bluuebunny/crossref_metadata_2025 huggingface dataset:
REPEATABILITY OF GROUND-TEST NOISE MEASUREMENTS ON AN AIRCRAFT ENGINE
Authors: Thorpe Howard A.
Published: October 2005

Measurement repeatability, accuracy, and effects of elevating both microphones and a JT8D engine are discussed briefly. Also data acquisition and processing techniques are indicated.
Intensity Changes at the Ear as a Function of the Azimuth of a Tone Source: A Comparative Study
Authors: Harrison J. M. , Downey P.
Published: October 2005

Sound intensity of a tone (4, 10, and 20 kHz) was measured at the external auditory meatus as a function of the azimuth (at every 15°) of the sound source. The observations were made under free-field conditions, and man, squirrel monkey, rat, and bat were used as subjects. At 4 kHz, rat and man showed consistent variation of intensity as a function of azimuth. Only irregular variations were obtained in monkey and bat. Interaural-intensity differences (IIDS) at 4 kHz were estimated to be sufficient to support localization of a tone at a minimum angle of 2.1° (rat) and 1.125° (man) from the midline. At 10 kHz, rat, bat, and monkey showed consistent variations of intensity with azimuth of at least 15 dB. IIDs at 10 kHz were estimated to be sufficient to support the localization of a tone at a minimum angle of 1.125° (monkey), 2.0° (bat), and 1.5° (rat) from the midline. At 20 kHz, consistent intensity variations of at least 14 dB were obtained in rat, bat, and monkey. IIDs were estimated as sufficient to support localization at a minimum angle of 1.5° (monkey), 2.25° (bat), and 3.6° (rat).
Chords from Tones Having Stretched Partials
Authors: Slaymaker Frank H.
Published: October 2005

Tones made up of partials having frequencies proportional to NS, where N is the partial number and S is the stretch exponent, have been generated on a digital computer and used to form scales and chords. The scales were constructed with the frequency ratio between “half steps” equal to (21/12)S. Chords analogous to the tonic, subdominant, and dominant were generated for S varying from 0.792481, which compressed the partials by a factor that made the frequency of the fourth partial three times that of the fundamental, to 1.261859, which made the frequency of the third partial four times that of the first. The sensation produced by the stretched chords was consistent with Helmholtz's criterion for dissonance. The quality of the individual tones, however, became more and more strange as the value of S increased.
The Lenis-Fortis Opposition: Its Physiological Parameters
Authors: Malécot André
Published: October 2005

Evidence reviewed in this article indicates that the lenis-fortis feature of consonants is primarily a synesthetic interpretation of magnitudes of intrabuccal air pressure and is conveyed variously in different contexts by the durations of the consonant closure and of the preceding vowel. Variations in magnitude as a function of idiolect, syllabic rate, phonetic context, etc., are also described, and new data from normal speech are presented.
Evaluating Speech-Recognition Work
Authors: Lea Wayne A.
Published: October 2005

Pierce [J. Acoust. Soc. Amer. 46, 1049–1051(L) (1969)] has recently questioned motivations and progress in speech-recognition work. Constructive steps can and should be taken to determine the value of speech communication with computers, the potential for “success,” the value of limited speech recognizers, and the best design of speech-research programs. Speech does offer some advantages for effective man-computer interaction. Since fully versatile speech recognizers are apparently not immediately forthcoming, scientific studies should be made of the actual utility of restricted recognizers. One such study has begun. Pierce's criticisms remind one of the continued need to answer elementary questions of “why” and “how much” in speech-recognition work.
Whither Speech Production?
Authors: Noll A. Michael
Published: October 2005

Research in automatic speech production, like research in automatic speech recognition, seems to be regressing at an ever-increasing rate when compared with the over-all progress of technology. Both speech production and speech recognition involve human beings and perceptual phenomena about which very little information is available. A negative attitude towards either automatic speech recognition or automatic speech production logically must lead to a negative attitude towards the other. Hence, speech research aimed at automating either the recognition or the production of speech will require many years of effort before anything approaching practical results is obtained. The speech process should ultimately be investigated for its own intrinsic merit—not for satisfying man-machine communication needs.
Discrete versus Continuous Space Averaging in a Reverberant Sound Field
Authors: Waterhouse Richard , Lubman David
Published: October 2005

Continuous averaging along a straight line does not always give better results than averaging at discrete points, uniformly spaced at half a wavelength apart along the same path. The continuous average is often a poorer estimate of the true mean than this discrete average. An explanation of this surprising fact is given, in terms of the cross-correlation curve for the sound field, and it is shown that a discrete average can be found that is always better than the continuous average. Averaging in two or three space dimensions is also considered, and the conclusion is reached that a discrete average, being more accurate and easier to obtain than a continuous average, is preferable. Curves are given for the percent probability of the sample mean lying within prescribed bounds of the true mean, for discrete sampling in a limited region in one, two, and three dimensions.
Nonlinear Distortion of Sound Transmitted through an Orifice
Authors: Ingard Uno
Published: October 2005

