bluuebunny/crossref_metadata_2025 huggingface dataset:
Airport noise monitoring for Boston area airports
Authors: Timmerman Nancy S.
Published: October 2005

Airport noise has been monitored at Logan International Airport since 1975. Recently, Massport decided to install a new noise monitoring system. The new system will monitor trends in noise impact by time of day, season, and on an annual basis; measure noise levels generated by aircraft taxiing, ground operations, reverse thrust, takeoffs, landings, and overflights; obtain accurate data on aircraft flight tracks and fleet mix to be used in the generation of noise contours; and assess the performance of the Logan Preferential Runway Advisory System in terms of runway utilization and noise exposure. To do this, noise data from some sites will be obtained in 1/3-octave bands as well as in the traditional A-weighting; C-weighting is available; radar tracking information is expected to be part of the system; and weather data will be obtained at about half of the sites. All data are saved in database for study of the correlation of noise with various factors. A complaint database, contour prediction mode (FAA integrated noise model), and mapping software are also part of the system. It is expected that this system will be used to evaluate different noise descriptors against actual complaints, and to suggest improvements to noise prediction models based on geography or meteorological effects.
Airport noise and passive radar monitoring for Oakland International Airport
Authors: Woodman Glenn
Published: October 2005

Airport noise has been monitored at Oakland International Airport since early 1970s using mobile noise-monitoring terminals for one week sampling each calendar quarter in order to meet requirements of California state noise regulations. The Port of Oakland has recently installed a permanent airport noise and operations monitoring system that will enable achievement of three primary objectives: (1) gather acoustical data to meet California airport noise standards, (2) remove contribution of overflights from San Francisco International Airport to Oakland's noise exposure map, and (3) develop aircraft flight track measurements and positive identification of aircraft operators for community noise complaint resolution. Noise monitoring systems typically are passive in measuring only noise events. Oakland's system incorporates flight operations data and passive airport surveillance radar data to provide a proactive management tool for monitoring effectiveness of and compliance with existing noise abatement procedures. A discussion of this system will be made regarding its effectiveness in monitoring compliance with noise control procedures and in resolving community noise complaints.
Intelligent aircraft noise monitoring terminals
Authors: Wallis Alan D. , Krug Robert
Published: October 2005

Current technology airport monitoring units using, “short Leq” as the data transfer units, allow much more and better data than has been previously possible. With very large internal stores, in the order of 2 megabytes, the new generation of units can simultaneously store raw data elements and full environmental information as well as each aircraft event. The pattern recognition built into the units will allow each noise monitoring terminal on the system to recognize aircraft flying over. Then, by a template comparison technique, it both stores the resultant data and transfers it to a remote hoist for correlation. The terminal incorporates some learning capability to increase the “hit rate” of recognition. Any, or all, of the acquisition parameters in each terminal can be configured from the host using a modem link. In a similar way, diagnostics can be performed from the host without visiting each terminal. Typically, 1 to 2 weeks of raw data and up to 10 000 aircraft events are stored in each terminal. This allows for unattended operations as well as security backup for the host.
A new cochlear model: Viscous fluid motion
Authors: Wan Wanggen , Fan Changxin
Published: October 2005

The cochlear fluid is considered to be actual viscous fluid in this paper and the Navier-Stokes equation used to describe the viscous fluid motion is linearized and then transformed to a typical transport equation and a Poisson equation. By solving the two equations using the Fourier series method, a new two-dimensional cochlear model is finally derived. The frequency responses of the model are presented and believed to be much more improved than those derived before, especially in the low-frequency slope. Therefore, they are more consistent with recent experimental data [Robles et al., J. Acoust. Soc. Am. 80, 1364 (1986)]. It appears that the inclusion of the fluid viscosity sharpens the low-frequency slope of the cochlear model. The high-frequency slope is not as sharp as desired for the effects of the middle ear and the basilar membrane (BM) nonlinearity (signal-dependent damping) are not included. The new cochlear model also makes such inclusion feasible.
Are high-frequency fibers necessary for speech perception in noise
Authors: Strickland E. A. , Viemeister N. F. , van Tasell D. J.
Published: October 2005

It has been proposed that auditory-nerve fibers whose CFs lie above the frequency region of speech may encode the periodicity of low-frequency signals, and may be used to perceive speech when the signal-to-noise ratio is low [S. Greenberg and W. Rhode, J. Acoust. Soc. Am. Suppl. 1 88, S23 (1990)]. If this is true, then it might be expected that identification of speech at low signal-to-noise ratios would worsen with the addition of a high-pass noise that is sufficiently intense to mask information in the high-frequency fibers. This hypothesis was tested for identification of vowels and spondees. Identification was measured as a function of signal-to-noise ratio in speech-shaped noise, with and without high-pass noise. The high-pass noise had a low-frequency cutoff of 3 kHz. The results indicate that the addition of high-pass noise does not degrade identification performance, regardless of the level of the speech-shaped noise, and also does not change the confusions made by listeners. These results suggest that the high-frequency channels are not necessary for speech perception under low signal-to-noise conditions or in quiet. [Supported by DC00110.]
Coupling of plate and shell modes at joints
Authors: Lu I-Tai , Bertoni Henry L. , Chen H. Y.
Published: October 2005

