bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of three-dimensional time reversal algorithm to locate tinnitus-related hyperactive neurons
Authors: Zhu Na , Wu Sean , Zhang Jinsheng
Published: October 2011

This paper aims at developing 3-D time reversal (TR) algorithm to locate the positions of tinnitus-related neural activities inside the brain auditory pathways, including the auditory cortex (AC), inferior colliculus (IC), and dorsal cochlear nucleus (DCN), which have been implicated in the etiology of tinnitus. Spontaneous neural network signals will be measured by using multichannel electrode arrays that are implanted on the AC, IC, and DCN of adult Sprague Dawley rats and be taken as input to this TR algorithm. To specify the speeds at which neural signals are traveling through the brain auditory pathways, benchmark tests will be conducted, in which electrical stimulations at pre-determined positions in the AC, IC, and DCN will be used, and the corresponding responses be measured. Once this is done, the precise locations of hyperactivity that is responsible for tinnitus perception can be determined by using TR algorithm to scan through the brain auditory pathways. Note that this 3-D time reversal algorithm will allow for tracing neurons into deeper layers of the AC, IC, and DCN, provided that the electrode arrays are implanted in strategically placed in space. Numerical simulations and preliminary experimental results will be presented.
Estimation of seabed parameters in the presence of highly nonlinear internal waves
Authors: Sagers Jason D. , Knobles David P.
Published: October 2011

Nonlinear internal waves (NLIWs) can cause significant scattering of acoustic energy within the modal spectrum. Increased sensitivity to seabed parameters may occur in cases where the primary direction of modal scattering is from lower-angle modes into higher-angle modes, where the mode functions extend deeper into the sediment. In this work, the sensitivity of acoustic propagation to seabed parameters when NLIWs are present is investigated. Comparisons are made between experimental acoustic data from Shallow Water 2006 and modeled acoustic data. The challenge of specifying the temporo-spatial behavior of the water column is addressed so that seabed parameters can be explored.
Altering stage acoustics using time variant electro-acoustic enhancement
Authors: Barbar Steve
Published: October 2011

Time variant electro-acoustic enhancement systems have been successfully installed in a variety of venues and applications since 1990. Many of these systems have included electro-acoustic support for performers on stage, as well as increased direct sound from virtual reflectors, in both indoor and outdoor venues. Examples of these systems and venues are described, including: The Mormon Tabernacle Choir, Vienna Philharmonic Orchestra, and Arnold Schoenberg Choir, Grant Park Symphony, Adelaide Symphony Orchestra, Midland Symphony Orchestra, and Stonebriar Community Church.
Evaluation of the power-law impulse response for liver in the time- and frequency-domains
Authors: Johnson Christopher T. , McGough Robert J.
Published: October 2011

Ultrasound attenuation in biological media often follows a frequency-dependent power-law relationship. Power-law attenuation is accompanied by dispersion in which phase velocity also changes as a function of frequency. The power-law wave equation has exact time- and frequency-domain Green's function solutions that are used in numerical evaluations of the Rayleigh–Sommerfeld diffraction integral. These Green's functions contain stable probability density functions that are evaluated in the time-domain using the STABLE toolbox and in the frequency-domain by evaluating the characteristic function of a stable distribution. The impulse response for a circular piston is evaluated on-axis in the time- and frequency-domain using values for human liver. The results show the accuracy of the time-domain impulse response calculation is dependent upon adequate spatial sampling of the piston face. The frequency-domain impulse response exhibits aliasing caused by wrap around of the heavy tail of the stable distribution. Frequency-domain accuracy is dependent upon the spatial sampling of the piston face and the density of the frequency samples. Numerical evaluations show that the frequency- and time-domain calculations converge to the same result. [This work was supported in part by NIH Grant R01 EB012079.]
Estimation of two-dimensional strain rate based on high frame rate ultrasound imaging method
Authors: Chen Hong , Lu Jian-yu
Published: October 2011

Strain rate (SR) measurement of heart tissue based on ultrasound images provides useful information of tissue hardness for diagnosing heart diseases. However, current SR estimation methods utilizing speckle tracking technique are based on conventional delay and sum (DS) imaging method, which causes skewed heart image resulting in inaccurate SR. To overcome the problem, a method to combine high frame rate (HFR) imaging method with speckle tracking technique was proposed. Using only one or a few transmissions for each image; compared with 91 for DS, new method can get a snapshot of moving targets, avoiding the skewing problem in DS. Two studies, with simulated and experimental echo data, respectively, were performed to verify the method. Both plane wave and limited diffraction beam (LDB) were studied for HFR. Both SR estimations in lateral and axial directions were calculated for the new and conventional ultrasound imaging methods. Results show that the new method has comparable or lower velocity errors than DS and more accurate SR, especially in lateral direction. Moreover, it can measure high velocity for other applications such as blood flow measurement. With the full view of heart image, SR of interest can be localized and then accurately estimated.
A high-dispersion regime of the zero-order symmetric Lamb wave mode for ultrasonic nondestructive evaluation
Authors: Ge Li-Feng
Published: October 2011

