bluuebunny/crossref_metadata_2025 huggingface dataset:
Production and perception of Taiwan Mandarin syllable contraction.
Authors: Kuo Grace Chen-Hsiu
Published: March 2010

Taiwan Mandarin syllable contraction is an optional lenition process which involves the elision of the intervocalic segments and the merger of the tonal elements of two syllables. Here it is shown that syllable contraction is gradient and non-neutralizing. In a production experiment, 20 subjects read a list of minimal sentence pairs, containing disyllabic contractable words and matched monosyllabic lexical words, at two speech rates (88 and 144 beats/min), three times each. Degree of contraction was measured as the depth of the intensity trough between two syllables [Mermelstein 1975], with a trough depth (TrD) of zero meaning fully contracted. 8% of disyllables were somewhat contracted (TrD between 0 and 2 dB) while 29% were fully contracted (TrD = 0 dB). Fully contracted disyllables were compared on several other acoustic measures to their monosyllabic counterparts and were found to differ most strongly in duration. In a perception experiment, items from the production experiment were presented to 35 listeners for forced-choice identification as disyllabic or monosyllabic words. Accuracy was generally high; reaction times were slower for lexical monosyllables, which were sometimes labeled as contracted. Thus, even when fully contracted syllables were produced, they remained acoustically and perceptually distinct from monosyllables.
Prosodic perception and production of English- and Chinese-native speakers.
Authors: Rodriguez Amanda , Liu Chang
Published: March 2010

Our previous studies have shown that English-native adult speakers demonstrated categorical perception in tonal identification of speech and nonspeech sounds as typically as Chinese-native adult speakers. The purpose of this study was to investigate whether prosodic perception of English speech sounds was different between English- and Chinese-native listeners. F0 contour was manipulated from falling to rising patterns for the target word embedded in a short sentence. Listener’s task was to identify the prosody of each sentence, either question or statement. Preliminary results suggested that both groups of listeners showed typical categorical perception, while the two groups had significant difference in categorical boundary. The difference in categorical boundary for prosodic perception between the two groups of listeners was similar to our previous findings in tonal perception, likely due to the difference in the listener’s language background. English sentences with statement and question will be recorded for the two groups of listeners. The relationship between prosodic perception and perception will be discussed. [Work supported by The University of Texas at Austin, Undergraduate Research Fellowship.]
Influence of perceptual training of syllable codas for English consonants on sentences.
Authors: Lopez-Soto Teresa , Kewley-Port Diane
Published: March 2010

This study extends our previous report suggesting that moderate amounts of speech perception training were associated with improved speech production. This study also examined perception in sentences. A new group of 8 Spanish speakers (<10 year residence in US) trained on 13 English final consonants in syllables using SPATS software. On days 1 and 7 the group participated in perception and production tasks with the 13 codas (pre- and post-tests). Perception tests included coda identification in both syllable stimuli and in 18 sentences extracted from the IEEE corpus (90 keywords). Results showed the following. (1)With 5-h training of the 13 codas in syllable stimuli, perception improved significantly (>10%) in the syllable post-test, with smaller improvement in the sentence post-test (>7%). (2) Although average improvement was small for codas tested in sentences, several improved substantially (>20%), while a few decreased considerably after perception training. (3) Absolute values in both post-tests show similar performance, near 90%, although interesting differences for specific consonants were noted. The results showed that perception of sounds when measured in different linguistic contexts (syllables versus sentences) rendered different results. The study lays ground for investigating how cross-language perception of individual sounds is influenced by the phonetic context.
The production and perception of English consonant sequences by Japanese-speaking learners of English.
Authors: Sperbeck Mieko , Strange Winifred
Published: March 2010

This study reports the second part of a study investigating vowel insertion phenomena among Japanese speakers. A previous study [Sperbeck (2009)] that measured categorial discrimination demonstrated that some contrastive CCV versus CəCV sequences were hard for Japanese listeners (72% correct overall). The current study explored difficulties in production and how production correlated with perception. Nonsense words were constructed as the stimuli. They were of the form/CC(C)ani/ and /CəC(C)ani/, where CC(C) combinations were /sp, sk, pl, kl, bl, gl, spl, skl/. A delayed imitation task was used to assess production. Participants heard a native speaker’s productions (e.g., Say blani now) twice, produced the target word in isolation (e.g., blani), and then produced it in the carrier sentence (e.g., I said blani now). The latter was scored in this study. Two phonetically trained native English speakers perceptually transcribed the productions. Results showed that the overall percent correct was 66% (SE = 3.17) among Japanese speakers. There was a significant correlation between perception and production performance (rho = + 0.715. p<0.01). However, the major error type was vowel deletion, rather than vowel epenthesis in producing the CəCV tokens. The relationship between perception and production among L2 learners will be discussed.
Discrimination and identification of synthetic [da]-[ga] sounds by adults and children 4–6 years of age.
Authors: Richardson Kelly , Sussman Joan
Published: March 2010

