bluuebunny/crossref_metadata_2025 huggingface dataset:
Weber's Law, Power Law, and Internal Noise
Authors: Eijkman E. , Thijssen J. M. , Vendrik A. J. H.
Published: September 2005

Psychophysical experiments concerning the differential sensitivity of the ear for a 1000-cps tone are analyzed. The hypothesis that Weber's law is a case of multiplicative noise was tested. Multiplicative noise exists in systems with fluctuating gain. It can be shown that systems with multiplicative noise displaying Weber's law ΔI/I = CONSTANT possess a power function that relates the relevant neural activity and the stimulus magnitude. The experiments deny, however, a fluctuating gain as the only explanation of Weber's law. The experiments are better described by assuming that observers choose their sensitivity in accordance with the range of stimulus intensities. The internal noise, measured as an equivalent ΔI in the experiment, depends on the range to which the observer has tuned in. A multirange-meter model is discussed, which obeys Weber's law and also shows a restricted class of input-output relations.
Supplementary Observations on the Central Factor in Auditory Fatigue
Authors: Riach W. D. , Sheposh John P.
Published: September 2005

The results from studies concerned with central factor in auditory fatigue have been discursive. The original study of the authors was replicated in order to determine whether the amount and kind of background information made available to the E would affect the outcome. Two groups of E's were employed. One group was given background information that supported only the central factor effect in auditory fatigue, while the other group was presented with all of the previous findings. In general, the data reflected the E's attitude.
Comments on “Masking and Discrimination” [C. E. Bos and E. de Boer, J. Acoust. Sec. Am. 39, 708–715 (1066)]
Authors: Scharf Bertram
Published: September 2005

Previous studies of the critical band of masking clearly indicate that the size of the critical band is about like that measured by Zwicker and others in over half a dozen types of experiments. Amplitude fluctuations of narrow-band noise do make the precise determination of the size of the critical band in masking experiments difficult, but not impossible, as shown by the work of Hamilton.
Acoustic Response of a Circular Receiver to a Circular Source of Different Radius
Authors: Yamada Kazunari , Fujii Yahei
Published: September 2005

This Letter considers an approximation for the acoustic response of a circular receiving aperture to a similarly aligned coaxial circular source. Graphical results for the acoustic response versus aperture separation are given for three cases.
Nonlinear Programming Applied to Linear-Array Design
Authors: Lasdon L. S. , Suchman D. F. , Waren A. D.
Published: September 2005

A generalized approach to the design of practical linear arrays, using recent mathematical optimization techniques, is outlined. The interelement spacing, element amplitudes, and phases are all permitted to vary within specified bounds. The technique can accommodate realistic radiators, since measured directivity patterns can be used in the design. An example is presented that shows that Dolph-Chebychev shading does not provide optimal results or point-source arrays.
Underwater Acoustic Scattering from Arctic Ice
Authors: Mellen R. H.
Published: September 2005

Comparison of the roughness-wavenumber spectrum of an underice sonar profile with that of an equivalent rough surface deduced from reverberation measurements shows levels of the latter to be excessively high. This, together with the apparent disparity between experiment and theory in the dependence of reverberation strength on grazing angle, indicates a need for improvement in the scattering model.
Model Sound Channel with Sinusoidal Rays
Authors: Watson A. G. D.
Published: September 2005

Material is herein reproduced of an Admiralty Research Laboratory note in which it was shown that, if the square of the reciprocal of the sound velocity is a quadratic function of depth (a type of profile due, it is now pointed out, to M. A. Pedersen), then all the ray paths in the neighborhood of the sound-velocity minimum take the form of sine curves. The space and time periods are calculated.
New Methods for Measuring Ultrasonic Attenuation
Authors: Fitch Charles E.
Published: September 2005

Ultrasonic shear-wave attenuation is difficult to measure by the usual bonded transducer methods because of questionable bond integrity and the inability to correct for diffraction effects. New methods for shear-wave measurements were developed, using a liquid buffer and obliquely incident longitudinal waves. Diffraction or beam-spread corrections were made experimentally by using fused quartz samples that have known ultrasonic properties for standards. The methods are also useful for longitudinal-wave measurements. Longitudinal- and shear-wave attenuations were measured in a stainless-steel sample over a frequency range of about 2–15 MHz, using the new methods. Longitudinal attenuation was also measured with pulse-echo methods. All the experimental techniques compared favorably.
Some Deep-Water Sound-Transmission Paths South of Cyprus. Part II: Diffraction Effects
Authors: Baxter Lincoln , Brockhurst Robert
Published: September 2005

Intensity and Fourier spectra of refracted and of bottom-reflected acoustic arrivals in the Mediterranean Sea south of Cyprus at ranges between 16 and 20.4 NM (nautical miles) are presented, together with the most probable sound-velocity profile and the near-surface temperature structure. The arrival structure and relationship between pulse travel time and range indicate that most of the 100- to 800-cps energy contributing to an arrival travels along paths similar to rays, but we find that, below 600 cps, there are frequency differences in the locations of these paths. The discovery of these frequency differences causes us to withdraw the postulate of scattering advanced in our first paper of this title and replace it with one of diffraction. According to Officer [Introduction to the Theory of Sound Transmission, McGraw-Hill Book Co., Inc., New York, 1958), Chap. 2], such differences can be caused by diffraction occurring at depths where the absolute value |λ0(δc′/c)| of the ratio of the fractional change δc′, in the velocity gradient over a wavelength, to the velocity gradient c/λ0 is largest. Our results indicate that the diffraction is observable in the convergence zone if |λ0(δc′/c)| at such depths is approximately 5×10−4 or greater.
Effect of Turbulence Nearfield on a Shielded Transducer
Authors: Heaps H. S.
Published: September 2005

