bluuebunny/crossref_metadata_2025 huggingface dataset:
Designing petrochemical plants to permit retrofitting of any additional controls needed to meet community noise limits.
Authors: Brittain Frank H.
Published: October 2013

Designing petrochemical, power, or industrial plants to meet community noise limits can be expensive. To meet stringent limits, incremental costs often exceed one million dollars per decibel. There is considerable uncertainty, including: overly conservative or unrepresentative vendor noise data, limitations of ray-tracing software, questionable accuracy beyond 1000 m, lack of TL and absorption data below 125 Hz, unreliable IL data for pipe lagging at all frequencies, unexpected operating conditions, and vendors not meeting their equipment noise limits. Atmospheric effects can cause variations of A-weighted community noise levels of 25 dB at 100 m from a refinery, which can make meeting a not-to-exceed noise limit difficult and risky. Further, lack of experience with noise control of any participant (noise control engineer, project, owner, regulators, or vendors) can substantially increase uncertainty. Including sufficient noise controls to cover these uncertainties will be expensive, often overly conservative, and often unnecessarily expensive. One way to substantially lower costs and risks is designing the plant to permit delaying some but not all controls until start-up—if needed. This paper describes the planning needed to permit a partial reliance on retrofit controls, what type of controls can be delayed until start-up, and space allocation. Examples are included.
On the fast arrivals seen in impulse propagation in the nocturnal boundary layer.
Authors: Blom Philip , Waxler Roger
Published: October 2013

On clear dry nights over flat land, an acoustic duct forms in the atmospheric boundary layer. The duct is formed by a temperature inversion in the lowest few hundred m of the atmosphere and by the stiff wind, known as the nocturnal jet, which commonly develops above the temperature inversion. An impulsive signal undergoes strong dispersion as it propagates in the nocturnal duct and is received at long ranges from the source as an extended wave train consisting of a series of distinct arrivals followed finally by a low frequency tail. The first arrival is of interest here. Through its interaction with the nocturnal jet, the first arrival is often anomalously fast. Accompanying the increased propagation speed is a marked decrease in amplitude. It will be shown that an explanation for this behavior is given by geometrical acoustics.
Investigation of dominant sources of pressure fluctuations and infrasonic wind noise in microphones.
Authors: Abbott John Paul , Raspet Richard , Webster Jeremy , Yu Jiao
Published: October 2013

Investigation of the time dependent relationship between the vertical wind velocity fluctuations and the pressure sensed on the ground as measured in an open field is done to determine if the turbulence-shear term of the Poisson equation is the dominant source of pressure fluctuations and infrasonic wind noise present in microphones, or some other source. The wind velocity was measured using a three-axis ultrasonic anemometer and six one-dimensional ultrasonic anemometers. The pressure was measured simultaneously using two half-inch free-field pressure microphones, one placed flush with the ground, the other at a height of 1 m above the first. The anemometers were also situated above and adjacent to the microphones. The three axis anemometer was set at a height of 1 m, and the six, one-dimensional anemometers, as a vertical array from a height of 0.1–2 m above the ground. As this is still an ongoing investigation, only a description of the experiment and the current findings are presented and discussed.
New models for wind noise measured in a flat surface under turbulent flow.
Authors: Yu Jiao , Raspet Richard , Webster Jeremy , Abbott JohnPaul
Published: October 2013

We have previously developed models for predicting the power spectral density of the wind noise pressure measured in a flat plate outdoors from the measured power spectral density of the turbulence and the measured wind velocity profile above the plate [Yu et al., Proceedings of NCAD 2008, NoiseCon2008-ASME NCAD]. Recently we have corrected an error in the model for the logarithmic profile wind velocity gradient results and have developed an improved integration method. Also, we have developed a prediction for arbitrary wind velocity profiles using the previous single exponential model. Typical results comparing our predictions with our measurements are presented and analyzed. A simple algebraic fit to the prediction for the logarithmic profile fit form is also provided for use by others. [Research supported by the U.S. Army TACOM-ARDEC at Picatinny Arsenal, NJ.]
Spectral modulation detection training in older adults with hearing loss.
Authors: Sabin Andrew T. , Clark Cynthia A. , Eddins David A. , Dhar Sumitrajit , Wright Beverly A.
Published: October 2013

Individuals with hearing loss are poorer than normal-hearing listeners at detecting patterns of peaks and valleys of sound level spread across audio frequency (spectral modulation detection)—an important skill for speech and music perception. In this preliminary report we examined whether listeners with hearing loss could improve on spectral modulation detection with practice. We trained older adults with sensorineural hearing loss (n=7) ∼1 hr/day for 7 days to distinguish a 400–3200 Hz noiseband with a flat-spectrum from one with a 2 cyc/oct sinusoidal spectral modulation. Modulation depth was varied adaptively to determine the detection threshold. Their mean thresholds improved significantly from 18.9 to 12.8 dB. These listeners also improved at both a lower and a higher untrained spectral modulation frequency (1 and 4 cyc/oct), but showed no change on a measure of frequency selectivity. Interestingly, a separate group of younger normal-hearing adults who received the same training (n=7) did not improve on the trained (6.9 to 6.6 dB) or untrained conditions. Normal-hearing listeners had lower pre-training thresholds than individuals with hearing loss, and across all listeners the magnitude of individual improvement was correlated to pre-training threshold (r=0.92). Listener age and/or hearing loss could have contributed to these across-population differences.
Multidimensional perceptual scaling of musical timbre by hearing-impaired listeners.
Authors: Fitz Kelly , Burk Matt , McKinney Martin
Published: October 2013

