bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of the rapid speech transmission index for investigating an intelligibility problem in an Orthodox Jewish Temple
Authors: Alexander Martin
Published: October 2005

An Orthodox Jewish Temple has unique problems ensuring excellent speech intelligibility. A portion of the religious service is led by an individual who faces the front of the temple at a podium some way back from the front of the room. Religious principles forbid use of an electronic speech reinforcement system; therefore, excellent acoustics are required. An investigation of a temple having complaints of poor intelligibility was undertaken using an instrument which measures the rapid speech transmission index (RASTI). The instrument provided an objective evaluation of the existing speech intelligibility throughout the temple, and it also indicated the extent to which background noise (HVAC system) and reverberation were responsible for reduced intelligibility. To improve intelligibility, small reflecting panels were held above the various speaking positions and objectively evaluated using the instrumentation. The location and angle which provided the highest RASTI value were easily determined in real time. This proved much more effective than traditional geometric acoustics techniques.
The NIOSH criteria for the control of hand-arm vibration syndrome in occupationally exposed workers
Authors: Henschel Austin
Published: October 2005

Hand-arm vibration syndrome (HAVS) is a chronic progressive disorder with a latency period that may vary from a few months to many years. The development of HAVS in a population of workers depends on many interacting factors, including level of vibration produced by the tool, hours of tool use per day, environmental conditions, type and design of the tool, manner in which the tool is used, vibration spectrum produced by the tool, vibration tolerance of the worker, and the use of drugs and tobacco by the worker. Because of the complex interactions among these and other factors, the general lack of experimentally derived data, and the uncertainty associated with some vibration measurements, it is currently not possible to establish meaningful dose-response relationships. Thus it is not possible to establish a specific recommendation exposure limit (REL) that will protect workers against the development of HAVS in all occupational situations. Here, NIOSH has recommended a standard for exposure to hand-arm vibration that includes no specific exposure limit, but does include engineering controls, good work practices, use of protective clothing and equipment, worker training programs, administrative controls, and medical monitoring and surveillance.
Human vibration standards: Their use and misuse
Authors: Wasserman Donald E.
Published: October 2005

The architects of human vibration standards make many assumptions, which include how users of the standards will interpret and apply them. The practical use of such standards may be quite different from the framers' intent. Sometimes there is unjustified extrapolation of standardized data and guidelines beyond the prescribed scope and applications of a standard. Often, it takes a long time (even when there is adequate communication between standardization bodies and the users of standards) for standards writers to obtain the essential feedback enabling them to assimilate new and better data or collective experience in real-world applications and to revise the standards accordingly. This paper will address these and other salient issues.
Use of biodynamic models for specifying criteria and standards
Authors: Kaleps Ints , von Gierke Henning E.
Published: October 2005

Standards have been developed to characterize human whole-body response and provide tolerance criteria to vibration. The standards have been based on empirical observations of physical body responses and performance modifications. They have been further supplemented by the recognition of the dynamic responses of the body and the use of dynamic models with equivalent response characteristics. Discussed will be the basis of the current ISO standards on impedance and transmissibility, and proposed lumped parameter models that interpret the standards in terms of body segmental vibrations. For research applications, more sophisticated models have been developed that include nonlinear properties, possess algorithms for tolerance assessment, account for different spinal alignments, and can be used to assess the effects of arbitrary exposure time histories. Several dynamic modeling approaches will be reviewed that include body responses that may be related to physical impairment, ride discomfort, or injury either in a gross or anatomically localized manner. While these models were developed for solution in the time domain, it will be shown that their results reduce to those of the simple lumped parameter models under conditions of random or sinusoidal inputs and small displacements. The merits of further standardization along these lines will be discussed.
Acoustical application of fiber optic coupler sensors
Authors: Gerdt David W.
Published: October 2005

A new type of all-optical fiber strain gauge is described. Configured as a sensor, these devices are a curious mixture of interferometric and amplitude sensors, with certain benefits of both. Coupler sensors consist of fused, tapered biconical fiber optic beam splitters surrounded by a stress birefringent medium. Light is launched into one of the two input fibers and is later split among the two output fibers. At the coupling joint, the optical evanescent field is allowed to escape the normally pristine silica fiber cladding and briefly enter and be guided by another material with a large photoelastic constant. The output splitting ratio of a coupler sensor is thus made to change in response to stress applied near the coupler fusion joint. Coupler sensors may be optically sourced by semiconductor laser diodes and may be operated at remote distances without electricity. Hydrophones and microphones have been constructed on these principles that have exhibited very high sensitivity especially at low frequencies. Variations in construction methods should provide very high-frequency response as well.
Design and performance of a heterodyne all-fiber laser Doppler velocimeter
Authors: Cheyne Stanley A. , Chau Chiu , Jarzynski Jacek
Published: October 2005

