bluuebunny/crossref_metadata_2025 huggingface dataset:
High-resolution imaging of fault zone structures
Authors: Peng Zhigang , Ben-Zion Yehuda
Published: October 2013

Damaged fault zone (FZ) rocks with high crack density are expected to produce several indicative wave propagation signals. These include scattering, anisotropy, nonlinearity, and FZ guided head and trapped waves. These signals can be used to obtain high-resolution imaging of the FZ structures and to track possible temporal evolution of FZ properties. Results associated with systematic analysis of such signals recorded at several large strike-slip FZs can be summarized as follows: The observed FZ trapped waves are generated by relatively shallow structures that extend only over the top ∼3−−4km of the crust. The shallow trapping structure in the North Anatolian fault (NAF) is surrounded by broader anisotropic and scattering zones that are also confined primarily to the top 3 km. Systematic analyses of anisotropy and scattering around the NAF do not show precursory temporal evolution of properties. However, the scattering results show clear co-seismic changes and post-seismic logarithmic recovery. These effects are likely to reflect mostly changes in properties of the shallow crust in response to strong shakings of nearby major earthquakes. Analyses of FZ head waves along the San Andreas Fault point to the existence of material interfaces that extend to the bottom of the seismogenic zone.
Vis-a-vis: Reading texts in real-time
Authors: Rovan Joseph
Published: October 2013

This presentation addresses the formal and psychological aspects of Vis-a-vis as a way of framing the attitude of the technology itself. Based on a text by Rilke, the work situates a solo singer within a dense sonic landscape whose electronic sounds are based entirely on her voice. The interactive score, written in MaxMSP, makes the computer a virtual performer, listening and responding to the changing musical events in its own terms. In this new 5.1 mix a variety of real-time processes are used on the voice, shifting from scene to scene, according to the tone of the text. Among the real-time processes used are spectral analysis/resynthesis, granular sampling, harmonization, frequency shifting, and envelope tracking, among others. In Vis-a-vis the computer functions like a virtual performer, listening to the changing musical events phrasing, dynamics, and register of the singer, and responds accordingly, in its own terms. The point is to capture something of the improvisatory spirit that is part of any live performance, and to create an environment in which the singer and computer can interact as a duo, responding to each other’s musical decisions in an immersive sonic environment.
Improvising with spaces
Authors: Oliveros Pauline
Published: October 2013

This paper explores qualitative changes that occur in voices and instruments in relationships with changing spaces that ordinarily are held in a stationary paradigm of performance practice, spatial transformations, and the effect on sounds in multi-channel speaker systems. Digital technology allows one to compose and improvise with acoustical characteristics and change the apparent space during a musical performance. Sounds can move in space, and space can morph and change, affecting the sounds. Space is an integral part of sound. One cannot exist without the other. Varieties of sounds and spaces combine in symbiotic relationships that range from very limited to very powerful for the interweaving expressions of the music, architectures, and audiences.
Spatial treatment of sound sources in John Mallia’s ‘‘Anastasis.’’
Authors: Mallia John
Published: October 2013

This presentation will outline the spatial techniques and treatment of sounds in my five-channel acousmatic composition entitled ‘‘Anastasis.’’ The orchestration of sound objects in the field of five loudspeakers adheres to an elastic gravitational plan assigned to each point in space. Generally speaking, the field of five speakers is weighted so that rear point sources support sounds lower in pitch than those occurring in the front of the projection plane where frequencies are raised. The relationship between each point source and its corresponding interval of transposition is in constant flux and its size serves to emphasize the degree of spatial depth present at any given moment. No attempt is made to precisely emulate the way in which we hear sounds move in the real world, but, rather, sound sources are intuitively, and experimentally, decorrelated to support and exaggerate the listeners experience of space. The presentation of this working method will raise questions regarding the compositional effectiveness of experimental spatialization techniques informed by general observations of the physical properties of sound versus methods that attempt to model, more closely and accurately, the predictable behavior of sound in space.
A computational model of bottlenose dolphin sonar: Feature-extracting method
Authors: Zorikov Tengiz V.
Published: October 2013

A process of echo-image formation in bottlenose dolphin perception was investigated in our experiments, in which animals were trained to differentiate passive actual echoes recorded beforehand purposely, as well as echo-like simulated impulses. The results suggest that dolphin, processing echoes within critical interval of time (∼0.2 ms), utilizes the string of three independent, hierarchically organized features (echoes subjective characteristics) being defined by different scales of spectral density oscillation, and energy. Herewith, dolphin is capable to assess features average value over a series of echoes. Distinguishing stimuli, dolphin estimates successively features values from senior to minor, terminating the process at the feature, which contains detectable differences in compared stimuli (the distinctive feature). A procedure of subsequent identification of the reference stimulus can be described by the following decision rule: If the dolphin utilizes some feature as the distinctive one, then in order to preserve the image of the reference stimulus in the animal’s perception, it is necessary and sufficient to preserve the same values of the distinctive feature and all higher ones in order of hierarchy. These data were formalized mathematically and used in our computational model, comparative testing of which has revealed critical capabilities comparable with those of bottlenose dolphins.
Acoustic species identification: When biology collides with physics
Authors: Horne John K.
Published: October 2013

