bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conductivity and Viscosity Effects on Wave Propagation in Piezoelectric Crystals
Authors: Kyame Joseph John 
Published: September 2005

The effect of electrical conductivity and viscosity of the piezoelectric medium propagating plane waves has been studied. The solution of Maxwell's field equations and Newton's law of force in the general medium gives the modified elastic, piezoelectric, etc., constants necessary for determining the phase velocities of the plane waves. These modified constants are found to be complex and frequency dependent. Thus the propagation constants for the waves are complex and frequency dependent.
A particular example, propagation in the 1-direction of ammonium dihydrogen phosphate, is considered.
Perstimulatory Auditory Fatigue for Continuous and Interrupted Noise
Authors: Carterette Edward C. 
Published: September 2005

Perstimulatory fatigue, or adaptation, is measured by a simultaneous loudness balance or median plane localization of a dichotically presented acoustic stimulus. After one ear has been stimulated for a period of time, it is usually found that the variable or comparison stimulus must be reduced below the prefatiguing intensity in order to maintain the loudness match or localization balance.
Five observers made median plane localizations of a continuous 100–5000 cps band-pass noise before, during and after a seven-minute fatiguing period. The fatiguing stimuli were continuous noises at 30, 60, 87, and 100 db SPL, and noises interrupted at 1, 2, 5, 9, and 12.5 ips with both burst level and noise-time fractions held constant at 90 db SPL and 0.5, respectively.
It was found that (a) the time required for fatigue to reach an apparent asymptote is at least seven minutes, about twice that required for pure tones; (b) the maximum fatigue increases with the intensity of the fatiguing stimulus and the function is positively accelerated; (c) for a fixed intensity of fatiguing noise, the maximum fatigue for the highest rate of interruption used (12.5 ips) is less than that obtained with a continuous noise having the same over-all level (87 db).
During the course of fatigue, the between-observer variations (standard deviations) of the balances tend to be greater than the within-observer variations; the reverse is true for the post-fatigue period.
On the Contribution of a Contained Viscous Liquid to the Acoustic Impedance of a Radially Vibrating Tube
Authors: Robey Donald H. 
Published: September 2005

The impedance presented to the inside surface of a hollow, liquid filled, radial cylinder of finite length has been determined theoretically. It was assumed that the liquid was retained by pressure-release caps or one pressure-release cap and one rigid cap at each end. For a loss-free liquid it is shown that the reactance presented to the cylinder wall becomes infinite whenever the liquid has a longitudinal or coupled radial resonance.
A sizeable resistance may appear when a viscous liquid is used. This is because the geometry of the arrangement is ideal for creating large shear losses. Exceptions to this occur for high frequencies where the wavelength is small in comparison to the cylinder length.
Elastic Constants of Aluminum from 20°C to 400°C
Authors: Zucker Charles 
Published: September 2005

The use of the ultrasonic pulse technique as a means of determining the elastic constants of polycrystalline aluminum at high temperatures has been considered in some detail.
The C11 and C44 elastic constants, Debye temperature, and Young's modulus were computed from the longitudinal and transverse velocity measurements. The variations of these constants with temperature showed the predicted linear decrease expected from solid state theory.
Scattering of High-Frequency Sound Waves in Polycrystalline Materials
Authors: Bhatia A. B. 
Published: September 2005

The scattering, and hence attenuation, of plane dilatational and shear waves due to random orientation of the grains is calculated on the assumptions that (1) the wavelength is large compared to the grain size and (2) the variations in elastic moduli from grain to grain are small compared to the average values of these moduli for the bulk material. Previous treatments of this problem are incomplete; for incident dilatational waves they are valid for a fluid (rigidity modulus=0), and for incident shear waves they describe inadequately the angular dependence of the intensity of the scattered shear waves. It is shown in this paper that for both of these types of incident waves both the scattered dilatational and shear waves are produced; the energy carried away from the incident beam by the latter is 32(Vl/Vs)5 times that by the former. Here Vl and Vs are the velocities of the dilatational and shear waves, respectively. The agreement between the theoretical and observed values of the attenuation coefficient is much better than that previously obtained by Mason and McSkimin.
The attenuation due to local fluctuations in the density of a medium caused by thermal agitation is also calculated. For solids and liquids this effect is completely negligible. However, for a gas near its critical point, this attenuation is appreciable and rises sharply as the critical point is approached.
Evaluation of a Stereophonic Loudspeaker by Multiple Microphone Arrays
Authors: Carlisle Richard W. , Schwartz Arnold 
Published: September 2005

