bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiation force on spheres in helicoidal Bessel beams modeled using finite elements.
Authors: Thiessen David B. , Zhang Likun , Marston Philip L.
Published: October 2013

Analysis of the scattering of sound by spheres centered on ordinary and helicoidal (higher-order) Bessel beams [P. L. Marston, J. Acoust. Soc. Am. 124, 2905–2910 (2008)] makes it possible to evaluate the radiation force on spheres centered on the beam in an ideal inviscid fluid. Potentially surprising results include cases where the radiation force is directed opposite the propagation direction of both types of beams [P. L. Marston (submitted for publication)]. For potential biomedical applications such as drug delivery, it would be necessary to know if a small transverse displacement of the sphere from the beam’s axis causes a radiation force that pushes the sphere toward (or away from) the axis of the beam. Three-dimensional finite elements were applied to that problem. To trust FEM calculations of the radiation force with helicoidal beams, it was first necessary to verify that analytical values for the axial force are recovered in the on-axis helicoidal case since only the zero-order beam had been previously studied [D. B. Thiessen and P. L. Marston, J. Acoust. Soc. Am. 122, 3025 (2007)]. Cases were found where displacement of a sphere from the beam axis causes a transverse restoring force. [Supported by ONR and NASA.]
An acoustic study of /w/ in Korean.
Authors: Jun Sun-Ah , Bishop Jason B.
Published: October 2013

This study examines acoustic characteristics of Korean /w/. Modern Korean is claimed to have four /w/ diphthongs: /w/ before two front vowels (/wi, we/) and two back vowels (/wa, wʌ/). The two front diphthongs are a product of a more recent sound change from front rounded monophthongs, high /y/ and mid /o//. However, a pilot study shows that the phonetic realizations of /w/ before front vowels differ from those before back vowels, and also differ whether /w/ comes after a consonant (CwV) or not (wV). It was found that /w/ before front vowels is similar to a labial-palatal approximant, especially after a consonant, showing a trace of front rounded monophthongs. To confirm this finding, a large set of data was collected from six Korean speakers and the acoustic realizations of Korean /w/ were compared with those of French labial-palatal and labial-velar approximants produced by six French speakers. The implication of the results in the phonological system will be discussed.
Tone space reduction in Mandarin Chinese.
Authors: Berry Jeffrey
Published: October 2013

Work on clear versus conversational speech has shown that speakers expand the vowel space in clear speech, which maximizes the perceptual contrast, making it easier for listeners to parse the speech signal. This study investigates how the realization of lexical tones changes for different speech tasks, and whether it is sensitive to the number of repetitions of the same word in a conversation. Native Mandarin speakers participated in a map task in which they were instructed to explain the route on the map to a partner. The first and last tokens of each target word were extracted from the dialogues and compared to the same word read from a list. Pitch and duration were normalized and quadratic curve fitting was performed on the test items. Results of statistical analyses show that contour tones from later occurrences of the target words have a smaller slope, are more linear, and tend to have pitch values closer to the overall average pitch of the speaker. In other words, all tones are realized closer to a midlevel tone when they have been previously mentioned in the conversation. In this sense, there is a contraction of the tone space for later tokens.
A corpus search methodology for focus realization.
Authors: Howell Jonathan , Rooth Mats
Published: October 2013

We describe a methodology for investigating the semantic-grammatical conditioning and phonetic realization of contrastive intonation using a web harvest of particular word strings followed by grammatical and acoustic analysis. A commercial audio web search engine using speech recognition retrieved 179 MP3 files purportedly containing a token of the string “than I did.” In this comparative clause fragment, contrastive focus commonly falls on the subject (she did more than IF did), on “did” (I wish I had done more than I didF), or following (I said more now than I did beforeF). The 96 true tokens of “than I did” were classified into the categories “subject,” “did,” and “following” by grammatical and semantic criteria. For each token, 5 segment intervals were hand-annotated and more than 300 acoustic parameters extracted using a Praat script. SVM machine learning classifiers were trained that identify focus classes by acoustic criteria. On a 10-fold cross-validation test, the classifier achieves 90.2% accuracy in discriminating the dominant “subject” and “following” classes. In a listening task, human subjects achieved comparable accuracy of 90.3‘ given only the acoustic target “than I did.” Stepwise logistic regression revealed measures of duration, f0, intensity, formants, and formant bandwidths among the significant factors.
The production of English lexical stress by Thai speakers.
Authors: Jangjamras Jirapat , Wayland Ratree
Published: October 2013

The major goal of this work is to report acoustic correlates of English lexical stress produced by native and second language learners of American English. Fifteen native Thai speakers and fifteen native English speakers were asked to concatenate two English monosyllabic nonwards into one disyllabic word and to produce stress on either the first or the second of the resulting disyllables. Disyllabic English nonwords were constructed by pairing CVO, CVVO, CVV, CVS, and CVVS monosyllables. It is predicted that Thai speakers’ production of English lexical stress will be influenced by Thai prosodic system including Thai tonal distribution rules which are constrained by syllabic structure, the presence of fixed final-stress placement, and the use of duration as the primary cue in L2 English lexical stress production. The acoustic parameters measured included vowel duration, intensity, fundamental frequency, and formant frequencies (F1, F2, F3). The ratio values of these measurements between stressed and unstressed syllables will be correlated with stress identification scores obtained from native English listener judges to examine the amount of acoustic information required for accurate perception of stress location by native listeners.
Effects of speaker gender on voice onset time in Korean stops.
Authors: Oh Eunjin
Published: October 2013

