bluuebunny/crossref_metadata_2025 huggingface dataset:
Using Time to Identify Noise Sources in Data-Processing Machinery
Authors: Peterson Roger H.
Published: November 2005

An important aspect of noise reduction is identifying and estimating the significance of various sources. Two important procedures for this work include spectrum analysis and using probe-type microphones. A third approach is to use time. If noise-time cycles are long, commercial equipment may be used for the analysis, but, for high-speed impacting machinery, this process is reduced to observation of an oscilloscope display of microphone output versus time. Unfortunately, the peak observed on the screen may be significantly different than the rms value and differ even further from the objection-ability which is dependent on frequency. Techniques to overcome these limitations are described, techniques that have been extremely useful in quantitatively identifying noise sources in data-processing machinery. The approach presently used allows plotting of instantaneous rms level and projected objectionability versus time, as well as providing for identification of sources. A “back-door” approach for accomplishing this same end more directly and, which will be compatible for other types of analysis equipment, is now being evaluated.
Techniques for the Control of Transformer Noise
Authors: Gordon Colin
Published: November 2005

Power-transformer noise is a problem of concern both to the electrical-supply industry and to the transformer manufacturer. The former has to deal most frequently with potential or existing on-site complaints, which often call for total enclosure of the noisy unit. The manufacturer, on the other hand, is more interested in reducing the noise level of the transformer itself and must look towards the source of noise and at the paths whereby the source energy reaches the transformer surface. He is also frequently interested in the design and manufacture of prefabricated lightweight enclosures, which form an attractive alternative, in many situations, to more-conventional masonry enclosures. In this paper, some potentially helpful methods of noise control are discussed. A model experimental study is described that was undertaken by a British firm of transformer manufacturers to determine the principal factors affecting transformer-enclosure performance, in particular the performance of close-mounted enclosures.
Parameters of Lip Position
Authors: Fromkin Victoria A.
Published: November 2005

Three kinds of data were used in an attempt to determine the parameters of characteristic lip positions in a range of American English vowels: (1) standardized simultaneous frontal and lateral photographs; (2) lateral x-rays; (3) plaster casts of a subject's lips. Among the measurements taken were the following: (1) distance between the corners of the mouth (width); (2) height of the opening on the midline; (3) area as measured on a frontal view; (4) protrusion; (5) retraction of the corners of the mouth. As a check on the consistency of measurement and performance, these data were used to compare a single subject's production of the set of vowels on a number of occasions. Comparisons with other subjects were also made. The interrelationships of these variables are discussed. [Investigation partially supported by Public Health Service, U. S. Department of Health, Education, and Welfare, grant No. NB-04595.]
On the Derivation of Area Functions and Acoustic Spectra from Cinéradiographic Films of Speech
Authors: Heinz John M. , Stevens Kenneth N.
Published: November 2005

The objective of this paper is to determine whether it is possible to derive a transformation, valid for a given talker, for determining area functions corresponding to any speechlike articulatory configuration from measurements on lateral cinéradiographic films of the vocal mechanism. A tentative set of rules for accomplishing this transformation has been established. The rules are specified largely in terms of a series of functions that relate the cross-sectional area at each of a number of points along the vocal tract to linear dimensions determined from the x-ray films and incorporate the effects of jaw and velum positions. The validity of area functions derived through use of these rules has been tested by comparing formant frequencies measured for the corresponding utterances with those calculated (by digital computer) from the area functions. Webster's horn equation is taken as the basis for calculating formant frequencies from area functions. The corresponding spectra are also computed for comparison with the measured spectra of the speech sounds, making certain assumptions regarding source spectra and locations and resonance bandwidths. In general, agreement between computed and measured formant frequencies by the two methods is within a few percent for the first three formants for a variety of consonant and vowel configurations. [Work supported in part by the U. S. Army Signal Corps, U. S. Air Force Office of Scientific Research, and U. S. Office of Naval Research; in part by the National Science Foundation (grant G-16526), the National Institutes of Health, U. S. Department of Health, Education, and Welfare (grants MH-04737-03 and NB-04332-01), and the National Aeronautics and Space Administration (grant NsG-496); and in part by the U. S. Air Force (ESD) under contract AF19 (628)-3325.]
Control Language for Experimental Speech Synthesis
Authors: Dennis Jack B.
Published: November 2005

A language has been designed for the description of utterances to be synthesized through computer control of analog models of speech mechanism or through digital-computer simulation. A compiler for the language translates an utterance description into the time-ordered sequence of events that must occur in the model. Some of these events direct the generation of control signals for the parameters of the model. Other events control the timing of pitch pulses. The language and its compiler are designed for on-line use of a computer in experimental speech synthesis, and they permit the experimenter to specify an utterance, observe it, and adjust parameters for further trials until the desired synthesis is realized. The language and its compiler are described in the talk, and several examples are given to illustrate its use. [Work supported in part by the U. S. Army Signal Corps, the U. S. Air Force Office of Scientific Research, and the U. S. Office of Naval Research; in part by the .National Science Foundation (grant G-16526), the National Institutes of Health, U. S. Department of Health, Education, and Welfare (grants MH104737-03 and NB-04332-01), and the National Aeronautics and Space Administration (grant NsG-496); and in part by the U. S. Air Force (ESD) under contract AF19(628)3325.]
On the Applications of Distinctive Features to Speech Recognition
Authors: Hemdal John F. , Hughes George W.
Published: November 2005

