bluuebunny/crossref_metadata_2025 huggingface dataset:
Discriminability of Members of a Common Envelope Set
Authors: Feth Lawrence L.
Published: October 2005

Signals having identical envelope functions and bandwidths, but differing in instantaneous phase are said to belong to a common envelope set. The members of a common envelope set may be classified as minimum-phase or nonminimum-phase signals by the location of their zeros in the complex time plane. The simplest common envelope set contains only two members. Each is composed of two sinusoids separated in frequency by Δf and in amplitude by ΔP. These signals possess mirror-image power spectra, and it can be shown that they exhibit a minimum-phase, maximum-phase relationship. Three experienced listeners were asked to discriminate between these minimum- and maximum-phase signals in a two-interval forced-choice experiment. The percentage of correct discriminations as a function of Δf and ΔP is shown to be related to differences in a weighted average of instantaneous frequency. [Research supported by the National Institutes of Health, Public Health Service, U. S. Department of Health, Education, and Welfare.]
Simulation With One Shaker of Random Vibration Induced by Complex Excitation
Authors: Crenwelge O. E. , Muster D.
Published: October 2005

In order to assess the feasibility of using one electromechanical shaker to simulate the random vibration of structures which have been excited in service by complex excitation environments, an experimental study was conducted on two lightly damped structures having widely separated resonances in their lower frequency range, i.e., a cantilever beam and a simply supported rectangular plate. The complex random excitation environment was provided for the beam by two mechanical shakers and for the plate by acoustic noise. One properly located shaker, providing an appropriately shaped input force spectrum, was used to reproduce practicably the narrow-band response spectra and cross spectra for two measurement locations on each structure. The practical effects of attaching shakers directly to the structures are discussed. Comparisons made between the experimentally determined frequency-response functions and the theoretical values, corrected for shaker attachment effects, show good agreement. From the results, it is concluded that reproduction of the response spectral density at any one point on structures of this type assures reproduction with the same degree of accuracy of the response spectra at all other points and the cross spectra between each pair of points.
On the Dynamic Behavior of a Cable System in a Recovery Operation
Authors: Laura Patricio A. , Goeller Jacques E.
Published: October 2005

The removal of bodies embedded in the ocean-bottom sediments is a matter of great importance in ocean technology. A common occurrence takes place in the case of salvage recovery of large objects. Another example is the case of civil-engineering-type structures conceived for placement in the ocean floor since some degree of mobility is required for maintenance purposes. The present study deals with an experimental and analytical investigation on the behavior of a cable system in a salvage-type operation. Steady-state and transient vibrations of the system are considered. The possibility of “snap” loads in the system is studied and some conclusions of practical interest are drawn.
Vibration and Wave Propatation in Ribbed Plates
Authors: Rumerman M. L.
Published: October 2005

A general solution was obtained for the forced vibration of an infinite plate, periodically stiffened by identical uniform ribs. The ribs were idealized as parallel line attachments capable of exerting line forces and line moments upon the plate, and the magnitudes of these forces and moments were related to the motion of the plate through the impedances of the ribs and plate. The assumption of an externally applied pressure excitation, which varied harmonically in time and in the plane of the plate, permitted an explicit solution. The principle of superposition was then used to construct the solution to an arbitrary excitation. By setting the amplitude of the harmonic excitation equal to zero, an equation for the free modes of the ribbed plate was derived, which agreed with known limiting forms for low and high frequencies.
An Extension of the Dynamic Characterization Method in Predicting Level-Crossing Statistics
Authors: Lambert R. F. , Janssen R. A. , Dunens E. K.
Published: October 2005

The preceding paper utilizes an “equivalent system” approach to evaluate the response level-crossing statistics of complex linear systems subjected to impulsive noise excitation. In the past, attention has been directed toward situations where either the impulse-noise-density parameter γ is small, say less than unity, or very large, say greater than 10. In the former it was necessary to include only the effect of the most recently occurring impulse, while the latter could be modeled with Gaussian statistics amenable to theoretical analysis. In this work, the analysis is extended to intermediate values of γ by including the effects of all of the preceding impulses in an approximate way. New analytical expressions are derived for the response level crossings. Empirical level-crossing data from a single-degree-of-freedom system is presented that shows this new approach to be promising with the theoretical results providing an upper bound on the data. Empirical studies on systems with several degrees of freedom also show the power-weight method “equivalent system” approach developed for γ < 1 to be valid for values of γ as large as 10. Thus, one can now utilize dynamic characterization to analyze conveniently the level-crossing problem for a wide class of impulsive noise problems. [Work supported by grant from the National Science Foundation.]
Perceptual Competition between Speech and Nonspeech
Authors: Day Ruth S. , Cutting James E.
Published: October 2005

