bluuebunny/crossref_metadata_2025 huggingface dataset:
Potential impact on sea turtles, dolphins, and fishes of explosives used in offshore platform removals
Authors: Klima Edward F. , Gitschlag Gregg R. , Renaud Maurice L. , Cummings William C.
Published: October 2005

A high incidence of strandings of sea turtles, bottlenose dolphins, and fishes was recorded on the beaches in the northwestern Gulf of Mexico during March–June 1986, when explosives were used to remove several oil platforms in adjacent offshore waters. Prior to, during, and after March–June of the following year, 1987, strandings for the same area were significantly lower, or negligible. Recovery locations of drift bottles released at the site of the explosions were correlated with some of the strandings. Wild turtles and bottlenose dolphins were observed in the vicinity of the platforms during removal operations. Abnormal (stunted) Kemp's ridley and loggerhead sea turtles were placed at various distances from platforms and exposed to explosions. Preliminary results from exposure studies, including the death of a Kemp's ridley 50 yards from the explosion and an unconscious loggerhead turtle approximately 1000 yards from the explosion, are described. Allowing for in-bottom loss, received sound-pressure levels were calculated to be 235 dB (50 yards) and greater than 200 dB where a caged loggerhead was found unconscious.
The influence of sound propagation conditions on the behavioral response of whales to underwater industrial noise
Authors: Malme Charles I. , Miles Paul R.
Published: October 2005

Results of recent studies involving gray, humpback, and bowhead whales show that whales tend to avoid areas with high underwater noise levels. Data obtained from whale behavioral observations during controlled exposure to representative industrial noise sources permit determination of the probability of avoidance Pa of the source region as a function of the noise level Ln. The zone of influence of a source may be defined as the region where Pa > 0.5. While the Ln required to produce this degree of avoidance has been found to depend on whale species and source type, some generalizations may be made. For low-frequency continuous noise, 50% of the whales exposed have been observed to avoid regions where the overall Ln is higher than 115 to 125 dB (re: 1 μPa). Sound transmission conditions at a specific site determine the distance from the source, where Ln falls below the Pa = 0.5 criterion level. The zone of influence thus has been found to vary considerably for the test sites investigated. For example, a drillship operating at a test site off the Alaskan Beaufort coast has an estimated zone of influence radius of 4 km, but, off the coast of California, the estimated zone of influence radius is reduced to 1 km. [Work sponsored by the Minerals Management Service.]
Effects of noise of a proposed ocean thermal energy conversion plant on marine animals—A preliminary estimate
Authors: Gales Robert S. , Moore Sue E. , Friedl William A. , Rucker James
Published: October 2005

An analysis is presented of the predicted underwater noise from a proposed 40-MW ocean thermal energy conversion (OTEC) plant to be located approximately 14 mile offshore of Kahe Point, Oahu, Hawaii, and its potential effects on the marine animals of the area. The required total warm and cold seawater flow of approximately 1.6 million liters/min involves 16 pumps driven by a total of 17 000 horsepower. Earlier studies [C P. Janota and D. E. Thompson, J. Acoust. Soc. Am. 74, 256–266 (1983)] calculated the noise generated by various proposed OTEC systems, and compared it with actual measurements on a 1-MW research system (OTEC-1) operating off Hawaii. These analytic procedures are utilized to predict the noise for the 40-MW plant. Underwater noise generated during the construction phase is expected to exceed the plant noise, but for a relatively short period. General auditory perception and expected responses of cetaceans and fishes of the area to both plant operation and construction noises are discussed. The most likely behavioral responses include temporary displacement from the area of the plant and partial masking of communicative signals. [Work supported by NOAA.]
Acoustic communication in P. Tigris
Authors: Hollien Harry
Published: October 2005

While no other species exhibits the extensive language systems of humans, a number are seen to pass information by one or more behaviors. Prominent among the observed signals are those of an acoustic nature; indeed, some subspecies of birds demonstrate fairly complex communicative networks. Among the Panthera, P. Tigris is perhaps the most vocal. Extensive S/R experimentation with seven captive tigers and subjective observation of nine others (plus evaluation of a few calls recorded in the field), have resulted in classification of ten meaningful utterances plus two others that may be information bearing (not yet “decoded”). This system appears to be somewhat more complex than that exhibited by Tursiops T. (and certainly more so than that of the common dolphin). The second stage of this project involves playback of recorded and synthesized calls in order to confirm (or not) the behaviors noted.
Towards a method for predicting absorption coefficient rather than measuring it in a reverberation chamber
Authors: Nicolas J.
Published: October 2005

