bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporary threshold shifts in the bottlenose dolphin (Tursiops truncatus), varying noise duration and intensity
Authors: Mooney T. Aran , Nachtigall Paul E. , Au Whitlow W. L. , Breese Marlee , Vlachos Stephanie
Published: October 2013

There is much concern regarding increasing noise levels in the ocean and how it may affect marine mammals. However, there is a little information regarding how sound affects marine mammals and no published data examining the relationship between broadband noise intensity and exposure duration. This study explored the effects of octave-band noise on the hearing of a bottlenose dolphin by inducing temporary hearing threshold shifts (TTS). Sound pressure level (SPL) and exposure duration were varied to measure the effects of noise duration and intensity. Hearing thresholds were measured using auditory evoked potentials before and after sound exposure to track and map TTS and recovery. Shifts were frequency dependent and recovery time depended on shift and frequency, but full recovery was relatively rapid, usually within 20 min and always within 40 min. As exposure time was halved, TTS generally occurred with an increase in noise SPL. However, with shorter, louder noise, threshold shifts were not linear but rather shorter sounds required greater sound exposure levels to induce TTS, a contrast to some published literature. From the data a novel algorithm was written that predicts the physiological effects of anthropogenic noise if the intensity and duration of exposure are known.
Representations involved in short-term versus long-term word learning by preschool children with and without phonological disorders
Authors: Storkel Holly , Hoover Jill , Maekawa Junko
Published: October 2013

This study explores whether sublexical (i.e., individual sound) and/or lexical (i.e., whole-word) representations contribute to word learning and whether these contributions change across short-term versus long-term learning. Sublexical representations were indexed by phonotactic probability, the likelihood of occurrence of a sound sequence, whereas lexical representations were indexed by neighborhood density, the number of similar sounding words. Thirty-four preschool children participated in a short-term word learning task that exposed them to nonwords varying in phonotactic probability and neighborhood density and tested learning of these nonwords. Long-term learning was assessed through comprehension and production of real words varying in phonotactic probability and neighborhood density. Results showed that phonotactic probability and neighborhood density equally influenced short-term word learning. In contrast, long-term word learning was affected primarily by neighborhood density. Thus, both sublexical and lexical representations appeared to play a role in short-term learning, but only lexical representations played a primary role in long-term retention. This pattern held for both children with normal phonological development and children with phonological delays. However, the direction of the effect of neighborhood density for short-term word learning varied by group status, suggesting differences in the use of lexical representations during short-term learning. [Work supported by NIH.]
An extended lumped-element model and parameter estimation technique to predict loudspeaker responses with possible surround-dip effects
Authors: Sagers Jason D. , Leishman Timothy W. , Blotter Jonathan D.
Published: November 2013

Lumped-element models have long been used to estimate the basic vibration and radiation characteristics of moving-coil loudspeakers. The classical low-frequency model combines and simplifies several important driver elements, predicting only a single mechanical resonance wherein the diaphragm (e.g., cone and dust cap) and the inner portion of the surround move together as an effective piston. Even if the diaphragm maintains piston-like motion with increasing frequency, the flexible surround eventually vibrates out of phase, producing another resonance whereby a noticeable “surround dip” may occur in the radiated pressure spectrum. The classical model is unable to predict this behavior. This paper explores an extended lumped-element model that better characterizes the distinct diaphragm, surround, spider, and other properties of a loudspeaker in a plane rigid baffle. It extends effective modeling to mid frequencies and readily predicts a surround dip in the radiated response. The paper also introduces a method to estimate model parameters using a scanning laser Doppler vibrometer, a surround resonance indicator function, and a constrained optimization routine. The approach is validated by its ability to better predict on-axis pressure responses of several baffled loudspeakers in an anechoic environment.
Simulation of nonlinear Westervelt equation for the investigation of acoustic streaming and nonlinear propagation effects
Authors: Solovchuk Maxim , Sheu Tony W. H. , Thiriet Marc
Published: November 2013

This study investigates the influence of blood flow on temperature distribution during high-intensity focused ultrasound (HIFU) ablation of liver tumors. A three-dimensional acoustic-thermal-hydrodynamic coupling model is developed to compute the temperature field in the hepatic cancerous region. The model is based on the nonlinear Westervelt equation, bioheat equations for the perfused tissue and blood flow domains. The nonlinear Navier-Stokes equations are employed to describe the flow in large blood vessels. The effect of acoustic streaming is also taken into account in the present HIFU simulation study. A simulation of the Westervelt equation requires a prohibitively large amount of computer resources. Therefore a sixth-order accurate acoustic scheme in three-point stencil was developed for effectively solving the nonlinear wave equation. Results show that focused ultrasound beam with the peak intensity 2470 W/cm2 can induce acoustic streaming velocities up to 75 cm/s in the vessel with a diameter of 3 mm. The predicted temperature difference for the cases considered with and without acoustic streaming effect is 13.5 °C or 81% on the blood vessel wall for the vein. Tumor necrosis was studied in a region close to major vessels. The theoretical feasibility to safely necrotize the tumors close to major hepatic arteries and veins was shown.
Enhancing sound absorption and transmission through flexible multi-layer micro-perforated structures
Authors: Bravo Teresa , Maury Cédric , Pinhède Cédric
Published: November 2013

