bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduced order modeling for the skin panels of hypersonic vehicles and nonlinear normal modes
Authors: Allen Matthew S.
Published: November 2013

The skin panels on concept hypersonic (Mach > 5) vehicles are subjected to intense acoustic and thermal loading. As a result, nonlinear structural dynamic models are needed to predict their response with the required level of accuracy. Vehicles such as this carry a large amount of fuel and so the structure must be very light if the overall vehicle is to meet its performance requirements. This talk will discuss the reduced order modeling frameworks that are being used to create models for these types of structures and discuss how nonlinear normal modes are being used to understand how the structure’s response changes with the loading amplitude. Nonlinear modes are also being used to evaluate the reduced order models in order to predict the frequency bandwidth and the range of forcing amplitude over which they will be valid. This approach allows the analyst to develop a considerable level of confidence in the reduced order model without having to compute time responses of the full nonlinear finite element model; time response simulations are far too expensive to be used in practice on the structures of interest.
Low noise blower fan for heating and cooling applications
Authors: Liu Yi , Wang Percy
Published: November 2013

A new low noise fan called foam blower fan is presented here for low noise heating, ventilation, and air conditioning (HVAC) applications. Traditional HVAC blower fans are made of discrete metal or plastic fan blades, which generate blade tonal noise when each blade interacts with blower cut-off or other housing structures. It is proposed here that foam wedge (porous media) is inserted between blades at strategic locations, to reduce the tonal noise generation. It is analytically and experimentally demonstrated in this paper that the proposed new foam fan can reduce discrete tonal noise at various operating speeds.
Industry tubing characterization method for fixed speed applications
Authors: Liu Yi , Shen Yufeng
Published: November 2013

Efforts for structural tubing characterization are presented here for HVAC industry fixed speed applications. Structural tubing is a type of metal connector typically with hollow circular or rectangular cross-sections. Copper tubing is widely used in HVAC industry to transfer refrigerant between compressors and condensers. However, when the natural frequencies of tubing system are at the running speeds of the compressors; design life of the product is reduced. Therefore, tubing configuration structural change is needed to shift these problem frequencies. Traditionally, industry has been using finite element method and vibration tests to identify the critical geometric parameter for frequency shift. New efforts are been proposed here to present designer a sensitivity study tool to identify these critical parameters quickly, therefore, shorten the design cycle time.
Perception of acoustically similar vowels from English and Hebrew
Authors: Morris Richard J. , Shames Yonit A.
Published: November 2013

The formant theory suggests that vowels are differentiated perceptually based on the presence of concentrated bands of harmonic energy in the vowel's acoustical signal. Vowels from different languages often contain formants with similar configurations, but it is unclear what effect cross-language variations have on the perception of the vowels. This study was completed to find when English-speaking listeners are able to differentiate between vowels spoken in two languages, General American English and Modern Hebrew. Natural vowels in kVp syllables were recorded and acoustically normalized using the Bark scale. The English and Hebrew vowels were paired in test groups based on the normalized formant values and the fundamental frequencies of the speakers. Listeners designated each pair as “same” or “different.” It was hypothesized that listeners were more likely to differentiate between the vowels in English-Hebrew pairs than in same-language pairs, and that they were more likely to differentiate between vowels with higher Bark scale differences. However, Bark scale differences did not always match perceived differences. Listeners demonstrated the least difficulty discriminating between different-language pairs containing /e/ and /o/ (60–90% accuracy), more difficulty for English /ɑ/ and Hebrew /a/ (40–80% accuracy), and the most difficulty for /i/ and /u/ (10–60% accuracy).
Phonetic and orthographic cues are weighted in speech sound perception by second language speakers: Evidence from Greek speakers of English
Authors: Giannakopoulou Anastasia , Uther Maria , Ylinen Sari
Published: November 2013

Speech-sound contrasts that have multiple phonetic cues can be particularly difficult for foreign-language learners especially if the cues are weighted differently in the foreign and native languages (e.g., Giannakopoulou et al., 2013). The orthographic representation of words is suggested to also interfere with speech sound perception in way of presenting additional cues for the second language learner. In order to examine the possibility that orthographic representation of the word stimuli provides additional cues, this study explores perceptual identification with the use of pictures as visual stimuli. Greek child and adult speakers of English were studied to determine on what basis they are making perceptual identification between English vowels. One task involved the use of minimal pairs in their orthographic form (word stimuli), another task used relevant pictures that resembled the meaning of the respective words. The auditory stimuli used in both task types were identical. Performance was impaired for Greek speakers across all tasks but worst for Greek speakers for the picture stimuli task. Interestingly, child Greek speakers performed significantly worse in the picture stimuli task, even though a picture translation control task revealed high performance. These results are discussed in terms of the strategies used to acquire new languages.
Evidence for cognitive restoration of time-reversed speech by a language-trained chimpanzee (Pan troglodytes)
Authors: Heimbauer Lisa A. , Beran Michael J. , Owren Michael J.
Published: November 2013