In contrast with previous dichotic listening experiments that delivered either two speech messages (speech/speech) or two nonspeech messages (nonspeech/nonspeech) on each trial, the present study used mixed trials: speech to one ear and non-speech to the other ear (speech/nonspeech). The relative onset time of each dichotic pair was varied over a ±200-msec range. Subjects were asked to report which stimulus began first on every trial. Processing Time: If, according to a speech mode hypothesis, there is a set of processors specialized for speech, then speech stimuli might well require more processing time than nonspeech stimuli. The data support this view: subjects accurately reported hearing a nonspeech stimulus first when it led by a small time interval, whereas they were unable to determine that a speech stimulus began first unless it led by a much greater interval. Ear Advantage: Other studies have found a right-ear superiority for speech/speech presentations and a left-ear superiority for nonspeech/nonspeech. Instead of finding a superiority of an ear for its “proper” type of stimulus, the current study obtained over-all left-ear performance that was more accurate than right-ear performance. The study suggests that there are different mechanisms for the perception of speech and nonspeech.
Judgments of Similarities among Initial Consonants Using an Auditory Sorting Apparatus
Authors: Pruzansky Sandra
Published: October 2005

Subjects used a computer-controlled sorting apparatus to initiate the presentation of 16 different consonant sounds, each followed by the vowel /a/. Each subject arranged 16 pegs, which assessed the auditory stimuli, on a 16×16-hole board so that the distances between pairs of pegs reflected the similarities of the corresponding consonant sounds, i.e., the closer the pegs, the more similar the sounds. It was assumed that each subject's arrangement would include both information about the relative importance of attributes of the stimuli and noise, owing to incomplete checking of all 120 interstimulus distances. Euclidean distances in the subjects' arrangements served as input to the Carroll-Chang INDSCAL program [Psychometrika (1970) (to be published)]. The resulting group stimulus space revealed a separation between continuants and stops. Nasals were clustered. Pairs of stops differing only in voicing were grouped together.
The Perception of Changing Fundamental Frequency
Authors: Lehiste Ilse
Published: October 2005

Very little information is available regarding the perception of changing fundamental frequency. The present paper deals with the perception of the difference between the initial frequency and the terminal frequency of a rising-falling fundamental-frequency contour. The synthetic vowel /a/ was produced at two fundamental-frequency ranges (163–200 Hz and 86–115 Hz) with identical initial and peak frequencies, but different terminal frequencies, half of which were higher than the beginning frequency and the other half lower than the beginning frequency. Listening tests were carried through with native speaker of American English and native speakers of a tone language (Serbo-Croatian). The speakers of Serbo-Croatian were asked to make a linguistic judgment; the speakers of American English made a phonetic judgment. It was found that under conditions in which high-pitched and low-pitched stimuli were randomly mixed, both groups of listeners tended to identify the higher-pitched stimuli as rising and the lower-pitched stimuli as falling, regardless of the actual differences between their initial and terminal frequencies. The linguistic judgments were not categorical in nature. Some implications of these results are discussed.
Simultaneous and Time-Staggered Dichotic and Monotic Speech Perception after Circumscribed Temporal Lobe Lesions
Authors: Berlin Charles I. , Lowe Sena S. , Leslie Gail W.
Published: October 2005

At previous meetings of this Society (November 1969, April 1970), we reported that when stimuli are lagged in the dichotic mode, normal listeners perceive the lagging stimulus better than the leading stimulus between 30 and 90 msec. We have studied patients with circumscribed temporal lobe lesions under these conditions and have observed: (1) No lag effect; the contralateral ear to the lesion does more poorly at simultaneity as well as at time staggers out to 500 msec. (2) When the words compete monotically, a laterality effect can also be seen in which the contralateral ear to the lesion does more poorly in reporting monotic competing messages. (3) Data suggest that the patients behave “monotically” with respect to two-ear stimulation when one temporal lobe has been compromised. (4) As recovery takes place, differences between the ipsi-lateral and contralateral ear get larger, implying further asymmetry developing between the hemispheres. [This research was supported by NS-07095.]
Perception of Language and Nonlanguage Sounds: Evidence for Unilateral Brain Function
Authors: Spellacy F. , Blumstein S.
Published: October 2005

Subjects were presented with a series of single dichotic pairs of melodies and sound effects (N = 58) or words (N = 58). In an earlier paper, these sounds were shown to have created a language and a nonlanguage set which produced both a right-and a left-ear superiority of vowel recognition. Changes in performance due to set occurred at the right ear only. In the present study, identification of set producing sounds was superior at the right ear for language and at the left ear for non-language sounds. Subjects receiving both language and non-language sounds in this experiment (N = 58) and in a previous experiment (N = 64) showed that the degree of lateral preference shown for language and nonlanguage sounds was negatively correlated. It is suggested that ear differences caused by language set, like those which have been attributed to bilateral asymmetry of brain function, may be accounted for by a unilateral asymmetry of brain function involving the left hemisphere.
Speech Processes in Syllable Recall
Authors: Nakatani L. H.
Published: October 2005