A compact all-fiber heterodyne laser Doppler velocimeter (LDV) has been designed, constructed, and used to measure small in-plane displacements of a simple vibrating surface. The system is compact in the sense that no bulk optical components are used except for a small collecting lens. The laser light is coupled to a single-mode fiber using a miniature lens assembly attached to the laser. The light beam is split using a fused-fiber 3-dB directional coupler. One of the fibers from the coupler is wrapped around a cylindrical piezoelectric transducer that is driven with a sine wave near its resonance. This stretches the fiber, causing an optical phase shift which results in a modulation of the output. Then, the fibers are connected to two cylindrical rod lenses that collimate the beams. The two beams intersect at the vibrating surface of interest at oblique incidence with an angle of 20° normal to the interface. A small portion of the backscattered light is collected by a lens positioned between the two beams. This lens focuses the collected light on a photodiode. The output of the photodiode is amplified and filtered. This signal is observed on a spectrum analyzer or passed through a demodulation circuit (phase-locked loop). These two signal processing schemes and other advantages of the all-fiber LDV will be discussed. [Work supported by ONR.]
Hot topics in animal bioacoustics
Authors: Cummings William C.
Published: October 2005

A brief review of new and exciting areas of research will be given for several specialties of animal bioacoustics including passive acoustics: the use of animal sound production to assess species distribution, enumeration, and behavior; animal sonar: the abilities of marine species to modify sonar modalities in accommodation to variables in the physical environment; agroacoustics: the application of acoustical research to solve problems of biosurveys, diagnosis, and behavior associated with agricultural activities; animal hearing: new methods and findings; and high-frequency acoustics: applications to study (1) biomass patchiness, (2) climatic changes, and (3) in situ target strength measurements.
Hot topics in engineering acoustics
Authors: Finch Robert D.
Published: October 2005

Engineering acoustics might be defined as the use of the knowledge of acoustics in the design or modification of artificial systems. At the present time there are a number of areas in which it appears there is a potential for advance, as listed below. Each area is outlined in general terms and will be illustrated with one or more examples: (1) transducer design, (2) fluid dynamic sound generation and control, (3) measurement of basic acoustic quantities, (4) imaging systems, and (5) monitoring and control systems.
Hot topics in noise
Authors: Royster Larry H.
Published: October 2005

The ASA members who have indicated noise as their primary area of interest were surveyed and requested to define what they perceived to be the current “hot” topics in the noise area. Based on the responses received, the following areas (with the most frequently identified topic listed first) will be discussed during the presentation: community/environmental noise, active noise cancellation, noise control/measurement, new hearing protection technology, audiometric data base analysis, and acoustic signatures.
Hot topics in structural acoustics and vibrations
Authors: Ginsberg Jerry
Published: October 2005

Much of the current effort in structural acoustics and vibrations is devoted to improving the accuracy and efficiency with which analytical/computational methods, such as boundary elements, finite elements, variational principles, and approximate decoupling procedures, model the interaction between structural response and the acoustics field in radiation and scattering problems. A related area addresses the same questions in the high-frequency regime, where the wavelike nature of the dynamic response seems to dictate a fundamental change in the basic analytical tools. Interest in the mechanisms of energy exchange is shared by research into the response of nonhomogeneous structures (ribs and other stiffening members) in the presence of external and fluid flow. Active control of vibration and acoustic radiation and through open and/or closed loop control strategies has been of extreme interest for a long time. “Smart materials and structures” uses sensors and actuators embedded in structural components in order to actively alter the system properties. Continued progress in these areas will be expedited by continued development of near-field acoustic holography and laser Doppler velocimetry, which permit noninvasive measurement of the vibration of submerged structures. This paper will present brief summaries of the current work in each of these areas.
Hot topics in speech communication
Authors: Kuhl Patricia K.
Published: October 2005

Six hot topics will be described, two topics in each of the following three areas: speech perception, speech production, and signal processing by machines. (1) In speech perception, new studies on the representation of speech suggest that listeners' stored descriptions of phonetic units take the form of a prototype of the speech category. Adult data address the language specificity of prototypes and the effects of contextual factors on prototypes. Infant data address the developmental issue of whether phonetic prototypes are innate or whether they derive from linguistic experience. (2) Also in the area of speech perception, there are new data on the effects of talker variability. Adults, and even young infants, are capable of normalizing the speech produced by different talkers, but listeners at both ages are nonetheless adversely affected by talker variability, suggesting that attentional factors play a role in speech perception. (3) In the area of speech production, there is new emphasis on the study of articulatory timing in speech motor control. The pattern of phase relations between different articulators and its relation to linguistic structure, as well as the general coordination of speech movements, are being investigated. (4) Also in speech production, there are new advances in our understanding of laryngeal mechanisms. These advances stem from models of the glottal volume-velocity source, findings on aerodynamic phenomena at the glottis, and analyses of the mechanical properties of vocal-fold tissue. (5) In the area of signal processing, neural networks are being applied to difficult problems in speech recognition, such as the recognition of phonetic units. Computational models composed of large numbers of interconnected processing elements (nodes) have been successfully applied to the analysis of dynamic information distributed over several phonetic units. (6) Also in signal processing, the application of speech coding to hearing aids and auditory prostheses has resulted in improved speech reception. Cross-fertilization across areas in speech communication has furthered our research endeavors.
Hot topics in underwater acoustics
Authors: Kuperman W. A.
Published: October 2005

