bluuebunny/crossref_metadata_2025 huggingface dataset:
Sound Shadow Cast by Head and Ears
Authors: Harris J. D.
Published: November 2005

A dummy head was constructed of a balsa-wood mannekin with 38-in. coating of rubber simulating the impedance of human flesh, incorporating two W.E. 640AA mikes at the position of the eardrums, and with removable pinnae. The pinnae of actual persons was molded by a plaster of paris transfer technique and placed on the head one pair at a time. Intensity variations from 500–15 0000 cps at one eardrum wer recorded at a selection of azimuths and elevations in 30° steps; and at a selection of frequencies and azimuths the head was rotated with continuous recording of differential mike output. Thus, the study somewhat extended the important work of Jahn and Vogelsang and of Nordlund. The head itself throws the more significant shadow, but intereardrum differences are not smooth over azimuth, elevation, or frequency, so that each person must learn the acoustical properties of his own physiognomy. The pinnae certainly throw secondary shadows, but their effect is more often than not to reduce the large intereardrum intensity differences (commonly more than 10 dB) and to render them more meaningful (an intereardrum difference of 10 dB is more than sufficient to lateralize a sound completely.) [Research generously supported by the U. S. Vocational Rehabilitation Administration and The Seeing Eye, Inc.]
Some Preliminary Studies of Hearing Loss with an Arc-Discharged Impulse Noise Generator
Authors: Loeb M. , Fletcher J. L. , Benson R.
Published: November 2005

Twelve subjects were exposed on different days to 200, 300, or 400 impulses produced by an arc-impulse noise generator and presented once every 2 sec, once per second twice per second, or 4 times per second. The intensity of each impulse was approximately 156 dB, with positive and negative peaks each having a duration of approximately 40μ sec. It was found that appreciable TTS was produced only for frequencies above 4000 cps and that pulse rate did not significantly influence TTS. In a subsequent experiment, it was found that if a 100-dB train of clicks, 0.2 sec in duration, was presented before each impulse, TTS was not reduced. This finding implied that either the acoustic reflex was ineffective against the energy producing the high-frequency TTS or that the reflex was insufficiently activated. In a third study in which impulses were presented 10 times per second, TTS was appreciably less than that produced by impulses presented once per second, so it cannot be said that the acoustic reflex is not a factor for impulses with these characteristics. A brief description of the apparatus is included in the paper.
Axial Vibrations of a Semiinfinite Viscoelastic Rod with External Elastic Constraint
Authors: Flügge W. , Hutchinson J. R.
Published: November 2005

The response is considered of a semiinfinite viscoelastic rod, with uniform external elastic constraint along its length, to an enforced sinusoidal displacement of its end. Above a certain critical frequency, the steady-state solution consists of damped traveling waves moving away from the forced end. For lower frequencies, however, the waves travel out of the rod toward the forced end. A brief explanation of this interesting phenomenon is given by studying the work done on the rod. The transient analysis is performed, for the rod initially at rest, by applying a Fourier sine transform to the space variable. The resulting integral solution is integrated numerically for a purely viscous rod being forced at a frequency below the critical frequency. This solution shows how the disturbance is initially propagated away from the forced end and subsequently settles down to the steady-state solution of the wave traveling toward the forced end.
Part I. Musical Relations and the Ear
Authors: Benade Arthur H. , Kent Earle L.
Published: November 2005

This session deals with fundamentals of sound waves, resonance, pitch, loudness, timbre, musical intervals, and musical scales. Special demonstration apparatus, motion pictures, slides, and tape recordings are used. It is geared primarily to the music and science students.
Part II. Musical Sources
Authors: Hutchins Carleen , Hall Jody C.
Published: November 2005

This portion deals with the fundamentals of a number of instruments. The effect of temperature upon tuning, the importance of materials and bore calibration upon response, tone quality, and intonation, the directional characteristics of some instruments, and the like are demonstrated. Special emphasis is given to the pioneering work being done by Mrs. Hutchins on the violin family. Several new instruments of her design and construction are demonstrated.
Scanning Electron Microscopy of the Cochlea
Authors: Jako G. J. , Goodman J. , Strong M. S.
Published: November 2005

A recent development, scanning electron microscopy, makes possible, with its high magnification (×100 to ×100 000) and great depth of focus (300 times greater than optical microscopes), three-dimensional investigation of the structure of the cochlea. In our preliminary study, fresh guinea pig cochleae were fixed by several different methods. The fixed cochleae were frozen and surface specimens of the organ of Corti were prepared by “planing” with a microtome. [G. J. Jako, Frozen Sectioning Technique for Studying Distribution of Dyes and Isotopes in Guinea Pig Cochleae, abstract, Intl. Congr. Biophys., 1st (1961)]. The specimens were then dehydrated and coated with a thin, 500-Å thick, gold film in a vacuum evaporator. The details of specimen preparation and the interpretation of the results will be discussed.
A Tribute to S. S. Stevens
Authors: Rosenblith Walter A.
Published: November 2005

On January 18, 1973, S. Smith Stevens, Professor of Psychophysics at Harvard University, died at the age of 66. A last-minute change was made in the program of the 85th Meeting of the Acoustical Society of America to include a session in Stevens's honor. The texts of the four papers outlining Stevens's contributions to science as researcher, philosopher, and educator are published here. The April 1973 issue of this journal contains an obituary by Hallowell Davis that tells more about Stevens's life.