Previously, we reported on the ability of Panzee, a language-trained chimpanzee, to identify sine-wave and noise-vocoded speech by attending to the amplitude and frequency modulations in the altered signals. Here, we report on her ability to perceive phoneme-length information in words reproduced in time-reversed form. While this manipulation preserves the amplitude of frequency components, it reverses the pattern of energy changes within each reversal window. Listeners easily recognize speech at reversal windows up to 100-ms length, but at longer reversal lengths unintelligibility begins to occur (Saberi and Perrott, 1999). The theoretical interpretation is that individual phonetic segments range from 50 to 100 ms (Crystal and House, 1988), and reversal-windows less than 100 ms provide for restoration of phoneme perception. Hypothesizing that Panzee also perceives speech based on phonemic segments, we tested her and humans with words in eight reversal forms ranging from 25 to 200 ms. Results revealed time-reversal window length significantly predicted percentage-correct word identification for Panzee and the humans. Additionally, window lengths exceeding 100 ms produced partial word intelligibility, with 50% intelligibility occurring at approximately 130 ms for both species. We therefore conclude that Panzee attends to phoneme-related cues in time-reversed speech, and hence in natural speech.
Perceptual compensation with familiar and unfamiliar rounding coarticulation
Authors: Johnson Keith , Kang Shinae , Cibelli Emily
Published: November 2013

We compared the integration of three kinds of contextual information in the perception of the fricatives [s] and [∫]. We asked American English listeners to identify sounds on an [s] to [∫] continuum and manipulated (1) the vowel context of the fricative ([Ce], [Co], [Cœ]), (2) the original fricative of the CV ([s] vs [∫]), and (3) the modality of the stimulus (audio-only, AV). There was a large compensation for coarticulation effect on perception—subjects responded with “s” more often when the following vowel was round. Interestingly, and perhaps significantly, perceptual compensation was not as great with the less familiar vowel [œ] even when listeners saw the face. Measurements of lip rounding in these stimuli show that [o] and [œ] have about the same degree and type of rounding over the CV. In a second experiment, we measured reaction time to audio-visual mismatches in these stimuli (again in a fricative identification task). We found that mismatches of audio and video consonant information slowed reaction time, and that vowel mismatches did as well. However, mismatch between [o] and [œ] did not slow reaction time. These data suggest that linguistic experience and stimulus properties affect perception.
Visual cue salience depends on place of articulation and syllabic context
Authors: Kang Shinae , Johnson Keith
Published: November 2013

This study is on audio-visual perceptual intelligibility of consonants in intervocalic clusters (VC1C2V). Previous studies have yielded inconsistent findings on perceptual salience of different stop consonants and very few have tested salience in clusters. Consequently, it has been unclear as to whether greater or less perceptual salience leads to greater degree of place assimilation. In Korean, labials are often produced with more gestural overlap than velars in C1. I tested whether labials are perceptually more or less salient in both audio and audio-visual conditions. VC and CV syllables spoken by both English and Korean speakers were first embedded in noise and spliced together for non-overlapping VCCV sequences. Korean listeners identified the two consonants in either audio or AV presentations. A confusion matrix analysis for each stop consonant shows that in C1 there is asymmetric improvement with the addition of videos for labial consonants only, while in C2 this asymmetry was not found. The result suggests that listeners make differential use of visual cues depending on place of articulation and syllabic context. Also, the result supports the talker enhancement view of sound change, which assumes that talkers are aware of perceptual salience and enhance (with less gestural overlap) the weak contrast.
Time reversal methods for high frequency multiple-input/multiple-output underwater acoustic communication
Authors: Song Aijun , Badiey Mohsen
Published: November 2013

As a sound focusing technique, time reversal has been utilized in underwater acoustic communication since the 1990s. Here, we particularly study the usage of time reversal methods to separate sounds from different sound sources for high frequency transmissions (greater than 10 kHz), in addition to sound focusing. The separation of sounds creates multiple parallel acoustic links between multiple transducers and a receiver array, thus, providing increased data rates between the source and receiver for communication purposes. It is referred to as multiple-input/multiple-output (MIMO) acoustic communication. Multiple at-sea experiments have been conducted to demonstrate high frequency MIMO signaling and their communication performance. A number of signal processing techniques have been developed in the time reversal framework to enhance the sound focusing and separation that are needed in high frequency acoustic MIMO communication. For example, multi-stage interference cancellation methods have been devised to suppress the co-channel interference and to ensure the sound separation. In this talk, we will show their effectiveness in the presence of water column variability based on our experimental data. An acoustic communication channel model will also be used to explain the impact of environmental variability.
Time reversal communication over doubly spread channels
Authors: Zeng Wen-Jun , Jiang Xue
Published: November 2013