Several studies have shown that the voice onset time (VOT) of English stops varies as a function of speaker sex. The overall trend indicates that females exhibit longer VOT values than males for voiceless stops. The suggested explanations have mainly attributed this difference to physiological or stylistic differences between the sexes. If this is so, we would expect to find identical sex differences in the VOTs of stops in other languages. This study tested 38 native speakers of Korean (19 males and 19 females), who produced fortis, lenis, and aspirated stops in /CVn/ words. The males tended to exhibit longer VOTs than females for most of the syllables, the greatest differences occurring in aspirated stops. The males also exhibited more distinctive distributions in VOT values than the females in Korean. These results indicate that the physiological or stylistic explanations previously suggested are not tenable since there is no automatic reason why VOT values for voiceless stops are, in general, longer for females in English, but longer for males in Korean. Sociophonetic factors may explain why languages can exhibit opposing trends in gender differences in temporal acoustic properties such as VOTs.
Quantifying the time-varying coordination between performer and audience.
Authors: Barbosa Adriano , Munhall Kevin G. , Yehia Hani C. , Vatikiotis-Bateson Eric
Published: October 2013

This study examines the coordination that occurs ubiquitously during behavioral interaction (e.g., linguistic, social, musical). Coordination, however, does not imply strict synchronization. Musicians in a quartet, for example, will deviate slightly from the measured beat, alternately playing slightly ahead or behind. This paper showcases a new algorithm for computing the continuous, instantaneous correlation between two signals, at ANY temporal offset, resulting in a two-dimensional mapping of correlation and temporal offset that makes it possible to visualize and assess the time-varying nature of the coordination. The algorithm is demonstrated through analysis of the extraordinary performer-audience coordination evoked by Freddie Mercury during the rock group, Queen‘s, Live Aid Concert at Wembley Stadium in 1985.
An acoustic analysis of /æ/ variation and its relationship to perceived sexual orientation in American English.
Authors: Munson Benjamin , Hall Kathleen Currie , Smith E. Allyn
Published: October 2013

Munson et al. [J. Phonetics (2006)] found that 11 self-identified gay and 11 heterosexual men produced different variants of the vowel /æ/, with gay men producing lower, more retracted variants and heterosexual men producing higher, more tense variants. Listeners’ performance in a perception task in which they rated these talkers’ sexual orientation was correlated with these measures: talkers with higher, more-tense /æ/ were rated as sounding more heterosexual than talkers with lower, more retracted /æ/. However, Smith et al. [New Ways of Analyzing Variation (2008)] found the opposite pattern in an experiment in which listeners rated the sexual orientation of productions by 10 trained talkers of sentences containing either tense or retracted /æ/ variants. A different group of listeners showed the same pattern when rating the /æ/ words excised from these sentences, though these listeners replicated Munson et al.’s original finding when presented with the /æ/ words from the original 22 talkers. An attempt to reconcile these findings is made through detailed acoustic analysis of the /æ/ productions in the two experiments. Results underscore the importance of doing careful acoustic analyses in concert with careful phonetic transcription when conducting experiments on perception of social variables and speaker attributes.
A generalized linear filtering approach for sonar receivers.
Authors: Sharma Nabin S. , Buck John R.
Published: October 2013

Active sonar systems operating in realistic environments face the challenge of simultaneously detecting and resolving multiple targets. Receiver signal-to-noise ratio gain and main-lobe width of the receiver response to the transmitted signal limit the detection and resolution capability of an active sonar receiver, respectively. A matched filter is commonly used for target detection to exploit its optimal detection property. Theoretically, an inverse filter achieves optimal resolution and can be used to resolve targets. In practice, the inverse filter is difficult to implement and requires unrealistically high signal-to-noise ratio to perform well. For an active sonar receiver operating in a cluttered environment with closely spaced targets, a matched filter might not resolve some targets and an inverse filter could not detect some targets. For such environments, a generalized linear filtering approach is proposed. This new approach combines the matched and inverse filter properties in a controlled manner to achieve smooth trade off between detection and resolution. In simulation, the generalized linear filter output is compared with the matched and inverse filter outputs to demonstrate the advantages of the proposed filter. In addition, receiver operating characteristics of the filters confirm the improved performance of the generalized linear filter. [Work funded by ONR Code 321US.]
Automatic classification of underwater targets using fuzzy-cluster-based wavelet signatures.
Authors: Ou Hui , Allen John S. , Syrmos Vassilis L.
Published: October 2013