A new method for evaluating speech quality was investigated to supplement articulation tests. Subjects recalled a single target syllable from a randomized list presented at various rates. The target syllable either immediately preceded or followed a predesignated cue syllable which occurred at random serial positions. Results: (1) recall deteriorated as rate increased; (2) this deterioration was more pronounced when the target preceded the cue; and (3) serial position had a negligible effect on recall. These results suggest that, when the target precedes the cue, subjects attempts to recognize and encode into memory each syllable before the next one occurs. Encoding, which is essential for recall and which apparently cannot proceed in parallel with recognition, may be interrupted when the next syllable arrives and requires recognition. Such interruptions reduce recall and occur more often as recognition time increases. If recognition time increases as speech quality declines, then the recall level in the target-cue condition should be a sensitive measure of speech quality. Apparently subjects do not alternate between recognition and encoding in the cue-target condition, thus precluding the interruptions from which recognition times are inferred.
Enhancement of Heat Pulses in Crystals Due to Elastic Anisotropy
Authors: Maris H. J.
Published: October 2005

The generation of thermal acoustic waves by a heated metallic film on the surface of a dielectric crystal at low temperatures is discussed. It is shown that even if the waves produced correspond to a uniform distribution of directions of wave vector, there may be a large enhancement of energy flow in some crystallographic directions compared to the average. This effect arises because of elastic anisotropy. Explicit expressions are given for the enhancement expected in the principal directions of cubic crystals. [Supported in part by the National Science Foundation.]
Office Machine Noise Control
Authors: Teplitzky Allan M.
Published: October 2005

High-speed printing or punching mechanism in office machines may result in unsatisfactory noise environments in offices. To improve the acoustical environment, machine users are faced with reducing the machine noise without altering the machine mechanisms or noise sources. Two noise reduction options available are (a) improving the noise reduction of the machine cover, and (b) the installation of partial or full enclosure around the machine. This paper discusses some case histories in which the merits of these two approaches have been investigated.
Sound Transmission Loss of Complex Single Panels
Authors: Holmer Curtis I.
Published: October 2005

Frequently, the transmission loss of panels must be estimated from limited data for use in design problems. Usually, the panels involve complex constructions where the assumptions of single-panel theory cannot be reasonably applied. A simplified analysis of the dynamics of some complex panels is presented which leads to a straight-forward prediction scheme based on modifications of the forced wave transmission loss of a single homogeneous panel. Details of the analysis and comparisons with experiment are provided for the homogeneous panel, two- and three-layer panels, orthortropic panels, and ribbed panels.
Circular Versus Linear Path Averaging in Reverberation Rooms
Authors: Lubman David
Published: October 2005

Spatial averaging is required for the measurement of pure-tone sound power ia reverberation rooms. The aim is to achieve a low-variance estimate of the room-average-squared sound pressure. The variance depends on the shape of the averaging path as well as its length. For continuous averaging over straight-line paths a formula for variance has been reported [J. Acoust. Soc. Amer. 46, 532–534 (L) (1969)]. These results are extended to circular paths, which are commonly used for practical reasons. The variance for a circular path is derived and compared with a linear path of equal length. Circular path variance is always higher (less favorable). The discrepancy is greatest for path lengths of 34 wavelengths, where the circular path variance is 41% higher. However, for traverses that are either very long or very short, the two variances are nearly equal. [This work sponsored by the Office of Naval Research.]
Parametric Sonar Transmitting Array Measurements
Authors: Mellen R. H. , Browning D. G. , Konrad W. L.
Published: October 2005

Experimental results of intensities and beam patterns of a parametric sonar transmitting array are presented. For a mean primary frequency of 720 kHz and secondary frequency of 50 kHz, source levels up to 90 dB re 1 μbar at 1 m are attainable. At this level, however, saturation effects broaden the beamwidth to 8°, whereas the unsaturated condition produces a beam width of 3°.
A Method of Selecting Element Positions in a Hydrophone Array to Reduce Minor Lobes
Authors: Kendig Paul M.
Published: October 2005

It is shown that if the sensitivities and resonant frequencies of elements in a hydrophone array can be accurately determined before they are placed in an array, it is possible to select their positions in the array that should significantly reduce minor lobes. An expression for the sensitivity of an individual element that depends on easily and accurately measured quantities has been derived. The variation in phase depends primarily on the resonant frequencies of the elements if element positions can be held to sufficiently close tolerances. Comparisons of calculated results are made with experimental measurements and with computed results of random placement of the transducer elements.
Application of Linear Programming to the Synthesis of Optimum Directional Patterns from Arrays of Point Elements
Authors: McMahon G. W. , Hubley Barbara , Mohammed A.
Published: October 2005

The techniques of linear programming have been applied to the synthesis of optimum directional patterns from arrays of point elements. A practical linear model of the problem can be formulated by dealing with the real and imaginary components of the directivity function. The size and geometry of arrays that can be treated by this approach are limited only by computation time and computer storage requirements. Numerical examples are given for arrays of up to 70 elements.
Dynamics of Magnetostrictive Ring Transducers
Authors: Wilkinson J. P. D.
Published: October 2005