The modelization of the impedance of fibrous and rigid process material is discussed. For fibrous soft material such as fiberglass, it will be shown that Delany and Bazley's model [Appl. Acoust. 3, 105–116 (1970)] is quite reliable for normal specific impedance as well as for oblique incidence. Experimental validations are done via the two-microphone method [submitted (1987)] (normal and oblique) and via the indirect method of the equivalent flow resistivity (oblique only). Performance of less classical types of soft material like felt is not well quantified by Delany and Bazley, showing clearly the limitation of this one-parameter model. For rigid porous material, the impedance behavior is generally more complex. Products like ceramics and cement-wood fiber have been under investigation. Flow resistivity, porosity, and tortuosity have been measured and introduced in Attenborough's four-parameter model [J. Acoust. Soc. Am. 73, 785–799 (1983)]. This leaves a not easily measurable parameter, the shape factor, which is used as an adjustable parameter. For these rigid materials, good agreement will be found between prediction and experimental data even for the important oscillations encountered for high frequency. This indicates that, with simple setups for the measurement of physical parameter, one may be able to calculate absorption coefficient rather than measuring it especially for normal incidence. However, the link between a calculated diffuse field absorption coefficient and the one measured in a reverberation chamber is not clear at present.
Effect of backlash on vibration spectrum in gear boxes
Authors: Moustafa M. , Shabara M. , Abo-Mosallam Y. , Al-Saeidy F.
Published: October 2005

An ideal gear box would produce no vibration at all because all energy would be channeled into the work to be done; but a well-designed gear box will produce low levels of inherent vibration. As the gear teeth wear, however, backlash between meshing teeth increases and this is reflected in an increase in the vibration energy. As the vibration energy is dissipated through the gear box, it excites resonances and exerts extra dynamic loads on gear teeth. It is of great interest to the maintenance engineers to predict the occurrence of backlash between gear teeth. The fact that vibration signals carry much information relating to running conditions of gear boxes can be used to solve this problem. In this study, a mathematical model was formulated to simulate the effect of backlash between gear teeth on the vibration spectrum of gear boxes. A single stage helical gear box was used to demonstrate this model. In this simulation, the transmission shafts were treated as lumped parameter systems. The elasticity of shafts, bearings, and gear teeth were also included. The grounded-chair representation was used to obtain the equations of motion that were solved using the Runge-Kutta method. The vibration spectra of the gear box system were obtained using fast Fourier transform (FFT). These spectra can be used to construct a vibration chart which, in turn, can be used to determine the proper times for maintenance of gear boxes to avoid failure of such units.
Matched-field processing and the effect of realistic noise correlation models
Authors: Zala Cedric A. , Ozard John M. , Milinazzo Fausto
Published: October 2005

In simulating acoustic source localization by matched-field processing, it is desirable to use a realistic ambient noise model. Two general classes of noise model were considered: a planar isotropic noise source distribution and a line source distribution. The former was implemented based on the work of Kuperman and Ingenito [J. Acoust. Soc. Am. 67, 1988–1996 (1980)]. Their expressions for the correlation integrals were adapted to compute the correlation function for both simple and realistic propagation models, through the use of analytical and numerical Green's functions, respectively. The line source model involved the assumption of uncorrelated noise sources along an infinite line and was designed to model a shear zone in a shallow ice-covered ocean. Using the corresponding Green's functions for a waveguide, the line model correlation function could be reduced to a summation over all mode pairs, each term of which involved an integration over wavenumber. In this paper, the line source correlation model is presented and correlation functions given by both noise models are illustrated. The effect of using these models on the localization of a discrete source by a grid search-optimization procedure is then examined.
Noise and array configuration considerations for matched-field processing in phone and mode space
Authors: Frichter G. M. , Del Balzo D. R.
Published: October 2005

The conditions under which mode space matched-field processing offers performance gains relative to phone space matched-field processing are investigated. Particular emphasis is placed on determining the effects of spatially correlated versus spatially uncorrelated noise fields and choice of array configuration on signal detection. Varying amounts of homogeneous white noise and spatially correlated noise as calculated by a normal mode noise model were combined with the field due to a submerged source to produce simulated phone space covariance matrices for a range of array configuration parameters. A phone-to-mode spacing mapping was then used to obtain the corresponding cross-amplitude correlation matrices. The results of both conventional and MLM processing were analyzed and the trade-off between the number of phones and percent of the water column spand was investigated.
Scattering from slots
Authors: Smith Marian
Published: October 2005

The effect of slots in boundaries on scattered radiation is a classical problem, yet one which is still of considerable interest. This paper presents an extension of prior work by the author [J. Sound Vib. (to be published July 1988)], which considered the effect of covering only the long wavelength approximation, where the slot width was much smaller than the wavelength of the incident radiation. This paper presents a more general method for the calculation of scattering from slots, which allows for solutions for larger slots, limited only by resonance considerations and computer size. Examples of solutions for scattering from slots in rigid walled plates, ducts, and cavities are presented. The method reduces the scattering problem, by means of the Green's function techniques, to an integral or integrodifferential equation. The resulting equation can be solved by numerical methods.
MACSYMA automated symbolic mathematics software
Authors: Petti Richard
Published: October 2005

