bluuebunny/crossref_metadata_2025 huggingface dataset:
Forward and Backward Masking: Testing a Discrete Perceptual-Moment Hypothesis in Audition
Authors: Robinson Charles E. , Pollack Irwin
Published: October 2005

A form of the discrete-moment hypothesis of Stroud, usually studied in relation to vision, is tested in audition by means of the masking of a click by a preceding or a following noise burst. Threshold masking and temporal psychometric functions suggest that, if a discrete-moment mechanism were operating, the time between successive moment onsets would be as short as 3 msec. Through a second-choice procedure, we attempted to distinguish between a continuous moment or signal detection class of hypotheses and the discrete-moment hypothesis. The results for one subject disagree with the prediction of the discrete-moment hypothesis.
Lateralization of Filtered Clicks
Authors: Yost W. A. , Wightman F. L. , Green David M.
Published: October 2005

Lateralization of brief clicks was studied while the frequency content of the clicks was altered by filtering. The subject was asked to discriminate a centered image, a pair of identical clicks that arrived simultaneously at the two headphones, from a displaced image, a pair of identical clicks in which the click to the left ear was slightly delayed. The discrimination of the lateral position deteriorated as the clicks were high-pass filtered beyond 1500 Hz and was largely unaffected by low-pass filtering. Masking with high-pass and low-pass noise showed that low-pass noise severely disrupted the lateralization of the high-pass clicks, but the high-pass noise produced no disruption of the lateralization of the low-pass clicks. Our results suggest that the discrimination of lateral position depends largely on the low-frequency content of the click and thus, presumably, on the apical end of cochlear partition.
Noise Reduction in Propeller Fans Using Porous Blades at Free-Flow Conditions
Authors: Chanaud Robert C.
Published: October 2005

Experiments were conducted on propeller fan blades at free-flow conditions to determine the noise reduction associated with the use of rigid porous materials as the blade material in lieu of solid material. The results suggest that significant sound reduction can be achieved with no loss of pumping efficiency when the pitch angle is increased from normal.
Application of Monopulse Tracking Techniques to Passive Linear Arrays
Authors: Roberts C. A. , Favret A. G.
Published: October 2005

This paper considers the bearing estimation performance of a monopulse processor for passive linear arrays. The variance of the bearing estimator for this process is derived and compared with computer simulation results for different integration times and input signal-to-noise (S/N) ratios. The simulation results illustrate how and why the bearing estimate degrades for very poor S/N ratios or very short integration times.
Reflection-Refraction of a Stress Wave at a Plane Boundary between Anisotropic Media
Authors: Henneke Edmund G.
Published: October 2005

A review is given of the pertinent equations necessary to describe the reflected and refracted waves at a plane boundary between anisotropic media and the utility of the wave surface in discussing this problem. The critical angle phenomenon in anisotropic media is discussed in terms of the energy flux vector associated with the reflected and refracted modes. The critical angle is shown to occur generally at that angle of incidence for which the energy flux vector of the reflected or refracted mode is parallel to the boundary and not when the wave vector is parallel to the boundary. The possibility of not needing a nonhomogeneous surface wave to satisfy the boundary conditions at angles of incidence greater than the critical angle is discussed for certain particular regions in some anisotropic materials.
Axisymmetric Vibrations of a Free Finite-Length Rod
Authors: Hutchinson James R.
Published: October 2005

The axisymmetric vibrational characteristics of an elastic circular rod of finite length with stress-free boundaries are analytically determined, and compared to approximate solutions. The solution approach consists of choosing a series of functions which term by term satisfy the governing equations and the boundary conditions on the shear stress. The boundary conditions on the axial and radial stress are satisfied by an orthogonalization procedure. This method yields an infinite eigenvalue matrix, the coefficients of which are transcendental functions of the frequency. It is found that the procedure converges and that sufficient accuracy is achieved, with truncation to a 20×20 eigenvalue matrix. Comparison is made of these results with the Pochhammer-Chree solutions which do not permit satisfaction of the boundary conditions on the ends of the rod. This comparison shows many similarities, but also some dissimilarities. Comparisons are also made with the lowest mode of the free-plate solution and the plane stress solution for very short rods, and with the one-dimensional rod solution for long rods.
Vibration Attenuation with Beams—Theory and Reciprocal Experiment
Authors: Snowdon J. C. , Kerlin R. L.
Published: October 2005

The theoretical prediction that significant regions of attenuation exist in the transmissibility curves of cantilever beams driven by dual forces of like magnitude and phase has been substantiated by the results of reciprocal experiments made on small aluminum beams and a laminated steel/viscoelastic beam. The attenuation provided by the laminated beam, which had high damping, was remarkably extensive and exceeded 15 dB at all frequencies above 100 Hz and 20 dB at all frequencies above 1.2 kHz. Agreement between theoretical prediction and reciprocal experiment has also been noted in two other cases: first, where the large region of attenuation predicted for a uniform cantilever beam was doubled in width and deepened by a factor of more than 10 when the beam was loaded by a suitably positioned lumped mass of similar magnitude to the beam mass (in fact, the resultant region of attenuation was bounded by frequencies that differed in value by a factor of 21 and was greater than 40 dB at its lowest point); and second, where a uniform cantilever beam was driven by forces that were not derived from an isolated source but, rather, were transmitted by two resilient mountings that supported a vibrating mass, which was used to represent a machine. Because the natural frequency of this simple mounting system fell well below the fundamental resonant frequency of the cantilever beam, the mounting system and the beam vibrated more or less independently. In consequence, the attenuation afforded by the simple mounting—essentially 12 dB/octave—superimposed on the region of attenuation noted previously in the beam transmissibility to provide an extremely large and continuous region of attenuation in the transmissibility across the combined simple mounting/beam system at all but low frequencies.
Multipath Summability in Ray-Theory Intensity Calculations in the Real Ocean
Authors: Neubert Jerome A.
Published: October 2005

