bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature Dependence of Dynamic Magnetostrictive Properties in Nickel-Cobalt-Chromium Alloys
Authors: Clark C. A. , Mason J. J.
Published: September 2005

The variation of electromechanical coupling coefficient and resonant frequency with temperature, over the range −60° to +60°C, has been determined for nickel and certain alloys of nickel with cobalt and chromium. The results indicate that some of the alloys possess almost temperature-in-variant properties near room temperature. This effect is explained qualitatively in terms of the magnetocrystalline anisotropy energy and magnetostriction of the alloys.
Ultrasonic Velocity and Absorption in Dry Carbon Dioxide at Moderate Pressures, II
Authors: Henderson M. C. , Peselnick L.
Published: September 2005

Further measurements have been made with a recording acoustic interferometer [J. Acoust. Soc. Am. 29, 181(A) (1957)] of the velocity and absorption of 1 and 3 mc/sec ultrasound at temperatures from 19° to 51°C—i.e., including the region of the critical point—and at pressures up to 500 atmospheres. The relaxation time τ remains inversely proportional to the density of the gas or liquid in both phases and shifts with temperature in the expected manner. Unlike the velocity, the measured absorption coefficient per wavelength acts as though it were continuous across the density gap between liquid and vapor phases. Practically all the absorption in the region of the experiment is a consequence of thermal relaxation of the vibrational modes of the molecule. (Work supported by the Office of Naval Research.)
Comments on “On the Dependence of Directivity Patterns on the Distance from the Emitter,” by J. Pachner
Authors: Mohammed A. , Narayanan M. S.
Published: September 2005

Pachner's analysis on the determination of directivity patterns from near-field measurements has been generalized. A necessary and sufficient condition for the validity of Pachner's results has been derived.
Relationship of New Sound Materials to Compositional Techniques in Music
Authors: Luening Otto
Published: September 2005

A summary of Ferruccio Busoni's theories as set forth in his writings, particularly in “A New Aesthetic of Music”; Arnold Schoenberg's use of the term “Tone Colour Melody”; a description of the term “sonority forms” and the use of these in musical compositions; the use of electronic musical instruments in the early part of the 20th century; the use of these instruments in the period from 1920 to 1945 with reference to works by composers Honegger, Hindemith, Varèse, Levides, and others; the works of the Parisian “Musique Concrete” group, the Cologne group, the Milan and New York groups, using these resources now, will be given.
Physical Principles of Contemporary Sonics
Authors: Hunt Frederick V.
Published: September 2005

Contemporary sonics embraces a wide variety of applications of sound waves for the acquisition of information and for the production of useful effects in the medium or at its boundaries. Information gathering capitalizes chiefly on linear, small-signal effects such as the time of flight or the direction of return of pulses, the absorption or speed of sound in the medium, or some effect of the medium on a vibrating source. The useful gross effects of sound waves are associated with the production of high local velocities, shear rates, or accelerations, and with the second-order, nonlinear effects that lead to localized streaming, cavitation, and the reduction of concentration gradients by breakdown of laminar or sublaminar boundary layers. A catalog of these effects, with some attention to numerical magnitudes, indicates suggestively the present scope of sonics.
TTS Produced by Low-Level Tones and the Effects of Testing on Recovery
Authors: Bell Donald W. , Fairbanks Grant
Published: September 2005

To evaluate TTS from exposure frequencies presented at low level and the effects of threshold testing on recovery, sensation levels of 10, 20, 40, and 60 dB and frequencies of 1, 2, and 4 kc/sec were presented for 60 sec, followed by 0, 15, 30, or 60 sec of silence before testing. Twenty audiometrically normal subjects were used. At all frequencies, TTS was found to be a monotonic function of level if measured within 5 sec after exposure. Recovery from TTS induced at 60 dB SL appeared faster than at 40 dB SL. Early recovery rate increased directly with level of exposure when recovery was measured by continuous tracing, and, with a few exceptions, the same relation was found when recovery was measured by testing after intervals of silence. At 40 and 60 dB SL, TTS varied directly with frequency when measured immediately after exposure. Continuous postexposure threshold testing significantly retarded recovery produced by all frequency-by-level combinations. Thirty seconds after exposure, this retardation averaged about 3.5 dB. Recovery after 15 sec of silence was approximately equivalent to recovery after 60 sec of continuous testing.
Bone-Conduction Thresholds for Sonic and Ultrasonic Frequencies
Authors: Corso John F.
Published: September 2005