Just as computers revolutionized numerical analysis, so symbolic mathematics software is revolutionizing symbolic mathematics computations, yielding major increases in speed accuracy and modeling power in many applications. In addition to automating large and tedious computations, MACSYMA provides automated mathematical expertise in many areas, such as solution of simultaneous equations, integration, Laplace transforms, ordinary differential equations, and simplifications of expressions. The presentations will focus on selected capabilities of MACSYMA that are relevant for acoustics, especially: (1) symbolic vector and tensor calculus, (2) symbolic solution of ordinary differential equations, (3) symbolic approximation methods, (4) use of symbolic math software to generate numerical analysis code, (5) symbolic matrix computations. A partial bibliography of research papers in fluid mechanics reporting on work where MACSYMA was used will also be provided. Also discussed will be the role of symbolic mathematics software in technical education.
Use of symbolic manipulation in physical acoustics
Authors: Manley Martin , Mehta Vineet
Published: October 2005

The development of a mathematical theory in acoustics (or in any other field) depends on the insight of the theoretician. However, the formulation of an insight into an equation derived from first principles involves much time spent in activities that fall within the category of a symbolic manipulation. To demonstrate the role symbolic manipulation software can play in the solution process, classical problems in acoustics will be selected. It is known that the solution to the linearized governing equations of an acoustic field can be considered as a superposition of vorticity, thermal, and acoustic modes. However, these modes are coupled. The separation of these modes will be demonstrated. Symbolic manipulation will be used to explore how the higher-order terms in the perturbation parameters, εμ, and εκ, affect the modal coupling. The issue of asymptotic degeneracy will also be addressed (the effects of varying the rates at which these parameters approach zero).
An evaluation of an intelligent computer service assistant
Authors: Armstrong Paul W. , LaRue Dan
Published: October 2005

This presentation will discuss the development issues required for the implementation of an intelligent assistant for Apollo's customer service organization. An overview of the design and requirement goals as well as the integration with current data systems and input will be addressed. Maintenance and future enhancemerits will be reviewed as well as a discussion of the user interface and user profiles.
Enhanced nonlinearity in a bubbly liquid considered as a mixture
Authors: Everbach Erich Carr , Apfel Robert E.
Published: October 2005

During the past decade there has been an increasing interest in the nonlinear behavior of gas bubbles in liquids. Recent papers by Soviet investigators [e.g., Kustov et al., Sov. Phys. Acoust. 32(6), 500–503 (1986)] have concentrated on phenomena observed when sound interacts with a bubbly layer. These phenomena can include acoustic solitons, parametric radiation, self-focusing, phase conjugation, and other effects that occur because the system is highly nonlinear. An investigation of the acoustic nonlinear parameter of mixtures was conducted to help infer the volume fractions of the mixture components. When a bubbly medium of known air volume fraction is considered as a two-component mixture, its effective nonlinear parameter may be calculated using mixture methodologies [R. Apfel, J. Acoust. Soc. Am. 74, 1866–1869 (1983)]. The mixture analysis in this work, which is independent of any assumptions regarding bubble oscillation, yields nonlinear parameter values comparable to those of the Soviet investigators. For certain volume fractions, values of the nonlinear parameter of a bubbly liquid may be hundreds of times that of either the gas or the liquid host. Both experimental and theoretical work will be presented and the implications of this enhanced nonlinearity will be discussed. [Work supported by NIH through Grant 5-R01-GM30419.]
Kirchhoff approximation for scattering from a rough fluid-solid interface
Authors: Dacol Dalcio K.
Published: October 2005

A general prescription for the Kirchhoff approximation for wave scattering from a penetrable surface is implemented for the case of acoustic scattering from a rough fluid-elastic solid interface. A simpler version developed from this prescription produces results that compare favorably with exact numerical results for the case of simple periodic fluid-solid interfaces. This approximation is well suited to describe sound scattering from a randomly rough fluid-solid interface. In this case, the results obtained using this approximation are compared with those from a previously developed renormalized perturbation theory. Overall, this approximation is satisfactory but, since it is a single scattering theory, it fails to incorporate multiple scattering effects that are small in its domain of validity.
Ultrasonic attenuation coefficient assessment in rat liver from carbon tetrachloride
Authors: Boatright David J. , O'Brien William D. , Erdman J. W.
Published: October 2005

The ultrasonic attenuation coefficient is examined in rat liver due to the effects of inhalation of carbon tetrachloride using the insertion-loss technique @ 1.38:5, 4.210, 7.015, and 9.820 MHz; it is theorized that rat livers will develop an increase of collagen. Tissue constitutes of glycogen, protein, and water concentration are assessed. The concentration of these tissue constitutes over an 11-week period on the carbon tetrachloride compared to the attenuation coefficients at the four frequencies suggest ultrasonic properties can be modeled as a function of constitute concentrations. At 1.385 MHz, the attenuation coefficient is statistically significant as a function of glycogen, water, and protein. At 4.210 MHz, only protein is statistically significant; at 7.015 MHz, both glycogen and protein are statistically significant; and at 9.82 MHz, none of the tissue properties is shown to be significant with respect to the attenuation coefficient. [Supported by NIH Grant CA 36029.]
Fluid mechanics of the velopharyngeal tract
Authors: Scherer Ronald C.
Published: October 2005

