ratios on the different boundary conditions showed similar pattern with the predicted vibration energy dissipation at the viscoelastic supports.
A further comparison of fundamental frequency tracking algorithms
Authors: Hu Hongbing , Guzewich Peter , Zahorian Stephen
Published: November 2013

“Yet another Algorithm for Pitch Tracking -YAAPT” was published in a 2008 JASA paper (Zahorian and Hu), with additional experimental results presented at the fall 2012 ASA meeting in Kansas City. The results presented in both the journal paper and at the fall 2012 meeting indicated that YAAPT generally has lower error rates than other widely used pitch trackers (YIN, PRAAT, and RAPT). However, even YAAPT-created pitch tracks had significant “large” errors (pitch doubling and pitch-halving) for both clean and noisy speech. Recently additional post-processing heuristics have been incorporated to reduce the incidence of these type errors—thus reducing the need for hand correcting pitch tracks for situations where extremely accurate tracks are desired. For the case of an all-voiced track, interpolation through unvoiced intervals has been improved. The updated version of YAAPT is presented along with experimental results. The experiments are conducted with multiple databases, including British English, American English, and Mandarin Chinese. For most conditions evaluated, YAAPT gives better performance than the other fundamental frequency trackers.
The effect of non-linear dimension reduction on Gabor filter bank feature space
Authors: Gupta Hitesh A. , Raju Anirudh , Alwan Abeer
Published: November 2013

In this paper, we modify the Gabor feature extraction process, while applying the Gabor filters on the power-normalized spectrum and concatenating with power normalized cepstrum coefficients (PNCC), for noise robust large vocabulary continuous speech recognition. In Chang et al., ICASSP (2013), a similar Gabor filter bank (GBFB) feature set with multi-layer perceptron (MLP) processing (to reduce the feature dimension) has been used with mel frequency cepstrum coefficients showing improvements on Aurora-2 and renoised Wall Street Journal corpora. On a subset of the Aurora-4 database (only male), our method has shown promising results (when using PCA) being 7.9% better than 39-dimensional PNCC features. But, the GBFB features are a rich representation of the speech spectrogram (as an overcomplete basis), and an appropriate dimension reduction/manifold learning technique is the key to generalizing these features for the large vocabulary task. Hence, we propose the use of Laplacian Eigenmaps to obtain a reduced manifold of 13 dimension (from a 564-dimensional GBFB feature set) for the training dataset with a MLP being used to learn the mapping so that the same can be applied to out-of-sample points, i.e., the test dataset. The reduced GBFB features are then concatenated with the 26-dimension PNCC plus acceleration coefficients. This technique should lead to better accuracies as speech lies on a non-linear manifold rather than a linear feature space. [This project was supported in part by DARPA.]
An analysis of firefighter personal safety alarm effectiveness on the fire ground
Authors: Ford Kyle , Habeeb Mudeer , Suits Joelle , Abbasi Mustafa , Wilson Preston S. , Ezekoye Ofodike
Published: November 2013

For firefighters in the line of duty, the last line of defense and chance for rescue oftentimes relies on the effectiveness of their Personal Alert Safety System (PASS) devices. When activated, a PASS device emits an alarm signal to notify others that a firefighter is in distress. However, there have been notable instances where PASS devices have confused rescue personnel or created a more hazardous situation, for instance, when noise interference originating from other objects is involved. This research compiles data from various sources, for example, firefighter near miss reports and National Institute for Occupational Safety and Health (NIOSH) fatality reports, regarding PASS device effectiveness. The research will investigate the causes of confusion and danger as well as take a look at the situations where the device achieved its goal and was able to save a life. The implications of discovering how interfering noises can render PASS devices ineffective could save several lives in the future and ultimately lead to increased firefighter safety.
Simulated acoustical environments for the evaluation of vocal effort
Authors: Whiting Jennifer , Leishman Timothy , Hunter Eric
Published: November 2013

