bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Influence of Lattice Defects upon Third-Order Elastic Constants
Authors: Bradfield G. , Stern R.
Published: October 2005

The total influence of lattice defects on the third-order elastic constants of EN 26 steel is estimated to be less than 5%, as shown by an investigation involving two different acoustic techniques.
Solutions for Sound-Radiation Problems by Integral Equations at the Critical Wavenumbers
Authors: Chertock George
Published: October 2005

Numerical calculations of sound radiation from vibrating surfaces by solution of an integral equation can become indeterminant or give spurious results if the wavenumber is too close to one of an infinite set of critical wavenumbers. Several methods are described for obtaining correct solutions at these critical wavenumbers.
Fatigue Damage under Wide-Band Random Stress
Authors: Bernard Michael C. , Shipley John W.
Published: October 2005

Fatigue damage for a wide-band random-stress process is considered under the limitations of classical damage theory. A method of obtaining a lower-bound estimate of the expected fatigue from the statistical parameters of a stress process such as the power spectral density is derived without employing extreme statistics. A method proposed by H. C. Schjeldrup for assessing fatigue damage due to a wide-band stress process is discussed and a simplification of this method is used to obtain an upper-bound estimate of the expected fatigue life. These two estimates are compared for some typical stress spectra.
Comparison of Mechanical Coupling Factor by Two Methods
Authors: Khabbaz Ghassan R.
Published: October 2005

Mechanical coupling factors needed in the statistical-energy method for the determination of the response of vehicles to acoustic fields are very difficult to calculate. The coupling factor for a simple structure was calculated by two methods and the answers are compared. They differ by a factor of 5. This indicates the difficulty and uncertainty encountered in the calculation of the coupling loss factor.
First-Passage Time Problem
Authors: Yang Jann-Nan , Shinozuka Masanobu
Published: October 2005

A well-posed boundary-value problem is obtained of the first-passage probability for a linear single-degree-of-freedom vibratory system with a linear viscous damping and subjected to either stationary or nonstationary white-noise excitation.
Excitation and Detection of Surface Elastic Waves in Piezoelectric Crystals
Authors: Joshi S. G. , White R. M.
Published: October 2005

The amplitude of the surface elastic wave produced by the application of an alternating voltage to an interdigital arrangement of electrodes on the surface of a piezoelectric medium is determined. The electric field produced by the surface electrodes is calculated subject to the assumption that the piezoelectric coupling of the material can be neglected. This electric field acts as the forcing term for the inhomogeneous elastic equation, which is then solved to obtain the amplitude of the surface wave generated by the transducer. A reciprocal relationship between the excitation and detection problems is used to obtain the power extracted from the surface wave by an interdigital arrangement of surface electrodes. Measurements made on single crystals of quartz and cadmium sulfide are found to be in good agreement with theoretical predictions. The maximum value of the product (efficiency×fractional bandwidth) for a surface-wave transducer is calculated. For an interdigital surface-wave transducer on the basal plane of CdS, the maximum value of this product is found to be 7.8×10−2. It is shown that one can connect linear pairs of surface electrodes in an appropriate binary code so as to obtain high efficiency and large bandwidth transducers.
Free Vibrations of Ring- and-Stringer-Stiffened Conical Shells
Authors: Crenwelge O. E. , Muster D.
Published: October 2005

Strain-displacement relations are developed for a thin truncated circular conical shell and its reinforcing rings and stringers. Using these relations in an energy approach, methods are developed for determining the resonant frequencies of simply-supported conical shells in unstiffened, ring stiffened, or ring-and-stringer-stiffened configurations. The stiffeners may be either widely separated or closely spaced. Computed values obtained using these methods are compared with the results of a series of experiments on ring-stiffened and ring-and-stringer-stiffened conical shells.
Transmission of Noise from a Turbulent Boundary Layer through a Flexible Plate into a Closed Cavity
Authors: Dowell E. H.
Published: October 2005

The title problem is investigated, emphasizing two effects that are usually ignored in the literature. These are (i) nonlinear plate stiffness and (ii) mutual interaction between the plate and external and/or internal (cavity) air flow. The method of analysis employs modal expansions for the plate and cavity (air) motions, with the solution effected in the time (rather than the frequency) domain. The external flow-pressure perturbations due to the plate motion are assumed to be described adequately by classical acoustic theory including convection effects. A discussion is given as to when the two effects will be important and a practical, numerical example is worked out to illustrate the method.
Measurements on the Effect of Transducer Size on the Resolution of Boundary-Layer Pressure Fluctuations
Authors: Geib F. E.
Published: October 2005

The response of a flush-mounted transducer to the pressure field in a turbulent boundary layer is known to depend on the spatial and temporal characteristics of the transducer. This paper presents an experimental study of this dependence. The reduced data are presented in a manner similar to that used by Corcos to present his estimation of the response of transducers to a corresponding pressure field.
Comments on Two Letters by Neubauer on Creeping and Circumferential Waves [J. Acoust. Soc. Amer. 44, 298(L) (1968); 1150(L) (1968)]
Authors: Bunney R. E.
Published: October 2005