Theoretical and experimental results are presented into the sound absorption and transmission properties of multi-layer structures made up of thin micro-perforated panels (ML-MPPs). The objective is to improve both the absorption and insulation performances of ML-MPPs through impedance boundary optimization. A fully coupled modal formulation is introduced that predicts the effect of the structural resonances onto the normal incidence absorption coefficient and transmission loss of ML-MPPs. This model is assessed against standing wave tube measurements and simulations based on impedance translation method for two double-layer MPP configurations of relevance in building acoustics and aeronautics. Optimal impedance relationships are proposed that ensure simultaneous maximization of both the absorption and the transmission loss under normal incidence. Exhaustive optimization of the double-layer MPPs is performed to assess the absorption and/or transmission performances with respect to the impedance criterion. It is investigated how the panel volumetric resonances modify the excess dissipation that can be achieved from non-modal optimization of ML-MPPs.
Comparison of a short-time speech-based intelligibility metric to the speech transmission index and intelligibility data
Authors: Payton Karen L. , Shrestha Mona
Published: November 2013

Several algorithms have been shown to generate a metric corresponding to the Speech Transmission Index (STI) using speech as a probe stimulus [e.g., Goldsworthy and Greenberg, J. Acoust. Soc. Am. 116, 3679–3689 (2004)]. The time-domain approaches work well on long speech segments and have the added potential to be used for short-time analysis. This study investigates the performance of the Envelope Regression (ER) time-domain STI method as a function of window length, in acoustically degraded environments with multiple talkers and speaking styles. The ER method is compared with a short-time Theoretical STI, derived from octave-band signal-to-noise ratios and reverberation times. For windows as short as 0.3 s, the ER method tracks short-time Theoretical STI changes in stationary speech-shaped noise, fluctuating restaurant babble and stationary noise plus reverberation. The metric is also compared to intelligibility scores on conversational speech and speech articulated clearly but at normal speaking rates (Clear/Norm) in stationary noise. Correlation between the metric and intelligibility scores is high and, consistent with the subject scores, the metrics are higher for Clear/Norm speech than for conversational speech and higher for the first word in a sentence than for the last word.
Beamforming of sound from two-dimensional arrays using spatial matched filters
Authors: Yen Jesse T.
Published: November 2013

Fully-sampled two-dimensional (2D) arrays can have two-way focusing of the ultrasound beam in both lateral directions leading to high quality, real-time three-dimensional (3D) imaging. However, fully-sampled 2D arrays with very large element counts (>16 000) are difficult to manufacture due to interconnect density and large element electrical impedance. As an alternative, row-column or crossed electrode arrays have been proposed to simplify transducer fabrication and system integration. These types of arrays consist of two one-dimensional arrays oriented perpendicular to each other. Using conventional delay-and-sum beamforming, each array performs one-way focusing in perpendicular lateral directions which yield higher sidelobe and acoustic clutter levels compared to fully-sampled 2D arrays with two-way focusing. In this paper, the use of spatial matched filters to improve focusing of row-column arrays is investigated. On receive, data from each element are first spatial match filtered in the elevation direction. After summation, the data are filtered again in the azimuth direction. Beam widths comparable to one-way focusing are seen in azimuth and beam widths comparable to two-way focusing are achieved in elevation. 3D beam patterns from computer simulation results using a 7.5 MHz 128 × 128 row-column array are shown with comparison to a fully sampled 2D array.
Experimental verification of enhanced sound transmission from water to air at low frequencies
Authors: Calvo David C. , Nicholas Michael , Orris Gregory J.
Published: November 2013

Laboratory measurements of enhanced sound transmission from water to air at low frequencies are presented. The pressure at a monitoring hydrophone is found to decrease for shallow source depths in agreement with the classical theory of a monopole source in proximity to a pressure release interface. On the other hand, for source depths below 1/10 of an acoustic wavelength in water, the radiation pattern in the air measured by two microphones becomes progressively omnidirectional in contrast to the classical geometrical acoustics picture in which sound is contained within a cone of 13.4° half angle. The measured directivities agree with wavenumber integration results for a point source over a range of frequencies and source depths. The wider radiation pattern owes itself to the conversion of evanescent waves in the water into propagating waves in the air that fill the angular space outside the cone. A ratio of pressure measurements made using an on-axis microphone and a near-axis hydrophone are also reported and compared with theory. Collectively, these pressure measurements are consistent with the theory of anomalous transparency of the water-air interface in which a large fraction of acoustic power emitted by a shallow source is radiated into the air.
Aircraft noise-induced awakenings are more reasonably predicted from relative than from absolute sound exposure levels
Authors: Fidell Sanford , Tabachnick Barbara , Mestre Vincent , Fidell Linda
Published: November 2013

