bluuebunny/crossref_metadata_2025 huggingface dataset:
Tracking of small vessels with passive acoustic sensors
Authors: Ou Helen H. , Sherpa Pasang , Zurk Lisa M.
Published: October 2011

This paper introduces a small boat vessel tracking method in marine environment using autonomous, low-complexity acoustic sensors. A cross-correlation of time series between sensors generates a coarse localization, and an application of the extended Kalman filter (EKF) gives the vessel track. Since each sensor has a local clock that operates asynchronously, the time series received by multiple sensors are first synchronized with one another by measuring a sequence of impulses played at the beginning of the recording. The algorithm detects a moving boat by the increase in the broadband sound level and confirms it by extracting the amplitudes at harmonic frequencies due to the propeller movement. To calculate the time delay of arrival, the boat-present signals are divided into small segments that are cross-correlated with signals received by other sensors. Thresholding and clustering are introduced to extract multiple tracks from the cross-correlation. The EKF is trained using the estimated time delays to provide the vessel track. The algorithm has been successful with Bellhop simulated boat signals and field data collected on the Willamette River and Columbia River in Oregon. Limiting factors such as network topology and sensor movement during deployment are also investigated. [Work sponsored by the Nature Conservancy.]
A direction-selective filter with a rational beam pattern
Authors: Schmidlin Dean J.
Published: October 2011

Presented in this paper is a direction-selective filter whose beam pattern is a rational function of a direction cosine. First, a plane-wave sinusoidal pressure function is converted from a 4-D function to a 2-D one by restricting the spatial points to lie on a radial line extending out from the origin in a prescribed look direction. The 2-D pressure function is then input into a linear filter characterized by a second-order partial differential equation with constant coefficients. The natural and forced responses are determined from which expressions for the beam pattern of the filter and the time constant of the natural response are found. The beam pattern is the reciprocal of a second-degree polynomial function of the direction cosine of the plane wave. It is shown that the frequency range over which the integrity of the beam pattern is maintained is a function of the natural response of the filter. An example is presented which illustrates the directivity index that is achievable in contrast to that of a vector or dyadic sensor, both of which have beam patterns that are polynomial functions of a direction cosine.
Multiview, multimodal fusion of acoustic and optical data for classifying marine animals
Authors: Roberts Paul L. D. , Jaffe Jules S. , Trivedi Mohan M.
Published: October 2011

Multiview, multimodal acoustic and optical sensor data can be used to improve our ability to remotely classify marine fish and zooplankton. A key advantage of these data is that by capturing more views of a subject, they are more robust to unknown orientation or pose. In this regard, these data offer significant advantages over singleview, unimodal sources. However, they require additional processing to combine data sources together to render a final classification. Here, a fusion algorithm based on combining data sources at the classification probability level (decision fusion) using confidence-weighting with feedback is investigated. This algorithm uses support vector machines as the underlying classifiers can incorporate any number of views or modalities on the fly and is in general independent of the underlying data source. In addition, the algorithm is able to favor views or modalities that are more discriminant without any a priori knowledge. The algorithm is tested on an array of problems related to classifying fish from broadband acoustic scattering and classifying zooplankton from broadband acoustic scattering and optical images. In all cases, the algorithm yields significant (more than 50%) reductions in error by fusing multiview, multimodal data.
Applications of rhythm algorithm for periodic broadband signals
Authors: Ekimov Alexander
Published: October 2011

Rhythm algorithm, recently published in J. Acoust. Soc. Am. 129(3), 2011 was developed for any periodic broadband signals. This algorithm was applied in human and animal footsteps studies for signals from a node of orthogonal sensors and for underwater signals of sperm mammals clicks measured with hydrophones. Some new applications of this rhythm algorithm are presented and discussed. The rhythm algorithm was applied for water breaking waves on a lake shore. The signals were from a node of two orthogonal sensors placed on the lake shore. This node had a narrow band ultrasonic microphone and a Doppler sonar unit. The narrow band ultrasonic microphone showed detectable levels of ultrasonic signals for breaking waves while Doppler sonar showed maximum wave velocities. Signals from this node were recorded and processed simultaneously with the rhythm algorithm. Another application of this rhythm algorithm for music periodic sound is presented also. In this case, it was possible to see the music rhythms and variations of these rhythms with time using short term Fourier transform.
Dynamic tomography of a gravity wave at the interface of an ultrasonic fluid waveguide
Authors: Bonneau Lenaic , Marandet Christian , Roux Philippe , Nicolas Barbara , Mars Jérôme
Published: October 2011