Prediction of geometrical characteristics of the velopharyngeal tract (VPT) during speech would aid in determining speech adequacy and intervention effectiveness. Earlier work [beginning with D. W. Warren and A. B. DuBois, Cleft. Pal. J. 1, 52–71 (1964)] attempted to predict cross-sectional area of the VPT from measurements of mean flow through the tract and mean pressure drop across the tract by using a discharge coefficient (DC) expression where the DC is constant. In this study, the assumption of a constant DC is challenged through the use of a theoretical equation applicable to similar air channels. The equation takes into account the geometry of the VPT, and includes kinetic pressure terms for the VPT entrance and exit and a viscous pressure term for the duct. The predicted DC significantly increases with Reynolds number (Re) (especially below 1000), asymptotes to higher values for larger VPT cross-sectional area, and is most sensitive to geometry change for low Re. The predicted DC is higher than found in earlier modeling studies. Results suggest that earlier physical models were too simple and further empirical study is justified.
Native speakers of Spanish and English compensate equally well for a bite block in producing vowels
Authors: Flege J. E.
Published: October 2005

A recent detailed study [Flege et al., J. Acoust. Soc. Am. 83, 212–228 (1988)] provided auditory and acoustic evidence that talkers do not compensate completely or instantly when producing vowels with a bite block. This study examined compensation physiologically. Adult native speakers of English and Spanish produced nonsense disyllables (/bVba/) in a Spanish or English carrier phrase. Glossometry was used to measure the vertical distance of the tongue from the hard palate at four sensor locations in multiple productions of the stressed vowels /i/, /e/, /a/, /o/, and /u/. Even though Spanish has fewer vowel categories than English (5 vs 15), the Spanish and English subjects showed equal variability in tongue positions (standard deviations of 0.746 and 0.756 ram). The subjects in both groups showed significantly greater variability in the bite-block than normal-speech condition (means s.d.'s of 0.821 vs 0.722 mm). There were clear differences in the average tongue positions for Spanish and English vowels spoken normally. The eight subjects in both groups showed tongue position differences (unsigned) of only about 1 mm when producing vowels normally and with a bite block. The effect of condition on tongue positions was not significant for either group. [Work supported by NIH.]
Intonational and rhythmic correlates of stress clash
Authors: Beckman Mary , deJong Kenneth , Edwards Jan
Published: October 2005

Phonologists support a directly metrical representation of stress rhythms by observing that when one stress “beat” follows closely on another, the rhythmic clash seems to be remedied either by retracting the first stress, as in Chinese exports, or by increasing the interstress interval, so that the pop of pop posed is longer than that of poppa posed. Cooper and Eady [J. Mem. Lang. 25, 369–384 (1986)] have questioned the empirical validity of such observations by showing that the first syllable's duration is not longer in phrases where stress should have retracted to it; nor is it longer in Chris Mack compared to Chris MacKensie. Recent experiments, however, support the notion of rhythmic clash even if the precise formulation of metrical phonologists is wrong. It was found (1) that syllables perceived as bearing a retracted stress have longer durations relative to the less stressed following syllable, (2) that phrases with retracted stress have different distributions of pitch accents in the intonation pattern, and (3) that although the pop of pop posed is not longer than that of pop opposed, it is longer than that of poppa posed. These results are used to support an indirect metrical representation in which stress patterns are read from a prosodic constituent tree that includes intonational structure.
Intracochlear pressures resulting from brief high intensity stimuli
Authors: Patterson James H. , Mozo Ben T. , Buck Karl , Decory Laurent
Published: October 2005

A previous study has shown similar hearing loss and cochlear injury from exposures to impulses differing in peak pressure, but having the same energy and Fourier pressure spectrum. Nonlinear processes in the middle ear or transmission through the external and middle ear may render different stimuli more similar once they reach the cochlea, thus accounting for the equivalent injury observed. In order to explore this possibility, pressures in the basal turn of the cochleas of eight anesthetized chinchillas were measured for impulses presented at levels between 88-and 147-dB peak. This included the impulses used in the previous injury study. While nonlinearities were noted at the higher intensities, there was a remarkable preservation of the pressure-time histories. In addition to these impulse stimuli, intracochlear pressures were measured using brief tone pips whose envelope was Gaussian. Frequencies of 700, 1375, 2000, 2700, and 4100 Hz were chosen to span the frequency response of the speaker. With these stimuli, nonlinearities appeared as both harmonic and subharmonic distortion as the intensities increased.
The time-marched FFP for modeling ocean acoustic pulse propagation
Authors: Porter Michael B.
Published: October 2005