By considering the stochastic nature of microfluctuations in the real ocean, the conventional ray-theory intensity relation is extended to permit consideration of partial coherence in multipath problems. The partial coherence factor is shown to be a function of the curvilinear range, the frequency, and the oceanographic conditions. In addition, a practical estimate for the standard deviation σI of the intensity about its expected value is found; σI is shown to depend on the partial coherence factor and to saturate as this factor approaches zero.
Acoustically Induced Gas Bubble Growth
Authors: Skinner L. A.
Published: October 2005

The diffusion problem governing gas bubble growth in oscillatory pressure fields, including growth through resonance size, is solved by superposition of two subproblems, one of which is the threshold problem discussed in an earlier paper. Approximate solution of the growth rate equation is shown to be independent of resonance behavior details.
Discrete Time Series Synthesis of Randomly Excited Structural System Response
Authors: Gersch Will , Luo Susan
Published: October 2005

A set of digital computer techniques for the generation of second-order stationary time series for the experimental—numerical study of problems involving the response of structural systems under random excitation is described. A discrete time system whose output covariance is identically that of the regularly sampled observations of a white-noise excited continuous time dynamical system is synthesized to accomplish that objective. The dynamical system is assumed to be an n-degree-of-freedom (df) system represented by a set of ordinary differential equations. An economical scheme for the computation of the covariance function of the continuous system is first indicated. The 4n parameters of a mixed autoregressive-moving average time series scheme whose covariance function is that of the given continuous system are computed. 2n autoregressive time series parameters are determined by solving an appropriate set of Yule-Walker equations. These coefficients and the original covariances imply a set of algebraic quadratic equations that can be solved recursively for the remaining 2n moving average parameters. An algorithm to verify that this discrete time system does indeed duplicate the continuous system covariance function is also indicated. This latter technique is a simpler way to compute the mean-square responses of white-noise excited scalar output systems than was previously known. Examples of the synthesis of 2- and 10-df systems as well as the synthesis of a rigid body transfer function approximation to a rocket are worked.
The Degree of Coherence of Acoustic Signals Scattered at Randomly Rough Surfaces
Authors: Novarini Jorge C. , Caruthers Jerald W.
Published: October 2005

A definition of degree of coherence of an acoustic wave scattered at a randomly rough surface is given as a special case of the standard form [M. Born and E. Wolf, Principles of Optics (Pergamon, London, 1959), p. 498]. This is accomplished by correlating the signal at a field point scattered by the rough surface and the signal that would be present if the surface were flat. This leads to an interpretation of coherence that is directly associated with the surface.
Temporary Threshold Shift in Hearing from Exposure to Different Noise Spectra at Equal dBA Level
Authors: Cohen Alexander , Anticaglia Joseph R. , Carpenter Paul L.
Published: October 2005

The intent of this study was to determine whether sound-level measurements in dBA could adequately depict harmfulness to hearing from exposures to noises differing widely in spectra. Each of 11 male listeners, ages 20–26 years, were exposed in separate sessions to each of three noises whose spectral slopes were −6, 0, and +6 dB per octave band and then re-exposed to the same test noises in three additional retest sessions. All such noises were presented for 30 min via an earphone at 100 dBA. Analyses of variance of the temporary threshold shifts in hearing caused by these noise conditions [corrected to 2 min postexposure (TTS2)] showed insignificant differences, owing to the spectral variations for both test and retest conditions as averaged across audiometric frequencies 250–8000 Hz. Interactive effects between spectra and test frequencies were significant, the −6- and 0-dB spectral conditions causing relatively more TTS2 at frequencies below 3000 Hz, and the +6-dB spectrum more TTS2 at frequencies above 3000 Hz. Implications of these results for noise hazard rating schemes using dBA measures as contrasted with spectral determinations were noted.
Mechanical Impact and Fatigue in Relation to Nonlinear Combination Tones in the Cochlea
Authors: Crane H. D.
Published: October 2005

