bluuebunny/crossref_metadata_2025 huggingface dataset:
Overview of reverberation measurements in Target and Reverberation Experiment 2013
Authors: Yang Jie , Tang Dajun , Hefner Brian T. , Williams Kevin L. , Preston John R.
Published: October 2014

The Target and REverberation EXperiment 2013 (TREX13) was carried out off the coast of Panama City, Florida, from 22 April to 16 May, 2013. Two fixed-source/fixed-receiver acoustic systems were used to measure reverberation over time under diverse environmental conditions, allowing study of reverberation level (RL) dependence on bottom composition, sea surface conditions, and water column properties. Beamformed RL data are categorized to facilitate studies emphasizing (1) bottom reverberation; (2) sea surface impact; (3) biological impact; and (4) target echo. This presentation is an overview of RL over the entire experiment, summarizing major observations and providing a road map and suitable data sets for follow-up efforts on model/data comparisons. Emphasis will be placed on the dependence of RL on local geoacoustic properties and sea surface conditions. [Work supported by ONR.]
Non-stationary reverberation observations from the shallow water TREX13 reverberation experiments using the FORA triplet array
Authors: Preston John R. , Abraham Douglas A. , Yang Jie
Published: October 2014

A large experimental effort called TREX13 was conducted in April-May 2013 off Panama City, Florida. As part of this effort, reverberation and clutter measurements were taken in a fixed-fixed configuration in very shallow water (~20 m) over a 22 day period. Results are presented characterizing reverberation, clutter and noise in the 1800-5000 Hz band. The received data are taken from the triplet sub-aperture of the Five Octave Research Array (FORA). The array was fixed 2 m off the sea floor and data were passed to a nearby moored ship (the R/V Sharp). An ITC 2015 source transducer was fixed 1.1 m off the seafloor nearby. Pulses comprised of gated CWs and LFMs were used in this study. Matched filtered polar plots of the reverberation and clutter are presented using the FORA triplet beamformer. There are clear indications of biologic scattering. Some of the nearby shipwrecks are clearly visible in the clutter, as are reflections from a DRDC air-filled hose. The noise data show a surprising amount of time-dependent anisotropy. Some statistical characterization of these various components of the reverberation are presented using K-distribution based algorithms to note differences in the estimated shape parameter. Help from the Applied Physics Laboratory at the University of Washington was crucial to this effort. [Work supported by ONR code 322OA.]
Propagation measurement using source tow and moored vertical line arrays during TREX13
Authors: Hodgkiss William S. , Ensberg David , Tang Dajun
Published: October 2014

The objective of TREX13 (Target and Reverberation EXperiment 2013) is to investigate shallow water reverberation by concurrently measuring propagation, local backscatter, and reverberation, as well as sufficient environmental parameters needed to achieve unambiguous model/data comparison. During TREX13 the Marine Physical Laboratory (MPL) conducted propagation and forward scatter measurements. The MPL effort during TREX13 included deploying three, 32-element (0.2 m element spacing), vertical line arrays along the Main Reverberation Track at a bearing of ~128° and ranges ~2.4 km, ~4.2 km, and ~0.5 km from the R/V Sharp, where reverberation measurements were being made. In addition, MPL carried out repeated source tows in the band of 2–9 kHz along the Main Reverberation Track, using tonal and LFM waveforms. The experimental procedure is described and the resulting source-tow data is examined in the context of Transmission Loss and its implications for reverberation.
Acoustical Society of America Pioneers of Underwater Acoustics Medal: Michael B. Porter
Authors: Kuperman William A.
Published: October 2014

The Pioneers of Underwater Acoustics Medal is presented to an individual irrespective of nationality, age, or society affiliation, who has made an outstanding contribution to the science of underwater acoustics, as evidenced by publication of research in professional journals or by other accomplishments in the field. The award was named in honor of five pioneers in the field: H. J. W. Fay, R. A. Fessenden. H. C. Hayes, G. W. Pierce, and P. Langevin.
Acoustical Society of America Silver Medal in Speech Communication: Sheila E. Blumstein
Authors: Jongman Allard , Sereno Joan , Baum Shari , Lahiri Aditi
Published: October 2014

The Silver Medal is presented to individuals, without age limitation, for contributions to the advancement of science, engineering, or human welfare through the application of acoustic principles, or through research accomplishment in acoustics.
Wallace Clement Sabine Award of the Acoustical Society of America: Ning Xiang
Authors: Summers Jason E. , Blauert Jens
Published: October 2014

The Wallace Clement Sabine Award is presented to an individual of any nationality who has furthered the knowledge of architectural acoustics, as evidenced by contributions to professional journals and periodicals or by other accomplishments in the field of architectural acoustics.
Speech recognition in adverse conditions
Authors: Bradlow Ann
Published: October 2014