Acoustic species identification remains a long-term goal of fishers, researchers, and resource managers that use sound to locate, map, and count aquatic organisms. Interpreting acoustic data from aquatic organisms requires an understanding of how pressure waves interact with biological targets to produce single or multiple echoes. Intensity and variability of backscattered energy is influenced by physical factors associated with energy propagation through a dense medium, and biological factors including the morphology, ontogeny, physiology, and behavior of targets. Efforts to quantify relative magnitudes and importance of biological factors have resulted in an approach that integrates field and laboratory measurements, numeric backscatter models, and computer visualizations. Acoustic visualizations are used to incorporate representations of the acoustic beam; the shape and composition of targets; target orientation (tilt, yaw, roll) and behavior (individuals and aggregations); and the resulting frequency-dependent backscatter. Exclusive use of acoustics to identify aquatic organisms requires metrics that discriminate among species with similar body types and implementing these metrics in routine data processing. Increased frequency bandwidth and angle-dependent backscatter measurements increase the information content of acoustic data to help achieve this goal. [Work supported by ONR and NOAA Fisheries.]
A three-dimensional, time-dependent simulation of a Turkish cymbal using the finite element method
Authors: Muenster Malte
Published: October 2013

We built computer-aided simulations of several musical instruments to study microstructural behavior of initial transients and eigenvalues. Our finite element model (FEM) of a cymbal is an example for the possibilities of this method. Proceeding from a three-dimensional mindlin plate model, we discovered some former unknown, sometimes moving fundamentals, depending on striking positions, hammering during production process, sizes, forms, and alloys. Special movements of the bell of the cymbal have been investigated. Moreover, experimental studies and simulation are able to be compared directly concerning their variety of dynamic behavior. This leads to more and more precise formulation of requirements of musical instruments. Cymbals are among the oldest instruments. The production techniques, some were real secrets, were given from father to son to the next generations of instrument builders. But only recent developments in musical acoustic research include computational modeling and signal processing power to show that most parts of musical sounds of a cymbal are caused by the features mentioned above, in regard to styles, expression, and instrument qualities important to musicians. Our studies try to give an idea of formulating and influencing sound parameters of musical instruments using FEM simulations. The target is to describe how to build a cymbal fulfilling any condition of sound.
Conservative numerical methods for sound synthesis
Authors: Bilbao Stefan
Published: October 2013

Direct numerical simulation techniques, such as finite difference and finite element methods, are playing an increasingly important role in sound synthesis based on physical models of musical instruments. While they can lead to enormous improvements in sound quality over existing methods, a problem of mounting importance is that of maintaining numerical stability when the system to be simulated is strongly nonlinear, as is the case for many musical instruments. This problem is especially acute if real-time synthesis is to be an eventual goal. Standard stability checking machinery, such as frequency domain (von Neumann) analysis, does not immediately apply, and, often, the most straightforward numerical methods may exhibit such instabilities in an unpredictable manner. In this paper, various techniques for the construction and analysis of numerical methods for strongly nonlinear musical systems are presented; they are based on the translation of the principle of conservation or dissipation of energy to discrete time and can lead directly to sufficient nonlinear stability conditions, without invoking frequency domain concepts. Special attention is paid to the nonlinear string, bar, and plate models. Numerical results and sound examples will be presented.
New developments in speech privacy design
Authors: Roy Kenneth P.
Published: October 2013

The design of architectural spaces for the purpose of speech privacy attainment has been quietly practiced over many years. In the late 1960s and 70s, with the introduction of open-plan office layouts, the need for speech privacy became an issue of productivity, as well as one of confidentiality. Today, with the introduction of government regulations such as HIPAA, the need for confidential speech privacy in the healthcare industry has hit the mainstream of our consciousness, even as individuals. And, in this day of (in)security the issues of espionage and terrorism have implications for architectural acoustic design of spaces for speech security. This paper considers both the architectural design trends and issues, and the measurement and evaluation methods being developed in response to these needs for speech privacy, as we move boldly forward into the next 50 years.
Capture of in vivo biological images below the surface of aqueous media with ultrasound atomic force microscopy
Authors: Maghsoudy-Louyeh Sahar , Du Jikai , Tittmann Bernhard R.
Published: October 2013

Atomic force microscopy (AFM) is a useful tool for measuring sample topography and has been widely applied to imaging of biological cells. The Park Scientific M5 AFM in our laboratory, in addition to measuring sample topography, can also give images of spatial distributions of sample elastic properties through applying an ultrasonic AFM (U-AFM) technique. But the M5 AFM is normally a dry operation AFM, and this makes it unsuitable for imaging in vivo biological cells in aqueous media. To modify the M5 AFM for imaging in aqueous media, both mathematical modeling and physical experimentation were established. A modified AFM system was built based on the theory. As a result, both topography and elastic property images are obtained on biological samples in aqueous media. The details of the modification will be described and examples of under-liquid imaging will be presented.
Different developmental patterns for average performance and performance consistency on basic auditory tasks during adolescence
Authors: Huyck Julia Jones , Wright Beverly A.
Published: October 2013