Identification of sounds along the alveolar-to-velar contrast has been shown to be different for children born with clefts of the palate compared to other children [e.g., Whitehill et al. (2003)]. However, little information concerning discrimination abilities of children, in general, is known. The current study used a seven-step continuum of synthetic consonant-vowel syllables changing from “da” to “ga” by the 40 ms third formant frequency transitions [Sensimetrics Corporation (1995)]. Each listener heard 180 trials of a “change no-change” discrimination paradigm with two, three, four, and six-step comparisons to the endpoint, stimulus number 1 “da.” Listeners were asked to verbally respond as to whether there was a “change” or “no-change” in the sounds presented. Results revealed that as the stimulus contrast increased, adults became better at discriminating the comparisons, whereas children’s performance remained poor for all comparisons. Adults also showed less variability in their responses as the contrasts grew larger. In the identification task, young children displayed a much smaller velar category compared to the adult group. Furthermore, children were significantly poorer than adults at identifying the endpoint stimuli, as well as within-category exemplars. Results are compared to perception of other places of articulation by children and adults.
Lexical recognition memory across dialects.
Authors: Clopper Cynthia G. , Tamati Terrin N.
Published: March 2010

Implicit recognition memory for spoken words is more accurate when words are repeated by the same or a similar talker than when they are repeated by a different talker. The current study explored implicit recognition memory for words repeated by the same talker, by a different talker from the same dialect, and by a different talker from a different dialect in a word recognition task in noise. Repetitions produced by the same talker facilitated word recognition performance. However, for target words originally produced by talkers from the Northern dialect of American English, repetitions produced by a talker from the Midland dialect of American English inhibited word recognition performance. No repetition effect was observed for repetitions produced by a different talker from the same dialect or for words repeated by Northern talkers that were originally produced by Midland talkers. These results suggest an asymmetry in how indexical information is stored and activated in lexical processing. The same talker repetition effect was observed for both dialects, but one variety (the Northern dialect of American English) inhibited the repetition effect across dialects and the other variety (the Midland dialect of American English) did not.
The perceptual acquisition of Korean fricatives by first language Mandarin listeners.
Authors: Holliday Jeffrey J.
Published: March 2010

Despite numerous studies, it remains unclear how naive “foreign language” listeners become proficient L2 listeners, particularly in regard to difficult L2 contrasts. In an earlier study in which nine English-speaking L2 learners of Korean of varying proficiency and history of exposure to Korean identified Korean tense /s*/ versus non-tense /s/, listeners showed varying perceptual strategies. The results suggested that learners gradually learn to perceive differences in L2 contrasts by re-weighting useful cues and learning to ignore the “inefficient” cues that are initially relied on when the members of the L2 contrast are assimilated to L1 categories. This paper will report on the results of the same task (identification of CV sequences excised from real words), testing 30 L1 Mandarin speakers who have been in an intensive Korean language program in Seoul for about 2 months. The results of the present study will show whether there are as many inter-listener differences when the level and type of L2 exposure are much more controlled. In addition, because the acoustic cues relevant to the Mandarin sibilant fricative distinctions differ from those used in English the results will show to what extent the choice of perceptual strategy depends on acoustic properties of L1 contrasts.
Learning and generalization of novel contrasts across speakers.
Authors: Moon Kyuwon , Sumner Meghan
Published: March 2010

This paper examines how listeners use a learned contrast when encountering novel speakers. Do speakers reset to their native perceptual biases or apply a learned contrast to new speakers? In two experiments, participants took a minimal pair decision pre-test (MPD), a training session in which a native Korean speaker contrasts stop release (e.g., [bEt] = BET, [bEt’] = BED) without any V/C duration differences, a post-test (identical to pre-test), and a generalization-test [identical to pre-test, but with a speaker of a different L1 (Arabic)]. In Experiment 1, the only difference between the post-test and gen-test was the L1 of the speakers. We found that a learned phonetic contrast generalizes across speakers of different L1s with equally strong effects for post-test and generalization-test independent of order of presentation. In Experiment 2, the post-test was identical to that in Experiment 1, but the learned contrast was paired with vowel durations consistent with native English. Listeners were slower and less accurate in both the generalization-test and post-test when the generalization-test was presented before the post-test. The resulting asymmetry between the two experiments suggests that listeners use learned contrasts, but quickly reset to native patterns when native cues are present.
Bayesian geoacoustic inversion.
Authors: Dosso Stan E. , Dettmer Jan
Published: March 2010