For cylindrical and spherical shells without truncation or for flat plates with infinite lateral extent, fundamental shell or plate modes propagate independently without coupling. However, at a joint of two or more plate or shell elements, these modes couple together. If a mode is incident at an oblique angle from one element, it will excite other modes propagating away from the junction in each element. The propagation direction and the excitation strength of each mode can be determined by the following boundary conditions: continuity of displacement at the joint, continuity of rotation about the axis of the joint, and vanishing net force and torque on the joint. These boundary conditions are derived from the assumption that the joint is massless and has rigid cross section but offers no resistance to extension along and twisting about the axis of the joint, and to bending transverse to the axis. To be consistent with thin plate/shell theory, it is necessary to account for the first cutoff mode in addition to the three propagating modes in each plate or shell. Numerical examples will be discussed. [Work supported by ONR.]
Natural frequencies and bending mode shapes of thin perforated plates using a variational method
Authors: Beslin Olivier , Millot Pascal , Guyader Jean-Louis
Published: October 2005

A theoretical method to predict eigenfrequencies and mode shapes of a perforated plate was developed by building its Hamiltonian as a functional of the displacement field. The displacement functional base was chosen to be the natural base of a nonperforated plate having the same geometrical and mechanical characteristics as the perforated one with simply supported boundary conditions. Limiting the base vectors to a finite number, the extremization of the Hamiltonian was transformed into a Rayleigh-Ritz problem. Formulas of this analytical development were implemented on a computer to solve the eigenvalue problem for any kind of rectangular perforations. Numerical singularities were encountered, regarding the holes' shapes and sizes, and vector sets. They were removed by using some simple physical considerations. The program developed for this study was tested by treating special cases, well known in the literature. For example, the case of a full plate with free boundary conditions was simulated by introducing a crown of holes around the edges of the plate, setting it free of its supports. Several cases of perforated plates were also computed. This work is the first part of a more general study on sound radiation from plates with holes and perforations.
The degrees of freedom in controlling articulations
Authors: Johnson Keith , Ladefoged Peter , Lindau Mona
Published: October 2005

What do speakers control in the production of vowels? Data from two groups of five speakers saying words containing ten different American English vowels indicate that in saying the same vowel there is a great deal of variation between speakers in the articulatory gestures used, but considerable consistency within speakers in the articulations used. All ten speakers had constrictions in similar regions of the vocal tract for each vowel; but the relation between tongue movement and jaw movement was variable. Principal components analyses of the locations of six pellets showed that, for one group, two of the five subjects used the jaw and tongue in combination, and their vocal tract shapes could be described in terms of only two components. For the other three subjects, three components were needed to account for the same amount of variance, with the third component distinguishing tense and lax vowels. The other group of five subjects was analyzed separately. Two subjects showed good correlation between tongue height and jaw height; for the other three, tongue height was not well predicted from jaw height, except in the case of back vowels. These speakers used various combinations of articulatory mechanisms for separating tense and lax vowels. Lip positions were also examined. Even in the case of back vowels, only some of the speakers had good correlation between lip opening and protrusion. In conclusion, the evidence that vowel production is goal oriented is discussed using targets learned as auditory goals but produced as individually controlled articulatory gestures. [Work supported by NIH.]
An overview of the tomographic forwnrd/inverse problem
Authors: Cornuelle Bruce D. , Howe Bruce M.
Published: October 2005

In ocean acoustic tomography, the travel time along a ray path is a weighted average of the propagation speed along the path. Because oceanographers generally have intuition about point measurements or simple averages, it has been necessary to transform travel time data into point values (maps) before communicating the results. The transformation can be done with a variety of methods, ranging from exhaustive Monte Carlo searches to Backus-Gilbert constrained estimation. The transformation converts travel time data with more or less independent errors to point value estimates with correlated errors that may have complicated, nonlocal structure. Since the error bars usually presented with an ocean map do not include the correlations, they do not accurately reflect the information content of a tomographic dataset. In addition, it is no longer possible to distinguish between the data errors and sampling blind spots by examining the error bars (or even the error covariances). Communicating tomographic results thus requires more effort, and more plots. Resolution (or averaging) kernels show how the estimate at a point is a weighted average of the entire field (with the average becoming more local as the number of rays increases). Null space vectors show fields that may be added to the estimated map without changing the data significantly. Given that the goal of ocean observations is to test dynamical hypotheses, it is also reasonable to consider transforming hypotheses into constraints on the travel times, rather than transforming the travel times into constraints on physical space hypotheses. [Work supported by ONR and ONT.]
Converting bottom loss measured from a rough layered sediment to the equivalent “flat bottom” loss
Authors: McCammon Diana F.
Published: October 2005