The value of a distinctive-feature description of the speech process at the level of linguistic studies involving grammar, syntax, morphology, phonology, etc., has already been demonstrated. The value of the distinctive-feature approach to automatic-speech recognition, compared to other descriptions of the speech process, has heretofore been only partially examined. A computer-recognition scheme, based on the goal of tracking the distinctive features of speech, is presented. The program provides a complete vowel-recognition logic, which compares favorably with the behavior of a panel of listeners when both are presented with the speech of a single speaker. Methods are presented by which single vowel, diphthong, and possible triphthong recognition is produced from the speech spectral data. Details are given on the recognition of the short or lax vowels for which formant transitions and variations are often extreme. Also discussed is the possible effect of speech tempo on a proposed tense/lax boundary and its implications. Preliminary evidence suggests that Fant's neutral vowel may take on fundamental phonetic as well as articulatory significance. [Research reported in this paper sponsored by the U. S. Air Force Cambridge Research Laboratories, Office of Aerospace Research, under contract AF 19(628)305.]
Machine Recognition of Mandarin Monosyllable
Authors: Li Kung-Pu
Published: November 2005

An analysis of the syllable structure of Mandarin Chinese has been done that leads to the design of a feasible mono-syllable recognition system for the language. The system depends on a proper segmentation to simplify the decision process. The system utilized the distributional constraints of the segments in the language for more-reliable results. A simple coding process for diphthongs has been proposed. The spectrum data were processed by a high-speed speech analyzer. Formant-tracking and decision processes were programmed into an IBM-7094. Data from two speakers, each pronouncing 360 distinct monosyllables, have been studied in connection with evaluating the effectiveness of the system and the possibility of implementing it on a real-time basis. The methods and results of the system and the experiments are discussed. [Work partly supported by the U. S. Office of Naval Research grant no. NONR-495(27), and partly supported by the Department of Electrical Engineering of The Ohio State University.]
Mach-Zehnder Type of Ultrasonic Interferometer
Authors: Turner W. R.
Published: November 2005

The potential of a Mach-Zehnder type of ultrasonic interferometer is explored for applications requiring the simultaneous measurement of velocity and attenuation over a range of frequencies and to a degree of precision unobtainable with existing techniques. Constructional and performance details are given for an experimental ultrasonic interferometer developed under ONR sponsorship for use in microbubble studies. This provided relative attenuation and velocity comparisons at three fixed frequencies of 1.635, 4.928, and 8.222 mc/sec to relative precisions of 0.12 dB/m and 0.05 m/sec, respectively, for measurements spanning 700 h time.
Design of a 3-Gc/sec Hypersonic Interferometer for Liquids
Authors: Stewart James L. , Stewart Ellen S.
Published: November 2005

A hypersonic interferometer for liquids at room temperature has been designed employing the aluminized quartz-cavity resonator developed by the authors [J. Acoust. Soc. Am. 35, 931–922, 975–981 (1963)]. The problems discussed include: the optimal design of the electromagnetic cavity, the production of very thin and plane-parallel quartz crystals [Signal Corps Eng. Labs. (USAELRDL), Ft. Monmouth, N.J. Rept. E-1080 (1951)], the aluminizing of the crystals, the rigid mounting of the crystals, the capacity coupling of the aluminum film to the cavity, the container for the liquid, and the design of the acoustic reflector that is also to be used to optically determine alignment and displacement. A reentrant reflector was designed to reconcile the conflicting requirements that the diameter of the reflector be kept small to minimize the viscous resistance to fluid flow and be kept large to permit optical alignment to 110 wavelength.
Sound Propagation in Two-Phase Fluids
Authors: Karplus Henry B. , Clinch J. Michael
Published: November 2005

The complex sound-propagation constant is calculated for liquid-vapor mixtures. At low frequencies, the sound velocity is a function of the mixture quality or relative masses of the phases. At intermediate frequencies, the propagation depends on the sound frequency and also on the size distribution of the discontinuous phase. At high frequencies, the propagation is essentially a function of the predominant phase. Calculations at intermediate frequencies lead to complicated expressions for the wave-propagation constants. This is true even for an idealized 2-phase fluid as, for example, a vapor fog containing uniformly dispersed droplets of equal size. Simplified expressions taking into account drag and heat transfer between the phases yield estimates of the relaxation times or time constants associated with these processes. These time constants determine the region of frequency and aggregate sizes of the individual phases in which these parameters have little effect on the propagation constants. [Work supported by the National Aeronautics and Space Administration.]
Temperature and Pressure Dependence of the Free Volume of Liquid Glycerol
Authors: Slie Warren M. , Litovitz Theodore A.
Published: November 2005