Traditional ocean acoustic models for cw (time-harmonic) signals may be extended in an obvious fashion for broadband problems using Fourier synthesis. Alternatively, many of these models may also be solved directly in the time domain that raises the questions of what is the optimal solution and under what conditions. A time-marched fast-field program has been developed in which the solution is represented as a sum of Fourier components in range with time and depth-dependent amplitudes, ɑ(z,t;k). These amplitudes each satisfy a simple hyperbolic equation that is discretized in depth using finite elements and in time by a simple explicit integrator. Snapshots of the ocean acoustic field are then obtained in the usual fashion using an FFT to assemble the various spatial Fourier components. Examples of the method applied to pulse propagation in certain ocean acoustic scenarios will be presented with particular regard to the question of the strengths and weaknesses of the time-marched FFP versus synthesis from time-harmonic FFP solutions.
On the structural-acoustic design of guitars
Authors: Davis Evan B.
Published: October 2005

A structural-acoustic model of a guitar top plate backed by a rigid cavity has been built. Acoustic coupling between the interior and exterior acoustic fields is accomplished with a simple model of the soundhole. Acoustic power spectra are calculated in 1/12 octave intervals from 55 to 440 Hz. The soundboard is modeled as an orthotropic damped plate with reinforcing beams and a circular cutout forced by harmonic point loads representing the strings. The model requires the plate outline to be axisymmetric. There are no limitations on the number or orientation of the reinforcing beams. Material property variations, brace cross section, brace pattern layouts, individual brace tapers, plate thickness, and varnish and glue line effects can be studied with this model. A suitable database of material properties and guitar geometry parameters, string lengths, bridge placements, etc. has been built to support the model.
A model analysis of force-deformation characteristics of a piano hammer
Authors: Suzuki Hideo
Published: October 2005

Effects of a geometry and a Young's modulus profile of a piano hammer on its static force-deformation characteristics are studied using a finite element mode. The material properties of the model are assumed to be linear as well as isotropic. Therefore, only a geometric nonlinearity is considered. A hammer model with a representative geometry and Young's modulus profile of an actual bass hammer has a force (f)-deformation (d) relationship approximated by a function, f = AdB , with approximately B = 1.7. On the other hand, the degree of nonlinearity (B) of a particular hammer obtained from a dynamic measurement is approximately 2.3 or larger. A hammer with a larger increase of Young's modulus in the inward direction has a larger degree of nonlinearity. The geometry of a hammer has a large effect on the value A in the formula shown above. A hammer with a shorter height (distance from the top of the hammer to the top of the wood piece) or with a larger width has a larger value of A (in other words, a larger stiffness).
Influence of bore shape on the resonant frequencies and spectral envelope of a French horn
Authors: Dudley J. Duane , Strong William J.
Published: October 2005

The harmonicity of the resonant frequencies, and the shape of the spectral envelope of the input impedance curve, are two important indicators that might be used in predicting the usefulness of a given air column as a brass wind instrument. These can be determined by approximating the air column as a large number of concatenated lossy cylindrical increments, and computing and plotting the input impedance of the configuration as a function of frequency. In this paper the results of such calculations are described for a number of bore shapes related to the French horn, and the effects of changing various dimensional parameters are illustrated. The contributions of the bell, the leadpipe, and the mouthpiece of a typical open B-flat horn are first examined. Then the horn is idealized and represented by 14 dimensional parameters, so that each can be varied independently to study its effects on harmonicity and spectral envelope, and an optimum configuration is determined. Finally, the effects of inserting the hand into the bell are examined.
Woodwind instrument simulation in real-time
Authors: Park Michael , Keefe Douglas H.
Published: October 2005

A real-time implementation of the McIntyre-Schumacher-Woodhouse time-domain description of musical oscillators (1983) has been developed using digital signal processing (DSP) hardware. The system is comprised of a microcomputer with installed DSP board including a digital-to-analog converter. The task is to perform a convolution and solve two simultaneous equations with nonlinearities for the unknown pressure and volume flow at successive instants of time. A table lookup with linear interpolation simplifies the original formulation. The reflection functions used in the convolution are calculated based upon analytical models of woodwinds, but the nonlinear valving mechanism is somewhat idealized. One can “play” the instrument via an MIDI keyboard controller. Each MIDI note-on message loads a different reflection function into the DSP board memory, while the pitch wheel controls “blowing pressure.” Recorded examples will be presented.
Patterns of expressive timing in performances of a Beethoven Minuet by nineteen famous pianists and one computer
Authors: Repp Bruno H.
Published: October 2005