In a previous paper the author tried to show that hypothesized mechanical impact and mechanical fatigue processes in the cochlea are consistent with a range of psychophysical data on auditory fatigue and non-linear effects (e.g., mechanical impact between the hair cells and tectorial membrane, and mechanical fatigue in terms of the viscoelastic or gel properties of the tectorial membrane). The present paper explores the extent to which mechanical processes of this type are also consistent with the recent findings of Goldstein [J. Acoust. Soc. Amer. 41, 676–689 (1967)] regarding combination tones in the cochlea. We develop the idea of a hair vibrating in a pocket within the tectorial membrane, which is formed by the local movement of the hair. It is assumed that this pocket tends to close around the hair with some specified time constant. It is shown that impact between a single hair and the ends of the pocket generates the main features of the combination tone sequence found by Goldstein. Other combination tones are also generated, though it is argued that these might be discriminated against in a completely distributed impact model. The most important feature of this impact and fatigue mechanism is a dynamic change in pocket size that provides the normalization factor that the data demands, since the relative strength of the combination tones is found experimentally to be independent of input level.
Auditory Thresholds of a Fresh Water Dolphin, Inia geoffrensis Blainville
Authors: Jacobs David W. , Hall John D.
Published: October 2005

A fresh water Amazon River dolphin, Inia geoffrensis, was conditioned to respond to pure tones by pushing a response lever. By using this method an audiogram was obtained for frequencies between 1.0 and 105 kHz. The animal was most sensitive to tones between 75 and 90 kHz. The sensitivity threshold in this area was −50 dB re 1 dyn/cm2. The effective upper limit of hearing was 105 kHz. No reliable response was elicited above 105 kHz using a random presentation and undistorted signal.
Mach Bands in Auditory Masking: An Attempted Replication
Authors: Rainbolt Harry , Small Arnold M.
Published: October 2005

This research attempts to replicate the report of Carterette, Friedman, and Lovell [J. Acoust. Soc. Amer. 45, 986–998 (1969)] who indicated the existence of auditory masking effects similar to Mach bands in vision. Threshold for sinusoids in narrow bands of noise were estimated for five listeners using an adaptive psychophysical procedure. The data show little, if any, similarity to Mach band effects, but rather are in line with what would be expected based on a traditional critical band concept.
Influence of Binaural Interaction on the Measurement of Perstimulatory Loudness Adaptation
Authors: Stokinger T. E. , Cooper W. A. , Meissner W. A.
Published: October 2005

Perstimulatory loudness adaptation was measured by two techniques which utilized varying amounts of simultaneous contralateral stimulation. In the first experiment a single-SDLB (simultaneous dichotic loudness balance) method was employed with comparison signals of 200- and 2000-msec duration and with an adapting signal of 8 sec. More adaptation was noted when the longer comparison signal was employed. In the second experiment, a modified tracking procedure utilized comparison signal duty cycles of 1623% and 50%. The higher duty cycle yielded a greater magnitude of test-ear adaptation than did the lower duty cycle. The results support the hypothesis that perstimulatory loudness adaptation is dependent on simultaneous binaural stimulation and, in addition, is related to the amount of that stimulation. It is therefore concluded that adaptation is not a monaural or a purely peripheral phenomenon.
Intensity, Frequency, and Duration Effects in the Measurement of Monaural Perstimulatory Loudness Adaptation
Authors: Stokinger T. E. , Cooper W. A. , Meissner W. A. , Jones K. O.
Published: October 2005

An experiment is described in which perstimulatory loudness adaptation is measured by delayed balance and by single simultaneous balance methods. The adapting signals consisted of all combinations of intensity (sound-pressure level 30, 50, 80, and 100 dB), frequency (250, 1000, and 4000 Hz), and duration (1, 2, 4, 8, 12, 16, and 30 sec). The results reveal little adaptation with simultaneous balances and slightly negative adaptation with delayed balances. Duration of the adapting signal had no significant effect on the data. However, the differences between methods of measurement, intensities, and frequencies of the adapting signal were statistically significant. All interactions, except those involving the duration factor, were statistically significant.
Detection of Binaural Tone Stimuli: Time Sharing or Criterion Change?
Authors: Treisman Michel
Published: October 2005

Moray [J. Acoust. Soc. Amer. 47, 660–661; 1071–1073 (1970)] has presented data on the detection of binaural tone increments which he interprets in terms of an attention-switching model. The data are re-examined and it is shown that they cannot easily be reconciled with this model. An alternative hypothesis is presented. This assumes that the input to the two ears is processed in parallel, and that different response criteria are applied to the detection of unilateral and bilateral signals. This account appears to give a more satisfactory and more parsimonious account of the data.
The Missing Fundamental and Periodicity Detection in Hearing
Authors: von Békésy Georg
Published: October 2005

This paper attempts to show that the traveling waves along the basilar membrane increase the relatively small amplitude of the first harmonic in Seebeck's experiment, so that the unexpected loudness of the first harmonic is of physical origin and does not contradict the place theory of hearing.
Comparison of Subglottal Air Pressures Associated with /p/ and /b/
Authors: McGlone Robert E. , Shipp Thomas
Published: October 2005

Subglottal air pressure measures obtained as subjects uttered VCV syllables containing /p/ and /b/ showed no significant differences between the two consonants. It was concluded that regardless of which stop was to be produced the respiratory system provided an undifferentiated driving force to be acted upon by the laryngeal and supralaryngeal structures.
Acoustical Society of America Policy on Noise Standards
Authors: Kryter Karl D.
Published: October 2005