When a transducer of finite size is used to measure the spectral density of a turbulent sound field, the results are dependent on the size of the transducer. If the transducer is separated from the turbulence by a non-turbulent medium, or by an elastic layer, then the recorded pressure is a function of both transducer size and layer thickness. Analysis of the effect of transducer size and separating layer is the purpose of this paper. The theory is developed for computation of attenuation of spectral density as a function of transducer size and distance from the turbulent layer.
Transduction of Boundary-Layer Noise by a Rectangular Panel
Authors: White Pritchard H.
Published: September 2005

The response and consequent sound radiation of a thin rectangular panel excited by convected boundary-layer turbulence has been examined. By taking averages over a frequency band, and including many modes in this average, the detailed characteristics of the system are bypassed and only gross features such as panel modal density, ratio of radiation to total resistance, and the boundary-layer characteristics are of interest. A large portion of the sound power is transmitted in the region of the hydrodynamic coincidence condition. The hydrodynamic coincidence frequency is the most important feature in determining the shape of the transmitted power spectrum, and the power law for the total power radiated. Good agreement between theory, and experiment serve to verify the basic assumptions of the theory.
Deformation and Motion Produced in Isolated Living Cells by Localized Ultrasonic Vibration
Authors: Wilson Walter L. , Wiercinski Floyd J. , Nyborg Wesley L. , Schnitzler R. M. , Sichel F. J.
Published: September 2005

Naturally-isolated living cells were subjected to ultrasonic vibration by means of the tip of a steel needle applied directly to the cell surface or inserted into a drop of a suspension of cells in sea water. The needle was machined into the tip of a stainless-steel cone, and the base of the cone was glued to one end of an electroded and polarized barium titanate hollow cylinder. This composite transducer was driven at its resonant frequency of approximately 85 000 cps. Ultrasound applier to the surfaces of egg cells of marine invertebrates produces rotation, translation, deformation, and fragmentation of the nucleoli; rotation and deformation of the nuclei; acoustic streaming of nucleoplasm and cytoplasm; and deformation of the cellular surface and fragmentation of the cell. Cells and intracellular bodies are often attracted to the sound source as a result of acoustic-radiation pressure, and, especially for whole cells in suspension, this attractive tendency is typically superposed on a tendency of the body to take part in acoustic streaming of the surrounding medium. Some aspects of the motion can be accounted for in terms of presently available theory of nonlinear acoustics. Information on the physical properties of nucleolus, nucleoplasm, and cytoplasm is gained from use of this sonic technique.
On the Application of the EC Model to Interaural jnd's
Authors: Durlach N. I.
Published: September 2005

This paper reports some preliminary results of an attempt to apply the equalization and cancellation (EC) model of binaural unmasking to data on interaural just-noticeable differences (jnd's). The interaural dimensions that are considered are time, amplitude, frequency, and decorrelation.
Membrane Resistance in Endolymphatic Walls of the First Turn of the Guinea-Pig Cochlea
Authors: Johnstone B. M. , Johnstone J. R. , Pugsley I. D.
Published: September 2005

Microelectrodes were inserted into the three scalae of the first turn, and resistance measurements were fitted to a model having six pathways. The six pathways with average resistance values are (1) blood vessels inside the cochlea to the outside of the bulla—1.6 kΩ, (2) blood vessels inside the cochlea to scala tympani—0.6 kΩ, (3) blood vessels inside the cochlea to scala vestibuli—0.8 kΩ, (4) blood vessels inside the cochlea via the stria vascularis to scala media—13 kΩ, (5) scala media direct to scala tympani (organ of Corti)—24 kΩ, (6) scala media direct to scala vestibuli (Reissner's membrane) 46 kΩ. There was no indication of a need to include a direct pathway from scala tympani to scala vestibuli. The “length constant” of scala media in the first turn is about 2.0 mm. The resistance changes due to moderate sound were found to be small, but measurable. Changes of resistance with anoxia showed first a decrease and then an increase in the resistance from scala media to ground.
Masking-Level Differences with Continuous and with Burst Masking Noise
Authors: McFadden Dennis
Published: September 2005