Onset-to-onset durations of quarter notes and sixteenth notes were ‘measured in nineteen complete performances of the third movement of Beethoven's Piano Sonata op. 31, No. 3. These measurements were compared to those from a computer performance incorporating the “Beethoven pulse” expressive microstructure devised by Manfred Clynes [U.S. Patent No. 4,704,682 (1987)]. This pulse is a particular pattern of relative note durations (and amplitudes) within successive time units, and it is designed to be invariant except for occasional larger deviations at structurally salient points. Although patterns resembling the Beethoven pulse could be found locally in the human performances, on the whole there was little evidence for a fixed, pulselike pattern of timing deviations. Rather, the measurements suggest that great artists change the patterns of relative note durations continuously to meet the local expressive requirements of the composition, and that, despite considerable individual differences, there is some consensus about what these requirements are. If the invariant Beethoven pulse enhances the expressiveness of the computer performance, as it seems to do [B. H. Repp, J. Acoust. Soc. Am. Suppl. 181, S92 (1987)], this is apparently not because it captures aspects of human performance. [Work supported by NIH.]
Creating a sound field for manipulating interaural level differences separately or independently of the interaural time differences and vice versa
Authors: Kuhn George F.
Published: October 2005

Using two or more sources whose source strengths and relative phases can be controlled independently, a sound field can be generated in which the interaural pressure level differences (ILDs) and the interaural time differences (ITDs) can be controlled separately. Thus, for a fixed ILD, a range of ITDs, or vice versa, can be presented to the listener. Thus it appears possible to perform some localization experiments that had previously been confined to lateralization methods using earphones. Some calculated results for interaural time differences and interaural level differences, using two sources, will be presented.
Intensity measurements for interior noise control
Authors: Cohen Robert L.
Published: October 2005

Typical noise sources, purposes of making intensity measurements, and difficulties in making useful intensity measurements in jet aircraft interiors are surveyed. Primary noise sources contributing to cabin interior noise are boundary layer, air conditioning, engines, and machinery. Transmission paths include both air and structure. Primary applications of intensity measurements in evaluating and controlling the effects of these sources on cabin noise include (1) locating and ranking sources for noise reduction; (2) optimizing acoustic treatment for minimizing weight; (3) providing data in support of cabin noise predictions related to planned changes in structure or acoustic treatment; and (4) transmission loss measurements for evaluating and improving sidewall panel acoustic effectiveness. Measurement difficulties include limited flight time, requirements for sampling detail in unknown gradients across each surface, unknown surface absorption, and unknown background noise levels interfering with the measurement of surface radiation, determining the accuracy of each measurement, and interpreting the data especially as a function of data quality.
High-frequency intensity-ealibrated threshold measurements using a two-microphone system
Authors: Murphy William J. , Tubis Arnold , Long Glenis R.
Published: October 2005

As a means of calibrating high-frequency hearing tests without the problems inherent in the use of pressure-calibrated headphone systems [M. R. Stinson, J. Acoust. Soc. Am. Suppl. 1 87, S75 (1987)], an intensity-calibrated method of measuring hearing thresholds based on the two-microphone technique has been developed [W. J. Murphy, A. Tubis, and G. R. Long, J. Acoust. Soc. Am. Suppl. 1 87, S75 (1987)]. The two-microphone probe is used to estimate the acoustic impedance and the power reflection coefficient of the middle and inner ear system as well as to calibrate psychoacoustic measurements. Various cheeks on the reliability of the long-term phase calibration are discussed. A computer simulation of the ear canal acoustics is used to determine an appropriate downstream distance of the probe tips from the insert-earmold sound port. Typical data are given for both objective and psychoacoustic measures obtained with the two-microphone system. [Work supported by a grant from the Deafness Research Foundation.]
Reciprocity calibration of an underwater transducer by the Delta-Z method
Authors: Bedard R. , Baker S. R.
Published: October 2005

A method for determining the free-field open-circuit voltage sensitivity of a reversible underwater electroacoustic transducer from the difference in its input electrical impedance when loaded by water and air was investigated theoretically and experimentally. An equation for the sensitivity was derived using reciprocal two-port network theory. The theory takes into account the diffraction due to the finite size of the transducer, its finite mechanical impedance, and its free-field radiation impedance in water. An experiment to test the predictions of the theory was performed using a 6-in.-diam, hollow, piezoelectric ceramic spherical transducer. The results of the experiment agreed within several dB with the results of a standard comparison calibration over the frequency range for which both the electrical impedance and comparison calibration data are considered reliable. The calibration method described, which has been termed the Delta-Z method, may be useful for in situ monitoring of transducer sensitivity in installations which can be flooded and purged. Major, Canadian Armed Forces. Permanent address: 415 Squadron, C. F. B. Greenwood, Nova Scotia BOP 1N0, Canada.
A four-sided flextensional transducer
Authors: Butler John L. , Rolt Kenneth D.
Published: October 2005

A novel four-sided flextensional transducer has been constructed and tested for low-frequency operation. The transducer is in the shape of an asteriod formed by four curved concave metal plates driven at their junctions by four piezoelectric ceramic stacks configured as the spokes of a wheel. As the stacks expand in the positive cycle of operation, the four curved plates of the asteroid move outward in a motion that is the sum of the radial motion and the outward bending of the curved plates yielding a cumulative acoustic output. The experimental model tested is approximately 25 in. (0.635 m) in diameter and 6 in. (0.152 m) high with four curved steel plates, 0.25 in. (0.00635 m) thick, and operates in the frequency band from 500–1500 Hz. The results from the measurements show that current theoretical models for the conventional Class IV flextensional transducer may be used to estimate the performance of this transducer.
Sounds of swallowing
Authors: Hamlet Sandra , Nelson Richard , Patterson Robin
Published: October 2005