There is a problem in measuring the sound distribution from a stereospeaker array to correlate the results of anechoic chamber measurements with listening tests in live listening rooms.
One method which is helpful is to measure the pressure at a large number of points in the live-room. A multiple microphone arrangement is described which facilitates such measurements, and its application to a stereophonic speaker system is illustrated.
Scaling Human Reactions to the Sound from Aircraft
Authors: Kryter Karl D. 
Published: September 2005

Studies were undertaken to (determine how “noisy” commercial jet aircraft will sound to people on the ground in comparison to present-day commercial aircraft with reciprocating engines. Three experiments involved the flyover sound made by reciprocating-engine aircraft (a DC-7 and a Super-Constellation) and jet aircraft (a Caravelle, a Comet, and a 707). People were asked to judge the “annoyance” or potential bother-someness of the sounds relative to one another.
It was found that the over-all sound pressure level (“C” scale) and the speech interference level (SIL) of the sounds from the aircraft as measured on the ground, either outdoors or indoors, bear little relation to the judgments. The loudness level in phons, the values obtained with the aid of the “equal listener-response curve” of Miller and Beranek, and over-all sound pressure level “A” scale and “P” scale correlate better with the findings. However, the results of the judgment tests are predicted best when the SPL's of the various octave bands are weighted in a newly prescribed manner. This calculation scheme is based on previously published equal-annoyance contours and the procedures developed by Stevens for calculating loudness level.
Experimental Study of Bone Conduction in Ears with Mechanical Impairment of the Ossicles
Authors: Legouix J. P. , Tarab S. 
Published: September 2005

The cochlear-microphonic potential of guinea pigs was recorded during stimulation by bone-conducted sounds. The amplitude and the phase of the response were measured while the ossicles were altered in various ways.
At low and middle frequencies, fixation of the ossicular chain produces a decrease of amplitude and a phase advance of about 70°, while an increase of the mass yields an increase of amplitude and a phase lag greater than 180°. A progressive increase of the mass, produced by introducing paraffin oil in the middle-ear cavity, yields a progressive variation of amplitude and phase and, at a particular moment, a complete disappearance of the response. Symmetrical results were obtained by altering the intrabullar pressure. All these results are interpreted as showing the participation of several mechanisms contributing to the whole response. At low frequencies a translational mechanism involves two components: one related to the motion of the ossicular chain and the other related to the motion of the perilymphatic fluid. These two components contribute to the whole response according to their amplitude and phase. At higher frequencies a compressional mode of bone conduction, independent of the motion of the ossicles, is responsible for the stimulation. These findings agree with the alteration of bone conduction observed in clinical cases and provide an explanation for the lateralization of the sound source in an ear affected by conductive deafness, as shown in the Weber test. This lateralization may be accounted for by the observed phase shifts.
Minimal Rules for Synthesizing Speech
Authors: Liberman A. M. , Ingemann Frances , Lisker Leigh , Delattre Pierre , Cooper F. S. 
Published: September 2005

It has been found to be extremely difficult to isolate phonemic elements from recorded utterances or to synthesize speech by assembling prerecorded phonemic segments. One reason for the difficulty lies in the fact that the perceptually discrete phonemes are typically combined, and in some cases encoded, into units of essentially syllabic dimensions. As a result, prerecorded elements must, in many cases, approximate syllables, and the synthesis of speech by this means will require a large inventory of recordings. By taking advantage of knowledge about the acoustic cues for speech perception, however, it is possible to write rules for synthesis in terms of phonemes (rather than syllables) and thus reduce considerably the number of separate rules or items needed. Indeed, one can reduce the number of rules still further by writing them at the level of subphonemic dimensions, viz., place and manner of articulation. Several complicating factors make it impossible to achieve an ideal minimum. First, rules or rule modifiers must be added to take care of certain prosodic and positional variations. Failure to do so not only affects naturalness, but also impairs intelligibility, even at the level of segmental phonemes. Second, it is necessary in a few special cases to have different rules for a single consonant phoneme (or a dimension of that phoneme) before different vowels. This reflects the occasionally complex relation between phoneme and articulation on the one hand and sound output on the other; presumably, this complication would not affect the rules of synthesis for an articulatory model.
A system of rules for synthesis framed largely in terms of subphonemic dimensions is described with reference to an example. Words and sentences of rather high intelligibility have been synthesized by such rules.
Pure-Tone Masking
Authors: Small Arnold M. 
Published: September 2005

