bluuebunny/crossref_metadata_2025 huggingface dataset:
Perceptual features of speech for males in four perceived age decades
Authors: Hartman David E. , Danhauer Jeffrey L.
Published: October 2005

Spontaneous speech samples of 46 male speakers between the ages of 25 and 70 years were played to 40 untrained listeners who estimated the speakers’ ages. Samples which showed agreement among untrained listeners were played to 20 trained listeners who described the perceptual features of the given perceived ages via a closed-response schema. Results showed characteristic perceptual features for four perceived age decades which could be classified according to pitch, rate of speech, quality, and articulation. The features were discussed in light of earlier findings. The features and their weightings by the listeners were derived from an a posteriori schema and samples of spontaneous speech. It was concluded that these features have perceptual importance and should be useful in establishing criteria for defining ’’normal’’ aging speech, planning management strategies for individuals with speech deviances, and in speaker recognition research.

Subject Classification: [43]70.30, [43]70.35.
Dynamic response of a bounded, three-dimensional, viscoelastic body
Authors: Felszeghy Stephen F. , Sackman Jerome L. , Goldsmith Werner
Published: October 2005

The isothermal response of a bounded, three-dimensional viscoelastic body, subject to arbitrary body forces, initial conditions, and boundary conditions, is considered within the linear theory of viscoelasticity. The viscoelastic properties of the body are assumed to be isotropic and homogeneous. The boundary surface areas over which the boundary conditions are specified are assumed to remain constant with time. The response is first found formally in terms of a causal Green’s function. It is then shown that when Poisson’s ratio is constant, the causal Green’s function can be expanded in a series of spatial eigenfunctions of an associated elastic eigenvalue problem. The resulting solution for the general problem is an eigenfunction series with Laplace transformed time-dependent coefficients. The solution is inverted for two special cases, when the body forces and boundary conditions are separable in space and time, and when the relaxation function in simple shear has the form of a series of decaying exponentials.

Subject Classification: [43]40.20; [43]35.50.
Large wavelength pulse propagation in curved elastic rods
Authors: Moodie T. Bryant , Rogers C. , Clements D. L.
Published: October 2005

Longitudinal pulse propagation in slightly curved elastic rods is discussed in terms of an elementary theory due to Hsieh and Lee for which rotary inertia and radial shear are neglected. Moreover, the wavelength of motion is sufficiently long for practically all bending effects to be neglected. Three different approaches are presented. In the first, reduction of the Fourier transform of the governing equation to Bessel’s equation is sought. In the second, generalized Baecklund-type transformations are utilized to reduce the characterizing equation to the conventional wave equation for certain radius of curvature variations. Finally, the formal Karal–Keller technique is used to solve certain impact problems. Numerical results are presented in graphical form.

Subject Classification: [43]40.22; [43]20.15, [43]20.20, [43]20.45.
Diffuse sound fields: Eigenmode and free-wave models
Authors: Waterhouse R. V. , Cook R. K.
Published: October 2005

The diffuse sound field as used in standard measurements in reverberant enclosures has been analyzed in terms of two different models, the eigenmode and the free-wave models. Recently the question has been raised as to the extent to which these models are consistent. To investigate these matters, the energy density as a function of position is calculated for axial, tangential, and oblique modes in a rectangular enclosure. The results show that, for a sound field consisting of several overlapping oblique modes, excited by a narrow band of noise, increases of mean sound pressure levels at the walls, edges, and corners of the enclosure are predicted that are in agreement with the results of the free-wave analysis and experiment. It is concluded that the two models are consistent. The inplications of the models, regarding the spatial uniformity of energy, are discussed.

Subject Classification: [43]55.20; [43]20.30.
Analysis of binaural detection models for dependence on interaural target parameters
Authors: Domnitz R. H. , Colburn H. S.
Published: October 2005

It is shown that any binaural detection model in either of two broad classes will, subject to certain approximations, correctly predict relative detection performance for tones masked by noise as a function of interaural tone parameters. A corollary of this result is that any model in either class gains little support by fitting this body of detection data. More meaningful support for any of these models is most likely to come from the adequacy of its predictions for performance as a function of other parameters, such as target frequency, interaural masker parameters, and masker spectrum. It appears that all binaural detection models in the literature are closely related to one of the two classes defined in this paper.

Subject Classification: [43]65.62, [43]65.58, [43]65.35.
Sonar target discrimination by instrumented human divers
Authors: Fish J. F. , Johnson C. S. , Ljungblad D. K.
Published: October 2005

A series of sonar discrimination experiments has been performed using instrumented human divers wearing a helmet with a sending and two receiving transducers. Porpoiselike broad-band clicks, with energy centered about 60 kHz, were projected and the returning echoes stretched electronically in time by a factor of 128 to enable the divers to hear them. Data were collected using metallic plate targets and targets of different geometrical shapes that were previously used in experiments with a porpoise. A comparison of scores indicated that the instrumented divers performed as well as, and in some cases better than, the porpoise.