We examine the impact of hearing loss and hearing aid processing on the perception of musical timbre. Our objective is to identify significant timbre cues for hearing-impaired listeners, and to assess the impact of hearing aid signal processing on timbre perception. Hearing aids perform dynamic, level-dependent spectrum shaping that may influence listeners’ perception of musical instrument timbres and their ability to discriminate among them. Grey [“Multidimensional perceptual scaling of musical timbres,” J. Acoust. Soc. Am. 61, 1270 (1977)] showed that sustaining instrument tones equalized for level, loudness, and duration are distinguished primarily along three perceptual dimensions that are strongly correlated with the acoustical dimensions of: (1) spectral energy distribution, (2) spectral fluctuation, and (3) precedent high-frequency, low-amplitude energy. Following the work of Grey, we ask listeners having mild to moderately severe sensorineural hearing loss to rate pairs of synthetic musical instrument tones according to dissimilarity in aided and unaided conditions. We analyze the dissimilarity judgments to identify acoustical correlates for the significant dimensions of timbre discrimination. This analysis helps us to objectively estimate the impact of hearing aid signal processing on the ability of hearing-impaired listeners to discriminate among musical instruments, an important component of musical listening.
Scan-based near-field acoustical holography on partially correlated fields: Theory and numerical experiments.
Authors: Gardner Michael D. , Gee Kent L. , Wall Alan T. , Sommerfeldt Scott D. , Manwill Daniel , Blotter Jonathan D.
Published: October 2013

Conventional near-field acoustical holography (NAH) requires a coherent field. For a coherent source, a scan-based approach can be used with one reference microphone to stitch the phase. For a noncoherent field, scan-based NAH can be performed if the virtual coherence technique is used. This technique uses multiple reference microphones to decompose the partial field into mutually uncorrelated partial fields, which are then processed by some NAH method. In particular, the statistically optimized near-field acoustical holography (SONAH) method is used with modified Tikhonov regularization. Numerical experiments are performed on a series of point sources with source strengths chosen to mimic the source characteristics of high-powered jets. The experiments are designed to aid in determining the proper number and location of reference microphones for doing NAH work on high-powered jet noise. [Work supported by Blue Ridge Research and Consulting and the Air Force Research Laboratory.]
Scan-based near-field acoustical holography on partially correlated fields: Laboratory experiments.
Authors: W Alan T. , Gardner Michael D. , Gee Kent L. , Sommerfeldt Scott D. , Manwill Daniel , Blotter Jonathan D.
Published: October 2013

Forms of near-field acoustical holography (NAH) can be applied to source reconstructions of arbitrarily correlated extended sources, such as jet exhaust plumes. Prior to implementing NAH to reconstruct the jet noise source region of a military jet aircraft, laboratory experiments are being performed. These experiments utilize statistically optimized NAH (SONAH), coupled with the virtual coherence method, to reconstruct the radiation from correlated, partially correlated, and uncorrelated loudspeakers. Results from these experiments will be shown. Reconstructions of this type require the use of multiple reference microphones. However, little is known about how many should be used or where they should be placed. Successful reference placement strategies are being explored and commentary on these results will also be given. [Work supported by Blue Ridge Research and Consulting and the Air Force Research Laboratory.]
Limiting performance of active vibration compensation in free multi-degree-of-freedom mechanical systems.
Authors: Ryaboy Vyacheslav
Published: October 2013

Examples of free (not supported) mechanical system requiring active vibration control range from space structures to vibration-isolated platforms for sensitive equipment. While active damping systems reducing resonance vibrations of the structure received significant attention and reached practical implementation, active vibration compensation, or cancellation of forced vibration, is still problematic in complex systems. In this work, active vibration compensation is considered in frame of limiting performance approach that aims at estimating the best results attainable in the whole class of linear multi-degree-of-freedom systems. Several design goals are considered, including absolute and relative displacements of various points of the system. The resulting estimates are valid for all possible sets of internal active forces. The limiting performance is estimated in terms of frequency domain and work performed by active forces on system displacements, which is considered a measure of the control effort. These estimates are expressed as exact inequalities in explicit analytical form. Active force distributions emerging from limiting performance analyses can assist in finding rational system configurations and optimal controls. Minimum active work, expressed in terms of passive subsystem parameters, provide a criterion for optimization of a structure as a potential host for an active vibration control system.
Source-filter interaction in the opposite direction: Subglottal coupling and the influence of vocal fold mechanics on vowel spectra during the closed phase.
Authors: Lulich Steven M. , Zanartu Matias , Mehta Daryush D. , Hillman Robert E.
Published: October 2013