Several investigators have reported that high-intensity, bone-conducted sounds in the ultrasonic region above 20 kc/sec can produce auditory sensations in individuals with normal hearing. The present study was performed to establish the curve of audibility for bone conduction from approximately 5 to 100 kc/sec in a group of subjects with no audiometric or otological abnormalities. Fifty-three male and 50 female subjects, ranging in age from 17 to 24 years, were tested on the left or right ear only by a modified method of limits, with all tests being conducted in an anechoic chamber. A crystal transducer, calibrated in a water medium, was used to transmit the acoustic energy to the mastoid portion of the temporal bone. For 38 male and 37 female subjects screened from the larger sample by means of an otological examination and an air-conduction audiometric test from 250 cps to 8 kc/sec, the curve for the mean threshold of hearing showed a very sharp rise between 10 and 20 kc/sec with a slope of approximately 50 dB/octave, and a gradual rise from 20 to 100 kc/sec with a slope of approximately 15 dB/octave. The maximal discrepancy between men and women was approximately 5.5 dB (at 14 kc/sec). The standard deviations ranged from approximately 2 to 15 dB, with the maximal value for each group occurring at 16 kc/sec. In general, the results of the present study are in agreement with earlier fragmentary reports.
Absorption of Sound in Humid Air at Low Frequencies
Authors: Horiuchi I.
Published: September 2005

This paper represents a continuation of the work in absorption of sound in humid air initially reported on at the Fifty-First Meeting. Results have been obtained at temperatures of 0°C and 55°C for the range of pressures from 20 cm Hg to atmospheric and water vapor concentrations from 2% relative humidity to 80% relative humidity, in the audible range 300 cps to 1100 cps. It is found that the absorption coefficients in general closely conform to the Knudsen-Kneser curves but exhibit large departures at extreme relative humidity values. Secondary maxima were not found. (This work was supported by subcontract with the University of Michigan under Signal Corps Contract DA-36-039-sc-52654.)
Some Experimental Results Concerning the Propagation of Sound over Ground
Authors: Keast David N. , Wiener Francis M.
Published: September 2005

Under contract with the U. S. Army Signal Corps (contract No. DA-36-039-sc-64503), field studies have been undertaken to investigate the physics of outdoor sound. The propagation of sound over ground in the speech frequency range was studied as a function of distance, terrain, ground cover, wind speed and direction, temperature, and humidity, etc. Propagation over open, level ground, through dense evergreen forests, and between mountain tops was studied in the frequency range between 300 cps and 5000 cps. Extensive micrometeorological instrumentation was utilized. Results were generally expressed as attenuation in excess of inverse square law as a function of distance and frequency for a wide range of meteorological and terrain conditions. Over level ground, the excess attenuation was found to be greater for upwind than for downwind propagation by as much as 30 db. This is due to the presence of vertical temperature and wind gradients, and is in general agreement with Ingard's findings. In hilltop-to-hilltop propagation, large, long-period fluctuations in the received sound pressure level were observed; wind direction appears to be of secondary importance. In dense forests, sound absorption and scattering control. Attenuation coefficients measured in evergreen forests are comparable to those obtained by Eyring in Panamanian jungles.
Propagation of Acoustic-Gravity Waves from a Small Source above the Ground in an Isothermal Atmosphere
Authors: Pierce Allan D.
Published: September 2005

A theoretical discussion is presented of the influence of gravity on sound propagation from a small source in an isothermal atmosphere where ambient pressure and density decrease exponentially with height. A solution for the free-space case is derived that indicates that waves with angular frequency ω between (γ − 1)12g/c and (γ/2)g/c will not be propagated, while those with ω between 0 and (γ − 1)12(g/c) cosθ will not be propagated in a direction making an angle of θ with the vertical axis. A formal solution incorporating appropriate boundary conditions at the ground is derived and discussed. The field along the vertical line passing through the source is found explicitly. A consideration of the energy intensity shows that no energy is propagated within a cone above and below the source if ω < (γ − 1)12g/c, A calculation of the intensity for the case when (γ − 1)12g/c < ω < (γ/2)g/c indicates that the energy flowing from the source tends to concentrate in the lowest layers of the atmosphere. The field for large horizontal distances appears as a sum of a direct wave, a reflected wave, and a surface wave. Reflection coefficients are derived, and the criteria for the surface wave to be dominant are discussed.
Propagation at Short Ranges of Elastic Waves from an Impulsive Source near a Fluid-Two-Layer-Solid Interface
Authors: Spitznogle F. R. , McLeroy E. G.
Published: September 2005

A recent theory by Strick concerning the prediction of the pressure field produced by an impulsive sound source near a fluid-homogeneous-solid interface is extended so that it is applicable to a system consisting of a fluid half-space overlying an elastic solid layer that rests on a solid half-space. Experimental-model data are presented to substantiate the theoretical results. It is concluded that in the real environment interface waves could be of importance in problems of sound propagation near the ocean floor. This would imply that it is often not sufficient to think of the ocean bottom as a fluid in solving such problems. It is felt that this study might help to explain certain previously noted discrepancies between full-scale experiment and prior layered-liquid formulations of this propagation problem.
Some Intense, Low-Frequency, Underwater Sounds of Wide Geographic Distribution, Apparently of Biological Origin
Authors: Walker R. A.
Published: September 2005