Conventional time reversal can mitigate multipath delay dispersion by temporal focusing. But it is not applicable to time-varying channels with a Doppler spread. Although recently time reversal communication has been adapted to time-variant channels, the modified technique requires frequent channel updates to track channel variations and cannot handle large Doppler spread, which means that it cannot achieve frequency focusing. In this paper, two time reversal receivers for underwater acoustic communications over doubly spread channels are proposed. The proposed approach, which can be interpreted as time-frequency channel matching, is based on the channel spreading function rather than impulse response adopted by the existing techniques; this leads to much less frequent channel updates. Unlike existing methods that only correct a single Doppler shift, the proposed approach uses a rake-like structure to compensate for multiple Doppler shifts and hence can eliminate severe Doppler spread induced by temporal channel variations. Simulation results verify the effectiveness of the proposed approach, indicating that it can simultaneously counteract delay and Doppler spreads, achieving both temporal and frequency focusing.
Invariants of the time reversal operator and characterization of solid media: An overview
Authors: Prada Claire
Published: November 2013

The invariants of the time reversal operators for solid media have been the object of several studies in the past 15 years in the context of multi-element array imaging. These invariants are obtained from the decomposition of the array response matrix. Their analysis was applied to the detection of flaws using bulk waves, or Rayleigh and Lamb guided more. It was also applied to the characterization of shells using the radiation of circumferential guided modes. A review of the different solutions that have been proposed to improve this analysis will be given. Then, selected experimental examples of time reversal invariants will be discussed.
Evaluation of concrete carbonation using time reversal and nonlinear acoustics
Authors: Le Bas Pierre-yves , Payan Cedric , Ulrich Timothy J. , Garnier Vincent
Published: November 2013

Carbonation of concrete can lead to corrosion of rebar and degradation of structures, including nuclear plant walls and reactors and casks for storage of nuclear waste. Carbonation has been shown to decrease the natural nonlinearity of concrete. Using the time reversal nonlinear elastic diagnostic (TREND) at different frequencies allows for probing at different depths (half a wavelength). By looking at the evolution of the nonlinear response with frequency we can estimate the depth of carbonation. This study will present experimental results aimed at determining the depth of carbonation on medium scale samples (25×50×10 cm and 75×100×20 cm). The samples have been prepared using a protocol known to induce carbonation down to a controlled depth. Several samples are available with carbonation at 0, 1, 2, and 4 cm. We will present the results of the experiments analyzed using several techniques to quantify nonlinearity, namely, pulse inversion and Scaled Subtraction Method (SSM).
Applying an old appealing idea to modern seismology: Time reversal to characterize earthquakes
Authors: Larmat Carene , Guyer Robert A. , Johnson Paul A. , Montagner Jean-Paul
Published: November 2013

Wave physics is one domain where reversing time is possible and has led to interesting applications. In acoustics, Parvulescu and Clay (1965) used what they termed a “matched signal technique” to beat multi-reverberation in the shallow sea. In seismology, McMechan (1982) demonstrated the feasibility of what he termed “wavefield extrapolation” to locate seismic sources. Since then, other concepts and applications, all related to time-reversal, have often been proved to be successful where other techniques have failed. This success is due to the inherent ability of time-reversal to function well in complex propagation media as well as the remarkable robustness of the method with sparse receiver coverage. The key aspect of time-reversal for future applications in seismology is that it relies on no a priori assumption about the source. This allows automatic location of earthquakes and the study of seismic events for which the assumption of point source breaks down. This is the case of big earthquakes (Mw >8) for which the rupture length and source duration extend to hundreds of kilometers and several tens of seconds. We will show an application to the 2011 Japan earthquake, to icequakes related to glaciers motions in Greenland and to seismic tremor with no clear onset.
A high amplitude non-contact acoustic source: from a proof of concept to the understanding of the mechanisms involved
Authors: Remillieux Marcel C. , Anderson Brian E. , Ulrich Timothy J. , Le Bas Pierre-Yves
Published: November 2013

Recently, the preliminary design of a high-amplitude, non-contact acoustic source was proposed for nondestructive testing applications [Le Bas et al., J. Acoust. Soc. Am. 134, EL52 (2013)]. The design is based on the principle of time reversal, a process to focus energy at a point in space. In the present work, the main physical mechanisms involved in the operation of this device are examined numerically using the finite-element (FE) method. First, a three-dimensional FE model of the device is validated in the frequency domain against experimental data. Subsequently, two-dimensional transient simulations are used to conduct a parametric study on the effect of wall thickness and transducer density on the efficiency of the device. Last, a time reversal numerical experiment is presented. Results from this study can be used to design a more efficient non-contact source. [Work supported by Institutional Support (LDRD) at the Los Alamos National Laboratory.]
Statistics of internal waves measured during the Shallow Water 2006 experiment
Authors: Badiey Mohsen , Wan Lin , Lynch James F.
Published: November 2013

