bluuebunny/crossref_metadata_2025 huggingface dataset:
Marine gas hydrate: Fabric, quantification and free gas content. Examples from Hydrate Ridge–Cascadia margin
Authors: Abegg Friedrich , Freitag Johannes , Bohrmann Gerhard
Published: October 2013

A recent advance in the investigation of internal gas hydrate structure and in small scale quantification is based on a combination of a new coring device and computerized x-ray tomography (CT). This approach has been chosen because gas hydrate is only stable within a special (low) temperature and (high) pressure field. A MultiAutoclaveCorer, developed by the Technical University of Berlin, is in principle similar to a piston corer and has the size of a multiple corer. During the deployments on Hydrate Ridge, two pressure vessels filled with seafloor samples could be recovered. They were CT-investigated after the cruise in a medical clinic close to San Francisco. As a result, a 3-D-dataset of the cores is available which allows to quantify the components’ gas hydrate, sediment and free gas and also shows the distribution and orientation of the gas bubbles. One of the pressure vessels showed a distinct gas hydrate horizon where the gas hydrate content reached close to 50 vol%. Within this horizon there was a free gas content of 2.4 vol%. The preferential bubble orientation, compared to free gas in soft marine sediments, is horizontal, not vertical, which is an indicator for the mechanism of gas hydrate formation.
Data-model comparisons for scattering by a bubbly sediment
Authors: Jackson Darrell R. , Tang Dajun
Published: October 2013

As part of the Coastal Benthic Boundary Layer Program, seafloor backscattering measurements were made at 40 kHz in Eckernfoerde Bay, Germany, in areas of high concentration of gaseous methane. Although it had long been known that methane bubbles have a profound influence on acoustic scattering, this was the first time that contemporaneous measurements were made of acoustic scattering and bubble size distributions. The latter measurements were part of a collaboration between Aubrey Anderson’s group and NRL-SSC and made detailed model-data comparisons possible. Acoustic interferometry was used to conclude that the dominant scattering layer was about 1 m below the sediment–water interface. A single scattering model accounted for the angular dependence and level of scattering, however, the model gave unphysical results at very small grazing angles. A multiple scattering model has been developed to remedy this defect. [Work sponsored by ONR.]
A review of theoretical models for microbubble contrast agents
Authors: Church Charles C. , Yang Xinmai
Published: October 2013

Theoretical investigation of the acoustic responses of albumin-encapsulated microspheres began nearly fifteen years ago when Albunex, the first agent approved for clinical use in the U.S., was still in development. Since that time, the number of potential ultrasound contrast agents has grown considerably. These agents utilize a variety of both shell materials (e.g., proteins, synthetic polymers, surfactants, lipids) and encapsulated gases (e.g., air, sulfur hexafluoride, perfluorocarbons). The shell may be very thick or vanishingly thin. A thorough understanding of the interaction between ultrasound pulses and contrast microbubbles is essential for the successful clinical application of a particular agent. In this talk, models developed by de Jong et al., Church, Ye, Allen et al., Khismatullin et al., and others will be reviewed. The basis of these theories is a free bubble model supplemented by the effect of the encapsulating shell. The differences among these models lie primarily in their treatment of the encapsulating layer and, to some extent, the surrounding medium. The nature of various contrast agents will be discussed, and appropriate models for each will be described. Comparisons among models will include predictions of clinically significant acoustic responses (resonance frequency, scattering strength, nonlinearity, etc.).
Acoustical correction to the bubble dynamics equation for elastic media
Authors: Emelianov Stanislav Y. , Hamilton Mark F. , Ilinskii Yurii A. , Meegan G. Douglas , Zabolotskaya Evgenia A.
Published: October 2013

Nonlinear oscillations of microbubbles are being investigated extensively for innovative medical and industrial applications. The Rayleigh–Plesset equation successfully describes the dynamics of gas bubbles in liquids and viscoelastic media. To model bubble dynamics in weakly compressible elastic media such as soft tissue, effects of shear stress should be taken into account. These effects were included recently by the authors in a model for bubble oscillations that differs from the Rayleigh–Plesset equation by a single term associated with nonlinear elasticity of the medium surrounding the bubble. Here, we augment this dynamical equation to account for acoustic radiation and thus describe nonlinear bubble oscillations in slightly compressible elastic media. The bubble is assumed to be spherical and the surrounding elastic medium to be isotropic. The analysis is performed in Eulerian coordinates, and attention is devoted to terms associated with radiation loss. Our analysis builds on results obtained by Prosperetti and Lezzi [J. Fluid Mech. 168, 457 (1986)] for a bubble in liquid. The stress tensor for the elastic medium is expressed through invariants of the Green deformation tensor in spherical coordinates. Explicit expressions for components of the stress tensor are obtained using Mooney’s potential function. [Work supported by IR&D at ARL:UT.]
Shear mode properties of single crystal ferroelectrics
Authors: McLaughlin E. A. , Robinson H. C.
Published: October 2013