A numerical approach is presented for calculating the dynamic behavior of magnetostrictive transducers in the shape of a shell of revolution (for example, a cylindrical ring). The method accounts for the effects of saturation and loss, which are important in magnetostrictive devices, and is applicable to either biased or unbiased transducers. The most significant effect is the generation of response harmonics at frequencies that are integral multiples of the fundamental driving frequency. Since most transducers of this type are of a laminated scroll construction, the effects of the alternating layers of magnetostrictive material and epoxy bond are included.
Particle Velocity Profiles in Underwater Horns
Authors: Mathis T. D. , Finch R. D.
Published: October 2005

Particle velocity profiles in underwater horns were measured using a pressure gradient hydrophone. This device consisted of a ceramic bender mounted in silicon rubber in an open-ended brass cylinder. The largest diameter of the hydrophone was 1 in. so that it was suitable for velocity measurements at frequencies below about 5–10 kHz. The hydrophone was used to probe the mouth of an underwater horn. A possibility of a correlation between the velocity profiles at the mouth and farfield directivity index was examined.
Variable-Focus Liquid-Filled Hydroacoustic Lens
Authors: Knollman G. C. , Bellin J. L. S. , Weaver J. , Hartog J. J.
Published: October 2005

A large, fluid lens, with accompanying reservoir and pump arrangement, is described for underwater acoustic-imaging purposes. The liquid lens provides better acoustic transmissivity and lower sound absorption than does a comparable solid lens, and has an equivalent acoustic refractive index. Focusing of the liquid lens is achieved without physical motion of the lens by changing the radii of curvature of the membrane surfaces, in a manner analogous to the operation of the human eye. Pertinent properties are cited of the neutrally buoyant lens fluid, the elastomeric lens membrane material, and the composite lens. Theoretical consideration gives the stretched-membrane surface configuration, which is shown to be approximately spherical. The standard spherical lens equations are combined with appropriate mensuration formulas to obtain evaluation and calibration equations. A hydroacoustic image taken with the liquid lens is displayed and compared with that formed by an equivalent Plexiglas lens. The features of appropriate apodization and immunity to wave action are noted. [Supported by the Naval Ship Systems Command.]
Unidirectional Microphones
Authors: Sessler G. M. , West J. E.
Published: October 2005

A unidirectional microphone based on the gradient principle employing a tube arrangement for sampling the sound field has been designed. The system is a second-order gradient receiver [G. M. Sessler et al., J. Acoust. Soc. Amer. 46, 28 (1969)], utilizing a single foil-electret transducer. A Helmholtz resonator, comprising the tubes and cavities surrounding the transducer, is tuned to the lower end of the frequency range to compensate the ω2 dependence of the second-order gradient design and to improve the over-all signal-to-noise ratio of the microphone. Measurements show that the microphone sensitivity in a plane through the rotational axis obeys approximately the expected (1+cosφ) cosφ law, where φ is the angle relative to the rotational axis. The calculated directivity factor is 8.7 Db. The equalized frequency response in the plane of maximum sensitivity was measured to be within ±2.5 Db from 0.25 to 3 Khz with a sensitivity of about −6 Db V/μbar. Because of their large directivity factors, such unidirectional microphones may find application in environments with high noise levels.
The Behavioral and Histological Effects of Auditory Over-exposure on the Cat
Authors: Dolan Terrence R. , Bredberg Goran , Ades Harlow W. , Neff W. D.
Published: October 2005

The behavioral and histological effects of overstimulation on the auditory system of the cat are being examined. Thus far, the exposure stimuli considered have been tones between 125 and 4000 Hz at several stimulus intensities and durations. Stimulation levels have been varied from 120 to 160 dB SPL, and durations between 1 and 4 h have been examined. One of the initial results is that the amount and locus of damage resulting from exposure and the associated effects on audibility are most difficult to predict at low exposure frequencies. At 125 Hz, for example, seven animals have been exposed for 4 h at intensities between 150 and 160 dB SPL. The exposure caused either no apparent damage and no associated hearing loss or almost total damage along the entire length of the cochlea and nearly complete hearing loss. These and other results from exposure frequencies of 1, 2, and 4 kHz will be described. [Research supported by a grant from the National Aeronautics and Space Administration.]
Rapid Acquisition in Monkeys of an Auditory Location Discrimination
Authors: Downey P. , Harrison J. M.
Published: October 2005

Monkeys require a considerably larger number of trials to bring responding under the control of the location of an auditory stimulus than cats, rats, and bats when the same experimental procedures are used. This experiment investigated the conditions necessary for rapid acquisition of control of responding by location of sounds in the monkey. Monkeys were run in an enclosure which contained four loud speakers and four manipulanda. Two conditions were used in training. In the adjacent condition, a stimulus (noise or tone burst) was presented through one or other of two speakers and a response on the manipulandum adjacent to the speaker was reinforced with food (correct response). In the nonadjacent condition, a stimulus was presented through one of two speakers and a response on a manipulandum remote from the speaker was reinforced with food (correct response). Acquisition of control was measured by change in the percentage of correct responses during training. In the adjacent condition, responding came under control of location of the stimulus within zero to three sessions. In nonadjacent conditions the animals required 14 to 20 sessions. These latter numbers are comparable to those reported in the literature for localization discrimination in monkeys. [Supported by National Science Foundation Grant and The Graduate School of Boston University.]
Auditory Localization: The Role of the Trapezoid Body
Authors: Casseday J. H. , Neff W. D.
Published: October 2005