During the Shallow Water Acoustic Experiment 2006 (SW06), detailed measurements of the time-varying ocean environment were made while simultaneously acoustic signals were transmitted between various source and receiver pairs. The time-varying environment induced by internal waves (IW) was recorded by an array of moored thermistor chains, as well as by the attending research vessels. Using a mapping technique described by Badiey et al. [J. Acoust. Soc. Am. EL. 134 (2013)], the three-dimensional (3D) temperature field for over a month of IW events was reconstructed. The results of this mapping are used for the statistical analysis of the IW parameters, such as the IW propagation speed, direction, amplitude, coherence length, etc. This paper provides a summary of these results and also examines the implications of the detailed statistics as regards to the acoustic field. The results in this paper could be used as a database for studying the IW generation, propagation, and its impact on the 3D acoustic propagation in waveguides. [Work supported by ONR322OA.]
A perspective of modeling internal wave/acoustic wave interactions at the Naval Research Laboratory 1992-2012
Authors: Finette Steven I.
Published: November 2013

Interest in modeling internal gravity waves in littoral regions was stimulated by the discovery of anomalous transmission loss in the Yellow Sea, predicted by Zhou and Rogers in 1991 to be caused by solitary wave propagation along the acoustic transmission path. Over the past 20 years, we have been modeling acoustic wave/solitary internal wave interactions and an overview and perspective of some of this work, illustrated by examples, will be presented. The relationship between internal waves and the scintillation index, horizontal refraction of acoustic energy, oceanographic waveguide focusing, mode coupling between acoustic and internal wave modes, and the effect of internal waves on acoustic field uncertainty are discussed. Some thoughts on the future of 4-D simulation of acoustic/internal wave interactions and modeling in the context of incomplete environmental knowledge are considered. [Work supported by the Office of Naval Research.]
Simple expressions for the horizontal array coherence length in shallow water acoustics
Authors: Lynch James , Newhall Arthur , Duda Timothy , Siegmann William , Colosi John
Published: November 2013

The use of simplified “feature models” (geometric idealizations of specific, isolated ocean features) for coastal oceanographic features can allow one to calculate acoustically useful quantities approximately and even generate analytic forms for them. Feature models for coastal fronts, eddies, internal tides, linear and nonlinear internal waves, and spice are presented and the scattering of sound from these objects is calculated. This allows one to estimate the useful quantity Lcoh, the horizontal coherence length that represents a physical limit for array signal processing. Calculations of Lcoh and their comparisons with data will be presented. The effects of acoustic multipath propagation, which can compete with the medium scattering in the estimates of Lcoh, are also estimated using basic models. [Work sponsored by the Office of Naval Research.]
Time reversal of modal arrivals for broadband signals in horizontally stratified shallow water due to internal waves
Authors: Badiey Mohsen , Luo Jing
Published: November 2013

Shallow water waveguides in the presence of internal waves can make a time-varying, horizontally stratified medium that can significantly affect broadband pulse propagation. In this paper, we analyze a unique data set obtained during the passage of an internal wave event in a region where a broadband sound source (270 to 330 Hz) was received by an L-shaped hydrophone array about 20 km away in 80 meters on the New Jersey continental shelf. During the time 20:30 and 22:07 GMT, on 17 August 2006, an approaching IW affected the dispersion characteristic of the broadband LFM chirp signal while passing an acoustic track in shallow water waveguide. Modal behavior is examined before and after the internal wave front crossed the source-receiver track. While dispersion characteristics of the signals changed, modal arrival time reversal occurred. The corresponding group and phase velocities that signals experienced during this phenomenon are analyzed using the theory of horizontal rays and vertical modes. These results have motivated theoretical and modeling studies of the waveguide behavior since it was first reported in 2010. [Work supported by ONR322OA.]
Value based education for healthcare design
Authors: Logsdon Edward
Published: November 2013

Accelerating the understanding and adoption of the FGI Guidelines is an essential part of the continuous improvement process—especially at a time when healthcare is coping with so much rapid change, and while the FGI Guidelines are becoming more accepted internationally. As part of the process to improve the acoustical environment in healthcare facilities, there is also the continual need to educate architects and designers concerning sound and vibration design criteria included in the FGI Guidelines. Designers need to understand how to apply the criteria, proposed changes to the guidelines, and how the changes will benefit the hospital by improving the patient experience. Using professional social networking, electronic, and face-to-face continuing education combined with research based design, professionals and the public can be educated on the merits of improvement in the acoustical design of healthcare facilities. Web-based education will attract a much wider audience worldwide and further international acceptance. Project case studies where FGI Guidelines were applied will identify the cost impact while increasing awareness and understanding.
Top ten research needs in the decade ahead
Authors: Sykes David M. , Cavanaugh William J.
Published: November 2013