Previously reported experimental results [J. Acoust. Soc. Amer. 42, 6–17 (1967)] on nonlinear sound transmission through an orifice are compared with the results obtained from a simple theoretical analysis.
Model for Phase Perception of Complex Tones
Authors: Schroeder M. R.
Published: October 2005

Plomp and Steeneken recently published results on the effect of phase on the timbre of complex tones consisting of 10 harmonically related frequency components [J. Acoust. Soc. Amer. 46, 409–421 (1969)]. The (rank order) similarity judgments obtained in triadic comparisons by eight subjects were represented geometrically in a multidimensional space using Kruskal's monotonic scaling procedure. In order to understand the observed effects of phase on timbre, it is assumed that the ear can detect in these comparison tests differences in the degree of amplitude modulation of all triplets of adjacent frequency components falling into the same critical band. Each 10-tone complex is thus characterized by eight amplitude modulation indices (corresponding to the harmonic triplets 1,2,3; 2,3,4; 3,4,5; ⋯; 8,9,10). The Euclidean distances between two stimuli in this multidimensional “modulation space” are found to correlate well with the Euclidean distances in the perceptual space based on the similarity judgments.
Length Optimization for Constrained Viscoelastic Layer Damping
Authors: Plunkett R. , Lee C. T.
Published: October 2005

Viscoelastic materials are used extensively to damp flexural vibrations of metallic structures; it has been known for some time that the energy dissipation due to shear strain in the viscoelastic layer can be increased by constraining it with a stiffer covering layer. In this paper, we will discuss a method for increasing this damping by cutting the constraining layer into appropriate lengths. The analysis for a single layer of this treatment is relatively straightforward. The damping can be increased still further by using several layers; in this case, the analysis is based upon effective complex elastic moduli of an equivalent homogeneous medium. One result found from this analysis is that, if the element length of the constraining layer is optimum, the damping depends primarily upon the stiffness of the constraining layer and the loss coefficient of the viscoelastic material, and only indirectly on the shear modulus of the viscoelastic layer. Experimental data is presented for comparison with the theoretical predictions.
The Effect of Mach Number on the Tuning of an Acoustic Lining in a Flow Duct
Authors: Eversman Walter
Published: October 2005

The propagation of sound in an acoustically lined rectangular duct is investigated for the case when there is a uniform flow in the duct. Solutions are obtained for the sound attenuation in the duct for propagation upstream and downstream in the fundamental mode. It is found theoretically that the frequency at which the peak attenuation for a given lining occurs is increased for downstream propagation and decreased for upstream propagation. Comparisons are made with experimentally determined data and are found to be quite favorable.
Study of Single Units of the Cochlear Nucleus of the Chinchilla
Authors: Mast Truman E.
Published: October 2005

Chinchillas anesthetized with Dial were used for the study of single neurons in the cochlear nucleus (CN), primarily the dorsal cochlear nucleus (DCN). Locations of the neurons were determined histologically. Approximately 80% of neurons in the DCN showed spontaneous activity. Rates were significantly lower in the deepest part of the DCN. A broad range of thresholds to acoustic stimulation was found, but the most sensitive neurons have thresholds comparable to behavioral thresholds. From tuning curves, bandwidths (in octaves) of the neurons were determined, and found to be narrowest at the midfrequencies of the audible range. The rate of adaptation to 125-msec tone bursts was found to be greater in the deeper parts of the DCN. Neurons that were only inhibited and never excited by tone bursts were found only near the junction of the granular layer and the deep plexiform layer. Many of the neurons of the DCN showed some sort of afterdischarge following tonal stimuli.
Opposed Effects of a Delayed Channel on Perception of Dichotically and Monotically Presented CV Syllables
Authors: Studdert-Kennedy M. , Shankweiler D. , Schulman S.
Published: October 2005

We investigated the effects upon perception of delaying one channel during the dichotic presentation of pairs of CV syllables differing in initial stop consonant. Unexpectedly, the time advantage accrued not to the leading, but to the lagging syllable. The situation was exactly reversed with monotic presentation; that is, the advantage accrued to the leading syllable. While the latter result may be interpreted as an instance of peripheral simultaneous masking, the dichotic result would seem to be of central origin.
Laser Heterodyne System for Measurement and Analysis of Vibration
Authors: Eberhardt F. J. , Andrews F. A.
Published: October 2005

The calibration and use of a laser heterodyne system for nonsinusoidal vibration measurements are described. A frequency-shifted beam is heterodyned in a photomultiplier with an unshifted central light beam that has been phase modulated by motion of a reflecting surface. The output of the phototube is passed through a limiter-discriminator receiver, and then through an integrator resulting in a linear reproduction of the surface vibration as long as the frequency-amplitude product is within limits. The linearity and calibration technique has been tested out to a product of 13 kHz × 4700 Å. A minimum amplitude measurement of 3.5 Å was obtained. Measurement of time delay or spatial cross-correlation functions is demonstrated, using two heterodyne detectors.
Precautions with Classical Absorption
Authors: Evans L. B. , Bass H. E. , Winter T. G.
Published: October 2005