This paper describes a general Bayesian approach to estimating seabed geoacoustic parameters from ocean acoustic data, which is also applicable to other inverse problems. Within a Bayesian formulation, the complete solution is given by the posterior probability density (PPD), which includes both data and prior information. Properties of the PPD, such as optimal parameter estimates, variances/covariances, correlations, and marginal probability distributions, are computed numerically for nonlinear problems using Markov-chain Monte Carlo methods. However, in many practical cases, both an appropriate model parametrization and the data error distribution are unknown and must be estimated as part of the inversion. These problems are linked, since the resolving power of the data is affected by the data uncertainties. Model selection is carried out by evaluating Bayesian evidence (parametrization likelihood given the data), or a point estimate thereof such as the Bayesian information criterion, which provides the simplest parametrization consistent with the data. The error covariance matrix (including off-diagonal terms, as needed) is estimated from residual analysis under the assumption of a simple, physically reasonable distribution form, such as a Gaussian or Laplace distribution. The validity of the above assumptions and estimates is examined a posteriori using both qualitative and quantitative statistical tests.
Sequential Bayesian strategies in geoacoustic inverse problems.
Authors: Dettmer Jan , Dosso Stan E. , Holland Charles W.
Published: March 2010

This paper considers sequential Bayesian strategies for geoacoustic inverse problems which are difficult to solve simultaneously due to computational constraints. Bayesian inference provides a powerful approach to learning problems such as this since sequential inversions of multiple data sets [with the posterior probability density (PPD) of one inversion applied as prior information in the subsequent inversion] are equivalent to simultaneous inversion of all data. However, passing PPDs forward as priors has its own challenges when the PPD is sampled numerically for nonlinear inverse problems, particularly when the model parameter space is of high dimensionality and the data information content is high. In such cases, approximations are required to efficiently carry PPD information forward to subsequent inversions. The approach developed here represents numerically sampled PPDs in terms of discretized marginal probability distributions for principal components of the parameters, which minimizes the loss of information in representing inter-parameter correlations. The sequential Bayesian approach is applied to seabed reflectivity inversion with multiple data sets representing travel-time data and frequency-domain reflection coefficient data for a series of increasing penetration depths. Data information content is quantified by accounting for potential error biases as well as data error covariances. [Work supported by the Office of Naval Research.]
Computation of normalizing constants in geoacoustic Bayesian inference.
Authors: Dettmer Jan , Dosso Stan E.
Published: March 2010

This paper considers approaches to computing normalizing constants (Z) in Bayesian inference problems. Bayes’ theorem combines the likelihood function, model prior, and Z to form the posterior probability density (PPD). Z (also known as evidence) is difficult to compute for general problems and a common approach is to avoid its computation entirely by calculating an unnormalized estimate of the PPD which is sufficient for moment estimates. However, estimating the normalized PPD, including Z, allows for moment estimates as well as quantifying the likelihood of the model parametrization. This is commonly referred to as model selection and poses a natural way to quantifying the most appropriate model parametrization for a given data set (Bayesian razor). Several approaches for computing Z have been developed in the statistics community, some of which are applied here to the geoacoustic inference problem. Annealed importance sampling follows an annealing approach and computes weighted averages along cooling trajectories. Nested sampling uses a likelihood constraint to move from the prior mass to the posterior. Both methods also give parameter estimates which are compared to Metropolis–Hastings results. [Work supported by the Office of Naval Research.]
Dependence of the structure of the shallow convergence zone on deep ocean bathymetry.
Authors: Lynch Stephen D. , D’Spain Gerald L. , Heaney Kevin , Baggeroer Arthur B. , Worcester Peter , Mercer James
Published: March 2010

During an experiment in the northern Philippine Sea in 2009, low-frequency tones were transmitted from a shallow (15- and 60-m) source deployed from R/V Melville keeping station to a shallow (250-m) horizontal receiver array towed by R/V Kilo Moana approximately one convergence zone (CZ) away. Recordings were made during events in which the receiver ship maintained constant range in the convergence zone and during events in which the receiver ship transited radially through the CZ. The shallow CZ exhibits strong dependence on the bathymetry mid-way between the source and receiver array. In fact, the variability of the structure of the first CZ in this environment is significantly more strongly affected by the heterogeneous character of the bottom than water column fluctuations. Numerical modeling with a parabolic equation code is used to support the conclusions from the data analysis.
Two dimensional finite element propagation and reverberation modeling in shallow water waveguides.
Authors: Isakson Marcia J.
Published: March 2010

Finite element propagation models do not rely on approximations of the scattering at the interfaces and therefore provide excellent benchmark solutions to rough interface waveguide propagation and reverberation studies. In this study, two dimensional finite element solutions for reverberation and propagation are calculated for waveguides that have rough interfaces at the air/water boundary and the water/sediment boundary. The effects of upward and downward refracting sound speed profiles are also considered. [Work sponsored by Office of Naval Research, Ocean Acoustics.]
Three-dimensional scattering from pressure-release rough surfaces.
Authors: Joshi Sumedh M. , Isakson Marcia J.
Published: March 2010

In order to compare a variety of three-dimensional (3-D) rough surface scattering theories, the scattering of a spherical wave incident on a pressure-release rough surface is modeled. Random surface realizations are computed from a spatial roughness power spectrum measured as part of the EVA sea test conducted in 2006. Scattering from these surfaces is computed using boundary and finite element methods. A singularity removal technique is applied to solve the Helmholtz–Kirchhoff boundary integral equation in 3-D. This integral solution is compared with 3-D finite elements and the 3-D Kirchhoff approximation, to determine the range of validity of the models.
Boundary roughness and the effect of internal waves on signal coherence for shallow water transmission.
Authors: DeFerrari Harry, A.
Published: March 2010