Studies of speech source-filter interaction usually investigate the effect of the speech transfer function (loading) on vocal fold vibration and the voice source. In this study we explore how vocal fold mechanics affect the transfer function throughout the glottal cycle, with emphasis on the closed phase. Coupling between the subglottal and supraglottal airways is modulated by the laryngeal impedance. Although coupling is generally thought to occur only during the open phase of vocal fold vibration, a posterior glottal opening and the vocal fold tissue itself can allow sound transmission, thereby introducing coupling during the closed phase as well. The impedance of the vocal fold tissue at closure is shown to be small enough to permit coupling throughout the phonatory cycle, even in the absence of a posterior glottal opening. Open- and closed-phase coupling is characterized using mathematical models of the subglottal and supraglottal airways, and the parallel laryngeal impedances of the membranous glottis, posterior glottal opening, and vocal fold tissue. Examples from sustained vowels are presented, using synchronous recordings of neck skin acceleration, laryngeal high-speed videoendoscopy, electroglottography, and radiated acoustic pressure.
Analysis and synthesis of humpback whale songs.
Authors: Dhar Pranab K. , Cho Sangjin , Kim Jong-Myon , Chong Uipil
Published: October 2013

The humpback whale song is one of the most complex, non-human, acoustic displays in the animal kingdom. In this paper, we analyze and synthesize the humpback song using additive synthesis which is one of the most powerful techniques for the analysis, modification, and synthesis of complex audio or speech signals. This method creates complex sounds by adding together individual sinusoidal signals called “partials.” A partial’s frequency and amplitude are each time-varying functions, so it is a more flexible version of the harmonic associated with a Fourier series decomposition of a periodic waveform. Applying the fast Fourier transform to all overlapping frames (small time segments), we can detect peaks from the frequency spectrum of each frame and calculate the frequency, magnitude, and phase for all the peaks. These extracted parameters are then used as components of the sinusoidal signals (partials) for the synthesis process. This process finally reconstructs and concatenates each frame, generating the synthesized humpback song. We observed that this synthesized song resembles much more closely the original humpback song by the time/frequency domain representation and listening. In the future, we will analyze and synthesis other baleen whale songs with this powerful synthesis method. [Work supported by IITA (IITA-2008-(C1090-0801-0039)).]
Acoustics in granular porous media and the consolidation continuum.
Authors: Berryman James G.
Published: October 2013

One key influence on acoustic wave propagation in granular porous media is the degree to which the solid constituent grains can be treated as fully consolidated, weakly and/or partially consolidated, or entirely unconsolidated. Well-known results of Gassmann and Biot all implicitly assume that the medium is fully consolidated, with welded contacts at the grain-to-grain interfaces. Such implicit assumptions are also present in standard bounding methods for elastic behavior, such as the Hashin-Shtrikman bounds of elasticity. Influence of reductions in the degree of consolidation can be quantified for partially or weakly consolidated media, and granular media having no welded contacts can also be treated as porous media for sound waves in the Biot-Gassmann sense when grains are experiencing sufficient overall confining stress. Methods recently developed to quantify wave propagation characteristics over the full range of possible behaviors in grain packs, as well as comparisons to experiments, will be presented.
Model parameter estimation of a porous seabed using in situ acoustic-probe and chirp-sonar reflection data.
Authors: Turgut Altan
Published: October 2013

The velocity dispersion and frequency dependency of attenuation in marine sediments are two important measures that provide the ability to test the validity of geoacoustic models as well as to estimate physical properties from the acoustic data. A widely-used Biot–Stoll theory for elastic-wave propagation in porous marine sediments seems to predict a narrow band of dispersion that was measured only in well-sorted granular marine sediments [A. Turgut and T. Yamamoto, J. Acoust. Soc. Am. 87, 2376–2382 (1990)]. Recent measurements in silty-sand sediments show almost linear frequency dependency of attenuation and mild velocity dispersion within the 3–80 kHz frequency band. The newly measured attenuation and velocity dispersion curves are in good agreement with those predicted by an extended Biot theory for sediments with a distribution of pore sizes [T. Yamamoto and A. Turgut, J. Acoust. Soc. Am. 83, 1744–1751 (1988)]. Simultaneous measurements of in situ acoustic-probe data and chirp-sonar reflection data are also used to estimate the model parameters of the extended Biot model. [Work supported by the Office of Naval Research.]
Cancellous bone as a poroelastic medium: Extracting underlying material properties from improved ultrasonic measurements of frequency dependent attenuation and phase velocity.
Authors: Miller James G. , Anderson Christian C. , Bauer Adam Q. , Marutyan Karen , Bretthorst G. Larry , Holland Mark R. , Hoffmeister Brent K. , Wear Keith A.
Published: October 2013