Realistic simulations of acoustical environments allow researchers to quickly manipulate the auditory experiences of human subjects. For studies investigating human speakers’ perceptions of their own voices, a mixed-reality environment is most suitable. In this work, we have developed a system to create low-latency real-time convolutions of speakers’ voices with simulated room impulse responses at their ears. The latter are based in part on measured voice directivity patterns. The simulated rooms included classrooms, lecture halls, and auditoria. They were all simulated for human speakers within an anechoic chamber. We also added realistic noise to the simulations, including chatter and other ambient effects, and measured the subjects’ vocal efforts. The ultimate aim of the simulation and measurement system is to assess teachers’ vocal efforts in classrooms and other settings with easily controlled acoustical conditions. However, the setup may also be easily adapted to other studies for speech or music.
A critical analysis of the “Wind Turbine Health Impact Study: Report of Independent Expert Panel”
Authors: Schomer Paul D. , Pamidighantam Pranav K.
Published: November 2013

The “Wind Turbine Health Impact Study: Report of Independent Expert Panel” study, herein the “Massachusetts study,” says: “The Massachusetts Department of Environmental Protection (MassDEP) in collaboration with the Massachusetts Department of Public Health (MDPH) convened a panel of independent experts to identify any documented or potential health impacts of risks that may be associated with exposure to wind turbines, and, specifically, to facilitate discussion of wind turbines and public health based on scientific findings.” It continues to say: “The scope of the Panel’s effort was focused on health impacts of wind turbines per se.” The Massachusetts study treats health affects broadly in accordance with WHO and includes direct health effects, annoyance, and sleep disruption. In many ways, the Massachusetts study is a critique of the literature relating to wind farm acoustic emissions and health effects. This paper is a critique of the critics. In particular, this critique examines some of the physical acoustic findings and some of the social survey findings. The Massachusetts study employed very strict standards to what they deemed to be quality, acceptable studies, and it is only fair that they be judged by their own criteria. It is the judgment of this reviewer that they failed.
Measuring wind turbine infrasound in the presence of wind
Authors: Carman Richard , Amato Michael
Published: November 2013

A windscreen enables noise measurements to be made as accurately as possible under typical field conditions. Measuring wind turbine noise presents a greater level of difficulty than normal. For there to be wind turbine noise, there needs to be wind for the turbines to operate. Greater wind turbine noise is generally associated with higher wind speeds. Multiple windscreens have been found to significantly reduce artificial wind noise in the range of hearing of 20 to 20 kHz, but cannot reduce the very low frequency pressure fluctuations associated with the movement of air during gusts of wind or in the case of interior measurements fluctuations due to wind pressurizing the building. Wind turbines have been demonstrated by others to produce infrasound in the range of 0.5 to 10 Hz. Measuring infrasound in the presence of local wind is a challenge, since finding a less windy time is not an option. Area-wide measurements of wind turbine noise were conducted at two wind turbine facilities. In analyzing the recorded data, a cross-spectral method was used to reduce the transient effects of local wind in the infrasound range. The technique for doing this is presented and its effect on the data is discussed.
Acoustic interaction as a primary cause of infrasonic spinning mode generation and propagation from wind turbines
Authors: Dooley Kevin A. , Metelka Andy
Published: November 2013

Relatively balanced load and velocity related pressure waves from the rearward facing surface of each rotor blade, are at a frequency of 1 cycle per revolution of the turbine and are phase shifted by 120 degrees from each other. The superposition of these infrasonic waves destructively interfere. This action results in a non-propagating rotor locked mode; however, the shielding (reflecting) effect of the tower as each blade passes, interrupts the balanced destructive interference for a small portion of rotor angle three times per revolution. The momentary un-balance between the destructive interfering waves results in the generation of Tyler-Sofrin spinning mode series, which propagate into the far field. The spinning mode radiation angles, coupled with the low decay rate of infrasound, result in higher far field sound pressure levels than would be predicted for a point source. An analysis approach partially derived from Tyler-Sofrin (1962) is presented. Field microphone data including phase measurements identifying spinning modes are also presented.
Aeroacoustics of volcanic jets: An overview
Authors: Matoza Robin S. , Fee David , Gee Kent L. , Neilsen Tracianne B. , Ogden Darcy E.
Published: November 2013