A certain intense, underwater, transient sound has been observed over extended areas of the Atlantic and Pacific Oceans. The power spectrum for a single pulse of this sound is strongly peaked, energy being confined to a narrow band centered in the vicinity of 20 cps; the sounds, accordingly, have been named twenty-cycle pulses. A single pulse typically lasts about one second; the pulses normally occur in trains, or groups, characterized by remarkably regular repetition rates. A common rate is one pulse approximately every 10 sec, although others are observed. A typical pulse train is of several minutes' duration; separated by silent periods two to three minutes in length, pulse trains often repeat for many hours. On the continental shelf south of New England, the positions of scores of sources of this sound have been determined by remote acoustic ranging; the sources are found to move. Speeds are typically a few knots. Radiated sound levels are so high that the sources are detectable tens of miles away. Source densities of only one in several hundred square miles are most common. Movements appear random, suggesting that the source is biological. The low areal density, the high source level, and speeds of a few knots that are sustained for hours suggest a large animal. Characteristics possibly correlated with the sounding cycles of whales are apparent. The hypothesis that the sounds originate from the heartbeats of whales appears credible on several counts.
Relationship between the Transmission Loss and the Impact-Noise Isolation of Floor Structures
Authors: Heckl M. , Rathe E. J.
Published: September 2005

Transmission loss and impact noise are two important aspects of the properties of floors. With the application of the principle of reciprocity, a relation is derived for floors with hard surfaces that makes it possible to estimate the impact noise from transmission loss or vice versa. If both are known, some insight can be gained on the existence of leakage paths and flanking by side walls, or the efficiency of floor-surfacing materials.
New Interpretation of the Stereophonic Effect in Lauridsen's and Similar Binaural Experiments
Authors: Schroeder M. R.
Published: September 2005

In 1954, H. Lauridsen reported an experiment which gave a remarkable stereophonic effect using a single input signal. The signal was fed to both ears once directly in phase and a second time (delayed by 50–150 milli-seconds) in antiphase. In a recent paper [Akust. Beib. 6, 482–488 (1956)], G. R. Schodder gave an explanation of the resulting stereophonic effect which is based on the analogy between Lauridsen's (and similar) experiments and hearing conditions in rooms. In this paper a different interpretation will be offered. These experiments are recognized as resulting in two different intensity-versus-frequency responses in the paths to the two earn (two interlaced comb-filters in Lauridsen's case). The presence of such different (but indiscriminable by the ear) intensity-versus-frequency responses is postulated as the essential prerequisite that stereophonic effects be obtained from a single input signal. This theory accounts for most of the observed phenomena which could not or not easily be explained by Schodder's interpretation such as his own observation of a strong effect at very high frequencies. To further support this view a number of differential filtering experiments have been conducted. A magnetic tape recording demonstrating some of the results will be played. An earlier view held by this author, namely, that all that is needed to produce a stereophonic effect are two physically different wave forms which would sound alike individually, could not be sustained. Several experiments with pairs of all-pass filters having different phase-versus-frequency characteristics did not give the strong stereophonic illusion observed with differential intensity filtering.
Fundamental Operation of Quartz Transducers in the VHF Range, Using Silicate Bonds
Authors: Eggers F. G.
Published: September 2005

A firm silicate bond between a quartz transducer and the substrate allows bonded transducers to be ground down to a thickness of 10 to 20 μ, achieving fundamental operation up to 300 Mcps. The acoustic bandwidth becomes better than 75% and the insertion loss is less than 30 dB for a one-port delay line model with 190-Mcps center frequency.
Role of Intensity and Time Differences in Localizing Low-Frequency Tones
Authors: Moushegian George , Jeffress Lloyd A.
Published: September 2005

Subjects matched the position of a 500-cps tone by adjusting the interaural delay for a wide-band noise. The stimuli were presented alternately by means of earphones, using a gate having a rise and decay time of 10 msec. The tonal signal was adjusted by the experimenter to have a certain combination of interaural time difference (phase) and intensity difference. In some cases these were in accord and in some, in opposition. The subject attempted to match the localization of the tone by adjusting the interaural time difference for the noise stimulus by means of a variable lag-line. Under some of the extreme conditions these matches were hard to make, but for most combinations the subjects experienced no great difficulty. Data will be presented for four subjects. They show the combinations of time and intensity differences which yield equivalent localizations. The responses of all of the subjects can be fitted reasonably well by a single equation, but the constants of the equation differ markedly among the subjects. The data show further that the localizational effects of time and intensity are not simply additive. (This work was performed under Bureau of Ships Contracts NObsr-52267 and NObsr-72627.)
In Defense of Rayleigh's Scattering from Corrugated Surfaces
Authors: Marsh H. W.
Published: September 2005

Arguments are presented justifying the Rayleigh solution, despite criticisms based on the use of outgoing waves only.
Significance of Complex Wave and Random Excitations
Authors: Morrow Charles T.
Published: September 2005

