bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic and perceptual similarities between Effutu and English fricatives: Implications for English as a second language
Authors: Lomotey Charlotte F.
Published: September 2012

Volin & Skarnitzl (2010) describe a foreign accent as a set of pronunciation patterns, at both segmental and suprasegmental levels, which differ from pronunciation patterns found in the speech of native speakers (p.1010). Not only can these pronunciation patterns differ, they can also be similar in many ways. These similarities can be perceptual, acoustic and auditory, especially at the segmental level. This study investigates the acoustic and perceptual similarities between the fricatives /s/, /f/ and /∫/ of Effutu, a dialect of Awutu, and their English counterparts in the context of /a/ and /i/. Duration and spectral peak frequency are measured in order to achieve this. A discrimination task, Same-Different task, was administered to investigate listeners’ perceived similarity (or difference) judgments between the pairs of fricatives. Preliminary findings show that there are perceptual and acoustic differences in the durations of these segments cross-linguistically. This study contributes to cross-linguistic investigation of fricatives, and to second language acquisition. The findings also show that the use of acoustic and perceptual cues helps to establish differences between speech sounds in different languages, and that, ESL teachers can use these to develop appropriate ways of teaching English sounds to learners.
Phonetic accommodation after passive exposure to native and nonnative speech
Authors: Kim Midam , Bradlow Ann R.
Published: September 2012

We investigated native English talkers’ phonetic accommodation to a native or nonnative model talker in a passive auditory exposure setting. We performed a phonetic accommodation experiment, following the procedure of Goldinger & Azuma (2004). Specifically, the imitators read monosyllabic words, disyllabic words, and sentences before and after perceptual exposure to the stimuli. We found evidence of phonetic convergence both to native and nonnative model talkers from various acoustic measurements on words and sentences, and dynamic time warping analyses and XAB perception tests on sentences. We also found that dialect mismatch between participants and native model talkers inhibited phonetic convergence in some acoustic measurements. Additionally, the distances between model talkers and participants along the acoustic measurements before auditory exposure positively affected their degrees of phonetic convergence, regardless of the direction of the change; the farther the acoustic distance was before the auditory exposure, the larger the degree of phonetic convergence was. Moreover, the imitators generalized their accommodation patterns from exposed to unexposed items. Finally, XAB perception tests with the sentences revealed that imitators of all model talkers were perceived as converging towards their model talker, and importantly, this pattern of perceived accommodation was predicted by most of the sentence-based acoustic measurements.
Delayed use of fundamental frequency (F0) rise in non-native speech segmentation
Authors: Coughlin Caitlin E. , Tremblay Annie
Published: September 2012

Research has shown that second/foreign language (L2) speech segmentation is less efficient than native language (L1) segmentation, because L2 learners cannot suppress L1 segmentation routines. This study uses visual-world eye-tracking to determine whether English learners of French can learn to use F0 for locating word-final boundaries in French. F0 rise is often word-initial in English but often word-final in French. Native French speakers and English learners of French heard sentences where lexical competitors were created between the target noun and the following adjective (stimulus: chat grincheux ‘cranky cat’; target: chat ‘cat’; competitor: chagrin ‘sorrow’). The target was either accented or unaccented, and the stimuli were either natural or resynthesized (swapped F0 between accented and unaccented targets). Participants selected the word they heard from given options (target, competitor, distracters), and fixations were recorded from target-word onset. Accuracy (word selection): learners, but not natives, were more accurate for target words with F0 rise than without it. Fixations: natives, but not learners, showed higher differential proportions of target and competitor fixations for target words with F0 rise than without it. Proficiency did not interact with the variables. This suggests that L2 learners’ use of F0 rise is delayed compared to that of natives.
Cross-language assimilation of lexical tone
Authors: Alexander Jennifer , Wang Yue
Published: September 2012

We extend to lexical-tone systems a model of second-language perception, the Perceptual Assimilation Model (PAM) (Best & Tyler, 2007), to examine whether/how native-language lexical-tone inventory composition influences perception of novel tone. Native listeners of Cantonese, Thai, and Mandarin perform a tone mapping-rating assimilation task. Listeners hear CV syllables bearing all tones of Cantonese, Thai, Mandarin, and Yoruba - languages with different tone inventories. They (1) map the tone they hear to the nearest native tone category, and (2) provide a goodness rating on a 5-point scale (5 = perfect). As predicted by the PAM, listeners assimilated non-native tones to the phonetically-closest native tone categories. Listeners attended primarily to pitch-contour, and secondarily to pitch-height, contrasts for the mappings. E.g., Mandarin listeners assimilated the Thai high “level” (phonetically mid-to-high-rising) tone to Mandarin rising tone 76% of the time, and to Mandarin high-level tone only 22% of the time. Also as predicted, all novel tones did not assimilate equally well to native categories; mappings received ratings between 2.9-4.1, averaging 3.5. The groups’ different patterns of results indicate that novel-tone perception is influenced by experience with the native-language tone inventory, and that listeners attend to gradient phonetic detail to assimilate novel tones to native-tone categories. This work is supported by NSF grant 0965227 to J.A.
Tonal adaptation of English loanwords in Mandarin: The role of perception and factors of characters
Authors: Mar Li-Ya , Park Hanyong
Published: September 2012