Speech recognition is highly sensitive to adverse conditions at all stages of the speech chain, i.e., the sequence of events that transmits a message from the mind/brain of a speaker through the acoustic medium to the mind/brain of a listener. Adverse conditions can originate from source degradations (e.g., disordered or foreign-accented speech), environmental disturbances (e.g., background sounds with or without energetic masking), and/or receiver (i.e., listener) limitations (e.g., impaired or incomplete language models, peripheral deficiencies, or tasks with high cognitive load). (For more on this classification system, see Mattys, Davis, Bradlow, & Scott, 2012, Language and Cognitive Processes, 27). This talk will present a series of studies focused on linguistic aspects of these various possible sources of adverse conditions for speech recognition. In particular, we will demonstrate separate and combined influences of the talker’s language background (a possible source degradation), the presence of a background speech masker in either the same or a different language from that of the target speech (a possible environmental degradation), and the listener’s experience with the language of the target and/or masking speech (a possible receiver limitation). Together, these studies demonstrate strong influences of language and linguistic experience on speech recognition in adverse conditions.
Speech intelligibility and sentence recognition memory in noise
Authors: Smiljanic Rajka
Published: October 2014

Much of daily communication occurs in adverse conditions impacting various levels of speech processing negatively. These adverse conditions may originate in talker- (fast, reduced speech), signal- (noise or degraded target signal), and listener- (impeded access or decoding of the target speech signal) oriented limitations, and may have consequences for perceptual processes, representations, attention, and memory functions (see Mattys et al., 2012 for a review). In this talk, I first discuss a set of experiments that explore the extent to which listener-oriented clear speech and speech produced in response to noise (noise-adapted speech) by children, young adults and older adults contribute to enhanced word recognition in challenging listening conditions. Next, I discuss whether intelligibility-enhancing speaking style modifications impact speech processing beyond word recognition, namely recognition memory for sentences. The results show that effortful speech processing in challenging listening environments can be improved by speaking style adaptations on the part of the talker. In addition to enhanced intelligibility, a substantial improvement in sentence recognition memory can be achieved through speaker adaptations to the environment and to the listener when in adverse conditions. These results have implications for the quality of speech communication in a variety of environments, such as classrooms and hospitals.
Improved speech understanding and amplitude modulation sensitivity in rooms: Wait a second!
Authors: Zahorik Pavel , Anderson Paul W. , Brandewie Eugene , Srinivasan Nirmal K.
Published: October 2014

Sound transmission between source and receiver can be profoundly affected by room acoustics, yet under many circumstances, these acoustical effects have relatively minor perceptual consequences. This may be explained, in part, by listener adaptation to the acoustics of the listening environment. Here, evidence that room adaptation improves speech understanding is summarized. The adaptation is rapid (around 1 s), and observable for a variety of speech materials. It also appears to depend critically on the amplitude modulation characteristic of the signal reaching the ear, and as a result, similar room adaptation effects have been observed for measurements of amplitude modulation sensitivity. A better understanding of room adaptation effects will hopefully contribute to improved methods for speech transmission in rooms for both normally hearing and hearing-impaired listeners. [Work supported by NIDCD.]
The importance of attention, localization, and source separation to speech cognition and recall
Authors: Griesinger David H.
Published: October 2014

Acoustic standards for speech are based on word recognition. But for successful communication sound must be detected, separated from noise and other streams, phones, syllables, and words must be recognized and parsed into sentences, meaning must be found by relating the sentences to previous knowledge, and finally information must be stored in long term memory. All of these tasks require time and working memory. Acoustical conditions that increases the difficulty of any part of the task reduce recall. But attention is possibly the most important factor in successful communication. There is compelling anecdotal evidence that sound profoundly and involuntarily influences attention. Humans detect in fractions of a second whether a sound source is close, independent of its loudness and frequency content. When sound is perceived as close it demands a degree of attention that distant sound does not. The mechanism of detection relies on the phase relationships between harmonics of complex tones in the vocal formant range, properties of sound that also ease word recognition and source separation. We will present the physics of this process and the acoustic properties that enable it. Our goal is to increase attention and recall in venues of all types.
The neural basis of informational and energetic masking effects in the perception and production of speech
Authors: Evans Samuel , McGettigan Carolyn , Agnew Zarinah , Rosen Stuart , Cesar Lima , Boebinger Dana , Ostarek Markus , Chen Sinead H. , Richards Angela , Meekings Sophie , Scott Sophie K.
Published: October 2014

When we have spoken conversations, it is usually in the context of competing sounds within our environment. Speech can be masked by many different kinds of sounds, for example, machinery noise and the speech of others, and these different sounds place differing demands on cognitive resources. In this talk, I will present data from a series of functional magnetic resonance imaging (fMRI) studies in which the informational properties of background sounds have been manipulated to make them more or less similar to speech. I will demonstrate the neural effects associated with speaking over and listening to these sounds, and demonstrate how in perception these effects are modulated by the age of the listener. The results will be interpreted within a framework of auditory processing developed from primate neurophysiology and human functional imaging work (Rauschecker and Scott 2009).
In praise of smooth surfaces: Promoting a balance between specular and diffuse surfaces in performance space design
Authors: Miller Gregory A. , Pfeiffer Scott D.
Published: October 2014