Subject Classification: [43]65.62; [43]30.82.
Some preliminary observations on the interrelations between two-tone suppression and combination-tone driving in the anteroventral cochlear nucleus of the cat
Authors: Greenwood D. D. , Merzenich M. M. , Roth G. L.
Published: October 2005

For units of the anteroventral cochlear nucleus in the cat—as for primary units—response to a best-frequency tone f1 can be markedly reduced when a higher-frequency suppressing tone f2 of equal or greater intensity is presented simultaneously at a frequency separation corresponding, in the present experiments, to an optimal distance on the basilar membrane of about 0.5–0.8 mm. More data are needed, but this distance does not seem to vary systematically with best frequency and may be related to critical bandwidth. In further preliminary experiments, we have compared unit response to the combination tone, 2f2−f3, formed when f1 is omitted and f3 is added above f2, with the unit’s response to a three-tone stimulus. The three-primary stimulus consists of tones with equispaced frequencies and controllable phase and amplitude relations. Primary tone f1 and combination tone 2f2−f3 coincide at best frequency, while f2 and f3 lie above the tuning curve. The comparison of response to 2f2−f3 ’’alone’’ and of response to the resultant of f1 and 2f2−f3, while f1 phase is varied, allow relative amplitudes to be calculated. They are such that f1 appears suppressed in amplitude by f2 and f3, while 2f2−f3 is correspondingly less than cancellation-tone estimates. For constant f2 level, 2f2−f3 amplitude reaches maximum when f3 amplitude almost equals f2 and decreases markedly as f3 amplitude exceeds f2. Lastly, when the combination tone resultant composed of 2f1−f2 and 3f2−2f3 lies at best frequency, variation in the phase of f1 produces a marked variation in rate of response to the resultant, appearing to parallel psychophysical results obtained by J. L. Goldstein [’’Aural combination tones,’’ in Frequency Analysis and Periodicity Detection in Hearing, edited by R. Plomp and G. F. Smoorenburg (Sijthoff, Leiden, Netherlands, 1969/1970)].

Subject Classification: [43]65.56, [43]65.42, [43]65.75.
Ballistic range experiments on superbooms generated by refraction
Authors: Sanai M. , Toong T.-Y. , Pierce A. D.
Published: October 2005

Experiments are reported which pertain to the phenomenon of enhanced sonic booms or superbooms generated as a result of atmospheric refraction in threshold-Mach-number flights. Such ’’refraction superbooms’’ are created in a ballistic range by firing projectiles at low supersonic speeds into stratified medium of varying sound speed consisting of an inhomogeneous mixture of CO2 and air. The pressure signature recorded by a fast-response transducer inserted in the flow field is studied in conjunction with sets of dual-schlieren pictures obtained simultaneously during each run. The flow field observations indicate that the generated shocks are reflected near the sonic cutoff elevation, where the local sound speed equals the projectile speed, provided that such an elevation exists. The incident shock and its reflected portion join to form a Y-shaped configuration near the cutoff region. Enhanced shock overpressures are detected near the ’’critical altitude’’ where the flow speed behind the shock becomes sonic. A maximum focus factor of 1.7 has been measured for the leading shock which, with some theoretical assumptions, leads to an estimated value of 1.3 for the constant which appears in the Guiraud–Thery scaling law. The same value is also deduced from field data taken during aircraft threshold Mach-number flight by Haglund and Kane. The substantial agreement between the two experimentally derived values of the constant and the theoretical estimate of 1.4 given by Thery, Lecomte, and Reggiani seems to suggest the validity of the above-mentioned scaling law. However, the discrepancy of these numbers with the value of 2.6 derived by Gill and Seebass indicates that further investigation is still needed.

Subject Classification: [43]25.20, [43]25.30; [43]28.55; [43]50.55.
Broadside bearing response pattern of a line array to a cylindrical wave in a random medium
Authors: Fitelson Michael M.
Published: October 2005

In a previous paper, the author examined the bearing response pattern of a line array to a plane wave in a random medium. It was found that random effects are strongest when the source is broadside to the array. In this paper, the corresponding situation for a cylindrical wave is examined. A comparison is made with the plane-wave case.

Subject Classification: [43]30.20, [43]30.40; [43]45.10; [43]20.15; [43]30.82.
Effects of practice on the perception of dichotically presented stop-consonant–vowel syllables
Authors: Porter Robert J. , Troendle Roger , Berlin Charles I.
Published: October 2005

Changes in subjects’ performance on dichotic pairs of CV’s were observed over an eight-week period. Results are of practical significance in that certain performance characteristics were found to remain invariant with practice or reach an asymptotic value after 300–400 trials. The results are also of theoretical interest, however, in that unchanging patterns of response may reflect the operations of processes which are more ’’built-in’’ to the perceptual system, whereas changes in performance with practice may reflect the operation of more ’’plastic’’ processes responsible for phonetic feature decoding. Also emphasized is the importance of considering both the amount of practice and individual differences when interpreting some aspects of dichotic results.