Measurements of ultrasonic velocity were made in liquid glycerol as a function of temperature up to a pressure of 3000 arm. From these data, the compressional part of the relaxational modulus Kr was calculated as a function of pressure and temperature. Using a 2-state liquid model, an expression for Kr, is obtained in terms of the total free volume present in the liquid. Combining this theoretical result with the ultrasonic data allowed us to calculate the free volume of glycerol as a function of temperature and pressure. These free-volume data are in excellent agreement with the measured temperature and pressure dependence of the density of glycerol. It appears that ultrasonic-relaxation data can be a useful method of calculating the free volume of liquids.
On Conformational Analysis and the Ultrasonic Relaxation in Methyl Cyclohexane
Authors: Piercy J. E.
Published: November 2005

A plethora of mutually contradictory conclusions has been drawn from ultrasonic measurements in the 6 separate investigations of the relaxation in methyl cyclohexane recorded in the literature. A critical study now reveals that all the measurements can be reconciled with a single mechanism, the interconversion of axial and equatorial conformations, and values of approximately 3.0 kcal/mole, 3.0 e.u., and 11 kcal/mole for the difference in enthalpy, difference in entropy, and barrier between axial and equatorial conformations respectively. Although the axial-equatorial reaction plays a central role in the conformational analysis much used now in the chemistry of alicycli systems, it has never been possible to measure these energy and entropy differences directly in as elementary a molecule as methyl cyclohexane. As a result, the model for the sources of strain energy in alicyclic molecules, which is used to estimate the vital differences in energy between conformations, is largely without direct verification. The considerable disparity between these estimates for methyl cyclohexane and the present measurements is analyzed, and modifications are proposed to make the model both more accurate and physically reasonable.
Classical Ultrasonic Absorption in Liquid Gallium
Authors: Hunter Joseph L. , Hovan Kenneth S.
Published: November 2005

Because of the high values of wave velocity and density and the low value of viscosity in gallium, the Stokes-Kirchoff value of α/f2 is only 1.6×10−17 sec2 cm−1, of which approximately 75% is due to the thermal term. Measurements at 270 Mc/sec over a temperature range of 30°–60°C have checked this value to an accuracy of 2%. Velocity measurements were also carried out over this range. The accuracy of the measurement and the certainty of the physical constants entering into the classical value are discussed. The measurement was made over an inch of path length, and the attenuation in this distance was approximately 29 dB. As far as is known, this is the lowest value of ultrasonic absorption occurring in liquids. [Work supported in part by the U. S. Office of Naval Research.]
Comparison of Time Delay and Phase Shift of a Narrow-Band Noise Signal in Binaural Signal Detection
Authors: Rilling Mark E. , Jeffress Lloyd A.
Published: November 2005

The signal employed in most binaural-masking studies is a tone. In the present experiment, signal is Gaussian noise passed through a 50-cps filter centered at 500 cps. The masker is broad-band noise. The signal was shifted in phase by 30° steps between 0° and 180° and delayed by corresponding steps between 0 and 1 msec. The conditions using a noise signal are compared with the same conditions in which a 500-cps tone is the signal. Data were obtained by a 2-interval forced-choice method. The signal levels required for a d′ of 1.5 were determined for all conditions, using a method developed by Jeffress. These signal levels are plotted as masking-level differences (MLD's) relative to the homophasic condition and permit comparison of the various conditions. The functions relating phase shift and time delay of the noise and tonal signals to the size of the MLD are similar in shape. The MLD increases rapidly as the phase shift or time delay increases. Differences in the size of the MLD between corresponding and phase-shift time-delay conditions are small for the noise signal and are approximately equal to the MLD's obtained with a pure tone.
General Prediction Relating Yes-No and Forced-Choice Results
Authors: Green David M.
Published: November 2005

One reason for developing detailed models of the detection or discrimination process is to provide a means of predicting performance in a variety of test situations, thereby permitting a psychoacoustic theory that is not bound to any single psychophysical method. Two general methods are often used to study discrimination or detection processes. In the Yes-No task, a single observation interval occurs; the signal is either presented or not and the subject says that Yes—he hears the signal or No—he does not. In the forced-choice task, several observation intervals occur; the signal is presented in only one of them and the subject indicates the interval in which he believes the signal has occurred. It can be demonstrated that a number of psychophysical models (e.g., threshold, detection theory) all agree in predicting the same relation between the accuracy of the judgments in the forced-choice task and the area under the Yes-No ROC curve. (The ROC curve is a plot of false-alarm rate versus hit rate for different criterion values.) For example, in the 2-alternative forced-choice task, all models agree that the percent correct is equal to the area under the Yes-No ROC curve. [Research sponsored under a grant from the National Aeronautics and Space Administration, NASw-676.]
Model Study of Signals Reflected from a Wind-Driven Surface
Authors: D'Antinio R. A. , Hill R. F.
Published: November 2005