Ocean or underwater acoustics has traditionally been associated with the science and technology of sonar systems. Furthermore, sonar systems, with some exception, have traditionally been associated with the location of objects in the sea. Over the years, the science and technology of sound of the sea has developed to the state where sophisticated sonar systems exist and a growing body of knowledge has emerged with respect to the ocean environmental influence on sound. At this juncture, acoustics, oceanography, and signal processing are merging into a new medium-dominated wave physics discipline. Consequently, new directions involve exploiting oceanography for acoustics and vice versa. In the context of extracting signal from noise, the “signal” is no longer restricted to its traditional sonar-type definition, but the signal may also be the ocean/geophysics of the medium. Some of the new expected high-payoff research areas are likely to be: (1) wave physics (including scattering) of complex media, (2) ocean (including biological) monitoring/forecasting, (3) ocean imaging and new signal processing, (4) studying the air/sea interface, (5) seismoacoustics, and (6) methods of efficient sound generation.
Sounds made by a neonatal sperm whale, Physeter spp.
Authors: Ridgway S. H. , Carder D. A.
Published: October 2005

A sperm whale neonate, Physeter spp., was stranded near Sabine Pass, Texas in September 1989. The Stranding Network of Texas A&M University removed the animal to a large tank 6×12.2 m in Galveston, where it was nursed for 8 days. During this period, sounds were recorded with a broadband Racal recorder and two matched broadband B&K hydrophones placed 1 m ahead of the blowhole and 1 m lateral to the fight eye. Sounds could be divided into two classes. The click class consisted of clicks of two different types: (a) high-frequency, low-amplitude clicks with peak frequencies of 5 to 12 kHz and 1- to 2-ms duration; (b) low-frequency, high-amplitude clicks with peak frequencies of 400 to 900 Hz and durations of 7 to 20 ms. The second or grunt class consisted of different sounds, mostly below 700 Hz, described by listeners as “croaks,” “growls,” “grunts,” and “‘lion-purr growls.” Palpation of the head during phonation, listening with a stethoscope and in air at mid-head, and arrival times at the two hydrophones, suggested that click-class sounds were produced near the blowhole (distal sac and museau) while the grunt class originated 60 to 70 cm posterior to the blowhole (frontal sac).
Synthetic listeners and synthetic performers
Authors: Vercoe Barry L.
Published: October 2005

Each partner in a collaborative music performance must also be an expert listener. Several “performers” have been built for a variety of musical situations, and each given a listening skill that permits it to substitute for a human performer. This typically entails real-time pitch detection of an instrument or voice, matching the events heard against an encoded score, then adding its own part in synchronization. Necessary skills include ultra-sensitivity to changes of tempo, and the ability to improve by learning from rehersals. This has worked for a broad class of performance situations: Baroque flute/harpsichord, 20th century violin/piano, and some jazz standards—in all cases, music that can be known from a score or by acoustic repetition. Some attention has also been given to how humans first negotiate unfamiliar acoustic territory, such as perceiving rhythmic structure in a piece not heard before. A real-time auditory model of rhythmic perception and cognition (running on a desktop machine with audio I/O) suggests that the neuronal processing involved in foot-tapping to unfamiliar music may be relatively inexpensive as human tasks go.
Performance of music with an electronic violin
Authors: Négyesy János , Ray Lee
Published: October 2005

An electronic violin can produce signals suitable for controlling electronic music instruments such as synthesizers and digital sound recording and playback systems (“samplers”). In performances for audiences or for purposes of recording, the sounds made by these instruments can augment or be substituted for the sound coming from the violin itself. Consequently, it is possible to specify such novel results of performance as having sounds become quieter the more vigorously the strings are bowed, having bells or other instruments sound when the strings are bowed, or having sounds come from a variety of locations. Compositional and performance practice of music using the electronic violin recognizes that it can function as a controller as well as a soundmaking instrument in its own right. The nature of its interaction with other soundmaking resources must be specified along with the other elements of music making such as pitch and form. Several musical examples from various uses of the electronic violin will be shown from videotape and discussed.
Computer evaluation of musical performance from the acoustic signal: An exploratory study on performance anxiety
Authors: Deutsch Diana , Ray Lee , Dolson Mark , Zizook Sidney , Moore F. Richard
Published: October 2005