The zero-order symmetric Lamb wave mode (S0 mode) has been less studied than antisymmetric one (A0 mode). The S0 mode excited by micromachined electrostatic airborne ultrasonic transducers can be used for nondestructive evaluation of multilayer or composite materials, which deserves special attention. The dispersion curve of the S0 mode is investigated in depth and determined accurately by a three dimensional Plot Method presented previously [Ge, J. Acoust. Soc. Am. 126(4), 2281 (2009); Proc. Meet. Acoust. 8, 065003 (2011)]. It is revealed that as the product of the transverse wave number and thickness increases from a low limit to infinitive the phase velocity of the S0 mode decreases from transverse wave velocity to surface acoustic wave velocity. The low limit determined is 3.46 for Poisson ratio 0.34, and will be 3.31 and 3.05 for 0.28 (steel) and 0.17 (silicon), respectively. Also, it is seen that at a small regime over the limit the S0 mode is highly dispersive. Further, an approximate formula to determine the dispersion relation of the regime is derived analytically for the convenience of practical applications. Since the zero-order mode carries more energy than higher-order modes, the high-dispersion regime is significant particularly for ultrasonic nondestructive evaluation. [Work supported by NSFC (60774053).]
Micromachined ultrasonic transducers and nonclassical nonlinear effects due to domains
Authors: Ostrovskii Igor , Nadtochiy Andriy
Published: October 2011

Two-dimensional ultrasonic transducers and delay lines fabricated on micromachined LiTaO3 and LiNbO3 plates are demonstrated. The 0.5-mm-thick commercial wafers are inversely poled by applying an external electric field to get periodic and aperiodic multidomain structures. The metal electrodes are deposited on the structures to excite ultrasonic vibrations by applying radio frequency voltage. The domain lengths are in a broad range from 16 μm to 1 mm with corresponding frequencies from 347 to 3 MHz. The finite element method is used for computer simulation of the micromachined transducers. Experimental results are in agreement with theoretical calculations. All transducers have a so called domain resonance and operate at frequencies near this resonance. The highest vibration amplitude is usually observed when acoustic wavelength is two times greater than a single domain length. The multidomain structures have their own nonclassical nonlinear properties, which may be explained by domain kinetics and their collective behavior. For instance, an efficiency of transduction may depend on such physical effects like domain reverberations and so called stop-bands in an acoustic superlattice, which in turn are specific functions of frequency and other conditions of excitation. Possible applications of the piezoelectric micromachined transducers and vibrators are discussed. [This work is made possible in part due to the research grants “Nonlinear vibrations of piezoelectric resonators,” UM, 2011; “Multidomain plate acoustic wave devices,” UM, 2007.]
The performance enhancement of the hydrophone based on the piezoelectric gate of field effect transistor for low frequency application
Authors: Sung Min , Shin Kumjae , Moon Wonkyu
Published: October 2011

A hydrophone based on the transduction using the electric field of piezoelectric ceramic directly applied on the gate of field effect transistor was proposed, and the feasibility was shown in the year of 2010. Although the feasibility was proved with proper working condition, the fabricated device had some problems on the stability, noise, and sensitivity. The electric field generated from the piezoelectric ceramic in thickness mode, which receives the acoustic pressure from the pressure amplifying head mass structure, modulates the channel current of field effect transistor. The parametric analysis for the transduction was done for the performance enhancement. To realize stable and highly sensitive modulation, the field effect transistor was designed and fabricated with improved gate insulation layer. The passivation for the field effect transistor was also performed to protect the device from external factors and reduce the noise. The sensitivity evaluation setup using the free field calibration method was modified for more accurate measurement. The evaluation results for the improved device are to be presented. [Research supported by MRCnd.]
Teaching architectural acoustics to architecture, architectural engineering, and music students
Authors: Coffeen Robert C.
Published: October 2011

A rewarding career in architectural acoustics has provided the opportunity to teach as a faculty member of the School of Architecture, Design and Planning at the University of Kansas. This presentation will discuss methods and techniques for teaching the basics of architectural acoustics to architecture students so that they might apply these basics to their building designs, for teaching acoustic basics to music students so that they will appreciate and properly use venues for music performance and rehearsal, and for teaching architecture and architectural engineering students interested in building acoustics and who desire to have a career in professional acoustical consulting. These methods and techniques are built on current acoustic knowledge, measurements, and analysis-measurement computer software; on 35 yr of acoustical consulting experience; on opportunities for assisting with architecture studios, for teaching established courses and portions of courses, and for creating new courses with such opportunities provided by the architecture and the architectural engineering faculty and administration; by the Acoustical Society of America with teaching opportunities such as provided by the annual student design competitions; and by many excellent architecture and architectural engineering students. Specific methods, techniques, presentations, course syllabi, etc., will be discussed.
Hot topics in noise: Wind turbines
Authors: Kaliski Kenneth
Published: October 2011