A novel active acoustic underwater target recognition approach is applied to simulated mine-like targets. A feature extraction and integration method is introduced based on the continuous wavelet transform (CWT) and the Gustafson-Kessel (GK) clustering algorithm. CWT projects the acoustic signals onto the time-scale space, and the time-scale signatures are represented by a number of clusters. A modified GK clustering algorithm allows for specific enhancements: (i) autoadjustment of the shape of the clusters according to the time-scale patterns and (ii) autovalidation of the optimum number of clusters. The feature integration encompasses the application of the clustering analysis N times. The resulting cluster centers are combined and overlaps are eliminated. Using this method, the target of interest is characterized by an integrated clustering distribution, or a feature template. A classification scheme is developed by matching the clustering distributions of the echoes received from an unknown target with the existing feature templates. White Gaussian noise has been added to the signals to simulate the interface of an ocean floor. The recognition rate varies from 72–98% for a SNR between 5–15 dB.
Channel simulation for predicting acoustic modem performance.
Authors: Porter Michael B. , Hursky Paul , Siderius Martin
Published: October 2013

Acoustic modems usually provide the link in modern Distributed Netted Systems. However, their performance is strongly affected by the ocean weather as both the propagation medium and the source of background noise. Understanding these effects is important in pre-experiment planning, real-time adaptation, and retrospection (to ensure appropriate lessons are learned for future deployments). To this end, we have developed a channel simulator called VirTEX (Virtual Timeseries Experiment) that includes Doppler effects due to platform and ocean surface dynamics. VirTEX, in turn, is a component of the AComms Advisor, which provides links to ocean forecasts and other environmental information and uses HIL (Hardware in the Loop) testing to include a faithful modem simulation. This talk will discuss the process, as well as progress, in the algorithms.
Synthetic aperture communications exploiting fluctuations of the ocean environment.
Authors: Song H. C. , Hodgkiss W. S. , Kuperman W. A. , Akal T. , Stevenson M.
Published: October 2013

Typically, fluctuations of the ocean environment pose difficulties for high-rate underwater acoustic communications. On the other hand, these fluctuations can be exploited in synthetic aperture communications (SAC) that take advantage of the relative motion between a transmitter and a receiver to create the equivalent of an array aperture. SAC requires that the channel impulse responses are sufficiently different from each other between transmissions for diversity combining to be effective. Rapid channel variations facilitate a shorter interval between transmissions resulting in a shorter integration time to achieve the desired diversity. This paper demonstrates high-rate SAC in shallow water exploiting fluctuations of the ocean environment.
Basic research on time-reversal communication with a moving source-receiver.
Authors: Shimura Takuya , Watanabe Yoshitaka , Ochi Hiroshi , Hattori Takehito
Published: October 2013

A basic research on time reversal, to be used for communication with a long cruising AUV, has been researched by our research group. In such application, it is preferred to maintain its cruising speed. However, time reversal does not compensate the effect of moving source-receiver in principle. So in this study, simulations with a normal mode method considering the effect of source-receiver movement are executed in which the carrier frequency is 500 Hz and symbol rate is 100 bps. The method of combining time reversal and adaptive decision feedback equalizer is applied. In both cases of shallow water and the deep ocean, demodulation cannot be realized with only time reversal as expected, while the proposed method achieves communication at the moving speed up to 1.0 m/s.
Impact of bottom type on orthogonal frequency division multiplexing in underwater communications.
Authors: Parrish Nathan , Roy Sumit , Arabshahi Payman
Published: October 2013

The impact of bottom sediment type in relation to acoustic communications via orthogonal frequency division multiplexing (OFDM) is shown via experimental results and simulation. Experimental data from Lake Washington, Seattle with a “silty clay” bottom show that the multipath delay spread is longer at 250 m than at 4 km. This results in better OFDM performance at the longer range. Similar results are shown via simulation using a channel model developed from Bellhop, a Gaussian Ray tracing tool [M. Porter, “Bellhop Gaussian beam/finite element beam code,” Available: http://oalib.hlsresearch.com/Rays/index.html (2007)]. Through simulation, results are also shown under similar conditions to the experiment but with varying bottom type. The results show that the performance of OFDM signaling is dependent on the bottom type as well as specific source/receiver geometry. [Work supported by NASA ESTO.]
Capacity of orthogonal frequency division multiplexing systems over fading underwater acoustic channels.
Authors: Polprasert Chantri , Ritcey James A. , Stojanovic Milica
Published: October 2013

The channel capacity bounds of orthogonal frequency division multiplexing (OFDM) systems over the underwater (UW) acoustic fading channel as a function of the distance between the transmitter and receiver are investigated. The upper bound is obtained under perfect channel state information (CSI) assumption at the receiver. The lower bound is obtained under imperfect CSI at the receiver. The reduction from the upper bound is due to the linear minimum mean square prediction error. The UW channel deviates from the wide sense stationary and uncorrelated scattering (WSSUS) model commonly used for small bandwidths. Frequency-selectivity is incorporated due to the acoustic propagation into each arrival path between the transmitter and receiver. This leads the UW channel to be modeled as a frequency-dependent doubly spread fading channel characterized by the wide sense stationary and correlated scattering (WSS-non-US) fading assumption. Both Rayleigh and Ricean fading assumptions are investigated in the model. Results from the model show a gap between the upper and lower bounds that depends not only on the ranges and shape of the scattering function of the UW channel but also the distance between the transmitter and receiver. The model for the scattering function was confirmed from experimental data.
Multichannel combination investigations for differential frequency hopping transmissions in shallow water.
Authors: Egnor Dianne E. , Edelson Geoffrey S. , Cazzanti Luca , Hsieh Julia
Published: October 2013