Diffusive surfaces are often presented as a panacea for achieving desirable listening conditions in performance spaces. While diffusive surfaces are a valuable and necessary part of the finish palette in any theater or concert hall, a significant number of specular surfaces are crucial to the success of many such spaces. Case studies will be presented in which excessive use of diffusion has resulted in losses of clarity and loudness, including comparisons to the results following the introduction of specular surfaces, either flat or gently curved. Aural examples will be presented to demonstrate the perceptual differences when specular surfaces are employed as compared to highly diffusive surfaces at key locations in spaces for music and drama.
Scattershot: A look at designing, integrating, and measuring diffusion
Authors: Kanter Shane J. , Strong John , Giegold Carl , Pfeiffer Scott
Published: October 2014

A primary goal of the small-scale performance venue is to provide the audience with supportive, well-timed reflections and to energize the space adequately without overpowering the room volume. The judicious use of sound-diffusive elements in such venues can lend a pleasing sense of body and space while avoiding undesirable reflections that disrupt the listener experience. However, while working with architects to develop a space that is pleasing to both the ear and the eye, it is often necessary to reconcile these needs with each other. Diffusive elements must integrate seamlessly within the space visually as well as architecturally. While developing interior room acoustics for three small spaces for performance/worship, with audience size ranging from 150 to 299, an exploration of diffusive elements was conducted. As each project required a different method and frequency range of diffusion, scale models were constructed and tested under varied conditions, using sometimes unorthodox methods to determine the acoustic effect. These efforts were focused on limiting coloration caused by the “picket fence effect,” reducing harsh reflections without rendering a space excessively sound-absorptive, and maintaining coherent reflections from discrete sections of a prominent wall while leaving other sections diffusive. Methods, experiences, and results will be presented.
Estimating density from passive acoustics: Are we there yet?
Authors: Marques Tiago A. , Harris Danielle , Thomas Len
Published: October 2014

In the last few years, there have been a considerable number of papers describing methods or case studies involving passive acoustic density estimation. While this might be interpreted as evidence that density estimates might now be easily and routinely implemented, the truth is that so far these methods and applications have been essentially proof-of-concept in nature, based in areas and/or species particularly suited for the methods and also often involved assumptions hard to evaluate. We briefly review some of the existing work in this area concentrating on a few aspects we believe are key for the implementation of density estimation from passive acoustics in a broader context. These are (1) the development of fundamental research addressing the problem of sound production rate, fundamental as it allows to convert estimates of density of sounds into density of animals and (2) the development of hardware capable of providing cheap deployable units capable of ranging, allowing straightforward implementations of distance sampling based approaches. The perfect density estimate is out there waiting to happen, but we have not found it yet.
Acoustic capture-recapture methods for animal density estimation
Authors: Borchers David
Published: October 2014

Capture-recapture methods are one of the two most widely-used methods of estimating wildlife density and abundance. They can be used with passive acoustic detectors—in which case acoustic detection on a detector constitutes “capture” and detection on other detectors and/or at other times constitute “recaptures.” Unbiased estimation of animal density from any capture-recapture survey requires that the effective area of the detectors be estimated, and information on detected animals' locations are essential for this. While locations are not observed, acoustic data contain information on location in a variety of guises, including time-difference-of arrival, signal strength, and sometimes directional information. This talk gives an overview of the use of such data with spatially explicit capture-recapture (SECR) methods, including consideration of some of the particular challenges that acoustic data present for SECR methods, ways of dealing with these, and an outline of some unresolved issues.
U.S. Navy application and interest in passive acoustics for estimation of marine mammal population density
Authors: Kumar Anu , Johnson Chip , Rivers Julie , Nissen Jene , Bell Joel
Published: October 2014

Marine species population density estimation from passive acoustic monitoring is an emergent topic of interest to the U.S. Navy. Density estimates are used by the Navy and other Federal partners in effects modeling for environmental compliance documentation. Current traditional methods of marine mammal density estimation via visual line transect surveys require expensive ship time and long days at-sea for an experienced crew to yield limited spatial and temporal coverage. While visual surveys remain an effective means of deriving density estimates, passive acoustic based density estimation methods have the unique ability to improve on visual density estimates for some key species by: (a) expanding spatial and temporal density coverage, (b) providing coverage in areas too remote or difficult for traditional visual surveys, (c) reduce the statistical uncertainty of a given density estimate, and (d) providing estimates for species that are difficult to survey visually (e.g., minke and beaked whales). The U.S. Navy has invested in research for the development, refinement, and scientific validation of passive acoustic methods for cost effective density estimates in the future. The value, importance, and current development in passive acoustic-based density estimation methods for Navy applications will be discussed.
From clicks to counts: Applying line-transect methods to passive acoustic monitoring of sperm whales in the Gulf of Alaska
Authors: Yack Tina M. , Norris Thomas F. , Ferguson Elizabeth , Rone Brenda K. , Zerbini Alexandre N.
Published: October 2014