In the BLUG parameter-estimation technique, measured bottom loss is inverted to obtain a “best-fit” set of ten geoacoustic parameters that characterize the sediment. This inversion process has been improved and automated with Monte Carlo methods; however, in spite of these advances, the inversion process can still give poor results, notably in rough thin sediment regions, because the inversion model assumes flat interfaces between water, sediment, and basement. The purpose of this paper is to describe a correction factor that can be applied to the measured data to convert it from rough surface loss to the equivalent loss if the interfaces had been smooth. With this correction, the data can be made to conform to the assumptions of the model, which should lead the inversion process to a better fitting set of parameters. Four examples of this application are shown; in two thin sediment cases, the correction gave improved model/data correlations and lower squared errors; in the two smoother thicker sediment cases, the correction did not significantly affect the result. [Work supported by NAVOCEANO.]
Matched-field processing (MFP) tomography for inverting the El Niño profile
Authors: Shang E. C. , Wang Y. Y.
Published: October 2005

The matched-field processing (MFP) method has been substantially applied for source localization studies in recent years. It has been demonstrated that the MFP is very sensitive to the mismatch of sound-speed profile (SSP) with a high-resolution MFP estimator. It turns out that the high-resolution MFP is also a potential powerful tool for SSP inverting with a known source-receiver system [A. Tolstoy and O. Diachok, J. Acoust. Soc. Am. Suppl. 1 88, S117 (1990)]. In this paper, the high-resolution mode matching (HRMM) estimator [E. C. Shang, J. Acoust. Soc. Am. 86, 1960 (1989)] has been used for El Niño profile inverting. By matching a proper set of modal travel time perturbation, the El Niño profile can be efficiently inverted in a 2-D parameter space based on a simple acoustic model of the 1982-1983 El Niño event. [Work supported by ONR and NOAA.]
Tomographic reconstruction of stratified fluid flow
Authors: Rouseff Daniel , Winters Kraig B. , Kaczkowski Peter
Published: October 2005

A new method for imaging a moving fluid using acoustic tomography is evaluated by numerical simulation. A cross section of the medium is probed by high-frequency acoustic waves from several different directions. It can be shown that the resulting measured travel time data contain sufficient information to reconstruct both the spatially varying sound speed and the transverse component of the fluid vorticity [K. B. Winters and D. Rouseff, Inverse Problems 6, L33 (1990)]. The results are exact to within the validity of the straight-ray geometric acoustics approximation. To evaluate a discrete version of the reconstruction algorithm, a three-dimensional stably stratified mixing layer is simulated. The flow exhibits characteristic features in both density (sound speed) and vorticity. The dynamics of the fluid flow can be described as the instability of a vortex sheet. The acoustic travel time is calculated by integrating through the simulated flow fields. The synthetic data are then inverted to yield reconstructions of both the density and the vorticity of the evolving flow. [Work supported in part by the U.S. Navy under Contract No. N00039-89-C-0001.]
Experience with early/reverberant sound energy ratios as a measure of auditorium acoustics
Authors: Marshall L. Gerald
Published: October 2005

The advent of portable computerized instrumentation has made it practical for the acoustical consultant to collect extensive time/energy/frequency data during routine auditorium checkouts and to easily derive a number of potentially useful room acoustics measures from these data. The early/reverberant ratio is one measure that appears to correlate fairly dependably with the characteristics of clarity and reverberance for both speech and music. Experience with early/reverberant ratios will be discussed and measured data will be examined with respect to the variables of reverberation time, frequency, source and receiver locations, boundary reflectivity, and energy-ratio integration times.
Study of bowed string motions with optical detectors
Authors: Hanson Roger J. , Dirkes Lawrence L. , Schneider Andrew J.
Published: October 2005

Bowed string phenomena have been studied on a system in which both ends of a string are mounted rigidly to a steel beam. Waveforms are studied at the “nut” and the “bridge” ends with photon-coupled interruptor modules (PCIM) [R. J. Hanson, Phys. Teacher 25, 165–166 (1987)]. At positions farther from the ends, where the amplitude of string motion is greater than the linear region of the PCIM, one-dimensional photodiode arrays are used in an arrangement modified from that reported earlier [T. Nakamura, L. L. Dirkes, and R. J. Hanson, J. Acoust. Soc. Am. Suppl. 1 86, S16 (1989)]. Emphasis is on the study of string motions with periods much greater than any natural period of the string which can be obtained with bowing forces greater than the Schelling maximum [R. J. Hanson, A. J. Schneider, and F. W. Halgedahl, J. Acoust. Soc. Am. Suppl. 1 86, S15-S16 (1989)]. The waveforms observed at different positions have been used to investigate the triggering of this motion with a period longer than that of the normal slip-stick bow and string interaction triggered by the Helmholtz “kink.”
The past, present, and future of acoustic cavitation nucleation
Authors: Atchley Anthony A.
Published: October 2005