Until recently, vibration testing to verify performance and reliability under vibration has been done almost exclusively in terms of fixed frequencies applied one at a time, or a “single frequency” that is swept slowly back and forth over a specified frequency range. People responsible for reduction of vibration data have been under pressure to present the data in such a way that it leads directly, with no apparent ambiguity, to specification of acceleration levels for use in such tests. In this paper, an attempt is made to distinguish clearly between data reduction and the process of writing specifications. A preliminary treatment of the interaction of simultaneous excitations in separate bands is given, together with a discussion of the relation of this to data reduction and specification writing. A brief discussion of the philosophy of specifications is also presented along with its application to the testing of parts and sub-assemblies as well as the testing of completely assembled units or components. A basis is given for distinguishing between periodic or quasi-periodic and random vibration for purposes of data reduction.
Application of Nonlinear Vibration Isolators
Authors: Becker Carl
Published: September 2005

Suitable combinations of nonlinear coil springs are developed in the form of vibration isolators to provide relatively high isolation values for small static deflections. Isolator properties, determined by spring parameters are; static deflection, dynamic spring rate, linear range, and snubbing effect. Inherent features of these isolators are lateral as well as axial stability, which, together with comparatively small over-all dimensions are found to be of advantage in practical application.
Effects of Waveform Correlation and Signal Duration on Detection of Noise Bursts in Continuous Noise
Authors: Raab David H. , Osman Eli , Rich Edward
Published: September 2005

Studies of the masking of noise bursts by continuous noise revealed the pedestal effect previously reported by others for 100-cps tones. The correlation ρ between mask and probe waveforms was found to affect detection: the pedestal effect—evidenced with ρ = 1 or with ρ = −1—was absent with ρ = 0. In a second experiment, the pedestal effect was found to diminish as probe bursts were shortened in duration from 100 to 5 msec. The results of these and related experiments provide support for the energy-detection model of Pfafflin and Mathews. Tone and noise probes are considered to be detected by virtue of the energy changes they produce. Some features of the energy-detection model are discussed.
Normalization of the Voice Spectrum
Authors: Smith Caldwell P.
Published: September 2005

Measurement of the spectrum pattern of voice signals by a method that normalizes (i.e., makes the measurement unresponsive) with respect to amplitude fluctuations offers some powerful advantages. The relative amplitude at all frequency positions in the voice spectrum pattern is significantly correlated with the particular speech event; therefore a measurement of the total spectrum pattern offers a means of maximum utilization of the speech signal information. Normalization has the effect of slowing down the rate of change of the signal parameters that specify the voice spectrum, abstracting the common-mode fluctuation due to voice amplitude and specifying it as a separate parameter. Further, a specification of the normalized spectrum patterns of speech offers in principle a more economical specification than one in which formant frequencies are specified as independent parameters. The normalizing method has been reported previously [C. P. Smith, J. Acoust. Soc. Am. 28, 159 (1956)]; some speech data taken with normalization are presented.
Effect of Third-Formant Transitions on the Perception of the Voiced Stop Consonants
Authors: Harris K. S. , Hoffman H. S. , Delattre P. C. , Liberman A. M.
Published: September 2005

The pattern playback was used to generate synthetic syllables consisting of a wide range of second- and third-formant transitions in initial position with the vowels i and ae. It was found that third-formant transitions affected the perception of the stop consonants. (The effects of the second-formant transitions were as previously reported.) When the third formants and their associated transitions were added at the frequency levels appropriate to each of the two vowels, positive transitions strengthened the perception of d at the expense of b or g, while negative transitions had the opposite effect. There was some evidence that variations of the steady-state level of the third formant changed the effect of a given third-formant transition. The results suggest that the effect of third-formant transitions is largely independent of the second-formant transitions with which they are combined. (This work was supported in part by the Carnegie Corporation of New York, and in part by the Department of Defense in connection with Contract DA49-170-sc-1642.)
Some Cues to the Voiced-Voiceless Distinction among the Intervocalic Stops in English
Authors: Lisker Leigh
Published: September 2005

Phonetic description and evidence from spectrograms suggest that (1) perception of the voicing distinction among stops involves several acoustic features; and (2) these features are likely to be of unequal importance in different contexts. The contrast between p and b, for example, comprises aspirate vs nonaspirate articulation, presence vs absence of glottal tone, strong vs weak force of articulation, longer vs shorter duration of preceding vowel. The intervocalic post-stressed position was chosen for study because the voiced-voiceless distinction is here phonetically minimal and because spectrograms showed consistent differences in closure duration. Experiments with synthetic speech and tape recordings of real speech permitted measurement of the cue value of closure duration in relation to duration of preceding vowel, presence or absence of glottal tone, and formant transitions preceding and following closure. For certain conditions, closure duration suffices to distinguish between p and b in post-stressed intervocalic position. (This work was supported in part by the Carnegie Corporation of New York, and in part by the Department of Defense in connection with Contract DA49-170-sc-1642.)
Initial and Intervocalic Cues for the Perception of Liquids and Semivowels
Authors: Gerstman L. J. , Lisker L. , O'Connor J. D. , Liberman A. M. , Delattre P. C. , Cooper F. S.
Published: September 2005