Independent, third-party research co-led by teams including medical personnel, engineers, and scientists is key to raising the bar on acoustical performance in healthcare facilities. While links between noise and health have been officially ignored in the United States for three decades, research over the past eight years in healthcare environments has significantly advanced understanding and created a small community of funding organizations and interested researchers. To make further progress, researchers must demonstrate clear links between noise/sound and patient outcomes as well as the performance effectiveness of healthcare professionals on critical factors such as error rates. Achieving useful, translational results requires: innovative research methods, collaborative funding mechanisms, and a clear focus on outcomes. With no Federal agency providing organized peer-review, it is essential for the acoustics research community to both agree on a research agenda and organize peer-review procedures that will enable continued progress among a widely distributed population of researchers working within the constraints of limited funding. The presenter worked with FGI to draft a “top 10” research agenda. He co-chairs the FGI Acoustics Working Group, edits the Springer Verlag “Quiet series,” and has experimented with collaborative research funding mechanisms over the past three decades.
Why alarm fatigue is a pivotal issue that affects the acoustical design of healthcare facilities
Authors: Barach MD Paul
Published: November 2013

The U.S. FDA and Joint Commission designated “alarm fatigue” the “#1 priority in healthcare technology” in 2011–2012, acknowledging that this acoustical problem results in hundreds of patient deaths and thousands of injuries. The healthcare facilities industry has been slow to recognize that “alarm fatigue” is partly a facility design issue: i.e., a cacophony of recurrent noises from myriad uncorrelated medical devices, set at maximum loudness, occurring in hard-walled, reverberant spaces (such as patient rooms, ORs, and ICUs) produce elevated stress, sleep impairment, disorientation, and dangerously irrational, potentially deadly behavior. “Alarm fatigue” has been addressed as a human factors problem elsewhere: e.g., nuclear plant control rooms (after Three-Mile Island) and aircraft cockpits. In healthcare, it is imperative to engage architects, designers, acoustical engineers facility engineering staffs, and clinicians, who represent the “first line of defense” as the medical device industry requires 5–10 years to implement solutions. The presenter co-led a delegation of 12 distinguished members of the acoustics profession to the national summit on “alarm fatigue,” Washington DC, 2011 and has co-authored peer-reviewed medical journal articles and a forthcoming FGI white paper on the subject. This presentation focuses on solutions, challenges, and the research roadmap needed to address “alarm fatigue.”
Estimation of noise induced hearing loss because of indoor and outdoor environment noise factors in Turkish healthcare facilities: A survey of hospitals in Turkey
Authors: Kocyigit Filiz
Published: November 2013

This article aims to evaluate effect of indoor and outdoor environment noise factors in healthcare facilities which affect the work area due to noise induced hearing loss, and also to determine their relationship with the architectural design of the building. As a case study; noise levels, in five state and private healthcare centers, including medical schools, research hospitals, and state hospitals in Turkey were measured. They were compared with similar healthcare centers in the United States. Results include equivalent sound pressure levels (Leq for 5 min from 20 spots in each area), and Lmax–Lmin evaluated as a function of location, frequency, time, and days of the week. Research showed that no location was in compliance with current World Health Organization Guidelines, and a review of objective data indicated that this was true of hospitals throughout the world. Noise induced hearing loss on continuously users had been estimated with these results in selected hospitals. Data gathered at various hospitals for last decay indicate a trend of increasing noise levels during daytime and nighttime hours. The implications of these results were significant for patients, visitors, and hospital staff.
Controlled sound exposure experiments to measure marine mammal reactions to sound: Southern California behavioral response study
Authors: Southall Brandon L. , Calambokidis John , David Moretti , Barlow Jay , DeRuiter Stacy , Goldbogen Jeremy , Friedlaender Ari , Hazen Elliott , Stimpert Alison , Patricia Arranz , Falcone Erin , Schorr Greg , Douglass Annie , Kyburg Chris , Tyack Peter
Published: November 2013

SOCAL-BRS is an inter-disciplinary collaboration designed to increase understanding of marine mammal behavior and provide a robust scientific basis for estimating risk and minimizing effects of mid-frequency military sonar systems. Data were collected using visual observations, passive acoustic monitoring, animal-attached acoustic and movement tags, photo ID, biopsy, and controlled sound exposure experiments on over 20 cetacean species in biologically important areas throughout the southern California Bight. Ninety-six individuals of ten species were tagged with six tag types, including two species [Baird’s beaked whale (Berardius bairdii), Risso’s dolphin (Grampus griseus)] not previously studied with such tools. Fifty-six controlled CEEs were conducted using protocols and protective measures to ensure animals were not harmed. Simulated sonar signals were projected through a deployed sound source and changes in vocal, diving, and horizontal movement behavior were measured. Results demonstrate that Cuvier’s beaked whales (Ziphius cavirostris) react most strongly to simulated sonar exposures with clear changes in vocal and diving behavior and avoidance responses at low received sound levels. Blue whale (Balaenoptera musculus) responses are more variable, depending on complex interactions of exposure and behavioral conditions. Ongoing efforts include expanding sample sizes in other species using simulated sounds and the novel inclusion of operational mid-frequency sonars.
The next generation of multi-sensor acoustic tags: Sensors, applications, and attachments
Authors: Nowacek Douglas , Bowers Matthew , Cannon Andrew , Hindell Mark , Howle Laurens E. , Murray Mark M. , Rittschof Dan , Shorter K. Alex , Moore Michael
Published: November 2013

