bluuebunny/crossref_metadata_2025 huggingface dataset:
An accurate, efficient rough surface parabolic equation program
Authors: Rosenberg Allan P. , Magruder Steven F.
Published: October 2005

The parabolic equation program Fepe has been extended to handle a rough air–water interface treated as a series of stair steps. Because much finer vertical spacing may be needed to resolve the interface than to propagate an acoustic wave accurately in the rest of the domain, an option to use one vertical spacing near the surface and a coarser one in the rest of the ocean has been implemented. The necessary Galerkin approximations of derivatives on an unequally spaced grid have been worked out using the symbolic manipulation program Mathematica. A test case with a realistic surface is provided to demonstrate the accuracy of the new program Fepe–rsfc. The code is efficient enough to allow thousands of runs for realistic sized problems, for example to simulate the effect of a moving surface. [Work supported by the office of the Chief of Naval Operations.]
Propagation characteristics from the trans-Arctic propagation source as measured at a receiver in the Lincoln Sea
Authors: Lawrence Thomas N. , McCool Ilene , Bedford Nancy R.
Published: October 2005

The trans-Arctic propagation (TAP) source was a Russian device deployed north of Svalbard transmitting at about 20 Hz. Transmissions received in the Lincoln Sea north of Ellesmere Island were recorded on a 20-element vertical array located on the continental shelf. The propagation path between the source and receiver is over the Arctic Mid Ocean Ridge, then skirting the Morris Jesup Plateau, and finally propagating up the continental slope. The ice cover along this path of propagation is highly varied, ranging from central Arctic roughness levels (usually about 1–2.5 m standard deviation) to the higher roughness (about 4 m s.d.) of the Canadian Archipelago. Amplitude and phase fluctuations of signal and environmental noise over varied time periods, and the results for the statistical character of the water column will be presented. Comparisons will be made with modeled results to help determine the effects from this complex environment and to predict the impact of variation in ice conditions along the propagation path.
Mode vector parabolic equation
Authors: Abawi Ahmad T. , Kuperman W. A. , Collins Michael D. , Porter Michael B.
Published: October 2005

A mode vector parabolic equation (MVPE) is derived for the propagation of normal modes in the ocean waveguide. This model, which includes mode coupling, is a generalization of the adiabatic mode PE [M. D. Collins, 2269 (1993)]. The main features of this model are: (1) It is based on an initial value differential equation which propagates normal modes rather than a method that involves matching solutions at interfaces. (2) The solution vector whose components are the amplitude of the modes is not derived from a procedure involving a reference wave number and thus each vector component is locally accurate around each mode. (3) It agrees with previous benchmark solutions. (4) The model is tractable in three dimensions. MVPE has three parts: Spatial derivative of the mode amplitudes, eigenvalue, and coupling coefficients matrices. The latter two are precomputed; the coupling matrix is based on McDonald’s formulation in terms of environmental parameters which is summarized in [McDonald etal., 2357 (1994)]. The system of equations can either be solved by matrix inversion or iteration. To illustrate the method, the solution to the problem of propagation of waves in a two-dimensional wedge is presented in detail.
Application of the mode vector parabolic equation to the 3-dimensional wedge problem
Authors: Abawi Ahmad T. , Kuperman W. A.
Published: October 2005

The MVPE [Abawi etal., this session] is applied to the problem of propagation of waves in a 3-dimensional coastal wedge and the results are compared with those when horizontal coupling is neglected and with the results obtained from conventional 3-dimensional methods. The components of the solution vector are the amplitudes of the vertical modes which are coupled in both range and azimuth. The coupling matrices for both range and azimuth are precomputed by the method summarized in [McDonald etal., 2357 (1994)]. In the absence of mode coupling, the solution reduces to the solution of the adiabatic mode parabolic equation [M. D. Collins, 2269 (1993)]. The system of equations are numerically solved by the Crank–Nicholson finite difference method. For a single vertical mode, this system of equations closely resembles a system of discretized parabolic equation in range and azimuth. For multiple modes, the matrices involved are band diagonal with the coupling matrices appearing in their diagonal. The size of these matrices are thus equal to the number of points in azimuth times the number of vertical modes. When the physics of the problem is contained in a subset of coupled modes, this method offers additional advantages in numerical computation over the conventional 3-dimensional methods.
A neural basis for the synthesis of sound, sight, and touch
Authors: Stein Barry E.
Published: October 2005

That visual cues affect speech perception has been known for some time, but is only one part of the much broader phenomenon of cross-modal integration. This fundamental characteristic of the CNS has a profound influence on perception and behavior and is evident not only in speech perception, but in the facilitated detection, identification, and reaction to combinations of concordant cues from different modalities, and in the striking perceptual anomalies that can occur when these cues are discordant. Understanding the mechanisms by which these functions are achieved requires a fundamental knowledge of the neural bases of multisensory integration; specifically, the circuits involved and the principles by which such ‘‘multisensory’’ neurons synthesize their convergent sensory information. Perhaps the best known site of multisensory convergence is the superior colliculus, a midbrain structure involved in attentive and orientation functions. The spatial, temporal, and receptive field characteristics of its constituent multisensory neurons serve as an excellent model for understanding the neural principles of multisensory integration throughout the CNS and for predicting overt behavior. It will be these multisensory circuits, the neural principles by which they affect multisensory integration, and the impact of this integration on overt behavior which will be emphasized in this discussion.
Unisensory and multisensory convergence in a phonetotopic register
Authors: Remez Robert E.
Published: October 2005