The role of the Acoustical Society of America in connection with standards, particularly as related to noise, is reviewed in the light of the recommendations of the Ad Hoc Committee on Policy and Requirements of the Arden House Conference on Standards (July 1971).
Sound Transmission through a Double-Leaf Wall
Authors: Donato R. J.
Published: October 2005

The classical approach to the calculation of sound transmission loss through double-leaf walls is reformulated and various devices employed to reduce the resulting integrals to a tractable form for analytical solution. An approximation is made at low frequencies whereby, using a transform technique, the finite size of the wall may be included. Comparisons with experimental measurements show good agreement with theoretical predictions.
Electronic Design of a Test Device to Implement the Minimal Auditory Intensity Differential Stimulus
Authors: Boehm James A. , Dalton Leslie W.
Published: October 2005

This paper discusses the electrical specifications of the Minimal Auditory Intensity Differential Stimulus device and the electronic circuitry to implement these specifications.
Determination of the Expected Value of Array Gain for a Two-Dimensional Gaussian Random Array
Authors: Ho H. N.
Published: October 2005

The expected value of array gain for a two-dimensional Gaussian random array has been determined, assuming a two-dimensional isotropic noise field of single frequency. The results indicate that the expected value of array gain can be expressed as a function of the number of elements and the standard deviation of element spacing. For standard deviation of element spacings greater than unit wavelength, the expected array gain can be approximated quite accurately by a simple expression.
Vibratory Energy Converter
Authors: Russell Leslie T.
Published: October 2005

The description and operation of a “vibratory energy converter,” a device which permits the redirection of unwanted rearwardly directed vibratory energy to the front face of a transducer and insures that the wave arrives plane and in phase with the forwardly propagated energy, is presented. This device finds use in ultrasonics, sonar detection, and related fields.
Directivity of Jet Noise
Authors: Chu W. T. , Petersen R. A. , Kao K.
Published: October 2005

Ribner's proposed basic directivity of jet noise together with the modified Lighthill's convection effect have been used to predict the acoustic power of subsonic jets from a single point intensity measurement at 90° from the jet axis. The prediction was found to be very good from low subsonic to near sonic speeds for a 2-in.-diam model jet.
Propagation
Authors: Williams A. O.
Published: October 2005

These 20 years have seen much progress in understanding of underwater sound propagation. Few new topics have appeared, but far more complex problems can now be handled—in considerable part, thanks to computers. Emphasis has shifted to lower frequencies, longer ranges, and wave-theoretical methods. We are still limited by extreme variability of the medium and its boundaries, and by a gap of understanding between mechanical—chemical and acoustical properties. Efforts to narrow this gap should continue, as should the search for “invariants” of problems and for statistical theories to match averaged data.
Use of Side-Scanning Sonar for Contouring Bottom Features
Authors: Greischar L. L. , Clay C. S.
Published: October 2005

A side-looking sonar was used to study bottom features in Lake Mendota, Wisconsin. Interferences between direct and surface-reflected signals gave a tiger-striped pattern in the data. This pattern could be approximately interpreted as being the tracings of isoangle contours. However, this simple analysis was precluded by the strong gradients of sound-velocity profile. Ray traces were used to construct a profile of the interference field. The profile was used to interpret the data. Features having lateral dimensions of 10 m and a few meters depth were contoured. The data was taken when the sonar was about 100 m from the features.
Local Radiation Impedance of Vibrating Prolate Spheroids
Authors: Lauchle Gerald C.
Published: October 2005

Prolate spheroidal coordinates and associated prolate spheroidal wave functions have been used to study the sound radiation from arbitrarily vibrating prolate spheroids. A local radiation impedance is defined and discussed. This impedance shows the effect of the strong locally variable nearfield and indicates that the spheroid generates L/2R (L/2R = fineness ratio) more acoustic power per unit area at the equator than at the poles. The high-frequency asymptotic limit of the impedance is determined and from it a radiation criterion of higher modes determined.
Monostatic Scattering from the Ocean Bottom
Authors: Flowers K. D. , Hurdle B. G.
Published: October 2005

An experiment has been performed and the average monostatic scattering strength curve obtained. It is observed that the scattering strength curve for 39.0 kHz is essentially the same as that for 19.5 kHz for this experiment.
On the Fixed-Receiving-Point Problem in Channels with a Constant Sound-Speed Gradient
Authors: Warfield J. Thomas
Published: October 2005

In a channel in which the sound speed varies linearly with depth, the general determination of the initial ray angle for which a ray will intercept a fixed receiving point is inherently implicit, and an explicit expression is feasible only for certain source-receiver configurations. However, an explicit general solution has been obtained in other studies.
Interference Effect in a Multifrequency Ultrasonic Pulse Echo and Its Application to Flaw Characterization
Authors: Adler Laszlo , Whaley H. L.
Published: October 2005

The dependence of spectral variations within a reflected broad-band ultrasonic pulse on the size and orientation of the reflector was determined experimentally. An analytical model is developed on the assumption that interference of the waves received from the edges of the reflecting surface is responsible for the variations of the received frequency spectra. It explains the experimental results very well. The feasibility of determining the size and orientation of hidden flaws in metals by this method is demonstrated.
Diffraction of a Gaussian Light Beam by Ultrasonic Cylindrical Standing Waves
Authors: Hargrove L. E.
Published: October 2005