A visual and acoustic line-transect survey of marine mammals was conducted in the central Gulf of Alaska (GoA) during the summer of 2013. The survey area was divided into four sub-strata to reflect four distinct habitats; “inshore,” “slope,” “offshore,” and “seamount.” Passive acoustic monitoring was conducted using a towed-hydrophone array system. One of the main objectives of the acoustic survey was to obtain an acoustic-based density estimate for sperm whales. A total of 241 acoustic encounters of sperm whales during 6,304 km of effort were obtained compared to 19 visual encounters during 4,155 km of effort. Line-transect analytical methods were used to estimate the abundance of sperm whales. To estimate the detection function, target motion analysis was used to obtain perpendicular distances to individual sperm whales. An acoustic-based density and abundance estimate was obtained for each stratum (N = 78; CV = 0.36 offshore; N = 16; CV = 0.55 seamount; N = 121; and CV = 0.18 slope) and for the entire survey area (N = 215; D = 0.0013; and CV = 0.18). These results will be compared to visual-based estimates. The advantages and disadvantages of acoustic-based density estimates as well as application of these methods to other species (e.g., beaked whales) and areas will be discussed.
Estimating relative abundance of singing humpback whales in Los Cabos, México, using diffuse ambient noise
Authors: Seger Kerri , Thode Aaron M. , López Arzate Diana C. , Urbán Jorge
Published: October 2014

Previous research has speculated that diffuse ambient noise levels can be used to estimate relative cetacean abundance in certain locations when baleen whale vocal activity dominates the soundscape (Au et al., 2000; Mellinger et al., 2009). During the 2013 and 2014 humpback whale breeding seasons off Los Cabos, Mexico, visual point and line transects were conducted alongside two bottom-mounted acoustic deployments. As theorized, preliminary analysis of ambient noise between 100 and 1,000 Hz is dominated by humpback whale song. It also displays a diel cycle similar to that found in the West Indies, Australia, and Hawai’i, whereby peak levels occur near midnight and troughs occur soon after sunrise (Au et al., 2000; McCauley et al., 1996). Depending upon site and year, the median band-integrated levels fluctuated between 7 and 16 dB re 1 uPa when sampled in one hour increments. This presentation uses analytical models of wind-generated noise in an ocean waveguide to analyze potential relationships between singing whale density and diffuse ambient noise levels. It explores whether various diel cycle strengths (peak-to-peak measurements and Fourier analysis) correspond with trends observed from concurrent visual censuses. [Work sponsored by the Ocean Foundation.]
Large-scale static acoustic survey of a low-density population—Estimating the abundance of the Baltic Sea harbor porpoise
Authors: Koblitz Jens C. , Amundin Mats , Carlström Julia , Thomas Len , Carlén Ida , Teilmann Jonas , Tregenza Nick , Wennerberg Daniel , Kyhn Line , Svegaard Signe , Koza Radek , Kosecka Monika , Pawliczka Iwona , Tiberi Ljungqvist Cinthia , Brundiers Katharina , Wright Andrew , Mikkelsen Lonnie , Tougaard Jakob , Loisa Olli , Galatius Anders , Jüssi Ivar , Benke Harald
Published: October 2014

SAMBAH (Static Acoustic Monitoring of the Baltic Sea Harbor Porpoise) is an EU LIFE + -funded project with the primary goal of estimating the abundance and distribution of the critically endangered Baltic Sea harbor porpoise. From May 2011 to April 2013, project members in all EU countries around the Baltic Sea undertook a static acoustic survey using 304 porpoise detectors distributed in a randomly positioned systematic grid in waters 5–80 m deep. In the recorded data, click trains originating from porpoises have been identified automatically using an algorithm developed specifically for Baltic conditions. To determine the click train C-POD detection function, a series of experiments have been carried out, including acoustic tracking of wild free ranging porpoises using hydrophone arrays in an area with moored C-PODs and playbacks of porpoise-like signals at SAMBAH C-PODs during various hydrological conditions. Porpoise abundance has been estimated by counting the number of individuals detected in short time interval windows (snapshots), and then accounting for false positive detections, probability of animals being silent, and probability of detection of non-silent animals within a specified maximum range. We describe the method in detail, and how the auxiliary experiments have enabled us to estimate the required quantities.
Bubbles in tissue: Yes or No?
Authors: Church Charles C.
Published: October 2014