Based on single-scattering effects, the diffraction-based sensitivity kernels which make the link between the acoustic perturbations and the medium fluctuations have been extensively studied. This research has been recently extended to perturbations at the air–water interface in an ultrasonic waveguide that scales down with a 1-km-long, 50-m-deep ocean acoustic channel in the kilohertz regime. Using array processing between two source-receiver arrays, the sensitivity kernel for both time and amplitude has been experimentally measured and theoretically calculated for each acoustic echo reverberated in the waveguide in response to a small and local surface elevation. In the present work, an ultrasonic experiment is performed during which the waveguide transfer matrix between the source-receiver arrays is recorded 50 times per second while a low-amplitude gravity wave is generated at the water–air interface. The acoustic inversion performed from the surface sensitivity kernels permits to follow the gravity wave dynamics at any point of the surface between the source and the receiver arrays.
Variable acoustics systems and their impact on concert platforms
Authors: Brooks Todd L. , Abercrombie Clemeth L. , Pape Nathan A. , Doria Damian J. , Nakajima Tateo
Published: October 2011

The modern purpose-built concert hall must accommodate an extremely wide range of program, ranging from unamplified solo and chamber music to large-scale symphony and amplified events. Adjustable systems designed for both acoustical and functional flexibility are essential to adapt the stage platform environment to the needs of these different performance types. The successful modern concert hall may include adjustable overhead canopies, adjustable absorption systems, orchestra riser platforms (possibly mechanized), chorus riser wagons, and platform extension/reduction lifts. We will share our experiences and some lessons learned in a variety of recently completed and in-construction projects. Audible differences resulting from differences in architectural contexts will be discussed. We will link possible correlations between aural variations and objective measures with subjective attributes important to the performers.
Feasibility of converting a conference hall to a music performance hall
Authors: Cheung L. Y. , Tang S. K.
Published: October 2011

A 3-D-simulation for improving the acoustics in a conference hall was done. This aimed at investigating the possibility of converting it for musical performance. A room modeling software, Odeon, was used to simulate the effects of adding varies reflectors on the stage with its existing demountable acoustic shell. The following cases were put into simulations: a bare stage, stage with demountable acoustic shell, and stage with acoustic shells with various hanging reflectors above the stage. The additional hanging reflectors with the existing acoustical shell reduce the reverberation time in the hall in most of the cases simulated; however, they increase the average energy levels in the hall. The acoustical shell with the reflector gives a larger energy ratio in average across the octave bands that make the hall more suitable for musical performance. [L. Y. Cheung is supported by the Hong Kong Polytechnic University.]
Technical Committee on Architectural Acoustics short course presentation material
Authors: Hoover K. Anthony
Published: October 2011

The Technical Committee on Architectural Acoustics (TCAA) is a Registered Provider in the American Institute of Architects (AIA) Continuing Education System (CES). The TCAA has developed a standardized introductory short course for architects, called “Architectural Acoustics.” An architect can earn one continuing education unit by attending this short course, if it is presented by a qualified member of TCAA. The course covers topics in sound isolation, mechanical system noise control, and finish treatments. This paper will cover the course material in order to prepare and qualify potential presenters. In order to qualify as an authorized presenter for this AIA/CES short course, attendance at this workshop and membership in TCAA are required.
Exploring the use of acoustics as a tool in male elephant/human conflict mitigation
Authors: O'Connell-Rodwell Caitlin E. , Erckie Rehabeam , Kilian Werner , Wood Jason D. , Kinzley Colleen , Rodwell Timothy C. , Poole Joyce H.
Published: October 2011

Elephant/human conflict mitigation solutions have been explored with varying degrees of success. We present findings on a potential acoustic tool to reduce negative outcomes of male elephants entering agricultural areas in the region northeast of Etosha National Park, Namibia. We monitored elephant traffic within and outside the park boundary using GPS collars on five male elephants with known hormonal status as well as information on the frequency and location of fence breaks. Male elephants in the hormonal state of musth have an increased range, often extending outside the protected area. We explored the feasibility of attracting musth males away from potential conflict areas noninvasively, using estrus calls. We played back estrus calls to known individual subadult (n = 9) and adult musth (n = 9) and nonmusth (n = 6) male elephants and show that adult musth and subadult nonmusth males were much more likely to respond and approach the source than nonmusth adult males (p = 0.029 and p = 0.009, respectively) with an equal level of intensity (p = 0.822). Our findings suggest that the use of acoustics may serve as an effective tool in noninvasive male elephant/human conflict mitigation, depending on the age and hormonal status.
Distribution pattern of finless porpoises at the junction of the Yangtze River and Poyang Lake observed by towed passive acoustic device
Authors: Kimura Satoko , Akamatsu Tomonari , Li Songhai , Dong Lijun , Wang Kexiong , Wang Ding , Arai Nobuaki
Published: October 2011