Underwater acoustic communication requires waveforms that are robust to the signal distortions caused by the acoustic channel. Many waveforms used for this purpose require the transmission of training symbols that span the intersymbol interference to “learn” and compensate for these channel effects. These waveforms also require exacting coordination between the transmitters to avoid multiple access interference. Differential frequency hopping (DFH) is a fast frequency hopping, digital signaling technology that requires minimal information at the transmitter to communicate in the underwater channel. DFH has the desirable performance features of noninterfering spread spectrum operation, spectral reuse, and fading and interference resistance. This presentation describes the baseline autosynchronizing, single-user DFH decoder for a multiple hydrophone receiver and investigates two processing techniques incorporated for shallow-water multiuser applications: fading mitigation and multiuser interference mitigation, as implemented in conjunction with array processing. We present the performance of the baseline DFH decoder in terms of bit error rate with and without these enhancements on single- and multiuser data collected at sea during the 2008 Surface Processes and Acoustic Communications Experiment (SPACE08).
From toy to tool—advanced auralization procedure in daily design work.
Authors: Ahnert Wolfgang , Feistel Stefan
Published: October 2013

Since more than 20 years simulation procedures are more and more common, but the auralization procedure is considered mainly as a toy. The reason for this relates partially to the efforts needed to get real auralized sound files. In a previous paper the authors reported about a method to produce high end auralization files. This method allows to use normal head phones to get the right spatial impression without in-head localization. The main reason not to use an auralized sound impression in the daily design work is the time-consuming procedure to calculate true impulse responses (IR) especially in large halls. In this paper new algorithms are reported to calculate IRs in multithread mode with one computer or better via a network with a set of CPUs working in parallel. So calculations in large halls maybe be reduced from 8–10 h with one CPU to 10–20 min with multicore computers. The paper explains the way from the model to high-end auralized files. Some examples demonstrate the quality of these derived binaural files.
The spatial perception of a large pipe organ in various locations in a church computer model is investigated using multiple sources properly spaced within an organ chamber, with each source representing an organ stop.
Authors: Campbell Richard
Published: October 2013

It is surmized that the auralization of a large pipe organ should use multiple sources properly spaced in the organ chamber with each source representing a stop. But at some point in the acoustic environment of the listener, the advantage of such spatial sourcing disappears. A MIDI sequencer is used to generate audio files of a Buxtahuda fugue in six parts using six different stops. The sources are properly spaced within an organ chamber in a large church. Binaural recordings are evaluated at various locations in the church.
Using computer auralization to help prevent major problems relating to room acoustics and electroacoustic sound reinforcement.
Authors: Coffeen Robert C.
Published: October 2013

Computer modeling and computer auralization will produce comparative listening experiences for architects, building owners, and building users based on selected interior surface shapes, interior finish materials, and electroacoustic sound distribution. Auralization can be a significant tool in helping building designers, owners, and users understand potential acoustical problems and the need for proper acoustic and electroacoustic design.
Frequency quantiles and dual harmonic tracking for detection and classification of killer whale calls.
Authors: Veirs Val
Published: October 2013

The Salish Sea Hydrophone Network, www.OrcaSound.net, is operating five streaming hydrophones in the critical habitat of the endangered Southern Resident orcas. Software is being developed that allows each site to sift through the approximately 10 Gbytes of information that are produced each day at each site in order to detect killer whale calls and related sounds. Detection of calls is accomplished via triggering on three time dependent features extracted in real-time from sequential power spectra. One of these three features is derived from the bandwidth between quartiles of the filtered power spectrum. The other two quantify the degree to which the power spectrum has one or two harmonic structures. Features are extracted into feature sets that save the details of each feature: amplitudes; durations; and time variations. A metric has been devised that measures the similarity of different sequences of feature sets. With this metric an unsupervised learning algorithm builds a tree structure that classifies sounds by their similarity. As new calls come in, they either fall into pre-existing groups or create new branches. Automatic reports are made via the Web and e-mail.
Tracking multiple sperm whales with widely spaced bottom-mounted hydrophones.
Authors: Nosal Eva-Marie
Published: October 2013