Broadband acoustic propagation experiments at three shallow sites allow for comparison of coherency of individual surface-reflected bottom-reflected modes of propagation. There appears to be a dependence of the correlation parameters of times and length on frequency and mode number that cannot be attributed to internal waves alone and likely depends on bottom and surface roughness. At low frequencies, f<100 Hz, during periods of quiescence internal waves, all modes of propagation have equally long coherence parameters. The coherency decrease equally for all modes as internal wave activity increases. For higher frequencies, 200 Hz <f<1000 Hz, the coherence parameters depend on mode number, with the lower order modes always more coherent than successive higher order modes. At still higher frequencies, f>1000 Hz, identifiable modes are not always observed; instead there is a continuum of arriving pulse energy with very low coherency even with minimal internal waves. Apparently, the randomizing effect of internal waves depends on bottom and surface roughness and frequency. At low frequencies, the boundaries appear flat and internal waves have a minimal effect. At the highest frequencies, phase coherence is already degraded by boundary roughness so that the slightest of internal wave activity completely randomizes the signals.
Frequency dispersion of parametric array signal in shallow water.
Authors: Esipov Igor , Tarasov Sergey , Voronin Vasily , Popov Oleg
Published: March 2010

Results of experimental test of parametric array application for marine shallow water waveguide excitation by sweep frequency modulated signal are discussed. Parametrical sound signal is forming in shallow water environment, which is stimulated by intensity modulated high frequency power acoustical pump. As a result the end-fire parametric array is forming there, which excites sharp directional signal radiation at the modulation frequency. Such a low-frequency signal, generated in the virtual end-fire array by parametrical means, will propagate in shallow water waveguide independently from the pump radiation. Shallow water signal propagation obeys to waveguide dispersion. Sweep modulated signal compression is experimentally shown for single mode signal propagation in shallow water. Acoustical signal of 2-ms duration is generated in frequency band of 7–15 kHz by parametric array. This signal is transmitted in single lobe of 2 deg width along the path of 5.6 km long in water layer from 2.5- to 3-m depth. The directivity of the signal transmitted was constant in the whole frequency range. It was shown the single mode excitation of the shallow water waveguide takes place under this circumstance. [Work supported by ISTC, Project No. 3770.]
Measuring and defining the sound quality of audio systems.
Authors: Mapp Peter
Published: March 2010

“High quality” is a term often employed as a requirement for the performance of an audio or sound system, yet what does it mean and can it be quantified? In particular, bass performance is an important aspect but again is extremely hard to define. Frequency response assessment alone is not enough to characterize sound quality as this does not provide information with regard to the temporal or transient characteristics of the room or system. The paper will look at a number of techniques that potentially can be used to help assess sound system performance including a new measurement method intended to quantify the transient and temporal characteristic of the bass sound in a room, whether this is via a sound system or an assessment of the room itself.
Sweetness spotting.
Authors: Ortallono Sam
Published: March 2010

This paper investigates the traditional listening position for the mixing of stereo music in a near field-monitoring situation. Common sense and current practice reinforce the ideal listening post to be at the apex of an equilateral triangle formed by the two speakers and the observer’s head. This experiment will put that notion to the test. Using white noise pink noise, sine waves, and program material we will compare listening positions to the left and right as well as closer and farther. Readings from several mixing studios at multiple facilities will provide the numbers. Results will be correlated with room size, shape, and room treatment. Will the data uphold the longstanding wisdom on phase coherency and stereo image or will the results surprise us all?
How reverberation degrades and aids source perception in auditory scenes.
Authors: Shinn-Cunningham Barbara G.
Published: March 2010

Reverberant energy (or reverberation) influences perception of source content (in addition to influencing perception of the environment and of source location). Moreover, reverberation can affect perception in different ways depending on whether a source is played in quiet or in a scene containing competing sounds. Reverberation smears spectro-temporal structure, which can interfere with estimation of duration, pitch contour, and other basic attributes. In the extreme, such spectro-temporal smearing (self-masking) can interfere with extracting the meaning of signals like speech or music. However, if the direct sound reaching a listener is nearly inaudible, reverberation adds energy, improving source detectability. While these in-quiet effects contribute to perception of sources in a complex acoustic scene, additional factors also come into play. For instance, if two otherwise similar sources have different levels of reverberation, the reverberation can make them more perceptually distinct, making it easier to focus attention on one and understand it. On the other hand, the same spectro-temporal smearing that can hurt perception of a source in quiet can also disrupt source segregation, making it difficult to selectively analyze a desired source. Examples of these different effects of reverberation on perception, taken from recent experiments, will be presented and discussed.
Acoustics in a home music listening room.
Authors: Beristain Sergio
Published: March 2010