Assessment of aircraft noise-induced sleep disturbance is problematic for several reasons. Current assessment methods are based on sparse evidence and limited understandings; predictions of awakening prevalence rates based on indoor absolute sound exposure levels (SELs) fail to account for appreciable amounts of variance in dosage-response relationships and are not freely generalizable from airport to airport; and predicted awakening rates do not differ significantly from zero over a wide range of SELs. Even in conjunction with additional predictors, such as time of night and assumed individual differences in “sensitivity to awakening,” nominally SEL-based predictions of awakening rates remain of limited utility and are easily misapplied and misinterpreted. Probabilities of awakening are more closely related to SELs scaled in units of standard deviates of local distributions of aircraft SELs, than to absolute sound levels. Self-selection of residential populations for tolerance of nighttime noise and habituation to airport noise environments offer more parsimonious and useful explanations for differences in awakening rates at disparate airports than assumed individual differences in sensitivity to awakening.
Using the auditory steady-state response to assess temporal dynamics of hearing sensitivity during bottlenose dolphin echolocation
Authors: Finneran James J. , Mulsow Jason , Houser Dorian S.
Published: November 2013

The auditory steady-state response (ASSR) to an external tone was measured in an echolocating dolphin to determine if hearing sensitivity changes could be tracked over time scales corresponding to single click-echo pairs. Individual epochs containing click-echo pairs were first extracted from the instantaneous electroencephalogram. Epochs were coherently averaged using the external tone modulation rate as a timing reference, then Fourier transformed using a sliding, 10-ms temporal window to obtain the ASSR amplitude as a function of time. The results revealed a decrease in the ASSR amplitude at the time of click emission, followed by a 25–70 ms recovery.
Discrimination of virtual auditory distance using level and direct-to-reverberant ratio cues
Authors: Kolarik Andrew , Cirstea Silvia , Pardhan Shahina
Published: November 2013

The study investigated how listeners used level and direct-to-reverberant ratio (D/R) cues to discriminate distances to virtual sound sources. Sentence pairs were presented at virtual distances in simulated rooms that were either reverberant or anechoic. Performance on the basis of level was generally better than performance based on D/R. Increasing room reverberation time improved performance based on the D/R cue such that the two cues provided equally effective information at further virtual source distances in highly reverberant environments. Orientation of the listener within the virtual room did not affect performance.
Absolute pitch among students at the Shanghai Conservatory of Music: A large-scale direct-test study
Authors: Deutsch Diana , Li Xiaonuo , Shen Jing
Published: November 2013

This paper reports a large-scale direct-test study of absolute pitch (AP) in students at the Shanghai Conservatory of Music. Overall note-naming scores were very high, with high scores correlating positively with early onset of musical training. Students who had begun training at age ≤5 yr scored 83% correct not allowing for semitone errors and 90% correct allowing for semitone errors. Performance levels were higher for white key pitches than for black key pitches. This effect was greater for orchestral performers than for pianists, indicating that it cannot be attributed to early training on the piano. Rather, accuracy in identifying notes of different names (C, C#, D, etc.) correlated with their frequency of occurrence in a large sample of music taken from the Western tonal repertoire. There was also an effect of pitch range, so that performance on tones in the two-octave range beginning on Middle C was higher than on tones in the octave below Middle C. In addition, semitone errors tended to be on the sharp side. The evidence also ran counter to the hypothesis, previously advanced by others, that the note A plays a special role in pitch identification judgments.
Researches and applications of the ultrasonic emulsifications and dispersions
Authors: Quanlu Li , Yinhong Zhang , Jing Wu
Published: November 2013

This paper defines power ultrasonics and their two important directions: Ultrasonic emulsification and dispersion from a practical point of view, brief reports on recent research results are ultrasonic emulsification to be used for the preparation of composite electrorheological fluid, and ultrasonic dispersion to be used dispersion as a new type cold cloud catalytic agent metaldehyde [CH3CH]4-6 (this is used for artificial rain), etc., and produce good results or gain progress. Then, the principle and applications of power ultrasonics (including magnetostriction type ultrasonic transducer and piezoelectric type ultrasonic transducer) in the emulsification or dispersion, are pointed out. Also, ultrasonic extensive applications in chemistry, materials, and life sciences are briefly introduced.
Attack transients in free reed instruments
Authors: Biernat Jennifer , Cottingham James P.
Published: November 2013