Provost Walter A. Rosenblith of the Massachuseits Institute of Technology served as Chairman of the session. His opening and closing remarks are presented in the following paragraphs.
Stevens as educator
Authors: Hirsh Ira J.
Published: November 2005

This paper reviews the significance of Stanley Smith Stevens's role as a teacher.
S. S. Stevens: his impact on physiology
Authors: Davis Hallowell
Published: November 2005

This paper discussed the contribution of S. S. Stevens to the field of physiology.
Stevens's operationism
Authors: Newman Edwin D.
Published: November 2005

Stevens pushed Bridgman's operational definition beyond the observed to include the observer.
Noise reduction programs for DC-8 and DC-9 airplanes
Authors: Frasca R. L.
Published: November 2005

An in-depth review of the results is presented of current and recently completed Government and Douglas Aircraft Company sponsored noise-reduction programs for DC-8 and DC-9 airplanes. The relationship of these programs to other efforts by Douglas to develop quieter CTOL airplanes is briefly outlined. The engine/nacelle concepts studied were (1) application of nacelle acoustic treatment; (2) variable-area exhaust nozzles; (3) jet exhaust noise suppressors; and (4) engines with larger-diameter new front fans. Acoustic analyses leading to the selection of certain engine/nacelle configurations are described, as well as design constraints which limit the noise-reduction capability of certain designs. Acoustic design features of the modified engine/nacelles are discussed, along with estimates of the changes in aircraft community noise levels, as well as estimates of the changes in aircraft weight, performance, cost, and operational restrictions. The noise-reduction estimates for the DC-8 and DC-9 programs are based on ground runup and flyover noise tests. Comments are presented on the potential noise-reduction benefits, and associated aircraft operational problems, resulting from noise-abatement operating procedures. [This work was sponsored by the Federal Aviation Administration, The National Aeronautics and Space Administration, and The Independent Research and Development Program of the Douglas Company.]
Sound Propagation in a Shadow Zone
Authors: Polly Robert C.
Published: November 2005

In this paper, the behavior of the sound field within a shadow zone is briefly examined. Under certain atmospheric conditions, ray acoustics can be used to derive a suitable relationship for the intensity of an “effective shadow zone.” The solution obtained by the methods of ray acoustics is compared with the normal-mode solution of the wave equation, and the basic limitations of both approaches are pointed out. Acoustic measurements recorded during numerous engine tests have indicated that there are two major factors that affect the behavior of the sound field within the shadow zone. These are (1) the magnitude of the surficial velocity gradient, and (2) the surface wind conditions. These two factors have been incorporated into an empirically derived expression for the shadow zone attenuation rate. Using this relationship, it was found that about 90% of the calculated values were within ±5 dB of the measured values.
Measured Variation of Acoustic Parameters with Altitude
Authors: Tedrick Richard N. , Alexander James R.
Published: November 2005

Measurements of the internal and external sound-pressure levels are reported from the flight of a Saturn IB space vehicle. These measurements show the differences in sound generation and transmission that occur as the vehicle rises from the launch site near sea level to several hundreds of thousands of feet. These changes are related to the variation in atmospheric and flight parameters (notably density and velocity) with altitude.
Computer Simulations of Highway Traffic and Associated Noise Levels
Authors: Fletcher C. M. , Clark W. E.
Published: November 2005

A set of computer programs has been developed that provides the capability to simulate highway traffic and to calculate the associated noise levels. Extensive measurements of vehicular noise have been classified and averaged to produce characteristic spectra for passenger cars, heavy trucks, motorcycles, and other classes of vehicles. These spectra are used to represent the contribution of individual sources along a roadway. Sources are arrayed across multiple lanes to satisfy a stated proportion of cars, trucks, and other types of vehicles, as well as specified vehicle flow and speed. The individual contributions are adjusted for the effects of source—observer distance, air attenuation, vehicle speed, etc., and summed to produce a sample spectrum. Sets of these sample spectra can then be processed by computer to yield dBA values and statistical summaries of these values, or they can be utilized in the same fashion as measured data to determine noise levels adjacent to a highway. [Work performed as a part of Highway Research Board Project NCHRP 3–7.]
Evaluation of Acoustical Enclosures, Using Markov Chains
Authors: Peterson Roger H.
Published: November 2005