From Kooyman’s 1963 wind-up kitchen timer TDR, multi-sensor tags have evolved significantly over the last twenty years. These advancements, including high fidelity acoustics, have been driven by improved sensing and electronics technology, and resulted in highly integrated mechatronics systems for the study of free ranging animals. In the next decade, these tags will continue to improve, and promising work has begun in three key areas: (i) new sensors; (ii) expanding uses of existing sensors; and (iii) increasing attachment duration and reliability. The addition of rapid acquisition GPS and the inclusion of gyroscopes to separate the dynamic acceleration of the animal from gravitational acceleration, are underway but not widely available to the community. Existing sensors could be used for more and different applications, e.g., measuring ambient ocean noise. Tags attached to pinnipeds in the Southern Ocean, for example, could provide noise measurements from remote areas. Finally, attachment duration has been limiting for cetaceans because the suction cups typically used do not reliably stay attached for more than a day. We will present data on engineering efforts to improve attachments: (i) improved tag hydrodynamics; (ii) incorporating bio-compatible glues; and (iii) micro structuring tag components to utilize hydrostatic forces and enhance adhesion.
The relationship between vessel traffic and noise levels received by killer whales
Authors: Houghton Juliana , Holt Marla , Giles Deborah , Emmons Candice , Hanson Brad , Hogan Jeff , Branch Trevor , VanBlaricom Glenn
Published: November 2013

Cetaceans that rely on their acoustic environment for key life history strategies are susceptible to noise effects from anthropogenic use such as ecotourism. Endangered Southern Resident killer whales (SRKW) are the primary target for vessel-based whale-watching in the Salish Sea. Vessel interactions and associated noise have been identified as potential stressors for SRKW. Previous research has indicated that both stressors negatively impact SRKW; however, there is a missing link between vessel characteristics/behavior and noise levels actually received by individual whales. To investigate this relationship, data were collected concurrently using mobile remote sensing survey equipment packages and digital acoustic recording tags. This allowed us to obtain precise geo-referenced vessel data and noise levels received by the whales. We used linear regression to summarize patterns in vessel characteristics and relate them to received noise levels. Received noise levels (RNL) were correlated with the number of vessels. RNL also increased when larger vessels were present or when vessels were traveling at relatively high speed. These findings facilitate improved understanding of the contributions of vessel characteristics to the noise levels received by individual cetaceans. Results from this study can be used to refine existing vessel regulations in order to better manage SRKW to recovery.
Use of Automated passive acoustic monitoring methods for monitoring for marine mammals in conjunction with US Navy Mid-frequency Active Sonar training events
Authors: Martin Stephen W. , Manzano-Roth Roanne A. , Matsuyama Brian M.
Published: November 2013

Automated passive acoustic detection, classification, and localization (DCL) methods are employed to deal with large volumes of acoustic data to support estimating the sound pressure levels (SPLs) that marine mammals are exposed to from mid-frequency active sonar (MFAS) during US Naval training events. These methods are applied to a training event involving MFAS conducted February 2012 in Hawaiian waters with thirty one hydrophones of data collected continuously over an 11 day period. The automated methods detect and determine locations of marine mammals, specifically minke and beaked whales, and the times of the MFAS transmissions utilizing custom C + + algorithms. Streamlined manual validation methods are employed which utilize custom Matlab display routines. Animal locations uncertainties are addressed for the two different species. Once the transmitting ship and animal locations are determined acoustic propagation modeling is utilized to estimate the sound pressure levels (in dB re 1 micro Pascal) that an animal, or group of animals, were exposed to. Surface ducted propagation conditions can result in species such as beaked whales being exposed to over 30 dB higher SPL’s when they return to the surface to breathe compared to when at depth foraging.
Vocalization behaviors of minke whales in relation to sonar in the planned Undersea Warfare Training Range off Jacksonville, Florida
Authors: Dominello Talia , Norris Thomas , Yack Tina , Ferguson Elizabeth , Hom-Weaver Cory , Kumar Anurag , Nissen Jene , Bell Joel
Published: November 2013

Nine Marine Autonomous Recording Units (MARU’s) were deployed in a rectangular array at a site coinciding with the United States (U.S.) Navy’s planned Undersea Warfare Training Range (USWTR) approximately 60–150 km offshore Jacksonville, FL (13 September to 8 October and 3 December to 8 January, 2009–2010) at shallow, mid-depth, and deep sites (45, 183, 305 m). Data were reviewed in detail using Triton (Wiggins, 2007). Event logs were created for each day at every site. Custom-written MATLAB scripts were used to calculate the probability of minke whale vocalization events occurring in the presence and in the absence of mid-frequency sonar. Minke whale vocalization events were completely absent in the fall deployment period, but occurred almost continuously during the winter deployment, indicating a strong seasonal pattern of occurrence. Minke whale vocalizations were detected most frequently at deep-water sites, and only at low levels (<0.03% of time) at shallow-water sites. Results of the probability analysis indicated a strong negative correlation to sonar. Minke whale vocalization events were greatly reduced, or completely ceased, during most days with nearly continuous sonar events during an approximate 3-day period. To our knowledge, such changes in acoustic behaviors of minke whales in relation to sonar have not been reported before.
The characteristics of boat noise in marine mammal habitats
Authors: Erbe Christine
Published: November 2013