Neubauer has offered some interesting circumstantial evidence for the existence of several surface waves. However, there remain discrepancies between his results and known theory. He must also present stronger evidence than that given to discriminate between his surface waves and other phenomena explainable by the same data. His use of the schlieren technique is very promising, but he does not take full advantage of its potential.
DYNAMIC WIRE MEASUREMENTS BY NEW INSPECTION TECHNIQUES
Authors: Watkins L. S. , Zaleckas V. J.
Published: October 2005

The intense, coherent light of lasers permits the formation of clear, bright diffraction patterns. These diffraction phenomena, formerly considered an optical limitation, have been transformed into a useful measuring tool by laser radiation.
Context and Sequence Effects with an Adaptive Threshold Procedure
Authors: Campbell Richard A.
Published: October 2005

The responses of human observers while tracking 75%-correct thresholds using a block up-and-down adaptive procedure has been examined. Three signals (wide-band noise, narrow band noise, and a 2000-Hz sinusoid) were used with a continuous or a gated wide-band masking noise at various levels. A strong bias in favor of the “2” response in the two-interval paradigm and the “NO” response in the YES NO paradigm was consistently observed. Subjects also tended to follow correct responses with correct responses and vice versa. These data suggest that, although the subjects were supposedly performing a two-interval task, they were actually attending to only one interval, most frequently the first, on each trial.
Effect of Air Bubbles in the External Auditory Meatus on Underwater Hearing Thresholds
Authors: Hollien Harry , Brandi John F.
Published: October 2005

Thresholds of human hearing were obtained underwater for two conditions: (1) with the external auditory meatus completely water filled and (2) with a bubble of air trapped against the tympanic membrane. The first condition was accomplished by forcibly irrigating the external meatus underwater the second, by placing plugs in the ears in order to encapsulate air in the meatus until the head was underwater and the test with the plugs removed) initiated. Subjects were seven divers who were tested in DICORS at a depth of 12 ft; threshold SPLs were obtained free field by a modified Békésy technique for the frequencies 125 Hz, 250 Hz, and 1, 2, and 8 kHz. Threshold shifts (re air) for both conditions of underwater hearing were consistent with those previously reported. SPLs for the two experimental conditions were virtually identical for all frequencies except 250 Hz, where hearing was 6 dB better for the water-filled meatus condition. Apparently, the presence or absence of air bubbles in the external meatus contributes little if anything to underwater hearing thresholds.
Further Observations Concerned with Auditory Fatigue During Vocal and Nonvocal Speech Activities
Authors: Luterman Barry F. , Karlovich Raymond S.
Published: October 2005

Eleven female subject, with normal hearing sensitivity were exposed to 90 dB SL 2000- and 4000-Hz fatigue stimuli for 3 min; temporary threshold shifts (TTS) were measured one-half octave above the fatigue frequency. Over several experimental sessions separated by at least 24 h, each subject performed each of the following tasks during the exposure time for each fatigue frequency: Reading a passage aloud (RA); Reading a passage silently (RS); Reading a passage silently while articulating the words without voicing or whispering (RSA); Reverie which involved no reading (REV). The RA task produced significantly greater TTS than the other task conditions when the fatigue frequency was 4000 Hz, implying that transmission of the fatigue stimulus was enhanced, perhaps owing to impedance changes resulting from contraction of the middle-ear muscles during speech production. The RA-task condition produced consistently, but not significantly, less TTS than the other task conditions when the fatigue stimulus was 2000 Hz, which might indicate that transmission of the fatigue stimulus was being slightly attenuated during speech production. The data are discussed in terms of a hypothesis indicating that speech production alters the impedance of the auditory system, hence altering the transmission of sound. A TTS paradigm incorporating speech activities may be an indirect but useful method for assessing the sound transmission properties of the human auditory system.
Auditory Random-Walk Discrimination
Authors: Pollack Irwin
Published: October 2005

One-dimensional random-walk temporal sequences were generated by cumulating successive perturbations within a jitter discrimination test. Random-walk discrimination may be substantially superior to jitter discrimination. This superiority is nullified: (a) at extreme low and high interpulse intervals; (b) at high reference jitter levels; and (c) when the range of the random walk is curtailed. The superiority of random-walk detection is presumably related to the increased temporal dispersion about the mean interpulse interval. Restriction of the random walk reduces its superiority over jitter detection.
Acoustic Properties of Certain VCC Utterances
Authors: Menon K. M. N. , Jensen Paul J. , Dew Donald
Published: October 2005

Acoustic properties of certain VCC utterances were investigated by means of spectrographic analysis. The speech stimuli consisted of the consonant clusters /-sp, -st, -sk/ in combination with the vowels /i e æ ɑ o u/ spoken by ten adult male speakers of American English. Measurements were made of the duration of silent interval and burst frequency of the plosives, the lower cutoff frequency and transitional frequency of the fricative, and the frequencies and transitions of the vowel formants. The effects of coarticulation of each of the phonetic segments on the others was a particular interest. The results were compared to those of earlier studies employing similar stimuli synthetically produced. It was found that the period of silent interval was on the average 13 greater for /p/ as compared to /t/ and /k/. The frequency of the plosive bursts occurred in three distinct regions: /t/ in the higher, /p/ in the lower, and /k/ in the intermediate region on the frequency scale. The lower cutoff frequency of /s/ was strongly influenced by the nature of the preceding vowel; a much lower value occurred following rounded vowels. Final plosives seemed to have little influence on the lower cutoff frequency of /s/. There was a strong falling transition in /s/ before /p/; no significant transition was found in /s/ before /t/ or /k/. F2 locus of /s/ was found at about 1400 Hz; no such unique F1 locus of /s/ was indicated.
Perceived Pitch of Whispered Vowels
Authors: Thomas I. B.
Published: October 2005