Since 2000, the installed capacity of wind energy in the U.S. increased seventeen-fold, with the greatest increases in recent years. Today, we commonly find terrestrial wind farms with individual towers of 80–100 m and rotor diameters up to 112 m. The number of wind farms is projected to increase, as many states are adopting renewable energy portfolio standards in an effort to help combat climate change. As wind farms grow, there are inevitably more potential conflicts related to the impacts of the noise generated by the turbines. Noise has taken center stage in both proceedings for proposed wind farms and complaints from some operating wind farms. This talk will review the major issues regarding wind turbine noise, including sound emissions, sound propagation and modeling, sound monitoring, human perception, and regulation. Areas of controversy will be explored, including infrasound and low frequency sound, amplitude modulation, and health impacts.
Standards 101
Authors: Schomer Paul
Published: October 2011

The Acoustical Society of America (ASA) was founded in 1929 and the standards program of the Acoustical Society began in 1930. It followed the establishment of meetings and the journal. Currently, only meetings attract greater participation than does the standards program. Although standards have been an integral part of the ASA for 81 yr, it still remains a mystery to many members. This paper introduces the special session on standards and describes the basic organization and operation of the standards program. It is followed by case studies highlighting the standards process and the reasons organizations of different types and sizes find it worthwhile to participate. While this session primarily has a U.S. perspective, it also includes a paper presenting a non-U.S. perspective.
Tower of Babel, or why bother about international standards?
Authors: Axelsson Osten
Published: October 2011

While a vast nation like the USA has the capacity to be self-sufficient, many countries lack this privilege. Take Sweden as an example, a small country in northern Europe with a population of 9 million. Swedes are proud to be international. And they should, because how could a nation, which since the days of the Vikings has depended on international trade, sustain itself without a global economy. International standards support the development within this global economy, just like English as business language facilitates global collaboration. Imagine humanity without these common frames of reference.
Investigation of the relationship between the vibration patterns of the skull and bone-conducted sound
Authors: Wismer Margaret , O'Brien William
Published: October 2011

Analytic and numerical models are used to evaluate acoustic energy converted into bone conducted sound that reaches the middle and inner ear. Sound impinging upon the skull, from an outside source, is channeled into surface waves on the outside of the skull. These waves have components in both the solid bone and the background medium of air, travel at much slower speeds than longitudinal sound speed for bone and have wavelengths smaller than those of an acoustic signal existing solely in bone or in the cranial cavity. Frequencies, at which an integer number plus one half of surface wave wavelengths fit around the circumference of the sphere, cause resonant vibrations. The added one half is due to phase matching surface waves at the poles. The relatively slow sound and short wavelengths mean resonance frequencies for the skull are lower than if the acoustic energy were confined to standing waves within the cranial cavity wherein wavelengths are longer. At acoustic frequencies skull vibrations are analogous to lowest order flexural modes of a fluid-loaded elastic sphere. Numerical models suggest bone's conducted sounds are confined to the skull surface with wave speeds much lower than speed of sound for boney or soft tissue.
A simplified axi-symmetric finite element model of the human outer ear to determine the earplug induced auditory occlusion effect
Authors: Brummund Martin K. , Sgard Franck , Petit Yvan , Laville Frédéric
Published: October 2011

Earplugs are a frequently used short-term solution for hearing conservation in the workplace environment. Due to limited auditory comfort, however, workers often only wear them for short periods of time and become prone to hearing loss. An important source of discomfort is the auditory occlusion effect, which expresses itself through the distortion of the wearer's voice and the amplification of physiological noises upon earplug insertion. Simplified numerical modeling can help to better assess and design earplugs, because it requires few system resources and is simpler in terms of numerical and experimental implementation than an equivalent complex model. This work describes a novel coupled linear elasto-acoustic two dimensional finite element (FE) model of the human outer ear. The model comprises the auditory canal as well as the bony, cartilaginous, and skin tissues whose material parameters were approximated using literature findings. The outlined model can compute the transfer functions between the sound pressure levels at the eardrum and a structure-borne excitation for both an unoccluded ear and an ear occluded by a molded earplug. Simulated occlusion effects are examined as a function of excitation, earplug, and insertion depth. Predicted model results are compared to literature findings and to findings obtained from an equivalent three dimensional FE-model.
Integrating speech enhancement with subband active noise control to improve communication in hearing protectors
Authors: Bernstein Eric R. , Brammer Anthony J. , Yu Gongqiang , Cherniack Martin G. , Peterson Donald R.
Published: October 2011