Cancellous bone can be modeled as a poroelastic medium consisting of a viscous fluid (marrow) and a stiff framework (trabeculae). Transmission of ultrasound through bone can result in fast and slow waves as well as mode conversion and multiple scattering, all of which can mask the underlying material properties of bone that determine fracture risk. Phase cancellation at the receiving transducer and interference effects in the field can further compromise the potential of bone sonometry for assessing bone quality. The attenuation coefficient is observed to increase approximately linearly with frequency, a fact that accounts for the use of broadband ultrasound attenuation (BUA) to characterize bone. Many laboratories report that the phase velocity of ultrasonic waves propagating through cancellous bone decreases with increasing frequency (negative dispersion). However, an increase in phase velocity with frequency (positive dispersion) would be expected based on the causality-imposed Kramers–Kronig relations. This apparent negative dispersion in bone can arise from interference between fast wave and slow wave longitudinal modes. Interference and phase cancellation at the receiver can also be sources of artifactual alterations in the attenuation and phase velocity. [Work supported in part by NIH R37HL40302 R01AR057433, NSF CBET-0717830].
Successful use of Bayesian inference to obtain the fast and slow wave properties of cancellous bone from sonometry measurements.
Authors: Anderson Christian C. , Pakula Michal , Laugier Pascal , Bauer Adam Q. , Marutyan Karen , Bretthorst G. Larry , Holland Mark R. , Miller James G.
Published: October 2013

Clinical trials have demonstrated that frequency dependent attenuation [broadband ultrasound attenuation, (BUA)] and speed of sound (SOS) provide an assessment of fracture risk. Previous studies from our laboratory of the “forward problem” show that the negative dispersion observed in cancellous bone can arise when signals consisting of overlapped fast and slow waves are analyzed as if only one wave is present. The present study examines the “inverse problem” using Bayesian probability methods suitable for recovering the underlying material properties from received transmission sonometry signals complicated by the presence of multiple signals. Transmission studies were carried out on bone mimicking phantoms and on specimens of femur condyles. Received rf signals served as input to our Bayesian algorithm. The program that implements the Bayesian calculations reconstructs the individual fast and slow waves and constructs the model output from parameters that maximize the joint posterior probability. Composite rf signals constructed by summing these waves were in excellent agreement with signals transmitted through bone-mimicking phantoms and were in good agreement with signals transmitted through bone samples despite the additional complexities arising from ultrasound propagation through the complex trabecular network. [Work supported in part by NIH R37HL40302 R01AR057433, and NSF CBET-0717830].
Measurements and modeling of midfrequency clutter from fish aggregations over Georges Bank in the Gulf of Maine.
Authors: Gauss Roger C. , Fialkowski Joseph M. , Menis Richard , Kunz Edward L. , Stanton Timothy K. , Sellers Cynthia J. , Jech J. Michael
Published: October 2013

Broadband midfrequency acoustic measurements of fish backscattering were made with two complementary sonar systems in September 2008 at the northern slopes of Georges Bank in the Gulf of Maine. One system, towed near the surface, was downward-looking (short-range: < 0.2 km) and was used to image fish at high vertical resolution throughout the water column. The other system was horizontal-looking (relatively long-range: 1–10 km), consisting of a vertical source array and a horizontal receive array, and was used to image fish at high horizontal resolution. In this talk, the focus is on characterizing the longer-range data. Spectrogram analysis showed that the echoes had resonance frequencies in the 2–4 kHz band, consistent with scattering by Atlantic herring, while examination of normalized match-filter output revealed strong, spatiotemporally variable clutter. The associated probability-density functions (PDFs) exhibited variable non-Rayleigh behavior. Several PDF models were fit to the data, with the K and Poisson-Rayleigh PDF models providing not only good fits, but physical insights into the clutter process (such as estimates of the expected number of discrete scatterers per unit area). These results provide an improved understanding of both fish behavior and the characteristics of fish aggregations as long-range clutter fields. [Work supported by ONR.]
Statistics of echoes from a directional sonar beam insonifying finite numbers of single scatterers and patches of scatterers.
Authors: Chu Dezhang , Stanton Timothy K.
Published: October 2013

When a sonar beam sweeps across a field of scatterers, the echoes can fluctuate significantly from ping to ping. The fluctuations can be strongly non-Rayleigh because: (1) there can be a small number of scatterers in the beam; (2) the distribution of scatterers can be inhomogeneous or “patchy;” and (3) the echoes are weighted by the nonuniform response of the sonar beam. In this paper, a general formulation combining equations derived by Ehrenberg [Proc. Conf. Eng. Ocean Environ. 1, 61–64, (1972)] and Barakat [Optica Acta 21, 903–921, (1974)] is developed to account for a directional sonar beam involving an arbitrary finite number of scatterers, each with an arbitrary echo probably density function (PDF) and randomly located in the beam. Theoretical predictions are made, along with numerical simulations for validation, for a range of conditions, including: (1) different number of scatterers arbitrarily located in the beam and (2) different echo PDFs of the scatterers. Here, a “scatterer” could be an individual or a patch of scatterers whose dimensions are much smaller than the footprint of the sonar beam. Although the application is intended for volumetric patches, the formulation could be applied to areal patches under appropriate conditions. [Work supported by ONR.]
Comprehensive, integrated database of elements contributing to bottom and volume clutter.
Authors: Vigness-Raposa Kathleen J. , Ellison William T. , Frankel Adam S. , Zeddies David , Schroeder Cheryl L. , August Peter V. , Damon Christopher , LaBash Charles
Published: October 2013