Descriptive studies have noted that speech perception is ineluctably multisensory if the listener can hear and see the talker. In such cases, the resolution of linguistic attributes occurs by combining auditory and visual inflow rather than by phonetic analyses in each modality before convergence. Because subjects readily acquire unanticipated proficiency in haptic and auditory integration, some researchers have conceptualized speech perception as a multisensory means of detecting a talker’s phonetic production, independent of memorized sensory prototypes. These findings have motivated a definition of the problem of sensory convergence in terms that are literally multisensory: How do auditory and visual and haptic afferents coalesce? Recent studies of perceptual organization in a speech mode present a contrasting view, based on a phenomenon of unimodal convergence in speech perception. In this research employing tonal analogs of speech signals, phonetic perception occurs if auditory constituents cohere. Failure of convergence in this empirical paradigm is equal to failure of phonetic perception. Together, these studies suggest that integration of sensory attributes in speech perception is equivalent across changes in domain, from uni- to multisensory, and warrants an account of convergence that is general over changes in the scale of the sensory projection. [Work supported by NIDCD.]
15 minutes of chaos
Authors: Korman Murray S. , Crum Lawrence A.
Published: October 2005

Apparatus (both mechanical and electrical) will be presented to illustrate the complexities of a certain nonlinear behavior termed as chaos. In this demonstration, you will see a ‘‘chaos man’’ (a store bought sticklike compound pendulum) oscillate with a very complex motion. A simple pendulum will be made to oscillate (inverted) with the pivot at the bottom and the mass at the top. An electric circuit (modeling a nonlinear mechanical system) will be used to demonstrate chaotic behavior—which occurs when the system is driven with sufficient amplitude at certain frequencies.
How a wind instrument makes a sound
Authors: Hoekje Peter L.
Published: October 2005

Two demonstrations illustrate the mechanism of sound production in musical wind instruments. First, a ‘‘water trumpet’’ inspired by A. H. Benade produces waves in a water-filled trough. The wave action is generated at one end of the trough by a feedback valve which regulates the inlet flow of water according to the height of the water waves at that same end of the trough. This is analogous to the generation of sound in lip reed brass instruments and cane reed woodwinds in which the flow of air through the reed valve is affected by the pressure inside the instrument mouthpiece. The second demonstration again mimics the feedback mechanism of the reed with a simple electronic device which allows a wind instrument to sound itself. The air in the mouthpiece is excited by a small speaker which is driven by an amplified signal from a microphone sensing the pressure in the mouthpiece. The playing frequency depends on the resonances of the instrument and corresponds to a normal note of the instrument. Thus the demonstrator can finger a scale on the instrument and the instrument will play along.
Statistical methods for automated INM path derivation
Authors: Flynn David A.
Published: October 2005

Flight paths at an airport can be viewed as samples of a statistical distribution. An individual sample path xi, is described by the position as a function of distance from the airport. The mean paths of distribution 〈xm〉 minimize Σxi−〈xclosest〉, where the operator ‘‘−’’ is an approximation of the difference in ground noise projection of two paths, and ‘‘m’’ is the desired number of mean paths. Cluster analysis methods can be used to find this set of mean paths: they will by definition be the optimal m paths for use in the INM in place of the original sample paths. These methods can reduce hundreds of thousands of radar monitored paths into a concise set of INM tracks. Moreover, they do not suffer measurement anomalies that gate penetration analysis suffers.
Modeling aircraft departure profile using ARTS radar data
Authors: Dunholter Paul
Published: October 2005

The current method for the modeling of aircraft departure profiles is to use the standard departure profiles contained in the INM noise model. The INM model accounts for the different departure gradients based upon the flight distance to the aircraft’s destination. Aircraft flying a longer distance are assumed to be heavier and as a result, would climb at a lower gradient. New techniques involve using the actual flight profiles from the FAA’s ARTS radar data. State-of-the-art airport noise monitoring systems collect flight track data [Aircraftidentification, Typeofoperation, andaircraftposition (X, YandZ)] from the ARTS data. This information can be processed to determine the actual flight profiles for each aircaft type as well as a range of profiles for a specific aircraft. Using this technique, the departure profiles used in the model account for not only the departure distance, but also pilot techniques, the actual aircraft load as well as meteorological conditions such as altitude, density, and wind speed. The result is that the modeling of aircraft departure flight profiles are based upon actual data specific to the flights and conditions at the airport under study.
Use of flight track information to resolve individual and community-wide aircraft noise concerns
Authors: Robertson Karen L.
Published: October 2005