Cover systems used on machinery can be an important contributor to noise reduction. The design and evaluation of cover systems is largely experimental, as exact theoretical evaluation is generally considered impossible. Architectural acousticians have made use of statistical procedures that ignore acoustical-wave characteristics to determine approximate reverberation and sound levels. These procedures can be extended to approximately describe the problem of enclosures. A severe limitation is that cover geometry is not considered. Markov-chain procedures were used to describe geometric cover effects. An absorbing Markov chain was formulated to describe statistically the passage of an acoustical energy “bundle” from machine source, through a three-dimensional cover system, to external locations. The source directivity, and cover absorption, and transmission-loss coefficients are required input in addition to cover geometry. A procedure was devised and programmed for an IBM-7094 to manipulate mathematically the Markov chain to determine a statistical approximation of cover attenuation to these external locations. Experimental investigation of model cover systems was used to varify and improve the procedure.
Unit Responses from the Auditory Nerve of Anesthesized Guinea Pigs
Authors: Berry Nancy C. , Mundie J. Ryland
Published: November 2005

37 primary auditory neurons were isolated by means of a new x-ray stereotaxic technique. Intricate changes in intensity and small shifts in frequency response have been thoroughly investigated with varying repetition rates. Latest endeavors are to analyze the responses obtained with human voice patterns used as the stimuli. All experiments were run on line with a digital computer, which is used for data collection, storage, and management, as well as for analysis of the data by various techniques. Measurement of average interval, average pulse position, and pulse-interval distribution have been made on all data.
Afterdischarge Following Tone-Burst Stimuli in Single Units of the Dorsal Cochlear Nucleus of the Chinchilla
Authors: Mast Truman E.
Published: November 2005

Single-unit activity in the dorsal cochlear nucleus of the anesthetized chinchilla was studied by using steel microelectrodes. The stimuli were gated 125-msec tone bursts with rise and fall times of 5 msec. 16 of the 60 units studied showed some form of “afterdischarge.” The duration of the afterdischarge was variable, but was often as long as 100 msec. The duration generally increased with increasing stimulus intensity. These units, with one exception, have responded during stimulation as well as after it. Neuronal firing during the afterdischarge was generally at a lower rate than during the initial response. There may or may not be a brief silent period after the end of the stimulus and before the afterdischarge. The after discharges are seen over a wide range of tonal frequencies, including the best frequency for a particular unit. Units with these characteristics have shown no definite pattern of anatomical distribution in the dorsal cochlear nucleus. [Work supported by National Institutes of Health, Public Health Service, U. S. Department of Health, Education, and Welfare.]
Mechanical and Acoustic Mobility of a Complex Aerospace Structure Utilizing Digital Data-Reduction Techniques
Authors: Bozich Daniel J. , Sutherland Louis C.
Published: November 2005

A complex aerospace structure was used to obtain experimental measurements of input and transfer impedances. The combined theoretical and experimental investigation resulted in several significant advances in the technique of impedance measurements. The utilization of an on-line analog/digital computer system for data acquisition and data analysis is considered to be the major achievement of the over-all program. Other results included the ability to relate successfully acceleration-response data obtained from a variety of sinusoidal and bandwidth-limited random-noise mechanical- and acoustic-excitation sources. This paper covers the developments leading up to the use of the analog/digital data system, the experimental procedures and results, and a discussion of the results. [Work supported by NASA-MSFC-P and VE.]
Asymptotic Theory for the Vibrations of Elastic Plates
Authors: Widera O. E.
Published: November 2005

Differential equations governing the vibrations of plates are established in a systematic and consistent manner without making any of the usual a priori assumptions regarding the distribution of stresses and displacements over the thickness of the plate. The analysis consists of the application of the boundary-layer technique to the equations of the three-dimensional theory of orthotropic elasticity. After suitably nondimensionalizing these equations, an asymptotic expansion of both the stress and displacement variables and length scales in terms of a small plate parameter is performed. By equating corresponding powers of the parameter, successive systems of differential equations are obtained. The lowest-order system in each case yields the different classical thin-plate equations. The higher-order systems yield the corresponding higher-order terms in the expansions and constitute thickness corrections associated with the effects of transverse shear, normal stress, and rotatory inertia.
End Vibrational Modes in a Cylindrical Shell
Authors: Frymoyer E. M.
Published: November 2005

The range and character of the end vibration of a finite bar, plate, or shell are determined by the behavior of the complex and imaginary branches of the frequency spectrum for the infinite case and the boundary conditions. Depending upon the geometry and frequency, the decaying end modes may have a propagating or nonpropagating character. In certain frequency ranges, the end mode may be the predominant contribution to the total displacement field. Dispersion curves are presented for the complex modes for several circumferential orders of the cylindrical-shell vibration. The end-displacement field is investigated under various boundary conditions. Comparison is made with the case of bars and plates so that the results may be generalized to more-complex vibrators.
Axisymmetric Vibrations of a Solid Elastic Cylinder Encased in a Rigid Container
Authors: Hutchinson James R.
Published: November 2005