Listeners were required to determine the pitch of the whispered vowels of a male and a female speaker. Continuous tape loops of the vowels were played to the listeners who were then asked to specify the perceived pitch by comparison with that of a pure-tone oscillator. Initially, the perceived pitch of each of the vowels corresponded very closely to F2 as measured from spectrograms. In subsequent tests in which the listeners were told to expect more than one pitch, two listeners identified additional pitches corresponding to F1 for the vowels /a/ and /ɔ/ of both speakers. The accuracy and consistency of formant determination using this simple “listen-and-compare” method compare favorably with results obtainable from more complex analysis procedures.
Four-Pole Properties of an Electroacoustic Delay Line with Plane-Concave Transducers
Authors: van der Pauw L. J.
Published: October 2005

The transfer impedance of conventional delay lines with plane-parallel transducers exhibits, as a function of frequency, typical zeros, which limit the useful relative bandwidth. It is shown in this paper that the transfer impedance of a delay line with plane concave transducers does not have these zeros and for that reason can have a much larger relative bandwidth.
Spatial Averaging in a Diffuse Sound Field
Authors: Lubman David
Published: October 2005

Estimation of mean pressure squared in a reverberation room embodies averages over time, frequency, and space. The benefits of space averaging may be expressed by a number Neq—the equivalent number of uncorrelated samples (degrees of freedom) resulting from space averaging. The variance of the estimated mean pressure squared is that due to frequency averaging alone, Vf2, divided by Neq. A method for finding Neq is presented that is based upon knowledge of the spatial covariance function for pressure squared. Results are given for the cases of sampling at discrete locations, and for continuous integration over a straight line traverse. These results are based upon a covariance function that is intended for pure-tone or extremely narrow-band noise excitation. It is shown that Neq for continuous integration along a straight-line traverse of length L is approximately equivalent to that for discrete sampling at half-wavelength intervals on the same line.
Acoustic Field Produced by an Arbitrary Body in Good Vibration. I. Theory and Three-Dimensional Synthesis
Authors: Kuo E. Y. T.
Published: October 2005

Arbitrary-body acoustic radiation is simulated by an inside source distribution whose field satisfies the boundary vibration. Together with the expansion of Kirchoff's integrand in the ratio of source points and observation point locations, a proposed perturbation process is shown to converge for ratios that are less than unity. Within the frame of perturbation, the class of vibration (good vibration) was shown to bypass the eigenvalue difficulties by analytical inversion. The results are consistent with spherical pulsation, spherical oscillation, and Morse's solution for spherical-cap vibration. Application of the method to transient analysis is also indicated.
Effective Dynamic Properties of a Fiber-Reinforced Material and the Propagation of Sinusoidal Waves
Authors: Mok Chi Hung
Published: October 2005

A theoretical study is presented on the propagation of a plane sinusoidal wave through a material that is reinforced with parallel fibers in one direction. The wave propagates in a direction normal to the fibers, and both fiber and matrix are made of linear elastic materials. An integral formulation for the scattered-wave solution of an isolated fiber is used to study the multiple scattering in an infinite slab of the composite material. The transmitted and reflected waves from the composite and from a homogeneous slab are shown to be similar. By matching the two sets of results, formulas expressed in terms of the isolated-fiber solution are derived for the wave speed, the effective density, and the modulus of the composite. In general, the effective density and modulus so defined are complex numbers and depend on the wave frequency. This fact indicates the possible existence of dissipation and dispersion in the composite under dynamic loadings. A series solution is presented for a composite containing circular fibers, and approximate closed form results are obtained for the limiting case of very long wavelength. As expected, the material does not exhibit dispersion and dissipation at this limit.
Transmission of Plane Waves through Layered Linear Viscoelastic Media
Authors: Shaw R. P. , Bugl P.
Published: October 2005

The two-dimensional propagation of time-harmonic plane waves through a plane horizontally layered viscoelastic medium is discussed. The problem is formulated as the equivalent elastic plane-strain case with modified Lamé constants, which are complex and frequency dependent, replacing the usual elastic Lamé constants. Rather than use potentials, incident angles, etc., we formulate the problem directly in terms of stresses and displacements and solve it by using matrix methods. This approach is felt to be more direct and leads to some interesting conclusions. If the incident wave is not attenuated in the direction parallel to the layering, interface waves can be generated only if one of the layers is “pseudoelastic,” i.e., has at least one real wave speed. In this case, the interface waves are generated in the same manner as in the purely elastic case. Such a physical problem would exist, for example, if the incident waves were to travel through a semi-infinite elastic half-space before striking the plane viscoelastic layers. If the incident wave is attenuated in the direction parallel to the layering, interface waves can be generated at specific angles of incidence and specific combinations of material parameters.
Vibration Characteristics of a Submerged Ring-Stiffened Cylindrical Shell of Finite Length
Authors: Paslay P. R. , Tatge R. B. , Wernick R. J. , Walsh E. K. , Muster D. F.
Published: October 2005