A room was designed with the sole purpose of listen all kinds of recorded music, with a high preference to classical and romantic music. It was decided to locate the room in the basement level of a large single family home, where the external noise control or the control of the sound going out were not the big issues, so that the internal acoustics became the main one. The acoustics was adjusted for clear and balanced sound, and the high-end audio system to be installed can handle monophonic, stereophonic, and surround signals, but stereo sources are paramount. The room is 4 m wide, 7 m long, and 2.8 m high, with the lower part of the walls used for the equipment and music source storage, while the floor, ceiling, and higher part of the walls are the places where the non-proprietary acoustic materials and the speakers are going to be located.
Autonomous underwater glider based embedded real-time marine mammal detection and classification.
Authors: Olmstead Tyler J. , Roch Marie A. , Hursky Paul , Porter Michael B. , Klinck Holger , Mellinger David K. , Helble Tyler , Wiggins Sean S. , D’Spain Gerald L. , Hildebrand John A.
Published: March 2010

Autonomous marine vehicles offer the potential to provide low-cost data suitable for passive acoustic monitoring applications of marine mammals. Due to their extremely low-power consumption and long range, gliders are an attractive option for long-term deployments. Challenges related to power availability, payload size, and weight have previously restricted the viability of marine mammal monitoring. As an example, the wide bandwidth of odontocete echolocation clicks requires a high sampling rate and poses challenges with respect to limitations in power, size, and weight of the deployed system. Recent developments in commercial off-the-shelf hardware driven by the mobile phone industry’s need for multimedia-rich smart phones have resulted in low-power architectures capable of performing computationally demanding signal processing and stochastic recognition tasks in real time. We describe our work on a small form-factor, light-weight package used to perform real-time passive acoustic detection and classification. The system detects echolocation clicks using Teager energy. Echolocation clicks are then classified using cepstral features processed by a Gaussian mixture model. [Work sponsored by ONR.]
Analysis of cetacea vocalizations using ocean bottom seismic array observations, western Woodlark Basin, Papua New Guinea.
Authors: Frank Scott D. , Ferris Aaron N.
Published: March 2010

Over a 6-month period in 1999 an array of seven ocean bottom seismometers and seven bottom mounted hydrophones covered a 30-km2 area at 2–3-km water depth in the western Woodlark Basin. The array’s main task was the detection of microearthquakes associated with nearby active tectonics. However, it also made fortuitous broadband recordings of Cetacea vocalizations that we associate with finback whales. Each of these signals has a 10–15-s duration and they exhibit a repetitive pattern with 10–15-min period. The signals are well recorded across both the seismometers and hydrophones, which were sampled at 64 and 125 Hz, respectively. Time-varying spectral analysis demonstrates that the signals are frequency modulated in the 20–30-Hz band with most energy occurring at ∼22 Hz. We employ array-based methods (e.g., optimal beam forming techniques) and acoustic transmission loss simulations to determine range and bearing of the acoustic sources. Preliminary analysis indicates that the acoustic sources originate near the array, and secondary signals may represent back-scattered energy from the short-wavelength, high-topographic features associated the active tectonics with in the basin.
Miniaturization of insect-inspired acoustic sensors.
Authors: Ogam Erick , Ruffier Franck , Wirgin Armand , Oduor Andrew
Published: March 2010

Insects can navigate and follow sound sources with precision in complex environments using efficient principles based on particular and appropriate sensory-motor processing. It is precisely these principles, little understood at this point, that we want to understand, model, and validate by rebuilding them on a micro-flying device. To achieve this goal, a new bio-mimetic acoustic sensor inspired by the cricket’s auditory system has been developed and tested in an anechoic chamber. The performance of the processing algorithm, the aperture of the auditory system, and interferences caused by the geometry of the sensor itself were first evaluated: synthetic signals were generated by a boundary element model taking into account the three-dimensional geometry of the sensor to characterize its performance in free space. A processing based on cross-correlation for localizing and tracking an acoustic source was also studied to assess whether the observed limitations were inherent to the geometry of the sensor or due to limitations of the cricket inspired processing algorithm. The sensor worked well with several synthetic chirped cricket songs. [Work supported by CNRS PIR Neuroinformatique grant SonoBot.]
Three-dimensional finestructure and vertical microstructure in thermohaline intrusions.
Authors: Gregg Michael C. , Shcherbina Andrei Y. , Alford Matthew H. , Harcourt Ramsey R.
Published: March 2010