The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is an endangered freshwater porpoise subspecies unique to the Yangtze River basin. Without immediate conservation measures, it could soon become extinct, just as the Yangtze River dolphin (baiji, Lipotes vexillifer). We report seasonal change in the local distribution of the porpoises living in the conjunction area of the middle reaches of the Yangtze River, side streams, and appended Poyang Lake. A towed stereo acoustic data-logger, A-tag, was used to detect echolocation signals and sound source bearing angles. The independent sound source directions provided the number of animals present, not just the number of sounds. Passive acoustic surveys were performed regularly from May 2007 to August 2010. The water level was highest in August (summer) and lowest in February (winter) and at mid-level in May (spring) and November (autumn). The average number of porpoises detected in 11 surveys conducted in different seasons varied from 0.53 to 1.26 individuals per km. No significant trend of reducing number of porpoises was detected during 3-y monitoring. The distribution of the porpoises was seasonally site-specific. In May and August, the animals were detected more often at river junctions than in the lake, but vice versa from November to February.
Underwater acoustics and acoustical oceanography
Authors: Kuperman William A.
Published: October 2011

Though underwater acoustics (UW) and acoustical oceanography (AO) have different goals, their overlap often makes efforts in these areas indistinguishable. In this talk I emphasize their similarities while also discussing their different approaches. Topics to be briefly covered in this review will include the environmental acoustic aspects of propagation, noise, and inversion with examples from modeling and experiments. Among the interesting outcomes of the differences between these fields is that the emphasis on inversion in AO has increased the accuracy requirements for UW.
Transthoracic in vivo measurements of porcine myocardial viscoelasticity using Lamb wave dispersion ultrasound vibrometry
Authors: Nenadic I. Z. , Urban M. W. , Pislaru C. , Greenleaf J. F.
Published: October 2011

Diastolic dysfunction is characterized by the stiffening of the left-ventricular myocardium. An imaging technique capable of quantifying viscoelasticity of the left-ventricle would aid clinicians in evaluating diastolic function. Lamb wave dispersion ultrasound vibrometry (LDUV) is an ultrasound-based method for measuring viscoelasticity of plate-like materials by exciting Lamb waves and measuring change of wave velocity as a function of frequency (dispersion). Lamb wave dispersion equation is fit to the dispersion data to estimate mechanical properties. We report in vivo transthoracic studies aimed at quantifying elasticity and viscosity of a beating porcine left-ventricle using LDUV. A single ultrasound probe operating at 5 MHz was used for impulse excitation in the myocardium and to track the wave motion. A Fourier space-time analysis of the motion was used to obtain Lamb wave velocity dispersion. ECG-gated transthoracic in vivo measurements of group velocity, elasticity, and viscosity throughout a single heart cycle were obtained. Group velocity, elasticity, and viscosity in the frequency range from 50 to 500 Hz increased by at least two-fold from diastole to systole, consistent with contraction and relaxation of the myocardium.
Frequency domain calculations of pulse-echo ultrasound signals with the fast nearfield method
Authors: McGough Robert J.
Published: October 2011

Simulations of pulse-echo signals transmitted and received by an ultrasound phased array are evaluated in the frequency domain using FOCUS, and the results are compared with the output of Field II. The frequency domain simulation approach in FOCUS calculates the fast Fourier transform of the input signal, evaluates the individual frequency components of the transmit and receive pressure transfer functions using the fast nearfield method, and then computes the inverse fast Fourier transform of the product to obtain a numerical representation of the received time signal. With this approach, synthetic aperture signals are simulated in Matlab for each pair of transmit and receive elements for three transmit elements and sixteen receive elements. Each element is excited with a 3 cycle Hanning-weighted input pulse with a 3 MHz center frequency. The temporal sampling of the computed signal in FOCUS is 12 MHz. To achieve approximately the same accuracy, Field II requires a temporal sampling of 4 GHz. Examples of simulated radio-frequency signals, the envelopes of these signals, and the associated numerical errors will be demonstrated for each method, and formulas for converting the pulse-echo outputs generated in FOCUS and Field II into equivalent quantities will be shown.
Transducer designs and simulations for high frequency scanning acoustic microscopy for applications in exploring contrast mechanism and the mechanical properties of biological cells
Authors: Juntarapaso Yada , Tutwiler Richard L. , Anastasiadis Pavlos
Published: October 2011

Scanning acoustic microscopy (SAM) has been extensively accepted and utilized for acoustical cellular and tissue imaging including measurements of the mechanical and elastic properties of biological specimen. SAM provides superb advantages: it is a noninvasive method; it can measure mechanical properties of biological cells or tissues; and fixation/chemical staining is not necessary. The first objective of this research is to develop a program for simulating the images and contrast mechanism obtained by high-frequency SAM. Computer simulation algorithms based on Matlab® were built for simulating the images and contrast mechanism. The mechanical properties of HeLa and MCF-7 cells were computed from the V(z) measurement data. Algorithms for simulating V(z) responses involved calculation of the reflectance function and were created based on ray theory and wave theory. The second objective is to design transducer arrays for SAM. Theoretical simulations based on Field II programs of the high frequency ultrasound array designs were performed to enhance image resolution and volumetric imaging capabilities. The new transducer array design will be state-of-the-art in improving the performance of SAM by electronic scanning and potentially providing a four-dimensional image of the specimen. Phased array beam forming and dynamic apodization and focusing were employed in the simulations.
Split domain antiresonance in micromachined lithium niobate
Authors: Ostrovskii Igor , Cremaldi Lucien
Published: October 2011