The influence of one pure tone on the threshold of another was investigated. In contrast to previous experiments, masking in the present experiment was studied by determining the level of the masker necessary to mask a signal as a function of the frequency of the masker. The level and frequency of the signal served as parameters. The general forms of the masking functions are similar to those reported previously, but vary in several details. The maximum masking effect occurred when the frequency of the masker approximated that of the signal. When the masker frequency was greater than that of the signal the slope of the masking function was very steep, 150–280 db/octave depending upon signal level and frequency. This slope tended to be steeper at higher signal levels and, although less marked, also at higher signal frequencies. When the masker frequency was about 0.85 that of the signal an irregularity appeared in the masking curves. The size of this hump increased as signal frequency and level increased. Its frequency location seemed to rule out aural harmonics as a cause and its presence was tentatively related to perception of envelope modulation.
The data are discussed from the points of view of band-pass filter analog and compared to studies of previous investigators. In general the present findings represent an extension of pure tone masking data with wider ranges of stimuli and a different method than those previously used.
Design of Directional Arrays
Authors: Brown John L. , Rowlands Richard O. 
Published: September 2005

From the application of information theory, it is found that for low signal-to-noise ratios, there is no better method of increasing the information content of a signal than to add the outputs of the elements of an array to improve the signal-to-noise ratio. When the signal-to-noise ratio is already high, however, the array should be designed so that independent information is supplied by each element when associated with a reference element.
The possibility of increasing directionality by nonlinear operations is then discussed. In particular, it is shown that, for the noiseless case, a two element array can be made to yield patterns equivalent to those produced by an n-element linear array. Linear maximum directivity arrays (in the sense of Pritchard) may also be synthesized with three omnidirectional elements and a number of nonlinear operations which remains invariant as the order of the equivalent linear army is increased.
Finally linear methods designed to minimize the mean squared error are considered and it is found that array rotation is capable of giving optimum results under certain circumstances.
Search for Physical Correlates to Psychological Dimensions of Sounds
Authors: Solomon Lawrence N. 
Published: September 2005

Twenty passive sonar recordings were ranked by 50 subjects in terms of their aurally perceived (psychological) characteristics on seven different dimensions. Correlations were run between octave band sound pressure level measurements of the sounds and their rank orders on the seven psychological dimensions. Meaningful relationships were found between ranks on certain psychological dimensions and energy concentration within certain octave bands.
Also, an analysis was made of the manner in which the twenty sounds clustered within the space defined by the seven psychological dimensions. Analyses of these sound clusters revealed that the rhythmic beat pattern of the stimulus is a principal attribute upon which sonar men base their judgments of “similarity.”
Absorption of Sound by a Strip of Absorptive Material in a Diffuse Sound Field
Authors: Northwood T. D. , Grisaru M. T. , Medcof M. A. 
Published: September 2005

The random incidence sound absorption coefficient is calculated for a narrow strip of absorbing material set in an otherwise reflecting plane. The assumptions made are that the material is of the locally reacting type, with a real normal admittance. The effect of an imaginary component of admittance is discussed qualitatively.
The results show the increase in absorption coefficient that occurs at small widths due to diffraction. Consideration is also given to the absorption of rectangular patches having both dimensions in the diffraction range. The standard reverberation room measurement of sound absorption is examined.
Experimental Study of the Propagation of Sound over Ground
Authors: Wiener Francis M. , Keast David N. 
Published: September 2005

The attenuation of sound propagated out-of-doors is conveniently separated into attenuation due to spherical divergence and excess attenuation due to atmospheric and terrain effects. This excess attenuation is principally caused by sound absorption in the air, the refractive effects of temperature and wind gradients, by turbulence and the effects of terrain and ground cover. To investigate these effects the propagation of sound over open, level ground, through dense evergreen forests, and between hilltops was studied experimentally in the frequency range between about 300 cps and 5000 cps. Extensive micrometeorological instrumentation was utilized to measure and record the relevant micrometeorological parameters simultaneously with the acoustic data for a wide variety of weather conditions. Data on the attenuation of the mean received sound pressure level as well as on the fluctuations about the mean were obtained and correlated with the state of the atmosphere.
Over open level terrain, the excess attenuation upwind was found to exceed that for downwind propagation by as much as 25–30 db for source and receiver heights of 12 and 5 ft, respectively. Temperature and wind gradients near the ground-air interface largely account for this difference. In hilltop-to-hilltop propagation, wind direction is of secondary importance, and in dense woods absorption and scattering control. Empirical functions were derived for the purpose of estimating the mean excess attenuation as a function of frequency and distance, for a given set of micrometeorological conditions. These charts have been found useful in many practical problems involving the propagation of sound over open level ground.
Damping of Flexural Waves by a Constrained Viscoelastic Layer
Authors: Kerwin Edward M. 
Published: September 2005