Underwater acoustic-communication experiments are being conducted in a 12×4×4 model tank equipped with a remote-controlled transducer-positioning system and a “sea-state” generator. The model tank is being used so that any individual acoustic path may be investigated without the confusion of multipath interference typical of real ocean channels. Unmodulated and noise modulated 1-Mc/sec acoustic signals are directed at the surface and the reflected signals are recorded. The magnitude of the randomly varying surface is also recorded. These signals are then sampled, digitized, and recorded onto IBM magnetic tape and analyzed on an IBM-1620 computer. Autocorrelation, probability density, and spectral-density functions are calculated for the surface and the amplitude of the received signal. Crosscorrelation and cross-spectral functions between the noise input and the received signal and between the waveheight profile and the received signal are also calculated. This work is an extension of the work reported in paper D4 by the same authors at the 66th ASA Meeting in November 1963. [Work sponsored jointly by the U. S. Office of Naval Research and the U. S. Navy Underwater Ordnance Station, Newport, R. I.]
Farfield Patterns of a Line Array of Noise Sources
Authors: Lubell A. H.
Published: November 2005

An extended noise source is postulated that consists of n simple sources equispaced along a line. For each simple source, the radiation field will be Fj [t−(r/c)]/r. Fj(t) is assumed to consist of m independent stochastic processes. Each of the m processes may be considered a replica function since it may appear in Fj(t) for any of the n simple sources. To obtain the spectrum for the total field requires that the behavior of sums of replica functions of arbitrary amplitude and time delay be known. Expressing the spectrum as the Fourier transform of the autocorrelation function of the sum of replicas reveals that stochastic processes that are replicas possess interference patterns in much the same way as Fourier-transformable processes. Since each source may contain m independent replica functions, the field of the hypothesized extended noise source will be characterized by m interference patterns. Measurements of the rms field will yield a pattern that is the rms sum of the m-fold replica patterns.
Development of a Mach Wave Radiated by a Point Quadrupole
Authors: Williams J. E. Ffowcs
Published: November 2005

The Mach wave observed near regions of supersonic turbulent flow will eventually develop into spherical waves. Such waves are evident in currently available shadowgraph pictures of the flow near high-velocity model jets. The work described is aimed at understanding the development of these waves from their quadrupole origin and, for simplicity, the theory is worked out for a single point quadrupole. No effect of finite amplitude is considered. The simple theory seems to imply that the observed spherical waves are indeed the Mach waves at a later stage of development and this development is described. [Research supported by the National Aeronautics and Space Administration.]
Panel Excitation by High-Speed Boundary-Layer Turbulence
Authors: Lyon Richard H.
Published: November 2005

The mechanical power that a structural panel receives from a turbulent boundary layer passing over its surface depends in a complicated fashion on the descriptive parameters of both the turbulent flow and the panel. Estimates are made for this power for boundary layers at speeds greater than and less than the bending-wave speed in the panel. The dependence of the power on turbulence parameters is shown to be quite different in the two cases. In particular, low-speed excitation is quite analogous to the “rain on the roof” excitation described by Liepmann. High-speed excitation can be described by Mach-wave generation by a “frozen” pattern of convected turbulence. [Work supported by the National Aeronautics and Space Administration.]
Application of the Crosscorrelation Technique to Wall-Pressure Fluctuations below Free Shear Layers and Oscillating Shocks
Authors: Krause Fritz R.
Published: November 2005

Recent flight and wind-tunnel tests indicate that the skin of large launch vehicles might suffer a high-frequency vibration caused by flow separation and oscillating shocks. It is proposed to classify the noise sources by a crosscorrelation of the wall-pressure fluctuations. For design purposes, the correlation distances of narrow-band pressure components would be mapped. If the transverse flexural wave of a present or future skin panel matches the measured correlation distances, a dangerous skin vibration is probable. A “quick look” is described that will reduce the enormous amount of necessary data to an acceptable minimum. An analysis of systematic and statistical errors is given showing that the power spectrum of the exciting force could be predicted within acceptable confidence by the crosscorrelation technique.
Response of Control Surface Types of Structure to Jet Noise
Authors: Clarkson B. L.
Published: November 2005

As a result of operational experience of failures in ribs of some horizontal stabilizers and skins on a control surface, a theoretical and experimental investigation of the response of these types of structures to jet noise has been initiated. This paper gives the results of an analysis of the free-vibration characteristics of such structures based on some simplifying assumptions. The results are then related to the measurements of the response of some full-scale structures of this type to jet noise.
Excitation of Finite Cylindrical Shells by Boundary-Layer Pressure Fluctuations
Authors: Cottis M. G. , Jasonides J. G.
Published: November 2005