Multiple components within and at the bottom of the water column can scatter acoustic signals, resulting in decreased sonar performance and compromised tactical decision making. Many of the biological organisms that contribute to acoustic clutter are also protected or managed species, integral to a fully functional marine ecosystem. In order to understand, predict, and model bottom and volume scattering, detailed descriptions of the spatial, spectral, and temporal variability of clutter elements are needed, along with reliable estimates of backscattering strength. All of these necessary components are dependent on marine wildlife databases. Efforts by several organizations have resulted in databases that provide pieces of the overall puzzle. Databases of distribution and abundance (Census of Marine Life’s OBIS-SEAMAP), two-dimensional movement (Census of Marine Life’s Tagging of Pacific Pelagics), and diving and movement behavior (Marine Wildlife Behavior Database) are examples of current, but disparate, projects. Ongoing efforts are consolidating inputs from such databases to predict realistic, spatially dependent bioclutter animats. By linking geospatial features of clutter elements in training and mission planning systems, sonar operators and designers can better predict and analyze the occurrence of target-like clutter. [Work supported by NAVSEA SBIR, ONR STTR, and NOAA.]
Experimental tests of models for high-frequency scattered envelope statistics.
Authors: Lyons Anthony
Published: October 2013

There has been, in general, a lack of quantitative comparison between high-frequency physics-based clutter model predictions and experimental data due mainly to difficulties in performing well-controlled at-sea experiments and obtaining necessary ground truth. To address this shortfall, experiments have been performed over the past 5 yrs to gather data with which to confront recently developed physics-based clutter models. The experimental data sets were obtained during experiments conducted off of Elba Island, Italy in May 2003 and at Seneca Lake, New York, in the summers of 2005 and 2006. Colocated high-frequency, broadband acoustic data and high-resolution environmental ground truth data were collected as part of these experiments. In all cases comparisons between model predictions and measured data showed promising similarities in K-distribution shape parameter estimates and their dependence on bandwidth, grazing angle, and seafloor type. The favorable model/data comparisons show that it is possible to link the scattered envelope distribution to measurable environmental properties, providing the foundation necessary for solving several important problems related to the detection of targets in non-Rayleigh clutter including performance prediction for different systems based on seafloor properties and extrapolation of performance to other systems and bandwidths.
Felt panels for an art space.
Authors: Newcomb Jessamyn A.
Published: October 2013

The art building on Virginia Tech’s campus is an adaptive reuse project. Despite its current function, the transformation of the space has left it acoustically ill suited for class instruction. This research focuses on absorption of specific frequencies through the use of felt panels to reduce noise and increase speech intelligibility for class instruction. Microperforated panels are proposed as a solution due to their simple structures and predictable wide-band absorption characteristics. Benefits will be quantified by measuring pink noise decay in the building pre- and postpanel installation.
Absorption coefficients part 1: Is square area enough?
Authors: Sauro Ron , Vargas Michael , Mange Gary
Published: October 2013

Attempting to correlate the measurements of absorption coefficients in ASTM-C423, ISO-354, and ISO-17497-1, it was observed that the results were varying to a large degree. An experiment was set up with 1 in., 6 lb density fiberglass panels having different shapes, sizes, and parameters. The shapes, sizes, and parameters of the panels are described in this paper. The types of experiments are also described along with the process that was used based on input from many of the members of the industry. The end results and conclusions are described in a paper titled “Absorption coefficients part 2: Is “edge effect” more important than expected?”
Architectural acoustics: Short course presentation material.
Authors: Hoover K. Anthony
Published: October 2013

The Technical Committee on Architectural Acoustics (TCAA) is a Registered Provider in the American Institute of Architects (AIA) Continuing Education System (CES). The TCAA has developed a standardized introductory short course for architects, called “Architectural Acoustics.” An architect can earn one continuing education unit (CEU) by attending this short course, if it is presented by a qualified member of TCAA. The course covers topics in sound isolation, mechanical system noise control, and finish treatments. This paper will cover the course material in order to prepare and qualify potential presenters. There will be time at the end of the paper for questions and answers on the course material. In order to qualify as an authorized presenter for this AIA/CES short course, attendance at this workshop and membership in TCAA are required.
Detecting humpback whale sounds in the Bering Sea: Confounding sounds in a cacophony of noise.
Authors: Heimlich Sara L. , Mellinger David K. , Nieukirk Sharon L. , Klinck Holger , Stafford Kate , Moore Sue E. , Stabeno Phyllis J.
Published: October 2013