Thermohaline intrusions have intrigued physical oceanographers since the first XBT section was published by Spilhaus in 1939. Characterized by vertical gradients of temperature and salinity having compensating density effects, intrusions are meters to tens of meters thick and extend laterally for hundreds of meters to many kilometers. Boundaries often have TS staircases produced by salt fingering or diffusive layering. Large diapycnal fluxes have been inferred from sections showing intrusions sloping across isopycnals, but these inferences are questionable, as isopycnal movements can give the illusion of diapycnal motion. To address these issues, in 2007 we used a depth-cycling towed body, a neutrally buoyant Lagrangian float, and microstructure profilers to map and follow intrusions in the subtropical front north of Hawaii. All intrusions were connected to the front, i.e., none was isolated lenses, some as long, thin folds, and others resembled tongues. About 10 m thick, the sheets protruded 10 km into the warm, saline side of the front, were coherent laterally for 10–30 km, and lasted at least 1 week, evolving at both inertial (23 h) and sub-inertial (∼10 day) time scales. They appeared to be formed by advective deformation of the front driven by sub-mesoscale two-dimensional motions.
Internal waves, intrusions, and coastal zone acoustics.
Authors: Duda Timothy F. , Lavery Andone C. , Collis Jon M.
Published: March 2010

Ubiquitous linear internal waves are known to dominate fluctuations of long-range low-frequency sound in the deep ocean. In the coastal zone, however, variations in low-frequency-sound propagation caused by large episodic nonlinear internal waves are often dominant and have been studied in detail. Apart from this, sound-speed anomalies from smaller but pervasive linear internal waves can also influence propagation, as do density-compensated temperature/salinity intrusions found in areas near fronts. The physical nature of each of these two phenomena and existing models of their effects on propagation will be reviewed. The possibility of using high-frequency acoustics to remotely examine and map intrusions via double-diffusive microstructure scattering will also be examined. The anisotropy of the coastal internal wave field will be discussed, and subsequent acoustic propagation anisotropy will be examined using data from the multi-PI Shallow-Water 2006 experiment in the Mid-Atlantic Bight. [Research supported by the Office of Naval Research.]
Analysis of horizontal coherence during the transverse acoustic variability experiment.
Authors: Mignerey Peter C. , Goldstein David J.
Published: March 2010

The transverse acoustic variability experiment took place in the northern limit of the East China Sea in 65–80 m of water. 300-Hz and 500-Hz cw acoustic signals were transmitted over distances of 33 and 20 km to a broadside HLA where they were received at 22–27 dB SNR. Fourteen estimates of transverse mutual-coherence functions show high correlation with scale lengths on the order of 1000–1700 m. A towed CTD chain provided simultaneous measurements of the sound-speed fluctuation spectrum due to internal waves in an effort to determine whether the observed shallow-water coherence is understandable within the framework of a normal-mode formulation of path-integral theory. An important property of the mutual-coherence function is its behavior at small hydrophone separations. Here the phase-structure function is expected to follow a power law. Measured logarithmic phase-structure function have slopes that vary between 0.6 and 1.1, which disagree with path-integral solutions that predict slope 2. The discrepancy between observation and data is not currently understood. [Work supported by the Office of Naval Research.]
Effects of anisotropic internal waves on acoustic propagation within the East China Sea.
Authors: Smith Chad M. , Bradley David L.
Published: March 2010

Using environmental and acoustic data from the TAVEX 2008 Korean/U.S. cooperative experiment, the anisotropic spatial properties of internal waves recorded during CTD tows and their connection to temporal variations in recorded acoustic data from a horizontal line array will be discussed. Structure of internal waves, wave travel speed and trajectory, as well as computational modeling of the acoustic field and its comparison with recorded data will also be covered. [Work supported by the Office of Naval Research Contract No. N00014-08-1-0455.]
Adjoint study of water column variability and propagation in the transverse acoustic variability experiment (TAVEX 2008).
Authors: Kingsland Michelle M. , Bradley David L.
Published: March 2010

Internal wave and other water column activity in the conductivity, temperature, and depth (CTD) data collected in the East China Sea as a part of TAVEX 2008 are used as a basis for analyzing acoustic propagation at 500 Hz between a fixed source and fixed horizontal line array placed on the seafloor. Because the CTD data were not taken coincident with the acoustic propagation path (in general), adjoint modeling methods will be used to study acoustic data and prediction misfit. Usefulness of the adjoint method for these experimental conditions will be discussed. [Work supported by ONR.]
Acoustic propagation effects from saline intrusions across the shelfbreak front off the New Jersey coast in summer.
Authors: Newhall Arthur E. , Lin Ying-Tsong , Lynch James F. , Duda Timothy F. , Gawarkiewicz Glen G. , Colosi John A.
Published: March 2010

In the summer of 2006, the multi-task, interdisciplinary Shallow Water 2006 (SW06) experiment was conducted on the continental shelf and shelfbreak regions off the New Jersey coast. During SW06 the shelfbreak front variability was clearly characterized by combined measurements of conductivity-temperature-depth casts, long-period (5 weeks) and quick sampling oceanographic sensor moorings, and surveys with a Scanfish, a ship-towed undulating vehicle carrying multiple sensors. This data set indicates that the slope water penetrated onto the shelf via neutrally buoyant intrusions. Due to the higher temperature and salinity, these frontal intrusions, seen as thin layers near the seasonal pycnocline, increased the local sound speed and accounted for variations in acoustic propagation. In this paper, we will use field data and PE numerical acoustic simulations to study the impact of these frontal intrusions. Specific examples on the creation of vertical acoustic double ducting and horizontal ducting formed by these intrusions and their modulation by linear internal waves are discussed. [Work is supported by the Office of Naval Research.]
Applications of acoustic droplet vaporization in diagnostic and therapeutic ultrasound.
Authors: Fabiilli Mario L. , Kripfgans Oliver D. , Zhang Man , Haworth Kevin J. , Lo Andrea H. , Carson Paul L. , Fowlkes J. Brian
Published: March 2010