Many workers refuse to wear hearing protection devices (HPDs) because they would rather accept the health risks than sacrifice the ability to communicate with coworkers. Integrating active noise reduction (ANR) techniques with speech enhancement algorithms could solve these limitations of modern electronic HPDs. An adaptive delay feedforward subband structure has been implemented by forming parallel signal filtering and filter update paths for each frequency band. Subband ANR provides additional attenuation of environmental noise beyond that of passive HPDs within the lower frequencies associated with speech communication. The subband structure can also provide valuable information regarding the spectral content of the environmental noise that can be exploited to determine where additional power is needed in a communication channel to improve intelligibility. The system, initially developed in simulation, maintains a specified signal-to-noise ratio in each subband while simultaneously limiting the power added by the communication channel to below that associated with hearing damage. Speech Transmission Index models have been used to validate the improvements in speech intelligibility over typical passive and ANR communication headset designs. Preliminary results for a circumaural HPD constructed to implement the concept will be presented for comparison with the simulation. [Work supported by NIOSH (R01 OH008669).]
Speech rhythm analysis with empirical mode decomposition
Authors: Tilsen Sam
Published: October 2011

This paper presents a new approach to characterizing speech rhythm, based upon empirical mode decomposition (EMD) [Huang etal., Proc. R. Soc. London Ser. A 454, 903–995 (1998)]. Intrinsic mode functions (IMFs) are obtained from EMD of a vocalic energy envelope of speech, which is a smoothly varying signal, representing primary vocalic resonance energy. EMD uses an iterative sifting process to decompose the signal into IMFs with zero mean and zero-crossings between extrema. Investigations of IMFs revealed that the last two IMFs appear to capture foot- and syllable-timescale oscillations in the envelope, respectively. EMD was applied to a seven-language corpus of speech previously used to compare languages using interval-based rhythm metrics [Ramus etal., Cognition 73, 265–292 (1999)]. The ratio of signal power in the foot- and syllable-associated IMFs was used as metric of the relative influence of foot-based timing on speech. The performance of the IMF power ratio metric in distinguishing languages is comparable to analyses based on interval metrics. The method is argued to have the potential for broad applicability in speech research.
Comparing envelope- and interval-based rhythm metrics
Authors: Arvaniti Amalia , Tilsen Sam
Published: October 2011

Numerous metrics have been developed in the attempt to characterize cross-linguistic differences in speech rhythm, particularly with regard to the rhythm class hypothesis, which holds that languages differ in whether they privilege regularity in timing of stress, syllables, or moras. This paper tests for consistency in the performance of different types of rhythm metrics, using speech corpora of English, German, Greek, Italian, Korean, and Spanish obtained from eight speakers of each language with three elicitation methods: read sentences, read running text, and spontaneous speech. Rhythm metrics tested were: interval-based metrics derived from durations of consonantal and vocalic intervals, low-frequency spectral analysis of the vocalic energy envelope, and a recently developed metric based upon the power ratio of foot and syllable intrinsic mode functions obtained from empirical mode decomposition of the vocalic envelope. For all languages, the metrics indicate that spontaneous speech exhibits more stress-timing like characteristics than read speech, having higher interval variability and more dominant stress-timescale periodicity in the envelope. Cross-linguistic differences emerged in some cases, but these were not entirely consistent across metrics and were affected by the elicitation method. Overall the data suggest that the elicitation effects (i.e., read versus spontaneous speech) are larger than differences between languages.
Speech cycling in Korean
Authors: Chung Younah
Published: October 2011

This paper reports the results of a cycling experiment in Korean, a paradigm in which speakers produce short phrases in time with a metronome. It was hypothesized that in Korean the onsets of accentual phrases would act as beats in this task, playing the same part as stress plays in English; therefore, the accentual phase onsets would remain in the same phase within a cycle independently of their composition. Speakers read Korean sentences with three accentual phrases that had the same number of syllables or differed so one of the accentual phrases had twice as many syllables as the others; the composition of the syllables also varied between CV and CVC. The results so far suggest that speakers keep the accentual phrases in phase although the variation of syllable count and composition also affected phasing. This provides evidence that cycling is a viable task in Korean and supports our hypothesis about the role of the accentual phrase in Korean rhythm. Finally, the relative importance of the syllable cycle supports a view of rhythm that does not rest on the timing of one prosodic constituent, such as the accentual phrase, but on the relative salience of different levels of prosodic structure.
Tone-based macro-rhythm from the perspective of prosodic typology
Authors: Jun Sun-Ah
Published: October 2011

In the autosegmental-metrical model of intonational phonology [Pierrehumbert, 1980, Ladd, 1996/2008], prosody is defined in terms of the prosodic structure of an utterance and the prominence relations within the structure. Jun (2005) proposed a model of prosodic typology based on the types of prominence-marking and rhythmic/prosodic units. Languages were categorized as Head-prominence when the head of a prosodic unit such as stress is marked prominent (e.g., English, Spanish, Greek), or Edge-prominence when the edge of a prosodic unit such as an accentual phrase (AP) is marked prominent (e.g., Korean), or Head/Edge-prominence when both the head and the edge are marked prominent (e.g., French, Bengali). The rhythmic/prosodic units covered both micro-rhythm (regularity due to the traditional rhythm category, e.g., stress-timed) and macro-rhythm (regularity due to a tonally defined prosodic unit, e.g., AP). Macro-rhythm was proposed to describe the rhythmic nature of a language where stress is not easily perceptible. In this talk, I will show that macro-rhythm is also crucial in describing sub-groups of Head-prominence languages as well as capturing the relationship between the complexity of tonal category and the types of prominence-marking across languages. Combining the prominence types and the f0-based macro-rhythm provides a better way to establish prosodic typology.
Who is an Acoustician?
Authors: Adams Wendy K.
Published: October 2011