Performance anxiety, or stage fright, is a serious and frequently incapacitating disorder among musicians. Decrements in performance resulting from this condition include somatic disturbances such as tremor, and disturbances of perceptual and cognitive function, such as distortions of time perception and failures of attention. Two experiments on the effects of anxiolytics on accuracy and consistency of performance are here described. Professional violinists who suffered from mild performance anxiety were asked to play repeating musical passages as accurately, consistently, and steadily as possible. The performances were recorded and subjected to computer analysis. In one experiment, the consumption of a small amount of alcohol was found to be associated with a significant increment in regularity of tempo, a marginally significant increment in steadiness in playing the notes, and yet a highly significant decrement in consistency of intonation. A second experiment which examined the effects of two prescription anxiolytics is also described.
Relationship between hearing loss and noise exposure levels in a large industrial population: A review of an overlooked study
Authors: Alton Burks J. , Burgi Ernest J.
Published: October 2005

Approximately 25 years ago researchers at the University of Pittsburgh conducted a comprehensive study for the U.S. Public Health Service to examine the relationship between hearing loss and exposure to steady-state industrial noise. Results of the study were presented by E. J. Burgi and K. C. Stewart at the 33rd Annual Meeting of the Industrial Hygiene Foundation, Pittsburgh, PA, 16 Oct. 1968. However, for reasons unknown, the study has been overlooked by researchers and technical search services. The research was accomplished with the cooperation of a large midwestern manufacturer. The noise exposure of this company's heavy industrial workers could be well documented over a period of many years since the noise environment had not changed significantly. A total of 2983 subjects were given pure-tone air conduction threshold tests. The study was initiated in 1958 with final data collection completed in 1965. This paper will provide a summary of the findings of the study.
Predicting sound levels from wind speed in a coniferous forest
Authors: Sneddon Matthew , Fidell Sandy , Silvati Laura , Pearsons Karl , Harrison Robin
Published: October 2005

Sounds created by the interaction of wind and foliage (as well as sounds of running water and animal populations) are the principal sources of the ambient noise environments in many uninhabited areas. Since these indigenous sources create much of the masking energy in outdoor recreational settings, which limits the audibility of noise intrusions, characterizing their influence is an important step in predicting and managing natural quiet. Cross-correlational analyses of time series of wind speed and A-weighted sound-pressure observations in a wilderness environment indicate that over half of the variance in ambient sound levels can be predicted from knowledge of wind speed. [Research sponsored under National Park Service Contract CX-2000-9-0026.]
The propagation of higher-order mode, high-intensity sound in ducts: The case of imperfect resonance
Authors: Anderson M. J. , Vaidya P. G.
Published: October 2005

The analysis of the propagation of higher-order modes of sound at high intensities is relatively easy in the absence of resonance. However, it is known that in rectangular ducts, higher-order mode., form resonant wave packets, such that two modes at different modal orders and frequencies can have an identical phase speed. A resonance expansion method has been used in the past to calculate the modal amplifier. This paper deals with a third case: that of imperfect resonance. This case is routinely encountered, for example, in the analysis of the propagation in hollow circular ducts. A solution technique is presented that uses a detuning parameter and the method of characteristics. The solution shows a beat phenomenon, and the resonance effects get progressively weaker as the detuning parameter gets larger. The method thus unifies the three cases.
Observations of standing solitons in a parametrically driven pendulum lattice
Authors: McClelland Charles , Denardo Bruce , Larraza Andrés , Greenfield Alan , Putterman Seth
Published: October 2005

Using a simple string-and-mass design, an experimental one-dimensional lattice of coupled pendulums has been constructed. Steady-state motion is obtained with a global parametric drive. Standing solitons of both the breather and kink type have been observed in the lower and upper cutoff modes, respectively. As the drive parameters (frequency and amplitude) are slowly varied, there can occur instabilities in which the character of the breather dramatically changes. In one region of the drive plane, the breather undergoes quasiperiodic motion in which the amplitude and width oscillate. In another region, the quasiperiodicity is absent and the energy is confined to nearly a single lattice site. The kinks have the remarkable feature that they can exist in modes other than the upper cutoff mode, and even between domains of different modes. These kinks differ from the upper cutoff type in that their structure depends upon the nature of the mismatch of the two domains.
Numerical studies of standing solitons in a nonlinear lattice
Authors: Galvin Brian , Denardo Bruce , Larraza Andrés
Published: October 2005

A numerical model of a one-dimensional lattice of linearly coupled nonlinear oscillators was developed using a simple Euler's method algorithm. The model includes linear dissipation and global parametric drive. Standing breather and kink solitons were observed in the lower and upper cutoff modes, with parameters that agree closely with the nonlinear Schrödinger (NLS) theory. The solitons were found to be stable even when the assumptions that lead to the NLS solutions are violated, indicating the robustness of these structures. Also observed were stable kinks in modes other than the upper and lower cutoff modes, and stable transition regions between domains of different modes. There currently exists no theoretical description of these latter structures. All of the numerical results are in qualitative agreement with results previously obtained with an experimental pendulum lattice.
Nonlinear evolution equations for fields with a level repulsion spectrum
Authors: Larraza Andrés , Denardo Bruce
Published: October 2005