One dataset from the 2nd Int. Workshop on Detection and Localization of Marine Mammals Using Passive Acoustics Data featured multiple clicking sperm whales recorded for 20 min. Data were recorded on five widely spaced bottom-mounted hydrophones at the Atlantic Undersea Test and Evaluation Center. This dataset is used to develop and apply a model-based time difference of arrival (TDOA) method that is capable of simultaneously tracking multiple animals. Clicks on all hydrophones are detected. For every receiver pair, all possible time-differences of arrival (within reasonable time limits) are formed from the detected clicks. A scatterplot of TDOAs versus time, although noisy due to many false TDOAs formed from incorrectly associated clicks, reveals clear “tracks” of slowly varying TDOAs. These tracks are extracted and input to a TDOA tracking algorithm that gives 3-D likelihood surfaces of whale position. Local maxima in the likelihood surfaces are extracted and clustered to give estimated whale tracks.
Passive acoustic monitoring of fish activity in the Hawaiian Archipelago.
Authors: Fisher-Pool Pollyanna , Lammers Marc O. , Wong Kevin , Brainard Russell E. , Au Whitlow W. L.
Published: October 2013

Fish are an important component of coral reef ecosystems and can be valuable indicators of ecological change on reef environments. Many species of fish produce sounds and are therefore well suited for passive acoustic monitoring. Since 2006, NOAA has been using Ecological Acoustic Recorders (EARs) to monitor coral reef habitats in the main and Northwestern Hawaiian Islands in an effort to develop multi-year time series of biological activity at these locations. Sixteen EARs are presently deployed on reef habitats ranging in depth from 2 to 23 meters. Preliminary results reveal that each site is characterized by a unique composition of acoustically active fish. Many sounds are also common at multiple sites. Different species show considerable variability in their diet and seasonal patterns of activity. The results indicate that long-term acoustic monitoring of fish at these sites is likely to yield useful information about changing patterns of fish presence, behavior, and relative abundance. These metrics can be used to gauge the relative stability of ecosystems and be related to physical, oceanographic, and anthropogenic variables affecting them.
Observed temporal statistics of acoustic travel time and intensity in the South China Sea.
Authors: Chiu Ching-Sang , Miller Christopher W. , Reeder D. Benjamin , Reeves Justin M. , Ramp Steven R.
Published: October 2013

The coupled ocean and acoustic variability in the Northeastern South China Sea basin was monitored using moored oceanographic and acoustic sensors during the 2005-2006 Windy Island Soliton Experiment (WISE). The temperature and current records captured prominent ocean variability at multiple scales, induced by mesoscale eddies, internal tides, and large amplitude internal waves. The latter two were transbasin, propagating from near the Luzon Strait, through the deep basin, onto the northeastern shelf. The concurrent acoustic measurements were attained from the transmission of a 400 Hz, phase-modulated signal along a 166 km path every 15 min. The receptions were processed to give the arrival structure of a pulse and its temporal change over a nine-month period. The observed temporal variability in the statistics of the acoustic travel time and intensity were analyzed using time-series techniques and models with emphasis to elucidate the connection and sensitivity to the observed ocean variability. Results from the analysis are discussed, as they pertain to the ocean processes and those parameters that can potentially be inferred from these types of acoustic transmissions. [The research is sponsored by the Office of Naval Research.]
Acoustic ducting, refracting, and shadowing by curved nonlinear internal waves in shallow water.
Authors: Lynch James F. , Lin Ying-Tsong , Duda Timothy F. , Newhall Arthur E. , Gawarkiewicz Glen
Published: October 2013

Nonlinear internal waves are common on continental shelves and have been shown to have strong effects on acoustic propagation and scattering. Transmissions from previous field work performed in an along-shelf geometry show very strong ducting of low-frequency (50–500 Hz) sound between nonlinear waves. This strong ducting effect is acoustically important. Most all of the acoustic propagation studies of internal waves have used straight line internal wave fronts for individual waves or packets. In our work, we implement a theoretical analysis using the Weinberg-Burridge horizontal rays and vertical modes formalism to study the acoustic ducting, refracting and shadowing of low-frequency sound due to curved internal waves, which seem to dominate in shelf break regions. A three-dimensional parabolic-approximation sound propagation model is also used with consideration of realistic environmental conditions, and the modeling results provide a clear depiction of the underlying physical processes. The oceanographic origin of the internal wave curvature is discussed, as this affects the predictability of the sound speed field. [This work is sponsored by the Office of Naval Research.]
Ultrasound standing wave fields control the spatial distribution of cells and protein in three-dimensional engineered tissue.
Authors: Garvin Kelley A. , Hocking Denise C. , Dalecki Diane
Published: October 2013

The application of ultrasound standing wave fields (USWFs) to cell suspensions results in the radiation force-mediated movement of cells to areas of the field separated by half-wavelength intervals. In this study, USWF-induced cellular arrangements were maintained after removal of the sound field by polymerization of a collagen type-I solution around the organized cell bands. Using a water tank setup, cell suspensions of varying concentrations were exposed to a 1-MHz, continuous wave USWF for 15 min, during which time collagen polymerization occurred. An acoustic pressure amplitude of 0.2 MPa was used to achieve the USWF-induced cell organization. Compared to sham samples with a random cell distribution, cell viability was not adversely affected by USWF exposure. The organization of cells into a banded pattern within the collagen gels resulted in a significant two-fold increase in cell-mediated gel contraction, suggesting that USWF-induced cell organization leads to differential extracellular matrix remodeling. Protein organization within the tissue constructs was further controlled by USWF-mediated collocalization of soluble fibronectin to cell bands. These technologies have applications to the fabrication of tissue analogs with desired tissue characteristics for the repair or replacement of diseased or injured tissues and organs in the field of tissue engineering.
The piezoelectric thickness mode hydrophone using tonpilz structure for deep-sea application.
Authors: Sung Min , Lee Haksue , Moon Wonkyu
Published: October 2013