The excitation of a finite, circular cylindrical shell due to subsonic boundary layer pressure fluctuations is investigated with the use of the Green's function method. The pressure-field space-time correlation is assumed in the form of the product of a 0th-order Bessel function and an exponential. The response space-time correlation is calculated exactly by reducing its integral representation to a single integration over the unit circle in the complex plane. Examination of the analytic properties of the integrand, as a function of the pressure-field parameters, reveals all the physically interesting features of the problem; thus, 8 “coincidence” and 4 resonance conditions are uncovered. In addition, this procedure gives rise to a scheme for the classification of the contributing modes in terms of the contributing singularities; in effect, a “representation” for the response evolves.
Effects of Selective Narrow-Band Filtering on the Perception by Normal Listeners of Harvard PB-50 Word Lists
Authors: Castle William E.
Published: November 2005

Productions by one adult male speaker of randomized versions of Harvard PB-50 word lists 1 through 12 were stored on tape. Three listening groups, with five listeners each, were asked to respond to the word lists as each list was subjected to a different condition of narrow-band filtering. Groups 1, 2, and 3 always listened under conditions in which the filters had a geometric center frequency of 1080, 1560, and 1920 cps, respectively. The conditions for a particular group were altered from word list to word list by expanding the band limits and/or by using 1, 2, 3, or 4 filters in series. Word-intelligibility scores, expressed as percentages, were found to be demonstrably high for the narrowest frequency bandwidths used. With a single filter, which attenuated signals at the rate of 30 dB or more per octave, scores of 97%–99% were obtained with bandwidths of 240 cps centered at 1560 and 1920 cps and of 480 cps centered at 1080 cps. Regardless of center frequencies, bands as small as from 1200 to 1440 cps wide consistently yielded word-intelligibility scores from 83%–95%, whether 2, 3, or 4 filters were cascaded.
Visual Control of Phonemic Contrasts: A Test of the Motor Theory of Speech Perception
Authors: Cross D. V. , Lane H. L. , Sheppard W. C.
Published: November 2005

The motor theory of speech perception maintains “articulatory movements and their sensory effects mediate between the acoustic stimulus and the event we call perception.” The inference of mediating articulation is based on certain properties of identification and discrimination at the boundary between identification classes. In the present experiment, these two functions are obtained for a nonlinguistic visual continuum and it is found that they possess the same properties. The plausibility of mediating articulation as an explanatory mechanism for these and other findings is examined.
Basic Information-Bearing Machine-Acoustic Noniterative Segments of Continuous Speech Waves
Authors: Bhimani B. V.
Published: November 2005

Segments that are suitable for use by an electronic recognizer of continuous speech must be defined on the basis of realities of speech events, not on the basis of traditional linguistic division into phonemes, or orthographic divisions of messages into words. A study of modifications of speech sounds by adjoining ones, as approached from a historic and linguistic point of view and organized into a set of rules of cuphonic combination, and also a study of coarticulation, has resulted in a tentative definition of basic information-bearing machine-acoustic noniterative segments of speech. The suitability of these segments for use by an electronic recognizer of speech was tested by applying strict rules for dividing into segments the spectrograms and time-amplitude plots of continuous speech, as well as data in Potter, Kopp, and Green's “Visible Speech” and that in “Acoustico-Cineradiographic Analysis Considerations” by H. M. Truby. [Work sponsored by U. S. Air Force Cambridge Research Laboratories, Office of Aerospace Research, under contract number AF19(628)2766.]
Objective Measurement of Eustachian-Tube Function
Authors: Naunton R. F. , Elpern B. S. , Perlman H. B.
Published: November 2005

Experiments are reported in which sound-pressure changes are monitored in the external auditory meatus during natural deglutition while a 200-Hz. tone is introduced at one nostril. Graphic recordings of these changes characteristically reveal a pressure plateau with a pressure elevation of shorter duration superimposed upon it. The results of a variety of accessory tests have led us to the tentative conclusion that the pressure plateau and the superimposed pressure change are acoustic manifestations of velum elevation and eustachian-tube opening, respectively, occurring in natural swallowing. The experimental technique seems promising as a physiologic method of examining eustachian-tube function under normal and pathological conditions. [Work supported by funds provided under contract NB-02806-04 with the National Institute of Neurological Diseases and Blindness, National Institutes of Health Public Health Service, U. S. Department of Health, Education, and Welfare, and by the Douglas Smith Foundation.]
Heartprints and Other Body Sounds
Authors: Kersta L. G. , Schwartz M. L.
Published: November 2005

Analytical techniques used in voiceprint identification have been shown to give promise in the diagnosis of cardiovascular and other body sounds. This paper reports initial experimental observations in the diagnosis of aortic and pulmonic stenosis. Other potential uses are in the (1) determination of type and results of cleft-palate repair, (2) classification of voice changes occurring during asthmatic attacks, (3) estimation of the type and extent of eustachian-tube disease, (4) early detection of exacerbation of certain psychiatric (schizophrinic) states. The quantized spectral-pattern matching techniques used lend themselves to automated diagnosis as well as to teaching.
Comparison of Susceptibility Tests
Authors: Ward W. Dixon
Published: November 2005