Experiments with CV syllables synthesized on the pattern playback have demonstrated that the liquids r, l, and semivowels w, j, are distinguished from one another by variations in the direction and extent of the second- and third-formant transitions. For each phone, the onsets of the transitions are marked by brief steady states whose frequencies remain fairly constant from vowel to vowel: the second-formant onset is low for w (ca 600 cps), high for j (ca 2400 cps), and intermediate for r or l (900–1800 cps); the third formant for l is practically straight, but for r its onset lies just above the second-formant onset. In VCV combinations, the steady states connect the transitions from the preceding and following vowels. As in initial position, the second-formant termination distinguishes w from r-l from j and the third formant separates r from l. When the preceding and following vowels are identical, the two sets of transitions are mirror images of each other, but when the two vowels (and thus the transitions) are different, identifications are governed by the transitions to the following vowel. Despite the doubling of the transition cues, w, r, l, and j are little more intelligible intervocalically than they are initially. (This work was supported in part by the Carnegie Corporation of New York, and in part by the Department of Defense in connection with Contract DA49-170-sc-1642.)
Effect of Jet Structure on Noise Generation by Supersonic Nozzles
Authors: Mull Harold R.
Published: September 2005

In this study, the noise field surrounding the jets from two supersonic convergent-divergent nozzles were measured. The jet pressure ratio was 30:1, resulting in an exit March number of about 2.9. The results will be presented in a series of contour maps and the noise sources will be located along the jet boundary. The effect of supersonic and subsonic regimes on noise sources and intensity will be shown.
Changes of Jet Noise by Mixing and an Upper Limit on Jet Noise Production
Authors: Westervelt Peter J. , Dyer Ira , Franken Peter A.
Published: September 2005

A simple analysis is given of the effect on jet noise by mixing with an induced secondary air flow. The combination of the secondary air with the primary air of the jet creates a new jet stream of larger area and lower velocity. Power level, spectrum, and directivity changes are presented. The mixing mechanism provides a possible explanation of the noise reduction of such devices as ejectors, corrugated nozzles, and vaned nozzles. The noise reduction is given as a function of several ratios involving the mixing area, the jet temperature, and the forward speed. Also, jet noise is examined as a function of efficiency of conversion of jet stream power to acoustic power. An upper limit appears to exist on the efficiency, and this upper limit is estimated by a simple argument. The resulting limit is compared with experimental values.
Backscatter of Sound from a Rough Boundary
Authors: Patterson Robert B.
Published: September 2005

The paper demonstrates some similarities between the backscatter, as a function of grazing angle, of sound from the deep ocean bottom and that of a variety of other types of wave radiation from a variety of rough boundaries. A mathematical model of a rough boundary as a backscatterer of wave radiation is proposed and compared with measurements of several types of backscatter. This model has the form Sθ = 10  log[A (B+C)], where Sθ is the scattering strength of the boundary as a function of grazing angle, A is the Rayleigh reflection coefficient, B is a weighting constant times some type of a random distribution density function, and C is a constant times the sine of the grazing angle raised to a constant power.
Jet Exhaust Muffling with Screens
Authors: Kirchman E. J. , Miller E. H. , Owen A. L.
Published: September 2005

Tests of screens as noise suppressors have been conducted by the Martin Company. Configurations of approximately ten (10) types which led to the development of a lightweight, noncoupled system, with desirable performance characteristics, will be discussed.
Observations on Inharmonic Signals
Authors: de Boer Egbert
Published: September 2005

Schouten's “residue” can be readily observed when a group of closely spaced Fourier components is presented. Such a sound often exhibits a basic pitch, especially when the complex stimulus is harmonic. The pitch level is then judged to be the fundamental frequency (which in this case equals the difference frequency). In the present study signals consisting of a restricted number of equally spaced components were investigated. The sound observed is steady in both pitch and timbre even when the stimulus is inharmonic. The pitch level however corresponds not necessarily to the difference frequency as can be demonstrated when all components are displaced by the same amount in frequency. For small departures from harmonicity, the pitch appears to follow the direction of this frequency shift of the complex. More specifically, the relative pitch change is approximately equal to the relative frequency change of the central component, the timbre not being affected much. The timbre depends strongly upon the relative phases of the components, so that it seems closely tied to the shape of the envelope of the signal's wave form. [This work was supported in part by the U. S. Army (Signal Corps), U. S. Air Force (Office of Scientific Research, Air Research, and Development Command), and the U. S. Navy (Office of Naval Research).]
Pitch of a Train of Pulses of Random Polarity
Authors: Cramer Elliot M. , Licklider J. C. R.
Published: September 2005

There has recently been considerable discussion of periodicity pitch as opposed to pitch due to spectral energy concentrations. The present investigation deals with a stimulus which appears to display both characteristics in clearly separable form. A train of short evenly spaced pulses was modulated by a noise generator so that the polarity of a given pulse was chosen in a random manner. Since the average power spectrum is approximately flat, it might be expected that the stimulus would have the character of random noise. It is found, however, that the stimulus has a steady pitch-like quality upon which is superimposed an intermittent “chirpiness“ which is definitely tonal. The latter effect is explained in terms of the statistical properties of the short-term power spectrum, but the former seems to be due to the periodicity of the stimulus.
Statistical Derivation of an Importance Function for Speech at Threshold
Authors: Bilger Robert C.
Published: September 2005