A piezoelectric thickness mode hydrophone for deep-sea application using tonpilz structure was designed, and its macroprototype was made as a preliminary for the micromachined version. Several types of micromachined thin-diaphragm sensors for hydrophone application have been reported. They have two issues in deep-sea applications. One is a sensitivity problem. To enhance the sensitivity, a cone structure for sound pressure amplification was placed between the clamped diaphragm and the piezoelectric square plate. To evaluate the effect of the cone structure on sensitivity, which was motivated by tonpilz structure, an air-backed prototype was made using aluminum and piezoelectric ceramic square plate of 700 μm length and 400 μm thickness. A lumped parameter model was used in the design procedure. The measured sensitivity of the prototype was −249.60 dB ref. One volt per micropascal without a preamplifier, and the measured resonant frequency was 30 kHz, which agreed with the prediction. The other is an endurance problem due to high hydrostatic pressure. To develop the endurance for the high hydrostatic pressure in deep-sea, PZT thickness mode and oil-backing on the diaphragm backside were proposed. The comparison of oil-backing and air-backing is to be presented as an evaluation of the endurance development. [Research supported by MRCnd.]
Surface wave testing of pavements.
Authors: Ryden Nils
Published: October 2013

Pavements are constructed using several layers of materials, and their durability depends on the quality of all of these strata. It is, therefore, valuable to be able to determine the properties of the layers nondestructively. A method is presented for evaluating the thickness and stiffness of multilayered pavement structures from guided waves measured at the surface. In this type of layered structure, the interaction of leaky Lamb waves in the embedded layers generates surface waves corresponding only to certain portions of the guided wave dispersion curves and branches measurable at the pavement surface. To resolve the different mode branches, the wavefield is measured at the surface by using a light hammer as the source and an accelerometer as receiver, generating a synthetic receiver array. The recorded data are transformed to a phase velocity spectrum, which is then inverted to give the layer properties using a global inversion algorithm. The theoretical background along with experimental results of the application to nondestructive testing of pavements will be presented. Ongoing research on noncontact air-coupled measurements is also demonstrated. This opens up the possibility for faster on-the-fly surface wave testing of pavement layers, since surface contact is no longer required.
Measurement of diffuse sound reflection from an impedance surfaces using one microphone by bayesian inversion.
Authors: Steininger Gavin , Hodgson Murray
Published: October 2013

This paper discusses the use of inverse methods to find the absorption and diffusion characteristics of surfaces. An impedance surface in an anechoic chamber is excited by a pure tone source above it. The steady-state sound level is measured at n points above the impedance surface. The distribution of the n steady-state sound-pressure levels is assumed to be Gaussian. The set of mean or predicted values for this distribution is generated by finding the modulus of a modified Sommerfeld boundary element solution to the Helmholtz equation. The modification is to add multiple diffusely reflected waves each of which is additionally attenuated by a distribution that is proportional to sin(2θ)×G(θ)Dθ×H(φ)Dφ, where G(θ) is the piecewise function [G(θ)=θ/θSpec, θ⩽θSpec, and [(π/2)−θ]/[(π/2)−θ]Spec otherwise] and H(φ)=|(1−φ)/π|. The system of equations is then optimized for the specific impedance of the surface, the normal diffusion coefficient, and the azimuth diffusion coefficient (Z, Dθ, and Dφ) using Bayesian inversion. This process is repeated for two surfaces (painted plywood over 16 inch studs and painted plywood over 16 inch studs with randomly placed wooden blocks) at six frequencies (250, 500, 1000, 2000, 4000, and 8000 Hz).
Bubble dynamics with tissue confinement in shock-wave lithotripsy.
Authors: Freund Jonathan B. , Shukla Ratnesh
Published: October 2013

Estimates are made of the effect of confinement by tissues on the action of small bubbles when subjected to strong pressure waves. The applications of interest are biomedical procedures involving short strong ultrasound bursts or weak shocks of the kind delivered in shock-wave lithotripsy. Confinement is anticipated to be important in suppressing mechanical injury and slowing the rate of its spread. We consider bubbles in a liquid such as blood within a small vessel in the tissue. A generalization of the Rayleigh–Plesset equation allows us to estimate the effect of the elasticity and viscosity of the surrounding tissue. Ranges of soft-tissue properties are estimated from a variety of different measurements available in literature. Solutions suggest that elasticity is insufficient to significantly alter bubble dynamics, but that viscosities from the mid-to-high range of those suggested might play a significant role in suppressing bubble action. Simulations in two space dimensions of a shocked bubble in a waterlike fluid interacting with a viscous material show that the much more complicated bubble jetting dynamics in this configuration is also significantly suppressed. The dynamics of this suppression is investigated.
Simulation of three–dimensional crack profiles in shock wave lithotripsy.
Authors: Wijerathne Maddegedara Lalith Lakshman , Sakaguchi Hide , Oguni Kenji , Hori Muneo
Published: October 2013