The effects of transection of the tapezoid body upon the cat's ability to localize sound were investigated. Four cats were trained to localize pulses of broad-band noise in a free-field situation, and their thresholds for minimal detectable angle were determined. After transection of the trapezoid body, each animal was tested for retention of the localization habit. Two animals retained the localization habit and showed little or no loss in threshold for localization; the other two failed to retain the habit and were unable to relearn to localize. Other auditory tests on the latter two animals indicated that they could learn to respond to a sound signal and that they could learn to discriminate between tonal patterns (high-low-high versus low-high-low). Electrophysiological records, obtained from each cat after testing was completed, showed that evoked potentials could be obtained from auditory areas of the cerebral cortex when click stimuli were presented to the ear. A comparison of the anatomical evidence for animals that retained the localization habit and those that were unable to relearn suggests that the anterodorsal portion of the trapezoid body may be crucial for localization. [This research was supported by the National Science Foundation.]
Acoustic Information Denial as a Means for Vertebrate Pest Control
Authors: Crummett J. G.
Published: October 2005

Field observations have been made of bird, deer, and rabbit behavior while exposed to an acoustic jamming signal. When such a signal is broadcast into an area, wildlife retreat to a zone of lesser signal intensity. The signal is composed of two different frequencies at about 2 and 4 kHz, which are frequency and amplitude modulated at rates compatible with neural time constants so as to maximize jamming efficiency and minimize adaptation. Results of over 300 installations in the United States, Canada, and Europe demonstrate the usefulness of the technique as a control measure. Comparison with other control techniques such as playback of alarm and distress cries and other fright-producing acoustic methods indicate that effectiveness and nonhabituation are the main advantages.
Acoustic Horns with Spatially Varying Elasticity or Density
Authors: Shaw E. A. G.
Published: October 2005

The transformation of acoustic impedance can be accomplished either by a controlled variation of wavefront area as the wave progresses, or by transmission of the waves through a medium in which there is a gradient of elasticity or density. The second concept does not seem to have been exploited despite the fact that the effective density of a fluid medium can be increased by introducing suitable arrays of obstacles, and the bulk modulus of a liquid decreased by compliant inclusions. Analysis shows that, for plane waves, a medium in which density varies as (C+mx)−2 or elastic modulus as (C−mx)2, where x is distance and C and m are constants, is analogous to the familiar exponential horn. Simple analytical solutions have also been found for radial variations of density of elasticity which transform the behavior of sectoral and conical horns into acoustic equivalents of exponential horns. Since the wave equation is separable in both cylindrical and spherical coordinates, these solutions are exact.
Application of Modified Ray Theory to Underwater Sound Propagation
Authors: Murphy E. , Davis J. , Doutt J.
Published: October 2005

At frequencies of a few hundred hertz or less, diffraction effects can be significant for sound propagation in the oceans. A modified ray representation for some of these effects has recently been developed [Murphy, J. Acoust. Soc. Amer. 47, 899–908 (1970)—unbounded problem; Davis and Murphy, this A. S. A. meeting—boundary problem]. The method applies to propagation through regions of local sound-velocity maximum, and for rays reflected or refracted away from a boundary region with velocity profile monotonically decreasing away from the boundary. In this paper, velocity profiles are considered, varying only with depth, composed of nearly linear and nearly parabolic segments joined with continuous derivative. In this way, modified ray analysis covers a wide class of realistic profiles pertinent to underwater sound propagation. Modified ray analysis is most conveniently formulated as wavelength-dependent “ray displacement” and “leakage” phenomena. Ranges for displaced rays (at given receiver depth) versus ray parameter (angle at source) are presented for unbounded examples and for profiles bounded by pressure release or rigid surfaces. Leakage coefficients are included for the unbounded examples. Unlike ordinary ray representations, modified rays are not sensitive to small changes in profile.
Acoustical Fluctuations Correlated with Ocean Movements over One Deep-Ocean Skip Distance
Authors: Beckerle J. C. , LaCasce E. O.
Published: October 2005

Fluctuations in sound velocity at a depth of 560 m below R/V CHAIN were measured for 33 consecutive hours. R/V CHAIN was stationed at the second turning point of a single deep-ocean skip-distance (RSR) soundpath. The oceanographic observations exhibit some visual correlation with the amplitude fluctuations of acoustical pulses (data supplied by H. Broek, Bell Telephone Laboratories). The sound source at a depth of 834 m was suspended below a ship located 83 km from the receiving hydrophone, which was at a depth of 1460 m. Examination of the large- and small-scale acoustical fluctuations in comparison with the oceanographic observations seems to indicate that the acoustical pulse amplitudes increase when the sound velocity at 560-m depth varies about some mean value. These sound-velocity variations are related to internal waves which produce variations in the depth of the knee of the very thick isothermal layer characteristic of the area near Bermuda in April.
Listener Performance in a Speaker Verification Task
Authors: Rosenberg A. E.
Published: October 2005