For a number of years it has been known that flexural vibrations in a plate can be damped by the application of a layer of damping (viscoelastic) material that is in turn constrained by a backing layer or foil. A common example is the damping tape currently used in aircraft.
This paper presents a quantitative analysis of the damping effectiveness of such a constrained layer. As in the work of H. Oberst the damping is characterized by the loss factor η, which is the normalized imaginary part of the complex bending stiffness of the damped plate.
The calculated damping factor depends on the wavelength of bending waves in the damped plate, and on the thicknesses and elastic moduli of the plate, the damping layer, and the constraining layer. A complex shear modulus is assigned to the damping layer, where all of the energy dissipation is assumed to take place.
Damping factors have been determined experimentally on laboratory test bars for a number of constrained-damping-layer applications for frequencies from about 100 to 4000 cps over a range of temperatures. Gratifying agreement with calculated damping has been found for variations in frequency, temperature, and damped-bar geometry.
On the Diffusion of Sound Waves in a Turbulent Atmosphere
Authors: Lyon Richard H. 
Published: September 2005

The directional and frequency diffusion of a plane monochromatic sound wave in statistically homogeneous, isotropic, and stationary turbulence is analyzed theoretically. The treatment is based on the diffusion equation for the energy density of sound waves, using the scattering cross section derived by Kraichnan for the type of turbulence assumed here.
A form for the frequency wave number spectrum of the turbulence is adopted which contains some pertinent parameters of the flow and is adapted to ease of calculation. It is expected that the assumed spectrum is unrealistic at larger wave numbers. A new approach to the evaluation of the characteristic period of the flow is suggested. This spectrum is then related to the scattering cross section.
Finally, a diffusion equation is derived as a small-angle scattering approximation to the rigorous transport equation. The rate of spread of the incident wave in frequency and direction is calculated as well as the power spectrum and autocorrelation functions for the wave.
Pressure Dependence of Sound Propagation in the Primary Alcohols
Authors: Carnevale E. H. , Litovitz T. A. 
Published: September 2005

Measurements of sound absorption and velocity were made on the ethyl, methyl, n-propyl, and n-butyl alcohols up to a pressure of 2000 kg/cm2. The results showed that both the shear and compressional viscosities of these liquids increased as the pressure increased, the pressure dependence of the compressional viscosity being the smaller of the two. Measurements of the temperature dependence of the absorption in n-butyl alcohol at 2000 kg/cm2 showed that no detectable difference in the activation energies for the two viscous processes was caused by the high pressure.
It was found that the two-state structural relaxation theory proposed by Hall to explain sound absorption in water is inadequate to explain the pressure dependence of sound absorption of the alcohols.
Relaxations in the Attenuation of Single Crystal Lead at Low Temperatures and Their Relation to Dislocation Theory
Authors: Mason W. P. 
Published: September 2005

Measurements of the attenuations of face-centered metals by Bordoni have shown attenuation peaks at low temperatures. By using the measurements of Bömmel on single crystal lead it can be verified that this is a relaxation and values can be obtained for activation energies and frequency terms. It is shown that the measured results correlate well with a relaxation due to the displacement of a dislocation from one atomic line to an adjacent one against the limiting shearing stress of the crystal. The limiting shearing stress measured for four face-centered metals is in good agreement with theoretical calculations of Cottrell.
A higher temperature loss is also measured which increases exponentially with the temperature. It is shown that this term is due to breakaway of the dislocation from its impurity pinning points due to thermal agitation. This breakaway abstracts energy from the vibration and produces a loss independent of the frequency but increasing with temperature since more breakaways occur at higher temperatures. The activation energy of breakaways correlates well with the binding energy of impurity atoms.
The Measurement of Loudness
Authors: Stevens S. S. 
Published: September 2005

This paper reviews the available evidence (published and unpublished) on the relation between loudness and stimulus intensity. The evidence suggests that for the typical listener the loudness L of a 1000-cycle tone can be approximated by a power function of intensity I, of which the exponent is log102. The equation is: L = kI0.3. Intensity here is assumed to be proportional to the square of the sound pressure.
In terms of sones, where 1 sone is the loudness produced by a tone at 40 db above the standard reference level, the equation for loudness L as a function of the number of decibels N becomes: logL=0.03N−1.2.
Otherwise said, a loudness ratio of 2:1 is produced by a pair of stimuli that differ by 10 db, and this relation appears to hold over the entire range of audible intensities.
At low levels of intensity, the loudness of white noise grows more rapidly than the loudness of a 1000-cycle tone, but above the level of approximately 50 db the two loudnesses remain more nearly proportional. The suggestion is made that for all levels greater than 50 db the loudness of continuous noises may be calculated from the equation: logL=0.03N+S, where S is a spectrum parameter to be determined empirically.