Those familiar with the field do not need to be reminded that acoustic cavitation is the cornerstone of sonoluminescence and sonochemistry. However, an equally important and often overlooked statement is that nucleation is the cornerstone of acoustic cavitation. So critical is the nature of the nucleus to the cavitation process that the acoustic cavitation threshold in water can be varied from a few atmospheres to a few hundred atmospheres just by altering the distribution and properties of the nuclei. (The acoustic cavitation threshold is the maximum acoustic pressure amplitude to which a liquid can be exposed before cavitation inception.) The fundamentals of acoustic cavitation nucleation will be presented in this paper, which is intended to be tutorial in nature. Topics include homogeneous and heterogeneous nucleation, stabilization mechanisms, models of heterogeneous cavitation nuclei, and the dependence of the cavitation threshold on the properties of the nucleus. [Work supported by ONR and the NPS Res. Program]
The sonochemical hot spot
Authors: Suslick Kenneth S.
Published: October 2005

The origin of “sonochemistry” is acoustic cavitation: the formation, expansion, and implosive collapse of bubbles in liquids irradiated with ultrasound. The compression of such bubbles generates intense local heating, which has been quantified recently from both chemical kinetic thermometry and from high-resolution sonoluminescence spectra. The temperatures reached during cavitation are ≈5000 K, but have an effective lifetime of only a few microseconds. Consistent with this, the sonoluminescence that accompanies sonochemistry closely resembles flame emission! The chemistry generated by these hot spots is different than either ordinary thermal or photochemical processes and sonochemistry represents a fundamentally unique interaction of energy and matter. [For recent reviews see K. S. Suslick, Sci. Am. 260, 80 (Feb. 1989) and Science 247, 1439 (1990).] Recently, the use of ultrasound in liquid-powder slurries to enhance dramatically their chemical reactivity has been explored. For example, heterogeneous catalysis can be induced in normally nonreactive metals and the catalytic activity of Ni has been enhanced by 105. Using a variety of surface science techniques, it was shown that ultrasound removed the passivating oxide coating normally found on Ni and other metal surfaces, thus increasing their activity. The origin of these effects comes from extremely high-speed interparticle collisions which occur during ultrasonic irradiation of liquid-solid slurries. Turbulent flow and shockwaves produced by acoustic cavitation can drive metal particles together at sufficiently high velocities to induce melting upon collision. A series of transition metal powders have been used to probe the maximum temperatures and speeds reached during such interparticle collisions. Metal particles that are irradiated in hydrocarbon liquids with ultrasound undergo collisions at roughly half the speed of sound and generate localized effective temperatures between 2600°C and 3400°C at the point of impact. [Work supported by NSF and the UIUC Materials Res. Lab.]
J. C. R. Licklider, a remarkably versatile scientist
Authors: Pollack Irwin
Published: October 2005

An overview of the remarkably diverse scientific contributions of J. C. R. Licklider will be presented. Important contributions include: electrophysiology of the auditory cortex, design of speech communications systems, theories of hearing, human factors in command-control systems, the design of computers for human use, and the expedition of computer sciences as an academic discipline.
J. C. R. Licklider as a psychoacoustician
Authors: Kryter Karl D.
Published: October 2005

Licklider's training and experience as a mathematician, physicist, and psychologist provided the basis for a unique variety of scientific endeavors in the fields of audition and perception. Some selected early contributions of Licklider to physiological and psychological acoustics will be briefly reviewed.
Sharing place, period, and concepts with Licklider
Authors: Hirsh I. J. , Singh P. G.
Published: October 2005

The nature of pitch as a dual attribute comprising both “place” and “period” aspects was dramatically illustrated by Licklider [J. Acoust. Soc. Am. 26, 945 (1954)] in his famous masking demonstration. Listener confusions in judgments of pitch in subsequent experiments could be attributed to conflicting “place” and “period” information. Although the concept of pitch duality has been updated by pitch theorists, one aspect that has been consistently overlooked is the relation between “place” or “spectral” pitch and timbre. For example, the direction of a perceived pitch change is often confused with an ordinal aspect of timbre, like “brightness” and “sharpness.” The connection between “place” pitch and timbre will be discussed and demonstrated with examples from the literature and from our own experiments. [Work supported by USAFOSR and NIH.]
Interaural correlation and the discrimination of one from two delayed sources
Authors: Pollack Irwin
Published: October 2005