Research is underway to determine how many indices must be used if one is to talk meaningfully about “susceptibility” to auditory fatigue and, presumably, to permanent hearing loss from noise. Toward this end, two groups of college students with normal hearing (25 male and 25 female) are being given a large variety of “susceptibility tests.” This paper is concerned with the intercorrelations among the first three tests administered, tests that differed only in the frequency of the exposure noise: 700–1400, 1400–2800, and 2800–5600 cps. The negligible correlations obtained (a maximum of 0.3) are in accord with Greisen's 1951 findings, and indicate that susceptibility is multifaceted, not simple.
Speech-Discrimination Relations in Normal and Pathological Ears
Authors: Schultz M. C. , Berman Marilyn
Published: November 2005

The routine manner of introducing new speech-discrimination materials is by presentation of the rationale for the test and the particulars of its construction. This information is typically accompanied by data (articulation functions) resulting from listening studies, these latter either varying the presentation levels of the stimuli around normal threshold or changing signal-to-noise ratios at some suprathreshold level(s). Where tests are designed for clinical use, it is assumed that results from normal ears can be related, in some simple manner, to the results that will be obtained in the clinical situation. The present study was designed to evaluate the possible dangers in extrapolating from normative to clinical results. The study employed W-22 stimuli presented to normals under conditions of varying S/N, as well as the same stimuli presented to a hearing-impaired population. The comparisons discussed are those between phonemic confusion matrices generated from incorrect responses of each population.
Experiments in Tactile Speech Perception
Authors: Lucas Robert L.
Published: November 2005

Periodic and transient pulses of pressure, correlated with specific speech sounds, were applied to the palm of the hand by a special transducer. The intuitive responses of subjects indicated the stimuli as “feeling like” certain vowels, stops, and fricatives, and the electrical analog of this taction parallelled the electrical analog of a model of the ear into which the spoken stimuli were fed. The ease of communication when using this synthetically produced “tactile speech” contributes strongly to a theory that tactile-auditory coupling in the central nervous system may exist. Specific waveform details and test results are described. [Work sponsored by the Aeronautical Systems Division, Air Force Systems Command, U. S. Air Force.]
Predicting Vibratory Response of Circuit Boards Located inside an Electronic Package due to a Reverberant Acoustic Field by Energy Methods
Authors: Putukian John H.
Published: November 2005

Using energy concepts, general expressions are derived that predict the vibratory response of a circuit board located inside an electronic package due to a reverberant acoustic field. The usefulness of these expressions is demonstrated in the preliminary design of electronic packages exposed to an intense acoustic field, as exemplified by the acoustic-power output of present air/space vehicles, where cost of laboratory testing to the environmental acoustic levels becomes prohibitive and an approximate vibratory level to be obtained by a theoretical technique becomes valuable. The theoretical analysis, which also shows the effect of the various statistical parameters, was performed on a digital computer. The predicted response is compared with values obtained from an acoustic test. An airtight aluminum electronic package, loaded with circuit boards, of known physical dimensions and material properties, was suspended inside a reverberant acoustic chamber and subjected to a known acoustic-energy input and the resulting vibratory responses monitored. The agreement between theory and experiments is shown to be satisfactory.
Method for the Analysis of Free Vibration of Rotationally Symmetric Shells
Authors: Kalnins A.
Published: November 2005

This paper is concerned with a theoretical investigation of free vibration of arbitrary shells of revolution by means of the classical bending theory of shells. A method is developed that is applicable to rotationally symmetric shells with meridional variations (including discontinuities) in Young's modulus, Poisson's ratio, radii of curvature, and thickness. By means of the method of this paper, the natural frequencies and the corresponding mode shapes of axisymmetric or nonsymmetric free vibration of rotationally symmetric shells can be obtained without a limitation on the length of the meridian of the shell. To illustrate the application of the method given in this paper to particular shells, some results of free vibration of spherical and conical shells obtained earlier by means of the bending theory are reproduced by the general method of this paper, and a detailed comparison is made. In addition, paraboloidal shells and a sphere-cone shell combination are considered, which have been previously analyzed by means of the inextensional theory of shells, and natural frequencies and mode shapes predicted by the bending theory are given. [Research has been supported by a grant from the National Science Foundation.]
Theoretical and Experimental Comparison of the Modes of Vibration for a Stiffened Pressurized Cylinder
Authors: Plumblee Harry E. , Rudder Fred F.
Published: November 2005

This paper describes an extension of the vibration theory of stiffened cylinders to include effects of internal pressurization on normal modes. The analysis is primarily based on the Rayleigh energy method and utilizes Lagranges equation for obtaining equations of motion and normal modes. A 1/7 scale model of a C-141 fuselage section was freely suspended and exposed to acoustical excitation. Mode shapes and frequencies were measured with miniature accelerometers. Results include a comparison of theoretical and experimental mode shapes and frequencies.
Free Vibrations of Viscoelastic Spheres
Authors: Coquin G. A.
Published: November 2005