Some of the experiments reported by Xufeng Xi and Pei Zhong in 2001 were simulated to explore the sources of crack initiation and propagation in shock wave lithotripsy (SWL). An interesting result they reported was the T-shaped crack pattern in plaster of paris cylinders, subjected to transverse pressure pulses. This nontrivial crack pattern and some others were simulated, in 3-D, using a numerical technique called PDS-FEM. According to this 3-D simulations, it was found that the interference of reflected and focused high pressure pulse, by the distal surface, and the lagging low tensile phase created high tensile regions in the cylindrical sample. These high stress regions initiate and drive two horizontal and vertical cracks leading to the T-shaped crack. Due to the lack of data, a typical lithotripter pressure wave profile and material properties for plaster of paris were used. The observed crack patterns were successfully regenerated in 3-D, irrespective of these approximations. The distances between the vertical crack and the distal face for the crack patterns of the experiments and numerical simulations are nearly 0.34×d and 0.35×d, respectively (d=diameter). This quantitative comparison shows the potential applications of PDS-FEM for exploring and further development of SWL technology.
Shock wave interaction with cavitation bubble clusters generated in lithotripsy.
Authors: Thomas Derek C. , Hay Todd A. , Hamilton Mark F.
Published: October 2013

Collapse of cavitation bubbles generated in shock wave lithotripsy is essential to the comminution of kidney stones. After passage of the shock, however, if insufficient time has elapsed for the bubbles to dissolve, acoustic scattering from residual bubbles shields the stone from the next shock. Therefore, cavitation also limits the maximum firing rate. As important as collective bubble dynamics are to the efficacy of shock wave lithotripsy, behavior of the bubble clusters is among the least understood physical processes involved. A model was developed previously for the pulsation and translation of dynamically coupled spherical gas bubbles [Ilinskii et al., J. Acoust. Soc. Am. 121, 786 (2007)]. This model was augmented to account for interaction with the focused shock wave incident on the cluster at the order of the Born approximation. Diffraction of the shock wave is described by the KZK equation. The model predicts translation and coalescence of the bubbles due to transmission of the shock through the cluster. Predicted also is the acoustic wave scattered from the cluster, which in the forward direction is the leading order effect of the cluster on the transmitted shock wave. [Work supported by the ARL McKinney Fellowship in Acoustics and NIH DK070618.]
Shock wave lithotripsy can alter urinary acid-base pH regulation.
Authors: Handa Rajash K. , Connors Bret A. , Johnson Cynthia D. , Evan Andrew P. , Goel Mahesh C. , Lingeman James E. , Worcester Elaine M. , Coe Fredric L.
Published: October 2013

The renal papilla is particularly susceptible to injury by shock waves (SWs). Since the papilla is vital for urinary pH regulation, we hypothesized that shock wave lithotripsy (SWL)-induced damage of papillae will alter the pH of the urine. Experiments were conducted in four female adult Gottingen minipigs. The HM3 lithotripter delivered a total of 8000 SWs (24 kV, 120 SWs/min) among all papillae of one kidney, while the untreated, opposite kidney was used as control. The pigs were allowed to recover and 5 weeks later they were anesthetized. Serial urine collections were obtained from the SW-treated and untreated kidney. Urine was collected under mineral oil and immediately tested for its pH. Both kidneys were then perfusion fixed for histological analysis. Urinary pH was 0.17 units greater (P<0.05) in the SW-treated kidney compared to the untreated kidney. Histology showed scarring in all regions of the SW-treated kidney, with thick ascending limbs and collecting ducts having grossly abnormal morphologies indicative of cellular proliferation. These results suggest that SWL-induced injury can cause remodeling of nephron structures and long-term impairment in the regulation of urinary pH.
Ellipsoidal-reflector high intensity focused ultrasound system with integrated safety monitoring.
Authors: Samuels Joshua , Zderic Vesna
Published: October 2013

High intensity focused ultrasound (HIFU) transducers can be created using concave piezo elements, acoustic lenses, phased arrays, or ellipsoidal reflectors. By using a 2 MHz cylindrical piezoelectric crystal and a brass ellipsoidal reflector, it was possible to use the base of the transducer to house specific devices which can be integrated into a safety system for the device. This system assists in focal point positioning, ablation confirmation, as well as assuring proper flow of coolant through the attached water pillow to couple the device. These methods combine to protect the patient and the device itself from improper use or dangerous positioning of the focal point within the tissue. The proposed system utilizes an unfocused 3.5 MHz ultrasound transducer to act as a rangefinder, determining the distance of the tissue from the transducer. A simple graphical user interface allows the maximum allowed depth of ablation to be user defined and a warning displayed if needed. A water pillow with integrated flow meter is used to provide cooling and coupling to the tissue. There is also a housed video camera in the device which could provide visual confirmation of ablation if used laparoscopically or for superficial lesions.
Ocean acoustic noise budgets: Application to the environmental assessment of offshore wind power generation.
Authors: Miller James H. , Potty Gopu R. , Nunez Perez Andres , Vigness Raposa Kathleen , Nystuen Jeffrey A.
Published: October 2013