Technological advances in airport noise monitoring systems have provided the ‘‘missing link’’ of data needed to manage an airport noise office effectively. The addition of aircraft flight track and altitude information has given airport proprietors the necessary tools to understand, if not alleviate, certain community concerns regarding aircraft noise and overflights. Airport neighbors often contact the local airport or FAA office when an aircraft operation is annoying. The annoyance may be a result of one, or many, concerns ranging from noise to aircraft flight patterns to overall safety. Once concerns are voiced, airport neighbors want immediate information regarding the annoying event, followed by the ever-allusive ‘‘corrective action.’’ Specific examples of how the new generation airport noise monitoring and flight tracking systems can respond to community or individual concerns will be demonstrated in an interactive format, followed by innovative, intriguing uses for the system. Information from these systems can surprise even the most knowledgeable airspace analyst or airport noise official.
Classification of noise events as aircraft overflights by means of one-third octave band algorithms
Authors: Sneddon Matthew
Published: October 2005

A set of algorithms for real time classification of noise events as low altitude military aircraft overflights was developed for use in a personal noise monitoring system. The classification algorithms, which are applied to polynomial curve fits to time series of sound pressure level measurements rather than to raw data, operate primarily on the temporal symmetry and relative rates of increase and decrease of sound levels in different one-third octave bands. Correct classification performance and misclassification errors vary with disjunctive decision rules applied to the outputs of the algorithms. [Work supported in part by the U.S. Air Force NSBIT program.]
Six months of continuous measurement of one-hour average sound levels, one mile sidewise from NAS Miramar, San Diego
Authors: Young Robert W.
Published: October 2005

From 18 July 1994 to 17 December 1994, 1-h average sound level was measured continuously by Computer Engineering Ltd. model 493 integrating sound level meter feeding model 238A secondary processor. The time-mean-square average level printed automatically on the hour, and recorded in an RS232C memory for later analysis, is that during the hour preceeding the hour printed. The site of noise monitoring is the roof 7084 Miramar Road, San Diego, about a mile sidewise north of Runway 6L-24R, NAS Miramar. After adjustments to remove steady ventilating and compressor noise, aircraft noise was tabulated for each day as community noise equivalent level (CNEL), the day-evening-night weighted 24-h average level specified for California airports. The 148-day average CNEL was 69 dB. In one week CNEL varied from 58 dB on Sunday to 75 dB on Tuesday. Such noise variability is being investigated in relation to future movement of Navy aircraft from Miramar to NAS Lemoore, and Marine aircraft from MCAS El Toro to Miramar. Also being here reported for 7084 Miramar Road are the A-weighted sound exposure levels (ASEL) in excess of 100 dB; the greatest thus far is 116 dB.
The SEL noise reduction provided by barriers to residences located near runway ends
Authors: Avillez Marcio
Published: October 2005

The T.F. Green State Airport in Warwick, Rhode Island, has a noise barrier intended to reduce noise at residences on one side of Runway 05, near the start of the takeoff roll. Measurements were conducted to evaluate the attenuation provided by the barrier. This was accomplished by selecting pairs of measurement positions that were located on opposite sides of the runway and equidistant from the centerline of the runway. The measurement results indicate that barriers can significantly reduce SEL of departing aircraft, and consequently the DNL, at residences located near the end of a runway.
The measurement of target strength of complex underwater structures—The early years
Authors: Niemiec Jan M.
Published: October 2005

By the early 1970’s, few measurements of target strength of large scale underwater structures had been made. Novel measurement techniques to control the range, depth, and aspect angle of the underwater target had to be developed. Unique instrumentation had to be devised to measure the incident sound level at the target and to reliably record the scattered sound wave on a ping by ping basis without interrupting the rotating target. Dr. Wayne Reader lead a group of scientists and engineers who successfully overcame many of these difficulties and measured the target strength of a large scale model of a complex structure known as KAMLOOPS. In addition to providing the leadership for the resolution of many technical problems, Wayne Reader developed a unique method to calibrate the scattering measurements by using the doubly curved surface of the KAMLOOPS dome as a standard target. Many of the measurement techniques pioneered by Wayne are still in use today. This talk outlines the aspects of a model target strength measurement and illustrates some of the many contributions that Wayne made to this field of science.
Sonar baffles
Authors: Radlinski Ronald P.
Published: October 2005

Acoustic decoupling baffles are often used to minimize noise contamination at hydrophone and transducer arrays. To maintain sensitivity near the nominally pressure release surface of the baffle, hydrophones can be placed at an odd multiple of a quarter wavelength from the baffle or near a heavy signal conditioning plate inserted between the hydrophones and the baffle. In either case, coherent interference between the incident wave and the wave reflected from the baffle limits the bandwidth of high sensitivity. Wayne Reader reasoned that by inserting a broadband absorber between the hydrophones and the decoupling baffle, a smoother hydrophone response could be attained of potentially less weight with relatively small loss in sensitivity. The talk describes the use of gradual transition absorbers developed by Wayne for sonar applications and his interactions with the author to combine these materials with broadband decouplers such as arrays of compliant tubes. His careful and thoughtful approach to the theoretical and experimental aspects of acoustic and material research was inspirational and we miss his insight, advice, and encouragement.
Wayne T. Reader: The Vector Research Company years, 1988–1994
Authors: Vest C. Warren
Published: October 2005