The present study investigates the role of orthography and perceptual similarity between the English stress and the Mandarin tone during the borrowing process of English words among Taiwanese Mandarin speakers. We had 7 Mandarin speakers transliterate 40 unfamiliar disyllabic US city names using Chinese characters. Based on the results, we created 28 stimuli consisting of possible Chinese borrowings and the target English word for AXB identification tasks. Then, we had the subjects choose the more similar Chinese form to an English target word after the auditory presentation of the stimuli, first without and second with written representations of the stimuli on different days. The transliteration results indicate that a stressed syllable is usually adapted with tones with a high pitch. The AXB task results show a character frequency and a semantics override perceptual similarity; when the adapted forms include characters used infrequently or with negative meanings, another form is chosen despite the fact that it is not the most perceptually similar form. The findings suggest that perceptual similarity mapping takes place first and other factors, such as semantics or the character frequency, come into play when the output contains an infrequently-used or semantically-negative character in tonal adaptation.
A physical statistical clutter model for active sonar scenarios with variable signal-to-noise ratios
Authors: Gauss Roger C. , Fialkowski Joseph M.
Published: September 2012

Active sonar classification algorithms need to be robust in preventing operator overload while not being misled by false targets. This talk describes a new 3-parameter statistical sonar clutter model that not only provides a physical context for relating the characteristics of normalized matched-filter echo-data distributions to scatterer attributes, but scatterer information that is largely independent of its peak signal-to-noise ratio (SNR) value. It extends our 2-parameter Poisson-Rayleigh model (Fialkowski and Gauss, IEEE JOE, 2010) by adding a quantitative measure of scatterer spatial dispersion to its measures of scatterer density and relative strength. Maximum likelihood estimates of the clutter model’s 3 parameters were derived from mid-frequency (1-5 kHz) shallow-water active sonar data containing returns from biologic, geologic and anthropogenic objects with differing spatial and scattering characteristics. The resulting clutter model’s probability density functions not only fit the non-Rayleigh data well while displaying an insensitivity to SNR, but the dispersion parameter values were consistent with the known spatial characteristics of the scatterers and the values’ ping-to-ping variance correlated strongly with clutter object class, all of which are encouraging with regard to developing robust physics-based active classification algorithms. [Work supported by ONR.]
Least squares channel estimation and adaptive equalization at low signal to noise ratios
Authors: Preisig James C.
Published: September 2012

Least squares based adaptive algorithms are among the most commonly used techniques for both channel estimation and adaptive equalization using signals that have propagated through underwater acoustic channels. Such channels are often characterized by long delay spreads meaning that the impulse response of the channel contains many “taps” or “weights” to be estimated or accommodated. In addition, the channel is often time varying which limits the duration of the averaging window that can be used by the algorithm’s adaptation process. At low SNRs, these two factors pose a significant challenge to algorithm performance. This challenge is particularly severe in the context of adaptive equalization where the use of multichannel equalizers is often required to achieve reliable performance and the traditional approach of joint optimization of the feedforward filter tap weights on all receiver channels results in large dimensional optimization problems. This talk will contrast and compare the impact of low SNR on least squares based channel estimation and adaptive equalization algorithms. The role of dimensionality reduction will be examined and the response of multichannel equalizers to different signal and noise environments as well under different equalizer configurations will be examined.
Nonlinear acoustic pulse propagation in range-dependent underwater environments
Authors: Maestas Joseph T. , Collis Jon M.
Published: September 2012

The nonlinear progressive wave equation (NPE) is a time-domain formulation of Euler’s fluid equations designed to model low angle wave propagation using a wave-following computational domain [B. E. McDonald et al., JASA 81]. The wave-following frame of reference permits the simulation of long-range propagation that is useful in modeling the effects of blast waves in the ocean waveguide. The standard formulation consists of four separate mathematical quantities that physically represent refraction, nonlinear steepening, radial spreading, and diffraction. The latter two of these effects are linear whereas the steepening and refraction are nonlinear. This formulation recasts pressure, density, and velocity into a single variable, a dimensionless pressure perturbation, which allows for greater efficiency in calculations. Nonlinear effects such as weak shock formation are accurately captured with the NPE. The numerical implementation is a combination of two numerical schemes: a finite-difference Crank-Nicholson algorithm for the linear terms of the NPE and a flux-corrected transport algorithm for the nonlinear terms. While robust, solutions are not available for sloping seafloors. In this work, range-dependent environments, characterized by sloping bathymetry, are investigated and benchmarked using a rotated coordinate system approach.
Transport theory applied to shallow water acoustics: The relative importance of surface scattering and linear internal waves
Authors: Raghukumar Kaustubha , Colosi John A.
Published: September 2012

