bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of a method of simulating reduced frequency selectivity
Authors: Moore Brian C. J. , Glasberg Brian R. , Simpson Andrew
Published: October 2005

The accuracy of a method of simulating reduced frequency selectivity by the spectral smearing of complex stimuli has been evaluated. First an excitation pattern that would be evoked by a given nonsmeared stimulus in an impaired ear with broad auditory filters was estimated. Then the spectral smearing of the stimulus that would be necessary to create the same excitation pattern in a normal ear was calculated. The smearing was based on the shapes of simulated broad auditory filters; both symmetric and asymmetric broad filters were simulated. The method was used to process notched noise, and tones in notched noise, and the processed stimuli were used in a series of experiments with normally hearing subjects measuring the threshold for the tone in notched noise. The resulting data were used to derive auditory filter shapes. The derived filter shapes were generally similar to the expected shapes (based on the type of spectral smearing used), but there were some systematic discrepancies and some individual differences. The discrepancies do not seem to be due to the use of information derived from phase locking, since they were observed both at 1 kHz (where phase locking occurs) and at 6 kHz (where phase locking probably does not occur). The discrepancies also do not seem to be due to the transmission characteristics of the outer/middle ear, since they occurred both when these characteristics were taken into account in the fitting procedure, and when the stimuli were preshaped to compensate for these characteristics. The influence of the subjects’ own auditory filters probably can explain some of the discrepancies; the excitation pattern evoked by the spectrally smeared stimuli can be significantly influenced by the subjects’ own filters when those filters are not much sharper than the simulated filters used to produce the smeared stimuli. Finally, some of the discrepancies can probably be explained by subjects combining information across auditory filters, rather than just using the single ‘‘best’’ filter in each condition; this represents a limitation of the fitting procedure rather than of the simulation itself. Overall, the simulation worked reasonably well, especially when the smearing was based on symmetric filters.
Formant frequency discrimination by Japanese macaques (M
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Authors: Sommers Mitchell S. , Moody David B. , Prosen Cynthia A. , Stebbins William C.
Published: October 2005

These studies investigated formant frequency discrimination by Japanese macaques (Macaca fuscata) using an AX discrimination procedure and techniques of operant conditioning. Nonhuman subjects were significantly more sensitive to increments in the center frequency of either the first (F1) or second (F2) formant of single-formant complexes than to corresponding pure-tone frequency shifts. Furthermore, difference limens (DLs) for multiformant signals were not significantly different than those for single-formant stimuli. These results suggest that Japanese monkeys process formant and pure-tone frequency increments differentially and that the same mechanisms mediate formant frequency discrimination in single-formant and vowel-like complexes. The importance of two of the cues available to mediate formant frequency discrimination, changes in the phase and the amplitude spectra of the signals, was investigated by independently manipulating these two parameters. Results of the studies indicated that phase cues were not a significant feature of formant frequency discrimination by Japanese macaques. Rather, subjects attended to relative level changes in harmonics within a narrow frequency range near F1 and F2 to detect formant frequency increments. These findings are compared to human formant discrimination data and suggest that both species rely on detecting alterations in spectral shape to discriminate formant frequency shifts. Implications of the results for animal models of speech perception are discussed.
The dynamics of dynamics: A model of musical expression
Authors: McAngus Todd Neil P.
Published: October 2005

A computational model of musical dynamics is proposed that complements an earlier model of expressive timing. The model, implemented in the artificial intelligence language LISP, is based on the observation that a musical phrase is often indicated by a crescendo/decrescendo shape. The functional form of this shape is derived by making two main assumptions. First, that musical dynamics and tempo are coupled, that is, ‘‘the faster the louder, the slower the softer.’’ This tempo/dynamics coupling, it is suggested, may be a characteristic of some classical and romantic styles perhaps exemplified by performances of Chopin. Second, that the tempo change is governed by analogy to physical movement. The allusion of musical expression to physical motion is further extended by the introduction of the concepts of energy and mass. The utility of the model, in addition to giving an insight into the nature of musical expression, is that it provides a basis for a method of performance style analysis.
Reduction of tympanic membrane displacement during vocalization of the arboreal frog, Eleutherodactylus coqui
Authors: Narins Peter M.
Published: October 2005

Tympanic membrane (TM) velocities of vocalizing male frogs, Eleutherodactylus coqui, were measured in the field using laser vibrometry. The animal’s call produced levels of 114–120 dB SPL measured at distances of 12–20 mm from the eardrum and mean TM displacements in response to the two notes of the male’s own advertisement call were 1.84 and 2.08 nm, respectively. These values are close to the TM displacements obtained in response to playback of the two-note call at much lower sound levels. Thus TM vibrations are attenuated during phonation in the frog, and several candidate mechanisms for auditory sensitivity reduction are discussed.
Separation devices based on forced coincidence response of fluid-filled pipes
Authors: Tolt Thomas L. , Feke Donald L.
Published: October 2005