Single crystal ferroelectrics or piezocrystals were recently introduced into the electroactive materials community. The 33-mode electromechanical coupling factor of piezocrystals is typically greater than 0.90, which is significantly larger than typical values for piezoelectric ceramics (0.62–0.74). For sonar projector applications this large k33 has been responsible for more than doubling the bandwidth of active sonar arrays over what is currently achievable with ceramics. Last year a crystal grower produced a cut of lead magnesium niobate-lead titanate (PMN-PT) single crystal with piezoelectric shear coefficient values of 7000 pm/V and shear coupling factors of 0.97. (For PZT5H, d15 is 730 pm/V.) This piezocrystal d15 coefficient implies significantly improved sensitivity and signal-to-noise ratio for accelerometers and hydrophones, while the high coupling promises bandwidth increases greater than those realized in 33-mode projectors using piezocrystals. This research studies the shear-mode behavior of PMN-PT piezocrystals for use in sensors and projectors. By measuring the response of the materials to high and low level electrical bias and excitation fields, frequency, and temperature, the materials’ effective material properties as a function of these operational variables were determined. [Work sponsored by ONR and NUWC ILIR.]
Frequency shift of a rotating-imbalance vibration source caused by radiative damping in the surrounding medium
Authors: Novascone Stephen R. , Anderson Michael J. , Weinberg David M. , Cole Jack H.
Published: October 2013

The motion of vibrating bodies in a surrounding fluid is often used to infer the transport properties of the fluid. A new sensor configuration is presented that consists of a rotating imbalance source radiating into an unbounded fluid medium. Under these circumstances, the reaction of the fluid medium onto the vibration source includes a steady state torque that opposes the applied torque required to sustain the rotating imbalance. This reaction torque causes a shift in frequency of the vibration source. The frequency shift is related to the density of the surrounding fluid medium and vibration source characteristics. A description of measurements taken with a rotating-imbalance source located in unbounded water and air is provided. The total mass, eccentricity, and length of the source were 4.1 kg, 3.28(10−4) kgm, and 0.432 m, respectively. Motive torque to drive the imbalance was provided by a permanent-magnet dc motor. For an applied dc voltage that caused the source to operate at a nominal frequency near 150 Hz, a frequency shift of approximately 11 Hz was observed when the source was moved from air to water. Experimentally measured frequency shifts compared favorably with predictions provided by a nonlinear steady state model of the source and surrounding medium.
A new inversion method (SUB-RIGS) based on range-sensitive frequency-subspacing and reduced iterated grid searches
Authors: Tolstoy A.
Published: October 2013

Propagation for a range-independent, multi-layered test case (Na or Workshop ‘97) indicates that the highly variable bottom sound-speed profile can be well represented by only a few, e.g., three, linear layers (one layer at the highest frequency, three at the lowest). Thus, at the low frequencies of interest here (less than 500 Hz) transmission loss as a function of range can usually be well predicted using only a few simple sediment layers. This suggested a new inversion method based on range-sensitive frequency-subspacing plus reduced iterated grid spacing (SUB-RIGS). The method is now fully developed and uses the RAMGEO PE propagation model. This paper will discuss the method, pitfalls of the method, and newly successful inversion results for selected test cases (TC1 and CAL from the recent Stennis workshop of May 2001).
Synchronization of HIFU therapy system with an arbitrary ultrasound imager
Authors: Owen Neil , Bailey Michael , Hossack James , Crum Lawrence
Published: October 2013

Synchronization for image guided therapy using high intensity focused ultrasound (HIFU) and imaging ultrasound is achieved with a new technique that uses the focused transducer as a receiver that can detect the acoustic pulses created by the imaging probe. Without synchronization, interference from the high intensity source occludes the imager’s display unpredictably, degrading the quality of the system. An imaging probe (Sonosite 180) is registered with a HIFU transducer (d=33 mm, roc=55 mm, f=3.5 MHz) such that the scan line bisects the single element focus. When acoustically coupled through a scattering medium, imaging pulses are passively detected with the HIFU transducer and electronically conditioned into a TTL level trigger. A LabVIEW program uses the trigger to create a pulse width modulated signal that controls the timing of HIFU excitation during treatment. Detection takes less than 1% of the time between displayed images when the imager is running at 20 frames per second. HIFU excitations are programmed to occur such that the single element focus is free of interference when viewed with the imager during treatment. With no electrical connections for this new, simple technique, an arbitrary imager can be selected for synchronized image guided therapy. [Work supported by NSBRI.]
Optimized hyperthermia treatment of prostate cancer using a novel intravavitary ultrasound array
Authors: Al-Bataineh Osama M. , Smith Nadine B. , Keolian Robert M. , Sparrow Victor W. , Harpster Lewis E.
Published: October 2013