Humpback whales (Megaptera novaeangliae) are top predators of large zooplankton and forage fish, and one of the most common large whales in the Bering Sea. While present on feeding grounds, humpback whales produce nonsong sounds probably associated with feeding or social contacts. However, little is known about these highly variable sounds, and their detection is challenging. Recordings were collected during 2006–2007 at the long-term oceanographic moorings M2, M4, and M5 in the eastern Bering Sea. Passive acoustic detection of humpback whale calls in these recordings was confounded by a variety of other sounds, which fall within the same parameters as nonsong humpback vocalizations. An automatic algorithm that detects tonal sounds in the 300–950 Hz frequency band was used to find humpback calls. Raw detections were visually examined to verify the accuracy of the detections. This algorithm resulted in a significant number of wrong detections (false positives), especially sounds of bearded seals (Erignathus barbatus) and bowhead whales (Balaena mysticetus). An error rate was calculated to correct the high number of false detections, and further refinements were made to the automatic detection algorithm. The problems and possible solutions to detecting humpback whale sounds in complex acoustic recordings will be presented.
Monitoring cetaceans on seamounts in the Azores using passive acoustic techniques.
Authors: Cascäo Irma , Lammers Marc O. , Silva Monica A. , Afonso Pedro , Prieto Rui , Santos Ricardo S.
Published: October 2013

Seamounts are hotspots of marine life in the Azores, acting as feeding stations for diverse top predators, including cetaceans. Long-term monitoring of remote marine ecosystems is logistically difficult and expensive, involving high costs in terms of ship time and human resources, as well as being reliant on sea conditions. Passive acoustic methods are a highly efficient monitoring technique to study the distribution or abundance of vocalizing cetacean species. In 2007, we began to deploy Ecological Acoustic Recorders (EARs)—two shallow (35 m) and two deep (190 m) units—around seamounts to explore and monitor the occurrence of cetaceans, their temporal patterns, and changing levels of activity. A wide variety of time series acoustic signals were collected, revealing the presence of different species of cetaceans and specific associations between species, based on their vocalization characteristics. Detections of vessels are being used to determine levels of activity at one of the study sites, Formigas bank marine reserve, making the EAR a useful tool to monitor protected areas. The EARs are an effective ecological instrument for monitoring cetaceans year-round and will provide a better understanding of the influence of seamounts on cetaceans’ behavior.
Interaction of single biological cell with tandem microbubbles in microfluidics.
Authors: Sankin Georgy , Yuan Fang , Zhong Pei
Published: October 2013

Coupled oscillation of two laser generated microbubbles (maximum radius = 28 μm) and associated shear stresses are investigated experimentally. Bubble-bubble interaction in a microchannel of 25 μm height is observed using high-speed video cameras and μPIV technique. Two liquid microjets moving in opposite directions can be generated when the second bubble is produced at the maximum size of the first one. The interaction of these tandem microbubbles with single cell leads to controllable poration of adjacent cell membrane and dye uptake. μPIV data are compared with cell viability at various bubble-cell distances and azimuthal orientations. This method provides a new approach for highly selective cell treatment in situ, applicable to targeted microinjection of macromolecules and gene vectors in microfluidics devices. [Work supported in part by NIH.]
Histotrispy: Urologic applications.
Authors: Roberts William W. , Hall Timothy L. , Hempel Christopher R. , Xu Zhen , Fowlkes J. Brian , Cain Charles A.
Published: October 2013

Histotripsy is an extracorporeal ablative technology that utilizes microsecond pulses of intense ultrasound to produce nonthermal, mechanical fractionation of targeted tissue. We have previously demonstrated the feasibility of histotripsy ablation in in vivo renal and prostate models. We sought to assess the chronic tissue response, tolerability, and safety of prostate histotripsy in a chronic in vivo canine model. Five acute and thirteen chronic canine subjects were anesthetized and treated with histotripsy targeting the prostate. Pulses consisting of three cycle bursts of 750-kHz ultrasound at a repetition rate of 300 Hz were delivered from a highly focused 15-cm aperture array. Prostates were harvested at 0, 7, 28, or 56 days after treatment. Transrectal ultrasound imaging provided accurate targeting and real-time monitoring of histotripsy treatment. Consistent mechanical tissue fractionation and debulking of prostate tissue was seen acutely and at delayed time points without collateral injury. Canine subjects tolerated histotripsy with minimal hematuria or discomfort. Only mild transient lab abnormalities were noted. Histotripsy is a promising noninvasive therapy for prostate tissue fractionation and debulking that appears safe and well tolerated without systemic side effects in the canine model.
Improving efficiency of ultrasound histotripsy sources by transmitting at the second harmonic frequency.
Authors: Bigelow Timothy A.
Published: October 2013