Learning patterns on auditory discrimination tasks have been observed to differ markedly between average performance (average threshold) and performance consistency (within-subject standard deviation), suggesting that these two measures of performance may be governed by different processes [Wright et al., ARO Abstr. 27, 274 (2004)]. Further supporting this idea, different developmental patterns for average performance and performance consistency are reported here. Naive 8- to 10-year-olds (n=6), 11- to 14-year-olds (n=16), and adults (≥18 years old; n=17) were tested on four auditory detection conditions in which a 10-ms 1-kHz tone was presented (1) immediately before a 300-ms broadband noise, (2) at noise onset, (3) 200 ms after noise onset, or (4) immediately after noise offset. On two of the four conditions (conditions 1 and 4), both average performance and performance consistency improved with increasing age. However, on the remaining two conditions, either average performance improved significantly with increasing age while performance consistency did not (condition 2) or vice versa (condition 3). These results suggest that, in development, the processes underlying average performance may differ from those underlying performance consistency, and, more generally, that different processes may underlie these two measures of performance in many aspects of behavior. [Work supported by NIH/NIDCD.]
Forward masking of spectral modulation
Authors: Borchert Elizabeth M. O. , Wojtczak Magdalena , Viemeister Neal F.
Published: October 2013

Some physiological and psychophysical evidence indicates that spectral shape is processed by means of a Fourier-like analysis of the spectral envelope. A forward masking paradigm in the spectral envelope domain was used to further investigate the properties of such spectral analysis. Detectability of a 50-ms sinusoidal modulation (ripple) in the amplitude spectrum of a broadband noise was measured when it was preceded by either uniform-spectrum noise, or by a noise with a same-frequency ripple (the forward masker). Data showed considerable forward masking of ripple detection when the phase of the masker and that of the signal were the same, but little or no masking when the masker and signal ripples were out of phase. Such results could be explained either by perceptual confusion between the signal and masker or by the adaptation of phase-sensitive, tuned ripple channels. In a follow-up study, the masker consisted of a broadband noise with both an on-frequency and an off-frequency (nonmasking) ripple. Little or no masking was observed in this study, which is consistent with an explanation based on the perceptual similarity between signal and masker. [Work supported by NIH Grant DC00683.]
Spectral correlation of timbral adjectives used by musicians
Authors: Disley Alastair C. , Howard David M. , Hunt Andrew D.
Published: October 2013

As part of a project to develop a synthesis interface which nontechnical musicians should find intuitive, the adjectives musicians use to describe timbre have been studied in a large-scale listening test. Timbral adjectives were gathered from both musicians and previous studies and refined in a pilot experiment to a set of 15 (bright, clear, dull, evolving, gentle, harsh, metallic, nasal, percussive, pure, rich, ringing, thin, warm, and wooden). Fifty-nine English-speaking musicians used these words as rating scales (e.g., bright to not bright) in a listening experiment involving 12 single-note samples chosen to explore the timbre space of Western musical instruments. Twenty-three of those listeners were in a control group who took the test ten times, showing good consistency in their answers. The results demonstrate a good common understanding of adjectives between listeners, and multivariate data analysis techniques were used to exclude poorly understood or highly correlated adjectives. The relationship between the consistently understood adjectives and the spectral features they describe is explored by looking for correlation with a large number of time and frequency domain analyses of the 12 instrument samples. Significant correlation is found between some timbral adjectives and spectral features.
Effect of context on identification of environmental sounds
Authors: Gygi Brian , Shafiro Valeriy
Published: October 2013

This study investigated the role of auditory context in identifying individual environmental sounds. Limited previous research has not demonstrated a facilitatory influence of context on sound identification comparable to the benefits grammatical context provides for identifying speech sounds. Unlike some previous studies, in which context was determined by sound presented sequentially before and after the target environmental sound, in the present experiments the sounds to be identified were mixed in with a background of naturally occurring auditory scenes, such as the ambience of a beach or a street. Thirty-one familiar environmental sounds from previous environmental sounds studies were presented mixed either with congruent scenes (such as hammering at a construction site) or incongruent scenes (such as a horse galloping in a restaurant). The sounds were presented at signal-to-background ratios of −12 and −16 dB and trained listeners identified them using three-letter codes. Results indicate auditory context had a small but significant effect on identification performance. However, contrary to expectations, the sounds were identified more accurately in incongruent scenes (55% correct) rather than congruent ones (46% correct). The differential effects of auditory attention in determining foreground and background sounds will be discussed in connection with the results.
Guided waves for stress corrosion crack detection in pipelines—feature selection and classification
Authors: Albright Austin P. , Varma Venugopal K. , Tucker Raymond W. , Bingham Philip R.
Published: October 2013