A separation process based on the acoustic radiation force created in stationary fields produced by a forced coincidence excitation at ultrasonic frequencies of fluid-filled pipes has been developed. The efficacy of this method for the collection and manipulation of fine secondary phases in flowing suspensions will be compared to equivalent operations in stationary fields generated in acoustic interferometer chambers operated without coincidence effects. The basis for the axial translation of the phases concentrated at the pressure nodes to either end of the cell as a result of an applied periodic sweep in the driving frequency will be examined.
Volume scattering in a shallow channel
Authors: Beran Mark J. , Frankenthal Shimshon
Published: October 2005

Using a generalization of the modal coherence equations previously developed by Sutton and McCoy [J. Math. Phys. 18, 1052 (1977)], the effect of volume scattering in a shallow channel is treated. The difference between the range behavior of the cross-modal coherence functions and the previously studied self-modal coherence functions is shown. In particular, calculations are made to evaluate the characteristic scales that govern the range decay of the cross-modal coherence functions. A particular example is given to illustrate the effect of the choice of different parameters.
Ocean acoustics turbulence study: Acoustic scattering from a buoyant axisymmetric plume
Authors: Goodman L. , Oeschger J. , Szargowicz D.
Published: October 2005

Limited in situ measurements from high-frequency underwater acoustic echosounders have suggested that there may be circumstances in which acoustic scattering from ocean temperature variability is sufficiently intense to be observable over volume reverberation due to biologics. A new laboratory program, the ocean acoustics turbulence study (OATS), has been undertaken to quantify such scattering. The laboratory employs a very precise computer-controlled positioning system and allows a scattering geometry from a near forward-scattering angle, 5°, to a near backscattering angle, 160°. This article reports on results of an initial set of experiments utilizing a 1-MHz, 1-cycle transmitted pulse scattering from a temperature anomaly field produced by a laminar buoyant plume. The objective of this experiment is to compare observations of acoustic scattering from the temperature anomaly with that predicted by the Bragg scattering condition. A parameter regime is chosen such that the laminar plume has an approximately axisymmetric and Gaussian temperature profile. For the two-dimensional axisymmetric case, the Bragg scattering condition allows prediction of an acoustically derived two-dimensional Fourier transform of the temperature field. The acoustically derived two-dimensional Fourier transform and the one derived directly from in situ temperature measurements are in good agreement, except at the higher frequency range of the bandwidth of the scattered signal. Discussion of the possibility of inverting such measurements for a direct calculation of the temperature field is presented.
Narrow-band performance of phase-conjugate arrays in dynamic random media
Authors: Dowling David R. , Jackson Darrell R.
Published: October 2005

The theoretical narrow-band performance of acoustic phase-conjugate arrays in the presence of static and dynamic random media is presented. For a static random medium, analytical formulas are derived for the mean focus field of a Gaussian-shaded volumetric phase-conjugate array. The results suggest that random refraction allows phase-conjugate arrays to ‘‘super focus,’’ that is, produce a focal region smaller than the free-space diffraction limit. More specifically, vertical phase-conjugate arrays are predicted to have horizontal directivity. In a dynamic random medium, phase-conjugate array performance is degraded by changes in the medium that occur between the time that the acoustic signal is launched from its source and the time that the array’s transmission is received back at the source location (the round-trip time delay). Formal results are obtained for an intrinsic signal-to-noise ratio for the signal sent from the phase-conjugate array based on a combination of multiple scattering from static random refraction and single scattering from dynamic random refraction in the acoustic medium. These formal results are reduced to analytical formulas for a random medium characterized by the statistics of oceanic internal waves. The intrinsic signal-to-noise ratio is found to be proportional to: the inverse square of the round-trip time delay, the inverse square of the acoustic frequency, the inverse first power of the array-source range, and a simple function that combines the size of the array and the parameters of the random medium. For a typical deep-water oceanic medium at acoustic frequencies near 10 kHz, phase-conjugate array performance may be unaffected for round-trip time delays as long as a minute.
Phonation threshold pressure: A missing link in glottal aerodynamics
Authors: Titze Ingo R.
Published: October 2005

Phonation threshold pressure has previously been defined as the minimum lung pressure required to initiate phonation. By modeling the dependence of this pressure on fundamental frequency, it is shown that relatively simple aerodynamic relations for time-varying flow in the glottis are obtained. Lung pressure and peak glottal flow are nearly linearly related, but not proportional. For this reason, traditional power law relations between vocal power and lung pressure may not hold. Glottal impendance for time-varying flow should be defined differentially rather than as a simple ratio between lung pressure and peak flow. It is shown that the peak flow, the peak flow derivative, the open quotient, and the speed quotient of inverse-filtered glottal flow waveforms all depend explicitly on phonation threshold pressure. Data from singers are compared with those from nonsingers. The primary difference is that singers obtain two to three times greater peak flow for a given lung pressure, suggesting that they adjust their glottal or vocal tract impedance for optimal flow transfer between the source and the resonantor.
Identification of human myocardial infarction i
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Authors: Wickline Samuel A. , Verdonk Edward D. , Sobel Burton E. , Miller James G.
Published: October 2005