Subject Classification: [43]70.30, [43]70.70.
Self-noise in the solion polarized cathode acoustic linear transducer (SPOCAL) and the use of the SPOCAL in seismometry
Authors: English G. Earle , Adair Robert S.
Published: October 2005

Investigation into the self-noise of a SPOCAL (solion polarized cathode acoustic linear) transducer has identified the mechanisms responsible for this self-noise. Measurements on this transducer have shown it to have a noise threshold of 10−5 μbar, or less than 10−8 mm Hg. Therefore, the linear dynamic range of this type of transducer is 100 dB in the pressure range from 10−5 to 10+3 μbar, with a frequency range from 0.0002 to 3 Hz. The noise thresholds of conventional liquid-pressure measuring devices are several orders of magnitude higher than those of SPOCAL tranducers. The SPOCAL transducer has been applied in a seismometer where it senses the motion of a mercury column as the inertial mass. This SPOCAL seismometer obtains valid data from seismic activity at levels far below the capability of the instruments currently in use.

Subject Classification: [43]85.24, [43]85.40; [43]40.50.
An observation of culvert whistlers
Authors: Kammer D. W. , Erickson J. D. , Vorech B. A. , Walker P. M.
Published: October 2005

Whistles of descending frequency are heard in the resulting sound after presenting a sharp pulse of noise at the entrance to a long cylinder or culvert. The underlying theory of this dispersive behavior of sound is discussed and experimental confirmation is presented.

Subject Classification: [43]20.45.
Swept edge to reduce the noise generated by turbulent flow over the edge
Authors: Filler L.
Published: October 2005

When turbulent fluid flows over an edge, swept at an angle α to the flow direction, it is shown from simple physical arguments that the radiated sound intensity can be reduced by at least a factor of cosα. The anticipated sound reduction depends on the assumption that the normal component of turbulent momentum convected over the edge is the dominant contributor to the edge interaction noise mechanism at high Reynolds numbers. Some preliminary experimental results which confirm the noise reduction are presented for a jet flowing over an edge swept in a sawtooth configuration.

Subject Classification: [43]28.65; [43]50.55.
Speech resynthesis from phoneme-related parameters
Authors: Olive Joseph P. , Spickenagel N.
Published: October 2005

In our recent work on speech analysis and resynthesis, we have been using predictor (LPC) derived area functions to describe the spectrum of the acoustic signal. It has been found that small changes in the value of these parameters do not affect the speech quality. If the acoustic signal is indeed overspecified by these parameters, then bit reduction is achieved by specifying the data less often, at fixed or varied intervals, or with less accuracy; however, we have chosen a scheme where less frequent sampling of the parameters is determined by the properties of the speech mechanism. We have found that if the boundaries of the steady-state portion of the phonemes are found, the steady-state portions, as well as the transitions between the phonemes, can be represented by straight lines. This method allows for the description of the acoustic signal with two sets of points per phoneme. Numerous sentences have been encoded by this method, and the resulting sentences do not sound differently from the sentences from which the data were derived. Such a scheme could be used for a rule-synthesis scheme, as well as for segmentation of speech in speech recognition schemes.

Subject Classification: [43]70.50, [43]70.40.
Biochemistry of neomycin ototoxicity
Authors: Schacht Jochen
Published: October 2005

The biochemical mechanism of neomycin ototoxicity was investigated in vivo and in vitro. In vivo, the incorporation of [32P]–orthophosphate into the phosphoinositide lipids of inner ear tissues was measured in normal and in neomycin-treated guinea pigs. These lipids are believed to be involved in the control of membrane permeability. There was a decrease of labeling of phosphatidylinositol diphosphate in the organ of Corti and stria vascularis following three weeks of daily injections of neomycin (100 mg/kg body weight). In homogenates of organ of Corti and stria vascularis the hydrolysis of phosphatidylinositol diphosphate was blocked and the binding of radioactive calcium was inhibited in the presence of neomycin. Further in vitro studies with brain subfractions demonstrated that the effect on phosphoinositide metabolism is exerted by neomycin and related antibiotics that are toxic to the cochlea and the kidney. The hypothesis is discussed that the ototoxic action of neomycin involves an inhibition of polyphosphoinositide turnover by direct binding of the antibiotic to these lipids.

Subject Classification: [43]65.20.
Ambient noise under Antarctic sea ice
Authors: Kibblewhite A. C. , Jones D. A.
Published: October 2005

Underwater ambient noise spectra are described for data recorded during late spring conditions under the ice sheet in McMurdo Sound. The ambient noise was at all times marked by intense biological activity, but a diurnal component became apparent during a three-day recording period. This noise was found to be similar to that described in Arctic work and undoubtedly arose as the result of surface cracking under the influence of thermal stressing. The characteristics of this noise component, however, were found to differ in certain respects from those reported from comparable Arctic measurements.