Fletcher has based his prediction of hearing loss for speech from an audiogram upon weights derived from the function ∫0fG1df. His equation for predicting hearing loss is considered analogous to a linear, multiple-regression equation. If the analogy is appropriate then it should be possible to reconstruct the ∫0f G1df function from a set of multiple-regression weights computed by least squares technique from a set of data giving hearing loss for speech and for 250, 500, 1000, 2000, and 4000 cps. Multiple-regression computations were carried out on the set of data given by Fletcher and on a set of data assembled by the writer. There is a discrepancy between the function as derived from data on filtered speech and as derived from the multiple-regression technique applied to data collected from hard-of-hearing subjects. It is argued that this discrepancy is due to the difference between the speech materials used in the original determination (monosyllables) and that conventionally used to measure hearing loss for speech clinically (spondees). [This research was supported by a grant (B-243) from the National Institutes of Health.]
Narrow-Band Investigations of the Longitudinal Space-Time Correlation Function in Turbulent Airflow
Authors: Bakewell Henry P.
Published: September 2005

The longitudinal space-time correlation function of the fluctuating pressures at the wall in turbulent airflow has been investigated, using the U.S. Navy Underwater Sound Laboratory's 3.5-in. turbulent-pipe-flow facility. Data were obtained for various Reynolds numbers and transducer separations, and were analyzed by using filters of constant 30-cps bandwidth. These measurements of the longitudinal space-time correlation function are compared with a mathematical model that takes into account the effect of finite filter bandwidths.
Reverberation from a Deep Scattering Layer Measured with Explosive Sound Sources
Authors: Marshall J. R. , Chapman R. P.
Published: September 2005

The acoustic properties of a deep scattering layer located north of Bermuda were examined over the frequency range from 0.4 to 6.4 kc/sec. Octave-band scattering strengths were measured in the two octaves from 1.6 to 6.4 kc/sec. A broad peak in scattering strength was observed whose center frequency decreased over the sunset period from an average daytime value of 5.4 kc/sec to an average nighttime value of 4.8 kc/sec. The variations in measured scattering strengths, resonant frequencies of scattering-strength peaks, and layer depths were consistent with those expected from a migrating layer of scatterers possessing swim bladders of constant volume.
Calibration of Piston Transducers at Marginal Test Distances
Authors: Sabin Gerald A.
Published: September 2005

Guidelines for selecting adequate test distances for sensitivity measurements involving two piston transducers are derived and discussed in terms of the transducer dimensions and the wavelength. Applicable correction factors are computed for use in either a reciprocity or a comparison calibration when short distances are necessary. Experimental data obtained at frequencies in the megacycle-per-second range are shown to support the validity of the analysis and the computations.
Medial Superior-Olivary-Unit Response Patterns to Monaural and Binaural Clicks
Authors: Moushegian George , Rupert Allen , Whitcomb Milton A.
Published: September 2005

Single units in the accessory nucleus of anesthetized cats, isolated with tungsten microelectrodes, show a delicate sensitivity to interaural time and intensity differences. A click delivered to one ear produces a response that may be inhibited by a click presented with some time difference to the opposite ear. When a response occasionally does occur during such inhibition, its latency is increased significantly. Both the amount of this shift and the occurrence of inhibition are dependent upon the interaural time difference. In one well-studied instance, when the interaural time difference was too large to produce inhibition, an increase in the intensity of the driving click produced effective inhibitory interaction. Monaural unit responses show such variations in latency to a click stimulus that, whenever the effects of time and intensity disparities are under investigation, time measurements should be made from N1 of each cochlea.
On Plane, Spherical, and Cylindrical Sound Waves of Finite Amplitude in Lossless Fluids
Authors: Blackstock David T.
Published: September 2005

An approximate wave equation ux+(a/x) u − (β/c02)uut′ = 0, where t′ =t − x/c0, is derived for progressive plane (a = 0), spherical (a = 1), and cylindrical (a = 12) waves of finite amplitude in a lossless fluid. In the case of spherical and cylindrical waves, it is required that the spatial coordinate x be large. Solutions of the equation satisfying an arbitrary but given boundary condition are obtained. When the source excitation is sinusoidal, generalized Bessel-Fubini solutions may be found. Another set of exact solutions is found that corresponds to a sawtooth wave. From these solutions, amplitude-decay formulas are derived that agree with results obtained previously by Mendousse, Rudnick, Westervelt, and Naugol'nykli.
Systematic Shifts in the Judgment of Octaves of High Frequencies
Authors: Elfner Lloyd
Published: September 2005