The frequency equations for an isotropic, viscoelastic sphere with a tractionfree surface may be obtained directly from the corresponding equations for an elastic sphere by replacing the elastic constants with complex, frequency-dependent moduli characteristic of the material. In this paper, an approximate method is used to obtain roots of the viscoelastic-frequency equations for low-loss materials. Once the frequencies of vibration are known, the Q's of the various torsional and spheroidal modes can be calculated easily. Numerical results are given that enable the complex moduli of a material to be determined from measurements of the frequency of vibration and decay constant of the modes of a sphere.
Machine-Aided Formant Determination for Speech Synthesis
Authors: Strong William J.
Published: November 2005

A digital computer is used to analyze and synthesize digitized speech. Speech samples of 2 sec duration are processed by 100 contiguous bandpass filters that cover the range from 20 to 3980 cps. Each filter output is full-wave-rectified, low-pass-is cosine transformed; the high-order coefficients are used to determine the fundamental frequency; the low-order coefficients are used to determine a “wide-band section.” The wide-band sections are displayed in time sequence on a CRT and an operator specifies 4 poles by means of voltage-knob inputs to the computer; the frequencies and amplitudes of the poles are stored; the program then moves to the next section. The parameters thus determined are used to control a 4-pole parallel synthesizer. Work is in progress on vowels, glides, nasals, and voiced stops. The selection of 4 poles in a section is often ambiguous; a look-ahead feature that displays future sections in the time sequence may help to remove the ambiguities.
Launch-Vehicle In-Flight Acoustic-Environment Predictions
Authors: George B. W.
Published: November 2005

A state-of-the-art prediction of the in-flight external acoustic environment of a current launch vehicle was made for NASA-Marshall Space Flight Center. Representative predicted environment parameters are presented in the form of sound-pressure-level time histories and 13-oct-band spectra for each major stage or module on the vehicle. Methods used in the prediction are based on (a) wind-tunnel acoustic data on scaled models; and (b) normalized empirical curves available in the literature. Aerodynamic-noise sources on the vehicle and local areas with severe environments (e.g., near proturberances) are discussed. Highest noise environment over the launch flight period occurs on the nose cone. The predictions are compared with subsequent flight measurements and the results interpreted. The validity of scaling from model to flight data is demonstrated. Oscillating-shock-wave effects are found to contribute significantly to the acoustic signals recorded in flight in the transonic speed range. Comparisons are included of these data with recent published data on other types of flight vehicles.
Conversion of Lighthill's Equation on Jet-Noise Generation to an Impedance Concept
Authors: Vatz Irvin P.
Published: November 2005

M. J. Lighthill derived an equation of proportionality for the generation of sound by subsonic turbulent jets. This question is modified to an impedance form by extracting thrust, impedance, and nondimensional parameters. The equation is dependent upon information that is generally available to engineers for any particular jet engine. The equation also is modified empirically for use with supersonic jets. Some dimensionless jet-noise spectra are extrapolated into a frequency-dependent equation that is substituted into the modified Lighthill's equation. The result is a prediction method for the acoustic power spectrum at its source.
Response Patterns of Populations of Units along Auditory Pathway to Pure Tones and Bands of Noise
Authors: Starr A.
Published: November 2005

Activity of groups of units was recorded in awake unrestrained cats with chronically implanted semimicroelectrodes. Pure tones [2 40 kHz, 50–90 dB SPL (sound-pressure level), 2–4 sec in duration] were presented binaurally through miniature speakers mounted on the head. These stimuli caused a decrease of unit activity at superior olive, inferior colliculus, medial geniculate, and auditory cortex; an increase of activity occurred only at onset and offset of tones. In contrast, cochlear nucleus had a sustained increase of activity with particular tones while stimuli just above those frequencies evoked a decrease in activity. When bands of noise were presented, response patterns differed. Narrow bands of noise (35 Hz wide) evoked responses in auditory pathway sites central to cochlear nucleus resembling pure-tone responses. Slightly wider bands of noise (75 Hz) did not effect any over-all change in activity whereas still wider bands (150 Hz and above) evoked an increase in unit activity. Thus, response patterns of populations of units can vary from net inhibition to net excitation as a function of the bandwidth of the acoustic stimulus.
Temporal Summation in the Superior Olivary Complex of the Cat
Authors: Boudreau James C. , Tsuchitani Chiyeko
Published: November 2005

Tones of varying duration were delivered to anesthetized cats. Single-unit recordings revealed that some cells exhibited latencies up to 80 msec to long-duration threshold tones. Progressive shifts in latency were seen with increases in intensity. These units exhibited no spontaneous activity and were excited by ipsilateral stimulation only. Increasing the duration of the tone to about 80 msec resulted in lowered thresholds of response. Stimulation by two successive subthreshold tones resulted in increased probability of response to the second tone when the two tones were separated by a silent period as long as 60 msec. [Work supported in part by National Institutes of Health, U. S. Department of Health, Education, and Welfare.]
Representation of the Two Ears by Single Units in Primary Auditory Cortex of Unanesthetized Cat
Authors: Hall J. L. , Goldstein M. H.
Published: November 2005