A theory is developed for the farfield diffraction of a Gaussian light beam that passes axially through an ultrasonic cylindrical standing wave. The approach is applicable only in the range of parameters for which the ultrasonic perturbation may be characterized as an axially symmetric phase grating. Although the diffraction integral is not completely integrated in terms of known functions, some useful expressions for the average and time-dependent light intensities are obtained. This acousto-optic interaction geometry, with the light-beam waist diameter equal to the first nodal diameter in the ultrasonic field, comprises an effective light modulator. Calculations of the on-axis time-dependent light intensity are presented and are confirmed by experimental results.
Formulation of Wave Equation for Calculating Velocity of Sound in Suspensions
Authors: Ahuja Avtar S.
Published: October 2005

A wave equation for the propagation of sound in suspensions or emulsions has been formulated from the simple considerations of mass and momentum balances on a sufficiently small homogeneous and compressible volume element of the suspension in the sound field. The induced masses of the non-neutrally buoyant oscillating particles and the adiabatic compressibilities of suspension components have been shown to modify the equations of continuity and momentum and thereby the wave equation, with respect to those equations for the single-phase suspending fluid. A formula for the velocity of sound in suspensions has been deduced, which agrees with that derived from the scattering theory.
Speech-Envelope Cues as an Acoustic Aid to Lipreading for Profoundly Deaf Children
Authors: Erber Norman P.
Published: October 2005

A speaker recorded lists of words on video tape. These lists were presented to normally hearing children and adults and to profoundly deaf children (average hearing threshold level greater than 95 dB ISO) for recognition through visual or combined acoustic-visual (A-V) modalities. For the normals, the acoustic stimulus was a 500-Hz octave-band noise amplitude-modulated by the envelope of the speech signal. For the profoundly deaf observers, the acoustic signal was either modulated noise or linearly amplified speech. Regardless of the type of acoustic signal they received, the mean A-V scores of the deaf children were 7% to 11% higher than their mean visual scores. The normals also demonstrated small mean improvements (6% to 8%) over visual reception when allowed both to watch the speaker's face and to listen to modulated noise. These results suggest that profoundly deaf children perceive mainly time-intensity (envelope) information when they are provided with an amplified speech signal.
Just Noticeable Differences for Segment Duration in Natural Speech
Authors: Huggins A. W. F.
Published: October 2005

A threshold-tracking method was used to measure both the incremental and the decremental just noticeable differences for segment duration in naturally spoken sentences. The measurements were made for a /p/ in five different contexts, including two that were word initial, two that were word medial, and one that was word final; for /∫,m/, and /l/ all in initial prestress position; and for a stressed vowel /ɔ/. The results show that subjects are much more sensitive to changes in vowel duration than to changes in consonant duration, and that changes in segment duration may have several different perceptual effects, including changes in perceived stress and perceived rhythm. When subjects based their judgments on changes in perceived stress or rhythm, they were usually able to detect smaller changes in duration than when they attended to other aspects of the stimuli.
On the Perception of Temporal Phenomena in Speech
Authors: Huggins A. W. F.
Published: October 2005

Experiments were performed to test whether a change made in the duration of one segment in a naturally produced sentence should be compensated in an adjacent segment if the sentence is to remain temporally fluent. The results showed that compensation is required between some pairs of segments, but not between other pairs, depending on where the two segments occur with respect to word and syllable boundaries. The results suggest that the perception of timing in natural speech is based on events at the syllabic level rather than at the segmental level, and that it is important to maintain the rhythm of the sentence, as defined by the onsets of vowels (especially stressed vowels), if the sentence is to sound temporally fluent.
Pressure Measurements of Articulatory Behavior during Alterations of Vocal Effort
Authors: Leeper Herbert A. , Noll J. Douglas
Published: October 2005

A direct-magnitude production scaling technique was employed to study the relationships of three speech variables: intraoral air pressure, lingual pressure, and sound pressure during changes in vocal effort. Selected CVC syllables containing two lingua-alveolar stop consonants /t/ and /d/ were produced at various effort levels and during periods of increased auditory masking. Exponents of the effort function for intraoral air pressure and for lingual pressure (1.7 and 1.8, respectively) suggest that speakers can monitor effort during speech production. Exponents for production of sound-pressure level (0.56) are similar to results of previous investigations. Systematically greater average values for /t/ contexts during both masked and nonmasked conditions distinguished intraoral pressure characteristics for consonants differing in force of articulation.
Effect of Interaural Switching on the Recognition of Speech Sounds
Authors: Rupf John A. , Hughes George W. , House Arthur S.
Published: October 2005

The intelligibility of nonsense syllables was investigated as a function of the place in the speech waveform where the signal was switched from one ear to the other. The results demonstrated that the place at which switching occurred had essentially no effect on the identification of either the consonants or the vowels in the stimuli. In view of these findings it is unlikely that phonological rules are applied before the signals to the two ears are combined in the auditory system.
Identification of Stops and Vowels for the Burst Portion of /p, t, k/ Isolated from Conversational Speech
Authors: Winitz Harris , Scheib M. E. , Reeds James A.
Published: October 2005