Localized uniformly distributed ultrasound-induced hyperthermia is a useful adjuvant to radiotherapy in the treatment of prostate cancer. A two-dimensional, 20×4 element, transrectal phased-array probe was designed to deliver a uniform and controllable amount of heat directly to the prostate without damaging the rectal wall or surrounding tissue. A three-dimensional prostate model was created using anatomical markers from the Visible Human Project to optimize the array. Sound speed, density, and absorption parameters were mapped to hue, saturation and value of the photographic data to simulate sound propagation through inhomogeneous tissue using the k-space method. To satisfy the requirements of this method from 1.2 to 1.8 MHz, the grid was adjusted to have 5 points per millimeter in each Cartesian direction. A spherical wave pulse was propagated through the model using tapered absorption boundary conditions. The expected temperature rise due to sound was obtained using the bioheat transfer equation. Optimal insonification parameters that uniformly heat the prostate to 43°C for 40–60 minutes were determined for use in the construction of a clinical hyperthermia array. [Research supported by the Department of Defense Congressionally Directed Medical Prostate Cancer Research Program.]
Vibrational modes of the reed in a reed organ pipe
Authors: Huber T. M. , Collins B. A. , Pineda M. , Hendrickson C.
Published: October 2013

We will describe a series of measurements of the vibrational modes of the reed in a reed organ pipe. These measurements were performed using a Polytec PSV-300 scanning vibrometer, which allows the vibrational deflection shape to be determined at any frequency. In addition to blowing the reed pipe in a standard fashion, a mechanical driver was used to excite the reed. Using both excitation sources, a number of deflection shapes were observed including simple cantilever, torsional, and higher-order shapes corresponding to higher-order cantilever and torsional modes. As expected, the observed frequencies of the mechanically driven modes were not integer multiples of the fundamental, and were consistent with theoretical predictions. The reed pipe was also excited in a standard manner using an organ blower. This raised integer multiples of the fundamental frequency as high as 20 kHz within two decades of the velocity amplitude of the fundamental. Torsional and other deflection shapes were present, however nonlinear interactions in the system caused them to be shifted from their mechanically driven frequencies. In some cases, significant vibration was observed in the tuning wire and the section of reed above the tuning wire that was previously considered to be clamped.
Field normalization techniques and practices for determining sound isolation and impact insulation
Authors: LoVerde John J. , Dong David W.
Published: October 2013

The International Building Code (IBC) includes minimum acceptable acoustical performance for floor/ceiling assemblies separating dwelling units. Field tests for determining the Normalized Noise Isolation Class (NNIC) and Field Impact Insulation Class (FIIC) of an assembly require the measurement of the decay rate of the receiving room and the normalization of the sound pressure levels, as set forth in ASTM standards E336 and E1007. The normalization is intended to improve comparability of test results by removing the effects of receiving room absorption. Surprisingly, the normalization procedure is substantially different between these two types of tests. The FIIC normalization is based on the laboratory Impact Insulation Class (IIC) test using a standard room absorption of 10 metric sabins. The NNIC normalization is based on a 0.5-s reverberation time, which is assumed normal in a furnished habitable dwelling space. This difference in normalization procedure for the same receiving room potentially yields different results of NNIC and FIIC as compared with their respective non-normalized values. This will be illustrated with examples of actual field tests. The effectiveness and suitability of the normalization procedures in the field setting are compared and evaluated including the use of the California Building Code modification to FIIC.
Parametric wave phase conjugation of nonlinear ultrasound waves
Authors: Brysev Andrew , Mikhalevich Vladislav , Streltsov Vladimir
Published: October 2013

Real time acoustic wave phase conjugation (WPC), based on parametric self-consistent physical mechanisms, was realized up to the present time only for the monochromatic waves [A. P. Brysev et al., Phys.-Usp. 41, 793 (1998)]. Here the possibility of WPC of nonmonochromatic ultrasound waves is considered. For simultaneous WPC of the entire series of spectral components generated by nonlinear propagation of the incident wave we propose the use of phonon-plasmon interaction in piezosemiconductors. WPC of nonlinear acoustic waves can be accomplished by modulation of the electron density provided by a sequence of short laser pulses pumping the sample. If the periodicity of the optical pulses is half the period of the fundamental component of the acoustic wave, such wide-band, excitation leads to self-synchronized parametric conjugation of each spectral component in the incident wave. The conjugation efficiency depends sharply on relations between acoustical frequency content, laser pulse duration, and interband relaxation time. It is shown that under certain conditions the time profile of the conjugate wave may be efficiently controlled by varying the duration of the laser pulses. The time profile of the conjugate wave is investigated for some physical conditions of practical interest.
Evaluation of a model of auditory source width based on the interaural cross-correlation coefficient
Authors: Mason Russell , Brookes Tim , Rumsey Francis
Published: October 2013