Attack transients of harmonium-type reeds from American reed organs have been studied in a laboratory setting with the reeds mounted on a wind chamber. Several methods were used to initiate the attack transients of the reeds, and the resulting displacement and velocity waveforms were recorded using a laser vibrometer system and electronic proximity sensors. The most realistic procedure had a pallet valve mechanism simulating the initiation of an attack transient that depressing an organ key would provide. Growth rates in vibrational amplitude were then measured over a range of blowing pressures. Although the fundamental transverse mode is dominant in free reed oscillation, the possibility of higher transverse modes and torsional modes being present in transient oscillation was also explored. The reeds studied are designed with a spoon-shaped curvature and a slight twist at the free end of the reed tongue, intended to provide a more prompt response, especially for larger, lower-pitched reeds for which a slow attack can be a problem. The effectiveness of this design has been explored by comparing these reeds with equivalent reeds without this feature. [Work supported by National Science Foundation REU Grant PHY-1004860.]
Marching band hearing responses: Indoor rehearsal vs outdoor performance configurations
Authors: Sweitzer Glenn E.
Published: November 2013

Marching band performer responses are gathered to compare how well each performer hears: (1) oneself playing; (2) others playing the same part and instrument; and (3) others playing different parts, by instrument. The measurement protocol is repeated in an indoor purpose-built band rehearsal venue with adjustable sound diffusive vs absorptive wall treatments and, at an open-air outdoor performance venue (grass playing field). All scaled responses are gathered using a personal response system, providing immediate, simultaneous, and anonymous responses that can be compared online. Prior to each set of responses, all performers play together a well-rehearsed score. Responses vary indoors by absorptive treatment and band configuration and, outdoors, by band configuration. Discussion will focus on how marching bands, indoors or outdoors, might be reconfigured to improve hearing for performers, directors, and audiences.
Reconstruction of arbitrary sound fields with a rigid-sphere microphone array
Authors: Fernandez-Grande Efren
Published: November 2013

Over the last few years, several studies have examined the potential of using rigid-sphere microphone arrays for reconstructing sound fields with near-field acoustic holography (NAH). The existing methods provide a reconstruction of the sound field based on a spherical harmonic expansion. However, because of the basis functions used, the reconstruction can only be performed in spherical surfaces concentric to the array and inside the source-free region, which imposes a severe limitation on the applicability of the technique due to geometrical constrains. In this paper, a method based on an equivalent source model is proposed, where a combination of point sources is used to describe the incident sound field on the array. This method makes it possible to reconstruct the entire sound field at any point of the source-free domain without being restricted to a spherical surface. Additionally, this approach adds versatility (the reconstruction can be based on the microphones that are closer to the source, for a better conditioning of the problem, or also use non-uniform sampling). The method is presented, examined numerically and experimentally, and compared to the existing methods based on a spherical harmonic expansion.
Artificial reverberation using multi-portacoustic elements
Authors: Koontz Warren L.
Published: November 2013

Multi-port acoustic elements, including simple two-port elements, can be used both to model acoustic systems and to create acoustic signal processing structures. This paper focuses on the latter, specifically on networks of multi-port acoustic elements that create an artificial reverberation effect. We will introduce some basic two-port and multi-port building blocks, each characterized by a scattering matrix and demonstrate frequency domain and time domain analyses of networks of these elements. We will then propose and investigate networks that create artificial reverberation. We will implement these structures using MATLAB and evaluate and compare them with some existing approaches including the Schroeder reverberator and feedback delay networks. Comparisons will be based on the computed impulse response as well as sound files.
Online sound restoration system for digital library applications
Authors: Czyzewski Andrzej , Cichowski Janusz , Kupryjanow Adam , Kostek Bozena
Published: November 2013

Audio signal processing algorithms were introduced to the new online non-commercial service for audio restoration intended to enhance the content of digitized audio repositories. Missing or distorted audio samples are predicted using neural networks and a specific implementation of the Jannsen interpolation method based on the autoregressive model (AR) combined with the iterative restoring of missing signal samples. Since the distortion prediction and compensations algorithms are computationally complex, an implementation which uses parallel computing has been proposed. Many archival recordings are at the same time clipped and affected by wideband noise. To restore those recordings, the algorithm based on the concatenation of signal clipping reduction and spectral expansion was proposed. The clipping reduction algorithm uses an intelligent interpolation to replace distorted samples with the predicted ones based on learning algorithms. Next, spectral expansion is performed in order to reduce the overall level of noise. The online service has been extended with some copyright protection mechanisms. Immunity of watermarks to the sound restoration is discussed with regards to low-level music feature vectors embedded as watermarks. Then, algorithmic issues pertaining watermarking techniques are briefly recalled. The architecture of the designed system together with the employed workflow for embedding and extracting the watermark are described. The implementation phase is presented and the experimental results are reported.
Observation and modeling of three-dimensional basin scale acoustics
Authors: Heaney Kevin D. , Campbell Richard L. , Prior Mark , Zampolli Mario
Published: November 2013