When using ultrasonic absorption to study molecular relaxation processes in gases, it has been the practice of our group and many other investigators to assume that the dependence of classical absorption on the frequency/pressure ratio is given (αλ)c1 = kf/ρV2, where k is a proportionality constant, f is the frequency, ρ is the density, and V is the velocity of sound. This assumption neglects the frequency dependence of the absorption due to thermal conductivity and results in a classical absorption that is too low at high f/p. This assumption can lead to serious error whenever classical absorption is an appreciable fraction of the total absorption.
Acoustic-Lining Concepts and Materials for Engine Ducts
Authors: Mangiarotty R. A.
Published: October 2005

A summary is given of a research program to develop acoustic-lining technology for engine ducts. The environment to which linings are exposed in the inlet and duct of a typical turbofan engine installation and the noise spectrum to be attenuated are described. Concepts of acoustic linings and their mechanisms for attenuating the propagation of sound in ducts are discussed, with particular application to turbomachinery. The procedure used for screening and selecting acoustical facing materials for linings is reviewed. A summary is given of the experimental methods employed in this procedure—measurement of the specific flow resistance, the specific acoustic impedance, and of the acoustic absorption coefficient—and a synopsis of the results is made. Suitable materials were evaluated as part of duct linings in a laboratory flow-duct apparatus, simulating an engine-duct environment in which linings were subjected to sound levels up to 155 dB over-all sound-pressure level (SPL) and airflows up to Mach number 0.4. The most important acoustic and geometric characteristics that influence the acoustic attenuation and the results obtained are summarized. The attenuation of linings in a laboratory flow duct and in a full-scale engine are compared. Finally, a description and some results of a theoretical study developed for predicting the attenuation of linings is given and compared with the experimental measurements.
TRANSDUCER FOR MEASURING MANDIBULAR MOVEMENTS
Authors: Sussman Harvey M. , Smith Karl U.
Published: October 2005

A new transducing device that can record the dynamic movements of the mandible during speech is described. The transduction principle is based on the variable resistance changes of strain gauge elements bonded to a flexible metal beam attached to the mandible. The voltage output of the transducer is directly proportional to the lowering and elevation movements of the mandible and can be recorded on a standard oscillograph. The transducer itself is incorporated within a headgear apparatus so that the transducer moves with the head movements of the speaker and thus minimizes artifacts from this source. Calibration procedures and sample records are provided. The transducer is economically constructed and permits on-line flexibility for signal presentation.
Temporal Order in the Perception of Vowels
Authors: Thomas Ian B. , Hill Peter B. , Carroll Francis S. , Garcia Bienvenido
Published: October 2005

Subjects were required to determine temporal order in a continuously repeated sequence of four vowels (/i/, /ɛ/, /a/, /u/). All vowel samples were spliced from the enunciations of one speaker and were controlled for pitch (125 Hz) and true rms intensity. The duration of each vowel segment, T, was varied from 300 to 75 msec; vowel order was randomized for each value of T. In identifying temporal order, listeners achieved near perfect scores for T⩾125 msec; for T⩽100 msec, scores were near chance. Results are compared with those for a similar experiment employing nonspeech sounds.
Pitch Perception of Two-Frequency Stimuli
Authors: Smoorenburg Guido F.
Published: October 2005

Experiments on the pitch of complex tones produced by two frequency components are reported. An exploratory experiment revealed that subjects perceive the pitches of individual part-tones or the stimulus as a whole with a pitch corresponding to about the fundamental frequency. The latter pitch was investigated more thoroughly. In case of adjacent harmonics, the pitch corresponded to the (absent) fundamental frequency. A shift of the frequencies away from such a harmonic situation while maintaining a constant frequency difference resulted in a pitch shift. For higher harmonic numbers, the pitch shift was larger than could be met by current theories. The large pitch shift was explained by taking into account an auditory nonlinearity which generates combination tones of the type f1−k(f2−f1). Sound-pressure level dependence of the pitch shift could be explained in the same manner. When the combination tones were masked, the large pitch shift diminished. With regard to the pitch mechanism, the results suggested that detection of the low pitch of the complex tone requires spectral information.
In-Head Localization of Acoustic Images
Authors: Toole F. E.
Published: October 2005

Listeners placed in an acoustically and visually neutral environment were required to localize sounds presented by means of loudspeakers. Convincing in-head and external image localizations were observed separately and in combination. The amount of in-head localization was found to change substantially and systematically with changes in signal bandwidth and source position. Signal type and center frequency had less effect. It was concluded that small head movements are not the main factor underlying the “externalization” of sounds.
Vowel Spectra, Vowel Spaces, and Vowel Identification
Authors: Klein W. , Plomp R. , Pols L. C. W.
Published: October 2005