The micromachined periodically poled LiNbO3 (PPLN) demonstrates acoustic superlattice properties. Different acoustic modes in PPLN wafer have their stop-bands with low FL and upper FU cutoff frequencies. The micromachined transducers based on such structures operate at frequencies near FL and FU; they have a strong domain resonance-antiresonance when acoustic half-wavelength is close to domain length. In this work, we investigate structures with 300- and 450-micron long domains micromachined in a 0.5-mm-thick Z-cut lithium niobate wafer. The metal electrodes are deposited onto multi-domain structures having up to 90 total inversely poled domains. Experimentally, two modes of operation are investigated: (1) acousto-electric current excitation of domain vibrations when rf current passes through the whole multidomain structure and (2) plate-waves excitation and detection at two opposite ends of domain pattern when acoustic vibration travels through the multidomain pattern. In both cases, the split antiresonances are observed, and they are characterized by two main minima coinciding with the FL and FU frequencies. The difference (FL − FU) constitutes the stop-band for propagating zero antisymmetric mode, at which PPLN transducer operates. The experimental data are in agreement with theoretical calculations. Possible application of the split antiresonance effect for micromachined ultrasonic transducers is discussed. [This work is made possible in part due to the research grant “Nonlinear vibrations of piezoelectric resonators,” UM, 2011.]
Hot topics in physical acoustics
Authors: Keppens Veerle
Published: October 2011

Understanding the propagation and interaction of acoustic waves in “unconventional” systems is one of the main focus areas of physical acoustics, where unconventional may indicate that the system is far from thermodynamic equilibrium, poorly understood, newly discovered, or a combination thereof. In this talk, I will attempt to give a few specific examples of recent contributions from the field of physical acoustics to a better understanding of “hot” materials such as Pu and pnictide superconductors. Additional examples from current efforts in physical acoustics will be used to illustrate the breadth of the field and show how physical acoustics is closely tied to many other technical areas within the Society.
Modern tools for improving the development of acoustical standards
Authors: Struck Christopher J.
Published: October 2011

The development of acoustical standards has in the past largely followed on the trailing edge of technology. Given the progressively more rapid development of new technology, it is critical that new standards be developed when needed in the timeliest manner possible. Furthermore, participants in working groups are volunteers with limited time available for this important work. Budgetary constraints may also limit travel to in-person meetings for many persons otherwise interested in participating and whose practical experience is essential to the process. On-line meeting and collaboration tools enable shorter, more effective, and more frequent meetings to move draft standards more quickly to a ballot-ready document. Documents can be edited collaboratively in real time using standard mark-up tools for immediate feedback from participants. This also enables participation across time zones. The use of a password protected “cloud network" ftp site for working group documents (e.g., drafts, reference documents, meeting minutes, etc.) eliminates unnecessary e-mail traffic with large attachments and enables participants to access documents at any convenient time. These tools will be described and demonstrated to show the contemporary standards development process in action.
An equipment manufacturer's perspective of acoustical standards
Authors: Lind Stephen J.
Published: October 2011

As an HVAC manufacturer, it is our goal to create safe, comfortable, and efficient environments (i.e., classrooms, health care facilities, offices, etc.). Standards are useful in gaining agreement regarding the appropriate sound levels for these spaces and establishing how to verify that these levels are met. Regular interaction and participation in writing the standards helps to ensure that all are aware of the requirements and it also allows participants to provide input on what is practical. Participating in the process also helps to prevent adversarial relations between the parties involved in the design and use of the equipment. Standards also provide the technical basis for which manufacturers and customers can make a valid comparison of different products. The information provided is useful in the design process. Sound power of the equipment is a commonly used metric. Standardizing sound power measurement methods reduces the customer's risk by making sure the published sound levels are representative of the equipment as it is intended and gives a defined expectation of repeatability. Thus, participating in the standards process, we help to ensure that the measurement methods are practical for the intended equipment.
The influence of noise on speech intelligibility
Authors: Jones Hillary , Neilsen Tracianne B.
Published: October 2011

When you are listening to speech, a lecture, or a performance, the sound waves travel through the room to reach you. Along the way, the speech sounds interfere with the other sounds in the room such that the sound reaching your ears is often corrupted by noise. The addition of noise decreases the intelligibility of the speech. A series of auditory demonstrations distributed by the Acoustical Testing Center at NASA Glenn Research Center let you hear how the speech intelligibility decreases as the amount of external and internal noise in a lecture hall, classroom, or workplace increases.
Hands-on demonstrations for Project Listen Up: Education outreach part III
Authors: Nardini Amie E. , Blackburn Jacqueline , Korman Murray S.
Published: October 2011