It has been reported previously that acute and mature myocardial infarction in dogs can be differentiated in vitro and in vivo by ultrasonic tissue characterization based on measurement of the frequency dependence of ultrasonic backscatter. To characterize human infarction with an index of the frequency dependence of backscatter that could be obtained in patients, cylindrical biopsy specimens from 7 normal regions and 12 regions of infarction of 6 fixed, explanted human hearts in 2-deg steps around their entire circumference with a 5-MHz broadband transducer were insonified. One to six consecutive transmural levels were studied for each specimen. The dependence of apparent (uncompensated for attenuation or beam width) backscatter, ‖B(f)‖2, on frequency (f) was computed from spectral analyses of radio-frequency data as ‖B(f)‖2=afn, where from theoretical considerations the magnitude of n decreases as scatterer size increases. Apparent integrated backscatter was computed as the average of ‖B(f)‖2 from 3 to 7 MHz. The average value for n for normal tissue (0.9±0.1) exceeded that for tissue from regions of infarction (0.6±0.1; p<0.05). Infarct manifested a significant decrease of n from epicardial to endocardial levels (epi→mid→endo: 0.9→0.7→0.2; p<0.05) whereas normal tissue manifested similar values for n at each transmural level (0.8→1.1→0.9; p=NS). Average integrated backscatter across all transmural levels for infarct was significantly greater than that for normal tissue (−48.3±0.5 vs −53.4±0.4 dB, infarct versus normal; p<0.05). The presence of fibrosis was associated with smaller values of n and greater integrated backscatter. Thus human myocardial tissue from areas of infarction can be differentiated from normal tissue based on its frequency dependence of apparent backscatter and on the magnitude of frequency-averaged, or integrated, backscatter.
Piezoelectric ceramic compositional development
Authors: Berlincourt Don
Published: October 2005

The original piezoelectric ceramic material was unmodified barium titanate. It was little used except as compositionally modified. The earliest work was by W. P. Mason and this led to improved characteristics for sonar transducers and then to phonograph cartridge applications. By the mid 1950s, lead zirconate titanate (PZT) materials were shown by B. Jaffe to have higher piezoelectric coupling and application at much higher temperatures. Over the next 10 years, many modified compositions were developed. These led to much improved sonar systems and ultrasonic cleaners and to applications in ultrasonic bonders, stereo phonograph cartridges, and even printers. The new compositions also made possible applications such as piezoelectric ceramic filters, gas ignition devices, and camera flashbulb actuators. More recently, specialized ceramics have been developed based on lead titanate and lead metaniobate, but major efforts have been directed to applications of lead titanate zirconate compositions, which now touch virtually every home and automobile. The history of compositional studies with ferroelectric ceramics is reviewed and the types of characteristics achieved are summarized. The compositional additives and some general principles to explain their behavior are discussed.
Directional characteristics of underwater acoustic helical antennas
Authors: Hasegawa Akio , Kikuchi Toshiaki
Published: October 2005

An underwater acoustic helical antenna is constructed through the acoustic analog of the axial-mode helical antenna typically for electromagnetic application. The acoustic antenna consists of two elements: a cylindrical helix made of a brass rod and a PZT Langevin transducer driver. This paper derives the design factors for an optimum helix geometry. The acoustic helical antenna acts as an underwater endfire antenna over broad frequency ranges, but can be characterized by the large magnitude of its side lobes. Next, an equiangular spiral antenna is described that has reduced side lobes. The experimental results for the test helices are in relatively good agreement with the calculated results.
The acoustic sound field above a porous layer and the estimation of the acoustic surface impedance from free-field measurements
Authors: Allard Jean-François , Lauriks Walter , Verhaegen Christine
Published: October 2005

An exact evaluation of the acoustic field created by a point source in a semi-infinite fluid above a layer of another fluid of finite thickness is worked out. A method of measuring the characteristic impedance and the propagation constant in a layer by a two-microphone technique is presented. An example is given where the semi-infinite fluid is air and the layer is a fluid equivalent to a porous material.
Corrected values for Annex B of ISO 1999
Authors: Clark William W. , Bohl Carl D.
Published: October 2005

A recalculation of the values contained in Annex B of the new ISO standard R1999: ‘‘Determination of occupational noise exposure and the estimation of noise-induced hearing impairment,’’ utilizing procedures specified in the standard and in its supporting documentation was conducted. Three calculation errors, which occurred in the supporting document and were perseverated into the standard, were identified. These errors are explained and a corrected version of Annex B is presented.
Modal analysis of Kelvin viscoelastic solids under arbitrary excitation: Circular plates under moving loads
Authors: Shen I. Y. , Mote C. D.
Published: October 2005

