bluuebunny/crossref_metadata_2025 huggingface dataset:
Formulation of Wave Propagation in Infinite Media by Normal Coordinates with an Application to Diffraction
Authors: Biot M. A. , Tolstoy I.
Published: September 2005

In the theories of acoustical and electromagnetic vibrations of enclosures, as well as in field theory and electrodynamics, one quite commonly uses normal modes as generalized coordinates in Hilbert space. Here the method is extended to unlimited or partially limited mechanical media, essentially by first solving the problem for an enclosure and going to a limit while expanding all or some of the boundaries to infinity. This leads to a very useful technique, of somewhat more generality than analogous procedures used in field theory. Thus it is applicable to all non-dissipative mechanical continua, for any boundary conditions, irrespective of the order or number of differential operators describing the continua and regardless of whether the coordinate systems are separable or not.

A general orthonormality condition valid in all such cases together with the necessary rules for dealing with divergent normalizing coefficients are easily obtained by limiting procedures. An equally general formulation for arbitrary sources is obtained from the principle of virtual work. The method is illustrated by simple examples, for the case of a point source representing the instantaneous injection of a unit volume, i.e., an idealized, infinitely rapid, explosion. It is shown that in the problem of diffraction by a rigid wedge or corner one is led very quickly to an explicit solution in closed form, involving elementary functions only. Some physical implications of this solution are mentioned briefly. The advantages of the normal coordinates method are discussed when thus used in propagation or diffraction problems in unlimited or partially limited mechanical continua. Obvious advantages are its generality, its flexibility in dealing with arbitrary sources, and the fact that it leads directly to the progressive transient solution.
Measurement of the Acoustic Impedance of a Viscoelastic Fluid in a Circular Tube
Authors: Thurston George B.
Published: September 2005

The results of measurement of the acoustic impedance of some viscoelastic fluids in circular tubes are presented. The fluids studied include water, petroleum oil, glycerol, silicone fluid, milling yellow solution, and agar solution, the last three showing elastic effects. One of these elastic effects is the changing of the acoustic reactance from the inertance type to the compliance type. Measured results are presented for frequencies from 3 cps to 300 cps and for tubes having radii in the range 0.0172 cm to 0.354 cm. Methods are presented for determination of the complex coefficient of shear viscosity from the acoustic impedance properties and examples are given.
Comments on “Mechanical Mechanism of Destructive Effects of Sound on Tissue”
Authors: Dunn Floyd
Published: September 2005

A recently proposed theory to explain some of the nonthermal, non-cavitation effects of intense high-frequency sound on living tissue is discussed in the light of more recent experiments. It is concluded that the assumption of the theory that the observed effects are caused by uni-directional forces (proportional to the square of the particle velocity amplitude) of the acoustic field which create sufficiently great displacements in structural members of the tissue to produce elastic failure, is not supported by experimental results.
Response of a Single-Degree-of-Freedom Isolator to a Random Disturbance
Authors: Kaufman S. , Lapinski W. L. , McCaa R. C.
Published: September 2005

A method is presented for computing acceleration, deflection, and velocity response of a damped, single-degree-of-freedom isolator, subject to a random disturbance between finite frequency limits. A closed-form solution is obtained for the case where the power spectral density is constant within any given bandwidth. The results are plotted in such a manner that the responses to a variable power spectral density function can readily be computed.
Sound-Speed Measurements Utilizing the Bathyscaph TRIESTE
Authors: Mackenzie K. V.
Published: September 2005

Sound-speed measurements and corresponding oceanographic data were obtained aboard the bathyscaph TRIESTE to a depth of 5760 m. Subsequent measurements were made in shallow northern waters by lowering the velocimeters and Nansen bottles from a surface ship. Near-surface measurements agree with the laboratory data of either Del Grosso or Wilson. One set of the deeper measurements aboard the bathyscaph indicates a general agreement with Wilson, but the measured values were less than values computed by Wilson's equations and this difference increased with depth. The acceleration of gravity was measured at a depth of 2286 m and the increase with depth was in rough agreement with the equation in H. V. Sverdrup's The Oceans (Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1949).
Effect of Pressure between Tool Tip and Workpiece on the Rate of Ultrasonic Machining in Ketos Tool Steel
Authors: Goetze Dieter
Published: September 2005

Data are presented for the ultrasonic machining rate in Ketos tool steel obtained by using rectangular tool tips having different perimeters and circular tool tips having different radii. It is shown that the pressure rather than the force maintained between the tool tip and the workpiece is pertinent in the ultrasonic machining process, and that the ratio C/A of the tool tip perimeter C to the tool tip area A is of importance. It is also shown that for rectangular and circular tool tips a critical machining rate V0 and a critical pressure P0 exists, the values of which are related to the ratio C/A by the two simple expressions V0 = 2ξνdM(C/A) and P0 = L(C/A), where 2ξ and ν are the peak to peak amplitude and the frequency of vibration respectively, d is the abrasive particle diameter, and M and L are parameters independent of 2ξ, ν, d, C or A. On the basis of the above two equations a phenomenological expression is derived which for circular and rectangular tool tips relates the machining rate in general to the pressure in general.
Dynamic Magnetostrictive Properties of Ni-Fe Alloys
Authors: Davis C. M. , Helms H. H. , Ferebee S. F.
Published: September 2005