In 1948, J. C. R. Licklider provided a powerful methodology for exploring the binaural system in terms of the cross correlations of signals presented to the two ears. The Licklider procedure is here extended to the discrimination between: (1) a binaural source with single ongoing interaural delay and (2) a combination of two binaural sources, each with its own delay, with the mean delay equal to the single delay. Accuracy of discrimination suffers at longer mean interaural delays. Accuracy of performance varies with the difference between the two delays of the combination. The direction of change is determined by the contrast in interaural correlation. The results are consistent with a binaural system where interaural correlation is evaluated at stations specific to the component interaural delay(s); where the strength of interaction between the component correlations decreases with the difference in the component interaural delays; and where the associated internal noise level increases with longer interaural delays (Jeffress). Licklider's methods and his correlational theory of binaural localization continue to provide a rich source of hypotheses and procedures for the analysis of binaural listening.
Is human hearing limited by Brownian motion?
Authors: Green David M. , Dai Huanping
Published: October 2005

The normal human listener requires a signal energy to noise power density ratio (E/N0) of 10 to reliably detect a 1000-Hz signal presented in a wide band noise. Since it does not seem likely that the process of detecting a sinusoidal signal depends on whether or not the noise is audible, a natural question is whether the absolute hearing sensitivity is limited by molecular motion. According to Watson, Franks, and Hood (1972), who were the first to control the signal duration (125 ms), the absolute threshold at 1000 Hz is about 9 dB SPL. The energy of this signal is approximately 10−16 W s/cm2. We estimate the N0 of Brownian motion over the same area to be about 1.7 × 10 20W s/cm2. Thus, the ratio of signal energy to noise power density at absolute threshold is about 5000. Our ability to hear weak auditory signals is impressive, but the fundamental limitation is not the thermal agitation of molecules of the air. [This research is supported by the AFOSR.]
A neural network adaptive controller for nonlinear processes
Authors: Cabell Randolph H. , Fuller Chris R.
Published: October 2005

Numerical simulations were used to study the use of an artificial neural network (ANN) as an adaptive controller for nonlinear applications. This implementation is similar to those using the adaptive LMS algorithm; however, the neural network can be used with nonlinear systems. The network contained two layers of internal processing units (hidden units), and the connection weights between units were calculated using the backpropagation training algorithm. The neural network was trained to control two types of nonlinearities: a square wave and a biharmonic system. The neural network controller achieved 15-dB attenuation when tested on the biharmonic system. In some cases the network required excessive time to converge to a solution, and the solution was sensitive to the initial configuration of the network. in general, the ANN shows potential for controlling nonlinear processes; however, there are a number of problems to be resolved before successful applications are realized. [Work supported by ONR/DARPA and NASA.]
Profiling vectors for speaker identification
Authors: Hollien Harry , Jiang Ming
Published: October 2005

When speaker verification is the issue of interest, it is possible to focus on signal analysis irrespective of the speech related features it contains. Such approaches are appropriate in this case because system distortions are minimal, noise is low, talkers are cooperative, and very sophisticated equipment is available. Not so for speaker identification. Here extensive channel and speaker distortions (including noise) can be expected; speech is noncontemporary and speakers usually uncooperative. Hence, the signal is so distorted or masked, the usual processing techniques cannot be expected to be very useful. The approach to speaker identification demonstrated in this paper is threefold. First, it is assumed that the signal contains speech features that are robust (i.e., resistant to noise and distortion) and unique to the talker. These idiosyncracies are based on speaker's anatomy, physiology, and habitual communicative patterns. Second, it is postulated that, while there may be no single attribute within a person's speech/voice that would permit them to be differentiated from all other speakers under any set of conditions, the simultaneous use of a large series of feature analyses may permit identification. Finally, it has become possible to reduce bias among the vectors by the normalization of data. In turn, this approach leads to a very effective two-dimensional profile wherein the unknown speaker must first be identified and then comparisons made to known talkers. A system of this type has been structured and tested; it is based on four natural speech vectors, each containing 20–40 parameters. Data regarding this general approach and these vectors have been reported previously. This presentation will focus on the effects (on efficient speaker identification in the field) of normalizing the vector data and reducing it to a two-dimensional profile.
Vowel formant tracking for speaker identification
Authors: Jiang Ming , Shi Min
Published: October 2005

The first two or three spectral peaks, or formants, are crucial in determining the vowel quality. In turn, accurate determination vowel formants quality is important to effective speaker identification task. A vowel formant tracking vector (VFT) was developed for the speaker identification (SAUSI) profile. Specifically, the speech spectrum is obtained frame-by-frame by using an LPC algorithm with the first three formant frequencies for each frame calculated. The underlying assumption was that the vowels will exhibit a contiguous formant frequency transition from frame-to-frame and, hence, can be separated from consonants for the cited formant measurements. In order to carry out this task, the frequency range 0–5000 Hz is divided into 34 semitone bins and three histograms are obtained for first three vowel formants. In turn, these histograms provide an estimation of general quality of the vowels spoken by each speaker being evaluated. The result is that the interspeaker differences are large enough to permit identification of the target speaker while the intraspeaker differences are fairly small even for text independent speech. The algorithm utilized will be presented as will data demonstrating that this VFT vector is robust enough to effectively perform the speaker identification task.
Automatic speech recognition based on property detectors
Authors: Ananthapadmanabha T. V. , Jayasimha H. N.
Published: October 2005