Subject Classification: [43]30.20, [43]30.70; [43]28.65.
Sound propagation through a fluctuating stratified ocean: Theory and observation
Authors: Munk W. H. , Zachariasen F.
Published: October 2005

We have derived expressions for the mean-square phase and intensity fluctuations and their spectra for cw sound propagating through a channeled fluctuating ocean. The ’’supereikonal’’ approximation reduces to the geometric optics (eikonal) limit for short acoustic wavelengths: λ≪2πL2H/R and λ≪L2V/(R tan2ϑ), where LH and LV are horizontal and vertical correlation lengths of the fluctuations, R is range, and tanϑ is the ray slope, replacing the traditional (and much more severe) Fresnel condition λ≪2πL2/R for a homogeneous isotropic ocean. The results can be expressed in closed form for an exponentially stratified ocean model and associated ’’canonical sound channel,’’ with superimposed fluctuations from an internal wave model spectrum based on oceanographic observations. The parameters are the stratification scale B, the inertial and buoyancy frequencies ωin and n (z), the scale j* of internal wave mode numbers, and the internal wave energy per unit area. The results are in reasonable agreement with numerical experiments based on the parabolic wave equation. For the ’’singlepath’’ 4-kHz transmission over Cobb Seamount the observed and computed rms fluctuations in phase are 1.6 and 2.5 cycles, respectively; in intensity these are 5.5 and 2.2 dB, respectively, with anomalous intensities measured at high frequencies (’’sporadic’’ multipathing?). For the multipath 406-Hz MIMI transmission, we obtain 4×10−3 and 5×10−3 sec−1, respectively, for the experimentally determined and the computed rms phase rates.

Subject Classification: [43]30.20, [43]30.40; [43]20.15.
Experiments on thermoacoustic arrays with laser excitation
Authors: Muir T. G. , Culbertson C. R. , Clynch J. R.
Published: October 2005

A recent theoretical formulation by Westervelt and Larson predicts the development of highly directive sound beams in water through the thermalization of modulated laser light. The present paper reports the experimental validation of this theory with measurements carried out in a fresh water lake. Additional theory pertinent to practical implementation is also presented and verified. The experimental apparatus includes an optically pumped laser system operating in the conventional mode at wavelengths in either the red or infrared regions of the optical spectrum. Modulation of the stochastic light burst is provided by a half-wave Pockels cell. The acoustic measurements began with an existence test which confirmed that an acoustic signal is produced by thermo-optic demodulation of laser light in the water. The sound pulse was generated in a beam with a width and source level that are in reasonable agreement with theory. Acoustic diffraction effects associated with laser beams of finite size were also examined, as were the nearfield effects of this type of array. The relation of laser technology to further work in the blue–green spectrum is analyzed.

Subject Classification: [43]20.55; [43]85.40; [43]35.65.
Pressure disturbances from a finite cylindrical source
Authors: Remillard Wilfred J.
Published: October 2005

A description of the acoustic pressure versus time is obtained for a finite cylindrical source whose initial overpressure is constant and uniform. Small signal analysis is used and the medium is considered dissipationless. The results show a short leading condensation followed immediately by a rarefactive impulse with a long tail which ends in a second rarefactive pulse of smaller amplitude. The analytical results are amenable to numerical methods for obtaining pressure disturbances from cylindrical sources of given lengths and radii.

Subject Classifacation: [43]20.55, [43]20.15.
Analysis of trapped-energy resonators operating in overtones of coupled thickness-shear and thickness-twist
Authors: Tiersten H. F.
Published: October 2005

The equations of three-dimensional linear piezoelectricity are applied in the analysis of trapped-energy resonators with rectangular electrodes vibrating in coupled thickness shear and thickness twist in the vicinity of the fundmantal and odd overtone thickness-shear frequencies. Closed form asymptotic expressions for the frequency wave-number dispersion relations for the fundamental and odd overtone coupled thickness-shear and thickness-twist waves near cutoff are obtained for both the electroded and unelectroded regions of the trapped-energy resonator. The influence of piezoelectric stiffening, electrode mass loading, and electrical shorting is included in the analysis. Simple approximate boundary conditions at a junction between an electroded and unelectroded region of the plate are obtained in a manner exhibiting the natural limitations inherent in the approximation. In order that these boundary conditions can be satisfied at each such junction, in the adjacent regions the wave numbers in the direction of the junction line are assumed to be the same. The boundary conditions to be satisfied at the junctions between the unelectroded corner region and the unelectroded regions adjacent to the electroded region are obtained from an extended version of the variational principle of linear piezoelectricity. These latter conditions result in the form of the solution in the corner region. One result of the foregoing analysis is the determination of a two-dimensional condition which is a generalization of Bechmann’s number in one dimension. The above-mentioned dispersion relations and edge conditions are applied in the analysis of the steady-state vibrations of a trapped-energy resonator and a lumped parameter representation of the admittance, which is valid in the vicinity of a resonance, is obtained.

Subject Classification: [43]40.24; [43]85.52, [43]85.32.
Transient response of the basilar membrane measured in squirrel monkeys using the Mössbauer effect
Authors: Robles Luis , Rhode William S. , Geisler C. Daniel
Published: October 2005

Measurements of the transient response of the basilar membrane were conducted using the Mössbauer effect on 33 squirrel monkeys using an experimental preparation identical to that of Rhode (1971). The stimuli were acoustic clicks 150 μsec in duration repeated 100 000–400 000 times. The amplitude of the click was varied and the responses of the malleus and of the basilar membrane at a point in the basal turn were measured. The basilar membrane’s click response is oscillatory, with a period near that of the characteristic frequency. The first few response peaks behave almost linearly with stimulus intensity, while the later peaks exhibit a pronounced nonlinearity. This behavior is shown to be consistent with the nonlinearity reported using steady-state measurement methods (Rhode, 1971). The transient response observed in some of the preparations was very lightly damped; however, a wide range in the damping of the responses was found in the different animals. A progressive increase in the rate of decay of the transient response with the duration of the experiment was observed. Any damage to the cochlea also resulted in increased damping. The measured cochlear delay time of 300–390 μsec agrees with that derived from phase curves of the transfer ratio measured with steady-state methods.