A noise budget is a listing of the various sources of acoustic noise and their associated ranking by importance. A number of different types of budgets can be conceived using various acoustic measures such as intensity, energy, or duration of maximum amplitude level. These budgets are typically parameterized by frequency and are usually computed over 1/3 octave bands. As part of the environmental assessment of the proposed offshore wind power generation project under the Rhode Island Special Area Management Plan (SAMP), noise measurements were made using the Passive Acoustic Listener (PAL) systems off the coast of Rhode Island prior to the installation of any wind power facilities. Two PALs were deployed within two miles of Block Island in water depths of 20 m from October 6 to November 11, 2008. The data included noise spectra and source identification every 3 min. Short snapshots of unusual sounds were also recorded. From this data, the ocean acoustic noise budget is computed with contributions from shipping, wind/waves, marine mammals, and rain from 500 Hz to 50 kHz. The ship noise data is correlated with ship traffic data from the Automatic Identification System (AIS). [Funding provided by the Rhode Island Office of Energy Resources.]
Why we have two ears—a hands-on experiment comparing monaural and binaural hearing.
Authors: Muehleisen Ralph T.
Published: October 2013

Whether they fly, swim, crawl, or walk, vertebrates have binaural auditory systems. Two ears provide redundancy in case of injury to the auditory system, improve the ability to detect quiet sounds and, perhaps most importantly, improve the ability to localize sound. This paper describes a simple experiment in which two individuals work together to investigate the sound localizing abilities of a human using monaural and binaural hearing. In the experiment, one person sits blindfolded in the center of a circle and acts as a listener. The other person moves a sound source around a circle, equidistant from the listener while the listener attempts to locate the direction of the source. The experiment is repeated for both monaural (with an earplug in one ear) and binaural (using both ears) hearing and for impulsive and low frequency tonal sources. The experiment is best attempted in an environment with very few nearby reflecting sources such as the outdoors or a very large room.
A simple analytical demonstration of transient and steady-state response in a dissipative closed waveguide based on the d’Alembert solution.
Authors: Ginsberg Jerry H.
Published: October 2013

Previously [J. H. Ginsberg, J. Acoust. Soc. Am. 119, 1954–1960 (2006)], the d’Alembert solution of the wave equation was adapted to address the response to initial conditions of a one-dimensional waveguide whose terminations have an arbitrary real (possibly dissipative) impedance. The technique creates virtual images on the other (i.e., nonphysical) side of each wall to convert the closed waveguide to one of infinite extent. The present work extends the development to cases where an arbitrary velocity is applied to one wall. The imaging technique allows one to visually track the evolution of the spatial pressure profile and the relation of temporal waveforms at various locations. The relatively low level of mathematical skills entailed in the formulation makes the method accessible to students at all levels. Application of the technique to periodic excitation of the boundary leads to visual representation of various effects, including reverberation time and various resonance effects, such as uncontrolled growth in the absence of dissipation and approach to steady-state when dissipation is present. Sound files generated from the synthesized connect the physical and audible phenomena.
Modal analysis for undergraduate laboratories and projects.
Authors: Kotlicki Andrzej , Waltham Chris
Published: October 2013

Vibrational analysis of structures (musical instruments for example) requires a means of excitation, motion detection and a data acquisition system. None of these needs to be very expensive. We have constructed an impact hammer using a piezoelectric crystal from an old barbeque lighter; this provides rapid excitation at all frequencies up to 1 or 2 kHz. Motion detection is now possible using extremely light (less than 1 g) microelectromechnical systems (MEMS) accelerometers that cost only a few dollars each. Two-channel data acquisition at 44.1kHz per channel is available to anyone with a computer equipped with a soundcard. More flexible external systems are also available in the $200 range. Thus, modal analysis is easily within the budgets of undergraduate laboratories. In this presentation we will emphasize the calibration of the impact hammer and evaluation of the MEMS accelerometers.
Minneapolis et al versus the Metropolitan Airports Commission.
Authors: Schomer Paul
Published: October 2013

The city of Minneapolis has a law protecting the quietude in various land use areas, including residential areas. In this legal action, plaintiff asserted that the Metropolitan Airports Commission was adversely and significantly affecting the quietude of the residents in the 60–65 DNL zone and that a 5-dB noise insulation package in homes in that zone would ameliorate the situation. There were four tasks for plaintiff’s expert witnesses; (1) Define quietude; (2) Show that without the airport quietude existed in the 60–65 DNL zone; (3) Quantify the impacts including annoyance, speech interference, and sleep disturbance; and (4) Quantify the benefits of a 5-dB noise insulation package. The results were a negotiated settlement for $128 million.