The response of a finite, inhomogeneous, Kelvin viscoelastic solid under arbitrary excitation is determined by modal analysis. Through the reciprocal theorem of viscoelasticity, vibration modes of the Kelvin viscoelastic solid satisfy orthogonality conditions and the system response under any excitation is represented in a modal series. This formulation technique is illustrated on an asymmetric, classical, circular plate containing Kelvin inclusions excited by a constant transverse force rotating at constant speed. The viscosity of the inclusions suppresses the instability excited at supercritical speed in the elastic plate, but it may or may not suppress instability excited at subcritical speed depending on the geometry and location of the Kelvin inclusions.
Enhancement of the compound action potential: Effects of adaptation and unmasking
Authors: Henry Kenneth R.
Published: October 2005

Although forward masking typically results in amplitude reduction of the compound action potential (CAP) produced by a probe stimulus, enhancement of CAP amplitude can occur within two restricted frequency-intensity domains of a forward masker. Enhancement boundaries are as robust as those of the CAP tuning curve (TC) to changes of probe stimulus repetition rates from 3.33 to 10 Hz. Amplitudes of CAPs, in response to probe stimuli presented at a 2-Hz repetition rate, are larger than those obtained at a 10-Hz repetition rate. This is apparently because, in the absence of a forward masker, each probe stimulus is forward masked by the preceeding probe stimulus. The enhancement ratio (the amplitude of the forward-masked CAP divided by that of the unmasked CAP) is greater with probe repetition rates of 10 than of 2 Hz. Lengthening the probe stimulus duration increases both adaptation and the enhancement ratio. The low-frequency enhancement domain overlaps with one of the two-tone unmasking regions which reflects two-tone suppression (2TS). However, 2TS and enhancement differ in their effects at central and high masker frequency regions.
Auditory intensity perception: Successive versus simultaneous, across-channel discriminations
Authors: Dai Huanping , Green David M.
Published: October 2005

This study measures the ability of observers to compare the intensities of two stimuli occupying different frequency regions. It includes three experiments, each experiment having two conditions. In one condition, the two stimuli to be compared were presented simultaneously within each interval; this condition has been called profile analysis. In the other condition, the two stimuli were presented successively within each interval. Because the overall level of the stimuli was randomized between intervals, the observers were encouraged to compare the intensities of the two stimuli within each observation interval rather than between intervals. The stimuli were two simple tones in experiment 1 and two tonal complexes in both experiments 2 and 3. The stimuli used in experiments 2 and 3 differed in frequency. The results show that simultaneous comparisons are superior to successive comparisons. For simple tones, the difference in threshold is about 8 dB; for complexes with 10 to 11 components, the difference in threshold is about 15 dB. These differences can be explained by assuming that internal noises in different channels were partially correlated when stimuli in those channels were presented simultaneously and were independent when the stimuli were presented successively. Cancellation of the correlated noise is therefore possible with simultaneous comparisons, making such discrimination better than that achievable with successive comparisons.
Experimental detection of a slow acoustic wave in sediment at shallow grazing angles
Authors: Boyle Frank A. , Chotiros N. P.
Published: October 2005

Following recent experimental results at sea [N. P. Chotiros, Proceedings of Oceans ’89] that suggest the existence of a previously undetected type of acoustic wave in sandy sediments, an experiment was designed to detect and measure the speed of acoustic waves in an isolated environment. The experiment was conducted in a laboratory tank containing 1 m of unwashed river sediment under a 3-m water column. Observations were made of the travel time and attenuation of a pulse from an acoustic source located above the water–sediment interface to a set of probes below the interface. It was observed that, at normal incidence the pulse traveled at about 1675 m/s, while at shallow grazing angles, the pulse traveled through the sediment at close to 1200 m/s. An interesting possible explanation exists in the Biot theory for acoustic propagation through fluid-saturated porous media, which predicts a slow acoustic wave in porous materials.
Functional organization of velar movements following jaw perturbation.
Authors: Kollia H. Betty , Gracco Vincent L. , Harris Katherine S.
Published: October 2005

Mechanical perturbation of the articulators has been used to examine motor control principles underlying speech production. One common observation is that if one member of a group of functionally related articulators is perturbed during articulation, the other members compensate. The compensatory response patterns reflect sensorimotor organization for speech, and thus have implications for speech production theories. The present experiment examines such linkages by analyzing the spatiotemporal response patterns to jaw perturbation displayed by the anatomically linked and remote jaw, upper lip, lower lip, and velum. Subjects were fitted with a mandibular prosthesis to allow delivery of jaw-lowering, random (20% of the trials) perturbations during productions of the utterance /mabnab/. Lip, jaw, and velar kinematics were recorded optoelectronically and simultaneously with the acoustic signal. These movements exhibited compensatory actions including increased movement displacement and oral closing velocity. Movement duration changes were also observed. Coordinative timing among lips, jaw, and velum was generally maintained following the perturbation. Variations in that timing appear to depend on the temporal relations between the onset of the perturbation and the onset of the component speech event. [Work supported by NIH Grant Nos. DC-00121, and DC-00594 to Haskins Laboratories.]
Asymptotic and numerical determinations of the complex eigenfrequencies and the real resonances of an acoustically insonified sphere
Authors: Gaunaurd Guillermo C. , Wertman William H.
Published: October 2005