Acoustic fields in shallow water have a statistical nature due to complex, time-evolving sound speed fields and scattering from rough boundaries. A coupled-mode transport theory [Creamer (1996), Colosi and Morozov (2009)] allows for the prediction of acoustic field second moments like mean intensity and coherence. This was previously applied to study low frequency acoustic fluctuations in an environment typical of that of the Shallow Water 2006 (SW06) experiment on the New Jersey Continental shelf. Here the propagation was found to be strongly adiabatic and random sound speed fluctuations from internal waves radically altered acoustic interactions with intense nonlinear internal wave packets. Here, we extend the SW06 study to examine the ability of transport equations to describe high frequency (>1 kHz) sound in shallow water. Mode coupling rates from internal waves are expected to be larger, and scattering effects from rough surfaces need treatment. The aforementioned transport theory is merged with the rough surface scattering transport theory of Thorsos et al (2009). Oceanographic and sea surface measurements are used to constrain the internal wave and sea surface models. The relative importance of linear internal waves and surface scattering effects are studied using transport theory and Monte Carlo simulations.
Range dependent acoustic intensity scintillations due to focusing, defocusing, and scattering by sea swell and bottom sediment waves
Authors: Shmelev Alexey A. , Lynch James F. , Lin Ying-Tsong , Newhall Arthur E. , Duda Timothy F.
Published: September 2012

It is known that the waveguide depth variability causes horizontal refraction and coupling of acoustic normal modes. Presence of large bottom sediment waves and sea swell are examples of strongly anisotropic waveguides that result in range dependence of the acoustic scintillation index. In the directions parallel to the wave crests, three-dimensional effects of mutual horizontal focusing, defocusing and diffusion between such waves are the main mechanisms of intensity fluctuations. For acoustic propagation in the perpendicular to the wave crests directions, intensity fluctuations are mainly driven by random mode coupling and scattering. Analytical studies and numerical examples of the acoustic scintillation index, as well as its azimuthal and range dependence in the shallow water with both types of waves, will be provided. Directions for future studies will be discussed.
Deep seafloor arrivals in long range ocean acoustic propagation
Authors: Stephen Ralph A. , Bolmer S. Thompson , Dzieciuch Matthew A. , Worcester Peter F. , Andrew Rex K. , Mercer James A. , Colosi John A. , Howe Bruce M.
Published: September 2012

Ocean bottom seismometer observations during the long-range ocean acoustic propagation experiment in the North Pacific in 2004 showed robust, coherent, late arrivals that were not observed on hydrophones suspended 750m and more above the seafloor and that were not readily explained by ocean acoustic propagation models. The DSFA arrival pattern on the OBSs near 5000m depth are a delayed replica, by about two seconds, of the arrival pattern on the deepest element of the DVLA at 4250m depth (DVLA-4250). Using a conversion factor from the seafloor vertical particle velocity to seafloor acoustic pressure, we have quantitatively compared signal and noise levels at the OBSs and DVLA-4250. Ambient noise and DSFA signal levels at the OBSs are so quiet that if the DSFA arrivals were propagating through the water column, perhaps on an out-of-plane bottom-diffracted-surface-reflected (BDSR) path, they would not appear on single, unprocessed DVLA channels. Nonetheless arrival time and horizontal phase velocity analysis rules out BDSR paths as a mechanism for DSFAs. Whatever the mechanism, the measured DSFAs demonstrate that acoustic signals and noise from distant sources can appear with significant strength on the seafloor at depths well below the conjugate depth.
Effects of fine-scale topographical change on mid-frequency bottom loss
Authors: Yang Jie , Tang Dajun
Published: September 2012

It was shown previously [Yang et al, J. Acoust. Soc. Am. 131(2), 1711-1721 (2012)] that forward scatter from topographical changes could alter bottom loss at mid-frequencies. In this more detailed study, fine-scale bottom bathymetry data from a multibeam survey are used as inputs to numerical experiments to investigate the effects of topographical variation on bottom loss (BL). Bottom reflection/forward scatter simulations in the frequency band of 2--5 kHz are carried out using several numerical methods which all include the effect of bathymetry variation. Bottom bounces including forward scatter are treated as if the bottom is flat and are used to estimate BL at different frequencies. It is found that small topographic changes can result in large deviations in BL estimates. Remedies for the effect of bottom topography change on BL are suggested. [Work supported by ONR.]
Modeling the effect of interface roughness on bottom loss from layered interfaces with finite elements
Authors: Isakson Marcia J. , Chotiros Nicholas P.
Published: September 2012