In this paper, an overview of some of the basin-scale recordings of the International Monitoring System of the Comprehensive Test Ban Treaty will be presenting, including observations of distant earthquakes, under-sea volcanoes and cracking ice-sheets. Long range experiments were conducted in 1960 when nearly antipodal receptions were made at Bermuda from SuS charges deployed off the coast of Australia. Three-dimensional propagation effects was an important part of the propagation. For propagation ranges of thousands of kilometers, interaction with islands, ridges and seamounts is expected to influence propagation. Previous modeling approaches have been either a fully 3D ray approach, a hybrid adiabatic mode-ray approach and a hybrid adiabatic mode—PE approach. In this paper, we present the a global scale three-dimensional split-step Pade Parabolic Equation. Model results are compared with several direct observations of arrivals that are clearly in the 2D propagation shadow. The impact of 3D propagation on the coverage maps of the CTBTO are significant, relative to current 2D predictions.
The mode view of long-range propagation through oceanic internal waves
Authors: Henyey Frank S.
Published: November 2013

For long-range acoustic propagation in the ocean, calculation of internal wave effects by ray tracing is far from accurate. Full wave methods must be used. An unperturbed normal mode simulation has been developed for this case. Simulations have been carried out with a single-mode starting field, with a sound speed profile measured in the 2010 Philippine Sea experiment, and internal waves consistent with measurements at the same region and same time. Modes were chosen that turn around half way between the sound axis and the surface. The frequency is 100 Hz, appropriate for long-range propagation experiments. Ensemble averaged mode intensities are consistent with transport theory results, but the individual mode intensities as a function of range are very inconsistent with a random walk ("diffusion") in mode number space.
Ultrasound bladder vibrometry for evaluation of bladder compliance: Preliminary in vivo results
Authors: Mehrmohammadi Mohammad , Nenadic Ivan Z. , Urban Matthew W. , Greenleaf James F. , Alizad Azra , Husmann Douglas A. , Mynderse Lance A. , Fatemi Mostafa
Published: November 2013

Bladder compliance is defined as bladder’s ability to expand in volume without a significant change in pressure. The bladder wall is a multi-layered structure including a muscular layer and fibrous connective tissue. As the percent of connective tissue in the bladder interstitium increases compared to smooth muscle, the bladder becomes more rigid and less capable of expanding during filling. Currently, urodynamic studies (UDS) are considered as the clinical gold standard for bladder compliance assessment. This procedure is invasive and is associated with patient discomfort and is expensive. Ultrasound bladder vibrometry (UBV) is a novel acoustic-radiation-forced-based method for noninvasive assessment of bladder compliance. In UBV, an impulsive acoustic radiation force is focused on the bladder wall (under B-mode ultrasound image guidance) to induce vibrations which may be modeled by as a Lamb wave. High frame rate ultrasound is then utilized to detect the induced waves. This wave motion is then used to estimate the viscoelastic properties and the compliance of the bladder wall. Our results reveal a remarkable agreement between UBV and UDS cystometry measures, suggesting the potential of UBV as a viable clinical tool for the assessment of bladder compliance.
Establishing the admissible waves and the steady state response of a rib-stiffened, layered plate structure subjected to high frequency acoustic loading
Authors: Teferra Kirubel , Cipolla Jeffrey
Published: November 2013

An existing pseudo-analytical, frequency domain solution for wave propagation in coated, ribbed, three-dimensional elastic layered plates excited by acoustic plane waves provides fast solutions for high frequency excitations. The solution methodology, which is found to be numerically unstable under certain conditions, contains a fundamental ansatz regarding the set of excited wave forms expressed through a particular wave number expansion in the direction of periodicity. We propose to identify the set of admissible propagating (and attenuating) waves via an eigenvalue analysis as a preprocessing step when executing the pseudo-analytical solution. A significant challenge lies in determining the admissible waves of structures with periodicity in two-dimensions. The Wave Guide Finite Element (WFE) method leads to a two parameter, nonlinear eigenvalue problem, which is extremely difficult to solve. By formulating the problem with the Scale Independent Element (SIE) formulation, the admissible waves can be expressed through a two-parameter quadratic eigenvalue problem. This formulation overcomes the numerical conditioning issues associated with WFE method. This study compares the aforementioned ansatz with that computed by the SIE formulation as well as the improvements in the numerical stability associated with this additional step. The forced response results are compared to a finite element analysis.
Ultrasonic phased array techniques for composite material evaluation
Authors: Taheri Hossein , Delfanian Fereidoon , Du Jikai
Published: November 2013