Psychometric functions were obtained for several interaural phase combinations with both continuous and burst masking noise. In the burst conditions, the signal (400 cps, 125 msec) and the wide-band masker (45 dB/cycle) were gated simultaneously; in the continuous conditions, only the signal was gated. Performance on burst N0-S0 was only about 0.5 dB worse than that on continuous N0-S0, but the masking-level differences (MLD's) for N0-Sπ Nπ-S0, N0-Sm, and Nπ-Sm were 4–6 dB smaller with burst than with continuous noise. In an additional experiment, the noise burst (N0) was gated 0, 75, 150, 250, 400, 600, and 1000 msec before the onset of the signal (Sπ). These MLD's increased gradually between 0 and 600 msec and then leveled off at approximately the value obtained with a continuous masker. A single-interval YES-NO procedure was used in these experiments. When two-alternative forced choice was used, the difference between continuous and burst noise was considerably diminished.
Speech Intelligibility for Space Vehicles, Using Nitrogen or Helium as the Inert Gas
Authors: Cooke Julian P. , Beard Sarah E.
Published: September 2005

A laboratory investigation was carried out to help evaluate verbal-communication intelligibility in a man-rated altitude simulator when either helium or nitrogen was added to the oxygen atmosphere. Some eight operators and 37 male subjects were tested with a total of 16 500 random word events at pressures of 5 psia (pounds pressure per square inch, absolute), using 70:30 mixture of O2:He or O2:N2 mixtures and also 100% oxygen at 3.5 psia. An increased lack of intelligibility has been known to occur as gas densities have been reduced. Differences in test scores following the substitution of helium in place of nitrogen at the pressures and mixtures employed resulted in no increased loss of intelligibility other than that associated with the reduced gas density, although some modification of speech can be detected by listeners.
Perception of Segments of English-Spoken Consonant-Vowel Syllables
Authors: Grimm William A.
Published: September 2005

This study was undertaken to determine the effect upon perception of deleting different numbers of 10 msec segments from the initial part of each of a set of consonant-vowel syllables. The scores that were analyzed were proportions of correct identifications of the residual elements by panels of listeners. The outcome was expressed in terms of correct identifications at each duration of the stimuli. Both the correct and error responses were studied to determine the relationship of voicing, manner of release (plosiveness and fricativeness) and place of articulation, to the identification of the stimuli. The results of the experiment indicate that the present procedure is feasible for studying the intelligibility of syllables and their constituent phonemes, and that the voicing manner of release, and place of articulation of the consonant remain evident when the syllable is truncated at the initial end to commence 50 msec before the peak intensity of the vowel of the syllable. The listeners were able to detect correct place of articulation more accurately than either voicing or manner of release as greater amounts of the initial part of a syllable were removed. The responses were related to the threshold of detectability.
Acoustical Interferometer for Velocity and Attenuation Measurements in Liquids over Wide Frequency and Temperature Range
Authors: Leonard R. W. , Seguin H.
Published: September 2005

An acoustical interferometer operating over the frequency range of 1 Mcps up into the gigacycle per second microwave region and from room temperature down to low cryogenic temperatures has been designed, constructed, and tested. The features of the design permit direct and simultaneous measurements of the acoustic wavelength and attenuation to be made. The apparatus is intended for investigation of the liquid state and particularly He3. It appears that a bandwidth of tenthousandfold is feasible.
Interaction of Acoustic Waves with Solid-Gas and Liquid-Vapor Interfaces
Authors: Porter J. W.
Published: September 2005

Adsorption and condensation are presented as mechanisms for the interaction of acoustic waves with solid-gas and liquid-vapor interfaces, respectively. Interface boundary conditions are derived and are used, in turn, to derive equations that describe normal reflection of one-dimensional acoustic waves at infinitely rigid solid-gas and liquid-vapor interfaces. Results show that, as the frequency of the incident wave goes from zero to infinity, the velocity amplitude reflection ratio decreases monotonically from unity to a limiting value that may be as small as 0.42, and the phase shift of the reflected velocity wave goes from zero through a maximum and back to zero. Calculations indicate that significant absorption of the incident wave may begin at frequencies as low as about 1.0 cps (for solid-gas interfaces exhibiting chemisorption and for liquid-vapor interfaces) or as high as about 10 Mcps (for solid-gas interfaces exhibiting monomolecular physical adsorption). The interaction mechanism presented in this paper should prove useful in investigating the effects of acoustic disturbances on (1) heterogeneous chemical reactions between gaseous species adsorbed on a solid or liquid surface and (2) water-vapor condensation small solid or liquid nuclei.
Refined Tube Method for Measuring the Sound Wavelength in Gases—Principles of Operation
Authors: El-Hakeem A. S. , Gaggioli R. A. , Romer I. C.
Published: September 2005

In a recent article [A. S. El-Hakeem, Am. J. Phys. 33, 263 265 (1965)], the senior author described a refined apparatus for measuring the velocity of sound (transmitted through gas confined in a tube) and the method of operation of this apparatus. The present article gives a rigorous explanation of the principles of operation of this new, more accurate device.
Finite-Transform Solution of the Damped, Clamped-Clamped Beam Having Distributed Load and Elastic Support
Authors: Cobble M. H.
Published: September 2005

The beam equation for a uniform-cross-section, damped, elastically supported clamped-clamped beam is solved for very general conditions of arbitrary initial, boundary, and distributed-load conditions. The solution is based on the properties of a Hermitian operator and its orthogonal basis vectors, with which an arbitrary vector can be expanded.
Axisymmetric Response of a Closed Spherical Shell to a Nearly Uniform Radial Impulse
Authors: McIvor Ivor K. , Sonstegard David A.
Published: September 2005