After 30 years of distinguished government service Dr. Wayne T. Reader retired in 1988 and joined Vector Research Co., Inc. as principal research scientist. He continued his Navy-sponsored anechoic materials research program. He recruited a talented research and development team and established a state-of-the-art dynamic material evaluation laboratory. He developed unique experimental procedures for evaluating static and dynamic properties of viscoelastic materials, an extensive material properties database, and analytical computer programs to predict acoustic performance of layered media including anechoic lining systems. He continued to seek economical solutions to acoustic quieting and won a competitive Navy procurement to design and install an innovative lining system to a large anechoic test tank. While continuing his work with passive voided polymers, he began exploring the advantages of composites containing discrete and distributed piezoelectric particles in a polyurethane medium. In addition to his technical work, Wayne Reader established a working environment which met not only his interests but also the company’s and the Navy’s as well. He attracted and mentored several young scientists who continue to work in this field.
The development of 1–3 piezocomposite materials for large-area actuator applications
Authors: Ting Robert Y.
Published: October 2005

One of the technical subjects to which the late Dr. Wayne Reader made a significant contribution in recent years was the development of 1–3 piezoelectric composite materials, which consist of thin ceramic rods aligned and embedded in a polymeric matrix. The combination of good piezoelectric properties and the potential of low-cost manufacturing for large area coverage makes this new class of composite materials attractive for application as large area actuators in vibration control. Some of Dr. Reader’s work will be reviewed, and the most recent development of new 1–3 piezocomposites will be discussed. Special new fabrication methods and the resulting material will be introduced. Acoustical properties of these new samples have been evaluated as a function of pressure and temperature and some of the results will be reported in this presentation.
History and status of working group S2-79 on the characterization of the dynamic properties of viscoelastic polymers
Authors: Hartmann Bruce
Published: October 2005

Recognizing a long-standing need for standard materials to calibrate acoustic measurement equipment, Wayne Reader initiated a Working Group with the title ‘‘Characterization of the Dynamic Properties of Viscoelastic Polymers.’’ The Working Group was organized under Standards Committee S2 of the Acoustical Society of America and was given the designation S2-79. The desirable qualities for the materials were: Ready availability, wide range of acoustic properties, stable with time, reproducible from lot to lot, and thermorheologically simple. He drew Group members from government, private industry, and universities, both in this country and abroad. Under his leadership, the Working Group progressed to the point that its work is nearly complete. This presentation will give an overview of the results from various laboratories on the most promising candidates. Emphasis will be given to a high loss polyurethane, for which the most data is available. In contrast, data for a low loss polyurethane will be presented to illustrate the reasons it was eliminated as a standard.
A technique for measuring the reflectivity of panels at low frequencies and high oblique angles
Authors: Dlubac J. J. , Deigan R. J.
Published: October 2005

Conventional short-pulse techniques for measuring the reflectivity of acoustic panels require that the reflected and incident waves be separated in time so that their ratio can be established. This technique is limited to moderate angles of incidence, since at high angles the direct and reflected waves overlap. An interference method is investigated as a way of making reflectivity measurements at high oblique angles. The total field (incident and reflected) near an oblique panel is measured relative to the incident field without the panel. The total field, which depends on frequency and angle of incidence as well as the panel material, is then examined and manipulated to extract information on the reflected wave. The technique is demonstrated with data reduced on steel plates.
The design and development of an anechoic lining system for the acoustic test facility at NUWC Newport
Authors: Emery N. Scott , Peña Lois , Satyapal Shanti , Ng Kin , Sauter David
Published: October 2005

During his years at Vector Research Company, Inc., Dr. Wayne T. Reader applied his extensive knowledge and experience in absorptive and decoupling coatings to the design and development of anechoic lining systems for large acoustic test tanks. The result of Dr. Reader’s efforts was the award of a competitive Navy procurement to Vector to design and install a broad frequency (1 to 100 kHz) anechoic lining system in the acoustic test facility (ATF) and NUWC Newport. Based on Dr. Reader’s designs and concepts, a prototype anechoic lining system for the ATF and NUWC Newport was tested successfully and the full system will be installed in the Spring of 1995. Background on the design and development of the lining system and data from prototype testing will be presented.
Results of recent development to measure and analyze the dynamic properties of materials
Authors: Nashif Ahid
Published: October 2005