The dynamic magnetostrictive properties of Ni-Fe alloys containing from 35% to 67.5% nickel were investigated to determine their suitability for use in electromechanical transducers. The material, in the form of toroids made from ring laminations, was evaluated by the motional impedance method. Annealing temperatures were varied from 600°C to 1220°C, and the effect of various annealing techniques was investigated. Measured values of the electromechanical coupling coefficient, the reversible permeability, the dynamic magnetostrictive constant, and other parameters are given.

The electromechanical coupling coefficient for alloys containing from 40% to 52.5% nickel was greater than 0.31. A maximum value of 0.37 was found for the 40% nickel alloy. The product of the magnetostrictive constant and the reversible permeability for the above range of alloys was greater than 95×104 (dynes/oersted-cm2) and reached a maximum value of approximately 130×104 for the alloy containing approximately 40% nickel.
Reflection, Transmission, and Amplification of Sound by a Moving Medium
Authors: Ribner Herbert S.
Published: September 2005

The reflection and transmission process is analyzed for plane sound waves originating in air at rest and impinging obliquely on a plane interface with a moving stream. Use of a moving reference frame provides transformation to an equivalent aerodynamic problem of flows past a wavy wall—the rippled interface. The angles of incidence, reflection, and refraction are identified with the Mach angles. The angular relations and the amplitude relations (coefficients of reflection and transmission) are evaluated in closed form. In a graph three zones can be distinguished the plane of angle of incidence v. Mach number of the moving medium: ordinary reflection and transmission, total reflection, and amplified reflection and transmission. Included are three loci of infinite reflection: i.e., serf-excited waves. The energy balance is examined, and the source of amplification is concluded to be the energy of the moving stream. In appendices the results are generalized (1) for the case of two moving media and (2) for differing density and speed of sound in the two media.
Variation of Elastic Constants and Static Strains with Hydrostatic Pressure: A Method for Calculation from Ultrasonic Measurements
Authors: Cook Richard K.
Published: September 2005

The elastic constants and static strains of a solid subjected to large hydrostatic pressures can be deduced from measurements of resonant frequencies (or transit times) for ultrasonic waves in specimens of suitable crystallographic orientations. The pressure changes the specimen's size, shape, and density as well as the elastic constants, and all of the effects influence the resonant frequencies. An algorithm for separating out the effects due to variations in elastic constants from the effects due to static strains is presented and applied to cubic crystals and hexagonal crystals, these structures being of immediate interest to investigators concerned with the properties of metals. The results apply also to isotropic and transversely isotropic solids. The only measurements needed while the specimen is under hydrostatic pressure are resonant frequencies (or transit times). Also required are the size and density at zero pressure, or the elastic constants at zero pressure.
Acoustical Characteristics of Oscillating Jet-Edge Systems in Water
Authors: Brackenridge J. Bruce , Nyborg Wesley L.
Published: September 2005

Observations have been made on the sound radiated by a self-excited underwater jet-edge system, in which a flat jet of water impinges on the sharp edge of a wedge or blade. Comparison made between the sound (edge tones) generated when a rigid wedge is used, and that when a fixed-free vibrating blade is employed. A characteristic kind of “resonance” is found, similar to that reported by others for analogous systems in air.
Three-Element Stagger-Tuned Transducer Array for Broadband Operation
Authors: Hueter T. F. , Currie W. E.
Published: September 2005

This investigation was conducted to determine the feasibility of a compact, lightweight, multi-element broadband transducer. Three bender-type elements with proportionately spaced resonant frequencies were assembled in a cluster. The assembly proved capable of radiating from 1.75–2.70 kc with not more than ±1.5 db power variation, if the elements were properly spaced. This investigation demonstrated that low Q devices can be constructed from a combination of stagger-tuned high Q elements providing that proper orientation and spacing are observed.
Monitoring Task in Speech Communication
Authors: Egan James P.
Published: September 2005

Some communication situations involve several noisy channels, and only certain ones of these carry relevant information to a given communication operator. The operator must receive and identify a restricted number of different messages, and he must ignore others. The performance of the listener in this situation will depend both on the discriminability of the messages and on the listener's criterion for accepting his response as correct or rejecting it as incorrect. The present paper gives a quantitative description of the monitor's behavior in terms of the operating characteristic and the articulation-criterion function. The results of two experiments are reported. In one of these, the confusion matrices for the various sets of messages were also determined.
On Vowel Duration in English
Authors: House Arthur S.
Published: September 2005