A model of human perception of auditory source width has been developed, based on the interaural cross-correlation coefficient (IACC). The following factors differentiate it from more commonly used IACC-based models: the use of a running analysis to quantify variations in width over time; half-wave rectification and low pass filtering of the input signal to mimic the breakdown of phase locking in the ear; compensation for the frequency and loudness dependency of perceived width; combination of a model of perceived location with a model of perceived width; and conversion of the results to an intuitive scale. Objective and subjective methods have been used to evaluate the accuracy and limitations of the resulting model.
Experimental evaluation of bone quality using speed of sound measurement in cadaver mandibles
Authors: Al Haffar Iyad , Padilla Frederic , Laugier Pascal , Nefussi Raphael , Kolta Sami , Foucart Jean-Michel
Published: October 2013

This study is the first attempt to use speed of sound (SOS) as a new ultrasonic diagnostic tool for bone quality assessment before oral implant treatment. The objective is to demonstrate the in vitro feasibility of local SOS measurement at the mandible, and to investigate the relationships between mandibular SOS and local bone mineral density (BMD) and the ratio between the trabecular and cortical thickness (Tb.Th/Cort.Th). Fourteen excised human mandible were measured in transmission with a pair of flat 1.6-MHz central frequency transducers. Three regions of interest (ROIs) were selected in the specimens: incisor, premolar and molar regions. Ten measurements with repositioning were performed on each ROI to determine the short-term precision. Dual x-ray absorptiometry scans were performed on the samples for local BMD measurements. Computed tomography (CT) was used to determine mandibular cross-sectional morphological measurements. SOS measurements at different sites were significantly different, reflecting the heterogeneity between the different sites. A strong linear relationship was found between SOS and BMD (r2=0.68, p<0,0001) while a nonlinear relationship was found between SOS and Tb.Th/Cort.Th (r2=0.48, p<0,0001). This study demonstrates in vitro the feasibility of SOS measurement at the mandible. In vitro mandibular SOS reflects local BMD and Tb.Th/Cort.Th before implant.
Ultrasonic wave propagation in cortical bone mimics
Authors: Dodd Simon P. , Cunningham James L. , Miles Anthony W. , Humphrey Victor F. , Gheduzzi Sabina
Published: October 2013

Understanding the velocity and attenuation of ultrasonic waves in cortical bone is important for studies of osteoporosis and fractures. In particular, propagation in free- and water-loaded acrylic plates, with a thickness range of around 1–6 mm, has been widely used to mimic cortical bone behavior. A theoretical investigation of Lamb mode propagation at 200 kHz in free- and water-loaded acrylic plates revealed a marked difference in the form of their velocity and attenuation dispersion curves as a function of frequency thickness product. In experimental studies, this difference between free and loaded plates is not seen. Over short measurement distances, the results for both free and loaded plates are consistent with previous modeling and experimental studies: for thicker plates (above 3–4 mm), the velocity calculated using the first arrival signal is a lateral wave comparable with the longitudinal velocity. As the plate thickness decreases, the velocity approaches the S0 Lamb mode value. Wave2000 modeling of the experimental setup agrees with experimental data. The data are also used to test a hypothesis that for thin plates the velocity approaches the corresponding S0 Lamb mode velocity at large measurement distances or when different arrival time criteria are used. [Work supported by Action Medical Research.]
Noise-robust speech recognition using multi-band spectral features
Authors: Nishimura Yoshitaka , Shinozaki Takahiro , Iwano Koji , Furui Sadaoki
Published: October 2013

In most of the state-of-the-art automatic speech recognition (ASR) systems, speech is converted into a time function of the MFCC (Mel Frequency Cepstrum Coefficient) vector. However, the problem with using the MFCC is that noise effects spread over all the coefficients even when the noise is limited within a narrow frequency band. If a spectrum feature is directly used, such a problem can be avoided and thus robustness against noise could be expected to increase. Although various researches on using spectral domain features have been conducted, improvement of recognition performances has been reported only in limited noise conditions. This paper proposes a novel multi-band ASR method using a new log-spectral domain feature. In order to increase the robustness, log-spectrum features are normalized by applying the three processes: subtracting the mean log-energy for each frame, emphasizing spectral peaks, and subtracting the log-spectral mean averaged over an utterance. Spectral component likelihood values in each frame are weighted by normalized spectral level (spectral peaks) or SNR of each component. Experimental results using babble noise-added speech show that recognition performance is improved by the proposed method in comparison with the MFCC-based method. The performance is further improved by spectral-peak weighting and SNR-based frequency-band weighting techniques.
On audio-visual synchronization for viseme-based speech synthesis
Authors: Xue Jianxia , Alwan Abeer , Auer Edward T. , Bernstein Lynne E.
Published: October 2013