Micron- and nano-sized colloids are being studied in diagnostic and therapeutic applications of ultrasound (US). Unlike clinically utilized microbubbles, emulsions possess unique physiochemical properties that could translate into distinct, clinical benefits beyond conventional contrast agents. Droplets, composed of a superheated liquid, can be phase transitioned into bubbles using US, a process known as acoustic droplet vaporization (ADV). Droplets, transpulmonary in size, transition into bubbles upon ADV and can reach diameters that occlude capillaries and arrest blood flow in the vascular bed. Examples of ADV in diagnostic and therapeutic applications will be presented. First, ADV has been used in phase aberration correction in transcranial US imaging. Second, ADV-generated microbubbles can reduce and occlude renal perfusion in vivo. Third, the effects of thermal therapy using high-intensity focused ultrasound (HIFU) has been enhanced and controlled more effectively using ADV. Fourth, ADV has been utilized as a release mechanism for therapeutic agents that are incorporated into the emulsion. In all applications, the physiochemical properties of the droplets coupled with the spatial and temporal control afforded by ADV-generated microbubbles are crucial to the success of each ADV development. [This work was supported in part by NIH Grant 5R01EB000281.]
Bubble evolution in acoustic droplet vaporization.
Authors: Qamar Adnan , Wong Z. Z. , Fowlkes J. Brian , Bull Joseph L.
Published: March 2010

We present an overview of our recent theoretical and computational work on acoustic droplet vaporization within a confined tube and compare to our experimental data. This work is motivated by a developmental gas embolotherapy technique that involves injecting superheated transvascular liquid droplets and subsequently vaporizing the droplets with ultrasound to selectively form vascular microbubbles. The theoretical model describes the rapid phase transition from a superheated dodecafluoropentane (DDFP) droplet to the vapor phase via nucleation within the DDFP droplet. The theoretical results are compared to results from our computational models and high-speed camera experiments, and close agreement between the experimental bubble evolution and the prediction of the model is noted. Even though we consider bubbles that are small compared to the tube diameter, it is demonstrated that the tube affects the bubble evolution and resulting flow fields. [This work is supported by NIH Grant R01EB006476.]
Using optically activated nanoparticles to promote controlled lesion formation from high-intensity focused ultrasound exposures.
Authors: McLaughlan James R. , Murray Todd W. , Roy Ronald A.
Published: March 2010

The absorption of laser light in tissue can be enhanced through the use of gold nanoparticles. This enhancement can improve the signal-to-noise ratio of the thermoelastic emissions used for photoacoustic tomography (PAT) and photoacoustic microscopy (PAM). The ability to functionalize nanoparticles allows them to be used for the selective targeting and destruction of cancer cells through the formation of vapor bubbles. However, the laser fluence required to generate vapor bubbles from nanoparticles typically exceeds the maximum permissible exposure for in-vivo applications. In a previous study, it was found that the combination of laser light with high-intensity focused ultrasound (HIFU) significantly reduced the fluence and pressure thresholds for bubble formation. The presence of bubbles, or specifically inertial cavitation, in HIFU exposures is believed to locally enhance the heating, resulting in effective tissue ablation at lower HIFU intensities. Nanoparticle-doped tissue phantoms (polyacrylamide gels containing bovine serum albumin) were exposed to a continuous wave (5–30-s) 1.1-MHz HIFU field with and without pulsed laser light (532 nm, 1–10 Hz) to assess the potential for HIFU lesion enhancement from the controlled and repeatable generation of inertial cavitation. [Work supported by the Gordon Center for Subsurface Sensing and Imaging Systems, NSF ERC Award No. EEC-9986821.]
Bubble-boundary interactions relevant to medical ultrasound.
Authors: Kreider Wayne , Chen Hong , Bailey Michael R. , Brayman Andrew A. , Matula Thomas J.
Published: March 2010

Because bubble-vessel interactions have been implicated in vascular damage associated with medical ultrasound, such interactions remain a topic of interest. Recent photographs have shown that bubbles inertially oscillating in blood vessels tend to cause a vessel invagination (displacement toward the lumen) that exceeds the corresponding distention. To gain an understanding of such interactions, a Bernoulli-type equation was derived for conditions in which flow near a bubble is confined by a nearby planar boundary. This formulation assumes incompressible, inviscid flow within a locally cylindrical geometry between the bubble and boundary. Using spherical, radial bubble dynamics inferred from the aforementioned photographs, pressures generated by the bubble at the boundary were calculated. The assumed sphericity was based on observations of bubble collapses and jetting behaviors. In addition, the form of the equation was compared to that for unconfined flow around a spherical bubble. The main conclusion is that tensile stresses corresponding to vessel invagination will be asymmetrically larger than compressive stresses associated with vessel distention as the amplitude of oscillation increases and the distance between the bubble and boundary decreases. As such, these tensile stresses may be an important mechanism for vascular bioeffects. [Work supported by NIH Grants EB00350, DK43881, and DK070618.]
MEMS (microelectromechanical systems) microphone array on a chip.
Authors: Krause Joshua S. , White Robert D.
Published: March 2010