Twelve Dutch vowels, each pronounced by 50 male speakers, were analyzed in 18 filter bands comparable in bandwidth with the ear's critical band. By considering the sound levels (in decibels) in these filter bands as dimensions, with a principal-component analysis the 18 dimensions per sound were reduced to four factors which together explain 75% of the total variance. The configuration of the average vowels in the factor space appeared to be highly correlated with their configuration in the F1−F2 formant plane. After matching to maximal congruence, correlation coefficients along corresponding axes were 0.997 and 0.979. Machine vowel identification, based upon the position of the individual vowels in the four-dimensional factor space, resulted (after three pairs of related vowels were grouped together) in 98% correct identifications if correction was applied for personal timbre of the speakers' voices. Ten listeners, to whom the 600 vowels were presented as 100-msec segments, gave 86% correct responses in identifying the intended vowels. The confusions between the vowel types were basis for a multidimensional scaling (Kruskal) to construct a perceptual configuration of the vowels. In four dimensions the solution showed 2.3% stress. Perceptual configuration and factor configuration, maximally matched, had correlation coefficients along corresponding axes of 0.997, 0.995, 0.907, and 0.794, respectively.
Improved Piezoelectric Effect in Polymers
Authors: Edelman S. , Grisham L. R. , Roth S. C. , Cohen J.
Published: October 2005

Improved poling techniques have led to improvement in the piezoelectric activity of bulk polymers. Results now achieved approach the activity of conventional piezoelectric materials such as quartz, and further improvement is anticipated. The measured value of the piezoelectric strain modulus d31 of a length expander bar of polyvinylchloride was 0.6×10−12 m V−1 and the electromechanical coupling factor k31 was 0.6%. The response of a sample as an underwater sound receiver was −112 dB re 1 V/μbar.
Optical Measurements of Ultrasonic Attenuation and Reflection Losses in Fused Silica
Authors: Krischer Charles
Published: October 2005

The ultrasonic attenuation in fused silica was measured by the Bragg diffraction of a 6328-Å He-Ne laser beam; two complementary techniques were used to obtain room-temperature data over the frequency range 200–980 MHz. The frequency dependence of the attenuation is given by f1.97 and f1.98, for longitudinal and transverse waves, respectively. If an exact square-law dependence is assumed, the material loss at 25.0°C can be characterized by the constants B (longitudinal) = (6.1±0.2) × 10−18 dB ⋅ sec, and B (transverse) = (5.7±0.2) × 10−18 dB ⋅ sec, where A (dB/μsec) = B f2. The acoustic-wave reflection losses at the free surface and transducer-bond surface of the sample were evaluated. Although in the former case the loss was negligible, in the latter large reflection losses were observed, in spite of the low conversion efficiency of the transducer. A study of the angular distribution of the acoustic intensity for the generated and reflected beams showed that this loss was mainly dissipative, although a deformation of the plane wavefront was also a contributing factor.
New Ultrasonic Technique for the Determination of the Ratios of Strain-Optical Constants
Authors: Pettersen Howard E.
Published: October 2005

A new ultrasonic technique for the determination of the ratios of strain-optical constants is presented. The new technique makes use of the Raman-Nath theory for the optical diffraction that is produced by a standing ultrasonic wave. It does not require extrapolation to zero sound intensity, which has been the standard procedure for the past 32 years. The intensity of the light in the zero order of the diffraction pattern is observed for light beams which are polarized parallel and perpendicular, respectively, to the ultrasonic wavefront. These data can then be interpreted in either of two ways to determine the ratios of the strain-optical constants. The new technique has been used in studies of various optical glasses and of sodium chloride. In all cases, the results have been in agreement with values obtained by other investigations using old techniques. The numerical values obtained for sodium chloride are |p12/p11| = 1.37, |p44/p11| = 0.088.
Electrical and Mechanical Loading of a Piezoelectric Surface Supporting Surface Waves
Authors: Skeie Halvor
Published: October 2005

The influence of surface loading on the propagation of surface waves on a piezoelectric substrate is analyzed. Both mechanical and electrical loading are described by means of a simple first-order perturbation theory. General formulas for the perturbation of the surface-wave phase velocity caused by deposition of a uniform thin film or by electrical interaction with an adjacent conducting or semiconducting medium are developed. The scattering of surface waves from discrete strips is also analyzed. Results from scattering and wave-propagation analysis are utilized to describe the interdigital surface-wave transducer. An equivalent circuit for a basic transducer element is developed, and the total transducer is analyzed by means of transmission-line theory applied to a network of cascade-coupled elements. The effect of electrode mass loading is specially treated, and the results are compared with measurements made on a Y-cut Z-propagation LiNbO3 crystal.
Ultrasonic Absorption in H2S
Authors: Winter T. G. , Bass H. E.
Published: October 2005

Ultrasonic absorption has been measured in H2S in the temperature range 300°–683°K. These data were analyzed to obtain vibrational and rotational relaxation times. The vibrational collision numbers seem to increase with temperature from 300° to 473°K and then decrease with temperature. This behavior can be explained by the v-r theory of Shields and Burks. The rotational collision numbers compare favorably with thermal transpiration measurements.
Ground Loading from Footsteps
Authors: Galbraith F. W. , Barton M. V.
Published: October 2005