Various aspects of the scattering problem associated with the incidence of a plane sound wave on a sphere are studied. Various tables are numerically generated that exhibit the external eigenfrequencies of acoustically rigid, soft, and elastic spheres, as well as the related (electromagnetic) TM and TE modes of perfectly conducting spheres. Also generated are tables of the (complex) ‘‘composition’’ zeros of an elastic sphere in water and they are compared to the (real) physical natural resonances of this target. Some of these tables cover new expanded frequency ranges, and in some instances either correct some of our previous misprints/typos or are totally novel. An acoustical analog of the Bohr–Sommerfeld quantization rule of (the old) quantum theory is used to asymptotically evaluate the external eigenfrequencies of the sphere. The resonance condition that emerges from this phase-matching principle is identical to the asymptotic expansion for the (complex) zeros of the spherical Hankel functions found by Olver in the fifties. This yields an asymptotic determination of the external eigenfrequencies of a sphere. This paper concludes with a study of the asymptotic spacings between consecutive shape-dependent zeros of the sphere, where a uniform value for one of these spacings is obtained (i.e., the one that results when the index n is kept fixed), which agrees with earlier numerical calculations of ‘‘background’’ curves. The zeros in these tables, which are analyzed here, are essential for the characterization of scatterers and for the solution of target identification problems. They are also indispensable for the determination of the dispersion plots for the phase (and group) velocities and attenuations of the surface waves that revolve around scatterers of any shape, and all these applications are described.
Study of acoustic resonance in enclosures using eigenanalysis based on boundary element methods
Authors: Bai Mingsian R.
Published: October 2005

It is well known that, from the modal theory of room acoustics, resonance will occur if the driving frequency of a sound source located in a room coincides with one of the natural frequencies of the sound field. In this study, an eigenanalysis technique based on the boundary element method (BEM) is developed for extracting eigenmodes of a sound field in an enclosure. A method of singular value search, in conjunction with a golden section optimization algorithm, is utilized for efficient calculation of eigenmodes. In particular, modes associated with repeated eigenvalues can be well resolved by the technique developed in this research. Enclosures of various geometries have been analyzed by using the developed algorithm in a numerical simulation. Satisfactory agreement has been achieved between the BEM results, the FEM results, and the analytical solutions if available.
A signal detection theory analysis of phoneme boundary shifts.
Authors: Fahey Richard
Published: October 2005

Phoneme boundary shifts are well documented in the speech perception literature. Signal detection theory (SDT) models of speech perception allow for two possible explanations for these. Boundary shifts may be due to criterion shifts at a decision level or to changes in the underlying representations of stimuli. SDT methods can be applied to both identification and fixed-level discrimination data. While not providing a definitive explanation of a phoneme boundary shift, the results of such analyses can constrain explanations. In the present investigation, SDT analyses were applied to both identification and fixed-level discrimination results in which phoneme boundary shifts were observed. These data come from two sets of studies: (1) a ‘‘rate normalization’’ experiment, in which the duration of syllables affected voicing judgments, and (2) a trading relations study, in which the medial fricative/affricate boundary was influenced by both the silent duration before the fricative noise and fricative rise time. Implications for existing explanations of both of these phoneme boundary shifts are discussed. [Work supported by NIH.]
An ultrasonic spike pulse emission circuit.
Authors: Wei Jingsheng
Published: October 2005

For many ultrasonic testing instruments, the piezoelectric transducers are working under a pulse situation. To improve the resolution of these instruments, the designs of the transducers must be considered. Recently, some ultrasonic instruments such as blood flow instruments, a Doppler system that uses ultrasonic pulsed random signals, and spectral analysis in food ultrasonography all emit and receive wideband spike pulses, so that they need piezoelectric transducers and emission circuits with a wider frequency band and higher efficiency. In this paper use is made of a Redwood equivalent circuit and a Laplace transform to analyze the impulse response of the emitting and receiving networks for the thickness mode piezoelectric transducers. The theoretical analysis shows that the sensitivity of the acoustic system is proportional to the square of the electromechanical coupling coefficient and inverse to the flight time of the ultrasonic wave within the transducer. An ultrasonic spike pulse emission circuit for thickness mode piezoelectric transducers was installed on the basis of theoretical analysis. The experimental results are in good agreement with the theoretical results.
Axisymmetric wave propagation in fluid-loaded cylindrical shells: Theory versus experiment.
Authors: Plona Thomas J. , Sinha Bikash K. , Kostek Sergio , Chang Shu-Kong
Published: October 2005