Average durations of 12 vowels of American English measured in bisyllabic nonsense utterances are reported. The vowels occurred in 14 symmetrical consonantal environments and the utterances were produced by three male talkers. The consonant environments consisted of the voiced and voiceless versions of three stop, one affricate, and three fricative consonant articulations. Four determinants of the characteristic durations of stressed vowels are identified and discussed. The hypothesis is advanced that the primary lengthening of vowels in English—that found in tense vowels and in vowels before voiced constants—is a part of the phonology of the language and is learned by speakers of the language, and that the secondary lengthening of vowels in English—that found in open vowels and in vowels before fricative constants—is a function of the articulatory process itself.
Korotkoff Sounds in Humans
Authors: Wallace John D. , Lewis David H. , Khalil Sami Abou
Published: September 2005

Direct monitoring of Korotkoff sounds from the brachial artex with vascular pressure, cuff pressure, and external sounds has been carried out. Recording of the internal sounds suggests a discrepancy between direct and indirect blood pressure measurement. Examples of spectrograms of the Korotkoff sounds near diastolic pressure are presented.
On the Realization of a Linear Graph Given Its Algebraic Specification
Authors: Auslander L. , Trent H. M.
Published: September 2005

The following problem is discussed in this paper. Given an algebraic specification of an oriented linear graph in the form of a branch-mesh or branch-node matrix on any arbitrary basis, how does one proceed systematically to construct the graph? This rather basic problem has been considered by other authors and a few procedures have been described in the literature. On closer examination the problem is not simply one of finding any old procedure that will work but rather a question of finding an efficient procedure in terms of the time required by an analyst to carry through the computation. A new procedure is described which is believed to be quite efficient. This procedure is simple since matrix manipulations are limited primarily to the deletion of rows and columns and the other main manipulation is that of freehand drawing.

The procedure is based upon the Decomposition Theorem published earlier and involves the notion of dividing a large graph into a sequence of small ones. A reassembly process then yields the desired result.
Simultaneous Two-Tone Pitch Discrimination
Authors: Thurlow W. R. , Bernstein S.
Published: September 2005

The frequency separation between two simultaneously sounding tones necessary to give perception of two pitches has been investigated. Frequency levels of 200, 1000, 4000, 6000, and 10 000 cps were used. For the two-ear condition (where one tone was led to one ear, the other tone to the other ear), no striking differences were found between results at sensation levels of 10, 30, and 50 db. When both tones were led to the same ear, results tended to approach the two-ear situation when masking and interaction effects were minimized.

The relation of the two-ear results to localization is discussed. Finally special phenomena are described which arise when two low frequencies, related by simple multiples, are used in the two-ear situation.
Optimum Frequencies for Active Sonar Detection
Authors: Stewart J. L. , Westerfield E. C. , Brandon M. K.
Published: September 2005

The method of determination of the optimum frequencies for active sonar without knowledge of the absolute values of the sonar-set parameters, but only of their frequency dependence, appears to have been originated by J. W. Horton in about 1945 and is to be found in his recent text. This theory has been simplified and extended to include search rate,time-processing gain, and the ratio of echo-to-noise-plus-reverberation. The inclusion of these new factors only slightly modifies the results obtained by maximizing echo-to-noise ratio alone because of the dominant effect of the frequency dependent exponential attenuation term in the transmission loss. Because of the octave or greater width of the maxima and the lack of precision in the knowledge of the frequency dependencies, the optimum frequencies should be looked on only as broad regions. For longer-range and hence lower-frequency active sonata operating at their optimum frequencies the energy of the pulse required per unit area or volume searched increases rapidly with the design range to a high exponent for the cases considered. This corollary is probably of little practical significance since the cost of operating power is usually small compared to other costs.
Microbubble Persistence in Fresh Water
Authors: Turner W. R.
Published: September 2005

Preliminary research confirms that microbubbles become stabilized in a body of water and persist for long periods of time in contradiction of classical theory. The evidence was obtained by generating bubbles at the bottom of a water tank and then measuring the decay of ultrasonic attenuation as bubbles of various sizes rose to the surface. Comparison of experimental and classical decay curves disclosed persistence that appeared to be a function of the solid particle content of the water and indicated that bubbles may stabilize at sizes as large as 30 μ radius in water of high particulate content. In waters of low particulate content the decay of attenuation lasted over 100 hr.

Substantial persistent abnormal attenuation was detected in all fresh tap water measured, amounting to a minimum 44% over that of distilled water (at 5.125 Mc) and is believed to be caused by stabilized bubble nuclei somewhat less than 0.8 μ in size. An interesting discovery was that attenuation rose in an uncovered test basin but fell in a covered basin, indicating that microbubbles may enter water on dust particles.