Midshipmen will be getting involved in an ASA education outreach effort by presenting or recording a number of acoustical demonstrations geared to promote a hands-on learning experience for middle- and high-school age girl scouts. This is an extension of the demonstration effort and outreach presented at the ASA Meeting held in Baltimore in 2009 and Seattle in 2011. The demos are designed to visualize certain wave effects that will be explained by the Midshipmen “live” or by computer video. The participants will be free to explore, control the apparatus, and make their own scientific discoveries. The hands-on demonstrations will include (1) a ripple tank with two separated periodic point sources or a plane wave source driver for wave studies, (2) an ultrasonic motion sensor for measuring and displaying displacement, particle velocity and acceleration of an oscillating object or a person's motion, (3) tuning forks matched to Helmholtz resonators, and (4) a driven clamped circular plate supporting a column of dry sifted masonry sand (or uncooked rice or grass seed) for studying the resonant frequency versus. granular mass loading.
Soundscape study methods of band rehearsal room
Authors: Tsaih Lucky
Published: October 2011

Soundscape study methods were applied to a band rehearsal room to understand the acoustical issues involved in this situation. A taxonomy of sound sources, direct observation to identify the specific sonic events and the multiple source and receiver paths involved in the complex listening and performing tasks that occur during band rehearsals were identified. It was found that students spend almost 1/2 of their rehearsal time involved with verbal instruction and discussion. Interviews with conductors and questionnaires administered to music students in three different band rooms were used to determine what musicians are listening for during rehearsals. Source and receiver combinations for physical acoustical measurements were located to study the multiple listening tasks identified in the questionnaires. Musicians were constantly trying to “hear each other” for intonation, rhythm, dynamics, articulation, and tone quality during rehearsals. Statistical models linking the qualitative results of the questionnaires with the acoustical measurements and architectural features of the rooms show that the ceiling height, room volume, area of sound diffusing surfaces, low frequency sound level, early reflected sound energy, and reverberation were related to the ability of musicians to hear each other and the detailed attributes of music.
A proposed method of data collection and analysis for soundscape-based noise evaluation
Authors: Bettcher Adam D.
Published: October 2011

As an information-rich means of describing and accessing a particular aural environment, soundscape analysis requires additional types of information beyond those used for energy-average and statistical methods of noise evaluation. Managing the flow of data from different types of measurements is crucial in providing a meaningful description of the sonic landscape of a site. The proposed method of data collection and processing produced a means of describing the aural environment with quantitative descriptors from analysis of simultaneously recorded sound level measurements and sound recordings. Sound recordings were analyzed to determine the makeup of a soundscape comprised of individual sounds. The sounds were organized into a taxonomy; and analysis of frequency of occurrence, sound levels, and spectra of each sound, duration of each sound, and the rate of change of each sound were conducted to quantitatively describe the elements of the sonic landscape. This method of data analysis was applied to a soundscape study and produced information that exceeded the abilities of sound-energy measurements alone in providing helpful quantitative descriptors for qualitative soundscape analysis.
Soundscape collaboration for science, management, and public outreach at a national historic site
Authors: Maher Robert C. , Ford Christine
Published: October 2011

Scientists and engineers involved in soundscape research at national parks and historic sites have the opportunity to collaborate with park management and public outreach professionals. The technical and signal processing considerations of the acoustician can complement the management and regulatory considerations of the park supervisors and the public awareness and outreach efforts of the professional staff and interpretive rangers. The triad of science, policy, and outreach involves all of the key stakeholders in soundscape assessment and evaluation. Examples of collaborative activity at a U.S. National Historic Site are presented.
Comparing data collection and processing options for terrestrial acoustical monitoring addressing long durations and large spatial scales
Authors: Fristrup Kurt M.
Published: October 2011

For generations, skilled naturalists have listened attentively to expand the scope of their field searches and surveys. The rapid proliferation of digital audio recorders with large storage capacity and low power consumption offers numerous options to pursue standardized acoustical surveys of several weeks duration across large areas. This presentation will assess a representative sample of available equipment in relation to the parameters determining their suitability for these applications: price, capacity, fidelity, and ancillary features. Enormous data collection capacity is not useful unless there are adequate tools for processing the data to render the necessary results. The features and performance of several software packages will be compared in the context of different classes of potential application. In particular, the merits of highly selective detectors will be discussed in relation to the alternative of more permissive screening for potentially interesting sounds followed by a measurement and clustering or classification process.
Long-term mapping of red grouper sound production on the West Florida Shelf
Authors: Wall Carrie C. , Lindemuth Michael , Simard Peter , Mann David A.
Published: October 2011