This paper describes a wavelet-based analysis of electromagnetic acoustic transducer (EMAT) signals for in-line inspection of flaws in natural gas pipeline. The main objective of the project has been to implement the use of EMATs for pipe flaw detection, specifically the ability to detect stress corrosion cracks (SCCs) that are undetectable by current techniques. In this approach, two EMATs are used; one is the transmitter, while the second one, located a few inches away from the first, is used to receive the induced signal. Using a four-level wavelet decomposition, the EMAT data are filtered based on frequency. The features used to classify are derived from the coefficients representing each level of the four-level decomposition of the signature. The objective of the project was to detect SCC with minimal false positive even if smaller SCCs (shallow) are not identified. Although many features could be used, selecting the right features that results in maximum separation between the classes (SCC flaw, other pipe artifacts, and no flaw) was a challenge. This paper describes the process of down-selecting the feature sets and separating the classes. The results using this approach have shown promise.
Waveguide scattering from flanges, ribs, and defects in fluid-loaded, laminated cylinders
Authors: Stokes Ann , Corrado Charles , McDaniel Gregory
Published: October 2013

The vibration of laminated, fluid-loaded cylinders is efficiently predicted with a wave transmission line analysis. The transmission line approach expresses the motion of homogeneous cylinder sections in terms of propagating and evanescent waves. The full set of wave dispersion relationships is computed with a semi-analytic technique, which uses a finite element radial discretization of the laminated shell and interior fluid. External fluid is represented using a state-space representation of the rational function approximation (RFA). Scattering of waves from discontinuities, including flanges, delamination, and pitting, is predicted through coupling a two-port admittance of the structure or defect to the semi-infinite admittance of the cylinder waveguide. Issues regarding the measurement of scattered and reflected waves, and identification of structural wave numbers, are discussed. The use of causality and reciprocity constraints substantially reduces measurement requirements and noise. By exciting and measuring a mixture of structural waves, defects may be classified and located. An example of predicting and measuring scattering of a defect beyond a flange is presented. [Work sponsored by the Office of Naval Research, Code 33.]
Leaky wave excitation on concave surfaces and hyperbolic Fresnel zones
Authors: Marston Philip L.
Published: October 2013

Leaky waves are waves guided by elastic structures having phase velocities exceeding the speed of sound in the surrounding fluid. When analyzing the excitation of leaky waves on smoothly curved elastic structures it is often helpful to determine the Fermat paths. Those paths satisfy Fermat’s principle for the combined acoustic propagation in the fluid and guided propagation on the structure. It is also helpful to determine the shape of the Fresnel zones associated with deviations from Fermat paths. That information is directly useful for calculating guided leaky wave amplitudes [P. L. Marston, ‘‘Spatial approximation of leaky wave surface amplitudes for three-dimensional high-frequency scattering: Fresnel patches and applications to edge-excited and regular helical waves on cylinders,’’ J. Acoust. Soc. Am. 102, 1628–1638 (1997)]. The Fresnel zones associated with the external excitation of helical leaky waves on submerged circular pipes or cylinders were previously shown to be elliptical. The resulting leaky wave amplitudes are in agreement with amplitudes derivable by other methods and with experiments. In the present work, the analysis is generalized to excitation of leaky waves by ultrasound incident from the concave side of cylindrical shells or pipes. Even though the resulting Fresnel zones are approximately hyperbolic in shape, ray approximations for the amplitude are applicable when expressed using the Hessian of the phase deviation. [Supported by the Office of Naval Research.]
Ultrasonic nondestructive evaluation in thin-walled concrete for flaw detection
Authors: Pedrick Michael K. , Tittmann Bernhard R. , Iyer Shivprakash
Published: October 2013

Accurate inspection techniques for today’s infrastructure have become an area of great interest. Several ultrasonic techniques for testing and evaluating concrete have been established and show great promise. However, much of the work is concerned with concrete piles or thick-walled specimen (greater than 500 mm). Vast amounts of concrete piping in sewer systems and water mains require testing techniques applicable to thinner-walled systems (less than 100 mm). This work aims to extend ultrasonic inspection techniques to thin-walled systems. Impact-echo and resonant ultrasonic spectroscopy (RUS) techniques are explored. Finite-element models have been developed to describe the propagation characteristics in different specimen. Several specimens have been tested experimentally to determine the effects of steel reinforcements, pipe curvature, and simulated defects. The influence of sensor configuration, transducer characterization, and data capture on measurement accuracy and inspection time is examined. The potential for wavelet analysis is explored for isolation of wave propagation modes and defect characterization.
High-frequency thermoviscoelastic vibration of functionally graded thin beams
Authors: Dokmeci M. Cengiz , Altay Glay
Published: October 2013