The increasing rate of composite materials usage in the industries and researches implies finding the suitable method for testing and evaluation of composite materials. The composites are susceptible to flaws during production and the inspection costs suggest the use of NDT methods. Non-destructive testing is an appropriate method to detect the flaws and anomalies in the materials, however, due to an-isotropic structure of the composite materials, it is required to modify the techniques to find the most appropriate and accurate process for detecting flaws and anomalies in composite materials. The objective of this paper is to evaluate the feasibility and accuracy of nondestructive testing methods with emphasis on ultrasonic phased array technique for the integrity and structural evaluation of composite materials. In this approach three different composite samples were used for testing including one carbon fiber and two glass fiber samples. ultrasound phased array technique evaluated to perform the testing on the composite materials to find the appropriate method and procedure to apply ultrasound phased array techniques on composite materials.
Elastic response of an orthogonally reinforced plate
Authors: Hull Andrew J. , Maguire Jason M.
Published: November 2013

This paper develops a three-dimensional fully elastic analytical model of a solid plate that has two sets of embedded, equally spaced stiffeners that are orthogonal to each other. The dynamics of the solid plate are based on the Navier-Cauchy equations of motion of an elastic body. This equation is solved with unknown wave propagation coefficients at two locations, one solution for the volume above the stiffeners and the second solution for the volume below the stiffeners. The forces that the stiffeners exert on the solid body are derived using beam and bar equations of motion. Stress and continuity equations are then written at the boundaries, and these include the stiffener forces acting on the solid. A two-dimensional orthogonalization procedure is developed, and this produces an infinite number of double indexed algebraic equations. These are all written together as a global system matrix. This matrix can be truncated and solved resulting in a solution to the wave propagation coefficients, which allows the systems displacements to be determined. The model is verified by comparison to thin plate theory and finite element analysis. An example problem is formulated. Convergence of the series solution is discussed.
On fluid-structure interactions of a cloaked submerged spherical shell
Authors: Scandrett Clyde , Vieira Ana M.
Published: November 2013

Backscattering from a cloaked submerged spherical shell is analyzed in the low, mid, and high frequency regimes. Complex poles of the scattered pressure amplitudes using Cauchy residue theory are evaluated in an effort to explain dominant features of the scattered pressure and how they are affected by the introduction of a cloak. The methodology used is similar to that performed by Sammelmann and Hackman in a series of papers written on scattering from an uncloaked spherical shell in the early 1990s. In general, it is found that cloaking has the effect of diminishing the amplitude and shifting tonal backscatter responses. Extreme changes of normal and tangential fluid phase velocities at the fluid-solid interface when cloaking is employed leads to elimination of the “mid-frequency enhancement” near the coincidence frequency for even modestly effective cloaks, while reduction of the “high-frequency enhancement” resulting from the “thickness quasi-resonance” near the cutoff frequency of the symmetric (SB 2) mode require more effective cloaking, but can be practically eliminated by employing a cloak that creates tangential acoustic velocities in excess of the SB 2 mode phase speed near cutoff.
The Ear Club: Ervin R. Hafter’s academic family
Authors: Gallun Frederick J. , Stecker G. Christopher , Loui Psyche , Sarampalis Anastasios
Published: November 2013

Ervin R. Hafter is a direct academic descendent of Wilhelm Wundt, William James, James Cattell, Robert Woodworth, and Warner Brown. Erv’s Ph.D. advisor, Lloyd Jeffress, is one of the most renowned names in binaural hearing theory. For more than 40 years, auditory scientists from around the globe have been traveling to Berkeley, where Erv has been teaching and researching at the University of California, Berkeley, mentoring undergraduate students and Ph.D. students and supervising postdocs. Many of those who worked in Erv's lab have gone on to run labs of their own and have graduated and supervised many of their own students and postdocs, who in turn now run their own labs. This presentation will document the extensive web of connections that all started with the Hafter Lab and the weekly seminar series, the Ear Club, where for decades auditory scientists of all ranges of background and experience have been coming together to talk, listen, and make friends for a lifetime.
Acoustic normal mode fluctuations due to internal waves in the Shallow Water 2006 experiment
Authors: Wan Lin , Badiey Mohsen , Lynch James F.
Published: November 2013

The Shallow Water 2006 (SW06) experiment was a large-scale acoustic experiment conducted on the New Jersey continental shelf in the summer of 2006 with substantial investment from the Office of Naval Research. The main goal of this experiment was to find a detailed understanding of the waveguide during the propagation of broadband acoustic signals in the presence of internal waves (IW). One month of IW events recorded during this experiment has been reconstructed with the aids of densely deployed thermistor strings and ship-borne X-Band radars. The comprehensive IW measurements enabled the study of the correlation between the IW-induced time-varying environment and the acoustic normal mode fluctuations. During this experiment, an L-shaped hydrophone array was moored inside the area with IW measurements. Acoustic sources transmitting for 7.5 min every 30 min starting on the hour were deployed at the shallow end of the across-shelf path and the outer end of the along-shelf path respectively. The acoustic modal fluctuations in modal arrival time, intensity, temporal coherence, and spatial coherence during the aforementioned IW events are analyzed. The relationship between the modal behavior and IW parameters is investigated and possible IW inversion schemes using acoustic measurements are discussed. [Work supported by ONR322OA.]
Detecting voice disguise from speech variability: Analysis of three glottal and vocal tract measures
Authors: Amin Talal B. , German James S. , Marziliano Pina
Published: November 2013