An analytical procedure for determining the natural frequencies for a submerged cylinder is presented. The coupling between the shell and acoustic medium is taken into account. An experimental evaluation of this procedure for a particular cylindrical shell is presented. Good agreement is shown between measured and predicted natural frequencies of the cylindrical shell, both in air and submerged in water.
New Method of Evaluating Mutual Coupling of Sources on Nonsimple Bodies
Authors: Mangulis V.
Published: October 2005

Convenient mathematical expressions for mutual coupling coefficients are available only for acoustic or electromagnetic sources on a few simple three-dimensional bodies. It is shown that, for a nonsimple body, the mutual coupling coefficient can be expressed as the same coefficient for a simple body plus a particular correction term, if the geometrical configuration is such that the sources and some of the surrounding surface is common to both the simple and nonsimple bodies. As an example, the mutual coupling coefficients for sources on a finite cylinder are expressed as the coefficients for sources on an infinite cylinder, plus an integral involving the radiation fields of sources on both finite and infinite cylinders.
Symmetrical Normal Modes in a Rankine Vortex
Authors: Sozou C.
Published: October 2005

The normal modes of an inviscid compressible fluid rotating as a Rankine vortex inside a fixed circular cylinder about its axis of symmetry are considered. The computer solution obtained shows that the effect of rotation is to increase the frequency and modify the shape of the normal modes.
Creeping-Wave Theory and Experiment
Authors: McNicholas John V. , Überall H.
Published: October 2005

Recent experimental results that verify the accuracy of computations of target strength using creeping-wave theory has been compared with refinements in the computations. Computations of target strength that use four modes and two circumnavigations reveal that the experimental results and the theoretical results agree almost exactly.
Free Oscillations of Acoustical Resonators and Pressure Effects on Damping and Amplification
Authors: Troke Robert W.
Published: October 2005

The effects of sound-pressure amplitude and static pressure are studied, primarily from experimental text results. Oscillograph records of the transient response of both Helmholtz and pipe resonators are analyzed to determine the damping, decay decrement, and relaxation time of the free oscillations. Damping is determined to be inversely proportional to the static pressure. Damping is found to be a function of amplitude and to decrease as the oscillating pressure amplitude decreases, although at a lesser rate. Since the pressure amplification at resonance is proportional to the reciprocal of the damping, very high amplifications are realized for systems with light damping and low pressure inputs. It is shown that seashells are pipe resonators that respond continuously in the audible range to inaudible inputs. Experimental data and theoretical analyses are used to make a plot of amplification at resonance versus input sound-pressure level.
Ultrasonic Observations of Coarticulation in the Pharynx
Authors: Kelsey C. A. , Woodhouse R. J. , Minifie F. D.
Published: October 2005

Coarticulation effects have been observed in the motion of the lateral pharyngeal wall (LPW) during speech. Pulsed ultrasound was used to measure the displacement of LPW during the trisyllables/aba/, /abi/, /iba/, /ibi/. The extent of vowel-consonant (VC) and consonant vowel (CV) motion was different depending on the other vowel.
Correlation Characteristics and Dimensionality of Speech Spectra
Authors: Li K.-P. , Hughes G. W. , House A. S.
Published: October 2005

Statistical properties of spectral samples derived from the continuous speech of six talkers and summarized by means of covariance-matrix eigenvectors are used to study the dimensionality of the data space. The importance of eliminating low-level samples by means of a fixed threshold is emphasized, and criteria for selecting such a threshold are presented. Measurements of spectral correlations stabilize after about 30 sec of speech, suggesting that short-term examination of a talker's output may prove sufficient to calculate parameters useful in recognition schemes. Some features of the correlation matrix, which are readily displayed via isocorrelation contours, appear to be related to talker characteristics, while others are talker independent. The results suggest that the separation of speech data into gross classes prior to the application of statistical procedures will enhance the performance of processing schemes.
Some Comments on Learning Associated with the Articulation Testing of Mistuned Single-Sideband Links
Authors: Kneen E. J. , Hanson J. V.
Published: October 2005

Learning is shown to be an important consideration in the articulation testing of frequency-shifted (mistuned single-sideband) speech links. Articulation improvements are continuous for up to 100 h of learning, but trade-offs can be made between subject numbers and training time. System comparison testing is discussed as an efficient alternatives scheme.
Underwater Hearing Thresholds in Man as a Function of Water Depth
Authors: Brandt John F. , Hollien Harry
Published: October 2005

Thresholds of human hearing were obtained underwater at depths of 35, 70, and 105 ft. Subjects were six divers experienced in taking underwater hearing-threshold tests by a modified Békésy technique. No significant effect resulting from the depth was noted. Threshold shifts (re air) for the three conditions of underwater hearing were consistent with those previously reported.
Sound-Wave Attenuation through Air Contained in Small Tubes
Authors: Neusen Kenneth F. , Romer I. Carl
Published: October 2005