The description of the vibrations associated with polar modes in a crystal, or gravity waves on the surface of a stormy sea, must take into account the linear coupling of the polar mode to the electric field in the former, or the coupling of the surface wave to the theoretically predicted second sound [Larraza et al., Phys. Rev. A 41, 3144–3155 (1990)] in the latter. These two systems lead to the appearance of level repulsion in their excitation spectrum and to a minimum in the group velocity. At this minimum, a balance between the nonlinearity and the dispersion effects cannot be achieved in the standard nonlinear evolution equations for the modulation of a given field. Higher-order dispersive effects must then be incorporated for the consideration of waves of permanent form.
Nonlinear scattering of crossed focused sound beams in the presence of turbulences—Theoretical results
Authors: Korman Murray S.
Published: October 2005

A theoretical study involving the interaction of mutually perpendicular crossed continuous wave ultrasonic beams overlapping (at a common focal point) and interacting in the presence of turbulence in water leads to a prediction of the far-field radiated sum frequency pressure. Earlier experimental results [M. S. Korman and S. C. Rife, “Nonlinear Sound Scattering of Crossed Focused Beams in the Presence of Turbulence,” Proc. 13th Int. Cong. Acoust., Belgrade, Yugoslavia (1989)] measured the profile of the radiated sum frequency pressure by scanning the overlap region across the width of turbulence produced by a submerged circular water jet (Re = 8.5 × 104). In scanning, the receiver transducer unit moves fixed relative to the senders (of primary frequencies f1 = 2.05 MHz and f2 = 1.95 MHz). Pressure scans compare well with known values of the radial turbulent rms velocity profile ur (r). These results can be explained in part by modifying an existing theory [M. S. Korman and R. T. Beyer, J. Acoust. Soc. Am. 85, 611–620 (1989)] to include the effects of amplitude and phase fluctuations by turbulence on the primary beams, focusing and allowing for anisotropic turbulence. [Work supported by the Naval Academy Research Council.]
Application of the method of matched asymptotic expansions to vibration problems of thin cylindrical shells
Authors: Wong Seung Kai , Bush William B.
Published: October 2005

The use of membrane approximation simplifies considerably the analysis of thin shell vibrations. The approximation breaks down at locations of physical discontinuities such as boundaries, joints, attachments, etc. The method of matched asymptotic expansions can be used to treat the effect of bending in a narrow region near the discontinuity. It results in boundary or joint conditions to be applied to the membrane equations of motion that hold in the main part of the shell. Examples will be considered from the low-frequency vibrations of cylindrical shells with clamped ends, with hemispherical caps, with ring stiffeners, and with partitions.
Transient radiation and scattering from fluid loaded elastic cylinders
Authors: Stepanishen Peter R. , Janus Robert S.
Published: October 2005

Two-dimensional radiation and scattering from fluid-loaded circular elastic cylinders are addressed using two different time domain techniques. In the first method, the normal velocity of the shell is expanded as a Fourier series of angle with time-dependent coefficients whereas, in the second method, the velocity field of the shell is expressed as an in vacuo modal vector expansion with time-dependent coefficients. In both methods, the velocity coefficients are expressed as the solution of convolution integral equations and the field pressures are then expressed as a Fourier series in angle with range- and time-dependent coefficients that are convolution integrals involving the velocity coefficients. Recursive and iterative methods of solving the convolution integral equations are presented and discussed. Finally, numerical results are presented and discussed for the normal velocity and surface pressure resulting from a transient line force excitation and an incident transient plane-wave excitation.
Properties of porous PZT ceramics and their application to hydrophone
Authors: Ayusawa Kazutoshi , Arai Toru , Sato Housaku , Kawamura Kazutami , Miyata Tetsuji , Kobayashi Keiichi
Published: October 2005

The relationship between porosity and piezoelectric and mechanical properties of porous PZT ceramics and hydrophone sensitivity was investigated. Furthermore, hydrophone sensitivity in high hydrostatic pressure (10∼80 kg/cm2) was measured. As a consequence of this investigation, it has been found that porous PZT ceramics are an excellent material for hydrophones. Relative permittivity and flexural strength decreased proportionately with increase in porosity. The piezoelectric voltage coefficient (gh) and hydrophone sensitivity increased with an increase in porosity. At the porosity 50%, relative permittivity became approximately one-third, flexural strength became one-fifth, gh increased by one order more, and hydrophone sensitivity was improved more than 20 dB when compared to the value at the porosity 0%. Hydrophone sensitivity decreased only 1.5–2.0 dB with the increase in hydrostatic pressure from 10 to 80 kg/cm2. Porous PZT ceramics were produced with the following process. The PZT slurry having dispersed spherical carbon particles was made into green sheets. The green sheets were made into laminated moldings. The moldings were heated slowly to burn out the binder and carbon particles at firing. Then carbon particles changed pores.
A piezoelectric copolymer hydrophone array and piezoelectric copolymer and polymer hydrophones
Authors: Schrodt Joseph K.
Published: October 2005

