bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlation techniques applied to acoustical measurements in reverberant rooms
Authors: Schomer P. D.
Published: October 2005

Feasibility of performing transmission loss and diffraction measurements using correlation techniques has been demonstrated in an earlier work. In the present paper, these methods are extended from a simplified anechoic environment to a more complicated reverberant environment. The reverberant environment is considered to be the worst condition under which measurements can be made, and thus a true test of the method. Various difficulties are encountered in translation of this method to a reverberant environment and these difficulties are discussed and their solutions indicated. Results suggest that the correlation technique will be a viable measurement method.
Neural coding and psychophysical discrimination data
Authors: Luce R. Duncan , Green David M.
Published: October 2005

Data from first-order auditory fibers are modeled as a simple renewal process. The interarrival times of neural spikes are treated as a geometric process at multiples of the period of the input signal modified by some temporal jitter, characterized as a frequency-dependent random variable with a standard deviation proportional to a small fraction of the period of the waveform. Two classes of models are considered: a timing model in which psychophysical decisions are based on the time taken to obtain a predetermined number of counts on many parallel channels, and a counting model in which psychophysical decisions are based on the number of neural events that occur within some fixed time on many parallel channels. For both models it is assumed that the geometric parameter is monotonically a power function of signal intensity, that the threshold criterion of activity in a channel is independent of frequency, and that the number of channels is independent of both signal intensity and frequency. Predictions concerning the discrimination of change in frequency and intensity of a sinusoid are derived. Existing data, both for intensity and frequency, are sufficiently consistent to reject the timing model (which one would expect from other considerations), but they are not sufficiently consistent to provide either a strong test of the counting model or sharp estimates of the parameters of the model.
Hearing loss due to continuous exposure to steady-state broad-band noise
Authors: Passchier-Vermeer W.
Published: October 2005

An analysis is made of data from a number of field investigations concerning the influence of steady-state broad-band noise on the hearing of workers, exposed to it continuously for eight hours a day. The results relate to exposure times ranging from 10 to 40 years and to noise with noise-rating numbers for 500 to 2000 Hz (NR) ranging from 75 to 98 or sound levels from 80 to 103 dBA. Noise-induced shifts of the median hearing levels as well as shifts indicated at the 90th, 75th, 25th, and 10th percentiles, were determined for seven frequencies between 500 and 8000 Hz as a function of exposure years and sound level. The variability in hearing levels associated with noise exposure was shown to be constant after ten exposure years and an increasing function of sound level at each frequency except 4000 Hz. At this frequency, the variance in hearing levels decreased with increasing sound level. The limit of permissible noise exposure, defined as the maximal level which did not cause measurable noise-induced shift in hearing levels of workers exposed to it irrespective of exposure years, was shown to be NR 75 or 80 dBA. An acknowledgment is made of the need for hearing-conservation measures given exposure conditions which exceed 80 dBA.
Simulation of the effect of recruitment on loudness relationships in speech
Authors: Villchur Edgar
Published: October 2005

Persons suffering from perceptive deafness commonly find it difficult to understand amplified speech, and their understanding of speech is easily destroyed by competing speech or noise. One source of perceptive distortion is recruitment, which exaggerates loudness differences among the acoustical elements of speech. A transposition of these distorted loudness relationships from the deaf-subject span of hearing to the normal span is illustrated graphically, and achieved in practice with an electronic processor. A recording of processed speech, simulating for normal listeners the loudness relationships perceived by deaf subjects with recruitment, accompanies this paper. Recruitment-compensation processing for hearing aids is also simulated. The recruitment simulation is validated by an experiment with four unilaterally deaf subjects, who compared processed speech in the normal ear with unprocessed speech in the impaired ear. The simulation suggests that (1) recruitment is a sufficient cause for loss of intelligibility in the deaf, whether or not there are other causes; (2) compensation for this recruitment is a necessary, although possibly insufficient, condition for restoring that intelligibility; (3) the benefit of using both compression and post-compression equalization in a hearing aid designed to compensate recruitment is likely to be considerably greater than the arithmetic sum of the separate, limited benefits of each process; and (4) the combined processing, by restoring redundant speech-recognition cues to the subjects's perception, can increase the resistance of intelligibility to acoustical interference.
Auditory feedback in the regulation of voice
Authors: Siegel Gerald M. , Pick Herbert L.
Published: October 2005