The bottom loss from a layered ocean sediment is determined using a finite element/boundary element (FE/BE) method. First, the pressure and its normal derivative are calculated on the top interface using finite elements. Then the field at a point outside of the domain is determined using the Helmholtz/Kirchhoff integral (BE). Bottom loss is then calculated by comparing the reflected/scattered energy to the incident energy. The finite element method makes no approximations to the Helmholtz equation and is exact within the limits of the discretization. Any number of layers including elastic layers with rough or smooth interfaces can be included. The results of the FE/BE approach will be compared to Geoacoustic Bottom Interaction Model (GABIM) for a number of test cases. [Jackson, et al., IEEE J. Ocean. Eng. 35(3), 603-617 (2010)] GABIM computes the layered reflection coefficient then includes scattering for one rough interface based on “a combination of the Kirchhoff approximation, first-order perturbation theory and an empirical expression for very rough seafloors”. Lastly, the bottom loss of multiple rough interfaces will be compared to that of a single rough interface. [Work supported by ONR, Ocean Acoustics.]
Jurassic acoustics: Low frequency sound absorption in the ocean during past ages
Authors: Browning David , Scheifele Peter M.
Published: September 2012

A major aspect of global warming is ocean acidification. To provide a baseline for future change, investigators have been able to track the geological record of ocean acidification back to 300 million years ago (mya). One of the key factors is tracing the history of boron isotopes. The principal low frequency sound absorption mechanism in seawater is a boron reaction which is pH dependent (the lower the pH, the lower the absorption), so this geological record can be used to estimate sound absorption in the ocean all the way back to the carboniferus period. The broad picture is that low frequency absorption in the ocean decreased from 300 mya to 200 mya, was relatively constant from 200 mya to 100 mya, and then has been increasing since. The present level is back to one similar to that 300 mya. Future global warming may reverse this trend and cause the absorption to decrease down to a level similar to when the dinosaurs roamed (100 mya).
Sound system installed in a central bus station
Authors: Beristain Sergio
Published: September 2012

As a result of a new administration board planning in the Central long range Bus Station located in a mayor city, it was installed a public address system, together with a small modification of the visible building materials within the station, for the purpose of easy understanding of; bus departure confirmation, people and stuff localization and general information to passengers, workers and visitors of the station. The system involved a distributed sound system with dozens of loudspeakers strategically located with reasonable, non-disturbing, sound pressure level generation by each one, which enhanced the intelligibility of the spoken messages well over the average for the Central Bus Stations system in the country. The system performed at a comfortable sound level, just enough to overcome the noise level within the central, which together with a reduced reverberation time allowed for proper effortless understanding of the emitted messages. Mayor contributors for the obtained results were careful design, sound equipment quality, sound absorption materials, guided installation and luck.
Active acoustics in a restaurant: A case study
Authors: Germain Pierre , Schwenke Roger W.
Published: September 2012

Loud restaurants have become sufficiently common that newspapers have begun rating the sound levels of restaurants. A Zagat survey in 2011 found that diners ranked noise as their second-highest complaint behind service. Comal Restaurant in Berkeley California is the first to use a combination of active and passive acoustic treatments to control the reverberation time of the dining area.
Review of an arena's acoustical and electroacoustical design upgrades
Authors: Scheirman David
Published: September 2012

Sports arenas and stadiums are an important economic part of the urban centers in which they are located. For cost efficiency, acoustical elements of the original architectural design should complement and support the facility’s requirements for communication and public address equipment. Multi-purpose use requirements are examined for one such facility, an indoor arena which measures 950,000 square feet (88,257.9 m2) of total space, with a 94-foot (28.7 m) by 200-foot (61.0 m) arena floor. It hosts over 250 events and nearly 4,000,000 guests each year, seating 18,000-20,000 attendees per event based upon type and format. The timeline is reviewed over which acoustical and electroacoustical studies, upgrades and modifications were carried out. Original-construction sprayed cellulose acoustical insulation was enhanced by installation of lapendary panels to reduce reverberation time and sound intensity levels in target frequency bands. Finally, with the installation of a new multi-array line-array type loudspeaker system, the venue has achieved increased speech intelligibility and improved audience-perceived quality of sound reproduction for both sports and entertainment production events. The upgrades have helped to enhance its global reputation as a multi-functional space. The building was voted Venue of the Year at the 2011 Stadium Business Awards.
Bowhead whales and airgun pulses: Detecting a threshold of behavioral reaction
Authors: Blackwell Susanna B. , McDonald Trent L. , Nations Christopher S. , Thode Aaron M. , Kim Katherine H. , Greene Charles R. , Macrander Michael A.
Published: September 2012

Previous work has shown that bowhead whales cease calling when near (<40 km) seismic exploration activities involving airguns. The aim of this study is to estimate the received level threshold for the onset of this behavior (cessation of calling). The analysis relied on data collected during late summer of 2007-2010 by up to 40 Directional Autonomous Seafloor Acoustic Recorders (DASARs) in the Beaufort Sea. About 98,000 localized calls and hundreds of thousands of airgun pulses were included in the analysis. For each 10-min period of data collected at each recorder, each year, the cumulative sound exposure level (CSEL) from airgun pulses was calculated and paired with the number of calls concurrently localized within ~3.5 km of each DASAR. Poisson regression was then used to estimate the threshold of airgun sound exposure received at the whales when call cessation begins. The CSEL threshold was found to be near 124 dB re 1 μPa2 s (95% confidence intervals = 119-129 dB). For an airgun array firing every 10 sec, this corresponds to a received single pulse SEL at the whale of ~106 dB re 1 μPa2 s. [Work supported by Shell Exploration and Production Company.]
Arctic marine mammal passive monitoring and tracking with a single acoustic sensor
Authors: Arvelo Juan I.
Published: September 2012