A series of laboratory experiments was conducted to measure the load-time histories of the input to the ground from footsteps. The purpose of the experiments was to obtain basic input data as part of a study to improve detection of intruders by sensing seismic signals from footsteps. Three subjects, whose weights varied from 115 to 250 lb, made successive tests at rates ranging from a slow walk (almost a sneak) to running. Similar tests were run with shoes and without shoes. The test surface was varied from hard to sandy for different series of tests. Important parameters were the weight of the subject and the rate of walking. The type of footwear and the surface did not affect greatly the load-time histories.
A Tone-Burst Technique of Sound-Absorption Measurement
Authors: Powell John G. , Van Houten John J.
Published: October 2005

The measurement of a normal-incidence sound-absorption coefficient of materials by application of a tone-burst technique is described. In this technique a narrow-bandwidth sinusoidal pulse is propagated down a tube and reflected from the sample. These data, when combined with similarly obtained tube-calibration data, yield the absorption coefficient. The method has been used to obtain absorption-coefficient data on several absorbers over the frequency range from 500 Hz to 10 kHz, at peak sound-pressure levels to 165 dB.
Acoustical Beam Patterns for Bats: Some Theoretical Considerations
Authors: Strother G. K. , Mogus M.
Published: October 2005

Acoustical beam patterns for emission from several different bats are calculated assuming a piston source in an infinite baffle, both as single and as double emitters. The calculated beam patterns agree well enough with experimental values available in the literature to justify the assumptions used. For those bats which possess no facial appendages to serve as a baffle, the simple acoustical model does not work, as anticipated. The calculated beam patterns are for fixed frequencies in the examples used; however, some aspects of frequency modulated beams are briefly discussed.
A Novel Technique for Measuring the Strength of Liquids
Authors: Apfel Robert E.
Published: October 2005

A novel technique has been effectively utilized in studying the properties of liquids under conditions that are not ordinarily accessible. This technique involves the use of an acoustic standing-wave field established in a column of one liquid in order to trap an immiscible droplet of another liquid. In the experiment reported here, a filtered ether droplet suspended in filtered glycerine was superheated and acoustically stressed until the combination produced an explosive liquid-to-vapor phase transition. The experiment was performed under atmospheric conditions at which the normal boiling point of ether is 35.6°C. The measured tensile strength varied linearly from 17 bars at 130°C to 0 bars at 146°C. Previous measurements of the tensile strength of liquids have not come within a factor of 2 or 3 of the theoretical predictions based on homogeneous nucleation theory, a theory which describes the vaporization conditions for pure liquids. The results reported here are in good agreement with that theory. This novel agreement is attributed to the ability to obtain pure liquid samples by utilizing small (0.5-mm-diam) filtered droplets.
Propagation of Sound through a Variable-Area Duct with a Steady Compressible Flow
Authors: Eisenberg Norman A. , Kao Timothy W.
Published: October 2005

The equations governing the progagation of sound in a nonconstant area duct with a one-dimensional fluid flow are derived by a linearizing perturbation technique. The governing equations are transformed successively into two decoupled linear ordinary differential equations with a variable coefficient. By the appropriate choice of duct shape, the variable coefficient is made constant. The duct shape chosen is semi-infinite, diverging from the sonic throat. Solutions are obtained for several choices of the parameter ωL/2as, which relates frequency, duct shape, and speed of sound. The solutions exhibit standing-wave characteristics and reveal certain aspects of energy transfer between the mean flow and sound. The study bears on noise growth and decay in the input and output ducts of certain fluidic amplifiers.
Beam Behavior within the Nearfield of a Vibrating Piston
Authors: Zemanek Joe
Published: October 2005

A numerical investigation of the nearfield region of a vibrating piston was conducted. While existing literature is not exactly clear about how close to a transducer a regular beam pattern is formed, the results of this investigation show the limits of operation one can expect. From one interpretation of literature, a −3-dB beam with a minimum spot size equal to the transducer diameter would be expected to form beyond an axial distance z = 3.89 a2/λ. This investigation shows that such a beam forms at z = 0.75 a2/λ and has a minimum spot size equal to one-quarter the transducer radius. These results are verified for transducers with a/λ's ranging from 1 to 20 and can be extended with confidence to higher a/λ's. Similar results are also obtained for −1.5-, −4.5-, −6.0-, −7.5-, −9.0-, −10.5-, and −12-dB beams.
Variable-Focus Liquid-Filled Hydroacoustic Lens
Authors: Knollman G. C. , Bellin J. L. S. , Weaver J. L.
Published: October 2005

A large fluid lens with accompanying reservoir and pump arrangement is described, with emphasis on its underwater acoustic-imaging application. Pertinent properties are cited of the neutrally buoyant lens fluid, the elastomeric containment membranes, and the composite lens. The liquid-filled lens potentially provides better over-all acoustic transmissivity than does a comparable solid lens and has an equivalent acoustic refractive index. Focusing, achieved without physical motion of the lens proper, occurs in a manner analogous to the operation of the human eye. Introduction or removal of fluid changes the curvature of the lens-membrane surfaces. Theoretical consideration reveals the stretched-membrane surface configuration to be approximately spherical. Thus, standard spherical lens equations are combined with appropriate mensuration formulas to obtain lens calibration equations. A hydroacoustic image taken with the liquid lens is displayed. This image is compared with that formed under identical circumstances by means of an equivalent Lucite lens. Beamwidth and spherical aberration of the fluid lens are discussed. A field stop for use with the liquid lens and a technique for immunizing the lens to water-wave action are noted.
Acoustic Spectra from Turbulent Jets
Authors: Meecham William C.
Published: October 2005