Subject Classification: [43]65.26, [43]65.20.
Inferred response polarities of cochlear hair cells
Authors: Sokolich W. G. , Hamernik R. P. , Zwislocki J. J. , Schmiedt R. A.
Published: October 2005

Single-fiber responses were recorded from the auditory nerves of kanamycin-treated gerbils whose cochleas were subsequently processed for histological examination. On the basis of their abnormal responses to inferred trapezoidal displacements of the basilar membrane, the contacted fibers were classified according to that direction of basilar-membrane deflection that was associated with their excitation. A frequency–distance map was constructed for the gerbil’s cochlea with the help of cochlear-microphonic recordings and was used to infer the location of the hair cells innervated by the contacted fibers. Our correlations indicate that fibers innervating cochlear regions substantially depleted of outer hair cells were abnormal and were scala-vestibuli excitatory. Furthermore, fibers innervating cochlear regions containing full or nearly full complements of both inner and outer hair cells were either abnormal and scala-tympani excitatory, or were normal. These response polarities are consistent with the previously proposed polarity-opposition model of interaction between inner and outer hair cells in the cochlea.

Subject Classification: [43]65.28, [43]65.35, [43]65.40, [43]65.42, [43]65.59.
Measurements of hydrodynamic noise from submerged hydrofoils
Authors: Barker Steven J.
Published: October 2005

This paper presents the results of an experimental study of hydrodynamic noise conducted in the High-Speed Water Tunnel of the California Institute of Technology. The objective of the test program was to measure some of the basic characteristics of noise radiated from submerged hydrofoils, both fully wetted and cavitating. Measurements of fully wetted hydrodynamic noise are difficult to make due to the low intensities, but the very low background noise level of the Caltech tunnel makes it possible to measure this noise under some conditions. An increase in the angle of attack of a hydrofoil was found to produce a slight increase in noise spectrum level at high frequencies. An increase in surface roughness produced a more significant increase over a wider frequency range. Noise was measured for three distinct types of hydrofoil cavitation: blade surface cavitation, wake cavitation, and trailing vortex cavitation. Foil vibration was found to be important in blade surface cavitation, but not in the other forms. Both blade surface and wake cavitation have spectral peaks at a Strouhal number based on a cavity length of 0.5. Trailing vortex cavitation is found to be a relatively weak source of noise, owing to the fact that in the water tunnel this type of cavitation is gaseous in nature.

Subject Classification: [43]30.70, [43]30.85, [43]30.50.
Sound radiation from a semi-infinite circular pipe having an arbitrary profile of orifice
Authors: Ando Y. , Koizumi T.
Published: October 2005

A general solution for the sound radiated from a circular pipe having an arbitrary inside profile of orifice is obtained by the use of Laplace transforms and the Wiener–Hopf technique. The pipe may include vibrating surfaces. Results are calculated for the velocity potential at a large distance from the orifice and for the reflection coefficient for the dominant-mode component of the velocity potential in the pipe. The solution is applicable, for example, to the design of an acoustic transducer, and for noise control from the orifice. Some numerical results for the velocity potential of a model loudspeaker and for the excess attenuation of a muffler near the open end of a pipe are presented graphically.

Subject Classification:[43]20.55, [43]20.15.
Radiation of difference-frequency sound generated by nonlinear interaction in a silicone rubber cylinder
Authors: Ryder J. D. , Rogers Peter H. , Jarzynski J.
Published: October 2005

In this paper we describe an experimental and theoretical investigation of the parametric signal generated in one medium, a silicone rubber cylinder, and radiated into a second medium, water. The primary waves (∠1.4 MHz) are confined to a narrow region around the axis of the cylinder and, because of the relatively high absorption at these frequencies, are largely attenuated before reaching the end of the cylinder. The silicone rubber cylinder serves two purposes. First, the low sound speed (∠1000 m/sec) and high parameter of nonlinearity (1+B/2A?5) of the silicone rubber makes the virtual sources more than seven times as strong as they would be in water. Second, because the sound speed in silicone rubber is less than that of the surrounding water, the silicone rubber cylinder acts as a slow waveguide antenna for the difference-frequency waves. The system is analyzed by numerically solving the system of equations obtained by coupling the surface Helmholtz integral equation for the interior of the silicone cylinder (which includes the virtual sourcesI with the integral equation for the region exterior to the cylinder. Experimental results obtained for difference frequencies between 10 and 20 kHz compare favorably with theory.