Sound-wave attenuation measurements were made in air contained in a 0.016-in.-diam tube at 15–30 Hz. The data obtained are at room temperature and at pressure of 1 atm. The measured attenuation coefficients provide substantial verification of the existing small-tube theory of Weston [Proc. Phys. Soc. (London) B66, 695–709 (1953)]. The results suggest a possible method of determining viscosities of gases.
Upper and Lower Bounds for Frequencies of Elastic Arcs
Authors: Chang Tish-Chun , Volterra Enrico
Published: October 2005

Upper and lower bounds of the first four natural frequencies of elastic clamped arcs, which vibrate in a plane perpendicular to that of the initial curvature of the arcs, are obtained by applying to curved beams a method, based on differential operator theory, originally proposed by Lehmann and Maehly. The principal advantage of the method is that it provides, at the same time, the set of upper and lower bounds of natural frequencies of vibrating systems. The center lines of the arcs are in the forms of circles, cycloids, catenaries, and parabolas. Numerical results are presented in tabular form. The upper-bound frequencies so obtained are compared with those obtained by the application of the Rayleigh-Ritz method.
Stress Waves in a Laminated Medium Generated by Transverse Forces
Authors: Voelker L. E. , Achenbach J. D.
Published: October 2005

A laminated medium composed of alternating layers of two homogeneous isotropic elastic solids is suddenly subjected to a spatially uniform distribution of transverse forces, which are applied in a plane normal to the layering. The resulting two-dimensional transient-wave propagation problem is analyzed by means of modal analysis. The normal and shear stresses at the interfaces are expressed as infinite integrals that are integrated numerically for not too large values of time. For larger values of time, the integrals are approximated by the method of stationary phase. The predominant contribution to the interface shear stress comes from the head-of-the-pulse approximation. The normal stress at the interface, which is composed of several contributions, is oscillatory, and the interface bonds may thus be subjected to tensile stresses.
High-Speed Photographic Studies of Ultrasonically Induced Cavitation
Authors: Olson Hilding G. , Hammitt Frederick G.
Published: October 2005

On the basis of photographic studies, it is indicated that the normal collapse mode for a bubble in an ultrasonically induced cavitation field is asymmetrical. In most cases, the bubble involutes into a torus, the direction of the involution being dependent on perturbations of the bubble surface due to pressure gradients, etc. A vortex ring is formed producing a central microjet, the impact of which upon a solid surface is believed to be the predominant damaging mechanism. Three collapse models are hypothesized to explain the existence of the various types and sizes of cavitation bubbles that were observed and to also suggest the mode of a possible damaging collapse. An attempt is made to correlate the known pit damage on an individual specimen to the approximate number of observed bubbles of the type that are believed to be indicative of such a jet impingement on the specimen surface, and it is found that the order of magnitude is correct. Visible evidence of the effect of the shock waves that apparently accompany rebounding bubbles is presented.
Vertical Coherence of Sound Transmitted over a Twenty-Four-Mile Path
Authors: Urick R. J. , Tulko T. J. , Abraham D. D.
Published: October 2005

Continuous-wave signals at 750 and 1500 Hz, transmitted through the deep sea to a range of 24 miles and recorded by various hydrophones of a vertical array, were correlated together in a clipper correlator. The observed correlation coefficients were found to drop rapidly with hydrophone separation distances out to 20 ft but thereafter remained constant out to the maximum distance of 300 ft. Although the transmission path was surface reflected, no clear evidence of a wind-speed dependence of the correlation coefficient was found. The time-delay correlograms observed on the ambient-noise background agreed with those reported in an earlier paper for smaller separation distances.
Transmission of Acoustic Waves through Submerged Viscoelastic Spherical Shells
Authors: Workman George , Hayek Sabih I.
Published: October 2005

A pulsating sphere is located inside a thick concentric viscoelastic spherical shell, which is surrounded by an infinite acoustic medium. The space between the sphere and the shell is filled with the same acoustic medium. A shaped beam of axisymmetric spherical harmonic wave, emitted from the sphere, is transmitted through the shell to the outside medium. The shell is analyzed by use of elastic wave potentials. The emitted acoustic waves are transmitted to the external medium by coupling to the shell through continuity and boundary conditions at the inner and outer surfaces of the shell. The investigation shows that the radiated farfield pressure can be attenuated by as much as 10% through the use of stiff polymers.
Turbulent-Boundary-Layer Pressure Fluctuations and Wavenumber Filtering by Nonuniform Spatial Averaging
Authors: Chase David M.
Published: October 2005