This paper discusses both theoretical and experimental aspects of axisymmetric wave propagation along fluid-loaded cylindrical shells (excluding torsional modes). For a steel cylindrical shell with a fixed ratio of inner to outer radius, four different fluid configurations are considered: water inside and outside the steel shell; air inside and outside; water inside and air outside; and air inside and water outside. Calculations of the transient pressure response for the case of an axisymmetric ring source and a point receiver are made as a function of source–receiver separation. Experimentally, a PZT ring source and ring receiver are placed around a steel cylindrical shell with an outer radius of 9.53 mm and an inner radius of 7.94 mm. Waveforms are recorded for multiple source–receiver hydrophone spacings in the frequency band 50–240 kHz. Using a Prony’s method, the complex wave number as a function of frequency for each of the modes in the system is derived from both the theoretical and experimental waveforms. These axisymmetric modes are grouped into three categories: steel modes, non-cutoff fluid modes, and cutoff fluid modes. Excellent agreement is obtained between theory and experiment.
Comparisons of monkey and human sensitivity to speech, nonspeech, and monkey speech sounds.
Authors: Sinnott Joan M.
Published: October 2005

Psychoacoustic studies are reviewed comparing monkey and human differential sensitivity to a wide variety of simple and complex auditory signals. (1) Nonspeech: for the basic psychoacoustic capacities of pure tone frequency (ΔF), intensity (ΔI), and temporal (ΔT) discrimination, monkeys discriminate +ΔI nearly as well as humans, but are moderately less sensitive to ΔT, and markedly less sensitive to ΔF and −ΔI. (2) Speech: Monkeys show varying degrees of sensitivity to complex human speech sounds. Monkeys are as sensitive as humans to English liquid /ra–la/ contrasts, moderately less sensitive to English VOT /ba–pa/, place of articulation /ba–da/, stop-glide /ba–wa/, and various vowel contrasts, but markedly less sensitive to prevoiced Spanish VOT contrasts. (3) Monkey-speech: Monkeys are moderately less sensitive than humans to temporal variation in pitch peak position along a macaque coo continuum. Taken together, all these data indicate a good correspondence between monkey sensitivity to ΔI and ΔT in simple and complex sounds. However, this is not the case for ΔF, since monkeys appear more similar to humans in discriminating spectral variation in complex sounds than in simple pure tones. [Work supported by NIDCD.]
Dynamic behavior of a piezoelectric dry femur.
Authors: Dökmeci M. Cengiz
Published: October 2005

This paper is concerned with a mathematical model for the dynamic behavior of a piezoelectric dry femur. The dry femur is taken as a cylindrical bar of approximately circular cross section. The mechanical displacements and the electric potential of the dry femur are expanded in a series of Jacobi polynomials in terms of the polar coordinates of the cross section. These expansions are inserted into a generalized variational principle [M. C. Dökmeci, IEEE Trans. Ultrason. Ferroelec. Freq. Control 35(6), 775–787 (1988)] so as to consistently deduce a hierarchy of one-dimensional equations of the dry femur from the three-dimensional equations of piezoelectricity. These macroscopic equations, which are expressed in both variational and differential forms, accommodate all the extensional, radial, flexural, and torsional motions as well as coupled motions of femur. The uniqueness of solutions in the governing equations of femur is investigated and the initial-mixed boundary conditions are enumerated which are sufficient for the uniqueness. Cases involving special motions are considered, some conclusions regarding the results obtained are drawn, and future needs of research are indicated. [Work supported in part by the U.S. Army through its European Research Office.]
Seafloor shear wave velocity variability.
Authors: Dorman LeRoy M.
Published: October 2005

In gross classification, sediments of the deep seafloor may be of terrigenous or marine origin. Those of marine origin are classified as oozes (generally calcareous) or clays (generally siliceous) depending largely on whether their CaCO3 content is greater or less than 30%. The carbonate contents is, in turn, controlled both by the biological productivity of the surface waters and the circulation patterns of the deep waters of the oceans. Older waters have more dissolved CO2 and attack carbonates more aggressively. There are now a few deep-sea in-situ shear velocity measurements in siliceous and calcareous sediments. The siliceous sediments show velocities that are the lowest, 20–30 m/s at the surface, while calcareous sediments have slightly higher velocities. Both of these have velocities lower than those found in shallow silts and sands. Measurements of the shallow shear velocities show high variability, approaching 50%, over a few km distance in the siliceous sediment (Dorman etal., 1991). These measurements are made using interface waves from seafloor explosions observed using ocean bottom seismographs. These may be correlated with the channeling of sediments but the mechanism is far from clear. [Work supported by ONR.]
Spatial variability of surficial shallow-water sediment geoacoustic properties.
Authors: Richardson Michael D.
Published: October 2005

In a previous publication [Richardson, in OceanSeismo-Acoustics (Plenum, New York, 1985), pp. 527–536] the author reviewed relationships between physical and biological processes and the resultant variability of values of sediment geoacoustic (compressional wave velocity and attenuation) and physical (grain size and porosity) properties. In this presentation the subject is revisited, using values of compressional and shear wave velocity measured insitu instead of the laboratory measurements considered in the previous paper.
Conversion of seismic waves in inhomogeneous and anisotropic sediments.
Authors: Schmidt H. , Fan H.
Published: October 2005