Although the vibrating beam technique has been widely used and demonstrated to be an effective technique for measuring the dynamic properties of materials, it has its own limitations. This is because the present analysis uses the fourth-order beam equations which do not adequately handle the boundary conditions of the test specimens especially for the fundamental mode of vibration. Because of that, measurements on the first and sometimes the second modes of vibration have been omitted which limits the frequency range where measurements could be made. To overcome such limitations, a new approach using finite element analysis has been developed to compute the dynamic properties of materials for several modes of vibration, including the lower ones. This analysis is suited for either extensional or shear deformation, depending on the geometry of the specimen. Results of using this analysis to compute the dynamic properties of the various proposed materials for the S2WG79 standard will be presented and discussed.
Flow-induced self-noise on a spherical sensor
Authors: Jones Andrew R. , Lauchle Gerald C.
Published: October 2005

An experimental effort to characterize the low Reynolds number flow-induced self-noise on a spherically shaped inertial sensor operating underwater is described. The transducer is a small geophone encased in a sphere, 76.2 mm in diameter. The sphere itself is cast from a 4:1 by volume of polystyrene microballons and epoxy resin, which yields a slightly negatively buoyant bluff body that is capable of sensing weak fluctuations in velocity such as those resulting from acoustic disturbances. When such a sensor is used in ocean environments, a spurious self-noise signal oftentimes exists due to low velocity currents. The research described in this paper quantifies this flow-induced noise signal as a function of the sphere diameter Reynolds number (0<Red<20 000) and it is found that the broadband (10 to 1000 Hz) flow-induced signal is due to the turbulent flow structures shed by the sphere. Virtually no broadband noise is produced when the Reynolds number is subcritical and the shed vortices are laminar. [Work supported by Naval Air Warfare Center, Warminster, PA under ONR contract.]
Measures of auditory-visual integration
Authors: Grant Ken W. , Clay John L. , Walden Brian E.
Published: October 2005

The easiest and most effective way to improve speech recognition for hearing-impaired individuals, or for normal-hearing individuals listening in noisy or reverberant environments, is to have them watch the talker’s face. Auditory-visual (AV) speech recognition has been shown consistently to be better than either hearing alone or speechreading alone for all but the most profoundly hearing-impaired individuals. When AV recognition is less than perfect, several factors need to be considered. The most obvious of these are poor auditory (A) and poor visual (V) speech recognition skills. However, even when differences in unimodal skill levels are taken into account, differences among individual AV recognition scores persist. At least part of these individual differences may be attributable to differing abilities to integrate A and V cues. Unfortunately, there is no widely accepted measure of AV integration ability. Recent models of AV integration offer a quantitative means for estimating individual integration abilities for phoneme recognition. In this study, we compare several possible integration measures, along with model predictions, using both congruent and discrepant AV phoneme and sentence recognition tasks. The focus of this talk will address the need for independent measures of AV integration for individual subjects. [Work supported by NIH Grant DC00792.]
Perceiving talking faces
Authors: Massaro Dominic W. , Cohen Michael M.
Published: October 2005

Speech perception has been studied extensively in the last decades. It has been learned that people use many sources of information in perceiving and understanding speech. This talk focuses on the important contribution of visible information given in the talker’s face in face-to-face communication. This visible speech is particularly helpful when the auditory speech is degraded due to noise, bandwidth filtering, or hearing impairment. Although the influence of visible speech is substantial when auditory speech is degraded, visible speech also contributes to performance even when paired with intelligible speech sounds. The importance of visible speech is most directly observed when conflicting visible speech is presented with intelligible auditory speech. These studies use a synthetic talking face to achieve control over the visible speech and to study those visible aspects that are informative. The talking head can be heard, communicates paralinguistic as well as linguistic information, and is controlled by a text-to-speech system. A fuzzy logical model of perception (FLMP) has been shown to provide an accurate description of how people evaluate and integrate audible and visible speech in a broad range of experimental studies. Demonstrations of the talking head and various psychological phenomena will be provided. [Work supported by NIDCD.]
How musical instruments make sound
Authors: Rossing Thomas D.
Published: October 2005

Simple demonstration experiments help us understand how bars, membranes, plates, and air columns vibrate and how they produce musical sound. They also help us understand the physics of vibrations and waves.
A lecture demonstration of the cochlea
Authors: Keolian Robert M.
Published: October 2005

Part of the mystery of the cochlea, the organ of hearing in mammals, is how it distinguishes different frequencies from one another so well. Even though the cochlea is small, filled with fluid, and made out of tissue, its frequency selectivity corresponds to a quality factor Q which is quite high—about 300. Part of the answer lies with an unusual traveling wave that deposits the energy of different frequencies at different positions. This will be shown with a lecture demonstration that displays the physics of this wave.
The prediction of sonic-boom distortion using a scattering center based calculation
Authors: Raspet Richard , Bass Henry E.
Published: October 2005