Experiments are reported on the effect of d-amphetamine, sleep loss, and continuous intense crossear stimulation on the subjective judgment of octaves of high frequencies. Crossear stimulation produced significant decrements in the subjective octaves of 2000-, 4000-, and 8000-cps tones. The administration of d-amphetamine previous to crossear stimulation prevented decrements in the subjective octaves of 2000- and 4000-cps tones. A significant depression of the decrement for the octave of an 8000-cps tone was noted. Sleep deprivation also produced significant decrements in the pitch of the high frequencies studied. d-amphetamine produced almost complete recovery of the decrement produced by sleep loss within one-half hour of administration. Continued crossear stimulation, d-amphetamine, and the combination of the two, failed to produce significant changes in loudness of the high-frequency tones used. It can be assumed that all octave determinations were made at equal-loudness levels, and that the shifts in octave judgments cannot be explained by pitch change with loudness. A theoretical model for pitch discrimination, located in the central nervous system, is discussed.
Resonant Vibration of a Cone
Authors: Eisner E.
Published: September 2005

The algebraic expressions given by earlier workers are used to compute the properties of longitudinally resonant cones. From the results, it is suggested that conical vibrators, driven by “stepped” amplitude transformers, would make useful resonators for fairly large amplitude. The ease, compared with vibrators having curved tapers, with which such a combination can be made outweighs its disadvantages when a fairly small number (greater than 1) of identical amplitude transformers is required.
Numerical Evaluation of the Ultrasonic Attenuation in Metals as a Function of the Magnetic Field
Authors: Shah B. P. , Meijer Paul H. E.
Published: September 2005

The expression for S11 for the ultrasonic attenuation in metals as a function of the magnetic field, as given by Cohen, Harrison, and Harrison, has been calculated numerically on the IBM-1620 digital computer for an interval of magnetic-field values corresponding to those obtainable in the laboratory. The results are compared with those given by Cohen et al., which corresponds to retaining only the n = 0 term in a certain series. The actual values of S11 obtained with n>0 are quite high as compared to those obtained by using the approximation.
Modification of Noy Tables
Authors: Kryter K. D. , Pearsons K. S.
Published: September 2005

A set of somewhat modified tables relating noy values to band sound-pressure levels is presented.
Background-Noise Levels in Suburban Communities
Authors: Ostergaard Paul B. , Donley Ray
Published: September 2005

Noise surveys have been made in a number of recently developed suburban communities, as well as in well-established communities that are not penetrated by major expressways or railroads. Measurements of background-noise levels are presented and compared with earlier published data. The findings indicate a change in midfrequency-band levels that should be considered in developing zoning and nuisance-control statutes.
Dilatation Constants and Complex Ratio from Forced Vibration of a Free Viscoelastic Sphere
Authors: Lee T. M.
Published: September 2005

The technique of forced vibration has been applied to the study of the properties of viscoelastic materials. It is found, through the analysis of a free sphere with a harmonic oscillating internal source, that the vibration-amplitude ratio of two measuring points is associated with the complex dilational constants and a complex ratio directly related to the complex Poisson's ratio of the material. From the criterion of maximum amplitude ratio (i.e., by adjustment of the frequency of the source for the amplitude ratio to reach a maximum), these properties can be expressed in terms of the amplitude ratios and their frequencies. For the convenience of laboratory testing, two particular amplitude ratios, in conjunction with their frequencies, have been considered for this purpose. Simple expressions are given, relating the properties of the test material to quantities measurable in the laboratory: namely, the maximum amplitude ratios and their corresponding frequencies.
Initial Response of a Fluid-Filled, Elastic, Circular, Cylindrical Shell to a Shock Wave in Acoustic Medium
Authors: Peralta L. A. , Raynor S.
Published: September 2005

The initial response of a fluid-filled cylindrical shell immersed in an acoustic medium when struck by an acoustic shock moving in the external fluid is solved by means of integral transformations. Both the fluid contained in the shell and the exterior fluid are assumed to obey linear wave equations; the two fluids are assumed to possess dissimilar properties. The effects of transverse shear and rotatory inertia are included in the equations governing the shell motion. The solution is limited to the “front” region of the shell.
Response of a Simply Clamped Beam to Vibratory Forces and Moments
Authors: Snowdon J. C.
Published: September 2005

The driving-point impedance and the force and moment transmission to the terminations of a simply clamped beam have been determined when the beam is excited at its midpoint by an alternating force, by a moment, and by a force and moment of like phase. The influence of rotary inertia, shear displacement, and internal damping upon the response of the beam has been considered in detail. When the beam is excited by an applied moment, the mean level of the force exerted upon the beam terminations is found to increase essentially in proportion to the square root of frequency—at frequencies above the first resonant frequency of the beam. In consequence, the transmitted force attains values at high frequencies that are significantly greater than the constant value observed at low frequencies. When the beam is excited simultaneously by an in-phase force and moment, the force exerted upon the beam terminations can likewise take much larger values at high frequencies than at low; moreover, this transmitted force can greatly exceed in magnitude the force that is exerted in the absence of the applied moment.
Variation of Electroelastic Constants of Polycrystalline Lead Titanate Zirconate with Thoroughness of Poling
Authors: Berlincourt D.
Published: September 2005