Stimulus segments (burst, and burst plus 100 msec of vowel) were isolated from words with initial and final /p,t,k/, and presented to listeners for identification. For the burst alone, initials were identified better than finals and /t/ showed the highest level of identification. Also, in many instances vowels could be identified on the burst portions, giving perceptual evidence for coarticulation. With the additional 100 msec, the level of identification, as was expected, was high. Providing phonotactic context, in some instances, raised this level of identification.
Hearing Thresholds from Toadfish, Opsanus tau, Measured in the Laboratory and Field
Authors: Fish James F. , Offutt George C.
Published: October 2005

Laboratory and field experiments are described in which toadfish hearing was investigated. The threshold to tonal stimuli determined in the laboratory using a conditional heart rate technique agreed closely with the field-determined threshold using an unconditional behavioral response. Below 150 Hz, the hearing threshold was about 100 dB re 1 μN/m2. Above 200 Hz, it increased rapidly at about 22 dB/oct. In addition to the tonal threshold experiments, a threshold to prerecorded playbacks of toadfish sounds was measured in the field. This threshold was about 15 dB higher than the tonal threshold in the same frequency range.
Information Analysis of Choice Behavior in Producing Acoustical Signals
Authors: Hupet Michel M.
Published: October 2005

Instead of presenting a perceptual stimulus to which a subject must assign numerical response, he is given a number from 1 to N and must then generate corresponding motor response. The amounts of information transmitted in producing acoustical signals varying in only one dimension, either their SPL (between 50 and 105 dB) or their frequency (between 50 and 6000 Hz), are compared to the amounts of transmitted information in identifying analogous signals.
Studies of Single Motor Units in the Speech Musculature: Methodology and Preliminary Findings
Authors: Sussman Harvey M. , Hanson Robert J. , MacNeilage Peter F.
Published: October 2005

Single motor unit muscle action potentials were recorded from various locations within the speech musculature using bipolar hooked-wire electrodes with 1 mm of separation between electrode tips. Initial attempts at characterization of the waveforms are described.
Precision Measurement of the Low-Frequency Velocity of Sound in Helium under Standard Conditions by a Resonance Tube Method
Authors: McIntyre Robert G. , Barnes Thomas G. , Chew Eddie W.
Published: October 2005

The velocity of sound in helium was measured to be 972.49±0.11 m/sec. The measurements were made using a resonance tube method at standard pressure and at 0°C. The tube, unique because of rigid plates at both ends, with acoustic coupling through small holes in one plate, is described. Corrections are made for the sound speed decrease caused by viscothermal absorption at the tube walls. A detailed description of the methods used in making the measurements is included, and the possible sources of errors are discussed.
Sound Field of a Pulsed, Planar, Straight-Edged Radiator
Authors: Freedman Albert
Published: October 2005

Assuming pulsed or CW conditions, theoretical expressions are derived for the farfield of an arbitrary plane straight-edged radiator, vibrating with spatially uniform velocity within an infinite plane rigid baffle. The results are then specialized to radiators whose shapes are regular polygons. The farfield is made up of components, termed “transmission replica pulses,” which are shown to act, in general, as if they originated at the corners of the radiators. Examples of pulsed field structure and of CW directivity curves of polygonal radiators are presented.
Ray Theory for an Inhomogeneous Moving Medium
Authors: Thompson Robert J.
Published: October 2005

Starting from the fundamental equations of hydrodynamics, the theory of sound rays in an inhomogeneous moving medium is developed. A system of first-order ordinary differential equations which determine the ray paths is derived. It is shown that the ray paths can be found by evaluating some definite integrals. The integrals may be evaluated numerically, but in some important cases the integrations can be done in closed form. Much of the emphasis in the paper is on deriving properties which are useful in computing ray paths or in understanding the qualitative effects of inhomogeneities in the medium. It is shown, for example, how rays which are ducted can be distinguished from those which are not. Finally, it is noted that the literature contains what amounts to two conflicting theories for sound rays in a moving medium. The differences are discussed, and it is pointed out that one of the theories is inconsistent.
Theory of Vibration of Initially Stressed Shells
Authors: Kalnins Arturs , Biricikoglu V.
Published: October 2005

Governing equations are derived for an initially stressed shell undergoing an infinitesimal elastic process in which transverse shear and normal strains are accounted for. The point of view is adopted that this process begins with the initially stressed state for which geometry, state of stress, and material properties are known. The equations represent an exact two-dimensional counterpart of the corresponding equations for an initially stressed three-dimensional medium. The only approximation introduced is that of a linear displacement field in the transverse direction. The equations contain all initial stress terms, and they can be applied to determine the effect of the initial stresses in all types of modes of free vibration of a shell.
Sound Transmission in an Isospeed Ocean Channel with Depth-Dependent Current
Authors: Stallworth L. A. , Jacobson M. J.
Published: October 2005