The purpose of this study is to investigate the effects of end boundary conditions on the vibrational characteristics of solid-propellant rocket motors. Previously, in the literature, solutions have been obtained based on those of an infinitely long cylinder. These solutions yield only certain sets of possible end boundary conditions for a finite cylinder, but not those considered (i.e., fixed on all boundaries). The approach consists of choosing a series of functions with unknown coefficients. Each term satisfies the governing differential equation and the boundary conditions on the axial displacement. The boundary conditions on the radial displacement are approximated by an orthogonalization procedure. This method yields an eigenvalue matrix whose coefficients are transcendental functions of the frequency. The accuracy of the final solution depends on how well the radial-displacement boundary conditions are satisfied. It is found that the procedure converges, and that sufficient accuracy is achieved, through the use of 20 terms in the series. The limitations of the simpler method, based on an infinite cylinder, are discussed by comparing results obtained from both methods.
Digital Generation of a Linear FM Pulse of Given Time-Bandwidth Product
Authors: Vettori G.
Published: November 2005

A method is described for generating a precisely phase-controlled linear FM pulse of large time-bandwidth product T⋅W=N by digitally phase-modulating a square-wave carrier at frequency fo with phase jumps of magnitude π/m, where design parameters N and m are powers of 2. A parabolic function generator, which sequentially computes the square of the number of clock input pulses, furnishes modulation orders and is basically comprised of 2s+1 flip-flops (where 2s=m⋅N). Frequency of input pulses is m⋅W, where sweep bandwidth W has to be chosen smaller than 2fo/1+m. Phase quantization noise takes the place of “linearity” and “stability” concepts in analog linear FM generators, and its power can be controlled by design parameter m, with a reduction of 6 dB for each doubling of the value of m. Bandpass-filtering of the output-modulated signal gives, in many cases, a satisfactory signal-to-quantization noise ratio, even with m=2. [The system described was developed by the author and H. W. K. Kelly, now of Admiralty Research Laboratory, Teddington, England.]
Underwater Signal Characteristics of Porpoises and Killer Whale as a Function of Size and Acoustic Properties of the Head
Authors: Heindsmann T. E. , Donaldson J. G. , Lowell F. C.
Published: November 2005

Analyses of the underwater audio and ultrasonic signals of Orca orcinus (killer whale) in groups and as individuals show both similarities and pronounced differences versus the emissions of smaller porpoises. Acoustic signal content and frequency can be shown to be related to body size, age, and species. Comparative data on the acoustical properties of tissues and bone in the head region are presented, including recently obtained laboratory pulse-tube measurements, following anatomical dissection. Their possible function in formation of the different signal types and in directional listening by these largest animals of the dolphin-porpoise group is discussed relative to the published theories for that of the smaller species. Previous (1965) electroacoustic 13-oct-band (16 Hz-63 kHz) and multispeed oscillographic analyses on the killer-whale signals have shown a number of distinct signal types, including modification of pulse repetition rate, fundamental frequency, and signal complexity during a series of emissions. A more acceptable alternate hypothesis to the layman's assumption of animal conversation is that of a continuous-feedback sonar to permit matching signal and returning echo versus background-noise reverberation and target characteristics. Other signals that may serve communication functions of location and homing, identification, and warning are described in terms of their acoustical parameters.
Acoustic-Wave Fluctuations in a Random Medium with Spherical Object Inclusion
Authors: Knollman G. C.
Published: November 2005

An approximate theoretical treatment is given the problem of expected statistical signal fluctuations for scalar-wave propagation in a spatially random, inhomogeneous medium containing a spherical scattering object positioned on the source-receiver line-of-sight. The transmission medium is one of weak refractive-index variation with statistical isotropy; the inhomogeneities are taken large in scale with respect to the wavelength. (Such circumstances can be indicative of conditions in the ocean and the atmosphere.) Spherical-object inclusions of arbitrary wave impedance and arbitrary size (yet large in comparison with the wavelength) are considered. No restriction is placed on the object position, except that it be far from source and receiver relative to the characteristic correlation length associated with the inhomogeneities. Results are compared with those for propagation in a random medium devoid of any regular scattering anomaly. Findings are also presented of a corroborative experimental program being conducted in a controlled, simulated-random underwater environment. [Work supported by the Lockheed Independent Research Program.]
Scattering by Two-Dimensional Array of Identical Rigid Spheres
Authors: Harbold Mary L. , Steinberg Bruce
Published: November 2005

The scattered field from a symmetrical array of rigid spheres positioned in a plane normal to the propagation direction of a plane acoustic wave in air has been extensively studied. Continuous measurements of both amplitude and phase in selected planes provided a complete mapping of the nearfield region for different values of the distance d between sphere centers and λ, the wavelength. Results show that the interaction region, where multiple scattering predominates, is a volume defined by a contour surface that is symmetric about the geometrical center axis of the array. Within the volume, very large but smooth fluctuations in amplitude occur, while outside the volume-independent scattering is observed. Investigations show that the size and boundary of the volume are completely determined by the ratio d/λ for a fixed sphere size. Effects due to the variation of this ratio and angle of incidence have also been investigated. [Work supported by the U. S. Office of Naval Research.]
Numerical Solution for Transient Scattering from a Hard Surface of Arbitrary Shape
Authors: Mitzner Kenneth M.
Published: November 2005