The complete set of electroelastic constants of a tetragonal lead titanate zirconate ceramic (PZT-5A) is shown as function of the invariant coupling factor ki3 (and, thus, as function of the thoroughness of poling). Interrelations among the important piezoelectric-coupling factors (k33, k31, kp, kt, ki1 = k15, and ki3) are also shown. Most measurements were repeated on a rhombohedral lead titanate zirconate ceramic {Pb0.9875Nb0.025(Zr0.65Ti0.35)0.975O3}. With the rhombohedral material, anisotropies increase throughout the entire range of ki3; but, with PZT-5A, anisotropies increase sharply only at the highest values of ki3 (range ∼0.6 to 0.75). Anisotropies of the elastic constants are much greater at constant D than at constant E. It is demonstrated that changes inelastic and dielectric constants near saturation are relatively severe, even with small changes in the coupling factors.
Displacement Measurement by Electronic Counting Seymour Edelman
Authors: Smith Ernest R. , Jones Earle
Published: September 2005

This paper reports further progress in our development of methods for calibrating vibration pickups using the wavelength of light as the standard length. Methods described previously [J. Acoust. Soc. Am. 27, 728 (1955); 28, 780 (1956) and to be published] are fatiguing, time consuming, and require trained personnel. Use of a photomultiplier and electronic counter to count interference fringes passing a slit makes it possible to measure fairly large as well as small amplitudes over a wide frequency range while the use of an averaging technique improves the sensitivity of the counting method to a small fraction of a wavelength of light. Measurement by counting is rapid and easy and can be performed by untrained personnel after the equipment is set up working.
Measurement of Mechanical Impedance and Its Applications
Authors: Hixson E. L. , Wittenborn A. F.
Published: September 2005

The impedance concept for mechanical elements is briefly developed through the analogy to electric circuits. This concept then makes the whole field of circuit analysis with its highly developed set of rules, theorems, and mathematics available for the solution of mechanical problems. Many devices are available for the application of forces and the measurement of motion and force. Some of these are combined in several devices designed specifically to measure the driving-point impedance of soils. An analog computer is presented that takes force and velocity information from the impedance devices, computes their complex ratio and plots impedance as the measurement is being made. Examples of the impedance of soils, sponge rubber, and a simple beam are presented. Impedance information is used to predict the motion of the bar to a sinusoidal driving force and Norton's equivalent circuit is used to predict the motion of a mass attached to the bar. Finally, the transient response of a mass dropped on sponge rubber is predicted from the equivalent circuit as determined from impedance measurements. Each of these cases is verified experimentally.
Remarks on the Mean Free Path Problem
Authors: Hunt F. V.
Published: September 2005

The Jaeger-Sabine-Kosten mean free path lc is not the same as the mean free paths ls and lAN found by Knudsen and by Allred and Newhouse. All have in common the same mean free directed path length ld given by the ratio of the room volume to the apparent area presented in the specified direction, but they differ in the method used to compute the average of ld over all directions: lc is an apparent-area weighted average, which has the value 4V/S for rooms of any shape; ls and lAN are unweighted solid-angle and direction-cosine averages whose values differ slightly but systematically from 4V/S. The mean directed collision frequency vd is the inverse with respect to sound speed of the mean free directed path length (vdld=c). The unweighted solid-angle average of vd is cS/4V for rooms of any shape, but the apparent-area weighted average of vd differs systematically from cS/4V in about the same way that ls differs from 4V/S. Since the rate of sound decay in rooms is directly proportional to the frequency of wall reflections, the “collision frequency” concept is nominated to succeed the “free path” concept. However, the analysis of these averaging processes indicates that significant errors in the assessment of sound decay can be introduced by using either preaveraged mean free paths or preaveraged mean collision frequencies. These particular errors can be avoided by first computing the residual sound as a function of time for each representative direction of propagation before summing up these directional contributions at the receiving point.
Masker Level and Noise-Signal Detection
Authors: Campbell Richard A.
Published: September 2005

Threshold signal-to-noise ratios for a filtered thermal-noise signal presented in an independent thermal-noise masker are reported. The parameters of primary interest were the sensation level of the masking noise and the center frequency and bandwidth of the signal noise. It was found that the threshold-signal/noise ratios were not constant once the masker was well above threshold. Rather, the obtained masked thresholds revealed an interaction between signal frequency and masker level. This interaction would appear to be related to the numbers of eighth-nerve fibers with thresholds at different stimulus levels. This relationship is interpreted as indicating that, below about 60 dB sensation level, differential-intensity information may be conveyed primarily by changes in the number of eighth-nerve units activated. At higher stimulus levels, differential-intensity information would seem to be conveyed by a different group of neurons primarily by changes in the rate of their firing.
Methods of Generating High-Intensity Sound with Loudspeakers for Environmental Testing of Electronic Components Subjected to Jet and Missile Engine Noise.
Authors: Hilliard John K. , Fiala Walter T.
Published: September 2005

Unsymmetrical reverberant sound chambers having cubical contents ranging from 30 cubic inches to 20 cubic feet and plane wave tubes two to four inches in diameter will be described. These chambers and tubes are energized by various types of loudspeakers to produce the frequency range required for the environmental testing of electronic components which may be subjected to high sound fields in airframe and missile application.