In viseme-based visual speech synthesis [e.g., T. Ezzat and T. Poggio, Int. J. Comput. Vision 38, 45–57 (2000)], it is frequently assumed that each viseme can be represented by an image which corresponds to the temporal mid-point of the phoneme’s acoustic segment. We investigated the validity of this assumption in a study of 3-D motion data extracted from marker positions on the face of one talker. Using principle components analysis (PCA), the first five principle motion tracks comprising the lips and the jaw were studied. The temporal positions of the local extrema in the principle motion tracks were analyzed. Statistics of the distances between these local extrema and the mid-points of the corresponding acoustic segments were compared. Results showed that the local extrema of the motion tracks were, for the most part, not well-aligned to the phoneme’s acoustic midpoint with a few exceptions. For example, for /s/ the local extrema were well aligned (small variance), while for /m/ and /f/, alignments pattern could be found for several, but not all, tokens. The results suggest that phonetic context and speaking rate must be taken into account when characterizing facial configurations in visual speech synthesis. [Work supported in part by the NSF.]
Emotion to emotion speech conversion in phoneme level
Authors: Bulut Murtaza , Yildirim Serdar , Busso Carlos , Lee Chul Min , Kazemzadeh Ebrahim , Lee Sungbok , Narayanan Shrikanth
Published: October 2013

Having an ability to synthesize emotional speech can make human–machine interaction more natural in spoken dialogue management. This study investigates the effectiveness of prosodic and spectral modification in phoneme level on emotion-to-emotion speech conversion. The prosody modification is performed with the TD-PSOLA algorithm (Moulines and Charpentier, 1990). We also transform the spectral envelopes of source phonemes to match those of target phonemes using LPC-based spectral transformation approach (Kain, 2001). Prosodic speech parameters (F0, duration, and energy) for target phonemes are estimated from the statistics obtained from the analysis of an emotional speech database of happy, angry, sad, and neutral utterances collected from actors. Listening experiments conducted with native American English speakers indicate that the modification of prosody only or spectrum only is not sufficient to elicit targeted emotions. The simultaneous modification of both prosody and spectrum results in higher acceptance rates of target emotions, suggesting that not only modeling speech prosody but also modeling spectral patterns that reflect underlying speech articulations are equally important to synthesize emotional speech with good quality. We are investigating suprasegmental level modifications for further improvement in speech quality and expressiveness.
Analysis and synthesis of laughter
Authors: Sundaram Shiva , Narayanan Shrikanth
Published: October 2013

There is much enthusiasm in the text-to-speech community for synthesis of emotional and natural speech. One idea being proposed is to include emotion dependent paralinguistic cues during synthesis to convey emotions effectively. This requires modeling and synthesis techniques of various cues for different emotions. Motivated by this, a technique to synthesize human laughter is proposed. Laughter is a complex mechanism of expression and has high variability in terms of types and usage in human–human communication. People have their own characteristic way of laughing. Laughter can be seen as a controlled/uncontrolled physiological process of a person resulting from an initial excitation in context. A parametric model based on damped simple harmonic motion to effectively capture these diversities and also maintain the individuals characteristics is developed here. Limited laughter/speech data from actual humans and synthesis ease are the constraints imposed on the accuracy of the model. Analysis techniques are also developed to determine the parameters of the model for a given individual or laughter type. Finally, the effectiveness of the model to capture the individual characteristics and naturalness compared to real human laughter has been analyzed. Through this the factors involved in individual human laughter and their importance can be better understood.
Uncertainties in measurement of spatial parameters in room acoustics
Authors: Vorlaender Michael , Witew Ingo
Published: October 2013

With the goal to assess spatial impression, such as apparent source width and envelopment in concert halls, lateral energy fraction is a fairly simple measure to be determined as a single number parameter. ISO 3382 describes the procedure to conduct the measurements and also defines certain quality requirements imposed on the loudspeakers and the microphones. This case study portrays how changes in the source and the microphone character are reflected in the parameter. This aspect is investigated on the grounds of measurements and simulations. In a measurement scenario, LF is calculated for different sound sources, different source setups and different microphone arrangements. In simulations, the effects of variations of the directional pattern of the microphone on the measurement result are investigated. The results suggest that despite the proven background of the lateral fraction parameter, the measurement results are distorted with noteworthy uncertainties that originate from deficiencies in measurement equipment.
Interaural cross-correlation coefficient, apparent source width, and time/frequency characteristics of binaural running cross-correlation
Authors: Conant David A.
Published: October 2013

The interaural cross-correlation coefficient (IACC) descriptors attempt to characterize in a single number the binaural cross-correlation function at the expense of losing much detail in a manner similar to, but more problematic than, such descriptors as NC, STC, and NRC because much frequency- and rich time-domain information is lost. Recent computer simulations by Mason illuminated these problems and further stimulated the present study. Old binaural impulse recordings run through an analog computer algorithm (drawn from physiological modeling) were re-examined in an attempt to reveal trends and relationships that the current descriptors cannot. Issues of the time and frequency variance of the measured running coefficient are discussed in terms of apparent source width (ASW) for music in Troy Music Hall and simpler spaces.
Measurements and modeling of low-frequency scattering from fish on the New Jersey shelf
Authors: Soukup Raymond J. , Nero Redwood W. , Shepard Timothy M.
Published: October 2013