The deliberate attempt by speakers to conceal their identity (voice disguise) presents a challenge for forensics and for automated speaker identification systems. Using a database of natural and disguised voices of three professional voice impersonators, we build on earlier findings (Amin et al., 2012) by exploring how certain glottal and vocal tract measures, including fundamental frequency (f0), glottal timing (Open Quotient), and vowel formants, are exploited to create novel voice identities. Specifically, we explored whether the amount and type of variation exhibited by impersonators can be used to develop a metric for distinguishing natural from disguised voices. As expected, variation in f0 and Open Quotient was speaker-dependent, and corresponded closely to social attributes (i.e., gender/age) of the voice identities involved. In a novel finding, the effects of voice identity on vowel formants were highly dependent on vowel category, and could not be readily characterized as global modifications to the vowel space (Bradlow et al.,1996). We therefore developed a no-reference objective metric for voice disguise that treats formant variability on a vowel-by-vowel basis. This metric consistently assigned high rankings to natural voices (3.3/27 on average). This correlated closely with the subjective disguisedness ratings of 18 naïve listeners, even outperforming them slightly.
Automated acoustic detection and classification of small aircraft
Authors: Sinelnikov Yegor , Sutin Alexander , Sedunov Alexander , Salloum Hady
Published: November 2013

Automated acoustic detection and classification of low flying aircraft can be used for the prevention of illicit operations. In this presentation, we review past techniques and a new acoustic classification and detection technique. The sound detection algorithm is based on locking in narrow frequency components in the spectra of the recorded aircraft sound. The classification algorithm uses tonal components in the spectral and cepstral domains using discrete time window peak picking. A set of chosen classifiers include: fundamental (pitch) frequency extracted by the cepstral analysis, frequency of tonal components with the maximal amplitude, power spectral estimate in various frequency bands, and number of peaks in predefined frequency and frequency windows. Various small single engine aircraft, ultralights, and helicopters are acoustically detected and classified as they approach the sensor. The algorithm enables simultaneous target detection, reduces noise sensitivity, and minimizes classifier feature space, while maintaining good classification separation. The acoustic classification algorithm was incorporated into the Acoustic Aircraft Detection system developed by Stevens. This combination allowed automated Doppler correction of the harmonic lines, the optimal part of the aircraft signal selection, and establishing classification merits based on aircraft track. [This work was funded by DHS S&T.]
Ten years of seismic oceanography: Accomplishments and challenges
Authors: Holbrook W. Steven
Published: November 2013

“Seismic oceanography” (SO)—the use of low-frequency marine seismic reflection data to image thermohaline fine-structure in the water column—began in 2003, with the publication of a paper in Science. Over the past ten years, the nascent SO community has demonstrated that reflection seismology can image thermohaline fine structure, over large areas, from temperature contrasts in the ocean of only a few hundredths of a ̊C. The resulting images illuminate many diverse oceanic phenomena, including fronts, water mass boundaries, internal wave displacements, internal tide beams, eddies, turbulence, and lee waves. Beyond merely producing spectacular images of ocean structure, low-frequency reflections can be processed to produce quantitative estimates of sound speed (and thus ocean temperature), turbulence dissipation, and vertical mode structure over full ocean depths, as long as fine-structure reflections are present. Yet SO has failed to become a standard tool for physical oceanographers, partly due to disciplinary boundaries, and partly due to the perceived high expense of seismic data acquisition. I will present examples of the successes of SO and discuss approaches to meet the challenges to the adoption of SO as a commonly used technique to study physical oceanographic processes.
Multi-degree-of-freedom model of 32(1)-mode cylindrical transducer with inactive elements
Authors: Joseph Nicholas , Haberman Michael R.
Published: November 2013