A previous laboratory study [J. K. Schrodt, J. Acoust. Soc. Am. Suppl. 1 87, S128 (1990)] confirmed the broad bandwidth nature and high receive response of a piezoelectric copolymer material (PVF2/PVF3). The results of the previous study provided a technical framework for the future use of this material in hydrophone design and construction. The present talk is concerned with the performance of a broad bandwidth copolymer hydrophone array whose specifications were based on this technical framework. A comparison is also made between an air-backed cylindrical hydrophone with piezoelectric copolymer material bonded to the inside wall of the cylinder and the same hydrophone except with polymer (PVdF) material as the piezoelectric element. The effect of copolymer/polymer thickness and the use of different window materials for the cylinder wall are investigated. It is expected that the thicker copolymer material will increase the hydrophone sensitivity and also extend its usable frequency range relative to the PVdF material which is less reactive.
Vocalic duration as a cue to consonant voicing
Authors: Crowther Court , Mann Virginia
Published: October 2005

It has been proposed that preceding vocalic duration is a universal cue to final consonant voicing in CVC monosyllables [M. Chen, Phonetica 22, 129–159 (1970)]. To test this hypothesis, three experiments compared native speakers of English, Mandarin Chinese, and Japanese. Experiment 1 measured the duration of the vocalic portions in the subjects' productions of “pod” and “pot.” Experiment 2 assessed subjects' identification of natural tokens of “pod” and “pot” with and without bursts. Experiment 3 assessed their categorization of synthetic /pod/-/pot/ stimuli that differed in vocalic duration and F1 offset frequency. In each of these experiments, the native speakers of English showed the strongest implementation of and sensitivity to vocalic duration as a cue to consonant voicing. The Mandarin Chinese speakers showed significantly weaker effects, and the Japanese fell in between. These findings qualify theories about vocalic duration contrast as a universal cue: While there may be a universal tendency to lengthen the vocalic portion before voiced stops, the magnitude of the contrast seems to be determined by language specific considerations.
Approximations for rough surface scattering: Beyond plane waves
Authors: Bennan David H.
Published: October 2005

Most theoretical work on rough surface scattering concerns monochromatic plane waves incident on infinite irregular interfaces in a constant sound-speed environment. Experiments, on the other hand, most often use pulsed point sources or beams in a ducted environment. Here, various approximations used for plane-wave scattering are extended to point sources in the time domain. The Kirchhoff and small-slope approximations prove to have simple forms for both the near and far field. Dashen's formula for plane waves can be generalized to a limited extent for point sources in the time domain in variable environments. Since, for plane-wave scattering from sinusoidal surfaces, the Schwinger variational principle gives scattering amplitudes whose phases are closer to exact phases than any of the standard approximations, the Kohn and Schwinger variational principles will be examined as starting points for approximations of reverberation in ducted environments. [Work supported by NRL.]
Design of an experiment to measure low-frequency acoustic monostatic backscatter in the open ocean
Authors: DeFerrari H. A. , Nguyen H. , Willemsen J.
Published: October 2005

An experiment has been designed to measure acoustic backscatter from the ocean wave surface simultaneously with surface wave measurements of the SWADE experiment. The objective is to measure scattering cross section Doppler broadening for grazing angles of 15 to 2 deg, at frequencies of 100, 200, 400, and 800 Hz for the purpose of comparison with perturbation theory. Constraints are that the system be operated under battery power at sea, unattended for a period of 2 months or more, with measurements at 1-h intervals. Design parameters of the source and receiver array are driven by signal-to-noise considerations, whereas the signaling format is driven by predicted Doppler broadening and data storage. Depth of the source and receiver is optimized to give time-gated arrivals for low grazing angle before the fathometer return and long enough in transmissions in time to resolve Doppler broadening. Ambiguity functions for cw pulses, pseudorandom codes, and FM sweeps are considered and compared. A solution appears possible, but just within the constraints of experimental geometry and power and storage capabilities.
Numerical studies of rough surface scattering models
Authors: Broschat Shira Lynn , Thorsos Eric I.
Published: October 2005

In recent years a number of rough surface scattering models have been introduced that attempt to “bridge the gap” between the classical perturbation and Kirchhoff approximations. Among these are the phase perturbation technique and the small slope approximation. Investigations have shown that for pressure-release surfaces with a Gaussian roughness spectrum, the phase perturbation model is accurate in cases when the classical approximations fail. Monte Carlo calculations by Betman for the second-order small slope approximation show excellent agreement with results obtained using the Rayleigh-Fourier method both for wind-driven sea surfaces and for the fluid-solid boundary condition. In this work, the first- and second-order small slope approximation reflection coefficients and bistatic scattering cross sections are derived for the Dirichlet (pressure-release) problem. The first-order results are shown to reduce to those of the perturbation and Kirchhoff methods for the reflection coefficient and to that of the perturbation method for the bistatic scattering cross section. In addition, phase perturbation results are calculated for a multiscale (Pierson-Moskowitz) surface spectrum. For both models, numerical results for one-dimensional, pressure-release surfaces with a Pierson-Moskowitz spectrum are compared with exact numerical results obtained using a Monte Carlo technique.
Near-field acoustic scattering from rough surfaces
Authors: Caruthers Jerald W. , Keiffer Richard S.
Published: October 2005