Adult speakers participated in a spontaneous speech task in which the intensity of their auditory feedback through earphones was systematically manipulated over a 20-dB-SPL range. In Experiment I, Ss showed a statistically significant but slight tendency to decrease their vocal intensity as sidetone was amplified. The effect was greatest when subjects were instructed to attend to their sidetone and to compensate for any changes in loudness. In Experiment II, the same procedures were repeated except that 80-dB-SPL noise was added in the earphones. Addition of the noise resulted in considerably enhanced sidetone-amplification effects, even when Ss were instructed to keep their vocal level constant. In Experiment III, several levels of noise (0, 60, 70, 80 dB SPL) were used and it was noted that the greater the noise, the more substantial were the sidetone-amplification effects. In Experiment IV, subjects were instructed to talk either louder or softer than usual, with and without noise. The data from this last experiment indicate that it is the presence of the noise that enhances response to sidetone manipulations, and not simply the level at which the subjects are talking.
Determination of the instant of glottal closure from the speech wave
Authors: Strube Hans Werner
Published: October 2005

For vowels excited by vigorous glottal vibrations, the instant of glottal closure is tentatively identified with the moment of strongest excitation (at not too low frequencies) and worst linear predictability. Some predictor methods for its determination are reviewed, which do not always yield reliable and unequivocal results. Then Sobakin's method using the determinant of the autocovariance matrix is examined critically and reinterpreted such that the determinant is maximum if the beginning of the interval on which the autocovariance matrix is calculated coincides with the glottal closure. This hypothesis is tested by comparison with the predictor methods and by looking at the inversely filtered waveforms and the formants obtained from predictors determined on a shifted interval. The determinant method seems to be very reliable even for otherwise difficult cases, such as the vowel /u/.
Attenuation and reflection of ultrasound in canine lung tissue
Authors: Bauld T. J. , Schwan H. P.
Published: October 2005

Canine lung tissue was investigated with short pulses of ultrasonic energy at frequencies of 2.4, 5.0, and 7.4 MHz. The objective was to determine the basic ultrasonic parameters of the tissue in the frequency range of present clinical ultrasonic apparatus and to assess the possibilities of using ultrasound as an aid in the diagnosis of diseases of the lung. Attenuation coefficients and reflection losses were measured for samples of fixed inflated tissue and collapsed freshly excised tissue. The reflection loss depended strongly on the degree of inflation and, unlike the results for other soft tissues, the reflection loss varied with the frequency. The attenuation coefficients increased linearly with frequency and were an order of magnitude greater than the values for other tissues. The fixation process did not substantially change the ultrasonic parameters. Because of the very high attenuation coefficients, the usefulness of ultrasound in diagnosis may be limited to conditions which are manifested at or near the periphery of the lung. The large variation of the reflection loss with frequency is felt to be potentially very important, although further experiments using samples with specific disorders are required to determine the sensitivity of the reflection loss to changes in the condition of the tissue.
Release of serotonin from human platelets by acoustic microstreaming
Authors: Williams A. R.
Published: October 2005

Fresh human platelet-rich plasma was prepared from adult blood anticoagulated with EDTA, and the platelets allowed to incorporate tritiated serotonin. Samples were sheared for 5 min at 23°C by the acoustic microstreaming field generated around submerged portions of a transversely oscillating steel wire (115-μm radius driven at 20 kHz). Immediately following irradiation, each sample was centrifuged for 5 min to sediment intact cells and debris, and the quantity of serotonin released into the supernatant was measured using a liquid scintillation counter. There was no measurable threshold below which serotonin was not liberated, after allowances had been made for the spontaneous release of serotonin. In addition, it was found that the amount of serotonin released by irradiation alone varied with the square of the wire-displacement amplitude, indicating that hydrodynamic shear stress and velocity gradient are probably the agents responsible for the release of serotonin (together with the simultaneous release of clot promoting and/or accelerating factors).
Vibrator sensors for atmospheric pressure, temperature, and humidity measurements
Authors: Kagawa Yukio
Published: October 2005