The Arctic Ocean is a unique environment in the number of physical mechanisms that may be potentially exploited with much simpler acoustic systems than would be required in other oceans. The Arctic sound speed profile forms a surface duct with favorable cylindrical-spreading for near-continuous detection of marine mammal vocalizations. This ducted waveguide exhibit low seasonal variability, particularly under the ice cap, forcing under-ice sound to heavily interact with this rough elastic stratified boundary. The ice roughness introduces steeper slopes that enhance water-to-ice sound penetration [Arvelo, POMA 2012]. The ice elasticity is responsible for the excitation of a radially polarized longitudinal wave and a transverse-horizontal shear wave with group velocities around 2700-3000 m/s and 1550-1650 m/s, respectively. A third dispersive flexural vertical plate wave propagates at much slower speeds (<1200 m/s) at low frequencies [Stein, Euerle & Parinella, JGR 1998]. Vocalization distance may be estimated from the time delays between the three wave types via blind deconvolution, while an arctangent bearing-estimator may increase the azimuthal localization resolution for high SNR vocalizations [Maranda, Oceans 2003]. Therefore, the unique Arctic environment is well suited for passive marine mammal monitoring and tracking with just a single ice-embedded geophone or under-ice vector sensor.
Right whale versus bowhead whale gunshot calls in the Bering Sea
Authors: Berchok Catherine L. , Crance Jessica L. , Thompson Jessica L. , Grassia Stephanie L. , Clapham Phillip J. , Wright Dana L. , Lammers Marc O.
Published: September 2012

The Bering Sea is an important area for many cetaceans. It functions as both summer feeding grounds for some species like humpback and right whales, and wintering grounds for more northern species such as bowhead and beluga whales. Passive acoustics is an important tool for monitoring the presence of these and other species in the Bering Sea, although similarities in call characteristics among species can create confusion. For example, gunshot calls are produced by both right and bowhead whales. Recordings made in the Bering Sea (2007-2011) have been analyzed for the presence of gunshot calls. The spatio-temporal distribution of these calls is compared to that of more ‘standard’ bowhead and right whale calls. With the inclusion of information on historical range, migration patterns, and ice coverage, a tentative separation of the two species is proposed. Call characteristics and contextual information from the resulting subsets of data are then examined and compared with data confidently attributed to each species. Whether right and bowhead whale gunshot calls can be discriminated with sufficient reliability to include in spatio-temporal distribution analyses, and what added value this call type gives over using only ‘standard’ call types, will be discussed.
Cetacean vocalizations and anthropogenic noise levels in polar waters of the Atlantic
Authors: Nieukirk Sharon L. , Klinck Holger , Klinck Karolin , Mellinger David K. , Dziak Robert P. , Matsumoto Haruyoshi
Published: September 2012

Obtaining baseline information on the distribution of endangered species in polar waters is important as climate change may adversely affect this fragile environment. In 2009 we began an acoustic survey in the Greenland Sea and Fram Strait to monitor the low-frequency calls from marine mammals using these waters. We also documented sources and levels of ambient noise as these will change as human use of the area increases. We recorded the vocalizations of numerous marine mammals; here we report our results for fin (Balaenoptera physalus), blue (B. musculus), sei (B. borealis) and sperm (Physeter macrocephalus) whales. The 20 Hz pulses of fin whales were recorded in the fall and early winter months. Sounds from blue whales, sperm whales and sei whales were recorded primarily in the summer and early fall. Background noise levels were dominated by the sounds from seismic airguns during the spring, summer and fall; during summer these sounds were recorded in all hours of the day and in all days of a month. Future increases in oil exploration and ship traffic coincident with melting sea ice will increase ambient noise levels, potentially affecting the numerous species of vocalizing whales using this area.
Spatio-temporal distribution of ice seals in the Chukchi Sea using underwater vocalizations: Special focus on male bearded seals
Authors: Frouin Heloise , Mouy Xavier , Delarue Julien , Martin Bruce , Hannay David
Published: September 2012

Underwater vocalizations of ringed, ribbon and bearded seals were recorded over a wide region of the northeastern Chukchi Sea between July 2007 and October 2011. Ringed seals were identified by their barks and yelps, ribbon seals by their sweeps and puffing sounds and bearded seals by their trills, ascents and moans. Ringed seal vocalizations were detected in all months of the year, whereas vocalizations from ribbon seals occurred only in October and November. To determine the seasonal variation in the frequency of occurrence of male bearded seal vocalizations throughout a year 20-min recordings were analyzed to determine call counts between 02:00 and 06:00 every 3 days. Bearded seal acoustic detections increased progressively from August to March, peaked between April and June but were essentially absent in July. Outside of the mating period (April - June) the frequency of occurrence of vocalizations varied on a diel cycle and was higher during periods of darkness. To determine the influence of diel cycle, the duration of vocalizations and the proportion of each vocal type throughout the mating season 10-min recordings on a 17-20% duty cycle were analysed between April and June every 10 days. Results are currently under review and will be presented.
Spatio-temporal distribution of fin whales in the Bering Sea, 2007–2011
Authors: Thompson Jessica L. , Berchok Catherine L. , Clapham Phillip J. , Lammers Marc O. , Moore Sue E.
Published: September 2012