Environmental management of underwater noise tends to focus on sources related to offshore oil and gas exploration and navy operations. However, in many, specifically near-shore habitats, boat noise prevails, yet remains largely unregulated. Underwater noise of personal watercraft (jet skis) was recorded in Queensland, and consisted of broadband energy between 100 Hz and 10 kHz attributed to the vibrating bubble cloud generated by the jet stream, overlain with frequency-modulated tonals corresponding to impeller blade rates and harmonics. Broadband monopole source levels were 149, 137, and 122dB re 1 μPa @ 1m (5th, 50th, and 95th percentiles). Underwater noise of zodiacs (inflatable boats with outboard motors) operated by whale-watching companies was recorded in southern British Columbia. At slow cruising speeds (10 km/h), underwater noise peaked between 50 and 300 Hz; at fast traveling speeds (55 km/h), underwater noise peaked between 100 and 3000 Hz, exhibiting strong propeller blade rate tonals at all speeds. Broadband source levels increased with speed from 126 to 170dB re 1 μPa @ 1m according to SL = 107 + 32 log10(speed/km/h). Even though noise levels from jetskis are lower than those of propeller-driven boats, it is not necessarily the broadband source level that correlates with the bioacoustic impact on marine fauna.
Low boiling point perfluorocarbon nanodroplets for biomedical imaging and therapeutics
Authors: Sheeran Paul S. , Matsunaga Terry O. , Dayton Paul A.
Published: November 2013

Perfluorocarbon (PFC) droplets have been examined for biomedical applications for more than a decade. Of particular interest are “phase change” PFC droplets, which can convert from liquid to gaseous phase with an acoustic energy input. In liquid form, these droplets demonstrate stability not capable with microbubbles, but in gaseous form the resultant bubble provides the cavitation source that is crucial for ultrasound imaging or therapeutic mediation. Traditionally, phase-change droplets have utilized PFCs with boiling points close to body temperature, so that they could be readily activated with acoustic energy input. However, the desire reduce these droplets to hundred-nanometer sizes in order to reach the extravascular space has made PFC selection more complicated. Specifically, the influence of surface tension on droplets that are significantly smaller than a micron elevates the boiling point past that of the bulk fluid, making hundred-nanometer sized droplets challengingly difficult to vaporize with diagnostic ultrasound energy levels. Our solution has been a unique approach to condense low boiling point gaseous perfluorocarbons, creating a population of meta-stable PFC nanodroplets. The resulting nanodroplets exhibit stability, yet have very low energy activation requirements. We discuss advantages and disadvantages of this new formulation, and demonstrate applications in biomedical imaging and therapeutics.
Entropy imaging and nanostructures
Authors: Hughes Michael , McCarthy John E. , Marsh Jon N. , Wickline Samuel A.
Published: November 2013

Virtually all imaging devices today function by collecting either electromagnetic or acoustic waves and using the energy carried by these waves to determine pixel values to build up what is basically an “energy” picture. However, waves also carry information and this can also be used to determine the pixel values in an image. We have employed several measures of information all of which are based on different forms of entropy. Numerous published studies have demonstrated the advantages of entropy, or “information,” imaging over conventional methods in materials characterization and medical imaging. Moreover, the technique is robust as these results were obtained using a variety of imaging systems having different frequency ranges and transducers. Similar results have also been obtained using microwaves. We will present the results of several entropy-imaging-based in vivo studies. The first of these were based on a non-gaseous liquid-filled nanoparticle contrast agent used to image tumors. We will also present a study of therapy monitoring of muscular dystrophy conducted without contrast. In both studies entropy images were able to detect changes in backscattered ultrasonic signals that were not detectable using conventional techniques.
Characterization of liquid-filled nanoparticles for detection and drug-delivery in tumors
Authors: Taulier Nicolas , Payen Thomas , Jafari Sara , Mamou Jonathan , Elias Fattal , Tsapis Nicolas , Bridal Lori
Published: November 2013