Circular vibrator sensors for atomospheric pressure, temperature, and humidity measurements by means of the natural frequency change have been developed. Uniform pressure over a circular plate supported at the edge causes an axisymmetric deformation to a quasi-shallow spherical cap, which changes the natural frequency of the plate. A similar deformation effect is achieved with temperature or humidity by employing bimaterial construction for the plate. Change of the natural frequency is linear with the atmospheric pressure, temperature, or humidity over a relatively wide range, and the sensitivity is sufficiently high for practical applications. The devices are suitable for telemetering and digital measurement applications.
Primary auditory stream segregation of repeated consonant—vowel sequences
Authors: Lackner James R. , Goldstein Louis M.
Published: October 2005

Determination of the relative order of a sequence of alternated V and CV syllables is prevented by the perceptual splitting of the sequence into two distinct perceptual groupings such that vowels are heard in one spatial locus and the consonants in another. This “splitting” occurs for both monaural and binaural presentations.
Propagation of radiation from a finite beam or source through an anisotropic random medium
Authors: Beran M. J. , McCoy J. J.
Published: October 2005

In a previous paper, we solved the problem of propagation of a plane wave in an anisotropic random medium. The characteristic correlation distances in the horizontal propagation direction were assumed to be large compared to the radiation wavelength divided by 2π, (λ̄/2π), while in the vertical direction, these distances were, roughly speaking, assumed to be of the same order or smaller than λ̄/2π. For this medium, we derive here the equation governing the propagation of the coherence function for a finite beam or source of characteristic dimension a. This equation is then averaged over the vertical direction and solved. The solution is given in terms of a definite integral over the horizontal spectrum of the index-of-refraction field. The point source solution (a → 0) and the plane-wave case (a → ∞) are given as special cases. Explicit solutions are given for the propagation of an acoustic field in the ocean under conditions for which the spectrum satisfies a minus two power law.
Scattering of sound from time-varying irregular free surfaces
Authors: Konrady J. A.
Published: October 2005

The problem of sound scattering from a time-varying irregular free surface is treated anew. The wave equation with its complicated surface boundary condition is transformed to another partial differential equation with a simple, perfectly reflecting, boundary condition. An integral equation for the Green's function G′ of this latter equation is found which admits a Neumann series solution. The Green's function G for the original wave equation is determined from G′ via a simple transformation. The Green's function G is explicitly calculated to second order in the surface wave height. A plane-wave scattering formalism is developed in which scattered-wave amplitudes are expressed in terms of G′. The differential cross section for surface scattering is expressed in terms of the scattered-wave amplitudes and is explicitly calculated to second order in the wave height and expressed in terms of the space-time covariance of the irregular surface. With suitable additional approximations, the autocovariance and power spectrum are computed to second order for an acoustic signal generated from a fixed sinusoidal source. The results are expressed in terms of previously derived plane-wave quantities, the differential cross section, and forwardscattering amplitude. The perturbation calculations are valid provided the rms wave height is small compared to the principal wavelength of sound used.
Multiple scattering of waves by a uniform random distribution of discrete isotropic scatterers
Authors: Lin James C. , Ishimaru Akira
Published: October 2005

Integral equations describing the multiple-scattering effects of waves propagating in a discrete random medium are solved using Fourier transform techniques. The average intensity in the medium for a given source radiation is expressed in terms of a Green's function which consists of residue contribution at a pole representing diffusion and a branch cut integration pertaining to nearfield. It is shown that for a plane wave, multiple scattering becomes significant when the particles are mostly scattering (albedo, b > 0.5) for all distances greater than a fraction of an optical depth Z. When the particles are mostly absorbing, multiple scattering will not take effect until at least Z > 2. For a spherical wave, the multiple-scattering influence does not become significant until several optical depths, except when the scatterers are extremely low loss (b → 1).
Three-dimensional acoustic streaming near a stagnation point
Authors: Wang Chang-Yi
Published: October 2005