When a closed spherical shell is suddenly enveloped by a uniform impulse, the response is a purely radial motion of each shell element. If the impulse is slightly nonuniform, this membrane “breathing mode” may be dynamically unstable due to the interaction of the membrane stress with flexural curvature. The linear solution for axisymmetric motion divides into two sets of modes. One set, the membrane modes, is essentially extensional; the second set, the composite modes, is neither purely extensional nor purely inextensional. The linear response to an arbitrary radial velocity distribution indicates that breathing mode stability may be considered with respect to perturbations exciting only composite modes. Using this result the nonlinear study shows that a cyclic energy exchange may occur between the breathing mode and rather high-order composite modes. The ensuing deflections and stresses may be considerably in excess of those determined by consideration of the breathing mode only.
Finite Radial Oscillations of a Spinning Thick-Walled Cylinder
Authors: Nowinski J. L. , Wang S. D.
Published: September 2005

This paper treats large-amplitude radial oscillations of a perfectly elastic infinite cylinder made of an isotropic incompressible material. The oscillation follow a sudden setting of the cylinder into a uniform spinning motion about its longitudinal axis. By using Knowles's approach, the oscillations are analyzed for materials with essentially arbitrary constitutive equations. General conditions are found for the motions of the cylinder to be periodic. The results are specialized to three classes of rubberlike materials: Mooney-Rivlin, Neo-Hookean, and Ishihara et al.-Zahorski. Graphs are given (for some experimentally corroborated values of the elastic constants) for the frequency of oscillations and the maximum displacement of the inner radius of the tube versus the angular speed of the spin.
Reply to “Comments on ‘Influence of Sound upon Local Heat Transfer from a Cylinder’ ” [R. M. Fand, J. Acoust. Soc. Am. 38, 370–372 (L) (1965)]
Authors: Richardson P. D.
Published: September 2005

The comments of Fand are discussed, and an outline of some recent investigations is given. It is found that the comments are incorrectly founded and that the leading point involves an issue in semantics rather than physical facts. It is not necessary to alter the conclusions of the original paper.
Prompting versus Confirmation in the Discrimination and Identification of Two Auditory Dimensions
Authors: Aiken Edwin G.
Published: September 2005

Two training procedures were compared for their efficiency in improving the identification and discrimination of acoustic stimuli. One procedure (prompting) involved presentation of the correct answer before the presentation of the stimulus or stimuli. The other procedure (confirmation) involved presentation of the correct answer after the stimulus or stimuli had been judged. Results of the first experiment indicated that confirmation was significantly superior to prompting in training pitch discrimination. Experiment 2 results revealed no difference between the procedures in improving either two-alternative pitch or loudness identifition. In neither experiment did the difficulty of the perceptual task interact with the training procedures. It is suggested that the nature of the perceptual judgment required and degree of response uncertainty are both variables influencing the outcomes of comparisons of prompting and confirmation in perceptual learning.
Perceptual Independence and Recognition of Two-Dimensional Auditory Stimuli
Authors: Corcoran D. W. J.
Published: September 2005

The experiment was designed to test the fit of a simple independence model to two-dimensional auditory stimuli. Subjects (six in number) were required to name four stimuli, which were either high in pitch (1250 cps) or low (1000 cps) and either amplitude modulated twice per second at 60% or unmodulated. After attaining perfect identification the stimuli were presented in white noise (signal-to-noise ratio of −17.5 dB) and subjects attempted to name them as before. The resulting stimulus-response matrix was matched against a theoretical matrix derived from an independence theory. The pitch dimension was well described by independence, but modulation was not so well described. It was concluded that, although independence may not describe the underlying perceptual mechanism, it is nevertheless satisfactory as an over-all predictor.
Development of Auditory Narrow-Band Frequency Contours
Authors: Elliott Lois L.
Published: September 2005

Four experiments were performed to explore the hypothesis that time is required for the auditory system to develop steady-state contours corresponding to stimulation by a narrow band of frequencies. Four additive and interacting phenomena appear necessary to explain the observed results: on and off effects, temporal integration of acoustic energy, temporal persistence of the excitation pattern, and time-dependent organization of frequency contours.
Frequency Selectivity of the Ear in Forward Masking
Authors: Glattke Theodore J. , Small Arnold M.
Published: September 2005

In a stimulus paradigm in which the masker terminates prior to the signal presentation (forward masking), threshold shifts as a function signal frequency closely resemble those observed for simultaneous masking. The purpose of the present study was to determine if a “critical band” could be identified for forward masking. Two-component masker (primary) stimuli centered in the regions of 800 and 3200 Hz were presented to 10 listeners. The amount of forward masking was measured as a function of signal frequency, while the frequency separation of the sinusoids comprising the primary stimulus was varied systematically. Previously reported simultaneous-masking data suggested that a critical bandwidth could be defined as the frequency separation of masker components coincident with a change in the shape of the function relating amount of masking to signal frequency. For the conditions employed in the present study, no changes in this function were observed even at wide separation of the primary components.
Human Performance in Low-Signal-Probability Tasks
Authors: Lucas Patrick A.
Published: September 2005