Therapeutic ultrasound has shown potential for improving many aspects of medical care in recent years. Therapeutic ultrasound often involves high pressures or intensities, but pressures and intensities in tissue are limited by nonlinear propagation. The impact of nonlinear propagation is most severe for therapies involving cavitation where the peak rarefactional pressure plays the dominate role. As a result, in applications such as histotripsy, the size and power of the ultrasound source must be significantly increased in order to obtain the pressures needed in vivo. In this study, a new ultrasound source design was developed that will help mitigate the effects of nonlinear propagation. Specifically, sound was transmitted at both the fundamental and the second harmonic with the amplitude and phase of the second harmonic designed to counter nonlinear propagation effects for varying source powers from 10 to 500 W. The simulations demonstrated a 30% increase in the peak rarefactional pressure relative to a source where only the fundamental was transmitted when the appropriate phase was used for the second harmonic.
Skull flexure from blast waves: A mechanism for brain injury with implications for helmet design.
Authors: Moss William C. , King Michael J. , Blackman Eric G.
Published: October 2013

Traumatic brain injury [TBI] has become a signature injury of current military conflicts. The debilitating effects of TBI are long-lasting and costly. Although the mechanisms by which impacts cause TBI have been well researched, the mechanisms by which blasts cause TBI are not understood. Various possibilities have been investigated, but blast-induced deformation of the skull has been neglected. From numerical hydrodynamic simulations, we have discovered that nonlethal blasts can induce sufficient flexure of the skull to generate potentially damaging loads in the brain, even if no impact occurs. The possibility that this mechanism may contribute to TBI has implications for the diagnosis of soldiers and the design of protective equipment such as helmets. [This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344].
Guided waves analysis using multiemitter and multireceiver arrays.
Authors: Minonzio Jean-Gabriel , Talmant Marilyne , Laugier Pascal
Published: October 2013

Structural and material properties of elastic waveguides can be characterized by fitting measured to theoretical guided wave phase velocities. Here emitters and receivers are placed in contact on the same side of the waveguide (i.e., axial transmission geometry). Multireceiver arrays allow the determination of phase velocities using two-dimensional spatial-temporal Fourier transform, which requires a large distance probed by the receivers. Practical constraints, as in clinical inspection of cortical bones, may reduce the inspected spatial length and therefore the efficiency of this technique. We propose a technique which takes benefit of using both multiple emitters and multiple receivers. This approach derived from the DORT method adapted to the transmission problem. The singular values decomposition at different frequencies of the transmission matrix between the arrays give the invariants of transmission, which are linked with the guided modes. First, experiments carried out on different metallic plates are shown. Experimental velocities are in good agreement with Lamb waves theoretical values. In particular, zero group velocity resonance and negative phase velocities are shown. These results allows a good evaluation of the thickness and the transverse and longitudinal bulk waves velocities. Further applications concerning evaluation of elastic properties of cortical bone are finally mentioned.
Auditory attention and the active listener.
Authors: Shinn-Cunningham Barbara
Published: October 2013

Traditionally, psychoacousticians and auditory physiologists have focused on how stimulus properties affect perceptual abilities, measuring just-detectable differences in different acoustic attributes or thresholds for audibility of different sounds. However, in everyday settings with more than one audible sound source, these low-level abilities are often not the factors limiting understanding of an important sound source. Instead, the way the brain organizes sound and focuses attention has an enormous impact on what we actually hear and analyze out of an auditory scene. Recent studies in both perceptual and physiological acoustics are working to uncover how the intentions and goals of the listener influence processing of sound in the brain. This talk will review some recent advances in auditory neuroscience that demonstrate the importance of top-down attention on neural processing and perception of sound.
Hot topics of signal processing in acoustics.
Authors: Xiang Ning , Chambers David
Published: October 2013

Signal processing is used to some extent in all areas of acoustics, such as extracting relevant information from acoustic measurements made either in the laboratory or in the field, processing signals and/or synthesizing data to cope with demanding tasks raised in acoustics. Techniques range from simple classical approaches based on Fourier transforms and Gaussian noise, to sophisticated model-based techniques that incorporate physical/parametric models of the acoustical system. In this paper we highlight new approaches to signal processing that could be applied to a broad variety of acoustical problems. These include coded signals for architectural-acoustics, acoustical communications, and medium characterization, Bayesian methods for room acoustics, physical acoustics, and underwater acoustics including highly nonlinear problems with non-Gaussian noise, and extensions to the familiar Kalman filtering to nonlinear models. Examples of each approach will be shown that illustrate the advantages and disadvantages of each technique. Additional topics may be discussed as time allows.
Tuning and tone quality of bagpipe drones.
Authors: Ayers R. Dean , Nordquist Peter R.
Published: October 2013