The area-averaged pressure spectrum Q(ω) due to a turbulent boundary layer (TBL) measured by transducers with spatially varying response is treated by the wavenumber approach in the high-frequency, domain ωL/U∞≫2π, where L measures streamwise element size and U∞ denotes asymptotic flow speed. The contribution Q+(ω) to Q(ω) from the convective range of high wavenumbers k1≳ω/U∝, in which the wavenumber spectrum P (K,ω) [where K = (k1,k3)] of TBL pressure has a high ridge, is reduced by a response that varies smoothly over the element and across its periphery. For a circularly symmetric element of radius R0 having a response function and its first n − 1 spatial derivatives continuous and vanishing at the periphery, Q+(ω) is shown, by use of asymptotic Fourier transforms and similarity variables for the TBL pressure, to be reduced relative to the point spectrum by a factor for the ∝ (ωR0/U∞)−2n−3. By contrast, the reduction factor for the low-wavenumber nonconvective contribution Q−(ω), which derives mainly from K≲π/R0, varies, if P (K,ω) is independent of K for most K in this range, as (ωR0/U∝)−2. The coefficient determining the magnitude of Q− relative to Q+ remains uncertain and cannot be reliably inferred from available measurements of the point cross spectrum Γ(ζ,ω). Rectangular elements and effects of shape and orientation are also considered. Various properties of TBL pressure depending mainly on P (K,ω) in the convective range are computed from an approximate P (K,ω) formed to be space/time isotropic in a convected frame and with similarity form characteristic of the universal inner layer.
Atmospheric Correction Factor for Sonic-Boom Pressure Amplitudes
Authors: Pierce Allan D. , Thomas Charles L.
Published: October 2005

An approximate theory is given for the computation of sonic-boom overpressures generated by level rectilinear flight of an aircraft moving at constant supersonic speed in a temperature and wind-stratified atmosphere. The primary result is a relatively simple expression for the atmospheric correction factor KA representing the ratio of predicted shock overpressure to that which would be expected were the atmosphere homogeneous with conditions appropriate to the flight altitude, when the observer is on the ground below the flight path. The derived approximate KA is independent of aircraft parameters and depends only on flight Mach number, altitude of flight, and the atmospheric profiles. The manner of derivation gives KA as a product of two factors: one derived from linear geometrical acoustics, using the eikonal approximation as given by Blokhintzev, and the other representing nonlinear effects whose derivation is based on the premise that an N wave is developed within 10 000 ft of the flight path that propagates along the ray paths derived from geometrical acoustics. Computations of KA illustrating the effects of atmospheric inhomogeneity show qualitative agreement with computations of Hayes, Haefeli, and Kulsrud and show substantial quantitative agreement—although with some discrepancies—with previous computations by Kane and Palmer. A critique of the theory on which the latter computations were based is given, and it is suggested that the cause of the discrepancies could be an inadequate approximation for ray-tube area.
Diffraction of a Plane Acoustic Pulse by a Free Orthogonal Trihedron (Three-Dimensional Corner)
Authors: Shaw Richard P. , Courtine Daniel F.
Published: October 2005

The normal velocity field on arbitrary three-dimensional scattering surfaces struck by a weak acoustic plane wave, is considered. A numerical solution for a right-angle corner (i.e.. three orthogonal edges of infinite length) is found for a step-incident pressure wave, while the wavefront normal is taken to form equal angles with the three orthogonal edges. The scattering obstacle is assumed to have a free surface (i.e., pressure is zero).
Reply to “Comments on ‘Propagating and Standing Sawtooth Waves’” [D. B. Cruikshank, Jr., J. Acoust. Soc. Amer. 46, 1389(L) (1969)]
Authors: Temkin Samuel
Published: October 2005

The assumptions made in the original paper are reiterated and emphasized.
THE ELECTROACOUSTIC HORN—A New High-Intensity Sound Source
Authors: Boucher R. M. G. , Kreuter J.
Published: October 2005

In this paper, the authors describe the various experimental phases that preceded the design of a high-intensity airborne-sound source called the Electroacoustic Horn. This rugged and reliable sound source, which operates within the 10- to 100-kHz range, produces high-intensity emissions (166 dB at the horn mouth) with an electroacoustic efficiency between 20% and 25%.
Combination Tone 2fl−fh in Microphonic Potentials
Authors: Dallos Peter
Published: October 2005

Microphonic potentials were recorded from guinea-pig cochleas with differential electrodes placed into the first and third turns. Distortion components of (n+1)fl−nfh (particularly 2fl−fh) and fh±fl were studied as a function of frequency separation between the primaries and as the function of primary intensities. The conclusion is drawn that all distortion components in the cochlear microphonic behave alike, that is, there is no fundamental distinction between the properties of 2fl−fh and fh−fl. Some properties of the interference phenomenon are also examined in this study. It is suggested on the basis of the present results on distortion in cochlear microphonics and those in the literature treating subjective measures of distortion, that the role of microphonic potentials in the peripheral transduction process should be re-examined.
Frequency Pattern of Residual Masking by Pure Tones Measured on the Békésy Audiometer
Authors: Ehmer Richard H. , Ehmer Barbara J.
Published: October 2005

A Békésy audiogram for a 5-msec tone signal repeated once per second was obtained over the frequency range 100–10 000 Hz. The audiogram was repeated with a 100-msec masking tone preceding the signal by 10 msec. The masking tones were presented at 20 100-dB sensation levels (SLs). The results show that 250 and 500 Hz produce no masking at 20 dB, but the greatest over-all masking, without sharply defined maxima, occurs at higher SLs. Maskers of 1000, 2000, and 4000 Hz produce masking at the 20-dB level. At the low levels, there is a clear peak at the masking frequency; but as the masker level is raised, this peak begins to shift to increasingly higher frequencies, although it never reaches the second harmonic.
Temporary Threshold Shifts Following Pulsed Monaural and Alternate Binaural Exposure
Authors: Guiot J. M.
Published: October 2005