One of the interesting and important problems involving turbulent jets is that of determining the spectrum of the radiated sound. This has proved to be a difficult theoretical problem because the space-time correlation of the velocity is central in the prediction of such sound characteristics. In this work, the following assumptions are used in the development. First, it is supposed, as is often the case in turbulence measurements, that the turbulent fluid has approximately Gaussian statistical characteristics. Then, it is supposed that the space-time characteristics for the needed second-order velocity correlation can be obtained by assuming that the fluid is approximately in “frozen flow.” From these assumptions, the higher-frequency sound-power spectrum is obtained in terms of an integral over the turbulence energy spectrum. For the familiar energy spectrum k−5/3, it is found that the sound spectrum behaves like ω−4/3. This is flatter than most measurements. A measured frequency spectrum of ω−3 would be obtained from an energy spectrum k−5/2.
Large-Amplitude Pulse Propagation—A Transient Effect. II
Authors: Moffett Mark B. , Westervelt Peter J. , Beyer Robert T.
Published: October 2005

The generation of transient signals by the propagation of large-amplitude pulses has been investigated. Measurements of the transient signal along the axis of propagation of 10-MHz pulses in carbon tetrachloride confirm the validity of the theoretical treatment of Berktay [J. Sound Vibration 2, 435–461 (1965)]. Data are also presented for the angular dependence of the transient signals generated by 20-MHz pulses in water.
On the Coupling Loss Factor in Statistical Energy Analysis
Authors: Crandall Stephen H. , Lotz Robert
Published: October 2005

In some applications, coupling loss factors can be estimated either by using wave-transmission methods or by using natural frequency-shift methods. It is demonstrated that the two procedures give essentially the same results for a particular system. This is in contrast with the result given in a recent note which exhibited a fivefold discrepancy between the methods. An explanation for that discrepancy is proposed.
Simulation of Multivariate and Multidimensional Random Processes
Authors: Shinozuka M.
Published: October 2005

Efficient and practical methods of simulating multivariate and multidimensional processes with specified cross-spectral density are presented. When the cross-spectral density matrix of an n-variate process is specified, its component processes can be simulated as the sum of cosine functions with random frequencies and random phase angles. Typical examples of this type are the simulation, for the purpose of shaker test, of a multivariate process representing six components of the acceleration (due to, for example, a booster engine cutoff) measured at the base of a spacecraft and the simulation of horizontal and vertical components of earthquake acceleration. A homogeneous multidimensional process can also be simulated in terms of the sum of cosine functions with random frequencies and random phase angles. Examples of multidimensional processes considered here include the horizontal component f0(t,x) of the wind velocity perpendicular to the axis (x axis) of a slender structure, the vertical gust velocity field f0(x,y) frozen in space, and the boundary-layer pressure field f0(x,y,t). Also, a convenient use of the present method of simulation in a class of nonlinear structural vibration analysis is described with a numerical example.
Ultrasonic Absorption in Pure Methylcyclohexane
Authors: Tannaka Yasuaki
Published: October 2005

The ultrasonic absorption in pure methylcyclohexane was measured in temperatures from 20°C to 60°C. The temperature dependence of μmax disagrees with that extrapolated from high-temperature experiments by Piercy and Subrahmanyam [J. Chem. Phys. 42, 4011 (1965)], but rather agrees with that derived by Pedinoff [J. Chem. Phys. 36, 777 (1962)].
Impedance-Tube Measurements of Sound Velocities in Coated Samples
Authors: Eriksson L. J. , Higgs R. W. , D'Amico P .M.
Published: October 2005

The change in the measured sound velocity due to coatings on samples placed in impedance tubes is examined from an experimental and a theoretical viewpoint. The effect of changes in the sample radius and the wavelength on the velocity is studied with the aid of a digital computer. The asymptotic values of the modes are identified. The sound velocity, measured for a typical plastic surrounded by a water capillary and a polyurethane coating is compared to the above theory for various sample diameters.
A SCHLIEREN SYSTEM USED FOR MAKING MOVIES OF SOUND WAVES
Authors: Neubauer Werner G. , Dragonette Louis R.
Published: October 2005

A schlieren system has been used to produce motion pictures of acoustic wave interactions with cylinders. Details of the system are described.
Measurement of the Two-Click Threshold
Authors: Leshowitz Barry
Published: October 2005