The paper presents the system of 1D equations so as to analyze the thermoviscoelastic behavior of an axially functionally graded beam of rectangular cross section at high-frequency vibration. First, the 3D fundamental equations of a hyperbolic thermoviscoelasticity are expressed by a unified variational principle in terms of the Laplace transformed field variables [cf., Dkmeci and Altay, Acta Mechanica 143, 91–11 (2000)]. Next, the temperature increment and the displacement field as well as the material density and elasticities [e.g., Sankar and Tzeng, AIAA J. 40, 1228–1232 (2002)] are expressed by the power series expansions in the thickness coordinate of the beam. A variational averaging procedure [e.g., Dokmeci and Altay, Int. J. Non-linear Mech. 37, 225–243 (2002)], together with the series expansions, is used in deriving the system of 1D beam equations in both differential and fully variational forms. The system of 1D equations governs the extensional, flexural, torsional, and thickness shear and also the coupled vibrations of the beam at high frequency. Special cases are indicated involving the material properties and/or the vibration of the beam. Also, the uniqueness is investigated in solutions of the system of beam equations. [Work supported by TUBA.]
A spike-based computational model for noise robust vowel classification
Authors: Uysal Ismail , Sathyendra Harsha , Harris John G.
Published: October 2013

The human ability to recognize speech drastically outperforms that of commercial ASR systems especially in noisy environments. Presently, there is limited knowledge of the auditory system dynamics, however it is known that coding and processing of information is carried out via action potentials. This research aims to better understand the coding mechanisms along the auditory pathway, while devising a noise robust system for speech recognition. A biologically plausible algorithm for vowel classification is proposed, which solely uses spikes for both the feature extraction and the classification stages. The algorithm uses an improved and adaptive model of the inner-hair cell [Sumner et al., J. Acoust. Soc. Am. 113, 893–901 (2003)] to generate spike trains at different characteristic frequencies. The synchrony among the hair cells is used as a noise robust means for feature extraction. Detected features are then classified using a spike-based rank order coder, which uses the spike arrival times to the postsynaptic neuron to encode information [Delorme and Thorpe, Neural Networks. 14, 795–803 (2001)]. Experiments on a noisy vowel dataset (5 dB SNR) show an average of 15% increase in the recognition rate for the prototype system when compared to a nearest-neighbor classifier employing Mel frequency cepstral coefficients.
Acoustic parameters for nasality based on a model of the auditory cortex
Authors: Pruthi Tarun , Espy-Wilson Carol Y.
Published: October 2013

Due to the longer length of the nasal tract as compared to the oral cavity, the asymmetry of the left and right nasal passages, and the coupling of the nasal tract to the sinuses, nasal sounds generally have more formants than oral sounds. However, all of the formants may not be prominent in the acoustic spectrum due to close-lying antiresonances. The net effect of the nasal peaks can be an increase in frequency modulation. In this work, we study the effectiveness of two new acoustic parameters (APs) that capture this increase in frequency modulation based on the ‘‘scale’’ dimension of a model of the auditory cortex [Chi et al., J. Acoust. Soc. Am. 118(2), 887–906 (2005)]. The new APs, mean center of gravity of scales and mean ratio of high scales to low scales, were used along with a previous set of four APs for the discrimination of nasal consonants and semivowels. Overall accuracy of 93.10% was obtained for this task. This corresponds to an 18.63% reduction in error rate over previously reported results. It remains to be seen if these APs are also useful in detecting nasalization in vowels. [Work supported by NSF Grant No. BCS0236707.]
Automated measurement of nasality over time in vowels
Authors: Berger Michael A. , Clayards Meghan , Bardhan Neil , McDonough Joyce
Published: October 2013

Nasalized vowels have acoustic characteristics that allow the degree of nasality to be quantified from the acoustic signal. These characteristics include decreased first-formant amplitude (A1) and increased amplitudes of two extra peaks (P0 and P1). Chen (1995, 1997, 2000) used the parameters A1−P1 and A1−P0 (dB) to quantify nasality in vowels. These two measures are complementary in that different vowel types may be more accessible to one or the other. This research attempts to extend Chen’s measures in several ways: (1) normalize the two parameters so that they are comparable; (2) integrate them into a single composite measure by a weighted average; (3) measure nasality over the time domain of each vowel token, resulting in nasality contours with high temporal resolution; and (4) automate the process of measuring nasality in vowels, so that large amounts of speech data can be processed rapidly by computer. Nasality measurement in this framework, whether manual or automated, requires a solution to the problem of tracking the three relevant peaks over time: F1, N0, and N1. A deterministic peak-tracking algorithm is proposed, but alternative statistical approaches are also considered. The validity of a peak-based approach for female speech is examined.
Information conveyed by f0 for vowel identification
Authors: Nearey Terrance M. , Assmann Peter F.
Published: October 2013