The question of whether bubbles exist in most or all biological tissues rather than being restricted to only a few well-known examples remains a mystery. When Apfel and Holland developed the theoretical background for the mechanical index (MI), they first assumed that such bubbles did exist and further assumed that some of those bubbles were of a size that would undergo inertial cavitation at the lowest possible rarefactional pressure. Comparison of cavitation thresholds determined experimentally in various mammalian tissues in vivo with the results of computational studies seems to provide a definitive answer to that question. No, optimally sized bubbles do not pre-exist in tissue, although very small bubbles, with radii on the order of nm, may be present. However, this answer is inextricably related to the accuracy of the theory used to study the question, in this case a form of the Keller-Miksis equation modified to include the viscoelastic properties of tissue. Previous analysis has focused on elasticity, assuming that viscosity is constant, but is it? Blood is known to be shear-thinning, and some soft tissues appear to be as well. The effect of shear rate on cavitation thresholds and implications for bubble populations in tissue will be discussed.
Standards for characterizing highly nonlinear acoustic output from therapeutic ultrasound devices: Current methods and future challenges
Authors: Szabo Thomas L.
Published: October 2014

One of the major challenges of characterizing the acoustic fields and power from diagnostic and high intensity or high pressure therapeutic devices is addressing the impact of amplitude-dependent nonlinear propagation effects. The destructive capabilities of high intensity therapeutic devices (HITU) make acoustic output measurements with conventional fragile sensors used for diagnostic ultrasound difficult. Different approaches involving more robust measurement devices, scaling and simulation are described in two recent IEC documents, IEC TS 62556 for the specification and measurement of HITU fields and IEC 62555 for the measurement of acoustic power from HITU devices. Existing and proposed applications include even higher pressure levels and use of cavitation effects. Promising hybrid approaches involve a combination of measurement and simulation. In order to meet the challenges of design, verification, and measurement, standards and consensus are needed to couple the measurements to the prediction of acoustic output in realistic tissue models as well as associated effects such as acoustic radiation force and temperature elevation.
Uncertainties in characterization of high-intensity, nonlinear pressure fields for therapeutic applications
Authors: Kreider Wayne , Yuldashev Petr V. , Maxwell Adam D. , Khokhlova Tatiana D. , Tsysar Sergey A. , Bailey Michael R. , Sapozhnikov Oleg A. , Khokhlova Vera A.
Published: October 2014

A fundamental aspect of developing therapeutic ultrasound applications is the need to quantitatively characterize the acoustic fields delivered by transducers. A typical approach is to make direct pressure measurements in water. With very high intensities and potentially shocks, executing this approach is problematic because of the strict requirements imposed on hydrophone bandwidth, robustness, and size. To overcome these issues, a method has been proposed that relies on acoustic holography and simulations of nonlinear propagation based on the 3D Westervelt model. This approach has been applied to several therapy transducers including a multi-element phased array. Uncertainties in the approach can be evaluated for both model boundary conditions determined from linear holography and the nonlinear focusing gain achieved at high power levels. Neglecting hydrophone calibration uncertainties, errors associated with the holography technique remain less than about 10% in practice. To assess the accuracy of nonlinear simulations, results were compared to independent measurements of focal waveforms using a fiber optic probe hydrophone (FOPH). When relative calibration uncertainties between the capsule hydrophone and FOPH are mitigated, simulations and FOPH measurements agree within about 15% for peak pressures at the focus. [Work supported by NIH grants EB016118, EB007643, T32 DK007779, DK43881, and NSBRI through NASA NCC 9-58.]
Technical advances for histotripsy: Strategic ultrasound pulsing methods for precise histotripsy lesion formation
Authors: Lin Kuang-Wei , Hall Timothy L. , Xu Zhen , Cain Charles A.
Published: October 2014

Conventional histotripsy uses ultrasound pulses longer than three cycles wherein the bubble cloud formation relies on the pressure-release scattering of the positive shock fronts from sparsely distributed single cavitation bubbles, making the cavitation event unpredictable and sometimes chaotic. Recently, we have developed three new strategic histotripsy pulsing techniques to further increase the precision of cavitation cloud and lesion formation. (1) Microtripsy: When applying histotripsy pulses shorter than three cycles, the formation of a dense bubble cloud only depends on the applied peak negative pressure (P-) exceeding an intrinsic threshold of the medium. With a P- not significantly higher than this, very precise sub-vocal-volume lesions can be generated. (2) Dual-beam histotripsy: A sub-threshold high-frequency pulse (perhaps from an imaging transducer) is enabled by a sub-threshold low-frequency pump pulse to exceed the intrinsic threshold and produces very precise lesions. (3) Frequency compounding: a near monopolar pulse can be synthesized using a frequency-compounding transducer (an array transducer consisting of elements with various resonant frequencies). By adjusting time delays for individual frequency components and allowing their principal negative peaks to arrive at the focus concurrently, a near monopolar pulse with a dominant negative phase can be generated (no complicating high peak positive shock fronts).
The self-sustained oscillator as an underwater low frequency projector: Progress report
Authors: Acquaviva Andrew A. , Thompson Stephen C.
Published: October 2014

Wind musical instruments are examples of pressure operated self-sustained oscillators that act as acoustic projectors. Recent studies have shown that this type of self-sustained oscillator can also be implemented underwater as a low frequency projector. However, the results of the early feasibility studies were complicated by the existence of cavitation in the high pressure region of the resonator. A redesign has eliminated the cavitation and allows better comparison with analytical calculations.
Design and testing of an underwater acoustic Fresnel zone plate diffractive lens
Authors: Calvo David C. , Thangawng Abel L. , Nicholas Michael , Layman Christopher N.
Published: October 2014