Observers were asked to discriminate between a pair of 10-μsec pulses and a single 20-μsec pulse having the same total energy. The independent variable was the time, ΔT, between the two 10-μsec pulses. The stimuli were also presented as elements in a periodic pulse train. The ΔT required for resolution of two clicks (two-click threshold) was 10 μsec. Whereas the addition of a steady background noise produced a remarkably small change in the magnitude of the two-click threshold, performance deteriorated markedly when the pulses were low-pass filtered. It appears that discrimination of slight changes in the energy spectrum of the two transient signals, especially in the high-frequency region (8000 Hz and above), underlies the ear's sensitivity to a temporal discontinuity.
Transformed Up-Down Methods in Psychoacoustics
Authors: Levitt H.
Published: October 2005

During the past decade a number of variations in the simple up-down procedure have been used in psychoacoustic testing. A broad class of these methods is described with due emphasis on the related problems of parameter estimation and the efficient placing of observations. The advantages of up-down methods are many, including simplicity, high efficiency, robustness, small-sample reliability, and relative freedom from restrictive assumptions. Several applications of these procedures in psychoacoustics are described, including examples where conventional techniques are inapplicable.
Pattern Reversal in Auditory Perception
Authors: Ptacek Paul H. , Pinheiro Marilyn L.
Published: October 2005

Perception of auditory patterns based on an intensity difference was tested in 30 normal subjects under binaural, monaural, and dichotic listening conditions. Each auditory pattern was made up of three temporally spaced white-noise bursts involving two elements, i.e., “Soft” (S) and “Loud” (L). Patterns included SLS, LSL, LLS, SSL, LSS, and SLL. The loud element in the patterns remained at a constant intensity throughout, with the soft elements attenuated from 5 to 20 dB in different sets of patterns. Patterns were presented at 50 dB SL. Subjects needed a 10-dB intensity difference within a pattern in order to recognize it correctly half the time, although the just noticeable difference (jnd) for white noise is about 0.5 dB. This seems to indicate that the pattern recognition task is a higher auditory function than simple discrimination of intensity differences. An unexpected finding was a large number of complete pattern reversals or mirror images which accounted for 30%–40% of errors across listening conditions and intensity-difference levels. Symmetrical patterns were more commonly reversed than asymmetrical patterns. It is suggested that reversals of auditory patterns may occur in a manner similar to figure and ground reversal in vision.
On the Efficiency of Psychophysical Measurement
Authors: Taylor M. M.
Published: October 2005

A previously proposed upper bound on the performance of psychophysical techniques that attempt to determine points on psychometric functions is shown to be a least upper bound. The existence of a realizable technique (the Robbins-Monro process) which asymptotically attains the performance of the proposed ideal shows that this ideal provides an appropriate basis from which to calculate the absolute as opposed to relative efficiency of real psychophysical measurement techniques. The concept of incremental efficiency is introduced. It is shown to be useful in analyzing the performance of measurement techniques when the initial uncertainty of the estimate, often ignored in simulation studies, is neither infinite nor zero, and to permit independent assessment of the efficiency of separate portions of a measurement process.
Effect of Material on Flute Tone Quality
Authors: Coltman John W.
Published: October 2005

Three keyless flutes of identical internal dimensions were made of thin silver, heavy copper, and wood, respectively. They were played out of sight of musically experienced observers, who were asked to determine only whether tones were alike or different. No statistically significant correlation between the listeners' scores and the material of the instrument body was found. Flutists who played the flutes, using an arrangement to eliminate visual or tactile clues, were unable to identify again a previously selected instrument.
Underwater Sounds of Monodon (Narwhal)
Authors: Watkins William A. , Schevill William E. , Ray Carleton
Published: October 2005

Field recordings of underwater sounds of the toothed whale Monodon monoceros exhibit consistent characteristics not noted in other odontocetes. The sounds were mostly narrow-band regularly spaced, and often high-frequency (to 24 kHz). The fundamentals of individual sound pulses ranged from 1.5 to 24 kHz. Both clicks (short pulses produced at repetition rates up to 300/sec) and tones (to 0.1-sec duration) were noted.
Comments on “Contralateral Remote Masking and the Aural Reflex” [K. Gjaevenes, S. Gran, and Ö. Rollag, J. Acoust. Soc. Amer. 46, 918–923 (1969)]
Authors: McRobert H.
Published: October 2005

Some contralateral remote masking results are quoted, which were obtained using a continuously variable delay time between the masking and masked pulses. The agreement between these results and those of Gjaevenes et al. [J. Acoust. Soc. Amer. 46, 918–923 (1969)] is outlined. Finally, some of their conclusions are examined in the light of the available evidence.
An Electromagnetic Method for Transducing Jaw Movements during Speech
Authors: Hixon Thomas J.
Published: October 2005

A new method for transducing movements of the mandible is described. The equipment employed includes a three-coil magnetometer system that enables real-time recording of jaw movements without encumbrance to natural articulation. Theoretical principles underlying the method are discussed, as are procedures for using and calibrating the equipment. Examples of one- and two-dimensional measurements are presented, the latter being related to displacement pathways followed during nonspeech gestures of the mandible. Beyond the specific method described, it is concluded that magnetometers have attractive potential as a research tool in speech physiology.
Classification of Russian Vowels Spoken by Different Speakers
Authors: Lobanov B. M.
Published: October 2005