Subject Classification: [43]25.35, [43]25.15; [43]30.75.
Acoustic radiation from submerged plates. I. Influence of leaky wave poles
Authors: Stuart Alan D.
Published: October 2005

Leaky wave poles are defined as those singularities of the acoustic admittance of a fluid-loaded infinite plate that are located on the bottom Riemann sheet of the complex wavenumber plane and can appear near the saddle point of the complex path of steepest descent. These poles are shown to represent only the real, propagating modes in an unloaded plate. It is shown that for a point or line excited plate the value of leaky wave poles and their location relative to the saddle point are sufficient parameters to explicitly describe the acoustic radiation from submerged plates. This paper analyzes the leaky wave poles of both the Timoshenko–Mindlin plate equation and the classical plate equation.

Subject Classification: [43]30.50; [43]40.24.
Identification of vowels excerpted from neutral and nasal contexts
Authors: Bond Z. S.
Published: October 2005

In a number of previous studies, subjects have been shown to have some difficulty in identifying vowels presented in isolation, even when the vowels have been produced with considerable precision. However, equivalent precision of utterance can not be assumed in more ordinary speech situations. In the present study, the effect of two consonantal contexts on the identifiability of vowels was investigated. Six speakers produced ten monophthongal English vowels in two different phonetic contexts: neutral (h——d) and nasal. The vowels were excerpted from context and presented for identification. Subjects found the phonetic context to affect vowel identifiability significantly.

Subject Classification: [43]70.30, [43]70.40, [43]70.70.
The photophone–an optical telephone receiver
Authors: Kleinman D. A. , Nelson D. F.
Published: October 2005

A theoretical discussion is given of optical telephone receivers employing the optoacoustic effect, which are here called photophones, for use in an optical-fiber telephone subscriber loop. The basic receiver consists of an absorption cell, a response-equalizing device such as a gas column or diaphragm, a tapered acoustic tube acting as a transformer, and an earpiece similar to a conventional telephone earpiece including a response-equalizing device. These photophones are designed to give a flat (3-dB) response to intensity modulated light over the telephone voice band 300–3300 Hz. The optoacoustic effect is treated on the basis of a pseudogas model for solid absorbers in the form of a fine mesh disbusrsed in a gas. We find that the sensitivity (the optical power modulation required to produce a sound pressure level SPL = 81 dB in a closed volume of 6 cm3, representing the earpiece pressed against the ear) is 2.8 and 0.9 mW for the air-filled and xenon-filled photophones, respectively.

Subject Classification: [43]85.76, [43]85.40, [43]85.60; [43]35.65.
Effect of flow on the acoustic reflection coefficient at duct inlet
Authors: Bohn M. S. , Zukoski E. E.
Published: October 2005

The effect of duch Mach number upon the acoustic reflection coefficient at the inlet of a duct with mean flow is investiagted. An analysis, which models the duct inlet as a very short, one-dimensional nozzle over which the mean flow is accelerated from rest, gives good agreement with some recent experimental results. Discrepancies between the analysis and he experimental results are discussed in terms of radiation losses at the inlet and real fluid-flow effects within the duct.

Subject Classification: [43]28.60; [43]20.30.
Reply to ’’Comments on ’Influence of rotary inertia and shear deformation on acoustic transmission through a plate’ ’’ [J. Acoust. Soc. Am. 59, 1500–1501 (1976)]
Authors: Stepanishen P. R.
Published: October 2005

The expression and numerical results in the original letter were based on the use of Timoshenko–Mindlin plate theory and thus have an inherent frequency–plate-thickness limitation when compared to results based on the use of elasticity theory. This limitation, which is noted by Young, was already noted, however, in the concluding section of the original letter. In addition it is noted that the second acoustic coincidence lobe was not attributed in the original letter to a dilatational mode, but was attributed to a flexural wave whose phase velocity at high frequencies approaches the velocity of a dilatational wave in an infinite elastic medium.

Subject Classification: [43]30.50; [43]20.60; [43]40.24; [43]20.30.
Reply to ’’Comments on ’Vibration of generally orthotropic skew plates’ ’’ ]
Authors: Srinivasan R≳ S. , Ramachandran S. V.
Published: October 2005

Subject Classification: [43]40.24.
Reactions of pronghorn antelope to helicopter overflight
Authors: Luz George A. , Smith J. Barry
Published: October 2005

Photographic observations of pronghorn antelope suggested mild disturbance by helicopter noise levels at approximately 60-dBA and strong reactions at approximately 77-dBA.

Subject Classification: [43]80.60; [43]50.50.
Correlation of acoustic wavefront and signal time-base instabilities in the ocean
Authors: Williams Ross E. , Wei Chao H.
Published: October 2005

Wavefront fluctuations, rotations, and distortions, measured for a particular arrival in the multipath set for long-range propagation, were cross correlated with acoustic-signal time-base distortions for the same arrival. Although the wavefront perturbations contain higher frequency components than for the signal time-base fluctuations, significant cross correlation amplitudes were found for time and rotation, time and distortion, and distortion and rotation cross correlations. The results demonstrate that common causes, such as tides, overtides, and internal waves, underlie both the temporal and spatial perturbations of the acoustic signal. Although these perturbations were significantly correlated in a high percentage of the tests, the degree of correlation between them was not stable over periods of days or weeks.