Criteria for the Fraunhofer approximation for scattering from a rough surface are reviewed and restated in a new convenient form. Like the early work of Melton and Horton [D. R. Melton and C. W. Horton, J. Acoust. Soc. Am. 47, 290–298 (1970)], it shows the importance of recognizing that the scattering patch size increases with distance from a source of constant beamwidth. The importance of the common assumption of an incident plane wave is discussed. Very little practical sonar work satisfies the standard Fraunhofer criterion for the far field. Coherent and incoherent scattering is discussed and model simulation results for the Kirchhoff approximation are presented. Results are consistent with both those of Horton and Melton [C. W. Horton and D. R. Melton, J. Acoust. Soc. Am. 47, 299–303 (1970)] that show a strict application of the standard Fraunhofer criterion for the far/near field transition distance for scattering coefficient and those of Lysanov [Yu. P. Lysanov, Sov. Phys. 17, 74–76 (1971)] that show a relaxation of the criterion for incoherent scattered intensity. The two are reconciled by the normalization applied to the scattered intensity to obtain the scattering coefficient. Significant differences do, however, remain for both the coherent and incoherent intensities. [Work supported by ONR, part of which is through the Acoustics Reverberation Special Research Program.]
A new model for marching computation of ocean acoustic backscattering
Authors: Lee D. , Mary D. F. St. , Schultz Martin , Siegmann W. L.
Published: October 2005

In the prediction of long-range ocean acoustic propagation, one important physical phenomenon that often cannot be ignored is the occurrence of backscattering. When backscattering is present, it is either strong or weak. In the latter case, it can be either negligible or non-negligible. Except in the “negligible weak” case, the influence of the backscattering must be considered. In this paper, a new, stable numerical technique for handling non-negligible weak backscattering is introduced. The discussion of a representative backscattering equation begins with a strong outgoing component. Then the portion of weak backscattering is mathematically identified. A marching numerical technique is described for the solution of this elliptic partial differential equation that incorporates in a natural manner the weak backscattering. Stability of the numerical scheme is an important consideration. In addition, whenever the environment changes such that the medium becomes range independent, a boundarylike condition is imposed in the process so that only outgoing waves are assured. Extending this approach to handle strong backscattering encountered from well boundaries and/or obstacles will also be briefly discussed. [Work supported jointly by ONR and NUSC.]
Modeling and optimization of a cardioid hydrophone
Authors: Granger C. , Lavie A. , Decarpigny J. N.
Published: October 2005

A hydrophone with an intrinsic cardioid directivity can be designed using a bilaminar or trilaminar piezoelectric element submitted to the direct acoustic pressure on one of its faces and to the same pressure properly lagged on the other face. Such a condition can be realized by mounting this element as the bottom of an oil cavity, the top of which includes a very thin slit that ensures pressure transfer between the surrounding water and the internal oil. Then, using standard equivalent electrical components, the cavity acts as a capacitor, while the slit is simultaneously an inductor (mass effect) and a resistor (oil viscosity effect). Thus, a proper choice of geometrical and physical parameters can provide the required phase lag in a more or less important bandwidth [A. Defebvre, J. Pouliquen, and J. P. Deparis, Proc. Ultrasonics International, 408–413 (1983)]. The design of such a hydrophone requires the correct selection of parameters as well as the solutions of technological problems. This communication will discuss the first point and describe the modeling effort that has been made to set up an optimization procedure. The modeling process can be split into five steps: (i) a finite element modeling of the active part, providing its equivalent circuit in the frequency range of interest, (ii) an integral equation modeling of the hydrophone external surface, providing the diffraction constants and the radiation impedance, (iii) an analytical modeling of the oil cavity and the slit, providing also their equivalent circuits, (iv) the assembling of the different components in a global equivalent circuit, (v) the computation of the hydrophone sensitivity and the optimization loops. Though simple, the global circuit used here allows an accurate prediction with respect to measurements and is an efficient design tool. [Work supported by G.E.R.D.S.M., D.C.A.N. Toulon.]
Simulating annular array probe performance by ray tracing
Authors: Guess Joe F.
Published: October 2005

The imaging performance of annular array probes has been simulated by a ray tracing method. A particular strength of the method is the ability to account for refraction and attenuation of materials between the transducer and the imaging point, including coupling fluid, probe cap, and tissue layers. Rays are traced from the surface of the transducer to the field point under consideration. The aperture function, real and imaginary parts, is reconstructed as seen from that point. Beam profiles are determined by a Fourier transform of the aperture function. Electronic functions, such as time delay focusing, apodization, errors in gain, and time delay, can be simulated by modifying the aperture function appropriately. Examples are given of nonspherical geometry and effects of subcutaneous fat layer. Apodization is shown to require extremely tight phase control, both across transducer elements and in focusing accuracy.
The pressure distribution in the cell structure (standing waves) of under-expanded supersonic jets
Authors: Powell Alan
Published: October 2005