Low-frequency (400–2000 Hz) scattering strength measurements were obtained from aggregations of fish on the New Jersey shelf using a co-located transducer and vertical line array receiver. Concurrent measurements with a fisheries echosounder revealed the presence of nighttime layer(s) and daytime schools. The day–night behavior is consistent with several species of fish found on the New Jersey shelf, as are the observed resonance frequencies near 800 Hz. Data-model comparisons are used to characterize both the strength and bandwidth of the frequency response, as well as its dependence on fish type and behavior. From these data, parameters such as fish depth, density and size can be estimated, and, in turn, the scattering strength as a function of frequency and grazing angle can be predicted and then compared with those of other potential scattering mechanisms. The implications of the fish scattering to reverberation and clutter are discussed. [Work supported by ONR.]
Coupling finite element and iterative methods on a solid–solid boundary—Computation of the radiation of buried directional piezoelectric transducers for seismic applications
Authors: Berraki Madjid , Dubus Bertrand , Baroni Axelle
Published: October 2013

Based on a theoretical directional source concept for four dimensional seismic monitoring (described in another communication), this work is dedicated to the design of the directional piezoelectric transducer. To describe the interaction of a piezoelectric source with its environment, a model coupling the finite element method with the impedance matrix of the soil is developed. The piezoelectric source and a surrounding spherical soil volume are described using finite element; on the surface of the spherical volume, a condition taking into account the external medium is applied by using an iterative method [Thiruvenkatachar et al., Proc. R. Soc. London, Ser A 309, 331–344 (1969)]. This numerical process is then implemented in the finite element code ATILA which is devoted to the modeling of piezoelectric structures. A transducer acting as the directional concept is designed and its far field radiation patterns are computed. [Work supported by an I.F.P. grant.]
Progress in speech research for telecommunications in the last five decades
Authors: Juang Biing Hwang
Published: October 2013

Speech is the most natural form of human communications. A significant portion of speech research in the last century was devoted to the development of knowledge and technologies that aim at extending such a fundamental human capability over a long distance and at automating the support for such an extension. For the former, devices such as new acoustic transducers and techniques such as speech coding and echo cancellation have led to superb speech communication quality even for people located continents apart. For the latter, techniques in speech synthesis, recognition and understanding have been incorporated in various communication systems that automate billions of telephone calls or remote transactions of various sorts with remarkable success. Jim Flanagan, who had led the team on speech and acoustics in Bell Labs for over three decades, was very much in the center of this tremendous progress. In this talk, we highlight some of the milestones, many directly inspired by Jim Flanagan, that were achieved in the last few decades in the area of speech technologies and systems that have brought us benefits in our everyday life.
Fifty years of progress in speech understanding systems
Authors: Zue Victor
Published: October 2013

Researchers working on human-machine interfaces realized nearly 50 years ago that automatic speech recognition (ASR) alone is not sufficient; one needs to impart linguistic knowledge to the system such that the signal could ultimately be understood. A speech understanding system combines speech recognition (i.e., the speech to symbols conversion) with natural language processing (i.e., the symbol to meaning transformation) to achieve understanding. Speech understanding research dates back to the DARPA Speech Understanding Project in the early 1970s. However, large-scale efforts only began in earnest in the late 1980s, with government research programs in the U.S. and Europe providing the impetus. This has resulted in many innovations including novel approaches to natural language understanding (NLU) for speech input, and integration techniques for ASR and NLU. In the past decade, speech understanding systems have become major building blocks of conversational interfaces that enable users to access and manage information using spoken dialogue, incorporating language generation, discourse modeling, dialogue management, and speech synthesis. Today, we are at the threshold of developing multimodal interfaces, augmenting sound with sight and touch. This talk will highlight past work and speculate on the future. [Work supported by an industrial consortium of the MIT Oxygen Project.]
The ancients have stolen our inventions—Recently discovered documents of Vern O. Knudsen
Authors: Shaw Neil A. , Brown Charlotte B.
Published: October 2013

Vern O. Knudsen was a founder of the Acoustical Society of America (1928), a member of the Bell Telephone Laboratories staff (1918), a respected professor of physics at UCLA (1922–1958), a Chancellor of UCLA (1959–1960), and a consultant in acoustics. Recently, a trove of Dr. Knudsen’s papers and books was gathered by his family and donated to the UCLA Dept. of Special Collections where they will be added to the existing 44 boxes of the Vern Oliver Knudsen Papers (UCLA Manuscript Collection No. 1153). These newly acquired documents and architectural drawings illustrate Dr. Knudsen’s pioneering work in classroom acoustics, room acoustic design, and sound propagation–aspects of acoustics that are still investigated today, 80 years later. The presentation will include a review of selected items from the Knudsen Papers including: his work for clients such as the Hollywood Bowl (1926–1929) and MGM Studios; his work with architects in the design of classrooms, performance and production spaces; Dr. Knudsen’s basic physical research; and his correspondence with luminaries from numerous fields. Many in the audience will rediscover that they do, indeed, follow in the footsteps of a giant.
Rock art acoustics
Authors: Ronsse Lauren M.
Published: October 2013