An extension of the theory of signal detection (TSD) to psychophysical tasks involving low-probability signals and free-response data is developed and evaluated. Emphasis is placed on tasks for which the observer is asynchronous—that is, the observer cannot perform optimally by making independent decisions on nonoverlapping intervals of time. A mathematical model of asynchronous observation in a class of temporally unstructured tasks with Neyman-Pearson solutions for optimal fixed-response rate is used to describe detection performance by human observers. Data from an experiment show (1) a conservative fixed-response rate, (2) a constant hit rate, and (3) interresponse distributions for false alarms with a general exponential shape showing periodic modes. Detection efficiency in the temporally unstructured task was approximately 110 of alerted-detection efficiency for two observers and 12 of alerted-detection efficiency for a third observer. Points on the obtained receiver-operating-characteristic (ROC) curve are fit better by an inefficient asynchronous observer than by synchronous power-law observers. A post hoc analysis of the effect of training showed an effect for distribution of responses in time but showed no effect of an improvement in memory for the signal. It is concluded that highly trained observers detecting important signals show constant efficiency over observation periods of 30–45 min. The TSD psychophysical model of asynchronous observation seems to be an adequate description of human performance in the low-probability free-response task used in this study.
Effect of Two Interaural Phase Conditions for Binaural Exposures on Threshold Shift
Authors: Melnick William
Published: September 2005

Monaural temporary threshold shift (TTS) was measured following 2 min of exposure under three conditions of presentation, monaural, binaurally in phase, and binaurally out of phase by 180°. When listeners were exposed to 500 and 750 Hz at 120 and 110 dB, respectively, TTS at test signals of 750 and 1000 Hz was greater for monaural than for binaural exposure conditions, and no phase effect was noted. For an exposure-test signal combination of 4000 and 6000 Hz, the binaural-monaural difference was eliminated but there was a significant phase effect for the two binaural exposure conditions. More TTS occurred when the exposure signal was 180° out of phase. No difference was observed among the exposure conditions for TTS at 750 Hz following exposure to a 400–600-Hz band of noise at 120 dB. The “frying-noise” tinnitus that follows high-level tonal exposure was reported to disappear at 70–80 sec postexposure for both binaural and monaural exposure.
Model of the Displacement between Opposing Points on the Tectorial Membrane and Reticular Lamina
Authors: Rhode William S. , Geisler C. Daniel
Published: September 2005

A quantitative model of the relative motion between the tectorial membrane and reticular lamina of the mammalian cochlea is presented. The model is proposed for the stapes side of the region of maximum deflection during sinusoidal excitation. Based on familiar concepts, the model assumes that basilar membrane deflection causes a sliding motion between the tectorial membrane and the reticular lamina. Equations for the motion between opposing points on these two structures are derived in terms of various cochlear dimensions and of the basilar-membrane displacement. Average values of these dimensions, obtained from eight cat ears, were used to achieve numerical answers.
Reliability of Auditory Threshold Determinations Using a Circumaural-Earphone Assembly
Authors: Atherley G. R. C. , Hempstock T. I. , Lord P. , Walker J. G.
Published: September 2005

In a previous paper, a circumaural earphone that was intended to improve the reliability of auditory threshold measurements was described. This paper is concerned with its evaluation using the results from tests on 100 subjects. The test-retest variances at 1,3,6, and 8 kHz for the circumaural and supra-aural assemblies are compared. At 6 and 8 kHz, the “within-ear” variances for the circumaural assembly are 4.8 and 8.8 dB2, respectively, and are significantly smaller than the corresponding values for the supra-aural device. At 1 and 3 kHz, the reliability is substantially unchanged. It would seem, therefore, that the use of the circumaural earphone will increase the accuracy of auditory-threshold determinations high frequencies.
External-Ear Replica for Acoustical Testing
Authors: Bauer Benjamin B. , Rosenheck Allan J. , Abbagnaro Louis A.
Published: September 2005

As part of the development of an acoustical manikin, an artificial ear was designed to simulate the mechanical and acoustical properties of the external ear, up to and including the impedance of the eardrum. The sensing element is a B&K 4132 electrostatic microphone terminating a simulated ear canal with an acoustical impedance-matching network that, combined with the microphone, furnishes the eardrum impedance. The canal proper has dimensions approximating those of the real ear and is placed inside a skull of polyester-impregnated fiberglass, provided with a plastisol pinna of realistic dimensions and texture. The head is mounted on a fiber torso. The new artificial ear is suitable for testing all types of receivers and ear enclosures under realistic conditions. The inner portion of the artificial ear is made of reproducible metallic components, making it suitable for consideration as an artificial-ear standard.
Acoustical Velocity Amplifier Study
Authors: MacVicar-Whelan P. J.
Published: September 2005

Free-free mode-resonator solutions for plane longitudinal waves in a bar, where the particle velocity is of the form u(z) = A cosk1z+B sink1z, have been investigated. In particular, gains of 10 accompanied by a shape factor of 3 have been sought. Such gains are obtainable, but shape factors only as large as 2 were found.
Absorption Cross Section of a Pipe Organ Due to Resonant Vibration of the Pipe Walls
Authors: Benade A. H.
Published: September 2005