A comparison has been made between the performance of a computer procedure of speaker verification [Doddington, J. Acoust. Soc. Amer. 49, 139(A) (1971)] and listener performance in the same task. In the evaluation of the computer method, 32 “casual” impostors were pitted against eight “true” speakers. A “casual” impostor is one who makes no attempt to mimic the “true” speaker but simply repeats the same test sentences in his own natural voice. After an a posteriori adjustment of the acceptance-rejection criterion to equalize errors of false acceptance and false rejection, an average error rate of 1.5% is obtained. The same test utterances used by Doddington were used as stimuli in a subjective speaker verification experiment in which 10 listeners participated. Each stimulus presentation was a paired comparison consisting of a challenge and a reference utterance. The reference was one of the “true” speaker utterances while the challenge was either an utterance from the same “true” speaker or an “impostor” utterance with equal likelihood. Listeners were required to indicate whether they thought the utterances were by the same or different speakers. The over-all average error rates were approximately 4.2% for both false acceptance and false rejection. The best false acceptance rate by an individual listener was 1.6%, while the best individual false rejection rate was 0.5%.
Speech Compression by Component Selection in the Frequency Domain
Authors: Luck J. E. , Manley H. J. , Shaffer H. L.
Published: October 2005

In the experiment described in this discussion, digital speech compression was achieved by dividing the speech signal into contiguous 256 sample segments, transforming each to the frequency domain with an FFT, preserving the magnitude and phase of the N largest components while setting all others to zero, and transforming the modified data back to the time domain by an inverse FFT. Samples of speech for different values of N will be played to show that, with only one-fourth of the frequency components preserved, speech is produced that is nearly indistinguishable from the original. Pitch is accurately preserved as N is reduced, but gradually discontinuities at the junction of segments and beeps due to isolated components become audible. Other manipulations of the data can easily be performed in the frequency domain to determine what data are perceptually significant. Some of these, such as variation of quantization accuracy, manipulation of phase, and component elimination or insertion, are discussed. Coding for transmission must include the magnitude and phase as well as the location of the selected components.
A High-Quality Channel Vocoder
Authors: Larkin W. D. , Stewart L. C.
Published: October 2005

A speech ayalysis-synthesis system which preserves the natural quality of the speaker's voice has been implemented on a general purpose computer. The analyzer is routinely implemented using a 30-msec Hamming window, and a 512-point fast Fourier transform is obtained every 10 msec. Since the speech input to date is of high quality, conventional energy balance voice-unvoice detection is used, and the pitch is obtained by determining the frequency of the first harmonic component. Channelization of the spectrum information is achieved by summing adjacent spectrum components to obtain 36 contiguous channels equally spaced from approximately 100 to 4800 Hz. Similarly, a 16-channel version is constructed using the components from approximately 200 to 3800 Hz, but the channels are not equispaced at the higher frequencies. Comparison between the 36-channel version and the 16-channel version shows little difference in quality. The system function for the synthesizer was designed giving careful consideration to the literature of C. M. Rader and R. M. Golden. The synthesizer technique used is considered feasible for hardware implementation. A demonstration magnetic tape recording is presented.
The Pitch Shift of the Residue Produced by Complexes Having Component Sinusoids below 1000 Hz
Authors: Patterson Roy D.
Published: October 2005

Any set of three adjacent harmonics of 200 Hz falling within the frequency range 1200–2200 Hz will produce a 200-Hz residue pitch. When the components of such a set are shifted in frequency by up to 100 Hz, there is a proportional shift in the pitch of the residue (De Boer, 1956; Schouten, Ritzma, and Cardozo, 1962). The proportionality constant relating the pitch shift to the frequency shift increases from about 0.10 to 0.15 as the lowest component in the complex decreases from 2200 to 1200 Hz. They were unable to measure the pitch shift of the residue when the lowest component was below 1200 Hz. Using six and 12 component stimuli, which produce a stronger residue pitch, we extended this lower limit to 100 Hz. We found that the relationship between the pitch shift and the frequency shift remains linear. The proportionality constant rises to 0.20 as the lowest component in the complex moves from 1200 to 800 Hz, but below this point it does not rise further. [Research supported by the National Institutes of Health, Public Health Service, U. S. Departmnet of Health, Education, and Welfare, and by a reserach grant awarded to the Centre for Human Information Processing.]
The NECI: A Personal Noise Exposure Dosimeter
Authors: Sullivan C. E. , Knowd M.
Published: October 2005

In order to evaluate the exposures of persons who must work in intermittent or time-varying noise, the Noise Exposure Computer Integrater (NECI) has been developed. The A-weighted sound level is transformed to an integrated voltage that drives a display counter; the speed at which the counter operates is such that a reading of 100% is reached after 8 h of cumulative exposure at 90 dBA, and this speed doubles with every 5-dB increase in level, in accordance with the provisions of the Walsh-Healey Act and PL 91–596. An associated calibration device for the 20-oz NECI is described, and statistics on its reliability are presented.
Macrosonic Drying
Authors: Fairbanks Harold V.
Published: October 2005