Explosive volcanic eruptions can inject large volumes of ash into heavily traveled air corridors; they pose a significant societal and economic hazard. They also generate large amplitude atmospheric infrasound waves (~0.01-20 Hz), which can be recorded at thousands of kilometers from the eruption and can provide detailed information on the timing, duration, and relative vigor of the volcanic explosions. In order to provide more detail about the eruption process based on acoustic signals, a quantitative model for the acoustic source process within the volcanic eruption column is needed. Volcanic eruption columns are modeled by a momentum-driven jet flow, transitioning with altitude into a thermally buoyant plume. Infrasound recordings from such activity resemble the large-scale turbulence similarity spectrum, indicating that large-scale volcanic jet flows generate an infrasonic form of jet noise. However, volcanic jet noise deviates from pure-air laboratory jet noise because of complexities such as multiphase flow (especially loading with ash particles); nozzle/crater geometry and roughness; buoyancy effects; and high temperature and density effects. We propose a new framework for understanding acoustic sources at volcanoes based on aeroacoustics research, which is being developed through multi-disciplinary integration of field, numerical, and laboratory studies.
Nonlinear acoustics of combustion instability in solid-propellant rocket motors
Authors: Lee Hunki , Park Taeyoung , Ohm Won-Suk , Lee Dohyung
Published: November 2013

Combustion instability, a large oscillation of pressure in a combustion chamber, is known to be a major source of rocket failure. A common approach to analyzing combustion instability is to regard it as an acoustical phenomenon in an enclosure, driven by the combustion process occurring in a thin region near the grain (solid propellant). Because of the large pressure excursion associated with combustion instability, it exhibits many salient features of nonlinear wave process such as waveform distortion, shock formation, and even chaotic behaviors. In this paper, a comprehensive analytic model for combustion instability of a solid rocket motor is presented. Our focus is on the way in which nonlinearity manifests itself under complex grain geometry, where the acoustic modes can be either harmonically or anharmonically related. Predictions from the model are compared with the static test data for a few representative rockets.
Line source response from geotechnical data
Authors: Glickman Gary
Published: November 2013

Predicting groundborne noise and vibration environmental impacts associated with rail transit projects involves determination of the line source response (LSR) to characterize ground vibration propagation characteristics. The presentation discusses the use of geotechnical data to develop model LSRs. GIS is then used to apply model LSR data on a larger scale and perform a detailed analysis using Federal Transit Administration (FTA) methodology, which can be refined with field testing at a later stage. Conceptual track vibration mitigation measures are discussed for controlling groundborne noise and vibration to nearby receptors.
Monitoring material nonlinearity and attenuation variations in mortar subjected to freezing-thawing cycles
Authors: Eiras Jesus N. , Kundu Tribikram , Popovics John S. , Monzó J. , Borrachero M. V. , Payá J.
Published: November 2013

Standard vibration resonance frequency tests have been widely used for prediction of material modulus of elasticity and for monitoring damage in cement-based materials. More recently, dynamic non-classical nonlinear analyses show promise for damage diagnosis through a variety of test methods that are generally called nonlinear elastic wave spectroscopy (NEWS) techniques. In this study, we monitor the nonlinear dynamic behavior and mechanical wave attenuation of mortar subjected to varying numbers of freezing-thawing cycles. The nonlinear analysis is deployed using a new signal processing technique applied to standard resonance frequency test generated data. The proposed technique is demonstrated on damaged and un-damaged mortar bar samples.
Noncontact fatigue crack detection using nonlinear wave modulation spectroscopy
Authors: Liu Peipei , Sohn Hoon , Kundu Tribikram
Published: November 2013