Speaker-independent, large-vocabulary, continuous speech recognition by a machine is a challenging problem for which over a decade of search has been made without significant progress. In the existing systems, the same acoustic feature vector (LPC, cepstrum, filter bank, etc.) is used for all speech sounds and they heavily depend on contextual information for their success. This paper presents some results based on a radically different approach called “property detectors.” The approach of property detectors is well known in visual perception where it has been demonstrated that specialized detectors exist on the retina that trigger only for vertical, horizontal, or inclined lines. It has only been speculated that such specialized detectors could exist for speech. Recently, acoustic properties have been discovered that uniquely characterize some phonemes like /a/, /i/, /u/, /e/, /o/, and /s/. A limited-vocabulary, speaker-independent airline schedule announcement system was developed. This system was tested in a noisy hall with a large number of speakers, including female speakers, with different linguistic backgrounds. The system, though is in its early stage, gave a performance of about 85% accuracy. The approach based on property detectors aappears promising
Source parameters for the fricative consonants /s,∫,ç, x/
Authors: Shadle Christine H.
Published: October 2005

A series of experiments with mechanical models of fricative consonant articulatory configurations have been conducted to determine where in the tract the turbulence noise is generated and the spectral characteristics of that noise. The latest models, based on a combination of x ray, EPG, and photographic data, have the correct midsagittal profile and area function, and thus have the most realistic shape of model work to date. Data obtained from /s,∫/ substantiate earlier results based on a different subject [C. H. Shadle, J. Acoust. Soc. Am. Suppl. 1 84, S34 (1988); C. H. Shadle, in Speech Production and Speech Modelling, Proc. of NATO-ASI, edited by W. Hardcastle and A. Marchal (Kluwer Academic, Amsterdam, 1990), pp. 127–219] and results from extremely idealized models [C. H. Shadle, Proc. 12th ICA, paper A3-4, Toronto (1986)]. Comparisons across a range of flow rates, with and without sublingual cavity, between measured source and far-field spectra, and between speech and model data for /s,∫,c, x/ lead to source parameters, a distinction between two source types, and to the conclusion that the three-dimensional shape of the tract is crucial in determining source parameters: these parameters can be used in a model based on one-dimensional sound propagation. Three-way comparisons between far-field sound measured (1) for the models and (2) for actual utterances, and (3) far-field sound predicted from measured source parameters used in a model based on one-dimensional sound propagation, will be shown. [Work supported by SERC.]
High resolution and efficient oceanographic and acoustic modeling of propagation through mesoscale oceanic features
Authors: Gardiner L. S. , Frederick B. R. , Chmielewski T. A. , Bilazarian P. , Mitchell W. F.
Published: October 2005

A procedure is presented for combining the output of advanced multilevel “primitive equation” dynamic oceanographic forecast models with high fidelity underwater acoustic propagation models. This procedure is appropriate for the development of realistic predictions of acoustic transmissions through complicated mesoscale features, such as currents, rings, eddies, and fronts. Examples of oceanographic predictions using the Princeton dynamic ocean model developed by Mellor and Blumberg are displayed graphically for a dataset of the Gulf of Mexico. Results pertinent to data interpolation, the identification of mesoscale oceanic features, and 3-D visualization are presented. Ocean data are converted to sound-speed profiles for this region and are interfaced to a range-dependent parabolic equation (PE) propagation loss model. As a low-frequency acoustic source is moved successively from shallow to deep water in the Gulf of Mexico, results are given that illustrate large variations in propagation loss to a receiver located in deep water. The relative contributions of bathymetry and mesoscale oceanic features to these variations are analyzed. Finally, a scheme for speeding up PE calculations by utilizing the massively parallel computational capabilities of the Connection Machine at GE/ATL is discussed.
Generating eigenray tubes from two solutions of the wave equation
Authors: Bowlin James B.
Published: October 2005

A method is presented for calculating the paths taken by sound between a source and receiver. These paths, which are called eigenray tubes, are obtained from two solutions of the wave equation at finite frequency, one propagated from the source and the other propagated from the receiver. The results are not restricted to the high frequency limit as is the case with classical ray traces. This generalization of classical ray tracing could be an important new tool in acoustic tomography.
Hearing loss compensation—The defense prospective
Authors: Scheiner Richard W.
Published: October 2005