A hypothesis presented to explain the persistence effect suggests that solid particles collect on the bubble surface, forming a compressed wall capable of supporting the excess pressure necessary to halt gas diffusion. Other hypotheses explore the mechanism by which dust particles may carry air globules below the water surface, and the dynamics of microbubble populations.
Critical Band Width in Loudness Summation
Authors: Zwicker E. , Flottorp G. , Stevens S. S.
Published: September 2005

The concept of the critical band, or Frequenzgruppe, is shown to apply to loudness summation. When the spacing between a group of pure tones is increased, the loudness remains constant until a critical point is reached, after which the loudness increases. The same effect occurs when the width of a band of noise of constant SPL is made larger. The critical band width at which loudness summation begins to depend on the spread of energy is approximately the same as the critical band width determined previously by methods involving thresholds, masking, and phase. The critical band as measured directly by these three methods (plus the method of loudness summation) is about two-and-a-half times as wide as the critical band derived from the assumptions made by Fletcher, but its dependence on frequency is approximately the same. The relation of the critical band to other functions is noted.
Lagrangian One-Dimensional Equations of Hydrodynamics for a Viscous, Thermally Conducting Fluid
Authors: Blackstock David T.
Published: September 2005

The exact Lagrangian formulation for one dimensional, rectilinear motion of a viscous, thermally conducting fluid is derived from the corresponding Eulerian formulation. Applicable results are compared with the Lagrangian equations given by Fay (1931) and Lindsay (1960).
Research on the Acoustic Air-Jet Generator: A New Development
Authors: Brun E. , Boucher R. M. G.
Published: September 2005

The structure and operation of the Hartmann air-jet ultrasonic generator has been reviewed critically, and modifications are described which substantially increase the efficiency and available power output of the original device. Experimental results are presented in confirmation of the theoretical analysis.

An important part of the development has been the employment of a secondary resonator and projecting exponential horn. A novel design using a large number of whistles in a single horn (Multiwhistle R.B.) is described. This unit has a wide frequency and power range, and has been employed in France for agglomeration of aerosols, ultrasonic drying, fog dispersal, and other interesting applications.
Shock Spectrum as a Criterion of Severity of Shock Impulses
Authors: Morrow Charles T.
Published: September 2005

Shock impulses have not as yet yielded to any practical method of spectral analysis that would permit convenient exact calculation of all the peak internal responses of hardware subject to such accelerations, and also permit comparison of shock severities by inspection. The shock spectrum with a few supplementary techniques, provides adequate insight into the responses of a one degree of freedom resonator. As an indication of the responses of a system with several coupled degrees of freedom, a second-order shock spectrum is defined. An oscillatory constituent of the spectrum is also defined in such a way as to be applicable to any order of spectrum. Investigation of these two concepts leads to the conclusion that if the first-order shock spectrum technique is to be used as a basis for comparison of the severity of a laboratory test shock with that of a service shock, spectra should be plotted for both positive and negative directions. Moreover, when feasible, such spectra should ordinarily be plotted as distinct curves for the intervals during and after the test shock, and the oscillatory constituent for the interval during the shock should be estimated.
On the Width of Critical Bands
Authors: Swets John A. , Green David M. , Tanner Wilson P.
Published: September 2005

A different technique of analysis is applied to the experiment suggested by Harvey Fletcher for measuring the width of the critical band. This experiment determines the ability of noise bands of different widths to mask a pure tone centered in the band. The analysis considers two filters in series, one outside and one inside the observer. The width of the second filter (the critical band) can be estimated from measurements of the reduction in the noise power at the detector which is effected by the pair of filters. The width of the critical band is estimated under four different assumptions about the shape of the band. The results provide a context for discussing the reasons that may underlie the widely varying estimates of the critical bandwidth which have been obtained in previous studies.
Concerning the Form of the Loudness Function
Authors: Stevens S. S.
Published: September 2005

In order to examine certain possible irregularities in the loudness function, the method of adjustment was used to halve and double the loudness of a 1000-cy tone at the levels 30, 60, 90, and 120 db re 0.0002 μbar. The results tend partially to confirm some of the irregularities found by Robinson. The results also indicate that a reasonable approximation to the loudness function is the rule that a change of 10 db corresponds to a loudness ratio of 2:1. This means that loudness grows approximately as a power function of intensity. It is noted that the power function also describes the relation between psychological magnitude and stimulus magnitude on a dozen other perceptual continua.
Average Responses to Clicks Recorded from the Human Scalp
Authors: Geisler C. Daniel , Rosenblith Walter A.
Published: September 2005

The use of a method of electronic averaging in the detection of electrical responses from human subjects is briefly described. The correlation of such data with psychophysical data from the same subject is discussed.
Factoral Analysis of the Delayed Speech Feedback Phenomenon
Authors: Butler Robert A. , Galloway F. Thomas
Published: September 2005