Nonlinear wave modulation spectroscopy (NWMS) has been used to evaluate nonlinear acoustic signature of fatigue cracks in materials and thus to get an idea about the degree of material nonlinearity. It is done by generating ultrasonic waves at two different frequencies and measuring their modulation. The choice of two distinct frequencies plays a significant role in NWMS for different structures. In this paper, instead of using signals at two distinct frequencies, only one broadband pulse signal is used as the driving signal, which can be generated by a laser beam. This driving signal generates multi-frequency responses as different resonance frequency modes and/or Lamb wave modes, generated in a plate-like structure. Nonlinear wave modulation occurs among these frequencies when material nonlinearity exists. It increases the sideband energy and the number of peaks in the spectral plots. These two features, namely sideband energy ratio (SER) and sideband peak number (SPN), are extracted from the spectral plots to measure the material nonlinearity caused by fatigue cracks. The noncontact laser system has been built for NWMS measurement by integrating and synchronizing a Q-switched Nd:YAG laser for ultrasonic wave generation and a laser Doppler vibrometer for ultrasonic wave detection. The proposed modified NWMS technique with the noncontact laser system has been successfully used for the identification of metallic plates with fatigue cracks.
Adaptive orthogonal frequency division multiplexing underwater acoustic communications with limited feedback
Authors: Huang Xiaopeng , Song Aijun , Ahmed Walid , Badiey Moshen , Lawrence Victor
Published: November 2013

In orthogonal frequency division multiplexing (OFDM) underwater acoustic (UWA) communications, some subcarriers may be subject to deep fading. If the channel state information (CSI) is available at the transmitter side, adaptive transmission techniques (e.g., power allocation) can be applied to mitigate the selective fading effect and increase the overall performance. Therefore, it is more valuable to analyze the UWA channel with limited CSI feedback. In this paper, we adopt two time-varying shallow water acoustic channels (slow-varying environment and fast-varying environment) as examples. Lloyd algorithm is employed to quantize the CSI at the receiver and construct the codebook, which is also known to the transmitter. Simulation results compare the performance between two different channels, and the performance between a few bits of feedback, perfect feedback, and non-feedback, respectively.
Application of information-theoretic performance measures to optimization of array spatial configurations for underwater acoustic source localization
Authors: Hayward Thomas J.
Published: November 2013

Information-theoretic measures of acoustic source localization performance provide for performance comparisons that are valid across classes of signal processing algorithms and can be used as performance criteria for the optimization of receiver-array spatial configurations for source localization. This work investigates the use of fundamental information-theoretic quantities, including mutual information of source location and processor output and conditional entropy of source location given processor output, as performance criteria for the optimization of array configurations. Applications of these criteria to the optimization of horizontal and vertical arrays are illustrated in examples of Bayesian localization, conventional beamforming, and matched-field processing of the acoustic field of a time-harmonic source in a range-independent shallow-water waveguide. The optimized array spatial configurations are compared with results obtained using traditional (energy-based) performance measures. [Work supported by ONR.]
Test of a towed line array suitable for geoacoustic inversion
Authors: Abdullah Joel , Woodson Neil , Sagers Jason D. , Knobles David P. , Stotts Steven A. , Muir Thomas
Published: November 2013

Small line arrays towed by ships may give a unique, cost effective approach for acoustic reconnaissance of seabed characteristics in littoral seas. A 16 element, 1 m spaced, towed line array was designed and developed at ARL:UT for the purpose of ship-towed statistical inference of the seabed. The towed array was tested at the ARL:UT Lake Travis Test Station under a variety of conditions to study array performance. Additional non-acoustic sensors provided information about array shape, stability, and drag as a function of speed, depth, and tail termination. Acoustic data were collected during the test and processed with an adaptive beamformer yielding high SNR, well-localized signals from a fixed 500 Hz source as well as the received signals from small boats of opportunity. The acoustic data are analyzed with a statistical inference approach to estimate the geoacoustic properties of the lake bottom. [Work supported by the ARL:UT internal research and development program.]