While it is widely known that numerous fish species produce sound, discerning when and where is more challenging. Through the use of autonomous passive acoustic technology, the spatial and temporal patterns of fish sound production, namely red grouper Epinephelus morio, in the eastern Gulf of Mexico were documented. Two methods have been employed off west-central Florida: moored passive acoustic arrays deployed in 2008 and 2009 covering over 16 600 km2 from the coast to 100 m deep, and autonomous gliders with integrated hydrophones deployed cross-shelf for up to 4weeks. Over four million acoustic files generated from these methods were analyzed using DSGLab, an open-source database and data analysis system implemented using Matlab and MySQL. An automatic detection algorithm was created and implemented in DSGLab to determine the presence of red grouper calls. False detections were removed manually and the results were analyzed to determine diel and seasonal variability of red grouper sound production in addition to identifying the range of red grouper in the eastern Gulf of Mexico. Support was provided by the University of South Florida, Center for Ocean Technology glider staff, and the captains and crew of the R/Vs Weatherbird II, FishHawk, Eugenie Clark, and Allicat, and the M/V Narcosis. This research was funded by NOPP (OCE-0741705) awarded to DM and the USF/USGS Graduate Assistantship awarded to CW.
Quantified lysis of cell-like lipid membranes due to nanoparticle-facilitated cavitation
Authors: Benchimol Michael J. , Ibsen Stuart D. , Simberg Dmitri , Wu Zhe , Mattrey Robert F. , Esener Sadik C.
Published: October 2011

Certain nanoparticles act as nucleation sites for acoustic cavitation. Their surface roughness and hydrophobic regions can decrease the pressure required to induce the cavitation event. This concept has been examined for potential to provide a sensitizer for high-intensity focused ultrasound (HIFU), where cavitation can be beneficial. While passive cavitation detection can accurately determine the pressure threshold, variations in acoustic impedance/backscatter from different nanoparticles can make it difficult to normalize the amount of cavitation and determine the precise magnitude of the physical consequences. Here we demonstrate a method to determine the extent of lysis of lipid membranes using liposomes loaded with a self-quenching fluorophore. Lysed liposomes released the fluorophore, causing an increase in the fluorescence signal. Liposomes were mixed with the nanoparticles and insonated with a HIFU transducer at physiological temperature. The pressure threshold for dye release was measured for a panel of nanoparticles. Nearly complete release of the dye was achievable in all cases, but it required higher pressures in the absence of nanoparticles. In addition, we measured the effect of a viscous medium, which is more representative of certain physiological states. Furthermore, the encapsulation of the nanoparticle within a liposome can create a platform delivery vehicle for anti-cancer therapeutics.
Ultrasound-induced temperature elevation for in-vitro controlled release of temperature-sensitive liposomes
Authors: Mannaris Christophoros , Efthymiou Eleni , Escoffre Jean-Michel , Bouakaz Ayache , Meyre Marie-Edith , Germain Matthieu , Averkiou Michalakis A.
Published: October 2011

Drug loaded temperature-sensitive liposomes (TSLs) release their payload with mild hyperthermia near their phase transition temperature (Tm = 43–45 °C). Such a release may improve therapeutic efficacy and reduce toxic side effects in cancer treatment. In the present work, two different approaches are considered where focused ultrasound is used to induce the required temperature elevation for the release of doxorubicin from TSLs: (a) primary heating due to thermo-viscous absorption of ultrasound in absorptive media (oil, glycerol) and (b) secondary heating in non-absorptive media (blood, cell medium) due to heat transfer from the surroundings. Fine-wire thermocouple readings where in close agreement with theoretical predictions of temperature elevation with the Bioheat equation. Pulsing schemes to elevate and maintain the temperature at the desired value were designed with the Bioheat equation and validated with experiments. Fluorescence spectroscopy was used to assess the release of free doxorubicin that exhibits higher fluorescence intensity than the liposomal formulation. Significant drug release was achieved with both approaches.
Experimental characterization of dye-loaded echogenic liposomes
Authors: Paul Shirshendu , Russakow Daniel , Rodger Tyler , Sarkar Kausik , Nahire Rahul , Mallik Sanku
Published: October 2011

Liposomes are submicron sized vesicles with a lipid bilayer encapsulating an aqueous phase inside. Due to their favorable properties like longer circulation time, lesser toxicity, and greater uptake, they are a prime candidate for drug delivery. Recently, they are being specially prepared so as to encapsulate air, making them good scatterers of ultrasound wave. These echogenic liposomes, therefore, can be used both for ultrasound contrast imaging and drug delivery. We will report in vitro attenuation and scattering measurement from echogenic liposomes loaded with carboxyfluorescein (used as a surrogate for small molecular weight drugs). The results will be compared with non-dye-loaded ones. Effects of dye loading and presence of bovine serum albumin (BSA) on size distribution, echogenicity, and release characteristics will also be discussed.
Energy conversion through thermoacoustics and piezoelectricity
Authors: Keolian Robert M. , Backhaus Scott
Published: October 2011