Rayleigh's principle, based on a circular jet, yields the cell length (defined by the first mode) of a square jet only 4% too long [J. Acoust. Soc. Am. Suppl. 1 87, S80 (1990)]. Yet the cell structure is fundamentally different. The square one is dominated by expansive plane waves moving in (at propagation velocity c) from each side (length l) reflecting repeatedly from the opposite sides, with axial period corresponding to 2l/c, accompanied by expanding compressive waves centered on each corner that bring the plane waves to ambient pressure at the edges. The axial pressure distribution is quite nonperiodic: The periodic cell length, corresponding to (1/√)×2l/c, is not very overt. In the circular case the converging cylindrical wave “reflects” from the center with a rather impulsive compressive wavefront, resulting in almost ambient pressure across the jet at time D/c; the original overpressure is almost exactly reversed at time 2D/c. The periodic cell length, however, corresponds to (π/2j0.1) × (2D/c) = 0.6531 × 2D/c. [Work partially supported by the Texas Advanced Research Program.]
Noise radiation from a subsonic jet using correlations between hot-wire probes and Sfar-field microphones
Authors: Shen Jianping , Meecham William C.
Published: October 2005

This is a supplementary study to the previous research on noise from a jet, using correlations between pressure transducers and far-field microphones. A 1-in.-diam cold jet with variable jet speeds (up to Mach number 0.8) was used in this experiment in the UCLA Aerosonics Laboratory anechoic room. Cross correlations between a DISA hot-wire and a B-K microphone placed at different locations around the jet nozzle were measured and analyzed, for a free or surface impinging jet. The directivity patterns confirmed the quadrupole nature of the jet-to-plate noise that was found earlier. The data of free-jet noise indicated the agreement with the prediction of Martin Goldstein, “Aeroacoustics,” NASA Report N74-35118 (1974) but only for lower Mach numbers. There was significant disagreement for Mach numbers >0.4. The question will be discussed.
Pitch salience and generative harmonic resolution of major triad inversions
Authors: Perry David W. , Marin Oscar S. M.
Published: October 2005

Subjects from a broad range of musical experience were presented with inversions of the major triad, and asked to sing the most salient pitch, and the pitch that would best follow the chord. Responses were recorded by computer via voltage-to-music instrument digital interface conversion. Responses for salience did not differ significantly with musical experience, and correspond with predictions based on subharmonic matching [Tehrhardt, Tiefenstrukt ur der Musik (1982); Parncutt, Music Percept. 6, 65–94 (1988)], and with the results of other empirical measurements. Results for choice of resolution do not confirm the specific predictions of music theory, specifically the cadential resolution of the second inversion, except for musicians with highly developed skills in formal musical analysis. Responses do however show a significant increase in resolution to the tonic, to the dominant, and to the diatonic set, with experience. These results demonstrate the difference between psychoacoustic and cognitive levels of music perception, with the former less influenced by experiential variables, and the latter indicating a continual strengthening of the basic internalized schemata that underlie culturally based tonal systems throughout musical development.
New estimates of sound speed in water at high pressure
Authors: Spiesberger John L. , Metzger Kurt
Published: October 2005

Measured travel times of acoustic pulses, propagated across a 3000-km section of the north Pacific Ocean, are inconsistent with travel times predicted with the internationally accepted algorithm for the speed of sound in water. The sound-speed algorithm predicts a speed that is too fast at oceanic pressures found below about 1-km depth. An accurate algorithm of sound speed is important for deriving large-scale temperatures from measurements of acoustic travel time across oceans. Accurate estimates of the large-scale thermal field are important for better understanding the ocean's role in determining weather, climate, and the distributions of marine organisms.
Modeling the propagation of a pulsed acoustic signal on the Connection Machine
Authors: Palmer David R. , Paisley James A.
Published: October 2005

Ocean acoustic remote sensing requires that one be able to obtain a quality solution to the forward propagation problem. While several excellent sound propagation models exist, their application to global- and even basin-scale problems can require an inordinate amount of processing time on a conventional supercomputer. One solution to this problem is to develop propagation models that run on massively parallel computers such as the Connection Machine (CM). This work describes solving the 2-D parabolic equation for a pulsed acoustic source on the CM at the Naval Research Laboratory. A computer program has been developed that will solve the parabolic equation for a source describable by up to 1024 frequencies, at computational speeds greater than 1-ms/range-step/Fourier component, and is able to store and manipulate data such that contour plots can be constructed for each time step of the pressure field in the range-depth plane. Processing times will be significantly improved when the next generation CM becomes available.