A numerical scattering technique has been developed to calculate the effect of turbulence on sound propagation. This technique resolves the atmosphere into discrete ‘‘turbules,’’ calculates the scattered field from each turbule using the Born approximation, then sums all the contributions to form the scattered waveform. The effect of single ‘‘turbules’’ of different scales will be discussed. This technique has been applied to model the atmosphere and the propagation of sonic booms through the planetary boundary layer during the JAPE-2 tests at White Sands. Good agreement was achieved. The limitations and planned improvements will be described. [Work supported by NASA Langley Research Center.]
Acoustic scattering from bodies: Range of validity of the deformed cylinder method
Authors: Partridge Chris , Smith Edgar R.
Published: October 2005

The deformed cylinder method is a very versatile model that can be used on a wide range of acoustic scattering problems. It may be applied to any axisymmetric body, whether it be rigid, an elastic solid, or a shell. Previous results obtained from this model have been restricted to broadside backscattering. This work is the first to verify the validity of the deformed cylinder method over such a wide range of shapes and material properties for angles close to broadside incidence. In order to determine the angular range from broadside over which the deformed cylinder method is valid, these estimates are compared with approximations from other techniques currently available. Agreement at angles of up to 30° from broadside was obtained for the rigid targets considered. The paper also shows that the deformed cylinder method produces reasonable levels for solid elastic bodies for up to 10° to 20° off normal incidence.
Variability in the production of quantal vowels revisited
Authors: Beckman Mary E. , Jung Tzyy-Ping , Lee Sook-hyang , de Jong Kenneth , Krishnamurthy Ashok K. , Ahalt Stanley C. , Cohen K. Bretonnel , Collins Michael J.
Published: October 2005

Articulatory and acoustic variability in the production of five American English vowels was examined. The data were movement records for selected fleshpoints on the midsagittal tongue surface, recorded using the x-ray microbeam. An algorithm for nonlinearly transforming fleshpoint positions to a new Cartesian space in which the x and y axes represent, respectively, the distance of the fleshpoint along the opposing vocal tract wall and the distance perpendicular to the tract wall, is described. The transformation facilitates a test of Quantal Theory in which variability in the two dimensions is compared over many productions of a given vowel type. The data provide some support for the theory. For fleshpoints near ‘‘quantal’’ constriction sites, the primary variability was in the x dimension (constriction location). The y-dimension values were more tightly constrained, and the formant frequencies were more significantly correlated with the y values than with the x values. The greater variability in constriction location than in degree was not an artifact of the greater distances traversed in the x dimension between the vowel and constrictions in neighboring consonants, since the pattern was preserved when pellet values were translated to take into account a ‘‘context-free’’ vowel target (the average values in the context of preceding and following labial consonants). Moreover, the observed correlations between formant values and pellet positions in the two dimensions for [i] and [u] were duplicated in an articulatory-to-acoustic modeling test using values for constriction length and cross-sectional area estimated from the data. The model showed smaller second formant variability in the x dimension than in the y dimension for equal-sized excursions near the constriction sites for these close vowels, in keeping with the interpretation that speakers exercise less precise control in just the dimensions and regions where quantal stability is available. However, the articulatory pattern was seen not just in vowels which clearly have consonantlike constrictions (the quantal vowels [i], [u], and [ɑ ]), but also in nonquantal vowels such as [æ].
Thickness shear vibrations of a circular cylindrical piezoelectric shell
Authors: Yang J. S. , Batra R. C.
Published: October 2005

Axial and tangential thickness shear vibrations of a circular cylindrical piezoelectric shell of monoclinic crystals are studied. The problems are solved analytically, and the frequency equations are derived. For a cylinder made of a rotated Y-cut quartz, the resonant frequencies are computed numerically, and it is shown that they approach that of a flat plate as the inner radius of the cylinder of finite thickness approaches infinity.
High-temperature fiber-optic lever microphone
Authors: Zuckerwar Allan J. , Cuomo Frank W. , Nguyen Trung D. , Rizzi Stephen A. , Clevenson Sherman A.
Published: October 2005

The design and construction of a fiber-optic lever microphone, capable of operating continuously at temperatures up to 538 °C (1000 °F), are described. The design is based on the theoretical sensitivities of each of the microphone system components, namely, a cartridge containing a stretched membrane, an optical fiber probe, and an optoelectronic amplifier. Laboratory calibrations include the pistonphone sensitivity and harmonic distortion at ambient temperature, and frequency response, background noise, and optical power transmission at both ambient and elevated temperatures. A field test in the Thermal Acoustic Fatigue Apparatus at Langley Research Center, in which the microphone was subjected to overall sound-pressure levels in the range of 130–160 dB and at temperatures from ambient to 538 °C, revealed good agreement with a standard probe microphone.
Efficient acoustic-field computations for matched-field inversion for geoacoustic properties
Authors: Dosso S. E. , Chapman N. R. , Racca R. G. , Henson N. G.
Published: October 2005