Fresnel zone plate (FZP) lenses offer a means of focusing sound based on diffraction in cases where the thickness of conventional lenses may be impractical. A binary-profile FZP for underwater use featuring a center acoustically opaque disk with alternating transparent and opaque annular regions was fabricated to operate nominally at 200 kHz. The overall diameter of the lens was 13 in. and consisted of 13 opaque annuli. The opaque regions were 3 mm thick and made from silicone rubber with a high concentration of gas voids. These regions were bonded to an acoustically transparent silicone rubber substrate film that was 1 mm thick. The FZP was situated in a frame and tested in a 5 x 4 x 4 cu. ft. ultrasonic tank using a piston source for insonification. The measured focal distance for normal incidence of 12.5 cm agreed with finite-element predictions taking into account the wavefront curvature of the incident field which had to be included given the finite dimensions of tank. The focal gain was measured to be 20 dB. The radius to the first null at the focal plane was approximately 4 mm, which agreed with theoretical resolution predictions. [Work sponsored by the Office of Naval Research.]
A non-conventional acoustic transduction method using fluidic laminar proportional amplifiers
Authors: Scanlon Michael V.
Published: October 2014

Pressure sensing using fluidic laminar proportional amplifiers (LPAs) was developed at Harry Diamond Laboratories in the late 1970s and was applied to acoustic detection and amplification. LPAs use a partially constrained laminar jet of low-pressure air as the sensing medium, which is deflected by the incoming acoustic signal. LPA geometries enable pressure gain by focusing incoming pressure fluctuations at the jet’s nozzle exit, thereby applying leverage to create jet deflection over its short transit toward a splitter. With no input signal, the jet is not deflected and downstream pressures on both sides of the splitter are equal. A differential input signal of magnitude one, referenced to ambient pressure balancing the opposite side of the jet, produces an differential output signal of magnitude ten. This amplified signal can be differentially fed into the inputs on both sides of the next LPA for additional gain. By cascading LPAs together, very small signals can be amplified a large amount. Originally, a DC pressure amplifier, LPAs have exceptional infrasound response, and excellent sensitivity since there is no mass or stiffness associated with a diaphragm, and is matched to the environment. Standard microphones at the output ports can take advantage of increased sensitivity and gain.
Borehole sonic imaging applications
Authors: Market Jennifer
Published: October 2014

The advent of azimuthal logging-while-drilling (LWD) sonic tools has opened up a surfeit of near-real time applications. Azimuthal images of compressional and shear velocities allow for geosteering, fracture identification, stress profiling, production enhancement, and 3D wellbore stability analysis. Combining borehole sonic images with electrical, gamma ray, and density images yields a detailed picture of the near- and far-wellbore nature of the stress field and resultant fracturing. A brief review of the physics of azimuthal sonic logging will be presented, paying particular attention to azimuthal resolution and depth of investigation. Examples of combined interpretations of sonic, density, and electrical images will be shown to illustrate fracture characterization, unconventional reservoir completion planning, and geosteering. Finally, recommendations for the optimized acquisition of borehole sonic images will be discussed.
Numerical simulations of an electromagnetic actuator in a low-frequency range for dipole acoustic wave logging
Authors: Zhou Yinqiu , Xin Penglai , Wang Xiuming
Published: October 2014

In dipole acoustic logging, transducers are required to work in a low frequency range, such as 0.5–5 kHz, to measure shear wave velocities so as to accurately analyze the anisotropy parameters of formations. In this paper, an electromagnetic actuator is designed for more effective low-frequency excitations than conventional piezoelectric bender-bar transducers. A numerical model has been set up to simulate electromagnetic actuators to generate flexural waves. The Finite Element Method (FEM) has been applied to simulating the radiation modes and harmonic responses of the actuator in a fluid, such as air and water. In the frequency range of 0–5 kHz, the first ten vibration modes are simulated and analyzed. The simulation results of 3-D harmonic responses of the sound field, such as the deformation, acoustic sound pressure, and directivity pattern, have been conducted to evaluate the radiation performance. From the simulation results, it is concluded that the second asymmetric mode at 670 Hz could be excited more easily than the others. This oscillated-vibration mode is useful to be applied in a dipole source. The frequency response curve is broad and flat and the electromagnetic actuator is beneficial to generate the wideband signal in a required low frequency range, especially below 1 kHz.
Phase moveout method for extracting flexural mode dispersion and borehole properties
Authors: Assous Said , Eccles David , Elkington Peter
Published: October 2014