The relationship between the location of rock art and the acoustical properties of its immediate environment has been a source of previous investigation. The markings the early peoples created on rock formations open a fascinating portal into the exploration of their lifestyles. Previous research has shown that often ancient rock art was placed on surfaces or in locations that echoed, whereas locations without such echoes were undecorated [S. J. Waller, 2002 Rock Art Acoustics in the Past, Present, and Future. 1999 International Rock Art Congress Proceedings 2, 11–20]. Could the acoustical characteristics of the decorated outcroppings have been perceived by the early peoples of the American Plains? A detailed study of six rock art sites located in Ellsworth County, KS has been conducted to determine the acoustical properties of these sites. At each site, various impulsive sounds were created to energize the space. The impulse responses were recorded and analyzed using two acoustic recording and analysis computer programs. This study did find echoes occurring at the decorated sites. These echoes were quantifiably louder than any reflection of sound measured at the surrounding undecorated locations.
The penguin and puffin coast: Application of a micro-perforated membrane stretch ceiling
Authors: Pride Jeff B. , Weissenburger Jason T.
Published: October 2013

The St. Louis Zoo has been undergoing major renovations that make it one of the premier zoos in the world. The Penguin and Puffin Coast, a walk through exhibit, is as near to a perfect habitat reproduction as is technologically feasible. Reproduced are a rugged coastline with craggy rock outcroppings, frigid water and a barrel vault ceiling that has theatrical lighting that can be used to simulate a colorful sunrise, a sunset over the horizon or the reversed seasons. Sounds of crashing waves and a sea lion’s bark can be heard in the distance. A micro-perforated membrane stretch ceiling was chosen for its ability to easily conform to the undulations required for the sky, its durability in the moist confines of the exhibit and, last but not least, its ability to provide much needed acoustical absorption, all with the same product. This talk will discuss experiences with the micro-perforated material, review the acoustical efficacy of the installation and show photographs of the construction from essential beginning to final product. A photo or two of the penguins and puffins will also be shown.
Influence of surface scattering characteristics on the sound quality of reverberation
Authors: Mueller Jacob , Kleiner Mendel , Xiang Ning , Torres Rendell
Published: October 2013

The influence of the scattered sound from different sound diffusing surfaces on the subjective characteristics of the late reverberation of a room was studied using a simulation approach. The impulse response of various scale model scatterers was measured for a set of angles and used in combination with a simple room model for auralization. As shown by Kleiner one can quite easily hear the differences between the scattered sound from different scatterers [M. Kleiner et al., Proc. 93rd Audio Eng. Soc. Convention, San Fransisco. Vol. 43, ‘‘Auralization of QRD and Other Diffusing Surfaces using Scale Modelling’’ (1992)]. The results obtained here, for the late reverberation, are not as clear, indicating that the ‘‘individual’’ sound of scattering surfaces will influence primarily the sound quality of the early part of the reverberation. [Work supported by RPI.]
Audiology to ecology: Auditory scene analysis goes underwater
Authors: Gisiner Robert
Published: October 2013

For decades the study of marine mammal audiology was considered an arcane branch of comparative psychophysics with little to offer the marine mammal ecologist. But in the past decade the oval window of the marine mammal ear has effectively become the ecologist’s window into a marine ecosystem that truly is a world of sound. We are learning to listen to the ocean as marine mammals do, in order to better understand an environment long hidden from our view. And we are learning about the importance of sound to marine mammals, including the effects of our own noisy entry into their world. The past decade of revolutionary change in the use of sound to study marine mammals, and the associated revolution in our appreciation of marine mammal uses of sound, will be reviewed. We now see the ocean world through a marine mammal’s ears, thanks to Ron Schusterman and a few dedicated colleagues who have opened our eyes, and ears, to the importance of audiology in ecology.
Hey Ron manatees do not echolocate either; the underwater hearing and acoustical behavior of West Indian manatees
Authors: Gerstein Edmund , Gerstein Laura , Forsythe Steve , Blue Joseph
Published: October 2013

A comprehensive series of underwater psychoacoustic tests were conducted with captive manatees to measure their hearing abilities under varying acoustic conditions. Forced-choice paradigms with either a staircase, or method of constants, psychometric were used to define their audiogram, critical ratios, temporal integration, and directional hearing abilities. Pure tones, complex, broad and narrow-band noise were presented with a masker, at different intensities, to measure simultaneous masking effects at ambient levels recorded in manatee habitats. Masked thresholds across frequencies increased linearly with masker intensity. Critical ratios for pulsed signals were lower than nonpulsed, suggesting an inhibitory process affecting perception of nonpulsed tones. Comparisons with other mammals indicate manatees have acute filtering abilities for detecting pulsed sounds. While manatees do not exhibit a vocal repertoire to account for acute filtering, they are passive listeners, well adapted to selectively filter out continuous noise in favor of biologically significant sounds like their own 200-ms calls. Playbacks of band-limited calls suggest loudness summation across multiple critical bands may enable manatees to detect and locate their calls near or below ambient levels. This may explain why calibrated calls recorded in the wild exhibit no Lombard shifts. Low source levels and pulse rates negate their utility for active echolocation.
Underwater hearing thresholds in pinnipeds measured over a 6-year period
Authors: Southall Brandon L. , Schusterman Ronald J. , Kastak David , Reichmuth Kastak Colleen
Published: October 2013