Matched-field inversion for source location, environmental properties, or a combination of the two (focalization) is based on comparing measured acoustic fields to replica fields predicted for a variety of possible environmental parameters and/or source positions using a numerical propagation model. Although this approach is conceptually straightforward and widely applicable, it requires a large number of replica-field computations and can be impractically slow if the propagation modeling is not carried out in an efficient manner. This is particularly true for environmental inversion and focalization where the expanded parameter search space generally requires a very large number of replica field computations, even if a relatively efficient optimization algorithm such as simulated annealing (SA) is employed. This paper describes matched-field inversion for geoacoustic properties using SA and rapid acoustic-field modeling. The replica-field modeling is based on the normal mode solution and makes use of multivariate interpolation of precomputed ‘‘look-up’’ tables of modal quantities stored as a function of the geoacoustic parameters. The optimum grid-element size for the modal tables is considered, and two interpolation schemes, linear and Shepard’s method (locally quadratic), are investigated. An example is given of geoacoustic inversion in a North Pacific environment.
Depth-dependent gas fractions in acoustic models of marine sediments
Authors: Boyle Frank A. , Chotiros Nicholas P.
Published: October 2005

Models have recently been developed for acoustic scattering from trapped gas bubbles in sandy and silty marine sediments [F. A. Boyle and N. P. Chotiros, 3219 (A) (1994) and F. A. Boyle and N. P. Chotiros, 1766 (A) (1993)]. These preliminary models may be somewhat limited in applicability due to an assumption that the bubbles are distributed homogeneously throughout the half-space below the sediment interface. Observations suggest that actual sediments are horizontally stratified, and that gas fractions have strong depth dependence. The models have therefore been modified to allow specification of a depth-dependent gas fraction. Studies suggest that the backscattering strength is significantly affected, with considerable influence on its grazing angle dependence. [Work supported by Naval Research Laboratory, Stennis Space Center under the MCM Tactical Environmental Data System (MTEDS) project.]
Time-frequency analysis techniques exploiting the harmonic relationships of outside sound source emissions, for the purpose of detection and classification
Authors: Mossing John C. , Karim Mohammad A.
Published: October 2005

Acoustic sensors can be used to passively detect, track, and identify non-line-of-sight sound sources. The sound sources discussed in this paper contain strong harmonic components and range from being ‘‘pseudo’’ stationary to transient in nature. This research project investigates the use of various time-frequency analysis techniques for the purpose of selecting features to be extracted from the acoustic signatures of motorized sound sources. Acoustic data were filtered and digitized using a commercially available analog-digital convertor. The short time Fourier transform (STFT) was used as the initial identifier, followed by narrow-band peak detection algorithms used to select peaks above a user defined SNR. When sufficient ‘‘nonsmeared’’ peaks exist, these peaks are used to generate a set of harmonically related features which are input to a bayesian quadratic classifier. When the signal became more ‘‘nonstationary’’ and the use of the STFT resulted in excessive ‘‘smearing,’’ wavelet and Wigner-Ville analysis technique were employed. Results are presented highlighting the trade-offs of these time-frequency analysis techniques. Additional results are presented discussing the harmonic relationship algorithm employed to normalize the frequency shifts (due to rotor/engine RPM fluctuations) which exist in this type of signature data.
Fast inversion of the ill-conditioned shallow water propagation operator for pulsed signals
Authors: Roginsky Jacob , Stewart G. W.
Published: October 2005

Time series deconvolution in underwater acoustics is a difficult problem due to the practically singular nature of the propagation operator. The situation is even more complicated in the presence of a multipath environment. In particular, when the time window is shorter than the propagation time, the process requires the solution of a large triangular Toeplitz system that is quite ill conditioned. Satisfactory results can be obtained by truncating the singular value decomposition (SVD), but only at the cost of ignoring the Toeplitz structure. The object of this work was to investigate the alternative of using Tichonov–Phillips regularization to lessen the effects of the ill conditioning. An algorithm of Lars Eldén [SIAM J. Sci. Stat. Comput. 5, 229–236 (1984)] that takes advantage of the Toeplitz structure can be adapted to this purpose. The results are as good as those obtained from the SVD, but the cost is O(n2) in the matrix size as opposed to O(n3) for the SVD. For the problems considered here, this amounts to a speedup of two orders of magnitude.
Animations of pulse signals scattering from submerged resonating structures
Authors: Werby M. F. , Sidorovskaia N. A.
Published: October 2005

A formulation that allows one to describe scattering from objects in a waveguide has been developed. The method is based on coupling the free-field T-matrix to a waveguide using the normal mode code SWAMP and the T-matrix codes developed at NRL. This formulation allows for the rapid reproduction of solutions and allows one to replicate pulse scattering from resonating objects in a waveguide. Animations of signals scattering from resonating objects is presented. The results are shown to enhance insight into the physics of such scattering processes.
Effects of bow-hair compliance on bowed-string motion
Authors: Pitteroff Roland , Woodhouse James
Published: October 2005