Among the dispersive modes encountered in acoustic well logging applications is the flexural mode associated with dipole source excitations whose low frequency asymptote provides the only reliable means of determining shear velocity in slow rock formations. We have developed a phase moveout method for extracting flexural mode dispersion curves from with excellent velocity resolution; the method is entirely data-driven, but in combination with a forward model able to generate theoretical dispersion curves, we are able to address the inverse problem and extract formation and borehole properties in addition to the rock shear velocity. The concept is demonstrated using data from isotropic and anisotropic formations.
Borehole acoustic array processing methods: A review
Authors: Assous Said , Elkington Peter
Published: October 2014

In this talk, we review the different borehole acoustic array methods and compare their effectiveness with simulated and real waveform examples: Starting from the slowness time coherence (STC) method, weighted semblance method (WSS), and many other common dispersive processing approaches including: Prony’s method, maximum entropy (ARMA) methods, and predictive array processing and Matrix pencil technique. We also discuss the Methods include phase minimization or coherency maximization and phase-based approaches.
Classifying and removing monopole mode propagating through drill collar
Authors: Sakiyama Naoki , Dumont Alain , Izuhara Wataru , Yamamoto Hiroaki , Katayama Makito , Fukushima Takeshi
Published: October 2014

Understanding characteristics of the acoustic wave propagating through drill collars is important for formation evaluation with logging-while-drilling (LWD) sonic tools. Knowing the frequency-slowness information of different types of the wave propagating through the collar, we can minimize the unwanted wave propagating through the collar by processing and robustly identify formation compressional and shear arrivals. Extensional modes of the steel drill collar are generally dispersive and range from 180 μs/m to 400 μs/m depending on the frequency band. A fundamental torsional mode of the drill collar is nondispersive, but its slowness is sensitive to the geometry of the drill collar. Depending on the geometry and shear modulus of the material, the slowness of the torsional mode can be slower than 330 μs/m. For identifying slowness of the formation arrivals, those different slownesses of the wave propagating through the collar need to be identified separately from those of the wave propagating through formations. Examining various types of the acoustic wave propagating through a drill collar, we determined that the waves can be properly muted by processing for the semblance of waveforms acquired with LWD sonic tools.
Substrate interaction in ranged photoacoustic spectroscopy of layered samples
Authors: Marcus Logan S. , Holthoff Ellen L. , Pellegrino Paul M.
Published: October 2014

Photoacoustic spectroscopy (PAS) is a useful monitoring technique that is well suited for ranged detection of condensed materials. Ranged PAS has been demonstrated using an interferometer as the sensor. Interferometric measurement of photoacoustic phenomena focuses on the measurement of changes in path length of a probe laser beam. That probe beam measures, without discrimination, the acoustic, thermal, and physical changes to the excited sample and the layer of gas adjacent to the surface of the solid sample. For layered samples, the photoacoustic response of the system is influenced by the physical properties of the substrate as well as the sample under investigation. We will discuss the affect that substrate absorption of the excitation source has on the spectra collected in PAS. We also discuss the role that the vibrational modes of the substrate have in photoacoustic signal generation.
Novel optoacoustic source for arbitrarily shaped acoustic wavefronts
Authors: Chan Weiwei , Yang Yuanxiang , Arora Manish , Ohl Claus-Dieter
Published: October 2014

We present a novel approach to generate arbitrary acoustic wavefronts using the optoacoustic effect on custom designed PDMS substrates. PDMS blocks are casted into the desired shape with a 3D-printed mold and coated with a layer of an optical absorber. Acoustic wavefront corresponding to the geometry of coated surface is generated by exposing this structure to nanosecond laser pulse (Nd:YAG, λ = 532 nm). For a spherical shell design, pressure pulses of amplitude up to 6.1 bar peak to peak and frequency >30 MHz could be generated. By utilizing other geometries, we focus the acoustic waves from different sections of the transmitter onto a single focal point at different time delay, thus permitting generation of double-peak acoustic pulse from a single laser pulse. Further modification of the structure permits designing of multi-foci, multi-peak acoustic pulses from a single optical pulse.
Accuracy of local Kramers–Kronig relations between material damping and dynamic elastic properties
Authors: Pritz Tamas
Published: October 2014

The local Kramers–Kronig (KK) relations are the differential form approximations of the general KK integral equations linking the damping properties (loss modulus or loss factor) and dynamic modulus of elasticity (shear, bulk, etc.) of linear solid viscoelastic materials. The local KK relations are not exact; therefore, their accuracy is known to depend on the rate of frequency variations of material dynamic properties. The accuracy of the local KK relations is investigated in this paper under the assumption that the frequency dependence of the loss modulus obeys a simple power law. It is shown by analytic calculations that the accuracy of prediction of the local KK relations is better than 10% if the exponent in the loss modulus-frequency function is smaller than 0.35. This conclusion supports the result of an earlier numerical study. Some experimental data verifying the theoretical results will be presented. The conclusions drawn in the paper can easily be extended to acoustic wave propagation, namely to the accuracy of local KK relations between attenuation and dispersion of phase velocity.
Caught in the middle: The central problem in diagnosing auditory-processing disorders in adults
Authors: Humes Larry E.
Published: October 2014