Our recent experiments with vocoded natural speech, wherein the spectral envelope and fundamental frequency are manipulated independently, have confirmed that some coordination of f0 and formant patterns are beneficial to vowel identification by humans. In an effort to model the perceptual dependency more precisely, we have investigated the performance of several alternative pattern recognition models on natural speech samples. This paper reports on several quite distinct methods of exploiting statistical relations between formant frequencies and f0 for recognition. Many of these methods yield quite similar results on the classic Peterson and Barney data and on larger, more recently collected data sets. Methods involving indirect normalization whereby the f0 of a single token is restricted to the role of estimating the formant frequency average of a speaker’s entire vowel system perform well. Indeed, they are often better than a method where the role of f0 is unconstrained, thus accommodating inherent pitch differences among vowels. The indirect use of f0 also allows for methods of combining f0 and formant range information in ways that preliminary results suggest to be more effective for modeling perceptual effects with modified stimuli. More formal evaluation against perceptual data will be presented.
Recurrence quantification analysis of speech
Authors: Schultz Aaron
Published: October 2013

A time-series analysis technique known as recurrence quantification analysis (RQA) holds promise as a new method for investigating the dynamical properties of the acoustic speech signal. RQA was created to deal with complex time series generated by high-dimensional, nonlinear dynamical systems. While RQA has most frequently been used for physiological studies and investigations into nonlinear dynamics, it has not been widely applied to the acoustic analysis of speech. Recurrence quantification analysis is free of many key assumptions involved in Fourier-type analyses such as data set size, stationarity, and linearity, which are routinely violated in the speech stream. This study offers some preliminary findings on the dynamic nature of speech and characteristics of speaker variability obtained by using recurrence quantification analysis. Future directions for the use of RQA in speech perception and production studies, including shadowing and imitation studies, are discussed.
Use of prior information in acoustic inference
Authors: Knuth Kevin H.
Published: October 2013

Often in scientific and engineering applications, we possess prior information about the specific problem under investigation. In acoustics, this prior information may consist of knowledge about the design and arrangement of our detectors, the behavior of the sound sources, and the laws of physics describing sound propagation through an intervening medium. In this talk I explore the use of prior information for use in Bayesian inference in acoustic applications. This prior information can be either encoded in the signal model, which is represented in the Bayesian formulation by the likelihood function, or in the prior probabilities, which weight the particular values of the signal model parameters. I give examples of the use of such prior information by focusing on the specific problems of source separation and localization. By choosing to focus on the appropriate model parameters one can change a source separation problem into a source localization problem and vice versa, thus changing the very nature of the acoustic inference.
Using the maximum entropy method to estimate probability density functions for oceanographic and acoustic parameters
Authors: Camin H. John , Culver R. Lee , Sibul Leon H. , Ballard Jeffrey A. , Jemmott Colin W.
Published: October 2013

The maximum entropy (MaxEnt) method offers a powerful means of estimating the probability density functions (pdf’s) of measured data. Traditionally, pdf’s have been estimated by fitting data to particular distributions (e.g., Gaussian, log-normal, Rayleigh, chi-squared, etc.). This approach can lead to misleading results, especially if the data are highly skewed or kurtotic. First published in 1957 by Jaynes [E. T. Jaynes, Phys. Rev., 106, 620–630 (1957)], MaxEnt has gained wide use in recent years. The method uses Lagrangian multipliers to maximize the entropy, a measure of uncertainty, subject to specified constraints. The result is a pdf that Jaynes describes as being the ‘‘least biased estimate possible on the given information; i.e., it is maximally noncommittal with regard to missing information.’’ In other words, all possibilities under the given constraints are considered equally. This method is particularly useful in determining prior pdf’s based on limited measurements. MaxEnt pdf’s, which belong in the exponential class of distributions, can also be used to derive optimum processors in the maximum likelihood sense. This talk will discuss the theory and implementation of the MaxEnt method and emphasize its utility for modeling acoustic propagation in uncertain environments. [Work supported by The Undersea Signal Processing Program, Office of Naval Research.]
Stochastic differential equation analysis for ocean acoustic energy scattering by internal waves
Authors: Morozov Andrey K. , Colosi John A.
Published: October 2013

Stochastic coupled mode theory is used to study acoustical scattering of a narrow-angle, low-frequency acoustical beam. Random index of refraction perturbation fields are described using the Garrett-Munk internal wave spectrum. The stochastic differential equations for the first- and second-order statistical moments of the acoustical field are derived using the Markov approach similar to Dozier, Tappert, and Chernov theories. The main objective of the research is to account for cross-mode correlations and to show that the method can be used for a calculation of the detailed structure of the mean acoustic field intensity distribution. For this purpose a narrow finite-frequency beam was taken as an example, and the intensity of the scattering field was calculated as a function of frequency and sound source depth. The coefficients of the matrix differential equation were obtained analytically, and an efficient numerical computation was obtained. Comparisons to Monte Carlo simulation show that the method can be used for detailed statistical sound field analysis in long-range propagation.
Effect of wind-generated surface waves on vertical coherence of sound propagation in the East China Sea
Authors: Yang Jie , Zhou Ji-Xun , Rogers Peter H.
Published: October 2013