The general three-dimensional high-frequency oscillatory flow near a stagnation point is investigated through the method of matched asymptotic expansions. The nonlinear Reynolds's stresses create a steady streaming motion in the fluid. It is found that this streaming is minimized when the surface near the stagnation point is axisymmetric and is maximized when the surface is a saddle.
Low-frequency acoustic scattering from a trailing vortex
Authors: Ferziger Joel H.
Published: October 2005

The cross section for the scattering of low-frequency (∼ 100 Hz) sound by an aircraft trailing vortex is computed using the Born approximation. The predicted cross section is large enough to permit size and strength measurements. Although precise location of a vortex is better done with high-frequency refraction, a monitoring system based on low-frequency acoustic radar is possible, and a system combining the best features of each is also feasible.
Application of the USRD type E8 transducer as an acoustic parametric source
Authors: Eller Anthony I.
Published: October 2005

The USRD type E8 transducer was operated as an acoustic parametric source, and its performance as such was measured in two separate laboratory experiments and at sea. The parametric source was driven by a primary signal that consisted either of two high-frequency components or of an amplitude-modulated high-frequency carrier. The primary signal was centered at the transducer resonance frequency near 1.4 MHz, and the observed difference frequencies ranged from 20 to 200 kHz. During typical operation the primary electrical signal had a total power of approximately 6 W, and a difference-frequency signal at 50 kHz had a source level of about 154 dB re 1 μPa m. This paper describes the design and performance of the parametric source. It also presents a sequence of radiation patterns and values of beamwidth that illustrate difference-frequency beam formation in the nearfield of the parametric source.
Modified ray theory for bounded media
Authors: Murphy E. L. , Davis J. A.
Published: October 2005

In earlier investigations, “modified ray theory” has been developed using a generalized version of the WKB or geometrical-optics approximation based on Weber functions for solutions of the scalar wave equation for the “two-turning-point” unbounded sound-propagation problem. This wavelength-dependent theory provides a ray representation in reflection and transmission regions for some of the diffraction phenomena that arise in a stratified medium. In the present paper, both Airy and Weber functions are used as a basis for the generalized WKB procedure to carry out analysis for various classes of sound-speed profiles, and the development of modified ray theory is extended to include the effect of boundaries of a type pertinent for underwater sound propagation.
Free and forced vibrations of rods according to Bishop's theory
Authors: Rao D. K. , Rao J. S.
Published: October 2005

The equations of motion of longitudinal vibrations of rods according to the theory of Bishop are rederived using Hamilton's principle, in the process of which the associated boundary conditions are also obtained. The frequency equations and mode shapes for ten different combinations of boundary conditions are given. The influence of the secondary effects an the fundamental frequency of rods is illustrated and it is shown that the effect of lateral inertia is almost three times as important as the effect of shear stiffness. Studies of free and forced vibrations of rods by the eigenfunction expansion process show that the higher-order theory predicts a maximum response which is less than the one predicted by the elementary theory of rods. Comparison with the available experimental data show that the Bishop theory represents a better model for predicting the response of a free-free rod subjected to a suddenly applied force.
Estimation of error in motor-vehicle noise-level measurements
Authors: Hemdal John F.
Published: October 2005

In several SAE standards for the measurement of noise levels of motor vehicles, the allowance for measurement error is given as 2 dBA. A number of investigators, however, found the variations of certain influencing factors to be larger than 2 dBA. These investigators then use these results to suggest that the overall measurement would exhibit errors of the same magnitude as the variation in the influencing factors. However, as this note shows, the measurement of sound-pressure levels according to the SAE procedure has a lower variance than that of the distribution of instantaneous sound-pressure levels.
Rate versus level functions for auditory-nerve fibers in cats: tone-burst stimuli
Authors: Sachs Murray B. , Abbas Paul J.
Published: October 2005