The National Marine Mammal Laboratory has been collecting passive acoustic recordings of vocalizing marine mammals through much of the southeastern Bering Sea since 2000. The present analysis combines these recordings with those obtained in 2007 from a North Pacific Research Board-funded study (Stafford and Mellinger) to determine the long-term spatio-temporal distribution of fin whales throughout the Bering Sea shelf. A total of 28 moorings (19 Autonomous Underwater Recorders for Acoustic Listening (AURALs); 9 Ecological Acoustic Recorders (EARs)) were deployed year-round from October 2007 to September 2011 at varying depths and locations along the Bering Sea shelf, from Umnak Pass to just south of St. Lawrence Island. Preliminary analyses show an annual southward movement of calling fin whales in winter, seemingly associated with the expanding ice edge; these results will be compared with 1-day composite ice cover measured by the Advanced Microwave Scanning radiometer for the Earth Observing System (NOAA Coastwatch). Furthermore, the results show a considerably lower number of calls detected south of St. Matthews compared to the other mooring locations. In addition, overall fin whale seasonal calling trends along and between the 50m and 70m isobaths, and the species’ use of Umnak Pass and Unimak Pass will be described.
Contributions of airgun activity to the ice-free ambient noise environment of the shallow Beaufort Sea between 2007 and 2011
Authors: Thode Aaron , Mathias Delphine , Kim Katherine H. , Blackwell Susannna B. , Greene Charles R. , Macrander Michael
Published: September 2012

Every year since 2007 a collection of at least 35 “Directional Autonomous Seafloor Acoustic Recorders” (DASARs) have been deployed across a 280 km swath of the Beaufort Sea continental shelf, in water depths between 15 and 50 m. The ability of these instruments to estimate the arrival azimuth of transient signals has facilitated the development of an automated algorithm for the detection of airgun activity. This algorithm has been applied to five seasons of data, and in this presentation the contributions of this activity to the overall ambient noise background of the ice-free shallow-water Beaufort environment will be quantified with a variety of metrics, in terms of both level (peak-to-peak, rms, sound exposure level), frequency, and time (intervals and fraction of time present). During some years, up to four airgun operations could be detected simultaneously, and a random one-second time sample yielded a 40% chance of containing an airgun signal, but the levels detected are generally within the bounds of natural wind-driven ambient noise levels. This dataset provides useful empirical insight into discussions about the cumulative effects of anthropogenic activity on an environment extensively used by several marine mammal species. [Work sponsored by the Shell Exploration and Production Company.]
Standing surface acoustic wave technology for cell and organism manipulation
Authors: Lin Sz-Chin S. , Huang Tony J.
Published: September 2012

Manipulation of particles, cells, and organisms is essential to many fundamental biological studies. For example, the ability to precisely control the physical settings of biological objects allows scientists to investigate the interactions between molecules, cells, or cell and its environment. Acoustic-based particle manipulation techniques possess non-contact and non-invasive natures and have rapidly become key enablers for many emerging lab-on-a-chip biomedical applications. We, BioNEMS lab at Penn State, have developed a series of standing surface acoustic wave (SAW) based acoustic tweezers that can dexterously manipulate a wide range of cellular-scale objects. This technology uses standing SAW induced acoustic radiation forces to trap suspended biological objects, whose physical location/orientation can then be dynamically changed by adjusting the parameters (e.g. frequency and amplitude) of the standing SAW. Simply by tuning the AC electrical signals, our system can perform sophisticated cell patterning, focusing, reorientation, separation, sorting, transportation, and stretching without direct contact. We show that our system can be seamlessly integrated with other on-chip devices and is fully compatible with fluorescence and confocal microscopies. The versatility, simplicity, low power consumption, non-contact and non-invasive natures render our system an excellent platform for a wide range of applications in the biological, chemical, and physical sciences.
Microfluidic air-liquid cavity acoustic transducers for point-of-care diagnostics applications
Authors: Lee Abraham , Patel Maulik
Published: September 2012

Microfluidic devices with “side channels” that trap air enable acoustic energy coupling and acoustic streaming into the main channel. This basic configuration is versatile and can be designed as a microfluidic pump, mixer, particle trap, cell sorting switch, and sample separation component. These multiple functions are integrated on a microfluidic platform and provides rapid and specific diagnostics of infectious diseases based on the immune response detected in a drop of blood. A second implementation of this concept is to utilize microfluidic produced lipid microbubbles that respond to acoustic energy as ultrasound contrast agents with drug carrying payload and molecular ligand targeting that can detect and treat molecular diseases such as cancer and cardiovascular diseases. This talk will introduce both of these microfluidic acoustic transducer projects in my lab.
Cell lysis using acoustic cavitation bubbles in microfluidics
Authors: Tandiono Tandiono , Ohl Siew-Wan , Chin Cara Sze-Hui , Ow Dave Siak-Wei , Ohl Claus-Dieter
Published: September 2012