The problem of transient scattering from a hard surface S reduces to the solution of an integral equation for the potential at S. To facilitate numerical solution, S is divided into N zones, on each of which the potential is assumed constant, and time is also discretized. These approximations lead to a set of N algebraic equations relating the present values of the potential to the retarded values and to the incident field. When the zoning is done properly, each equation involves only one present value, and thus the potential can be calculated by a step-by-step numerical process. It is important to compute the coefficients in the N equations accurately; this is accomplished by a numerical technique that takes into account the curvature of the zones and the variation in time retardation across a zone. For scattering from a sphere, results agree very well with the exact solution. [Work supported by the U. S. Office of Naval Research.]
Recent Advances in Pure-Fluid Acoustic Amplification
Authors: Unfried H. H.
Published: November 2005

The rapidly expanding field of pure-fluid amplification (fluerics) has brought forth applications and requirements that are stressing the capabilities of the wall attachment and proportional-type amplifiers. The increasing necessity for greater bandwidth, improved signal-to-noise ratio, and increased dynamic range indicates that recent developments with pure-fluid acoustic amplification will become an important phase of this infant field. Several years ago, predictions were made that bandwidths of 10 kHz would probably never be realized with pure-fluid amplification. Today, 10-kHz bandwidths are possible with carrier techniques, and recent studies with hot gas jets indicate that bandwidths of 50 kHz are within the near realm of possibility. Past research on the characteristics of sound-sensitive jets, jet edgetones, and jet ringtones is now playing a significant rôle in the fluerics field. Sound-sensitive laminar jets have an inherent amplification of perhaps 105, depending on the noise level of the undisturbed flow. The natural signal compression that results from the saturation of the developed vortex flow is detrimental to linear amplitude response, but for certain applications this phenomenon is desired. Perhaps the greatest disadvantage for the application of sound-sensitive jets for acoustic amplification is the restricted operational Reynolds number and the power-handling capability. The lack of knowledge on vortex flows in the vicinity of irregular solid boundaries is one of the most important factors retarding advanced studies.
Dynamic Response of a Cylindrical Shell Subjected to Instantaneous Heating and Impulse
Authors: Lyons W. C.
Published: November 2005

An elastic-plastic theory is used to predict the dynamic response of a cylindrical shell that is subjected to the simultaneous action of instantaneous heating and impulse. A simple strain-hardening law is used to simulate the plastic behavior of the shell material. The change in the material properties of the shell owing to temperature is taken into account. Also the inertia due to the instantaneous heating is considered. The response of the shell is separated into two parts: the maximum deformations obtained and the permanent deformations. For both response modes, maximum deformations, and permanent deformations, plots are given for impulse versus temperature at a given deformation. From these plots, the effect of the change in material properties owing to instantaneous heating can be obtained. It is found that the effect of the change in material properties owing to temperature is far more important than the inertia loads associated with the instantaneous temperature increase. Therefore, in future problems that concern instantaneous heating and impulse, the effect of the inertia owing to the dynamic temperature strain can most likely be neglected when compared to the inertia effects associated with the impulse.
Calculation of Frequency-Modulated Sound Pulses
Authors: Hickling Robert , Thomas D. H.
Published: November 2005

Approximations to the Fresnel integrals that have been developed during the past few years make it possible to calculate the spectra of linear frequency-modulated sound pulses with relative ease. Some examples of the calculated spectra are given and their use, in obtaining FM echoes from hollow aluminum spheres in water, is described.
Determination of “Three-Dimensional” Directivity Patterns of a Transducer from Discrete Response Measurements
Authors: Smith D. A. , Johnstone J. E. , Baker D. D.
Published: November 2005

An experimental program was undertaken to study the measurement and and presentation of “three-dimensional” directivity patterns of an underwater acoustic transducer. The output of a fixed transducer was sampled discretely and recorded on paper tape as a small projector was scanned over a plane aperture in the farfield. This was done to simulate the use of an array of small probes to measure directivity of a shipboard transducer. The spacing between data points was a variable parameter. The data were reduced on a CDC-3200 computer; interpolation techniques were used to generate continuous directivity functions. A useful presentation of the data consisted of contours of equal response plotted on a linear grid of elevation versus azimuth. The contour plots for different spacings are compared; these plots are also compared with equivalent plots generated from a series of conventional directivity patterns. The accuracy of the plots was surprisingly good in the case of relatively widely spaced data—for example, with the spacing equal to about one-third, the half-power beamwidth of the major lobe of the transducer pattern. This would indicate that measurement of relatively few discrete response data and computer processing can provide a useful means of determining transducer directivity.
Computer Processing and Presentation of Discrete Transducer Directivity Data
Authors: Johnstone J. E. , Smith D. A. , Baker D. D.
Published: November 2005