Tone bursts, noise bursts, and clicks were presented at a moderate intensity to the right ear, to the left ear, and simultaneously to both ears of cats immobilized with gallamine triethiodide [J. Acoust. Soc. Am. 39, 1226(A) (1966)]. For about 80 well-isolated cells in 12 cats, of those cells that responded to tone bursts about 29% were influenced only by a stimulus to the right (contralateral) ear, 3% only by a stimulus to the left (ipsilateral) ear, and 68% by stimuli to either ear. About 68% gave a greater response to stimulation of the right ear, 10% to stimulation of the left ear, and 22% were nearly symmetrical. (Response refers to a change in unit activity attributable to the acoustic stimulus.) Results for noise bursts and clicks were similar. Several forms of binaural interaction were observed. [Work supported in part by the Public Health Service, U. S. Department of Health, Education, and Welfare, and by the U. S. Air Force Office of Scientific Research.]
Crosscorrelation of Dispersive Waves
Authors: White Pritchard H.
Published: November 2005

The use of crosscorrelation as a tool for analyzing motion in complex systems leads to the necessity of understanding crosscorrelation of dispersive waves. Starting from basic principles, the crosscorrelation of any form of dispersive wave has been derived. Special cases that have been considered are water waves and flexural waves in a thin beam. Exact and approximate formulations for the crosscorrelation of waves of frequency-bandlimited noise have been considered. Experiments with flexural waves in single- and multiple-path systems have provided excellent verification of theoretical predictions.
Mechanical-Impedance Concepts Applied to the Dynamic Flexural Response of Beams
Authors: Wieland H. E. , Hixson E. L.
Published: November 2005

A detailed experimental analysis of the flexural response of free-free beams by mechanical-impedance methods is presented. Emphasis is placed on the resonant and antiresonant frequency shifts due to shear flexibility and rotary-inertia effects. Experimental tests were carried out on beams of two materials (aluminum and acrylic) having L/D ratios from 10 to 40. Results indicate resonant and antiresonant frequency shifts due to shear flexibility and rotary inertia as high as 34% for low L/D ratios and higher modes of vibration. Material-damping factors were determined from impedance values at resonant and antiresonant frequencies. Theoretical predictions of driving-point impedance at the center and motion transmissibility to the ends were made by J. C. Snowdon [“Mechanical Impedance of Free-Free Beams,” J. Acoust. Soc. Am. 37, 240–249 (1965); “Transverse Vibration of Beams with Internal Damping, Rotary Inertia, and Shear,” ibid. 35. 1997–2006 (1963)]. Resonant and antiresonant frequencies were predicted to an average of 0.8% for aluminum and 2.5% for acrylic. Damping factors of 0.00152 for aluminum and 0.0515 for acrylic were indicated. The results for this simple structure add validity to the application of experimental impedance methods in the study of complex structures for which theoretical analysis is impractical.
Analytical Investigation on the Vibrations of Clamped Plates of Complicated Shape
Authors: Passarelli Ralph
Published: November 2005

The problem of free transverse vibrations of plates of rectangular, circular, and elliptical shape is discussed in standard textbooks. In the case of plates of more complicated shape, it would be necessary to find first the natural system of coordinates. Even with the natural coordinate system known, it is very probable that the method of separation of variables would not be applicable for the solution of the partial differential equation. It is shown in this study that it may be advantageous to conformally transform the given shape onto a unit circle. Several numerical techniques are available for the determination of the mapping function. The boundary conditions become, for a clamped plate, u(r,θ,t)|r=1=0, (∂u/∂r) (r,θt)|r=1=0. A closed-form solution of the transformed differential equation seems unlikely. Galerkin's method is used for the determination of the fundamental frequency. The method is illustrated in the case of a clamped circular plate with two flat sides. [Research sponsored by the U. S. Office of Naval Research.]
Resistive Electrical Networks for the Study of Shell Vibrations
Authors: Shinaishin O. A.
Published: November 2005

This study investigates the free and forced vibrations of a thin elastic cylindrical shell, both as a split tube and as a complete cylinder of finite length, by means of an analog network of pure resistances. Assuming all boundaries to be simply supported, and from Donnell's simplified equation for a cylindrical shell, two simultaneous fourth-order partial differential equations were used to describe the dynamic behavior. By the finite-difference method, those equations were transformed into a number of algebraic equations that were solved by the resistive analog described, in its initial form, by G. Liebmann, to give the natural frequencies and mode shapes. The results were compared with values obtained on a digital computer from the analytical solution. Good agreement existed for the lower modes only, while larger differences occurred at the higher modes. The results could be improved greatly by using a larger network. The simplicity of the method and the flexibility of the boundary conditions make it useful for preliminary calculations of the natural frequencies and response of such structures to harmonic and random excitations.