Bow–hair compliance is likely to have a strong effect on bow–string interaction. The first line of evidence comes from analyzing experimental results presented by Cremer [L. Cremer, ThePhysicsoftheViolin (MIT, Cambridge, MA, 1985)] of the reflection and transmission behavior of transverse waves on a string incident on a bow atrest. The second line of evidence comes from simulations of the bowed string taking into account the finite width of the bow. The nature of the ‘‘differential slipping’’ which may arise due to the kinematical incompatibility of uniform bow velocity across the width of the bow and the string velocity in standard bowed-string motion (Helmholtz motion) is strongly dependent on bow–hair compliance. Simulations also demonstrate that suitable tilting of the bow can reduce the extent to which ‘‘differential slipping’’ is detrimental to the establishment of the desired string motion. Preliminary results of an experimental investigation of finite bow-width effects will be discussed.
Concurrent amplitude modulation detection with two carriers
Authors: Sheft Stanley , Yost William A.
Published: October 2005

The ability to detect amplitude modulation (AM) of two concurrent tonal carriers was measured in a 4 AFC task; each carrier was independently modulated during one of two observation intervals. Carrier frequencies were 700 and 2350 Hz and AM rates were 4, 16, and 200 Hz. In the concurrent detection task, the modulation depths were either 1.0 or set for a detection d’ of 0.7 or 2.0 with modulation of just one carrier. Results showed large performance decrements in the concurrent detection procedure that were greater than typically obtained in other two-channel listening tasks. Partitioning of the 4×4 response matrix indicated interaction between carrier channels with performance generally better when both tones were simultaneously modulated and for most subjects at the greater modulation depths when both responses were correct. Cross-channel estimates of correlation derived from the bivariate normal distribution were highly dependent on the subject’s response strategy. When both tones were modulated at the same rate, results are consistent with past work indicating difficulty associating modulation with its appropriate carrier. Overall results indicate limited ability to independently process two concurrent sources of modulation information. [Work supported by NIH.]
Psychophysics of speech perception: What critical data are needed to improve low bit-rate-coding and automatic recognition?
Authors: Ghitza Oded
Published: October 2005

The purpose of this special session is to call the attention of the hearing science community to the need for new knowledge on how speech segments of durations of 50–150 ms long (e.g., phonemes, diphones), are being represented in the auditory system. In this session, the need for such knowledge will be addressed in the context of two specific speech-technology applications—low bit-rate coding and automatic recognition (ASR)—which rely on processing speech information of a segment-length duration. Schemes for low bit-rate coding rely on signal manipulations that spread over durations of several tens of ms, and schemes for speech recognition rely on phonemic/articulatory information that extends over similar time intervals. Current research efforts are focused on the psychophysics of stationary acoustic inputs, for example, aspects of masking, pitch perception, and sound segregation. Research efforts also exist on the cognitive aspects of speech perception, for example, lexical access. In contrast, research on the psychophysical aspects of speech dynamics, as manifested in the acoustic properties over durations of tens of ms, still is in its infancy.
Decadal variability in acoustic thermometers interpreted with ocean models
Authors: Spiesberger John , Keller Mark , Johnson Mark , Hurlburt Harley , O’Brien James
Published: October 2005

Travel times of acoustic signals were measured between the bottom-mounted Kaneohe source near Oahu and seven SOSUS stations at 3000–4000-km distance during 1983–1989. The Naval Research Laboratory hydrodynamic eddy resolving model yields changes in travel time whose standard deviations are consistent with the data. The model predicts that between 1981–1993, Rossby waves modify travel times by one second. Mesoscale eddies modify travel times little compared to Rossby waves. The largest Rossby waves are descendants of El Nino. Travel times changes are sensitive indicators of predictable features in the Naval Research Laboratory model. [Work supported by the Strategic Environmental Research and Development Program, managed by the Advanced Research Projects Agency.]
Quantitative measures of envelope cues in speech recognition
Authors: Saade Johnny , Zeng Fan-Gang , Wygonski John J. , Shannon Robert V. , Soli Sigfrid D. , Alwan Abeer
Published: October 2005

A quantitative procedure is derived to evaluate the relative contribution of envelope cues to speech recognition. Recognition data of 16 consonants in the /aCa/ form were collected using signal-correlated noise stimuli in seven normal-hearing listeners. Several distance measures were calculated directly from duration and amplitude of the acoustic envelope. One amplitude distance measure was the Euclidean distance which was computed from the squared difference of the sample-by-sample amplitudes. The second measure was the envelope difference index (EDI) [Fortune etal., Ear Hear. 15, 93–95 (1994)] which was computed from the absolute value of the difference of the sample-by-sample amplitudes. A multidimensional scaling analysis was used to convert the perceptual confusion matrix into a distance matrix and to normalize the different distance measures. Correlation coefficients were computed between the different distance measures and the perceptual data. Preliminary analysis of data from six stop consonants showed that the consonant duration alone is sufficient to explain the perceptual data (r=0.92). Although Euclidean distance conveyed less information (r=0.75) than duration, it was a better measure than the EDI (r=0.31). Evaluation of these measures on the full 16 consonant set will be discussed.