The sound absorption by a rank of organ pipes from a sound field arises chiefly from air-column resonance losses plus boundary-layer dissipation at the external surfaces of the pipes. These processes have been discussed elsewhere [A. H. Benade, J. Acoust. Soc. Am. 38, 780–798 (1965) and 41, 32–38 (1967)]. The pipe walls themselves can vibrate when driven by the sound field, so that there is a further absorption of energy. The present report shows (on the basis of measured elastic and damping constants of pipe metal) that the wall-vibration resonance-absorption cross section for a complete rank of cylindrical organ pipes is negligible, being less than 1 cm2 at 62 Hz, falling to less than 0.05 cm2 at 2000 Hz. For elliptical pipes, the absorption can be a hundred fold larger, but it is still negligible as compared with the other absorption processes. It is also shown that the reradiation due to wall vibrations is so small as to justify the assumption, on which an earlier calculation of external surface absorption was based, that the pipes scatter as though they are essentially rigid.
Changes in the Vibrational Napier (Relaxation) Time of Methane-Water-Vapor Mixtures
Authors: Monkewicz Alan A.
Published: September 2005

Using a modified Hubbard low-pressure acoustic interferometer, the velocity dispersion of methane-water-vapor mixtures was measured as a function of (f/p). The napier time of the mixture was determined from these measurements. From this it was possible to obtain values of the napier time of the mixtures as a function of the mole percent of water vapor present. These values show a nonlinear dependence on the percent mole fraction. The results were subjected to an analysis similar to that of Tuesday and Boudart, an analysis that is based on two postulates: a “resonance” between methane and water vapor and rapid de-excitation of water vapor by itself. Numerical solution of the resulting equation kTτP−K10+(K20−K10)X+K30X[K50+(K40−K50)X(K03+K50)+(K40−K03−K50)X] yielded a quadratic dependence of the napier time on the mole fraction of water vapor similar to the case of oxygen-water mixture. Reaction rates for the five possible reactions in a binary gas mixture were obtained. Since these reaction rates are the reciprocals of the napier times, the collisions numbers were also obtained. When the collision numbers obtained are compared with those of other investigators, the agreement is found to be very good, particularly for water vapor.
Damage-Risk Criterion for the Impulsive Noise of “Toys”
Authors: Gjaevenes Kjell
Published: September 2005

Based on physical and medical data, the damage-risk criterion (DRC) for the impulsive noise from crackers and popguns is discussed, and a DRC of 155 dB peak pressure is proposed.
Underwater Sound-Pulse Distortion by a Converging Lens
Authors: Mellen Robert H. , Browning David G.
Published: September 2005

Measurements show that a symmetric underwater sound pulse is distorted by a converging lens so that the waveform becomes antisymmetric at the focus and polarity reversed a few pulse lengths beyond. The use of linear time transforms to describe pulse distortion along rays involving caustics and the inclusion of finite-amplitude effects are discussed.
Radial Propagation of Axial Shear Waves in Nonhomogeneous Elastic Media
Authors: Chou Pei Chi , Gordon Paul F.
Published: September 2005

The radial propagation of axial shear waves in nonhomogeneous elastic media is solved by both the Laplace transform technique and the method of characteristics. Closed-form solutions for certain cases of non-homogeneity are obtained by the former technique. Numerical integration of the characteristic equations yields results that are in good agreement with those obtained by Laplace transforms. For certain problems, the method of characteristics yields solutions unattainable by Laplace transforms.
Normal-Mode Vibrations of Model of Centrosymmetric Cubic Crystal
Authors: Hoppmann W. H. , Kunukkasseril V. X.
Published: September 2005

Free-vibration experiments were conducted on two- and three-dimensional models of a centrosymmetric cubic crystal. Frequencies and mode shapes were determined. Also, some theoretical calculations were made of the frequencies and mode shapes, using previously measured elastic constants. Several classes of vibrations were identified.
Response and Damping of a Simple Beam with Tuned Dampers
Authors: Jones David I. G.
Published: September 2005

An approximate analysis of the response in the fundamental mode of any simple single-span beam with tuned viscoelastic dampers attached at discrete locations is presented. A harmonic loading with arbitrary spatial distribution is assumed. It is shown that, to a good degree of approximation, a single expression can be made to represent the response in the fundamental mode of a beam with any boundary conditions, provided that certain effective mass and stiffness parameters are defined for the beam/damper configuration. Comparisons are made with an exact theory, subject to the limitations of the Euler-Bernoulli beam equation, of the response and damping of a cantilever beam having an isolated tuned viscoelastic damper and an isolated harmonically varying load at the free end. Good agreement between the exact and approximate theories is demonstrated. Conclusions are drawn concerning the equivalent damping introduced into the simple structure by the tuned dampers and the damper natural frequency needed for optimal damping.
Random Vibration of Multidegree-of-Freedom Hysteretic Structures
Authors: Karnopp Dean , Brown Richard N.
Published: September 2005

A method is developed for analyzing vibratory systems that may exhibit yielding or other hysteretic behavior under broad-band random forcing. The techniques rely on a balance of power supplied by the forcing and dissipated in hysteretic effects. Since the application area involves the practical case of lightly damped structures, a transformation into normal-mode coordinates is used even for systems exhibiting nonlinear damping. One- and two-degree of-freedom examples are considered in detail and general concepts are given where possible. Limitations inherent in the method are discussed.
Oscillations of a Circular Membrane on a Nonlinear Elastic Foundation
Authors: Mack Lawrence R. , McQueary Charles E.
Published: September 2005