Different interpolation techniques were used to generate a continuous transducer directivity function from a series of response data measured at discrete points over a plane area. The problem of the presentation of such information is discussed. A contour plot was used as a compact way to present all of the data in a form that can be examined rapidly for practical information about the transducer-beamwidth, side-lobe levels, and side-lobe locations. However, examination of such contour plots proved to be an unsatisfactory way to compare them accurately. The technique used for this purpose was to compare corresponding plots of response versus elevation at various azimuths. The most practical format for the contour plots appears to be a linear grid of elevation versus azimuth. A CDC-3200 computer was used to perform all data processing, including generation of the contour plots.
Physical Correlates of Perceived Acoustic Traits
Authors: Voiers William D.
Published: November 2005

Relationships among 23 physical and perceptual voice variables were examined by means of factor analysis and partial correlation techniques. The observed relations between physical voice variables and voice-rating data obtained with unprocessed speech permit tentative identification of the “normal” physical correlates of various perceived voice characteristics. However, results based on voice ratings of degraded speech indicate that, while the physical correlates of some perceived acoustic traits are quite stable over various forms of speech degradation, the physical correlates of others may be drastically altered by degradation of the speech stimulus. [Research reported in this paper sponsored by the U. S. Air Force Cambridge Research Laboratories, Office of Aerospace Research.]
Speaker Verification
Authors: Chapman W. D. , Li Kung-Pu
Published: November 2005

Speaker verification is defined as the process of confirming the purported identity of an informant. An automatic verification system is required to give a YES-NO decision with a corresponding measure of confidence. It would be desirable to begin with a set of ideal measurements that extract only the parameters in the voice relating to speaker identity. Since the significant parameters cannot be completely specified, an adaptive decision procedure has been utilized to focus on the characteristics that differentiate a particular speaker from a set of potential impostors. The adaptive linear-threshold element employed in these experiments is trainable for separating all input patterns into two classes. Such an approach is attractive because the measurement hardware is minimized, and the decision mechanism may be simulated quite readily on a digital computer. The present paper explores the extent to which adaptive linear-threshold elements are able to verify a person's identity based on quantized spectral patterns of his voice.
Voice Classification by Hierarchical Clustering
Authors: Silbiger Herman R.
Published: November 2005

In the speech-quality evaluation of transmission systems, the selection of a sample of speakers is often a problem. This study derives relationships between speakers on the basis of their perceptual similarities and differences. A 20-item semantic differential scale was developed to yield maximum discrimination between speech from different speakers. The ratings on these scales were found to have high reliability over samples from various populations of raters and over time. Ratings were obtained on voices of 24 male and 23 female speakers. The distances between the semantic differential profiles of these speakers were calculated. These distances were then used as the input for a computational method that yields clusters of the profiles. This method, called hierarchical clustering, orders the voices in a treelike structure from a two-voice cluster to a cluster containing the total sample. The obtained branch heights in the tree are a scaled measure of the relationships between the speakers. The results of the study indicate the technique to be a promising method for the selection of a sample of speakers with perceptually different voices.
Identification of Heart Murmurs by Spectrographic Pattern Matching
Authors: Kersta L. G. , Schwartz M. L.
Published: November 2005

Skilled voiceprint-identification panelists achieved better than 80% success in the identification of heart murmurs produced by malfunctioning aortic and pulmonic valves. Present diagnostic procedures often confuse murmurs produced by the aortic and pulmonic valves necessitating confirmation by catheterizing, an undesirable surgical procedure. The success achieved by the pattern-matching technique may provide a means for eliminating the need for catheterizing in most cases involving these valves. The experiment involving 17 cases of valvular aortic and 24 cases of valvular pulmonic stenosis is illustrated and described. Preliminary success using automated strategies to identify these malfunctions is also discussed.
Bionics Approach to Speech-Pattern Recognition
Authors: Mundie J. Ryland
Published: November 2005

Research on speech-pattern recognition has been done using an electronic model of inner ear and nervous-system functions (Analog Cochlea and Middle C). Pulse patterns as they might occur in the nervous system at the level of primary auditory neurons can be sampled and displayed by the real-time digital data-processing system. The analog “auditory nerve” contains 18 channels. Typical pulse patterns for speech sounds from male and female voices have been recorded. Earlier investigations [J. Acoust. Soc. Am. 38, 934 (1965)] indicated that part of speech recognition is done on individual glottal pulse periods. This paper is an evaluation of the ability to identify discrete glottal pulses by their “neural” pulse signatures.
Dimensions in the Spectra of Speech Vowels
Authors: Plomp R.
Published: November 2005

Traditionally, the formant frequencies are regarded as the most important characteristics of the frequency spectra of vowels. It is possible, however, to approach the discrimination between vowel spectra in a more general way by considering the sound-pressure level in each of a number of passbands as a coordinate in a multidimensional Euclidean space, so that different vowels result in different points in this space. Frequency spectra of 15 Dutch vowels were determined with 18 bandpass filters and the data of 10 speakers were averaged. Computations showed that 96% of the variance of the 15 points could be explained by 4 new coordinates; these coordinates are linear combinations of the 18 original ones. By means of a rather simple apparatus, it is possible to visualize the two main dimensions by the position of the light spot of a cathode-ray tube, in such a way that the position of the spot depends upon the vowel uttered.
Is the Intelligibility of Alternated Speech Related to Rate or Place of Alternation?
Authors: Hughes George W. , House Arthur S. , Goldstein D. P. , Rupf John A.
Published: November 2005