Tunes are played on the Great Highland bagpipe using the tone holes of its conical chanter. The much quieter practice chanter has holes with the same spacings on a narrow cylindrical bore. Differences between spherical waves in a cone and plane waves in a cylinder give rise to striking differences in pitch and tone quality. Drone pipes do not need to fit into either the conical family or the closed-pipe family of reed woodwinds, because each drone produces only one note. A bass drone has three cylindrical segments, with diameters that increase in sequence, followed by an expansion chamber (bell and constricting cap) at the output end. Tuning slides between the cylinders create two additional expansion chambers with large diameters and adjustable lengths. (A tenor drone has two cylinders and one tuning slide.) Sound waves incident from either direction experience strong reflections at each jump in diameter, resulting in uneven standing waves and irregular input impedance curves that would be impractical for pipes with tone holes. Experimental results and computer models are used to relate the shape of a drone’s air column to its tuning and tone quality. [Work supported by the Paul S. Veneklasen Research Foundation.]
The influence of grain structures on resonance behavior near phase transitions.
Authors: Darling Timothy W. , Kaplan Gunes , TenCate James A. , McKnight Ruth E. A. , Carpenter Michael A.
Published: October 2013

Inhomogeneities such as grains or plastically deformed regions in materials locally change sound wave velocities and introduce scatter in the pattern of expected resonance frequencies. The accompanying variation in the components of the free energy may promote, or block, nucleation and growth of new phases near transition temperatures. Lanthanides and martensites are two groups of materials with complex phase structures where control of the phase transformation is important in technological applications. Complex oxide minerals with a wide variety of phase structures are important in understanding the behavior of the earth’s crust. The influence on mechanical resonances of both the micro (meso) structures and the appearance and growth of phases near transition temperatures will be discussed. Experimental data on resonance behavior in inhomogeneous materials (largely lanthanides, transition metals, and silicates), where attempts have been made to control the scale and type of microstructure as they approach phase transitions will be presented. [This work receives support from DOE Grant No. DE-FC52-06NA27616 through the University of Nevada Terawatt Facility.]
Temperature variation of Young’s modulus and elastic wave speed in a mixture of solid-particles in liquid.
Authors: Tavossi Hasson M.
Published: October 2013

The variation of ultrasonic wave speed in the solid-liquid mixtures as a function of temperature is studied. The goal of this investigation is to determine temperature dependence of the elastic moduli of materials consisting of different size solid particles. The elastic wave speed in solids is assumed to be proportional to the square root of Young’s modulus of the material. Elastic wave speed in the material is related to the variation of Young’s modulus of the solid constituents. Also considered are temperature dependence of the wave attenuation, by scattering and absorption, and the effects of phonon modes, their amplitude and frequency, on the elastic moduli and wave dispersion in the material. Previous experimental data have shown a decrease in elastic moduli at the contact points of solid particles with increase in elastic wave frequency. Findings on the variations of elastic wave speed in solids with temperature and frequency are compared to analyze any similarity between the effect of wave frequency increase and temperature increase.
Phonetic experience with specific words affects categorical perception of those words.
Authors: VanDam Mark , Port Robert F.
Published: October 2013

How does experience with specific words influence linguistic-phonetic categories? Listeners were trained over a five-session, listen-and-repeat task on a set of target words embedded in continuous speech and altered so that the initial stop consonant voice-onset time (VOT) was 80% longer than natural. Voicing boundaries were estimated before and after training using a two-alternative, forced-choice perceptual task on an eight-step VOT continuum. Stimuli were highly natural tokens by two stimulus talkers. Part 1 of the experiment asked whether exposure to lengthened forms would influence location of the voicing boundary, and, if so, whether that effect would generalize to similar forms. Results showed longer boundaries after exposure to lengthened VOTs for the trained forms, but lengthening did not generalize to new forms. Part 2 investigated voicing boundary locations as a function of lexical status (word, nonword) and usage frequency (high, low). Boundary locations indicated expanded VOT regions both for nonwords over words (opposite to the Ganong effect) and for high-frequency words over low-frequency words; neither lexical status nor usage frequency interacted with training. Results suggest a lexical sensitivity to low-level speech cues, thus offering support for a rich memory language model.
Duration and context speech rate as cues to lexical perception and word segmentation.
Authors: Henry Molly J. , Dilley Laura C. , Vinke Louis N. , Weinland Christopher J.
Published: October 2013

Duration and speech rate are traditionally assumed to be filtered out before lexical lookup takes place, although these factors are known to influence phoneme perception. Here, the hypothesis was investigated that duration can affect both perceived lexical identity, as well as the perceived number and implied locations of word boundaries relative to the speech signal. Experiment 1 was a production study which investigated durations of vocalic portions of phonetically similar versions of target word strings which differed in their number of syllables (e.g., cease versus see us); these target word strings were spoken in semantically neutral context sentences. As expected, vocalic durations in target strings with fewer syllables were shorter than those with more syllables. In Experiment 2, the relative durations of vocalic portions of target strings in sentences from Experiment 1, as well as sentential context speech rate, were manipulated using speech resynthesis. Relative duration and context speech rate both affected the words that participants heard, as well as the implied number of phonemes and imputed locations of word boundaries. These findings indicate that duration plays a significant and underinvestigated role in spoken word recognition and word segmentation.