The solution for periodic axisymmetric oscillations of a taut circular membrane on a Duffing-type nonlinear elastic foundation is obtained through the second order, the zeroth order being the linearized solution. For positive values of the nonlinear foundation constant, the membrane configuration is seen to be flatter near the center and steeper near the edge than the linearized configuration. The nonlinear effects on the frequency of oscillation are also portrayed. A small-divisor difficulty is encountered for discrete “critical” values of the tension parameter; however, for tensions near a critical tension, modifications of the general procedure yield solutions which are bounded.
Asymptotic Phase Velocities of Axisymmetric Waves in Composite Rods
Authors: Mengi Y. , McNiven H. D.
Published: September 2005

In this study, it is found that all axisymmetric waves traveling in very long composite rods do so at the speed of certain classical waves as the wavelength approaches zero. The velocities are those of Rayleigh waves in the casing, Stoneley waves at the interface, and the shear velocities in each of the core and casing materials. The number and nature of waves that exist asymptotically depend on the properties of the rod. It is found that all composite, elastic rods can be divided into four classes and that in each class there is a different combination of the asymptotic classical phase velocities.
Ambient Sea Noise in the Deep and Shallow Ocean
Authors: Arase Elizabeth M. , Arase T.
Published: September 2005

Ambient sea noise was measured simultaneously with two identical hydrophones in the frequency range 22–715 Hz. One was located on a shallow bank in about 30 f (fathoms) of water, the other at a depth of about 900 f, both near the ocean bottom. Windspeed measurements were taken simultaneously. Autocorrelations of the ambient-noise levels and windspeed, as well as cross correlations between hydrophones and between the individual hydrophone levels and windspeed, are presented. At low frequency, the shallow-hydrophone ambient noise shows greater correlation with windspeed than the deep one. At higher frequencies, the correlation with windspeed is similar for both receivers. The sea noise at the deep hydrophone was found to be greater than at the shallow one. This difference is a maximum at about 50 Hz, decreasing at both lower and higher frequency.
Reverberation under Arctic Sea-Ice
Authors: Brown J. R. , Milne A. R.
Published: September 2005

Backscattering strengths were obtained from polar pack ice in the Beaufort Sea during April 1965. The ice surface in the experimental area consisted of 10%–15% of pressure ridges separating random patches of 1 yr ice. The results cover a frequency range of 40 to 10240 Hz and a grazing-angle range of 5°–85°. Comparison with earlier results obtained with the same equipment and methods but limited to frequencies of between 1280 and 10 240 Hz indicates a strong relationship between surface roughness and scattering strength. The variation with frequency of scattering strength is small over the 8-oct range examined. However, at grazing angles below 20° and frequencies below the 320–640-Hz band, scattering strength falls with decreasing frequency.
Effects of Pressure Gradients on Turbulent-Boundary-Layer Wall-Pressure Fluctuations
Authors: Schloemer Howard H.
Published: September 2005

Spectral density, magnitude of the normalized longitudinal and lateral cross-spectral-density functions, and convection-velocity ratio as a function of longitudinal separation and frequency of wall-pressure fluctuations were measured with small flush-mounted transducers. These measurements were accomplished in both mild adverse and mild favorable pressure gradients in a low-turbulence subsonic wind tunnel. To establish a basis of comparison, similar measurements were made for the zero pressure gradient, and agreement with published measurements was excellent. The effect of an adverse pressure gradient on the nondimensionalized spectral density was an increase in the low-frequency content without influencing the high-frequency portion appreciably; a sharp decrease in the high-frequency portion was observed for the favorable pressure gradient. At similar nondimensionalized longitudinal separations and frequencies, the convection velocity ratio was higher in the favorable and lower in the adverse pressure gradients. The longitudinal decay of a particular eddy was more rapid in the adverse and slower in the favorable pressure gradients. No differences were found in the lateral cross-spectral density for the different pressure gradients.
Computer Recognition of Connected Speech
Authors: Reddy D. R.
Published: September 2005

A system for obtaining a phonemic transcription from a connected speech sample entered into the computer by a microphone and an analog-to-digital converter is described. A feature-extraction program divides the speech utterance into segments approximately corresponding to phonemes, determines pitch periods of those segments where pitch analysis is appropriate, and computes a list of parameters for each segment. A classification program assigns a phoneme-group label (vowellike segment, fricativelike segment, etc.) to each segment, determines whether a segment should be classified as a phoneme or whether it represents a phoneme boundary between two phonemes, and then assigns phoneme label to each segment that is not rejected as being a phoneme boundary. About 30 utterances of 1–2 sec duration were analyzed using the above programs on an interconnected IBM 7090-PDP1 system. Correct identification of many vowel and consonantal phonemes was achieved for a single speaker using the same speech material that was used for developing the recognition procedure. The time for analysis of each utterance was about 40 times real time.
Time-Domain Bandwidth-Compression System
Authors: Stover W. R.
Published: September 2005