Sounds of swallowing as detected by a throat microphone have been used in the past primarily to mark the occurrence of swallowing. The source of these sounds and what information the signals might contain about function is relatively unknown. For this investigation, signals from a miniature accelerometer taped to the throat were recorded simultaneously with videofluoroscopic data taken while normal subjects swallowed small amounts of liquid barium suspension and barium paste. The progress of the barium “bolus” could thus be followed radiographically, and physical events in swallowing related in time to accelerometer signal characteristics. The most prominent signal feature is a relatively brief (200-ms) broadband noise that corresponds to the rapid passage of the bolus through the lower pharynx and cricopharyngeal sphincter into the esophagus. The spectrum of the noise contains stronger high-frequency components for a liquid than for a paste swallow. In close temporal proximity to this noise component, or even mixed with it, is often a periodic signal that is in the frequency range of high-pitched pronation (approximately 500 Hz) and which may be of laryngeal origin. Other low-amplitude signal features corresponded to structural movement of the hyoid/larynx or epiglottis. [Work supported by NIH.]
Measurement of flow excitation function
Authors: Sherman Charles H. , Ko Sung H. , Buehler Barry G.
Published: October 2005

Wave vector filter measurements have been made with the objective of improving quantitative knowledge of the flow excitation function. Two hydrophone arrays with the same number of elements but different spacings were used. The more closely spaced array covers high wavenumbers characteristic of the convective region of the turbulent boundary layer pressure fluctuations, while the other array covers the lower wavenumber region where contaminants associated with the experimental arrangement also usually exist. The arrays were mounted on a damped composite plate and tested at various flow speeds. Individual hydrophone outputs from both arrays were sampled simultaneously, digitized, recorded, and spectral analyzed in frequency and two wave vector components. Results will be presented as amplitude contour plots as a function of the two wave vector components on the plane of the plate at various frequencies. Results from the closely spaced array show the shape and level of the convective ridge and give an estimate of the difference between the convective peak level and the low wavenumber domain. Results from the other array show that the low wavenumber domain also contains wave vector components associated with free plate vibrations {confirmed by calculations based on work by D. J. Mead and S. Markus [J. Sound Vib. 10 (2) (1969)]} as well as acoustic components. [Work supported by ONR.]
Plates with regular stiffening in acoustic media: Vibration and radiation
Authors: Mead Denys J.
Published: October 2005

Flat plates and cylindrical shells with identical stiffeners at regular intervals constitute spatially periodic structures, and specially convenient methods of analysis are available for the study of their vibrations. Some of the methods are suitable for the inclusion of the effects of fluid loading from adjacent acoustic media. This paper outlines the nature of the free wave motion that can occur in periodic structures that are stiffened either in one direction or in two orthogonal directions. It is shown how their responses to distributed sound fields can be determined by using displacement functions consisting of a series of space harmonics or of simple assumed polynomial modes. The sound that is reradiated or transmitted by the structure is also found. Methods that have been developed for analyzing the response and radiation due to line or point forces are reviewed. Recent developments in the analysis of periodically stiffened cylindrical shells are described. The hierarchical finite element method has been applied to determine flexural wave speeds in both flat reinforced plates and in reinforced cylinders. Symbolic computing has been used to set up the relevant stiffness and mass matrices. Some computed results are presented.
Resonances in the sonar cross sections of shells near the sea surface
Authors: Gaunaurd G. C. , Werby M. F.
Published: October 2005

A model for the study of acoustic scattering from a spheroidal elastic shell located near a pressure-release interface has been developed. The model rests on the method of images and on the extended boundary condition (EBC) approach. The method yields a T matrix that maps the incident field onto the resulting scattered field. The approach is used to describe, compute, and display the echoes backscattered from the shell, as functions of frequency [i.e., the sonar cross section (SCS) of the target] and of angle [i.e., the differential scattering cross section (DSCS)], and it permits the determination of scattering patterns in the appropriate resonance frequency regime. A goal of the work is to assess the influence of a nearby pressure-release boundary on the location of the resonance features in the SCS of submerged elastic shells. The model predictions are illustrated with a variety of pertinent numerical displays exhibiting the resonance changes with increasing shell depths. The results are compared to simpler cases available elsewhere [i.e., IEEE J. Ocean. Eng. OE-12 (special issue on Scattering), 380–394, 395–403, and 419–422 (1987)].
Noise radiation from transverse air flow over cylinders of constant and varying diameter: Experimental investigation of parameters
Authors: Herdman Karen C. , Donavan Paul R.
Published: October 2005