Two experiments, employing a total of 388 subjects, were conducted to further study factors influencing performance on the delayed speech feedback task. The rate of presenting reading material, the intensity, and length of delay of speech feedback served as independent variables. A linear relation was found between performance on the feedback task and intensity of the delayed signal. There was an interaction between intensity and delay time of the speech feedback, clearly demonstrating that various delays are differentially effective only at high intensity levels. That the role of delay is more than a simple interference factor produced by background noise was also demonstrated.
Word Intelligibility as a Function of Time Compression
Authors: Fairbanks Grant , Kodman Frank
Published: September 2005

An experiment is described in which words were automatically compressed in duration and presented to observers for identification. The effects of time compression and of time sampling are assessed, and compared with those of periodic interruption. The results of an analogous nonauditory study of the effects of phonemic sampling are presented.
Helmholtz's Aversion to Tempered Tuning Experimentally Shown to be a Neurological Problem
Authors: Meyer Max F.
Published: September 2005

Experiments show that the brain of people of ordinary musical endowment, when unsophisticated, enables them to esthetically appreciate melodies that are even more mistuned than the equally tempered scale.
Relation of Nuclear Spin-Lattice Relaxation to Ultrasonic Viscous Relaxation in Liquids
Authors: Litovitz Theodore A.
Published: September 2005

The limitations in the use of the Debye relation for relating the nuclear relaxation time, T1, to the shear viscosity, η, are emphasized. The possible connection between the correlation time, τc, and the shear and volume relaxation times as measured by ultrasonics is investigated. It is shown that τc and the average shear relaxation time in glycerol are very close in value. Furthermore, the value of τc found for water is very close to the volume relaxation time as calculated from ultrasonic absorption data. By assuming that τc is proportional to the shear relaxation time a reasonable explanation of the pressure dependence of T1 is obtained.
Remarks on Bobber's Paper: “Interference vs Frequency in Measurements in a Shallow Lake”
Authors: Stulken E. J.
Published: September 2005

Interference waves resulting from an impulsive source show the same characteristics in a favorable water layer as those described by Bobber for sine wave sources. Recent work in prospecting geophysics on dealing with this phenomenon may apply to problems of underwater sound as well.
Response of Internally Damped Beams on Vibrating Supports
Authors: Ehlers F. Edward
Published: September 2005

The classical Euler beam equation is modified by introducing a hysteresis damping term which is proportional to the strain but which is in phase with the strain velocity. General solutions are obtained for the cantilever, clamped, and pin-supported beams whose supports are moved by a prescribed function of time. For sinusoidal vibration of the support, the analysis of a cantilever beam is compared with experiment and with the corresponding solution in which the damping is proportional to the rate of strain as formulated by Sezawa. The hysteresis type damping gives results closer to the experimental values than Sezawa's method. The shear stress and displacement in a cantilever beam whose support falls on an elastic platform are investigated. The analysis is applicable to clamped and pin-supported beams by substituting the appropriate resonant frequencies and eigenfunctions. Simple formulas for dynamic load factors at the resonant frequencies are found by comparing the maximum displacement or shear stress of the beam under sinusoidal vibration of its supports with the corresponding displacement or shear stress for a static loading under a centrifugal acceleration of the same amplitude as the sinusoidal acceleration. Rice's theory of random noise is applied to the response of the beam on a support vibrating in a random manner.
Effect of Heat Radiation on Sound Propagation in Gases
Authors: Smith P. W.
Published: September 2005

The effect is re-examined after considerable modification of the classical analysis. Account is taken of the fact that a gas radiates energy of given electromagnetic wavelength in proportion to its corresponding coefficient of absorption, which is a strongly varying function of wavelength with a number of isolated peaks. No restriction is placed upon the value of the electromagnetic absorption per acoustic wavelength. The results indicate that the acoustic attenuation, which generally increases with decreasing frequency, will show a plateau or very flat peak near those frequencies at which one of the peaks of electromagnetic absorption reaches value of 4π nepers per acoustic wavelength. An upper bound for the effect shows that dispersion and attenuation will be negligible at all frequencies for gases at atmospheric pressure and room temperature, but may become significant in rarified gases or at elevated temperatures.
Long-Range Shallow-Water Bottom Reverberation
Authors: Mackenzie K. V.
Published: September 2005

A theory is presented which enables the computation to be made of 200- to 3000-cps bottom reverberation returning from very great ranges in shallow water. Typical computed curves are presented for reverberation level vs range/water depth. Computed curves are presented for scattering strength vs range/water depth. These later curves are presented for both the isospeed and negative sound-speed gradient cases.
Ultrasonic Atomization of Liquids
Authors: Lang Robert J.
Published: September 2005

An experimental study was made of the mechanism by which the ultrasonic vibration of liquid surfaces causes atomization.

At exciting frequencies in the range of 10 to 800 kc, uniform patterns of crossed capillary waves were found on the liquid surface when atomization occurred. The number-median diameter of the particles produced was found to be a constant fraction, 0.34, of the capillary wavelength; the capillary wavelength is calculable by Kelvin's equation using the exciting frequency and properties of the fluid being atomized.