Literature has shown that wind-generated surface waves are an important factor in determining the spatial coherence of long-range sound propagation [Kuperman and Ingenito, J. Acoust. Soc. Am. 113, 1178–1187 (1977); Zhou et al., J. Acout. Soc. Am. 115, 2550 (2004)]. During the ASIAEX in the East China Sea, wind speed and the rms waveheight were recorded between 29 May and 7 June along with acoustic measurements of broadband explosive sources. The rms surface waveheight varied between 0.1–0.6 m during the acoustic measurements. This paper analyzes the characteristics of vertical coherence of sound propagation under the influence of these surface waves. A model is built to explain observed characteristics of vertical coherence which incorporates coring analysis in the ASIAEX area. [Work supported by ONR.]
Propagation of modulated pulses in shallow water
Authors: Song Aijun , Badiey Mohsen , Katsnelson Boris , Tshoidze Alexander
Published: October 2013

In this paper propagation of low-frequency pulses, carrying information in shallow water, is studied. Different types of information-carrying pulses are analyzed and compared. These include phase shift keying (PSK) signals, frequency shift keying (FSK) signals, and noncoherent signals with respect to their ability to information transfer. Numerical modeling of pulses propagation is carried out. Basic attention is paid to studying the influence of dispersive characteristics of a shallow water channel (boundary conditions, variation of properties along the track, internal waves, etc.) on the waveguide capacity for different types of pulses and frequencies. Complex space-frequency and time-frequency intensity fluctuations of a propagating signal allow us to consider shallow water as the unique information channel (medium). A model for numerical calculations is constructed on the basis of the SWARM95 experimental data. [Work was supported by ONR and RFBR.]
The effect of turbulence and acoustic waves on underwater acoustic propagation
Authors: Wojcik Stefanie E. , Durgin William W. , Andreeva Tatiana A.
Published: October 2013

The primary objective of this study was to develop a predictive methodology for received signal variation as a function of ocean perturbations using a ray-based analysis of the effects of internal waves and ocean turbulence on underwater acoustic propagation. In the present formulation the eikonal equations are considered in the form of a second-order, nonlinear ordinary differential equation with harmonic excitation due to an internal wave. The harmonic excitation is taken imperfect, i.e., with a random phase modulation due to Gaussian white noise, accounting for both chaotic and stochastic behavior. Small scale and geostrophic turbulence are represented using the potential theory two-wave-number model for a vortex array. The focus is to numerically study the influence of these fluid velocity and sound speed fluctuations and the role of initial ray angle on underwater acoustic propagation to provide a realistic characterization of acoustic arrivals. Predicted arrival behavior is analyzed using ray trace, time-front, and phase plots for varying initial conditions. Regions of instability are identified using bifurcation and phase diagrams. This work leads to understanding how turbulence and internal waves affect sound transmission and utilizes the statistics of received signals to identify fluid mechanic phenomena that occurred along the sound channel.
Geometrical dispersion of broadband sound pulse in a three-dimensional shallow-water environment with a corrugated bottom
Authors: Sturm Frédéric
Published: October 2013

Numerical results of sound propagation in a three-dimensional oceanic waveguide with a sinusoidal (corrugated) bottom are reported. A broadband sound pulse with a center frequency of 25 Hz and a bandwith of 30 Hz is considered. This acoustic problem was studied by others considering a harmonic point source [M. D. Collins and S. A. Ching-Bing, J. Acoust. Soc. Am. 87(3), 1104–1109 (1990)]. The numerical method used to solve the 4-D acoustic problem is based on a Fourier synthesis of frequency-domain solutions. The calculations in 3-D are carried out using the fully 3-D parabolic equation based model 3DWAPE. To analyze the acoustic problem, we follow closely the methodology used in previous works to investigate the 3-D ASA wedge and the 3-D Gaussian canyon [F. Sturm, J. Acoust. Soc. Am. 117(3), 1058–1079 (2005)]. Results corresponding to a 25-Hz cw point source are first presented and compared with predictions by other models. Then, the acoustic problem is solved considering the broadband source pulse. The modal structure of the received signals on several distinct vertical arrays is analyzed and clearly exhibits mode arrivals of the propagating signal not predicted by pseudo-3-D or 2-D models.
John W. Kopec and The Sabines at Riverbank
Authors: Cavanaugh William
Published: October 2013