The lecture will focus on the current state of hearing loss claims in the workplace. The discussion will include the prevalence of hearing loss claims in heavy industry, the factors influencing the volume of claims including the influence of unions and organized labor, the feeling that these claims yield easy money, and the effect of the depressed economy. Information will be given regarding the cost factor of these claims to the employer and industry. The lecture will include an overview of the Longshore & Harbor Workers' Compensation Act (LHWCA) and certain portions of that law which play a strong part in the resolution of hearing loss claims including the last injurious exposure rule, the no apportionment rule, the effect of advancing age and/or retired workers on hearing loss claims, and the virtual elimination of the defenses of the statute of limitations and notice. Parallel comparison will be made to state workers' compensation acts focusing primarily on the State of Maryland. A review of the many factors which favor the claimant's position in hearing loss cases will be discussed. In addition, the lecture will review various legal tactics and theories used in defending hearing loss claims including some recent decisions under the Longshore & Harbor Workers Compensation Act which affect and may ultimately change defense tactics.
Hearing loss compensation from the corporate viewpoint
Authors: Guy M. Russell
Published: October 2005

Manufacturing operations are located mainly in three states which present widely varying requirements for hearing loss compensation; the compensation case experiences in these three jurisdictions will be discussed. The relationship of hearing loss compensation costs to total compensation costs will be presented. An explanation will be given on the approach utilized to address/handle hearing loss claims. The importance of preventing occupational hearing loss will be emphasized.
Hearing loss prevention—Worker's responsibilities
Authors: Detwiler James E.
Published: October 2005

One element of hearing loss prevention that management often feels it cannot effectively control is worker's actions and responsibilities. The solution to this problem is the development and enforcement of effective management-backed employee policies covering each hearing conservation issue. It is absolutely vital that all such policies be in writing and that they be clear, reasonable, sensible, and enforceable. Principal program elements that need written policies are monitoring, engineering and administrative controls, personal hearing protection devices, training and education, audiometric testing, and supervisors' responsibilities in program administration. Under each program element, one or more specific policy objectives should be spelled out, with each objective followed by a detailed policy statement of the actions or behavior required to meet that objective. Numerous examples of policy objectives and statements were written for each of the principal program elements. Finally, for the policies to be enforceable, there must be in place a fair and consistent system of discipline. Properly written and enforced policies are not designed to restrict the individual, but to protect him by assuring him safe working conditions and equal treatment with his fellows.
Mining occupations with high incidence rates for noise-induced hearing loss
Authors: Valoski Michael P.
Published: October 2005

The Mine Safety and Health Administration (MSHA) requires that mine operators report to MSHA all cases of diagnosed or compensated occupational illness. Listed among the examples of reportable occupational illnesses is noise-induced hearing loss (NIHL). All cases of occupational hearing loss reported to MSHA between 1986 and 1989 (1288 cases) were examined. After separating the hearing loss cases by causal factor, a population of 1264 cases of NIHL remained for retrospective study. This study was conducted to identify those occupations which had substantially larger numbers of NIHL cases or higher incidence rates of NIHL. The NIHL cases were separated by coal (1030 cases) and metal/nonmetal mining (234 cases). The population data were obtained from a Bureau of Mines database. Since this database only contained data on occupational groups, not individual occupations, the incidence rates were calculated for occupational groups. The continuous miner and related machine operator occupational group had both the most cases of NIHL and the highest incidence rate for coal mining. While for metal/nonmetal mining, the mechanic-welder-oiler-machinist occupational group had the most cases of NIHL and the shuttle car-tram operator occupational group had the highest incidence rate. The work location which had the highest incidence rate of NIHL was preparation facilities for coal mining and underground mines for metal/nonmetal mining.
Maximizing communication ability in the selection of hearing protective devices
Authors: Williams Dennis , Michael Kevin
Published: October 2005

The most common procedure for selecting hearing protective devices (HPDs) is the Noise Reduction Rating (NRR). The NRR can be misleading and often results in the selection of HPDs that either under- or over-protect the wearer. The wearer of an under-protective HPD is likely to experience noise-induced hearing loss. The use of over-protective HPDs can needlessly reduce speech communication, the ability to hear warning signals, and the ability to recognize important machine sounds. Workers fit with over-protective HPDs are also less likely to properly wear their HPDs. An articulation index (AI) based method of ranking HPDs for use in specific noise exposures was developed in conjunction with the American Iron and Steel Institute (AISI). The calculations used in the procedure incorporate the attenuation characteristics of the HPD, the spectrum of the noise source, the hearing thresholds of the wearer, the nonlinear growth of masking, and the predicted level of speech in noise. The HPD rankings are intended to insure that adequate attenuation and optimum communication ability is achieved.
Seafloor shear wave velocity structure determined from interface wave dispersion
Authors: Dorman LeRoy M. , Schreiner Anthony E. , Bibee L. D.
Published: October 2005