Traditionally theoretical and numerical modeling in ocean bottom seismo-acoustics has assumed the sediments to be horizontally stratified, allowing for integral transform or wave-number integration methods to be used, as for example the safari code [H. Schmidt and F. B. Jensen, J. Acoust. Soc. Am. 77, 813–825 (1985)]. Although this assumption is often valid, there is experimental evidence that such simplified environmental models are not always correctly representing the seismo-acoustic behavior. Thus the seasonal nature of the sedimentation process introduces a fine layering that is usually ignored. However, such a sediment will not be isotropic, even at low frequencies, but exhibit transversely isotropic behavior. Here use is made of a modified version of safari to demonstrate the effect of this anisotropy on the seismo-acoustics. Another, even more significant effect is introduced by lateral inhomogeneities giving rise to scattering as well as seismic wave type conversion. For example, horizontally polarized Love waves are often observed in experimental data, a feature that is not predicted by the simple two-dimensional theories. Here, a 3-D extension of an elastic boundary element code [P. Gerstoft and H. Schmidt, J. Acoust. Soc. Am. 89, 1629–1642 (1991)] is used to demonstrate how the excitation of the Love waves can be explained by the presence of such discrete, lateral inhomogeneities in the stratification.
Noise protection measures on military training facilities of the German Bundeswehr.
Authors: Heiwolt Gerhard
Published: October 2005

More than a decade ago it was believed that the same noise abatement measures that were established for traffic or industrial noise would also work for shooting noise in the vicinity of rifle ranges. In the early 80’s MoD Bonn began to study and to enhance new abatement facilities with respect to the special requirements for shooting noise. The studies apply to constructions, now regarded as ‘‘state of the art’’ so far as Germany is concerned. This report discusses the first constructions to reduce muzzle blast and projectile shock (sonic boom) by enclosing the ranges with sound absorbing ceilings and walls. Furthermore, special measures were developed to reduce sound reflection at structures on or near the ranges. A selected combination of such measures is now successful in protecting a residential area in a certain direction. Some examples of noise reduced shooting ranges in Germany are introduced including some remarks on how to use the structural principles on American-style training facilities in Germany. MoD will continue the support of investigations on noise abatement measures for small arms. There are still 40 military facilities in Germany that need noise abatement measures by law. The technical concept for the German Bundeswehr will be introduced.
Noise reduction using coffered ceiling models.
Authors: Bradley Wayne
Published: October 2005

A scale (1 ft=1 m) model of a German coffered ceiling [E. Buchta, ‘‘Noise Control Study of a Light and Air Permeable Coffered Ceiling at an MG-Range in Northeim,’’ Institute for Noise Control, Dusseldorf, Germany (1985)] and three variations were designed, built, and tested at CERL. To measure the efficiency of these ceilings, a scale representation of the spectral range for small arms fire was radiated through the suspended models. The noise reduction measured for these models is compared to theoretical design curves calculated by Cremer [L. Beranek, NoiseandVibrationControl (Inst. of Noise Control Eng., Washington, DC, 1988)] for attenuation in lined ducts. When the ceilings are considered to be arrays of short lined ducts, Cremer’s theory predicts the experimental noise reduction. Attenuation is found to be linearly dependent on the depth of the ceiling. In order to attenuate lower frequencies, the spacing between baffles must be increased. Therefore, size constraints will determine a lower bound on frequencies effectively attenuated by such ceilings.
Computer-based gun and blast noise monitoring systems and algorithms.
Authors: Snell A. M.
Published: October 2005

This paper describes the use of computer-based noise monitoring systems, the methods of data acquisition, and some new ideas on the analysis of the data for detection of gun noise blasts. The principles and methods are suitable for medium and large area installations. With many modern noise monitoring systems, large amounts of data are acquired for post-analysis. This suggests the use of computers and micro-based instruments to remove the tedium and to actually make the analysis possible. The principle involved in this type of system is to acquire raw data throughout the day (or any other suitable period) from a number of noise monitoring terminals around the site. These data are automatically transferred to the computer for analysis. There is nothing new about this. The difficulties arise in differentiating gun and blast noise generated at the site from, for example, a car door slamming nearby. Elaborate frequency correlating algorithms can be used. These may work but at the expense of complexity and, of course, cost. Everyone knows the saying that ‘‘The simple methods are always the best.’’ With this in mind, a detection method has been developed using a twin-channel instrument logging short Leq and peak. With one monitor close to the known source and others located around sensitive areas, algorithms have been produced and put into practice, which allow the reliable measurement of small, medium, and large arms around varying areas.
An analysis of low-frequency wind noise in turbulent environments.
Authors: Morgan Scott , Raspet Richard
Published: October 2005

Simultaneous measurement of wind noise and the instantaneous wind speed were performed for bare and screened microphones outdoors. Analysis of these measurements demonstrates that the dominant source of pressure fluctuations at the microphone outdoors is the intrinsic turbulence in the flow. This is in contrast to the results of measurements performed in low turbulence environments by Hosier and Donavan and by Strasberg. For low turbulence conditions the fluctuating wake of the screen is the dominant noise source. This finding has important implications for windscreen design for outdoor measurements since the principles described by Hosier and Donavan apply only to low turbulence conditions.
Wave scattering from a rough ground in an inhomogeneous medium.
Authors: Li Y. L. , Franke S. J.
Published: October 2005