The temporary threshold shifts (TTS) produced by exposure to pulsed monaural and pulsed alternate binaural high-intensity stimuli (105 dB sensation level, 1 kHz) were compared in 7 subjects (6 male, 1 female). All subjects showed greater TTS for monaural exposures than for binaural, except in three cases out of 21 (six experimental conditions). However, monaural and binaural TTS were found to be significantly different (0.01 level) in only one instance of the three paired conditions.
Practice Effects and Signal Detection Indices in an Auditory Vigilance Task
Authors: Hatfield Jimmy L. , Soderquist David R.
Published: October 2005

Performance of nine subjects was investigated over ten 90-min vigilance sessions. Trends in performance over and within sessions were examined in terms of three dependent measures: (a) correct detections, (b) errors of commission, and (c) theory of signal detectability (TSD) indices d′ and β. The results indicate that: (1) TSD accounts for performance over sessions but is inadequate in accounting for within-sessions decrements unless basic tenets of the theory are altered. (2) Performance decreases within sessions for the first 30 min, regardless of practice. (3) Within sessions decrements may be accounted for by assuming either a decrease in the observer's activation level, a distracted mode of observing, or both.
An Unsuccessful Attempt to Determine the Tradability of Interaural Time and Interaural Intensity
Authors: Hershkowitz R. M. , Durlach N. I.
Published: October 2005

Unlike traditional studies of time-intensity trading, in which attention is focused on the trading ratio, an attempt was made to determine the extent to which interaural time delays can be discriminated from interaural intensity differences. The attempt was unsuccessful, however, because of enormous variability in the subjects' responses. It is conjectured that a significant portion of this variability was related to small variations in the fit of the earphones during the course of the experiment.
Application of the TTS Paradigm for Assessing Sound Transmission in the Auditory System during Speech Production
Authors: Karlovich Raymond S. , Luterman Barry F.
Published: October 2005

Ten male and 10 female subjects were exposed to a 100 dB SPL 1000-Hz fatigue stimulus for 3 min. During the exposure time, the subjects repeatedly produced a voiced vowel, a whispered vowel, or performed a nonvoiced articulatory gesture representing a vowel without whispering. Pre- and postexposure thresholds were tracked with a Békésy-type procedure for a stimulus 12 oct above the fatigue frequency. Temporary threshold shift (TTS) in males and females following voiced /ɑ/ and /i/ vowel conditions was significantly less than that observed for corresponding whispered or nonvoiced conditions at each postexposure recovery time measured. The magnitude of these differences ranged from 9 dB at 10 sec to 4 dB at 3 min of recovery. The results strongly indicate that voiced vowel production impedes transmission and hence reduces the energy delivered to the cochlea from a 1000-Hz fatigue stimulis, as evidenced by the reduced TTS magnitudes associated with this condition. Two potential mechanisms are proposed to account for alteration in sound transmission during voiced vowel production. One mechanism involves possible middle-ear muscle contraction, and the other concerns alterations in the normal vibratory mode of the stapes caused by vertical vibrations of the skull during phonation.
Postexposure Responsiveness in the Auditory System. II. Sensitization and Desensitization
Authors: Noffsinger P. Douglas , Olsen Wayne O.
Published: October 2005

Human ears were stimulated by 2-min 20–105 dB sound-pressure level continuous tones, and postexposure thresholds were examined for other tones that were variably related in frequency to the exposure stimuli. Each test tone (250, 1000, and 4000 Hz) was paired with exposure tones of the same, half, and twice the test-tone frequency, as well as with a 50-Hz tone and a tone of considerably higher frequency (4000–10 000 Hz). The postexposure patterns of threshold sensitivity that resulted from such procedures ranged from momentary auditory sensitization to configurations dominated by auditory desensitization. The logic of this sequence of behavior in light of known synaptic activity is discussed.
On Narrow-Band FM Noise as a Masking Noise
Authors: Glaser Edmund M.
Published: October 2005

The use of narrow-band FM noise is suggested for application in experimental studies of masking. It is free of intensity fluctuations and is perceived by a listener to be free of the fluctuations characteristic of narrow-band Gaussian noise. Some of the properties of this noise are discussed, along with a brief description of how it may easily be generated.
Input Generators for Digital Sound Synthesis
Authors: Winham Godfrey , Steiglitz Kenneth
Published: October 2005

A fast method is described for generating a periodic discrete-time signal with harmonics of equal amplitude and a fundamental frequency which is not necessarily an integral fraction of the sampling frequency (as with ordinary pulse generators). Such a signal can be used as input to digital filters for the synthesis of speech and music.
Subjective Study of the Sound-Transmission Class System for Rating Building Partitions
Authors: Clark D. M.
Published: October 2005