The propagation of interface waves in the seafloor waveguide is primarily controlled by the sediment shear velocity, which increases rapidly with subbottom depth. This gradient causes the propagation velocity to be strongly frequency dependent and this dispersion allows one to infer the shear velocity structure from propagation velocity measurements. These waves were excited with small explosions on the seafloor and the dispersion was measured over distances of a few hundred meters, observing seafloor motion on ocean bottom seismographs (OBSs). It is common to observe these waves in the 0.5–5 Hz frequency range, even from explosions with bubble frequencies in the 100- to 400-Hz range. Typically several modes are seen and shear velocity in the 1- to 30-m depth range can be recovered. The attenuation is high (Q = 25) in the very near surface, consequently, modes with large energy just below the surface suffer severe attenuation, while modes with little energy in the highly absorbing regions (higher modes and all modes whose phase velocity is near that of water) show Q up to 500. [Work supported by ONR.]
Remote sensing of sediment properties using seafloor arrays
Authors: Stoll Robert D.
Published: October 2005

The placement of both source and receiver on the seafloor yields significant advantages when measuring the geoacoustic properties of near-bottom sediments. Moreover, by using multiple receivers in an array and specifically designed sources that focus energy into the bottom and minimize the water-borne “noise,” it is possible to measure both p- and s-wave properties in significant detail. In this paper a detailed example of this technique illustrating equipment design, data acquisition, and inversion of data to obtain a geoacoustic model is presented. Results show that the horizontal component of motion contains important information that cannot be derived easily from hydrophone or vertical motion data. In addition, both near-field and far-field data are shown to be complementary in determining near-bottom, high-resolution models.
Application of remote sensing and in situ measurements of ocean sediment properties to the prediction of acoustic propagation loss
Authors: Akal T. , Caiti A. , Ingenito F. , Kristensen A.
Published: October 2005

An experiment was conducted in the Adriatic Sea to evaluate the ability of geophysical models of the ocean bottom, constructed by the application of in situ and remote sensing measurement techniques, to predict acoustic propagation loss. Short-range wide-angle measurements of acoustic reflection from the bottom and measurements of the dispersive characteristics of seismic interface waves at the water-sediment boundary are used to estimate the P- and S-velocity profiles in the upper 30 to 50 m of the bottom sediment. Pointwise in situ and core measurements were taken at the same site. Simultaneously, broadband propagation loss measurements were made. Geophysical models were constructed from the bottom measurements and used as inputs to state-of-the-art acoustic models to predict propagation loss. Satisfactory agreement between measured and predicted propagation loss was obtained, indicating the general validity of the procedure.
Experimental verifications of bottom shear modulus profiler (BSMP) method
Authors: Yamamoto Tokuo , Trevorrow Mark
Published: October 2005

By measuring the response of a seabed to the pressure forcing of traveling ocean waves, the seabed shear modulus profile can be extracted by solving a geophysical inverse problem [Yamamoto and Torii, Geophys. J. R. Astron. Soc. 85, 413–431 (1986)]. The experimental results as favorably compared with geological boreholes have been reported [Yamamoto et al., Geophys. J. Int. 98, 173–182 (1989)]. ONR multi-institutional experiments were recently conducted to compare the various experimental methods for measuring the seabed shear properties at several sites on the continental shelf of the northeastern United States. Comparisons between the BSMP results and the SH wave refraction results by J. I. Ewing will be reported in this paper. Generally, good agreements between the two methods are obtained. BSMP method penetrates 200 m below seafloor (b.s.f.) at resolution of a few meters while the SH wave seismic method penetrates 50 m b.s.f. at approximately the same resolution. As an example application of the BSMP results to modeling, comparisons between model predictions (using BSMP data), and propagation experiments of seismic waves and acoustic waves in the ocean by W. Carey and the present authors are also made, resulting in favorable agreements. [Work sponsored by ONR.]
Near surface measurements of sediment geoacoustic properties using in situ probes
Authors: Richardson Michael D.
Published: October 2005

In situ and laboratory measurements of sediment geoacoustic properties together with sediment physical property measurements were made over the range of sediment types commonly encountered on continental shelves. In situ compressional wave velocities ranged from 1464 m/s in soft silty-clay sediments to as high as 1989 m/s in gravels. Velocities in sands were 1600–1700 m/s. Compressional wave attenuations (measured at 58 kHz of 4–12 dB/m were common in soft silty-clay sediments with higher attenuations of near 30 dB/m measured at sandy sites. In situ shear wave velocities ranged from 16 m/s in soft silty-clay sediments to 90 m/s in hard packed fine sands. Differences among in situ and laboratory values of sediment geoacoustic properties are discussed. Empirical relationships between sediment geoacoustic and physical properties are presented.