Waste or prime heat can be converted into electricity with thermoacoustic-Stirling engines coupled to piezoelectric alternators. An inline arrangement of engines and alternators allows a vibration balanced, multiphase power generator that is compact, light weight and low cost. The engines convert heat into high amplitude ≈400 Hz oscillations in pressurized helium gas. These pressure oscillations cause a thin steel diaphragm to flex like a drumhead. The diaphragm is supported at its perimeter by a ring of piezoelectric elements. As the diaphragm flexes in either direction, it pulls inward on the piezoelectric elements causing a large amplified ≈800 Hz fluctuating compressive stress in the elements which then convert the stress into electricity with high efficiency. The flexible-diaphragm piezoelectric alternator overcomes the large acoustic impedance mismatch between the helium and piezoelectric elements without exceeding the limited fatigue strength of available materials. So far, a prototype generator has produced 37 W, and is being modified to produce 600 W. Also, a project is underway to recover 7 kW peak electrical power from the exhaust of an over-the-road heavy-duty diesel truck. The generator appears scalable up to megawatt power levels. [Work supported by DOE, ONR, Clean Power Resources, Innovation Works, and Applied Research Laboratory.]
Improved spiral-wavefront transducer for underwater acoustic navigation
Authors: Brown David , Aronov Boris , Bachand Corey
Published: October 2011

Spiral-wavefront transducers have received recent attention as enabling elements in phase-based underwater navigation systems, whereby the signaling transducer launches a diverging wave that is omnidirectional by magnitude but linearly phase-biased with azimuthal angle. The detected signal is compared with a control signal having constant phase to allow the unique determination of bearing angle. Range can be determined by time-of-flight. While such systems are used in air traffic control navigation, the transition to underwater acoustics had only emerged with the advent of increased unmanned underwater vehicle traffic (Dzikowicz and Hefner). Analytical and experimental test results, including beam patterns, TVR, and power factor, are presented for resonance operations at 25 kHz (c-band). [Work supported by BTech Acoustics LLC.]
Calculation of Helmholtz frequency of a Renaissance vihuela string instrument with five tone holes
Authors: Bader Rolf
Published: October 2011

A replica of the historical Guadalupe vihuela, a Renaissance string instrument was investigated. As it has five sound holes a formula was developed to calculate its Helmholtz frequency radiated from these five holes. Therefore, using a 128-microphone array, the radiation pattern at the Helmholtz frequency of 138 Hz was measured showing strong radiation at the holes near the center of the body and lower radiation at the holes near the upper top plate boundary. Calculating a mean radius from the single radii and weighting them with their radiation strength, the measured Helmholtz frequency is calculated correctly. This is not the case when including the ornamentation of the sound holes into the calculation which indeed cover 65% of their area. Additionally, the overall radiation from the different top plate parts of this vihuela was compared to that of another much smaller vihuela and those of a classical guitar showing the Guadalupe replica to have a very large frequency range of strong sound hole radiation up to 500 Hz, where the classical guitar is stronger in the bass but its sound hole radiation part is restricted to lower frequencies. This makes the vihuela a mixture between a guitar and a lute.
Effects of diffraction for acoustic loads on building structures
Authors: Sutherland Louis C.
Published: October 2011

Acoustic loads on building structures from external noise are influenced by acoustic diffraction of the incident wave front. An experimental study by Wyle Labs of diffraction consisted of measurements on a solid ground-mounted cubical obstacle insonified by approximately plane waves. The diffraction effect is equal to the sound level at various positions on the cube relative to the free field sound level. The former was measured with a microphone mounted flush with the surface of the cube. As expected, the diffraction effect varied systematically with the ratio of the cube side to wavelength and is portrayed by contours of equal diffraction correction. The maximum correction was equal to or more than the expected 6 dB near the center of the side facing the source but also exceeded 6 dB near the center of the back (shadow) side of the cube when the ratio of cube side to wavelength is close to 1. This positive diffraction correction may not normally be considered in assessment of noise on the shadow side of buildings. The experimental data are shown to be consistent with diffraction theory for a single cube. Theoretical predictions of diffraction effects for spherical and cylindrical obstacles are also shown.
Effects of ground impedance on large rocket motor noise measurements
Authors: Pilkey Debbie , Kenny R. Jeremy , Haynes Jared
Published: October 2011

Free field acoustic measurements have been collected on large solid rocket motors at the ATK test facility in Promontory, Utah. Ground effects have been measured to understand the impact on the overall data collection effort. Ground effects were measured at two test stands with vastly different terrain that hold the reusable solid rocket motor (RSRM) and RSRMV (five-segment RSRM) static test motors. Techniques for measuring and understanding ground effects are investigated, and examples presented from two different methods.
Statistical analysis of a characteristic shock formation distance for high-amplitude noise
Authors: Muhlestein Michael B. , Gee Kent L.
Published: October 2011