Analysis of intracellular contents, such as proteins and nucleic acids, in a micro-scale system is gaining its importance in biomedical research. However, an efficient cell lysis needs to be achieved before the analysis can be carried out. The standard lysis methods in microfluidics, for example: by means of chemicals, thermal, or electrical lysis, suffer from the undesirable temperature increase and cross-contamination, which may lead to the denaturation of proteins or interfere with subsequent assays. Here, we present a technique to mechanically lyse microbial cells using acoustically driven cavitation bubbles in a polydimethylsiloxane based microfluidic channel attached on a glass slide. The cavitation bubbles are created by exciting gas-liquid interfaces in the microchannel into nonlinear interface instability with ultrasonic vibrations. The strongly oscillating bubbles create regions with intense mixing and high shear stress, which can deform and rupture the nearby cells. Escherichia coli (bacteria) and Pichia pastoris (yeast) cells are completely lysed in less than 0.4 seconds and 1.0 second, respectively. The temperature increase of the samples during the ultrasound exposures is less than 3.3 °C. Fluorescence intensity measurements and real-time polymerase chain reaction (qRT-PCR) analysis suggest that the functionality of the harvested protein and genomic DNA is maintained.
Structures formed by ultrasonic standing waves in active fluids and suspensions
Authors: Hoyos Mauricio , Castro Angelica , Clément Eric , Rousselet Annie , Bazou Despina , Wang Wei , Mallouk Thomas
Published: September 2012

The acoustic radiation force concentrates particulate materials at the nodes or antinodes of an ultrasonic standing wave (USW), in function of different physicochemical parameters: size, shape, density or elastic properties. Thus, frequencies from 0.5 to 10 MHz are adapted for manipulating micron-sized particles, cells, bacteria, vesicles, drops, bubbles and even colloidal species. The interaction of different species with the ultrasonic radiation field generates levitation, aggregation or coalescence. In this presentation, new behaviors will be presented in active fluids: bacteria bath and self-propelled metallic micro-cylinders. Leaving bacteria in culture medium undergoing the USW field show a dynamics inducing complex structures. USW propel, rotate, align and assemble metallic micro-rods (2 µm long and 330 nm diameter) in water as well as in solutions of high ionic strength, generating “self-acoustophoresis”. Finally, new possibilities for controlling aggregation forming 2D and 3D particle and cancer cells structures using pulsed ultrasound will be shown.
Acoustic trapping with seed-particles for submicron particle enrichment
Authors: Hammarström Björn , Ekström Simon , Laurell Thomas , Nilsson Johan
Published: September 2012

Acoustic trapping in disposable borosilicate capillaries utilize ultrasonic forces to capture/retain micro-particles or cells against fluid flow in a microfluidic-channel. A miniaturized ultrasonic transducer is used to locally excite a 4-MHz cross-sectional resonance in the capillary, creating an acoustic field gradient for retention of cells in non-contact mode. Due to competition between fluidic drag from induced acoustic streaming and primary radiation force the smallest particle size addressable with the trapping system is limited. Here, the typical transition occurs at single-micron particle diameters. However, trapping of single- or sub-micron biological species has highly relevant applications such as enrichment or purification of bacteria or viruses. This work investigates the influence of in-trap particle concentration on the trapping, and it is found that elevated concentrations allow capture of submicron particles. By preloading the acoustic trap with micron-sized seed-particles capture of submicron particles even at low concentrations is enabled. Using this technique, we demonstrate single event capture of bacteria as well as capture of 100nm particles. To provide analytical readout for identification/analysis of the trapped particles the acoustic trap is interfaced with a MALDI-MS instrument. Here, the acoustic trapping capillary is operated in aspirate/dispense mode allowing easy and flexible handling of small sample volumes.
Ultrasonic standing waves for dynamic micro-array cytometry
Authors: Wiklund Martin , Christakou Athanasia , Ohlin Mathias , Önfelt Björn
Published: September 2012

We describe a novel platform for dynamic micro-array cytometry (DMAC), i.e., parallel screening of individual cell-cell interactions based on ultrasonic standing wave aggregation and positioning of cells in a multi-well microplate. Upon ultrasound actuation, clusters containing one or a few cells are quickly formed and retained in a precise location synchronously in each of the 100 wells on the microplate. By combining the acoustic cell handling tool with high-resolution fluorescence microscopy, detailed time-lapse monitoring of individual cell-cell interactions in a highly parallel manner is possible. Of particular interest in our group is to study the long-term interaction between natural killer (NK) cells and different target cells at the level of single cells. In this talk we demonstrate both theoretically and experimentally how to design a microchip capable of trapping and positioning individual cells by ultrasound in a highly parallel manner, and with a spatial accuracy of the order of a cell diameter. We quantify the cell cluster motility with and without retained ultrasound exposure during 17 h, and we report on the viability of cells when exposed to continuous ultrasound for up to three days. Finally, we quantify the heterogeneity of NK cells’ cytotoxicity against cancer cells.
Development of a computational model to predict cranial resonance shifts due to changes in intracranial pressure
Authors: Piacsek Andrew A. , Abdul-Wahid Sami
Published: September 2012