This paper outlines the theories which have been proposed to explain the effect of the increased drying rates produced by macrosonics. Recent work by K. Seya on macrosonic drying and by W. I. Chen on the macrosonic stimulation of liquid flow through capillaries is discussed in view of extending the present theories on macrosonic drying. Highlights regarding studies on the macrosonic drying of fine coal at West Virginia University are also included.
Noise from Pile-Driving Equipment
Authors: Rosenberg Carl J. , Salter Charles M.
Published: October 2005

Urban noise ordinances show an increased public awareness of the deleterious effects of excessive noise levels in our environment. The noise generated by heavy construction equipment is often cited as a major offender. Restraints on these noise levels require several levels of compromise between the public, the law-enforcement agencies, contractors, and the clients of new constructions. As a particular example, the noise of pile-driving equipment has been investigated to evaluate possible trade-offs in resolving conflicts which may arise. The parameters and characteristics of noise from pile-driving equipment, factors controlling choice of equipment such as soil conditions and geography, and the economic consequences of various alternatives for noise reduction have been studied with an attempt made to outline a balanced approach toward evaluating this problem.
Some Experiments on Imploding Thin-Walled Glass Spheres Underwater
Authors: Peters R. J. , Stephens R. W. B.
Published: October 2005

Experiments have been performed to investigate the simulation of cavitation bubbles by the implosion of thin-walled glass spheres underwater. The bulbs were evacuated suitably gas-filled if necessary, sealed, and then fractured underwater. High-speed photography was used to study the implosion process and the radiated pressure waves were sensed by a hydrophone. The photographs revealed that the mode of collapse depended on the nature of the fracturing process. With a small impact, the glass is only punctured locally, and the glass appears to be fractured effectively by the inrushing water, giving rise to an unsymmetrical breaking. A more symmetrical fracture is obtained by using an externally generated shock wave. The possible buffering effect on the implosion of containing gas at appreciable pressure in a glass bulb was also investigated, together with the substitution of the surrounding water with a more viscous liquid. This type of experiment permits the variation and control of a number of parameters in the implosion phenomenon.
Syllable Structure and Sentence Rhythm—A Cross Language Study
Authors: Allen George , Ladefoged Peter
Published: October 2005

Differences in segmental structure between English, French, and Polish were examined to determine the effect of this structure on perceived rhythm. In conversational French the sequence VC♯CV́ is uttered as V♯CCV́; these sequences are not homophonous in English or Polish. Assuming that the rhythmic character of the second syllable of such a sequence depends very little upon segments preceding the juncture, then VC♯CV́ and V♯CCV́ should appear rhythmically similar in French but different in both English and Polish, whereas V♯CV́ and VC♯CV́ should be similar in both English and Polish, but different in French. Nonsense utterances containing VC♯CV́, V♯CCV́, and V♯CV́ sequences were produced by native English, French, and Polish speakers; other native speakers judged the rhythms of these utterances by tapping their fingers in time to the stressed syllables. Preliminary data suggest that (1) listeners “hear” the rhythm of an utterance more clearly when it is spoken by a compatriot than by a foreigner, and (2) listeners tend to perceive rhythmic structure in terms of their own linguistic rules, regardless of the language of the utterance.
Word-Unit Temporal Organization
Authors: Shockey L. , Gregorski R. , Lehiste I.
Published: October 2005

It has been observed that the word spoken in isolation can be defined in terms of its internal cohesion, that is, in terms of temporal compensation among its parts [I. Lehiste, J. Acoust. Soc. Amer. 48, 110(A) (1970)]. We conducted a similar experiment using a word with a different syllabic structure. The results agreed with those of the previous experiment. However, when the same word which we used in isolation was included in a sentence, a different temporal organization was manifested. We conclude that the word is temporally organized in terms of the size of the utterance in which it participates. It appears that the larger the utterance, the higher the linguistic level at which temporal compensation takes place.
Vowel Durations in Single-Syllable Words as a Function of Phrasal Context
Authors: Barnwell Thomas P. , Allen Jonathan
Published: October 2005

Previous studies have shown that vowel durations in English are a function of consonant environment, the vowel uttered, and proximity to junctural pauses, as well as stress when bisyllabic words in isolation are considered. The present study was conducted to study the effect of syntactic role on the vowel durations of monosyllabic words in simple three-word phrases. Three subjects read a list of 100 monosyllabic words in isolation, and 30 three-word phrases of varying structural composition. A model was devised which predicts the vowel durations observed as a function of the vowel, following consonant, phrasal position of the vowel, and the structural role of the word containing the vowel. This model successfully accounts for the durations observed for each of the three talkers, but must be normalized for each subject.
Tonotopic Organization of the Guinea Pig's Auditory Cortex
Authors: Walloch Richard A.
Published: October 2005