The evidence is strong that the mechanism of ultrasonic atomization involves the rupture of capillary surface waves and the subsequent ejection of the wave peaks from the surface as particles.
On Frequency Response Curves in Rooms. Comparison of Experimental, Theoretical, and Monte Carlo Results for the Average Frequency Spacing between Maxima
Authors: Schroeder M. R. , Kuttruff K. H.
Published: September 2005

The average frequency spacing 〈Δfmax〉 between adjacent maxima of the frequency response curve between two points in a room is determined by experiment, theory, and Monte Carlo computation. In earlier papers it had been shown that, above a certain critical frequency, 〈Δfmax〉 is reciprocally related to reverberation time and not dependent on other room characteristics—disproving a belief that 〈Δfmax〉 is a useful measure of the acoustical quality of rooms. Theory predicts 〈Δfmax〉 = 3.91/T60, where T60 is the reverberation time. Monte Carlo computation gives 3.90/T60. Measurements in two very different rooms using a vacuum tube voltmeter for reading the sound pressure are in good agreement with these predictions. Measurements with a logarithmic level recorder give, as in earlier investigations, much larger values. The discrepancy cannot be explained by the level recorder's 0.5-db quantization. This paper shows that: (1) The Monte Carlo method is a useful tool for solving complex problems in room acoustics. (2) Level recorder measurements of frequency (or space) irregularities of rooms must be taken with several grains of salt.
Constant-Ratio Rule for Confusion Matrices in Speech Communication
Authors: Clarke Frank R.
Published: September 2005

Three experiments are reported which give support to an empirical rule which may be used for predicting the entries in a closed confusion matrix for any subset of items drawn from a master set of items with a known confusion matrix. This rule, the constant-ratio rule, states that the ratio between any two entries in a row of a submatrix is equal to the ratio between the corresponding two entries in the master matrix. For this statement of the rule it is assumed that the only variables which differ systematically in obtaining the two matrices are the different sets of messages and the allowable responses. This is an empirical rule which was formulated after examination of three 6×6 master matrices for CV's (consonant-vowel syllables) and six 3×3 submatrices. Two more experiments using monosyllables and digits were then conducted to test further the rule. Although no direct experimental evidence is reported, the use of the constant-ratio rule for predicting a master matrix given some of its possible submatrices is discussed.
Optimum Acoustic Criteria of Concert Halls for the Performance of Classical Music
Authors: Winckel Fritz W.
Published: September 2005

The known criteria of room acoustics are not sufficient to characterize the quality of concert halls. To obtain more specific information on the acoustic qualities of concert halls, the author went on tour with the Cleveland Orchestra, making measurements in 15 concert halls. These measurements revealed that the dynamic range of performed music and also the tempo are different in the several halls. The dynamic range depends on the noise level of the room and the state of sound diffusion. The tempo of music is at a maximum in concert halls which have optimum reverberation time and diffusion.
A Mapping of Binaural Click Lateralizations
Authors: Guttman Newman
Published: September 2005

This experiment principally attempted to map the movements of lateralized auditory images associated with 1-pps unfiltered clicks heard at two intensity levels and over a wide range of interaural time and intensity differences. With sensation level at 16 db in both ears, lateralization effects were heard for interaural time differences as large as ±15 msec. With 16 db SL in one ear, the minimum level in the other ear producing effects was −6 db, the effect usually being a “bulge” of the image in the audible ear occurring within ±2 msec interaural time difference. Approximately the same time-difference limits were found, respectively, for 36 db in both ears and 36 db in one ear paired with the minimally effectual −2 db in the other ear. The time-difference limits within which fusion was “complete” (only one image heard) ranged from 3–7 msec, louder ear leading, to 3 msec, louder ear lagging. It is suggested that the results set a bound on the contribution of direct binaural correlation to the precedence-effect phenomenon.
Vibrations of Ferroelectric Cylindrical Shells with Transverse Isotropy. I. Radially Polarized Case
Authors: Haskins J. F. , Walsh J. L.
Published: September 2005

Expressions for the coupled mechanical vibrations and electrical admittance of ferroelectric tubes having transverse isotropy are derived and the results supported with experimental data. Coupled modes in radially polarized barium titanate tubes are examined as a function of length to radius ratio. A frequency-dependent expression is given for the admittance in terms of electromechanical coupling, capacitance, and tube length. Results permit close prediction of resonant frequencies. An optimum length to radius ratio of 2.9 is indicated for maximum electromechanical coupling with the gravest radial mode in a radially polarized tube.
Magnitude Estimations of Pitch
Authors: Beck Jacob , Shaw William A.
Published: September 2005