Previous research involved investigating a characteristic shock formation distance for Gaussian, finite-amplitude noise propagating in a cylindrical plane wave tube [Muhlestein and Gee, POMA 12, (in press)]. In particular, the evolution of the probability density function of the pressure and the first-order time derivative of pressure along with the skewness of the pressure derivative were experimentally studied. It was concluded that a constant-factor modification to the nonlinear distortion length defined by Gurbatov and Rudenko may yield a suitable characteristic shock formation distance in a statistical sense. Additional Gaussian noise data with a broader frequency range have now been taken, and the effects of boundary layer dispersion considered. Furthermore, noise with other statistical distributions and pressure statistics mimicking high velocity jet noise have been examined. These data are analyzed statistically as before using probability density function estimates and the skewness of the pressure derivative. An additional figure of merit, the characteristic number of shocks per zero crossing, is also examined.
Non-adiabatic geometric phase of elastic waves
Authors: Boulanger Jeremie , Lebihan Nicolas , Catheline Stefan , Rossetto Vincent
Published: October 2011

We study the transport of elastic waves in a waveguide with helical shape. Polarization exhibits a geometric phase (or Berry phase): The polarization plane rotates along the helix following a geometric rule called parallel transport. Whereas this experiment is similar to the first experimental evidence of a Berry phase, by Tomita and Chiao [Phys. Rev. Lett. 57 (1986)], there is a major difference: The evolution of polarization is not adiabatic. This experiment therefore addresses the universality of the geometric phase beyond the adiabatic regime. We show that properties of the observed geometric phase coincide with the ones predicted by the adiabatic theory. The measured value of the phase is consistent (up to experimental uncertainty) with the theoretical value and no dependency with frequency is observable either.
Triggering of self-excited thermo-acoustic oscillations in a Rijke tube with a premixed laminar flame
Authors: Zhao Dan
Published: October 2011

For a given Rijke tube, self-excited combustion oscillations could be caused by the transient growth of flow disturbances. A premixed laminar flame, anchored to a metal gauze, is considered to investigate the role of non-normality and the resulting transient growth in triggering such oscillations. The unsteady heat release is assumed to be caused by the flame surface variations, which results from the fluctuations of the oncoming flow. The flame is acoustically compact and its presence causes a jump in mean temperature. Coupling the flame model with a Galerkin series expansion of the acoustic waves enables the time evolution of the flow disturbances to be calculated. It was found that the nonlinear model can predict the mode shape and the frequencies of the excited oscillations very well. Moreover, the fundamental mode with the lowest frequency is the easiest one to be excited among all the acoustic modes. Linearizing the model and recasting it into the classical time-lag formulation provide insights on the mode selection and triggering. Finally, to gain insight about the stability behaviors of such non-normal Rijke tube, pseudo-spectra analysis is performed to obtain upper and lower bounds on the transient growth factor.
Word production analysis of native speakers and second language learners by phonemic and categorical verbal fluency test
Authors: Asano Keiko
Published: October 2011

This study investigated how different Japanese, Arabic, and Thai second language learners produce words orally from their native languages aspects of the Verbal Fluency Test. This test, which is in wide spread use in clinical and neuropsychological assessments, consists of two different tasks: phonemic and categorical sections. As a phonemic procedure, the participants were to produce orally as many different words as possible beginning with a certain letter within one minute. The names of specified items within categorical one were to be produced. These clinical field scores are only adopted as quantitative information. However, in this study, the relationship between the phonemic and categorical sections is also analyzed to evaluate the ability of second language learners' word production. It is commonly known that normal and healthy native speakers can produce more words in categorical section than that of the phonemic one while the speakers who are clinically disordered have results that are the reverse. The results show that native speakers produce more categorical words, which were the same results found in normal and healthy people. However among all three second language learners, there is different tendency. Categorical words were produced less frequency with no relevance to the proficiency level. The implication for the function of different brain area activation will also be discussed.
Physiological arousal and laughter acoustics
Authors: Amoss R. Toby , Martin Noel B. , Owren Michael J.
Published: October 2011

Laughter is a ubiquitous human phenomenon that has been little investigated scientifically. To examine the relationship between laugher arousal level and acoustic output, bouts of laughter were recorded from undergraduates viewing humorous video clips. These participants provided continuous subjective ratings of funniness while watching the clips, and heart rate (HR) was collected concurrently to provide an objective measure of physiological arousal. As a first approach, comparisons focused on voiced laughter from nine males and eight females. For each individual, one high-amplitude and one low-amplitude laugh bout was identified for which HR could be extracted. Beats per minute increased significantly more with high-amplitude than low-amplitude bouts, an effect that was not likely due to physical exertion or movement artifact. No sex difference was found in the magnitude of HR change for either amplitude condition. Both subjective ratings of funniness and fundamental-frequency measures were significantly higher for higher-amplitude bouts, while harmonic-to-noise ratios trended lower for these sounds. Overall, results are consistent with the intuition that higher physiological arousal in vocalizers is reflected in higher vocal amplitude and faster, potentially less stable vocal-fold vibration in voiced laughter.