The “traveling road show” originally put together by ASAs own Uwe Hansen includes a range of hands-on demonstrations of physical phenomena such as standing waves & resonance, energy carried by sound, and spectrum analysis just to name a few. This show is presented to Girl Scouts with the goal of exciting young ladies about science and letting them interact with female scientists. To further this goal, I propose creating a station that describes careers of acousticians in the various technical areas to educate the young ladies about what different acousticians do in their day to day activities. Career profiles that were previously created for the exploresound.org website will be used along with information presented in a fun, straightforward, graphical, easy to read poster presentation.
Do you hear what I hear?
Authors: Neilsen Tracianne B.
Published: October 2011

Have you ever wondered if the person next to you hears the same thing you hear? It depends. The response of our ears varies significantly with age because a person's cumulative exposure to noise lessens their ears' ability to respond to sounds. This common form of hearing loss is called presbycusis and is characterized by a significant degradation in the high frequency content of the perceived sound. A series of auditory demonstrations distributed by the Acoustical Testing Center at NASA Glenn Research Center lets you hear what a person with progressively worse presbycusis hears.
Progress in soundscape research requires a common agenda
Authors: Axelsson Osten
Published: October 2011

It is commonly believed that progress and success in any field requires competition. This is probably true, but this belief implies that all competitors have a common view on the objectives. There would not be much competition if all parties ran off in opposite directions, striving to achieve different goals. Nor would it lead to much progress. The present session calls for networking and international collaboration in soundscape research. For such collaboration to be successful, it is critical to agree on a common agenda; a mission; an objective. Recent development in soundscape research makes evident that the objective must be practical and applicable. Our minds must be set to implementing soundscape research in practice to avoid exhausting academic debates, which tend to be ends in themselves and do not contribute to progress. Two excellent, recent examples of international collaboration in soundscape research, contributing to progress, are ISO/TC 43/SC 1/WG 54 and the European COST Action TD0804 “Soundscape of European Cities and Landscapes.” Both illustrate the need for international and interdisciplinary collaboration among acousticians, architects, and urban planners to accelerate progress in soundscape research. The present paper presents possible topics for a common agenda in soundscape research.
Impacts on soundscape appreciation by focussing on sources
Authors: Fiebig Andre
Published: October 2011

Based on COST, the European Cooperation in Science and Technology as an instrument supporting cooperation among scientists and researchers across Europe, collaborations among soundscape researchers was and is still encouraged (COST action TD 0804). In this context, researchers from 18 COST countries and 7 partners outside Europe come together and work on terminology, collection and documentation of soundscapes, harmonization of methodologies and indicators, and design of soundscapes. One scientific issue deals with sound source constellations in soundscapes and evoked attention-attracting processes. Humans can easily focus on a certain source suppressing the noise of other sources. This process obviously influences the general appreciation of the whole soundscape. In different tests this phenomenon was investigated and its potential analyzed with respect to soundscape design. The process of international and interdisciplinary cooperation within the COST framework will be shortly described and benefits and limitations discussed. Moreover, different case studies will be presented to show the effect of source attention and its impact on soundscape evaluation.
Application of soundscape method for a worship space
Authors: Park Sang Bum
Published: October 2011

Soundscape methods have been used to investigate the sound quality of natural and urban environments and the effects of sonic events on people. Soundscape methods can also be used to study the dynamic listening, speaking, and musical acoustical environment of a worship space. Observations of services in three worship spaces led to identification of a taxonomy of sounds that occur in the rooms as well as the multiple participants involved in producing the sounds and listening to them, i.e., the acoustic community. Five groups including ministers, the choir, music director, the congregation, and sound engineers each with their own physical location in the room, communication paths, and values were identified. Sound sources and receivers for physical acoustical measurements and questionnaires were located for each of the groups. Sound systems were used in each space for various reasons. Analysis of physical acoustical measurements and survey results revealed that different groups had different experiences in the worship spaces when the sound system was used and when it was not used.
Marine mammal vocalizations and shipping patterns off the California coast near Sur Ridge
Authors: Joseph John E. , Stimpert Alison K. , Margolina Tetyana , Miller Christopher W.
Published: October 2011