While absolute hearing thresholds have been obtained for some marine mammals, few published data are available on how measurements of individual auditory sensitivity may change over relatively long periods of time. Studies that have investigated temporal changes in sensitivity have typically focused on animals in which differences in hearing are anticipated (age-related hearing loss). This study investigated the replicability of underwater hearing thresholds in prime-aged individuals of three pinniped species over a 6-year period. Aside from their age and experience with behavioral signal detection tasks, test subjects were of similar physical condition throughout this experiment. They were tested in the same enclosure at similar test frequencies (0.1–6.4 kHz) using identical methodology and criteria. Underwater hearing thresholds obtained throughout this testing period were not significantly different. These data indicate that underwater hearing sensitivity may remain relatively stable over long periods in nonsenescent marine mammals, including those regularly exposed to noise. Further, our results suggest that variability in testing equipment and experimental personnel may have little impact on behavioral hearing data, as long as similar testing methodologies and subject response bias are carefully maintained.
Testing the acoustic prey debilitation hypothesis: No stunning results
Authors: Benoit-Bird Kelly , Au Whitlow , Kastelein Ronald , van de Huel Sander
Published: October 2013

We examined the hypothesis that sounds produced by odontocetes can debilitate fish by testing the effects of three odontocete-like pulsed signals on three individuals of each of three fish species: sea bass, cod, and herring. We used a high-frequency click with a center frequency of 120 kHz exposing the fish to approximately 112 dB, a mid-frequency click with a center frequency of 70 kHz and 208 dB exposure level, and a low-frequency click with a center frequency of 40 kHz and 193 dB exposure level. Individual fish were placed in a 0.3-m-diam net enclosure immediately in front of a transducer. Each fish was allowed to remain in the experimental set up for at least 3 min prior to exposure to the clicks which were presented at a rate of 100 pulses/s grading to 700 pulses/s in 1.1, 2.2, and 3.3 s. Sea bass were also exposed to a constant pulse rate of 700 pulses/s for exposures of up to 30 s. No effect was observed in any of the fish for any signal type or pulse modulation rate. Based on our results, the hypothesis that acoustic signals of odontocetes alone can disorient or stun prey cannot be supported.
Acoustic effects in presence of internal solitons in shallow water
Authors: Katsnelson Boris
Published: October 2013

The given lecture (mini-tutorial) is dedicated to description of recent efforts (last 10–15 years) in experimental observation and theoretical modeling of the sound propagation in shallow water in the presence of traveling internal solitonlike waves (ISW). It contains a review of the main experimental observation of acoustical effects (Rubinstein and Rubinstein and Brill, Zhou et al., Badiey et al., etc.) The main theoretical approaches can be divided in dependence on orientation of ISW wave front: (1) Modes coupling due to ISW, traveling along acoustic track. Resonance effects in sound propagation, resonance coupling by packets and separate solitons (J-X Zhou, Preisig and Duda, etc.) are considered. (2) Horizontal refraction (HR) caused by ISW crossing acoustic track. Technique of vertical modes and horizontal rays, vertical modes and PE in horizontal plane and modeling of acoustic effects in typical conditions of Barents sea are shown. Analysis of specific peculiarities due to HR (synchronicity, periodicity, and depth dependence of intensity fluctuations) is given. Experimental observations of acoustic effects in the SWARM’95 (broadband sound propagation, shot and LFM signals) are presented. New specific features of signals, passing through ISW space-frequency horizontal structure, and fluctuations of modal spectrum are demonstrated, and experimental setup to register these is discussed. [Work was supported by RFBR and CRDF.]
Estimating internal wave statistics from underwater acoustic transmission scintillation measurements on the New Jersey shelf with a 3-D stochastic model
Authors: Ratilal Purnima , Chen Tianrun , Makris Nicholas
Published: October 2013

The acoustic intensity expected after transmission through random inhomogeneities in an ocean waveguide is analytically expressed in terms of modal dispersion, attenuation, and energy redistribution in a 3-D multiple forward scattering formulation [Ratilal and Makris, J. Acoust. Soc. Am. 114, 2428 (2003)]. This approach is used to model forward scattering through a random internal wavefield. Scattering from the density and compressibility inhomogeneities caused by the internal waves is approximated with the Rayleigh–Born series. The model is used to estimate the rms internal-wave height from low-to-mid-frequency underwater acoustic transmission scintillations measured during the Main Acoustic Clutter experiment of 2003 in the New Jersey Strataform area. Estimated internal wave height standard deviations matched those obtained from independent temperature and CTD measurements and suggest that the internal wave field was not temporally stationary.