Piezoelectric transducers with cylindrical geometry are often designed to operate in a radial “breathing” mode. In order to tune their performance in a cost effective way, cylinders can be constructed of alternating active (piezoelectric) and inactive (non-piezoelectric) staves. Existing lumped parameter models for such a ring are based on effective piezoelectric properties of the composite ring which reduce the system to a single degree of freedom corresponding to the breathing motion [Butler, J. Acoust. Soc. Am., 59(2), 480-482, (1976)]. Unfortunately, if the length of the staves is a sufficiently large percentage of the circumference, the transducer may demonstrate a detrimental higher frequency resonance within the desired bandwidth of operation. This parasitic resonance results from bending motion of the staves and can significantly decrease the radiated acoustic pressure and generate distortion. This work presents a multiple-degree-of-freedom lumped parameter model that captures both the breathing and bending resonances of the transducer and provides a more accurate prediction of its effective coupling coefficient. Results are compared with a one-degree-of-freedom model, finite element models, and experimental data. Modifications to account for internal volumes and nonlinear effects are also presented and discussed.
A statistical analysis of wind turbine A-weighted sound levels
Authors: Schomer Paul D. , Hessler George , Hessler David
Published: November 2013

Hessler and Hessler collected a two week database of wind turbine 10-min L-90 A-weighted levels in three orthogonal directions from an essentially solitary wind turbine (unit located at end of north-south row). These data have been analyzed statistically and this analysis shows that the wind turbine emissions during the day and at night form a clearly normal distribution with a mean level of 32 dB and standard deviation of 2.4 dB for daytime, 7 Am to 10 PM and a mean level of 36 dB and standard deviation of 2 dB, for nighttime, 11 PM to 5 AM. The nighttime hours were selected as the louder hours of the night when, presumably, an inversion was present. The statistical plots clearly show the data collected for wind turbine non-operation, the transition region between non-operation and full operation, the region of full turbine power, and the data that represent discreet noisier events. This result from a comprehensive, single survey suggests that it is necessary to analyze the noisier nighttime hours separately from daytime or the entire 24-h day, if one is to correctly predict or measure the noise during these critical nighttime hours.
Analysis of acoustic harmonic generation in a solid with multiple nonlinear interfaces
Authors: Biwa Shiro , Ishii Yosuke
Published: November 2013

Weak bonds and delaminations are typical examples of imperfect interfaces in multilayered structures. Nonlinear acoustic/ultrasonic methods are expected to offer a promising means to monitor these imperfect interfaces, as such interfaces behave nonlinearly when subjected to high-amplitude waves and result in the occurrence of nonlinear frequency components such as higher harmonics. Harmonic generation at a single nonlinear interface has been studied by many investigators from both theoretical and experimental points of view. In this presentation, a theoretical analysis of harmonic generation at multiple nonlinear interfaces is presented within a framework of one-dimensional elastic wave propagation in the frequency domain. The analysis is based on the perturbation expansion of the wave field by assuming the weak nonlinearity. Specifically, the second-harmonic generation is analyzed by first solving the linear transmission of the incident fundamental component, and then the propagation of the second-harmonic components generated at nonlinear interfaces. Some numerical results are demonstrated and compared to the results of time-domain analysis using the finite element method. The present analysis shows that harmonic generation in multilayered solids is remarkably frequency-dependent, as both the fundamental and the harmonic components interact with the layered structure in a complex manner.
Smart sonic detection and ranging for blind sources localization and separation
Authors: Wu Sean F. , Zhu Na
Published: November 2013

A new methodology for blind sources localization and separation in arbitrary three-dimensional space is presented. The underlying principle this methodology is the discrete short-time sonic detection and ranging (SODAR) [J. Acoust. Soc. Am. 133(6), 4054—4064 (2013)] that searches sound sources over discrete frequency-time regions in a systematic and automatic manner. For simplicity yet without loss of generality, only the dominant sound source within each discrete frequency-time region is considered. Once the search is completed, the frequency contents and time instances that correspond to the sound sources identified at the same coordinates are strung together and played back one by one. In this way, one can use N number of sensors to locate and separate S sources, where S can be much larger than N. Numerical simulations and experimental validations of using this methodology for locating and separating arbitrarily time-dependent sound sources in arbitrary three-dimensional space are demonstrated. Advantages and limitations of this methodology are discussed as well.
Acoustic radiation force. Part I: Finite element modeling for elastic objects
Authors: Abawi Ahmad T. , Kirsteins Ivars
Published: November 2013

The study of the acoustic radiation force produced by acoustic beams has been the topic of active research in the last few years mainly due to its ability for particle trapping and non-contact manipulations. However, efforts in modeling the radiation force have mainly focused on analytic solutions and thus have been limited to spherical objects, where the acoustic radiation force has been calculated for a plane wave as well as various types of beams. But up until recently, even those efforts were limited to using on-axis beams, where the incident beam is along an axis that goes through the center of the sphere and thus reduces the problem to an axially symmetric one. In this work we use the finite element technique to compute the acoustic radiation force for an arbitrary elastic object and for an arbitrary incident beam. One of the main objectives of this work is to understand and interpret the data we collected at a recent experiment we conducted at the Washington State University test tank facility, where a 2.5-in. PMMA sphere was ensonified by an intense amplitude-modulated ultrasound beam focused at its surface.