Studying the effects of anthropogenic noise on marine life is the focus of many ongoing research efforts, and regional studies can provide useful insight into the broader issues. Waters off the central California coast are well known for the rich occurrence of a variety of marine mammal species. The region also contains important ship routes used by vessels transiting between major US west coast ports. Here, we examine the relationship between marine mammal vocalizations collected near Sur Ridge and local shipping patterns determined from automatic identification system (AIS) reports broadcast by ships passing through the region. Passive acoustic recordings of vocalizations were acquired with a moored high-frequency acoustic recording package (HARP) over the frequency bandwidth 10 Hz–100 kHz. Number of vessels within several different radii from the HARP mooring is correlated with presence/absence data of several baleen whale, beaked whale, and dolphin species over 5-min intervals between January 2009 and November 2010. We also examine whether diel patterns of marine mammal distribution are influenced by diel patterns in ship traffic. These data will be useful for establishing mammal-vessel interaction rates in the Monterey Bay National Marine Sanctuary. [Research supported by US Navy CNO(N45)].
Nighttime foraging by deep diving echolocating odtonocetes in the Hawaiian Islands
Authors: Au Whitlow W. L. , Giorli Giacomo , Richlen Michael , Lammers Marc O.
Published: October 2011

Ecological acoustic recorders (EARs) were deployed in deep waters at five locations around the island of Kauai and one in waters off Ni'ihau in the main Hawaiian island chain. The EARs were moored to the bottom at depths between 400 and 800 m. The data acquisition sampling rate was 80 kHz and acoustic signals were recorded for 30 s every 5 min to conserve battery power and disk space. The acoustic data were analyzed using a suite of software including the M3R (marine mammal monitoring on navy ranges) algorithm, an energy-ratio-mapping algorithm developed at Oregon State University, Triton software developed at Scripps Institute of Oceanography, and custom Matlab programs. A variety of deep diving odontocetes, including pilot whales, Risso's dolphins, sperm whales, spinner and pan-tropical spotted dolphins, and beaked whales were detected at all sites. Foraging activity typically began to increase after dusk, peaked in the middle of the night, and began to decrease toward dawn. Between 75 and 87% of biosonar clicks were detected at night. At present, it is not clear why some of the known deep diving species, such as sperm whales and beaked whales, concentrate their foraging efforts at night.
Long term remote monitoring of cetacean calls using a solar powered autonomous detector
Authors: Gillespie Douglas , Maginnis Andrew , Hastie Gordon
Published: October 2011

The use of autonomous underwater recording devices is now well established as a method for long term population monitoring. However, the life time of autonomous recorders is still restricted by battery lifetimes and, particularly when monitoring at high frequencies, by available storage space. We present a system for long term monitoring of cetacean populations using a solar powered system in which real time detection algorithms for multiple species can run concurrently on an embedded processing platform. Power consumption is typically below 3 W, with sample rates of up to 500 kHz; the system is therefore suitable for the detection of all known cetacean calls. Data volumes of detected calls are typically below 1 MB a day, meaning that data can be transmitted ashore in near real time using cell or satellite phone networks. Furthermore, communications are bi-directional allowing sampling and detection parameters to be updated remotely. The combination of solar power, real time processing, and data transmission denotes that deployment lifetimes are limited only by the mechanics of the mooring and the need to remove bio-fouling from hydrophones.
Low frequency therapeutic ultrasound causes vasodilation and enhanced tissue perfusion
Authors: Siegel Robert J.
Published: October 2011

It has been found that ultrasound has a unique effect on arterial and venous dilation as well as tissue perfusion. Our group found that low frequency ultrasound (20 kHz, 0.1 w/cm2) results in coronary arterial and coronary venous dilation in dogs. The magnitude of vasodilation is similar to that seen with nitroglycerine (NTG) administration but unlike NTG, USD does not lower blood pressure. Our human studies show that USD induces brachial arterial dilation after 1 min with the vasodilatory effect lasting 20 min. In animals we ligated coronary arteries, stopping epicardial coronary flow, resulting in a drop in myocardial tissue perfusion to 70% of normal; myocardial tissue pH fell from 7.43 to 7.05. After 60 min of USD, tissue perfusion improved by 20% and pH normalized in spite of persistent coronary artery occlusion. The enhanced perfusion effect of ultrasound was eliminated if an inhibitor of nitric oxide synthase was given prior to ultrasound exposure. Conclusions: low frequency ultrasound causes vasodilation and improves tissue perfusion. These effects appear to be mediated at least in part by the USD enhancing tissue release of nitric oxide.
Assessing thrombolytic efficacy in vitro: Clot mass loss versus fibrinogen protein fragment concentration
Authors: Perrin Stephen R. , Pyne-Geithman Gail J. , Ivancevich Nikolas M. , Beiler Shauna L. , Wagner Kenneth R. , Holland Christy K.
Published: October 2011

Ultrasound (US) acts synergistically with recombinant tissue plasminogen activator (rt-PA) to accelerate thrombolysis. A correlation between clot mass loss and production of the fibrin degradation product D-dimer was investigated using an in vitro clot thrombolysis model. Fully retracted clots formed from 1.5-ml human whole blood were suspended in plasma at 37°C and treated with rt-PA, or rt-PA, Definity®, and pulsed 120-kHz US for 30 min. Clots in plasma alone served as controls. Thrombolytic efficacy was assessed as percent clot mass loss. Samples from plasma surrounding the clot and from macerated clots were analyzed for D-dimer using an enzyme linked immunosorbent serologic assay. A statistically significant enhancement in clot mass loss was observed for clots exposed to rt-PA, Definity®, and US compared to rt-PA alone. Clots treated with rt-PA exhibited a higher concentration of D-dimer both in the clots and plasma. However, clots treated with rt-PA, Definity®, and US did not exhibit an enhanced level of D-dimer. In future studies, we plan to elucidate the role of erythrocyte liberation in US-enhanced clot mass loss. [This work was supported by NIH RO1 NS047603.]
Enhanced viral activity in tumors using focused ultrasound and microbubbles—A long term study
Authors: Choi James J. , Carlisle Robert C. , Coussios Constantin C.
Published: October 2011