Subject Classification:[43]30.20, [43]60.20.
Model for predicting the reflection of ultrasonic pulses from a body of known shape
Authors: Johnson D. M.
Published: October 2005

An approximate model for determining the response functions of reflectors of known shape has been used to provide theoretical support for experimental investigations of flaw characterization. The reflection of broad-band ultrasonic pulses from an object can result in modifications to both the frequency spectrum and phase information in the pulses. These changes are largely controlled by the parameters of the reflector, and relating these factors has been the subject of many experimental investigations. Within the fundamental approximations, the model can readily be applied to any reflector of known shape and provides a simple interpretation of what is physically occurring. It has the advantage that additional experimental factors can be included to determine their effect on the results.

Subject Classification: [43]35.26; [43]20.30; [43]35.80.
Theorem on the scattering and the absorption cross section for scattering of plane, time-harmonic, elastic waves
Authors: Tan T. H.
Published: October 2005

In a homogeneous, isotropic, perfectly elastic medium a scattering obstacle of finite extent is present. When a plane, time-harmonic, elastic compressional (P) or shear (S) wave is incident on it, the extinction cross section (i.e., the sum of the scattering and the absorption cross section) of the obstacle is directly related to the far-zone amplitude of the particle displacement of the scattered wave, observed exactly behind the obstacle. This relationship is discussed. In spite of the fact that in elastodynamic scattering the scattered P wave as well as the scattered s wave contribute to the time-averaged scattered power, the extinction cross section appears to depend only on the value of that farfield scattered-wave amplitude which is of the same type (P or S) as the incident wave.

Subject Classification: [43]20.15, [43]20.30.
Use of a spherical concave reflector for jet-noise-source distribution diagnosis
Authors: Chu W. T. , Kaplan R. E.
Published: October 2005

An account on the development of a directional microphone system for jet-noise-source strength distribution measurements is given. The system selected is based on the imaging principle of a spherical concave reflector. As expected, the system is diffraction limited; a loss of resolution results. A special technique is discussed to recover the axial-source strength distribution from the diffracted data. Sample experiments are presented to show the successful application of such a system for jet noise measurements.

Subject Classification: [43]28.65; [43]50.55; [43]85.62.
Spatial interfrequency correlation effects in a surface-scatter channel
Authors: McDonald J. F. , Tuteur F. B. , Zornig J. G.
Published: October 2005

The effect of spatial separation on the cross correlation between the system response functions for a two-receiver surface-scatter channel is investigated. The system response at the two receivers is determined for all possible pairs of frequencies. The analysis assumes relatively close separation of receivers and uses the Fresnel-corrected model for surface scatter in the specular direction. The surface is assumed to be Gaussian, with typical size of boundary deformations small compared to typical Fresnel zones.The analysis shows that the correlation is approximately maximum for zero-frequency separation and drops off at a rate determined by the reverberation time. For small reverberation times and small grazing angles correlation may extend over fairly large values of frequency difference. The effect of spatial separation is generally a reduction in correlation and a more rapid decrease of correlation with frequency, but this can be compensated to some extent by time shift between the two system responses. Experimental evidence is included to support the theoretical predictions presented.

Subject Classification: [43]30.20; [43]20.15; [43]60.20.
Evaluation of transducer window materials
Authors: Mikeska E. Eugene , Behrens John A.
Published: October 2005

Acoustic measurements of insertion loss and echo reduction at normal incidence were made for thin plates of eight materials for evaluation of their use in underwater sound transducers in the frequency range 50–500 kHz. Materials tested included Lucite; silicone rubber RTV– 560; the commercial polyurethane products PRC–1527, CPC–19, Scotchcast 8, and Scotchcast 221; and two of these materials with talc added during curing to vary the properties. Values of longitudinal sound velocity, attenuation constant, and characteristic impedance are derived from comparison of theoretical and measured characteristics.

Subject Classification: [43]30.30; [43]40.55; [43]55.75; [43]85.40.
Mode synthesis technique for dynamic analysis of structures
Authors: Agrawal B. N.
Published: October 2005

A mode synthesis technique is presented for determining the normal modes, natural frequencies, and responses of three-dimensional complex structure with flexible joints. Lagrange’s equations are used to develop the equations of motion
Whispering Gallery wave modes on elastic cylinders
Authors: Dickey J. W. , Frisk G. V. , Überall H.
Published: October 2005

We present an analytic and numerical study of Whispering Gallery-type surface- wave modes on solid elastic cylinders imbedded in a fluid. The complex wave numbers of these waves are obtained for the case of high frequencies (ka≳15), including both their attenuation and dispersion curves for the phase velocities. It is shown that there are two different groups of Whispering Gallery modes whose wave numbers in the limit of infinite frequency or infinite cylinder radius approach the corresponding wave numbers of compressional and shear bulk waves in the cylinder material.