As part of a study of linguistic factors in the perception of time-distorted speech, we have performed some preliminary experiments in which listeners were asked to repeat (i.e., shadow) speech presented alternately to each ear. Huggins [J. Acoust. Soc. Am. 36, 1055–1064 (1964)], has suggested that the interfering effects of alternation should be attributed to some characteristic of the speech signal and are not inherent in the auditory system; he found minimal repetition scores when speech was alternated periodically between listeners' ears at a critical rate in cycles per second close to 80% of the talker's average syllable rate. Our experiments evaluated subjects' performance when shadowing speech alternated periodically and when shadowing speech switched synchronously with syllables. Results showed that when alternation was locked to the syllables errors in shadowing were twice as frequent as when alternation was periodic at Huggins' critical rate. These findings indicate that syllabic structure of the speech signal cannot be time-altered without serious consequences to perception; distortion of other linguistic units may prove to be equally disturbing. [Research supported in part by the Air Force Cambridge Research Laboratories.]
Breathing Mixture and Depth as Separate Effects on Helium Speech
Authors: Gerstman Louis J. , Gamertsfelder George R. , Goldberger Arnold
Published: November 2005

Two divers made tape recordings of standard vocabularies while breathing several different helium-oxygen mixtures in a decompression chamber maintained at various simulated depths between sea level and 600 ft. Spectrographic analyses confirmed previous reports of nonlinear formant-frequency shifts and changes in relative formant amplitudes, but failed to reveal improvements with time in talker intelligibility, especially at the lowest depths. A mathematical model, incorporating both the effects of helium concentration and of depth, was found to account successfully for the observed changes in formant frequencies. The model has also been employed in a real-time speech correction device, the output of which represents a significant improvement in helium-speech intelligibility. [Work supported by Ocean Systems, Inc.]
Integral-Transform Formulation of Sonar-Aperture Theory
Authors: Brown D. H. , Folds D. L.
Published: November 2005

A study was undertaken to develop a mathematical formulation of a generalized sonar system. It has been found that an active sonar system may be described in terms of three general apertures. These are the illuminating aperture (projector), the effective aperture formed by the insonified area of interest, and the receiving aperture. Integral-transform theory has been used to describe the complex wavefront reflected from the insonified area of interest. The resulting mathematical formulation is general and allows any active sonar system to be described in the same terms. The importance of such a unifying description is demonstrated by analyzing three techniques for processing the complex wavefront intercepted by the receiving aperture. Two of these techniques are conventional integrating arrays and imaging systems. In imaging systems, a lens or reflector is used to transform the incoming wave into an acoustic image. It has been found that the integrating array is a highly specialized imaging system. A third technique that has been analyzed is a new and promising method that uses holographic techniques to reconstruct an optical image of the area of interest from the incident acoustic wavefront.
Wave Propagation in a Sandwich Ring
Authors: Sagartz M. J. , Keer L. M. , Herrmann G.
Published: November 2005

Using a Timoshenko-type theory for a sandwich ring, an equation is developed giving the phase velocities for the different types of wavemotion present. Approximations to the theory are given when the neutral axis is inextensible. A further approximation is given when the wavelength of the motion is long and the curvature is slight, by neglecting the rotatory inertia term in the Timoshenko theory. Taking typical values for sandwich materials, curves are drawn showing the effects of these approximations. Curves showing group velocity versus wavenumber are also given. The transient response of a ring to concentrated loads representing a delta function and a step function in time is studied using this theory. Three different wave-propagation speeds are noted for the wavefronts and an asymptotic expression valid near each wavefront is given.
Loss of Differential Pressure (SPL of Tympanic Cavity re SPL External Auditory Meatus) as a Factor in Eardrum Perforations
Authors: McArdle Florence E. , Tonndorf Juergen
Published: November 2005

This study attempts to treat the problem of sound transmission by a perforated eardrum in the general context of middle-ear mechanics. Work with a “model” of the eardrum and bulla cavity suggested that a sizeable percentage of response loss was due to partial cancellation of directly incident pressure, as sound pressure gained access to the back of the tympanic membrane through a perforation. Wever and Lawrence (1954) and Kobrak (1959) had suggested a similar factor. The present experiments attempted to determine its magnitude. Cochlear-microphonic (CM) responses to air-conducted pure tones were recorded from the round window of acute cats. Sound-pressure levels corresponding to the 10-μV CM were measured both in the external canal and in the tympanic cavity. The following experimental conditions were systematically varied: driving system, open/closed; bulla, open/closed; eardrum, intact/perforated. From comparisons among these conditions, data were derived to represent the loss of differential pressure due to a perforation of given dimensions. [Work supported by grants from the National Institute of Neurological Diseases and Blindness, National Institutes of Health, U. S. Department of Health, Education and Welfare.]
Network Analog of Bone Conduction
Authors: Tonndorf Juergen
Published: November 2005