Using the method of magnitude estimation, the experiments reported investigated the effect of the frequency of the standard upon the pitch functions for piano tones and randomly chosen pure tones. The pitch functions obtained are found to agree in an important respect with each other and with the function previously reported for pure tones chosen to correspond to notes on the musical scale. When the frequency of the standard was the lowest tone presented, the magnitude estimations yielded a function similar to the revised mel scale, and when the standard was a frequency nearer the middle of the series, the magnitude estimations yielded a steeper function closer to the original mel scale. Data are also presented showing that the numerical value of the standard can affect the magnitude estimation function. These results indicate that response biases relating to the frequency and numerical value of the standard may be expected to influence the pitch function determined by magnitude estimations. The nature and effect of these biases are discussed. It is concluded that care is required in viewing magnitude estimation judgments as reflecting a simple correspondence between frequency and the sensation of pitch.
Acoustical Radiation Pressure Due to Incident Plane Progressive Waves on Spherical Objects
Authors: Maidanik G.
Published: September 2005

The expression for the force exerted on a scattering sphere by a plane progressive wave is computed by making use of the general formulation derived by P. J. Westervelt. The expression is general in the sense that it allows for complex refractive index and variation of the relative effective densities of the sphere to that of the surrounding medium. The numerical calculations are confined to the case of “hard” and “soft” spheres only.
Effect of a Reflecting Plane on the Power Output of Sound Sources
Authors: Ingard Uno , Lamb George L.
Published: September 2005

The presence of a reflecting plane boundary will affect the power output of a sound source located above it. This effect may be expressed as a “power amplification factor” which has been calculated for a number of elementary sound sources (monopole, dipole and longitudinal quadrupole) as a function of the distance between the plane and the source. Special attention has been given to evaluation of the source height yielding minimum power output and to the ratio between the maximum and minimum power radiated.
Demonstration of a Speech Processing System Consisting of a Speech Analyzer, Translator, Typer, and Synthesizer
Authors: Olson Harry F. , Belar Herbert , de Sobrino Ricardo
Published: September 2005

A public demonstration of a rudimentary speech processing system consisting of a speech analyzer, language translator, type decoder, and speech synthesizer was given at the Meeting of the Acoustical Society of America in New York, May 23–26, 1962. Each word spoken into the microphone was analyzed, converted to a syllable code, transmitted as a syllable code, synthesized to speech, or converted to the typed page either in the same language or other languages. The two language inputs were English and French, the synthesized speech outputs were English, French, and Spanish and the typed outputs were English, French, German, and Spanish.
Application of Linear Programming to the Design of Polygonal Delay Lines
Authors: James Paul N.
Published: September 2005

A method is presented for increasing the aperture of solid, polygonal delay lines based on the method of linear programming. If it is assumed that there is no spreading of energy so that the acoustic beam may be defined by two parallel lines, the radii of the polygon can be computed which result in the maximum value of the aperture (the distance between the parallel lines) for fixed angles, subject to the constraints of the problem. Small variations in the angles which lead to a further increase the aperture can also be computed by linear programming. In addition, the method can be applied if the beam is assumed to spread in a linear fashion.
On the Inadequacy of the Method of Beats as a Measure of Aural Harmonics
Authors: Chocholle R. , Legouix J. P.
Published: September 2005

The use of the method of beats would bring us to the conclusion that the aural harmonics are very important; but this does not agree with other experiments. The perception of beats in these conditions is essentially the result of interferences between the primary and the auxiliary tones; hence, the inadequacy of the method.
Optical Effects of Ultrasonic Waves Producing Phase and Amplitude Modulation
Authors: Hargrove L. E.
Published: September 2005

A theory is developed for the diffraction of light by ultrasonic waves of sufficiently high frequency, large amplitude, and/or large beamwidth that the emerging light wavefront is significantly amplitude modulated in addition to the phase modulation considered in the Raman-Nath approach. The ultrasonic beam is considered to consist of N adjacent sections and the final diffraction spectrum to result from N successive diffractions. The diffraction orders emerging from a given section are considered to be sources for further diffraction by the next section. Only phase modulation of the separate plane waves (diffraction orders) is considered within a section. Refraction of light is not considered as such; it is characterized by successive redistribution of light in the diffraction orders. Numerical results are obtained by iterations using an electronic computer. These results are compared with measurements.
About the Sensation of Beats between Two Tones Whose Frequencies are Nearly in a Simple Ratio
Authors: Chocholle R. , Legouix J. P.
Published: September 2005

Beats are usually described as appearing between two tones whose frequencies are nearly in ratio 1 to 1; but the sensation of beats appears also when two tones, whose frequencies are approaching other simple ratios, are emitted simultaneously.
Vibrations of Point-Driven Cylindrical Shells
Authors: Heckl Manfred
Published: September 2005

By using some approximations it is possible to get fairly simple approximate formulas for the number of resonance frequencies and for the point impedance of thin cylinders. Measurements of the resonance frequencies and of the number of resonances within a certain frequency range confirm the theoretical results.
Infinite Array of Circular Pistons on a Rigid Plane Baffle
Authors: Mangulis V.
Published: September 2005