The problem of speaker normalization is investigated for classifying the Russian vowels. The known methods of normalization of formants F1 and F2 which make their normalized values F1N and F2N invariant to compression or expansion and to parallel shift are mentioned. A new statistical method of normalization is then suggested. All of these methods are compared using an index of normalization quality (η). The result of the comparison shows that the normalization suggested in this letter has the largest index, not only on the average but also for each individual vowel pair. The procedure of classification of the Russian vowels using a self-normalized formant plot is shown at the end of the letter.
On the Dynamic Behavior of a Cable System in a Recovery Operation
Authors: Laura Patricio A. , Goeller Jacques E.
Published: October 2005

The present study deals with an experimental and analytical investigation on the behavior of a cable system in the case of salvage recovery of objects embedded in ocean sediments or handling structures placed on the bottom of the ocean. Steady-state and transient vibrations of the system are considered. The possibility of “snap” loads in the system is studied and some conclusions of practical interest are drawn.
Optimum Frequency for Detection of Acoustic Sources in the Upper Atmosphere
Authors: Procunier R. W. , Sharp G. W.
Published: October 2005

Frequency-selective detection of acoustic sources in the upper atmosphere is shown to offer advantages over a broad-band detector in improving signal-to-noise ratio. A model for an optimum frequency is developed using simplified assumptions: i.e., a source with a Fourier spectrum of uniform amplitude; attenuation by absorption during propagation; local turbulence as the noise source. An optimum frequency is found where the signal-to-noise ratio is maximum as a function of altitude. Experimental evidence confirms that a peak in the signal-to-noise ratio exits for acoustic sources in the upper atmosphere.
Propagation of Fan Noise in Cylindrical Ducts
Authors: Bolleter Ulrich , Chanaud Robert C.
Published: October 2005

The propagation of random sound in a cylindrical duct has been treated theoretically. The conditions under which the simple wave equation applies to the transmission of sound generated by industrial air-moving devices is made explicit. The acoustic forcing function and termination conditions are discussed extensively as well as the structure of the sound field in the duct. Equations for the power spectral density and pressure cross-spectral density are derived in order to define the problems associated with deducing sound power, given sound pressure at two points. The results suggest that an anechoic termination is almost mandatory and that the modal spectra must be known, if accurate measurements are to be made. A number of simplifications to the theory were tested experimentally and found to apply. Modal spectra were measured and were used to compute sound power and predict pressure measurements. The predicted and observed were found to be within 1 dB, suggesting that a practical means for measuring ducted-fan sound power can be found.
Elastic Constants of D2O Ice and Variation of Intermolecular Forces on Deuteration
Authors: Mitzdorf U. , Helmreich D.
Published: October 2005

The elastic constants of D2O ice have been measured between 0° and −140°C. From these data and the elastic constants of H2O ice, the molecular force constants—K for change of bond length and G for change of 0⋯0⋯0 angle—have been calculated. K and G show a similar temperature dependence as the elastic constants; their absolute values enlarge on deuteration. For comparison, values of K and G calculated from infrared data are given.
Cube-Resonance Method to Determine the Elastic Constants of Solids
Authors: Demarest Harold H.
Published: October 2005

The Rayleigh-Ritz method of eigenvalue approximation is used to obtain a solution for the free vibrations of an elastic solid. The resonant frequencies of an isotropic cube, calculated by this method, agree with the frequencies of the Lamé modes, for which an exact solution is possible, up to eight significant digits. Experimental measurements of the 13 lowest-frequency modes of a cube of fused quartz are all within 0.5% of the results computed by using the elastic constants determined by another method. These constants differ from the elastic constants determined directly from the experimental frequencies by less than 0.2% for the shear modulus and by less than 0.003 for the value of Poisson's ratio. The cube-resonance method of elastic constant determination is also applicable to substances of more general crystallographic symmetry.
The Time-Dependent Force and Radiation Impedance on a Piston in a Rigid Infinite Planar Baffle
Authors: Stepanishen P. R.
Published: October 2005

An approach is presented to compute the time-dependent force acting on a piston in a rigid infinite planar baffle as a result of the specified velocity of the piston. The approach to computing the force is applicable to both sinusoidal and nonsinusoidal velocity pulses and is valid for all piston shapes. The approach, which is based on a Green's-function solution to the time-dependent boundary value problem, utilizes a transformation of coordinates to simplify the evaluation of the double surface integrals. An impulse response function is defined such that the time-dependent force can be obtained by differentiating the convolution of the impulse response and piston velocity time functions. A closed-form expression for the impulse response of a circular piston is derived and discussed. Numerical results for the impulse response and the forces on large square pistons resulting from sinusoidal piston velocities are then presented and discussed to compare the transient and steady-state behavior of the forces. Finally, an approach is presented to compute the radiation impedance as a function of normalized frequency from the impulse response data, and the approach is used to obtain the normalized radiation resistance and reactance for square pistons.