Earlier experiments in animals, cadaver heads, and cochlear models gave evidence for a number of factors contributing to bone-conduction responses [Acta Otolaryngol., Supplement No. 213 (1966)]. Based upon that evidence, a schematic impedance network of the bone-conduction mechanism has been constructed. It indicates that there are three signal pathways: soft tissues, bone, and skull contents; and three responding components that act as independent inputs: the walls of the external canal, the ossicles, and the perilymphatic spaces. The latter are interconnected by a response line and affected by a number of modifying factors—(a) the air column in the external canal with its external opening, (b) the air bubble in the middle ear, (c) the tympanic membrane, (d) the oval and round windows, and (e) the so-called 3rd cochlear window, the sum total of all communications between the cochlear spaces and the skull interior. [Work supported by grants from the National Institute of Neurological Diseases and Blindness, National Institutes of Health, U. S. Department of Health, Education, and Welfare.]
Ultrastructure of the Basilar Papilla in the Bullfrog
Authors: Frishkopf Lawrence S. , Flock Åke
Published: November 2005

The basilar papilla is one of two auditory organs found within the inner ear of most species of amphibians. It is thought to be homologous to the cochlea of higher vertebrates. We have used the techniques of light and electron microscopy to study this organ. The papilla is a short, cartilaginous, tubular extension of the saccule, terminated at the end by a thin, flat, contact membrane that separates the endolymphatic and perilymphatic spaces. Hair cells and supporting cells are arranged semicircumferentially in parallel rows along a portion of the tube. The tectorial membrane hangs from a cord that spans a diameter of the tube. From the surface of each hair cell there projects a bundle of sensory hairs, consisting of a number of stereocilia and a single kinocilium located at one side of the bundle. All hair cells are oriented in the same direction: the kinocilium is located at that side of the hair cell nearest to the contact membrane. About 350 myelinated nerve fibers innervate approximately 60 hair cells. Only one type of synapse has been found, an afferent connection between hair cells and nerve terminals. Notably absent are synapses of the sort commonly associated with efferent innervation.
The Effect of Sodium Deficiency on Cochlear Potentials
Authors: Konishi Teruzo , Kelsey Elizabeth
Published: November 2005

The scala vestibuli and/or scala tympani in guinea pigs were perfused with Na+ free Locke's solution, in which NaCl was replaced with either choline chloride or sucrose. Cochlear microphonics (CM), summating potential (SP), action potential (AP), and endocochlear potential (EP) were recorded from the basal turn before, during, and subsequent to, the perfusion. Complete replacement of the perilymph with Na+-free solution did not alter EP and CM immediately, although AP was abolished rapidly. Lack of Na in the perilymph of scala tympani depressed AP more markedly than did a comparable deficiency in scala vestibuli. In most cases, the depression of AP was reversible and EP and CM showed a gradual decline after the perfusion. These data were further confirmed by the fact that tetrodotoxin at a concentration of 50λ/l did not modify EP and CM, although AP was abolished promptly. The mechanism underlying the generation of the receptor potential is discussed. [Work supported by National Institutes of Health, Public Health Service, U. S. Department of Health, Education and Welfare.]
Transient Responses from the Cochlea of the Pigeon
Authors: Stopp Phyllis E. , Ross H. F.
Published: November 2005

Records of the summating potential (SP) obtained with high resolution from the scala tympani of the pigeon consistently show the presence of transients corresponding to both the onset and termination of a tone pulse. The ON transient is of the same polarity as the SP (negative with respect to scala media), while the OFF transient is of opposite sign and is usually greater in magnitude and duration. When the rate of onset or decay of the tone is reduced by utilizing ramp stimuli, the transients are decreased, but may not be completely abolished with rise and fall times as long as 1 sec. Stimulation of the olivocochlear bundle in the floor of the 4th ventricle sufficient to abolish the gross neural response enhances the transients as well as the sustained SP.
Scattering by Penetrable Prolate Spheroids
Authors: Yeh C.
Published: November 2005

Most previous theoretical analyses were carried out with the assumption that the scattering object was either an elastic sphere, an elastic cylinder, or a rigid spheroid. Because of the importance of the penetrable spheroid problem with regard to the scattering by nonspherical bodies, as well as its relevance to the scattering by various physical objects (such as submarines, whales, etc.), the task of solving this problem is carried out. Two specific problems are considered: (a) the scattering of acoustic waves by penetrable liquid prolate spheroids; (b) the scattering of acoustic waves by penetrable elastic prolate spheroids. Numerical results using the newly compiled tables of radial prolate spheroidal functions for Problem (a) will be presented. Analytical results will be given for Problem (b). The resonance region will be emphasized. [Supported by the Office of Naval Research.]