It is challenging to establish the existence of higher-level auditory-processing disorders in military veterans with mild Traumatic Brain Injury (TBI). Yet, mild TBI appears to be a highly prevalent disorder among U.S. veterans returning from recent military conflicts in Iraq and Afghanistan. Recent prevalence estimates for mild TBI, for example, among these military veterans have suggest a rate of 7–9% [Carlson, K.F. et al. (2011), “Prevalence, assessment and treatment of mild Traumatic Brain Injury an Posttraumatic Stress Disorder: a systematic review of the evidence,” J. Head Trauma Rehabil., 26, 103–115]. A key factor in diagnosing central components for auditory-processing disorders may lie in the potentially confounding influences of concomitant peripheral auditory and cognitive dysfunction in many veterans with TBI. This situation is strikingly similar to that observed in many older adults. Many older adults, for example, exhibit peripheral hearing loss and typical cognitive-processing deficits often associated with healthy aging. These concomitant problems make the diagnosis of centrally located auditory-processing problems in older adults extremely difficult. After building a case for many similarities between young veterans with mild TBI and older adults with presbycusis, this presentation will focus on several of the lessons learned from research with older adults. [Work supported, in part, by research grant R01 AG008293 from the NIA.]
Lack of a coherent theory limits the diagnosis and prognostic value of the central auditory processing disorder
Authors: Cacace Anthony T. , McFarland Dennis J.
Published: October 2014

Spanning almost 6 decades, CAPD, defined as a modality specific perceptual dysfunction not due to peripheral hearing loss, still remains controversial and requires further development if it is to become a useful clinical entity. Early attempts to quantify the effects of central auditory nervous system lesions based on the use of filtered-speech material, dichotic presentation of digits, and various non-speech tests have generally been abandoned due to lack-of-success. Site-of-lesion approaches have given way to functional considerations whereby attempts to understand underlying processes, improve specificity-of-diagnosis, and delineate modality-specific (auditory) disorders from “non-specific supramodal dysfunctions” like those related to attention and memory have begun to fill the gap. Furthermore, because previous work was generally limited to auditory tasks alone, functional dissociations could not be established and consequently, the need to show the modality-specific nature of the observed deficits has been compromised; further limiting progress in this area. When viewed as a whole, including information from consensus conferences, organizational guidelines, representative studies, etc., what is conspicuously absent is a well-defined theory that permeates all areas of this domain, including the neural substrates of auditory processing. We will discuss the implications of this shortcoming and propose ways to move forward in a meaningful manner.
Cochlear synaptopathy and neurodegeneration in noise and aging: Peripheral contributions to auditory dysfunction with normal thresholds
Authors: Kujawa Sharon G.
Published: October 2014

Declining auditory performance in listeners with normal audiometric thresholds is often attributed to changes in central circuits, based on the widespread view that normal thresholds indicate a lack of cochlear involvement. Recent work in animal models of noise and aging, however, demonstrates that there can be functionally important loss of sensory inner hair cell—afferent fiber communications that go undetected by conventional threshold metrics. We have described a progressive cochlear synaptopathy that leads to proportional neural loss with age, well before loss of hair cells or age-related changes in threshold sensitivity. Similar synaptic and neural losses occur after noise, even when thresholds return to normal. Since the IHC-afferent fiber synapse is the primary conduit for information to flow from the cochlea to the brain, and since each of these cochlear nerve fibers makes synaptic contact with one inner hair cell only, these losses should have significant perceptual consequences, even if thresholds are preserved. The prevalence of such pathology in the human is likely to be high, underscoring the importance of considering peripheral status when studying central contributions to auditory performance declines. [Research supported by R01 DC 008577 and P30 DC 05029.]
Neural correlates of central auditory processing deficits in the auditory midbrain in an animal model of age-related hearing loss
Authors: Walton Joseph P.
Published: October 2014

Age-related hearing loss (ARHL), clinically referred to as presbycusis, affects over 10 million Americans and is considered to be the most common communication disorder in the elderly. Presbycusis can be associated with at least two underlying etiologies, a decline in cochlear function resulting in sensorineural hearing loss, and deficits in auditory processing within the central auditory system. Previous psychoacoustic studies have revealed that aged human listeners display deficits in temporal acuity that worsen with the addition of background noise. Spectral and temporal acuity is essential for following the rapid changes in frequency and intensity that comprise most natural sounds including speech. The perceptual analysis of complex sounds depends to a large extent on the ability of the auditory system to follow and even sharpen neural encoding of rapidly changing acoustic signals, and the inferior colliculus (IC) is a key auditory nucleus involved in temporal and spectral processing. In this talk, I will review neural correlates of temporal and signal-in-noise processing at the level of the auditory midbrain in an animal model of ARHL. Understanding the neural substrate of these perceptual deficits will assist in its diagnosis and rehabilitation, and be crucial to further advances in the design of hearing aids and therapeutic interventions.