Subject Classification: [43]40.20; [43]30.50; [43]40.55; [43]20.15; [43]35.54.
Transmissibility across clamped circular plates with central loading masses and various rib configurations
Authors: Ochs J. B. , Snowdon J. C. , Kerlin R. L.
Published: October 2005

The tranmissibility between the midpoint and the boundary of thin, symmetrically vibrating, circular, aluminum plates of identical dimensions has been determined experimentally in the frequency range 16–2000 Hz. The plates were clamped at their boundaries and loaded symmetrically by concentrated masses or by distributed masses (ribs) of various configurations. The loading masses were always equal to the plate mass, so that their effectiveness in reducing transmissibility could be evaluated as a function of their geometry. Consideration was given to continuous and segmented effectiveness in reducing transmissibility could be evaluated as a function ribs. The transmissibilities across plates loaded centrally by cylindircal masses of small and intentionally large contact areas, and by continuous and segmented circular ribs of small and large diameters, agreed closely with prediction, encouraging belief in the validity of the experimental results obtained for the remaining plates loaded by noncircular ribs, which had theoretically intractable geometries. The transmissibilities across an unloaded plate and a plate plus damping tile also agreed satisfactorily with prediction, even though the transmissibility across the damped plate was calculated from an expression developed for a homogeneous plate with internal damping. The greatest overall reductions in transmissibility were provided by the central loading masses, particularly by the mass having small contact area. By comparison, the reductions provided by the various rib configurations were disappointing; only the performance of the triangular rib and of the small circular rib approached that of the central masses, suggesting use of these ribs when access to the plate center is necessary.

Subject Classification: [43]40.24, [43]40.20.
Huygens’ principle, radiation conditions, and integral formulas for the scattering of elastic waves
Authors: Pao Yih-Hsing , Varatharajulu Vasundara
Published: October 2005

Helmholtz- and Kirchhoff-type integral formulas are presented for elastic waves in isotropic and anisotropic solids. The displacement vector field at points interior and exterior to a region bounded by a closed surface is expressed in terms of a volume integral of the body sources and a surface integral of the sources on the closed surface, namely, the traction and the displacement. The kernels of these integrals are the well-known Green’s displacement dyadic and a third rank Green’s stress tensor. The latter is related to the former by generalized Hooke’s law. From these formulas radiation conditions for both steady-state and transient elastic waves are established in terms of the traction, displacement, and particle velocity. In the Kirchhoff-type formula, the retardation in time for the surface and volume sources is made with respect to the travel times for dilatational and shear waves, respectively. This clearly illustrates Huygens’ principle for the two wave fronts of the elastic wave field.

Subject Classification: [43]40.20, [43]40.55; [43]20.15.
Fourth-order dispersion of free longitudinal waves in a long orthotropic bar of rectangular cross section
Authors: Zuckerwar Allan J.
Published: October 2005

A perturbation technique described previously is applied to find the dispersion of free longitudinal waves in a long orthotropic bar of rectangular cross section as far as the fourth order of approximation. First the second-order equations of motion and equations of compatibility are solved to find the second-order stress distributions; then these are used to derive the exact second- and fourth-order dispersion terms. The second- order stresses are related to a homogeneous and a nonhomogeneous potential function. The homogeneous potential function may be described by one of three analytical expressions, depending upon whether the following combination of elastic compliances is less than, greater than, or equal to unity:

A = (s11s33−s13 2) (s22s33−s23 2) / [(s12s33−s13s23) +(1/2) s33s66]2.

Measurements of the first two frequencies of two potassium chloride specimens, having different major orientations, are compared with theoretical predictions; the percent differences are 0.06%, 0.12%, 0.07%, and <0.01%, all of which lie well within the bounds permitted by the uncertainties in the governing parameters.

Subject Classification: [43]40.22, [43]40.20; [43]20.15.
Effect of air flow, panel curvature, and internal pressurization on field-incidence transmission loss
Authors: Koval Leslie R.
Published: October 2005

In the context of sound transmission through aircraft fuselage panels, equations for the field-incidence transmission loss (TL) of a single-walled panel are derived that include the effects of external air flow, panel curvature, and internal fuselage pressurization. These effects are incorporated into the classical equations for the TL of single panels, and the resulting double integral for field-incidence TL is numerically evaluated for a specific set of parameters. Flow is shown to provide a modest increase in TL that is uniform with frequency up to the critical frequency. The increase is about 2 dB at Mach number M = 0.5, and about 3.5 dB at M = l. Above the critical frequency where TL is damping controlled, the increase can be slightly larger at certain frequencies. Curvature is found to stiffen the panel, thereby increasing the TL at low frequencies, but also to introduce a dip (analogous to the coincidence dip at the critical frequency) at the ’’ring frequency’’ of a full cylinder having the same radius as the panel. This effect, up to now qualitatively understood, can now be quantitatively estimated. Pressurization appears to produce a slight decrease in TL throughout the frequency range, and also slightly shifts the dips at the critical frequency and at the ring frequency.

Subject Classification: [43]50.50, [43]50.45; [43]55.80, [43]55.75.
Double eigenvalues of soft circular ducts containing uniform flow and sheared flow
Authors: Tseo Gus G.
Published: October 2005

Numerical methods to compute double eigenvalues for circular ducts containing uniform and sheared flow are presented. A technique to verify both the maximum exponential decay and the double eigenvalue, impedance, and attenuation in ducts of different sizes are presented and discussed. For well cut-on modes in a uniform-flow duct, the impedance velocity by a simple relationship suggested in a previous study. However, in a sheared-flow duct, optimum impedances are found to have much smaller values than in the uniform-flow case.

Subject Classification: [43]50.40; [43]20.45, [43]20.40.