Liquid-filled nanoparticles provide long half-life circulation favoring accumulation in the interstitial space of tumors through enhanced permeation and retention. However, these relatively incompressible nanoparticles are much less echogenic than those with a gas-core. We have worked to characterize and optimize the acoustic response of PLGA-shelled, perfluorooctyl bromide (PFOB) core nanoparticles (radii 70 to 200 nm ; shell-thickness-to-radius ratio 0.25 to 1). Acoustic response (attenuation coefficient, ultrasonic velocity, and relative backscattered intensity) was explored in vitro for ranges of concentration, shell-thickness, acoustic pressures and pulse durations (20 to 40 MHz). Modification of the surface chemistry of the polymeric shell with fluorescent, pegylated, or/and biotinylated phospholipids was not associated with apparent response modification. Successful incorporation of paclitaxel in the shell has been achieved but currently the thick-shells of these nanoparticles impede ultrasound-triggered delivery. Although work remains to better adapt liquid-filled nanoparticles for detection and delivery, trials demonstrating nanoparticle detection in vivo in mice indicate their potential for accumulation, and detection in tumors.
Subwavelength droplets in nonlinear ultrasound fields: Simulation of focusing effects
Authors: Verweij Martin D. , Sphak Oleksandr , Vos Hendrik J. , de Jong Nico , Lohse Detlef , Versluis Michel
Published: November 2013

Ultrasound can trigger the evaporation of tiny droplets of emulsified, superheated fluids like perfluorocarbon. This acoustic droplet vaporization (ADV) effect is important because of its potential medical applications. For example, drug-loaded nanodroplets can penetrate the vessel wall and subsequently release their therapeutic load through acoustic activation. Until now, the medical application of ADV has been limited by lack of understanding of the acoustic activation mechanism. In an accompanying paper, a mechanism is proposed that can fully explain the experimentally observed phenomena such as a frequency dependent pressure threshold. The mechanism involves focusing of higher harmonics of the nonlinear activation field. In the current presentation it will be explained how the focusing effect is simulated. A particular problem here is that typical droplet sizes are in the order of micrometers, while typical wavelength sizes are in the order of hundreds of micrometers. This difference in scale will render the traditional analytic solution numerically useless. The problem is avoided by using appropriate expansions of the functions involved. Numerical results are presented that show a focusing effect inside the droplet for a range of incident harmonics. These results have enabled the demonstration of the mechanism in the accompanying paper.
Dual perfluorocarbon nanodroplets enhance high intensity focused ultrasound heating and extend therapeutic window in vivo
Authors: Phillips Linsey C. , Sheeran Paul S. , Puett Connor , Timbie Kelsie F. , Price Richard J. , Miller G. Wilson , Dayton Paul A.
Published: November 2013

Perfluorocarbon microbubbles are known to enhance high intensity focused ultrasound (HIFU) ablation by cavitation. However, they can result in superficial skin heating, minimizing their clinical translation. Perfluorocarbon nanodroplets activate only at the higher pressures present at the acoustic focus. We hypothesized that a mixed perfluorocarbon nanodroplet formulation would minimize surface heating while still enhancing ablation. Tissue-mimicking phantoms containing microbubbles or nanodroplets were sonicated (1 MHz, 15 W, 60 s) to assess heating and lesion formation in vitro. Microbubbles or nanodroplets were injected into rats (n = 3) and HIFU (1 MHz, 15 W, 15 s) was focused into each liver while under MRI guidance. Temperature throughout the liver was tracked by MR thermometry. In vitro, microbubbles caused excess surface heating during HIFU, whereas nanodroplets did not. In vivo, microbubbles typically circulate for less than 15 min. In comparison, the nanodroplets remained viable in circulation for at least 96 min. HIFU lesions of consistent volume were produced during this time and reached the same maximal temperature rise (Δ550 °C). In the absence of nanodroplets or microbubbles, significantly greater power (25 W) and twice as much time (30 s) was required to generate an ablation lesion in the liver. These results demonstrate the ability of nanodroplets to more safely shorten ablation procedures.
Use of micro- and nano-sized inertial cavitation nuclei to trigger and map drug release from cavitation-sensitive liposomes
Authors: Graham Susan M. , Myers Rachel S. , Choi James , Bazan-Peregrino Miriam , Seymour Leonard , Carlisle Robert , Coussios Constantin C.
Published: November 2013

Encapsulation of cytotoxic drugs into liposomes enhances pharmacokinetics and improves passive accumulation in tumors. However, stable liposomes have limited drug release, and thus action, at the target site. This inefficient and unpredictable drug release is compounded by a lack of low-cost, non-invasive methods to map release in real time. We present a new liposomal vehicle that is exclusively triggered by inertial cavitation. Ultrasound exposure of these liposomes in the absence of SonoVue® provided no increase in drug release, whilst with SonoVue® at inertial cavitation pressure levels a substantial (30%) and significant (p < 0.001) increase was observed in vitro. A 16-fold increase in the level of drug release within tumors was similarly observed in the presence of inertial cavitation following intravenous delivery. Passive acoustic mapping of inertial cavitation sources during delivery was also found to correlate strongly with the presence of release. However, variability in tumor perfusion indicated that uneven distribution of micron-sized SonoVue® may limit this approach. Nano-scale cavitation nuclei, which may more readily co-localize with 140 nm liposomes, were thus developed and showed similar cavitation energies to SonoVue® in vitro. These nano-nuclei may ultimately provide a more reliable and uniform way to trigger drug release in vivo.