Oncolytic viruses target and kill cancer cells and self-amplify through replication. However, viral therapy in vivo is limited by insufficient systemic delivery. Here, focused ultrasound (FUS) was used in conjunction with microbubbles to produce cavitation and enhance tumor viral delivery. Human breast cancer cells (ZR75.1) were injected subcutaneously in mice (n = 8), which grew to a tumor volume of at least 30 mm3. The tumors were then exposed to FUS (frequency: 0.5 MHz, pulse duration: 50 000 cycles, pulse repetition frequency: 0.5 Hz) for 4 min following injection of 100 μl of SonoVue microbubbles (SVM) with polymer-coated adenovirus encoding luciferase (pc-Ad-Luc). Experiments were repeated for three controls: pc-Ad-luc with neither FUS nor SVMs, FUS and SVM without pc-Ad-Luc, and buffer alone. Acoustic emissions were recorded with a passive detector, which validated the presence of inertial cavitation and ensured good SVM reperfusion kinetics. Tumor viral expression was then imaged using IVIS following luciferin injection. At 1, 2, 3, and 7 days post-injection, 3, 20.3, 30.2, and 22.9-fold increases in photons/s/cm2 were observed when pc-Ad-Luc was used with FUS and SVM compared to pc-Ad-Luc alone. In conclusion, FUS and SVM enhanced oncolytic virus delivery resulting in amplified viral expression over time.
Dynamical-systems measures of ultrasound contrast agent proximity to target walls
Authors: Dzaharudin Fatimah , Suslov Sergey A. , Ooi Andrew , Manasseh Richard
Published: October 2011

Targeted ultrasound contrast agents are microbubbles that strongly scatter ultrasound, providing contrast on a scan, and have also been coated in molecules that adhere to target pathologies. The ultimate aim is to identify diseased tissue in clinical ultrasound practice. One issue is to discriminate in real time between microbubbles that have adhered to their target pathologies on blood-vessel walls, from those that are freely flowing in the bloodstream. It is known that linear theory predicts a shift in resonant frequency owing to the presence of a wall. Weakly nonlinear theoretical results are presented on alterations to the dynamical-systems behavior of one or more microbubbles on and near to walls. In particular, the bifurcation diagram is altered as microbubbles approach a wall. Near a wall, period-doubling and period-quadrupling bifurcations and transitions to broadband chaos occur at altered values of the incident pressure amplitude. Alterations in the bifurcation diagram increase as multiple bubbles are held fixed close to each other and to the wall. This suggests that filtering of the returning echoes around selected solution branches could provide a further real-time indicator of locations where targeted ultrasound contrast agents have adhered.
Spatio-temporal mapping and characterization of acoustic cavitation seeded by microbubbles and solid microparticles during focused ultrasound exposure
Authors: Choi James J. , Coussios Constantin C.
Published: October 2011

Cavitation nuclei are often used to seed and promote acoustic cavitation in therapeutic applications. However, the effects of fluid velocity and ultrasound exposure parameters peak rarefactional pressure (Pr), pulse duration (PD), and pulse repetition frequency (PRF) on the spatial distribution, type, magnitude, and number of acoustic cavitation events for each nuclei remains poorly understood. In this study, a 1.6-mm diameter tunnel phantom (3% agar) was perfused (fluid velocity: 10–40 mm/s) with either microbubbles (SonoVue) or hydrophobic solid microparticles (TALC) and exposed to 74 different acoustic parameter combinations (frequency: 0.5 MHz, Pr: 150–1500 kPa, PD: 1–100,000 cycles, PRF: 1–50 Hz, number of pulses: 10–250). Spatial mapping of passively acquired acoustic cavitation emissions was performed with a 64-element array coaxial to the focused ultrasound transducer. At pressures above the cavitation threshold, cavitation activity generated from microbubbles was significantly reduced and spatially biased upstream after the first pulse at high PRFs relative to the fluid velocity. On the other hand, solid microparticles had no spatial bias and no significant reduction in the energy of acoustic emissions after the first pulse. Whereas microbubbles may be destroyed, and therefore, cease to act as cavitation nuclei, solid microparticles do not suffer from depletion of energy with high PRFs.
In vitro acoustic characterization of a novel poly-lactic acid polymer shelled contrast agents
Authors: Paul Shirshendu , Russakow Daniel , Rodger Tyler , Sarkar Kausik , Wheatley Margaret
Published: October 2011