I first became acquainted with John Kopec at a meeting of the Greater Boston Chapter of ASA in the late 1970s. He told a delightful story of his discovery of papers of Wallace Sabine, long thought to be lost, at the IITRI Riverbank Acoustical Laboratories in Geneva, IL, where John had been an employee since 1961. John was working with Leo Beranek to have these papers donated to the Harvard Rare Books Library for safekeeping [L. L. Beranek, ‘‘The Notebooks of Wallace C. Sabine,’’ J. Acoust. Soc. Am. 61(3), (1977) L. L. Beranek and J. W. Kopec, ‘‘Wallace C. Sabine, acoustical consultant,’’ J. Acoust. Soc. Am. 59(1), (1981)]. I quickly learned that John had been collecting historical information on not only Wallace Sabine, but his cousin Paul Sabine, who was called upon to direct the laboratory in 1919 after Wallace’s untimely death, and Paul’s son Hale who also became director of the laboratory after Paul. It became obvious to all of us who heard John’s tales of Riverbank that he had to put these into print. Hence, at the urging of his abundant friends and colleagues, the Acoustical Society published The Sabines at Riverbank in 1997. This book is John’s legacy to all of us interested in the science of architectural acoustics and the part played by the Sabines at Riverbank.
Comparison of extended Kalman filtering with split-aperture processing for angle of arrival estimation in multibeam echo-sounding
Authors: Brogan Daniel S. , de Moustier Christian P.
Published: October 2013

Echo angle of arrival estimates may be obtained from the FFT beamformed output of a multibeam sonar system at each successive time sample. Whether tracking disparate targets in the water column or tracking a mostly continuous surface such as the seafloor, the sequence of angles of arrival versus time is inherently nonlinear and nonstationary, and lends itself to processing with an extended Kalman filter. This filter provides both an approximation of the optimum (in a least squares sense) angles of arrival estimation and a measure of the associated errors. This technique is applied to quadrature-sampled field data collected with the 26-element hydrophone array of a 160-kHz multibeam sonar system. Results are compared to arrival angle estimates obtained with a conventional split-aperture processor. [Work supported by NOAA Grant 111833.]
Adaptive predictive-error optimal gridding
Authors: Pflug Lisa A. , DelBalzo Donald R.
Published: October 2013

Transmission loss computations in littoral areas often require a dense spatial and azimuthal grid to achieve acceptable accuracy and detail. The computational cost of accurate predictions in complex areas can be unacceptable for some naval applications. EAGLE (Efficient Adaptive Gridder for Littoral Environments) was developed to reduce the computational requirements by adapting the fundamental calculation grid to the natural environmental structure. EAGLE produces a nonuniform grid structure within which the underlying data have approximately constant spatial uncertainty, or iso-deviance. The EAGLE point-selection approach is based on a predictive-error metric and least-squares polynomial curve fitting with arbitrary order. This research indicates the degree to which EAGLE grids are related to the underlying coherence properties of the natural environment. The results show significant efficiency enhancements compared to uniform grids of the same accuracy, when the environmental coherence properties are used to control the polynomial order. [Work sponsored by NAVAIR.]
``Flowers and Wreaths'': Radio theater and surround
Authors: White Ean
Published: October 2013

Originally produced in late 1992, ``Flowers and Wreaths'' is a setting for poems by Jacques Prvert (paroles Prvert) in French and in English translations by Lawrence Ferlinghetti and me. Prvert's success in France after World War II was largely due to his unabashed use of street language and his staunch antiwar, antirational political stance. The performance featured much original instrumentation: an amplified skull-resonator dental floss violone, a 35-ft.-long infrasonic electric monochord, a naval signal lamp, mechanized moving audience seating, the amplified electrocution of vegetables, unconventional speaker placement, etc. Mari Novotny-Jones and I continued to perform the piece through 1993. This new, surround recording is of only the title poem in the suite, ``Flowers and Wreaths,'' with a few elements which were originally used with other texts. It was a relatively quiet passage in an otherwise fairly raucous performance but was also a kind of spiritual center for the piece. The point of view for the listener during this extracted section is that of a corpse laying in a ditch by the side of a road. My intent is to explore the possibility of new, surround broadcast technology and its suitability for a resurgence of radio theater.
Moving Space
Authors: Oliveros Pauline
Published: October 2013

Moving Space (2006) is a composition for 5.1 surround sound system. Sustained sounds morph in quality as space changes and space changes as sounds move. The piece uses vector based amplitude panning (VBAP) and Monoverb mono implementation of the Schroeder/Moorer reverb model (mono version of freeverb∼) to achieve these changes. Sounds are improvised and processed by the expanded instrument system (EIS), a MAX program designed by the composer consisting of multiple delays and processing algorithms.
Rather the flight of the bird passing...
Authors: Plsek Thomas
Published: October 2013

Rather the flight of the bird passing... is a five-channel composition created to produce a surreal sound environment that could only exist in a recorded, multichannel version. The solo trombonist in the piece (the composer) performs and is recorded by 5 human mobile microphone stands, i.e., people holding microphones and moving around the recording space searching for sounds. The sounds and the movements are influenced by a poem by Alberto Caeiro (1889–1915), a poet who did not actually physically exist. He was a heteronym created by the great Portuguese poet Fernando Pessoa (1888–1935). Pessoa created numerous heteronyms, each with their own styles and subject matter. The line of the poem, ‘‘What’s past is nothing and remembering is not seeing,’’ is central to the practices used by all the performers to create the work.