An exact analytical expression of the Green’s function is obtained for the case of a time-harmonic linesource embedded in a medium with the linear sound-speed profile. This is the first time an analytical two-dimensional Green’s function has been found for wave propagation in an inhomogeneous medium. Substituting the exact analytical expression of the Green’s function into the Helmholtz–Kirchhoff integral equation and using the method of moments, the scattered fields from a ground with barriers or troughs in such a medium are computed. The effects of scattering in the region beyond the caustic surface are also studied. [Work supported by U.S. Army Construction Res. Lab.]
Propagation of pulsed finite amplitude sound beams in a liquid with strong absorption.
Authors: Averkiou Michalakis A. , Lee Yang-Sub , Hamilton Mark F.
Published: October 2005

Measurements of intense acoustic pulses generated by directive sources in a liquid with strong absorption are compared with theoretical predictions based on a time domain numerical solution of the KZK nonlinear parabolic wave equation [Lee and Hamilton, in UltrasonicsInternational 91 ConferenceProceedings (Butterworth–Heinemann, Oxford, 1991), pp. 177–180]. The computer program is useful for describing the propagation of tone bursts with various amplitude and frequency modulations. Experiments were performed in glycerin with narrow-band pulses having center frequencies of several megahertz. The pulses experience self-demodulation that leads to far-field waveforms characterized by the low-frequency envelope, as predicted by the asymptotic theory of Berktay [J. Sound Vib. 2, 435–461 (1965)]. Good agreement between theory and experiment was obtained for amplitude-modulated tone bursts, not only at far-field axial positions as achieved first by Moffett etal. [J. Acoust. Soc. Am. 49, 339–343 (1971)], but also off axis, throughout the transition region and into the near field. the effects of frequency modulation are also discussed. [Work supported by the ONR and the David and Lucile Packard Foundation.]
Observation of a new surface mode on fluid-saturated porous solids.
Authors: Nagy Peter B.
Published: October 2005

Almost 10 yr ago, Feng and Johnson predicted the presence of a new surface mode on a fluid/fluid-saturated porous solid interface [J. Acoust. Soc. Am. 74, 906 (1983)]. The most interesting feature of this new mode is that, as a true guided mode, its velocity is lower than any of the bulk velocities in the surrounding media, including the slow compressional wave. Experimental observation of this mode is rendered very difficult by the requirement that the pores at the surface be closed. It was found that, due to surface tension, practically closed-pore boundary conditions can prevail on the ‘‘free’’ surface of most fluid-saturated solids. Strong capillary forces at the boundary between the nonwetting (air) and the wetting (water or alcohol) fluids extend an ideally thin but very stiff membrane over the otherwise open-surface pores. The surface mode was directly excited by a vertically polarized shear transducer mounted at the edge of the sample and detected by a heterodyne laser interferometer. Surface wave velocity and attenuation measurements were made on both synthetic and natural porous solids in the frequency range between 50 and 300 kHz. The experimental results provide clear evidence of the new ‘‘slow’’ surface mode predicted by Feng and Johnson and show the feasibility of using this mode for characterization of permeable formations.
Scholte wave generation.
Authors: Duclos Jean , Tinel Alain
Published: October 2005

The Scholte–Stoneley interface wave is interesting in an acoustic field because it does not decay during its propagation. Different techniques have been used to generate this liquid/elastic solid interface wave. Some of these techniques are based on the conversion of an incident wave, for example a longitudinal wave in the case of the alcohol wedge method. A Scholte wave can be generated directly using an interdigital transducer (I.D.T.) deposited on a piezoelectric substrate, or an amorphous substrate covered with a thin piezoelectric film. The study of the reversibility of the Scholte wave diffraction phenomenon by a dihedral [A. Tinel and J. Duclos, Acoust. Lett. 15, 30–35] leads to the presentation of another technique to generate a Scholte wave. It has been verified that the interaction of an incident bulk wave with the dihedral in a particular direction results in a Scholte wave at the interface. This method is efficient and easy to use.
Experimental study of Scholte wave diffraction by a dihedral.
Authors: Tinel Alain , Duclos Jean
Published: October 2005

The theoretical study of waves capable of propagating at a liquid/elastic solid interface may lead to many solutions. Some of these solutions correspond to interface waves that are characterized by their direction of propagation parallel to the interface and by their possible reemission in the fluid medium. After recalling the main characteristics of the Scholte–Stoneley and the Rayleigh waves, the authors propose an experimental study of the diffraction of the Scholte wave by a dihedral edge. When the Scholte wave meets the dihedral perpendicularly, two phenomena occur. First, a phenomenon of pure diffraction characterized by a bulk wave mainly propagating in the interface direction. This is essentially due to the component of the Scholte wave in the liquid. Second, some conversions occur giving a reflected Scholte wave, a transmitted one, and two leaky Rayleigh waves. It is possible to prove reemission directions of the generalized Rayleigh waves in accordance with the solid nature and the dihedral angle.