Aeolian tones from nonrigid, circular cylinders fixed on one end were measured using sound intensity techniques. For cylinder diameters of the order of 3 to 4 mm and lengths of 750 mm, sound intensity was measured 18 in. from the cylinder axis at a direction perpendicular to the air flow. The radiated sound intensity and Strouhal numbers were determined for several cylinder diameters and flow velocities for the Reynolds number range of 4000 to 11 000. The sound intensity increased at a rate greater than theoretical velocity to the sixth power relationship [N. Curle, Proc. R. Soc. London Ser. A 231, 505–514 (1955)]. The influence of resonant vibration on the radiated sound is examined and compared to previous results [Leehey and Hanson, J. Sound Vib. 13, 465–483 (1971)]. Significant reduction in Aeolian tones with minimal axial taper was demonstrated.
Interaction effects of nasality and speaking fundamental frequency
Authors: Henton Caroline G.
Published: October 2005

Previous studies of nasality have concentrated on productional, acoustic, and perceptual features distinguishing nasal segments. Research reported here examines a wider aspect of nasality, namely its interaction with speaking fundamental frequency. To investigate whether nasality lowers or raises SFF, bilingual speakers recorded four passages that differed (a) as to language—French versus English—and (b) as to proportions of nasal segments. Speakers' SFF was measured in the four conditions. Statistical analysis of the results indicates that there is significant interaction of nasality with SFF, with sex of speaker and native language also being important variables. Implications of these results include: first, segmental interaction with prosodic elements; second, in speech synthesis, parameters for nasal segments and F0 may need to be interdependent, or variable, according to speaker sex or language spoken.
Prosodic characteristics and their control in Japanese speech under varying speaking styles
Authors: Miyatake Masanori , Sagisaka Yoshinori
Published: October 2005

Two sets of Japanese speech samples were analyzed to clarify the effects of speaking styles on prosodic parameters. The first set of 4068 isolated word utterances consists of 308 different Japanese words uttered in seven different ways, i.e., normal, slow, fast, strong, weak, high, and low. The second set of 110 conversational utterances consists of 11 different Japanese sentences uttered in four different conversational styles, i.e., normal, tender, restless, and irritated, and in one normal reading style. These samples were uttered by two professional narrators and their prosodic parameters [fundamental frequency (F0), power and segmental duration] were compared. The following tendencies were found from the analysis: (1) For most ordinary speaking styles (all but “high”) F0 and power are varied together. Correlations of 0.81∼0.99 were measured in these cases. (2) F0 can, however, be controlled independent of power, when subjects were instructed to do so (e.g., speaking style: high). (3) The average values and the dynamic ranges of F0 patterns differ between speaking styles. To realize these tendencies for speech synthesis by rule, a F0 control model is proposed. Applying analysis by synthesis to all samples in the first set at a time, the system parameters of this model could be derived. It is confirmed that the F0 pattern can be systematically generated by the proposed model for various speaking styles.
Acoustic characteristics of tongue root position and vowel assimilation in Akan
Authors: Munro Susan Hess
Published: October 2005

The purpose of this research was twofold: (1) To find an acoustic measure (or diagnosis) of tongue root position in a language where a difference of tongue root position is systematic and significant, and (2) apply this measure to cases of vowel assimilation between vowels of conflicting tongue root positions in order to determine whether tongue root positions were affected. Akan, a K wa language spoken in Ghana, exhibits a form of vowel harmony controlled by the tongue root in which the vowels in a particular word must be spoken with either an advanced or a retracted tongue root. The position of the tongue root [i.e., either advanced or retracted; hereafter referred to as either + or − ATR (advanced tongue root)] is determined by the word stem, and all affixes must agree with that tongue root position. In this paper, we will look at data from Kwawu, an Akan dialect, which has the following vowels: [i,e,u,o] are [+ ATR] vowels, while [ᶅ,ɛ,o,ɔ,a] are [− ATR] vowels. All [− ATR] vowels have variants when they occur in a syllable that precedes another word containing the high [+ ATR] vowels [i,u]. Two claims have been made about these variants. One asserts that the variants assimilate in tongue root position to the following [+ ATR] vowel and become [+ ATR] vowels themselves, while the other argues that the assimilation does not involve the tongue root but merely raising of the tongue blade. Resolving this dispute required that we first define a measure that would provide a reliable diagnosis of tongue root position. Only acoustic measures were considered as other means were not practical. Five kinds of measures were examined: formant frequency, formant bandwidth, duration, pitch, and amplitude of the first three harmonics. It was found that frequency bandwidth (more precisely the bandwidth of the first formant) provided the only reliable diagnosis of vowel type. The [+ ATR] vowels were found to have a greatly narrower first formant when compared with [− ATR] vowels. This measure was then used to examine the behavior of one of the [− ATR] vowels, the mid vowel [ɛ], in two contexts: before the high [+ ATR] vowels [i,u], and before the low [− ATR] vowel [a]. Bandwidth measurements of ɛ before the [+ ATR] vowels [i,u] do not show the narrower bandwidth found in [+ ATR] vowels, allowing us to preliminarily conclude that tongue root position is not assimilated.