A constant sound-speed (isospeed) channel with horizontal boundaries and a current of constant direction and linear depth-dependent magnitude is considered. Ray paths are shown to be closely approximated by connected circular helical arcs. Expressions for the travel time and spreading loss of individual arrivals are found when necessary and sufficient conditions for the ray paths to be plane curves are satisfied. For a bottom-mounted source and receiver, it is shown that a current gradient can significantly affect the ray geometry, travel time, and spreading loss of each arrival. The total field for a 33-km × 40-m channel is calculated. It is found that small changes in the current gradient can produce large variations in the amplitude and phase of the field including the amplitude fade-phase offset phenomenon.
Comments on “Approach to the Multiple-Surface-Reflection Problem in a Linear-Gradient Medium” [D. T. Raphael, J. Acoust. Soc. Amer. 49, 1680–1681(L) (1971)]
Authors: Stallworth L. A.
Published: October 2005

The response by D. T. Raphael [J. Acoust. Soc. Amer. 49, 1680–1681 (L) (1971)] to a letter by M. J. Jacobson [J. Acoust. Soc. Amer. 49, 1679–1680 (L) (1971)] claims that the examples cited by Jacobson contain no explicit, closed-form solutions for the initial inclination angle of a ray that intersects a receiving point. One such solution is shown to exist in the cited examples.
The “Noise Thermometer”: A Large-Display Sound-Level Meter
Authors: Brammer A. J. , Toole F. E.
Published: October 2005

A large-display sound-level meter has been constructed as an experiment in public education. The indicator is an array of lights so arranged that the sound level produced by a source is displayed as an illuminated column. In a roadside installation, motorists see a thermometer-like display ahead and can compare the level produced by their own vehicles with the maximum level permitted by legislation, as shown by vehicle silhouettes. The device registers from 70–100 dBA in 2-dBA steps with an accuracy approximately equal to one increment of the scale.
Some Problems of Active Sonar Signal Design
Authors: Hill F. S. , Schultheiss P. M.
Published: October 2005

The paper deals with the problem of active sonar signal design for best range-estimation accuracy at a time not necessarily coincident with the instant of measurement. Thus, velocity as well as range information, is important. For a single sonar ping a matrix of second-order statistics of range and velocity errors is obtained for the case of ambient and/or reverberation noise interference. These error statistics are related to a generalized signal-to-noise ratio, and simple expressions are obtained for their relative magnitudes. For a particular type of linear FM signal it is shown that these relative magnitudes are independent of target or scatterer motion and of the relative importance of reverberation and ambient noise. The results are extended to the case of several sonar pings separated in time, and simple expressions are obtained for the over-all error statistics. If two pings are to be used, it is shown that in many cases the first ping should be designed simply to measure target velocity, while the design of the second ping should make use of this velocity measurement and strive at an accurate measurement of range.
Integration Time Variance in Reverberant Room Measurements
Authors: Ingalls D. J.
Published: October 2005

The normalized variance due to the finite integration time of instrumentation used for determining the space-time average of the sound-pressure level in a reverberant room is given by 19/BTI, in (dB)2, where B is the bandwidth of noise and TI the integration time of instrumentation. This result is smaller by a factor of 2 than an earlier result reported by Andres [Acustica 16, 271–294 (1965). Transl.: Bolt, Beranek and Newman, TIR-10 (1968)]. This factor may account for the difference between the result found by Andres and the results reported by Kurtovic [Ann. Telecommun. 16, 254–261 (1961)], Schroeder [J. Acoust. Soc. Amer. 46, 277–283 (1969)], and Lubman [J. Acoust. Soc. Amer. 44, 1491–1502 (1968)] for the normalized variance of the sound-pressure level.
Direct Estimation of Multidimensional Tonal Dissimilarity
Authors: Carvellas Thomas , Schneider Bruce
Published: October 2005

Magnitude estimates were obtained for the dissimilarity of pure tones varying in frequency and intensity. In Expt. 1, a spatial embedding for a set of seven tones was determined by assuming the magnitude estimates represented distances in a two-dimensional space whose coordinate axes were pitch and loudness. Embeddings were determined for both Euclidean and “city-block” distance functions. A linear relation was consistently observed between the projections of the tones on dimensions of pitch and loudness and their values on Stevens's mel and sone scales, with the city-block projections usually yielding higher correlations. In Expt. 2, 11 tones were used and the magnitude estimates of dissimilarity were compared to the tightly constrained “monotone” distances derived from the rank-order properties of the dissimilarities. The agreement observed between the magnitude estimates and the monotone predicted distances strongly supports a distance interpretation for the dissimilarities.
Auditory Distortion Products f2−f1 and 2f1−f2
Authors: Hall J. L.
Published: October 2005

Two primary tones of frequency f1 = 368–1475 Hz and f2 = 1.1–1.5 times f1 were presented monaurally at 60–80 dB sound-pressure level. Nonlinear distortion products at both f2−f1 and 2f1−f2 were made to beat against low-intensity probe tones slightly mistuned from the frequency of the distortion product. Subjects adjusted the amplitude and phase of cancellation tones at the frequency of the distortion product to eliminate the beating. The amplitude and phase of the 2f1−f2 cancellation tone agree with results already in the literature. The amplitude of the f2−f1 cancellation tone relative to the primary tones is insensitive to amplitude of the primary tones. Both the amplitude and phase angle of the f2−f1 cancellation tone decrease with an increase of f1 or f2/f1. Differences between properties of the 2f1−f2 and f2−f1 cancellation tones are consistent with a model for generation of distortion products proposed by Goldstein.
Exploratory Studies of Zwicker's “Negative Afterimage” in Hearing
Authors: Lummis Robert C. , Guttman Newman
Published: October 2005