The design, fabrication, and characterization of a surface micro-machined, front-vented, 64 channel (8×8), capacitively sensed microphone array-on-a-chip are described. The element pitch is 1.3-mm center-to-center and is targeted at resolving the high-wavenumber components of the pressure spectra underneath the turbulent boundary layer. Care is taken to minimize package topology to reduce flow generated self-noise. The array was fabricated using the MEMSCAP PolyMUMPs® process, a three layer polysilicon surface micromachining process, with the addition of a Parylene-C coating in post-processing. An acoustic lumped element model, including mechanical components, environmental loading, fluid damping, and other acoustic elements, is detailed. Laboratory calibration indicates a sensitivity of 1 mV/Pa for each microphone over a 200–40 000 Hz band. A strong resonance occurs at 280 kHz in close accordance with modeled results. Spatial mapping of the array reveals minimal electrical and physical cross-talk between elements. Preliminary element-to-element sensitivity comparisons exhibit a standard deviation of 13%, 12%, and 25% at 250 Hz, 500 Hz, and 1 kHz. Phase matching showed a 9, 10, and 15 deg standard deviation difference at the same frequencies. A more in depth analysis of acoustic sensitivity is ongoing as well as element-to-element variability.
Characterization of a high-frequency pressure-field calibration method.
Authors: Alexander Dylan , Barnard Casey , Griffin Benjamin A. , Sheplak Mark
Published: March 2010

A method for the direct measurement of the pressure sensitivity of a microelectromechanical system (MEMS) microphone is developed for frequencies from 10 to 100 kHz. The use of a simultaneous pressure field measurement reduces the errors in calculating the pressure sensitivity from free field measurements, and it allows calibration of non-reciprocal and non-capacitive transduction schemes. An ionophone is used as a calibration source in an anechoic chamber. An aluminum plate is mounted in the anechoic chamber and contains a linear array of pressure field condenser microphones. Treatment of the plate edge is used to minimize diffraction within the pressure field. The microphone data are used to characterize the directivity of the ionophone and localize sources of acoustic diffraction that could impact future MEMS microphone magnitude and phase calibrations.
Comprehensive development of the theory of nonuniformly spaced arrays.
Authors: Au Jenny Y. , Thompson Charles
Published: March 2010

In this work, we will present the work of comprehensive development of the theory of nonuniformly spaced arrays. It will be shown that the position may be determined in terms of the Fourier transform of the objective function. Special consideration will be given to the objective function of G. J. van der Maas in 1954. These results will be compared with that presented by Wallace in 1982.
The Acoustical Society of America and the Human Rights Coalition: An introduction.
Authors: Walsh Edward J.
Published: March 2010

Technological developments in recent years have significantly improved the capacity of human rights advocates to monitor and document abuses of authority, including violations of human rights at home and in remote isolated regions of the world. Recognizing the need for a platform from which scientists and scientific Societies might speak with a common voice to promote human rights protect the professional and personal interests of threatened colleagues, cooperate with human rights organizations, and press for the practical implementation of the right of all persons to the benefits of scientific progress and its applications, the AAAS Science and Human Rights Coalition was launched in 2008. Operating through the Panel on Public Policy, the ASA accepted an invitation to participate as an affiliate member of the Coalition, and the purpose of the Special Session is to introduce the membership at large to the principles and goals of the organization and to offer insight into the mechanism of operation and cooperation through which an effective interface between the scientific and human rights communities might be developed.
Novel exploration of the vibration of the Caribbean steelpan in response to authentic excitation.
Authors: O’Malley Patrick , Vignola Joseph F. , Judge John A.
Published: March 2010

A novel conformal scanning laser vibrometer was used to determine the vibrational modes of a C-lead tenor steelpan. The measurements provide a rich mechanical snapshot of the artistry involved in the marriage of metallurgy and music theory that goes into the creation of the instrument. The data represent the surface-normal motion of the entire face of the instrument in response to an impulsive excitation intended to mimic the strike of a mallet. A traditional scanning laser Doppler vibrometer is limited to measurement of planar geometries and therefore is of limited utility on the highly contoured surface of the steelpan. A description of the novel measurement system is presented, followed by the surface velocity data and a summary of response shapes and the frequencies at which those responses occur. The data show that individual note areas respond when adjacent or non-adjacent musically related notes are struck and clearly illustrate the complex vibration of the steelpan and the coupling between notes that produce the rich distinctive nature of the steelpan sound.