A possible method for noninvasively monitoring changes in intracranial pressure is to measure changes in skull resonance frequencies. Recent measurements of the vibrational response of a spherical aluminum shell clearly demonstrate that resonance frequencies shift higher as the internal pressure is increased [Piacsek et al, J. Acous. Soc. Am, 131, EL506-510 (2012)]. The frequency shift is approximately linear with the applied pressure, regardless of whether the shell is filled with air or water, and circumferential modes exhibit larger resonance shift than longitudinal modes. A computational model of a fluid-filled thin shell subject to acoustic stimulation was developed using the COMSOL multi-physics software to investigate the role of shell material and geometry in resonance shifts. The model predicts frequency shifts comparable to those observed in the spherical aluminum shell. Preliminary computational results for a spherical shell made of bone-like material, as well as for asymmetric and nonuniform shells, will be presented.
Numerical analysis of nonlinear standing waves in two-dimensional acoustic resonators
Authors: Ning Fangli , Li Xiaofan , Wei Juan
Published: September 2012

High amplitude nonlinear standing waves in acoustic resonators have been used in many engineering applications ranging from microfluidic devices for biomedical research, acoustic compression, to acoustic seal. The distribution of physical properties inside two-dimensional resonators is very useful for developing the application of nonlinear standing waves. Most of the previous numerical studies were limited to one-dimensional resonators, and analyzed standing waves with an assumption: the physical variables are assumed as finite sums of basic functions. In the study, the formation of the standing waves in the two-dimensional resonators is computed in the time domain from the initial position at rest without any predefined standing waves. The two-dimensional unsteady compressible Navier-Stokes equations and the state equation for an ideal gas are employed. This study extends the traditional pressure based finite volume SIMPLEC scheme for solving the equations. Initially, the pressure waves predicted in a two-dimensional cylindrical resonator are excellent agreement with the results obtained with pervious numerical methods in particular finite element and finite difference method. Next, we also investigate the velocity waveforms, and find that the sharp velocity spikes appear at the two ends of the resonator. Finally, the distribution of physical properties inside a two-dimensional cylindrical resonator is obtained.
Underwater sound transmission through water tunnel barriers
Authors: VanOverloop Matthew J. , Dowling David R.
Published: September 2012

In hydrodynamic test facilities with flowing water, receiving hydrophones are commonly placed behind a solid barrier to reduce flow noise from buffeting and turbulence. However, acoustic waves from the sound sources under study, such as cavitation bubbles, may propagate through the barrier as compression or shear waves, and the presence of the second wave type distorts signals recorded by the hydrophones. Such distortion depends on the structural characteristics of the barrier and the source-receiver geometry, and it may lead to sound-source detection and localization errors. This presentation describes results from a combined experimental and computational effort to understand the sound transmission characteristics of plastic and metal barriers typically used in water-tunnel testing. The experiments were conducted in a 1.0-meter-deep and 1.07-m-diameter cylindrical water tank using a single sound projector, a receiving array of 16 hydrophones, and impulsive (100 micro-second) signals having center frequencies from 30 kHz to 100 kHz. Computations intended to mimic the experiments are completed with the wave number integration software package OASES. Together the computations and experiments allow the most important barrier parameters to be identified. Dependencies of the received signal on the barrier parameters are presented. [Supported by NAVSEA through the Naval Engineering Education Center.]
Estimation of parameters of a head-related transfer function customization model
Authors: Faller Kenneth J. , Hoang Kathleen
Published: September 2012

Head-Related Transfer Functions (HRTFs) are special digital filters used to create the effect of three-dimensional (3D) virtual sound source placement over headphones. The two most common methods of obtaining HRTFs are to either individually measure the HRTFs on specialized equipment (individualized HRTFs) or to create a set of generic HRTFs by measuring them on a mannequin with average anatomical features (generic HRTFs). Individualized HRTFs required specialized equipment that is not readily available to the general public. Additionally, it is known that HRTFs are heavily dependent on our anatomical features. As a result, generic HRTFs produce significant localization errors. A multi-linear model is now available which uses simple anthropometric measurements of the intended user’s anatomy to generate customized HRTFs. These customized HRTFs can be generated without specialized equipment and have improved spatialization over generic HRTFs. However, the anthropometric measurements, which are used as parameters for the customization model, are currently collected manually. In the present work, image processing techniques are used to automatically estimate a portion of the anthropometric measurements of the human pinnae. Analysis of the estimation technique’s performance will also be conducted.