This paper describes several exploratory experiments on a subjective tone that Zwicker discovered and referred to as the “negative afterimage.” Zwicker described the tone as audible upon cessation of a band-rejected noise or band-rejected pulse train stimulus, and as having a pitch corresponding to a frequency within the rejected band. We worked exclusively with noise stimuli. Our principal finding is that the minimum adequate stimulus appears to be a spectral edge rather than a rejected band, and that a low-pass edge is more effective than a high-pass edge. Other findings are as follows. Most people hear the tone, but susceptibility varies widely and the effect is labile. With favorable stimulus parameters, precision of matching to its pitch is on the order of 5% to 10% of the mean. The principal determinant of pitch is the location of the edge of the low-pass component of the stimulus; the pitch corresponds to a frequency about 23 oct above that edge. Energy in the high-pass component of the inducing stimulus enhances perception of the tone but has little effect on its pitch.
Signal Detection as a Function of Contralateral Sinusoid-to-Noise Ratio
Authors: Yost William A. , Penner M. J. , Feth L. L.
Published: October 2005

Detection of a masked signal (500 Hz) at one ear was measured while a sinusoid of the same frequency and a noise were presented to the contralateral ear. Both the signal and the contralateral sinusoids were pulsed, and they were either in phase or inverted. The noise at the signal ear was presented continuously at a spectrum level of 40 dB. In Expt. 1, the same continuous noise was presented to the contralateral ear at a spectrum level of 40 dB and in phase with the noise in the signal ear. The contralateral sinusoid-to-noise ratio was varied by changing the level of the sinusoid. In Expt. 2, the contralateral sinusoid-to-noise ratio was held constant while the levels of both the contralateral sinusoid and the contralateral noise were varied. When the contralateral sinusoid and noise are intense, a 50-dB increase in the contralateral sinusoid-to-noise ratio causes a 25- to 35-dB change in the signal-to-noise ratio required for detection. The results show that contralateral stimulation can either enhance or degrade detection of a monaural signal. The results are compared to data from investigations of masking-level difference, central masking, and monarual detection with contralateral cue.
Bilabial Closure Durations for /p/, /b/, and /m/ in Voiced and Whispered Vowel Environments
Authors: Schwartz Martin F.
Published: October 2005

A study was made of the duration of bilabial closures for /p/, /b/, and /m/ under voiced and whispered speaking conditions. The results, obtained from 12 normal-speaking young adult males, indicated significantly greater whisper durations for /p/ and /b/ but not /m/. An explanation for this finding is offered in terms of the hypothesis that individuals conserve air when whispering by prolonging air-arresting articulatory gestures.
Measurements of Ultrasonic Velocities Using a Digital Averaging Technique
Authors: Lacy Lewis L. , Daniel A. C.
Published: October 2005

A new pulse-echo technique using real-time digital averaging is described for measuring the phase velocity in solids up to 50 MHz. The technique can measure the transit time between any two echoes to an absolute accuracy of 0.1 nsec and measure small changes in transit time to a sensitivity of 20 psec. Experimental examples are given based upon ultrasonic velocity measurements in a single crystal superconductor.
Multipole Expansion of Sound Radiation from Moving Rigid Bodies
Authors: Eisler Thomas J.
Published: October 2005

The solution of the wave equation with a source term extended in space and moving as a rigid body with translation and rotation is expanded about an interior point in terms of point multipoles, which are expressed as spatial derivatives of the Liénard-Wiechert solution for a monopole. An application to sound radiation from moving rigid bodies is given using the theory of Ffowcs-Williams and Hawkings. As examples, the radiation fields of a rotating ellipsoid and a sphere in accelerated rectilinear motion are estimated.
Transmission of Sound in Ducts with Thin Shear Layers—Convergence to the Uniform Flow Case
Authors: Eversman Walter , Beckemeyer Roy J.
Published: October 2005

The problem of the transmission of sound in a duct with very thin shear layers at the walls is treated by an inner expansion method. The results show that the formulation of the problem of the transmission of sound in a duct with a shear layer at the wall converges, in the case of a vanishingly thin shear layer, to the formulation of the same problem when uniform flow is assumed and the wall boundary condition is that of continuity of particle displacement.
Vibrations of Circular Elastic Plates due to Sonic Boom
Authors: Pavagadhi L. J. , Yajnik M. D.
Published: October 2005

The problem of transient axisymmetric vibrations of thin circular elastic plates due to sonic boom excitation is investigated. The equation of motion for a solid circular plate is solved by applying the modified finite Hankel transform and the Laplace transform, and the numerical results are obtained with the help of the digital computer. From the analysis of the data, obtained for the dynamic deflections of the plates for the boom duration, it is concluded that for a normal flight the boom duration has a significant effect on the vibrations of plates as compared to the overpressure of the boom.