Micron sized encapsulated gas bubbles have been extensively studied as contrast enhancing agents for ultrasound imaging. This study will report on in vitro acoustic characterization of a novel poly-lactic acid (PLA) shelled contrast agent. PLA is a bio-degradable polymer approved by the FDA to be used in drug delivery applications. Thus, PLA shelled contrast bubbles have the potential of being developed as the next generation contrast agents. Both attenuation and scattering measurements will be reported. Attenuation measurements are obtained using three different transducers (central frequencies 2.25, 3.5, and 5 MHz). Pressure dependent scattered response is obtained for two different excitation frequencies of 2.25 and 3.5 MHz. Results indicate excellent scattering properties of the PLA shelled bubbles. The strongly non-linear nature of scattered response makes PLA bubbles a potential choice for harmonic and sub-harmonic contrast imaging applications.
Role of effective surface tension on the frequency dependent subharmonic threshold for contrast microbubbles
Authors: Katiyar Amit , Sarkar Kausik
Published: October 2011

We numerically investigate the predictions from several contrast microbubble models to determine the excitation threshold for subharmonic generation. In contrast to the classical perturbative result, the minimum threshold for subharmonic generation is not always obtained near twice the resonance frequency; instead it can occur over a range of frequency from resonance to twice the resonance frequency. The quantitative variation of the threshold with frequency depends on the model, bubble radius, and encapsulation properties. All models are transformed into a common interfacial rheological form, where encapsulation is represented by two radius dependent surface properties—effective surface tension and surface dilatational viscosity. Variation of the effective surface tension with radius, specifically having an upper limit (resulting from strain softening or rupture of the encapsulation during expansion), plays a critical role. It destroys a sharp minimum at twice the resonance frequency. Without the upper limit on effective interfacial tension, the threshold is extremely large especially near the resonance frequency.
Energy harvesting of tonal sound excited by heat addition and vortex shedding
Authors: Jung Sungmin , Hernandez Rafael , Matveev Konstantin I.
Published: October 2011

Tonal sound may appear inside resonating duct systems due to heat addition or vortex shedding in the presence of mean flow. Amplitudes of this sound can reach significant levels. The sound power can be captured and converted to electricity using electroacoustic transducers. Two pipe setups were constructed to demonstrate energy harvesting of tonal sound using piezoelements. In the first system, the sound was excited by vortex shedding and impingement on baffles in the presence of mean flow. The second system represented closed and open types of a standing-wave thermoacoustic engine. Electric power in excess of 0.5 mW was captured and released on passive electric loads from the tonal sound. This power level is sufficient for some low-power sensors. Further system optimization can significantly increase the amount of harvested energy. [Work supported by the NSF Grant 0853171.]
Electromechanical transduction system design for optimal energy harvesting from ocean waves
Authors: Thiam Amadou G. , Pierce Allan D.
Published: October 2011

While details of the currently most highly publicized devices for conversion of ocean wave energy to electrical energy are generally not disclosed in the open literature, the authors believe that, for devices not on the coastline, the common transduction mechanism involves electromagnetic induction with conducting wires moving relative to permanent magnets. A general discussion is given of how such a mechanism can be used in this application. The overall analysis of the mechanical system with lumped or distributed masses and elastic elements driven by buoyancy forces associated with incident ocean waves is facilitated, if the transduction system is modeled as linear mechanical dashpots, and the procedures for deriving effective dashpot constants are described. The mechanical analysis suggests that, for waves in a general frequency range, there is an optimal choice for the parameters of the mechanical system, so that the maximum electrical power can be harvested. The optimal energy extracted per wave cycle is invariably much less than the total mechanical energy of the oscillating components of the system. A distinction is made between freely floating systems and systems anchored to the ocean bottom and between systems which are driven near a resonant frequency and those driven substantially below resonance.
Design of a wideband multimode tonpilz transducer with a nonuniform piezoelectric layer stack
Authors: Roh Yongrae , Chhith Saosometh
Published: October 2011

It has been well-known that a multimode transducer could provide a wider frequency bandwidth than a single mode one, and conventionally a multimode transducer can be achieved by designing the geometry of its head mass, increasing the head mass radius and reducing the head mass thickness. However, a very large head mass can cause some drawbacks to transducer performance when used in an array, i.e., low source level and big crosstalk with neighboring transducer elements. In this work, a new and very simple design method has been developed to widen the bandwidth of a Tonpilz transducer, which is replacing the uniform PZT layer stack by a nonuniform one. A piezoelectric stack composed of nonuniform PZT layers can generate higher mechanical energy than that composed of uniform layers for the same input electrical energy, which means a higher coupling coefficient thus a wider bandwidth. The effects of the nonuniformity of PZT layer thicknesses on a multimode Tonpilz transducer performance were investigated through finite element analyses. Then, the functional forms of the performance were derived in relation to the nonuniform PZT thicknesses and were inserted into a genetic algorithm to achieve the widest possible bandwidth of the Tonpilz transducer.