The use of single number ratings in describing the acoustic performance of various building elements is very common. Examples of this are the sound-transmission class (STC) of a wall or the impact-noise rating of a floor. In the STC rating method, a transmission-loss (TL) curve of irregular shape is compared to a standard-reference curve. The contribution of various frequency bands depends on the shape of the standard curve and the method of comparison. An experiment has been carried out to determine the relative subjective importance of the various frequency bands and how the change in subjective rating due to irregularities in a TL curve compares with the rating obtained by using the standard curve and fitting rules. Results indicate that the present STC rating system is overconservative in rating changes in a TL curve and that narrow coincidence-type dips are not very important.
Instability of the Motion of a Pulsating Bubble in a Sound Field
Authors: Eller Anthony I. , Crum Lawrence A.
Published: October 2005

This paper describes two related instabilities of spherical bubbles that are set into pulsation by a sound field. One instability is the observed onset of erratic dancing by bubbles that are trapped in a standing wave. This instability occurs when the sound-pressure amplitude exceeds a threshold value, and we measured the threshold for bubbles driven below resonance in water and in isopropyl alcohol. The other instability, which also requires that the sound-pressure amplitude exceed a threshold value, is the theoretically predicted onset of oscillation of the bubble shape. This threshold was calculated for the conditions of the previous experiments by a theory of parametric excitation based on Hill's equation. All results refer to pressure amplitudes less than 0.7 bar and frequencies from 23.6 to 28.3 kHz. From the close agreement of the measured dancing thresholds and the calculated shape-oscillation thresholds, we conclude that the erratic dancing of pulsating bubbles in a sound field is caused by shape oscillations that are parametrically excited by the bubble pulsations.
Absorption and Dispersion of Ultrasonic Waves in Mixtures Containing Volatile Particles
Authors: Goldman Edward B.
Published: October 2005

The absorption and dispersion of ultrasonic waves in a mixture of an inert gas and a vapor with volatile suspended particles of the condensed phase is studied. An equilibrium distribution of particles is found by performing a numerical experiment using equations describing condensation in an initially condensate-free vapor at a given supersaturation. Hydrodynamic equations are developed that include the effects of the interaction of the mixture components with each other and with a polydispersion of suspended particles and the effects of evaporation and condensation. Results are presented for mixtures of air and water vapor containing water droplets.
Distribution of Maxima in the Response of an Oscillator to Random Excitation
Authors: Crandall Stephen H.
Published: October 2005

When a lightly damped linear oscillator responds to stationary wide-band Gaussian excitation, the root-mean-square level and average frequency of the response are relatively insensitive to increases in the bandwidth of the excitation, but the average rate of maxima increases without limit. This phenomenon is interpreted by reexamining the exact distribution of the maxima and by giving a heuristic explanation based on decomposing the response into macroscopic and microscopic components. It is shown that the maxima of the combined response occur in clusters of micromaxima. The distribution of all maxima is estimated by accounting for the number of micromaxima introduced at each macromaximum.
Vibrations of Closed and Open Sandwich Cylindrical Shells Using Refined Theory
Authors: Padovan Joseph , Koplik Bernard
Published: October 2005

The governing dynamic equations are derived for sandwich cylindrical shells including thickness-shear deformation in both the core and face layers. From these equations, solutions are obtained for the free vibrations of both the closed and open configurations for infinite as well as freely supported cylinders. Particular emphasis is placed on the comparison of these results with those based on the face-membrane theory in which the thickness-shear deformation and flexural rigidity of the face layers is suppressed. The importance of including these higher-order effects in the face layers is clearly demonstrated for the lower natural frequencies, even for relatively small ratios of face layer to core thickness. In addition, the effect on the eigenvalue spectrum of varying the opening angle of split sandwich cylindrical shells is investigated.
Exact Theory of Tracking of Moving Underwater Object by Short-Base Navigation System Attached to an Imperfectly Stabilized Moving Ship
Authors: Vaishnav Ramesh N. , Magrab Edward B.
Published: October 2005

The theory of locating a deep submersible by measurement of time delays in arrival of an acoustic pulse from the deep submersible to three hydrophones of a short-base navigational system has been developed in detail. The theory incorporates all the relevant variables such as the translational and rotational positions and velocities of the tracking ship and the variation of acoustic speed with depth. No restrictions have been placed on the relative values of the horizontal and vertical coordinates of the submersible relative to the tracking ship. A numerical example is given to demonstrate the use of the theory and to show the effects of ignoring the motion of the tracking ship and the variation of acoustic speed with oceanic depth.
Scattering of Acoustic Impulses by a Cylinder in Air
Authors: Wright Wayne M.
Published: October 2005

An experiment is described in which A waves from weak sparks in air were scattered from solid cylinders. Creeping waves, which correspond to acoustic energy that propagates along the periphery of a diffracting object, were clearly distiguishable from incident waves and specular reflections.
Forced Vibration of Cylindrically Orthotropic Circular Plates
Authors: Bellini P. X. , Dzialo F. J.
Published: October 2005

Utilizing normal-mode theory, solutions for the forced vibration of cylindrically orthotropic circular plates with rotary inertia are presented for both symmetric and asymmetric motions. Orthogonality conditions and integrals of the square of the eigenfunctions are formulated for the various boundary conditions.