Only one study [Kayrers and Legouix, Compt. Rend. Biol. 157, 2161–2164 (1963)] mapped the auditory cortex of the gunea pig. In that study, two tonotopic areas were found. While one of these areas had a complete representation of the cochlea, the other area had only a partial representation. Since only three stimulus frequencies were used in that earlier study, the present study made a more complete map using 18 stimulus frequencies. The present data support the existence of the two areas previously reported. However, both areas appear to have complete representations of the cochlea. These data also suggest the possible existence of a third tonotopic area.
Acoustic Investigation of Leading-Edge Serrations on Lifting Surfaces
Authors: Hersh A. S. , Soderman P. T. , Hayden R. E.
Published: October 2005

There has been considerable interest recently in the application of leading-edge serrations to lifting surfaces as a means of reducing aerodynamically generated noise. The present study has been motivated by the unpublished work of Paul T. Soderman, who achieved a reduction of between 4–8 dB with serrations attached to the leading edge of a propeller. Soderman's studies were motivated by observations that owls, who fly extremely quietly, have upstream protuberances located on the leading edges of their wings. Using Soderman's results as a guide, we have attached a number of serrations to the leading edge of three two-dimensional airfoils and to two propellers. Substantial noise reductions were observed with these surfaces in a free jet. The experimental facility and an interpretation of the data are discussed. [This work has been sponsored by the NASA Ames Research Center under contract.]
Investigation of Aerodynamic Sound Radiation from Small Airfoils
Authors: Hersh A. S. , Meecham W. C. , Bies D. A.
Published: October 2005

In a recent paper, Clark and Ribner [J. Acoust. Soc. Amer. 46, 802–805 (1969)] show that the instantaneous sound radiated by an airfoil immersed in a turbulent flow and its fluctuating lift are connected by Curle's equation, which describes sound radiation from a rigid surface immersed in flow. Curle's equation furthermore states that for surfaces with characteristic dimensions small relative to the wavelength of the radiated sound, the fluctuating lift (and drag) may be modeled as point dipoles. An investigation has been carried out at the UCLA free-jet aerosonic facility to measure the sound directivity pattern of small airfoils in flow as a partial check of Curle's equation. The results of the investigation provide some evidence that, indeed, small airfoils in flow radiate like point dipoles in apparent support of that aspect of Curle's treatment. The experimental facility and an interpretation of the data are discussed. [This work has been sponsored by the NASA Ames Research Center under contract.]
Investigation of Supersonic Jet Noise Using Optical Holography
Authors: Salant Richard F. , Kolesar Robert R. , Zaic Gregory F.
Published: October 2005

Holographic techniques have been used to obtain three-dimensional visualizations of the noise field generated by a cold supersonic turbulent jet. Double exposure holographic interferograms of an underexpanded jet display conical fringes emanating from the jet, which are believed to be Mach wavefronts. These fronts appear to originate at disturbances on the core of the jet. Measurements of Mach angles indicate that the predominant convection velocity of the disturbances is approximately 80% of the jet velocity.
The Use of Acoustics To Generate and Detect a Gravitational Induction Field
Authors: Sinsky J. A.
Published: October 2005

The very near-zone dynamic Newtonion gravitational fields of an acoustically stressed cylinder were measured as a function of distance and azimuthal angle. The generator and detector were massive aluminum high-Q cylinders suspended in separate vacuum chambers. The experiment was performed at 1660 Hz, the fundamental longitudnal resonant frequency of the cylinders. The high frequency of 1660 Hz is a new regime for gravitational technology, since previously measured gravitational interactions were static, as in the Cavendish experiment, or at tidal cycles per day. The gravitational potential of the generator and the resulting excitation of the detector were calculated using Newton's theory of gravitation. Experimental results were in agreement with theory.
Finite-Amplitude Radiation from a Piston: Directivity of Harmonics
Authors: Blackstock D. T. , Muir T. G. , Lockwood J. C.
Published: October 2005

An application of the results given in the preceding paper (Lockwood and Blackstock) is made to the problem of the farfield finite-amplitude radiation from a baffled piston. The problem is solved merely by modifying the known solution for pure radial waves of finite amplitude. Let the latter be expressed as p = A (r0/r) Σ Bn(σ) sinn [ωt−k(r−r0)], where A is the amplitude at the radial coordinate r0 and σ is a stretched spatial coordinate such that σ=1 signifies shock formation [in particular, σ = β(A/ρ0c02)kr0 ln(r/r0); see, for example, D. T. Blackstock, J. Acoust. Soc. Amer. 39, 1019–1026 (1966)]. This solution is generalized to apply to the piston problem simply by substituting AD(θ) for A, where D(θ) is the farfield directivity factor given by linear theory. In the case of small distortions, Bn>σn so that the directivity of the nth harmonic is just given by Dn. When the distortion is greater, the directivity factors are more complicated. Experiments done in fresh water at low amplitude (source level 110 dB re 1 μbar) confirm the theoretical predictions for this case. [Work supported by Air Force Office of Scientific Research and Office of Naval Research.]