A voice narrow-band-transmission system (VONAX) is described. The concepts upon which the system is based are discussed, and an experimental system is described. The system operates in a digital transmission mode at data rates of 9600, 4800, 2400, or 1200 bits/sec. In the present form, the experimental device is being used as a laboratory, research tool in the general area of speech-processing research.
Excitation and Measurement of Acoustic Ion Waves
Authors: Sessler G. M.
Published: September 2005

Measurements of the phase velocity and the attenuation constant of acoustic ion waves in weakly ionized gases in the frequency range from 0.1 to 6 MHz are described. The experiments were performed in continuous rf discharges having ion plasma frequencies of the order of 1 MHz. A beam of plane ion wares was excited and received by grids with diameters much greater than the wavelengths. At frequencies well below the ion plasma frequency, the phase velocity is frequency-independent and approximately given by the Tonks-Langmuir speed; the predicted dependence on ion mass is verified. The attenuation in this frequency range is primarily due to ion-neutral collisions. At higher frequencies, the phase velocity increases slightly, whereas the attenuation per wavelength falls somewhat off. These results can be explained by assuming non-Maxwellian velocity distribution of the ion gas. The measured phase velocity and attenuation were found to be independent of the geometrical dimensions of the grids, independent of the signal voltage applied to the excitation grid, and not influenced by drifts of the charged particles.
Ducted Acoustic Gravity Waves in a Nearly Isothermal Atmosphere
Authors: Daniels Gerald M.
Published: September 2005

The propagation of acoustic gravity waves is analyzed in atmospheres that have vertical profiles of sound speed squared of the form c2(z) = c2(∞)±Δc2e−2/l, where c2(∞)≫Δc2>0, and both c2(∞) and Δc2 are constant. Ducted wave dispersion relations are obtained from the requirements that the earth's surface act as a rigid boundary to the atmospheric oscillations and that the integral of the acoustic energy density over an infinite vertical column be finite. Ducted modes corresponding to the Lamb wave in an isothermal atmosphere and a surface wave in an incompressible medium are obtained for both signs in the above profiles. In addition, for the profile with the negative sign, an infinite number of closely spaced internal gravity and acoustic modes is shown to exist.
Echoes from Spherical Shells in Air
Authors: Hickling Robert
Published: September 2005

Calculated results show that the elastic reaction caused by sound waves incident on a solid spherical shell in air can have a noticeable effect on the resultant echoes. The effect appears to be strongest for thin shells made of light material. For polyethylene, for example, the effect is found to exist for all thicknesses of the shell. It is suggested that the elastic response of an acoustic target might be used by bats in echolocation.
Axisymmetric Vibrations of a Solid Elastic Cylinder Encased in a Rigid Container
Authors: Hutchinson James R.
Published: September 2005

This paper describes the effects of end boundary conditions on the vibrational characteristics of solid propellent rocket motors. Previously, in the literature, solutions have been based on those obtained for an infinitely long cylinder. These solutions yield only certain sets of possible end boundary conditions for a finite cylinder, but not those considered here (i.e., fixed on all boundaries). The present approach consists of choosing a series of functions with unknown coefficients. Each term satisfies the governing differential equation and the boundary conditions on the axial displacement. The boundary conditions on the radial displacement are approximated by an orthogonalization procedure. This method yields an eigenvalue matrix the coefficients of which are transcendental functions of the frequency. The accuracy of the final solution depends on how well the radial displacement boundary conditions are satisfied. It is found that the procedure converges, and that sufficient accuracy is achieved, through the use of 20 terms in the series. The range of application of the simpler method, based on an infinite cylinder, is discussed by comparing results obtained from both methods.
Mobility of a Long Cylindrical Shell
Authors: Palladino J. L. , Neubert V. H.
Published: September 2005

Results of an experimental and theoretical study of the mobility of a long, moderately thick-walled, pipe-like, cylindrical shell are reported. Experimental data for mobility are compared, over a wide frequency range not previously investigated, with analytical predictions based on thin-shell theory. Existing solutions for free vibrations of thin shells are extended to predict vibration response to a point force that varies sinusoidally with time, based on a normal-mode series solution. Practical convergence of the series is of special interest. The long, pipelike shell was chosen to make this convergence problem more severe since the resonances in some frequency ranges are very closely spaced. For most of the study, the ends of the experimental shell were free to move laterally, but the end cross section was restrained to maintain a circularshape; consequently, the shell was treated as free for the 1 = n or beam modes, and freely supported for the n = 2 or lobar modes. Some resonant frequencies are also included for the shell with completely free ends. Boundary conditions for the free-free shell are discussed.
Vibration of A Rigid Circular Disk on an Infinite Isotropic Elastic Plate
Authors: Paul H. S.
Published: September 2005

The solution for a rigid circular disk vibrating vertically on an infinite elastic thick plate is investigated. Two cases are analyzed in which (a) the rigid disk is vibrating on an infinite plate that rests on a rigid immovable base, and (b) the rigid disk is vibrating on one surface of the plate while the other surface is kept free. The dual integral equations technique of Lebedev and Ufliand is utilized to solve the mixed boundary-value problems. Numerical results are presented to illustrate the method.