The performance of an array is affected by the interaction of the array elements; this interaction is expressed as a radiation impedance. The radiation impedance for a circular piston in an infinite planar array is calculated as a function of distance between elements and the angle to which the array is steered.
Influence of Shock-Machine Loading on Shock Spectra
Authors: Luhrs H. N. , Spence H. R.
Published: September 2005

The influence of loading of a test item on a rigid shock-Machine platform was investigated to determine whether any peaks or notches are introduced into the acceleration shock spectrum which would cause excessive over or under testing at various frequencies. The results showed that the shock spectrum for a terminal peak saw tooth pulse is quite insensitive to shock-machine loading. The very low frequency end (below 100 cps for a 6-msec pulse) is most influenced, whereas the higher frequencies are virtually not influenced at all. The results also showed that even for a very high loading condition the primary spectrum is in all cases less severe than the residual spectrum.

Curves have been generated to depict both the primary and the residual spectrum for various resonators to shock platform mass ratios, for the case of a terminal peak saw-tooth pulse. This particular shock pulse is of interest since the resulting shock spectrum satisfies the requirements of a number of U.S. Air Force missile electronic equipment specifications.
Torsional Vibration of Beams Having Rectangular Cross Sections
Authors: Vet Maarten
Published: September 2005

An elastic energy method is presented for finding the fundamental torsional vibration frequency of solid rectangular beams without boundary constraints. A Rayleigh-Ritz method is employed, and the results, which were calculated on an IBM 650 computer, are shown. Also illustrated is the effect a change in the Poisson's ratio of the beam material has on the fundamental frequency. A comparison is made with results of torsional vibration tests performed at the National Bureau of Standards. This comparison indicates that the analytical method employed gives fairly accurate results.
In Search of the Bone-Conduction Threshold in a Free Sound Field
Authors: Zwislocki J.
Published: September 2005

Several investigators have attempted indirect determination of the bone-conduction threshold in a free sound field. It has recently become possible to attenuate sound transmitted through the auditory meatus to a level below that of a sound reaching the ear through other pathways. By varying the properties of sound-attenuating devices, and with the help of resonance phenomena, it could be shown that the remaining hearing was actually controlled by body conduction, if not more specifically by bone conduction. According to these measurements, the “minimum audible field” for body conduction (MAFB) exceeds 80 db re 0.0002 dyne/cm2 at low frequencies and decreases gradually to a minimum of about 45 to 50 db between 1500 and 2000 cps. For higher frequencies it increases somewhat again. The difference between body conduction and air conduction seems to be maximal in the vicinity of 500 cps—approximately 65 db. At frequencies around 100 cps the difference is of the order of 50 db. This difference holds also for the frequency range between 2000 and 6000 cps. Between 1500 and 2000 cps the difference is only about 45 db.
Theory of Time-Averaged-Product Arrays
Authors: Berman A. , Clay C. S.
Published: September 2005

The mathematical analysis of the directional characteristics of linear additive arrays is given in a polynomial representation. The result of multiplying and taking a time average of the outputs of several detectors also has directional characteristics that may be expressed as polynomials. It is shown that the same directional characteristics may be obtained from multiplicative arrays having a small number of detectors as with an additive array with a large number of elements. The length of the multiplicative array is about half the length of the additive array having the same directional characteristics.
Self-Reciprocity Transducer Calibration in a Solid Medium
Authors: White R. M.
Published: September 2005

The applicability of the self-reciprocity technique to the calibration of a reversible compressional wave transducer in a solid medium is demonstrated, and a method is described of correcting for the electrical loading by the source signal generator of the transducer being calibrated.
Use of Four-Pole Parameters in Vibration Calculations
Authors: Molloy C. T.
Published: September 2005

Linear elastic systems which have a single input point and a single output point can be characterized by a pair of simple linear equations, namely, Finput=α11Foutput+α12Voutput,Vinput=α21Foutput+α22Voutput, where the F's are forces, the V's are velocities, and the α's are the four-pole parameters for the system. The use of four-pole parameters permits combinations of mechanical elements to be handled as a single entity, and, as the parameters belong only to the elastic system for which they are defined, they do not depend upon what precedes that particular system or follows it in a mechanical network. This permits the statement of results in a rather general form. These parameters have been used for many years in the analysis of electrical circuits, and it is the purpose of this paper to show their utility in the field of mechanical vibrations. In particular, the four-pole parameters for the basic mechanical elements of mass, spring, and resistance, will be obtained. Also, a description of mechanical sources will be given. The rules for the connection of four poles and a method of experimentally measuring four-pole parameters will be presented. A few specific problems illustrating the use of four poles will be set forth, namely: a generalized vibration isolation problem, the response of an elastically mounted mass on an electrodynamic shake table, shock excitation analysis, and some distributed parameter systems (i.e., helical springs and rubber in shear).