Average discharge rate of single auditory-nerve fibers in cats was measured in response to 400-msec tone bursts. For each fiber, rate versus stimulus-level functions were constructed for a number of frequencies. For tones at a fiber's characteristic frequency (CF), rate increases rapidly over a range of 20 to 30 dB above threshold. For higher stimulus levels, a range of behaviors is observed. For some fibers, rate saturates completely at higher levels; i.e., there are no further systematic increases in rate when level is increased beyond about 30 dB above threshold. For other units there is a noticeable bend in the rate-level function at 20 to 30 dB above threshold; however, rate can continue to increase gradually over another 30 to 40 dB. For frequencies above fiber CF, the slope of rate-level functions measured near the midpoint between maximum and spontaneous rates is a decreasing function of frequency. For frequencies below CF, slope is either approximately constant and equal to the slope at CF or increases to some maximum value as frequency is decreased from the CF. These properties of rate-level functions are well accounted for by a simple model consisting of a mechanical stage followed by a saturating nonlinearity (transducer stage). The input (pressure) versus output (basilar membrane displacement} functions for the mechanical stage are taken directly from the measurements of Rhode. The input-output function for the transducer is developed empirically.
Transformation of sound pressure level from the free field to the eardrum in the horizontal plane
Authors: Shaw E. A. G.
Published: October 2005

Measurements of pressure transformation, azimuthal dependence, interaural level difference, and ear canal pressure distribution from 12 studies are brought together in a common framework. The pool of data covers 100 subjects, the majority male, measured in five countries over a 40-yr period. Logical procedures are developed to identify the surfaces which best fit these essentially three-dimensional distributions of data, making allowance for the many disparities between studies. Sheets of data are presented showing transformation to the eardrum, azimuthal dependence, and interaural difference as functions of frequency from 0.2 to 12 kHz at 45° intervals in azimuth. Other sheets show azimuthal dependence and interaural difference as functions of azimuth at 24 discrete frequencies. The logical procedures, data presentations, and review of disparities lead to the construction of self-consistent families of curves best fitting the data and showing the average sound pressure transformation from the free field to the human eardrum as a function of frequency at 15° intervals in azimuth. Possible explanations of differences between studies are suggested.
Directional hearing of a harbor seal in air and water
Authors: Terhune J. M.
Published: October 2005

Minimum audible angles (MAA) of a harbor seal were determined using a click-train stimulus (left-right, forced choice) and found to be 9°±4° underwater and 3°±4° in air. After accounting for the sound-speed differences, the MAAs and the similarities of the psychometric functions suggest that interaural time differences provide the most important clue. The findings indicate that the interaural distance is the same in both media. An implication of this is that nonbony tissues are not sound transparent in water. MAAs in air were determined using other signal types. Click trains and 1/3-octave noise sources above 3 kHz were localized with greater acuity than sinusoidal or low-frequency noise stimuli. The findings indicate that signals containing well-defined time clues are localized more readily than signals containing only intensity and/or phase information.
Comments on “Acoustic backscattering from a rough surface at extremely low grazing angles” [R. R. Gardner, J. Acoust. Soc. Am. 53, 848-857 (1973)]
Authors: Hall Marshall
Published: October 2005

A paper by Gardner on acoustic backscattering from a rough sea surface at grazing angles between 1° and 10° is critically analyzed. Gardner's theoretical development appears to indicate that the backscattering strengths at these angles are between −40 and −30 dB, whereas another theory shows that they should be less then −70 dB. This anomaly occurs because Gardner applies the Kirchhoff approximation (modified by a shadowing function) to a surface which has discontinuous slopes. Gardner's theory also predicts that the backscattering strengths increase as the grazing angle decreases. This effect is due to an unjustified division of the scattering strength by the sine of the grazing angle. The relevance of Gardner's experimental work to the theory is not conclusive. The measured reverberation is compatible with backscattering from the sea floor.
Comments on “Finite element analysis of acoustically radiating structures with applications to sonar transducers” [R. R. Smith, J. T. Hunt, and D. Barach, J. Acoust. Soc. Am. 54, 1277–1288 (1973)]
Authors: Knittel Max R. , Nichols Charles S. , Smith Robert R. , Barach Don
Published: October 2005

Transmitting voltage responses are calculated for several free-flooded cylinder transducers. It is shown that redesigning a cylinder to have breathing and bending resonances that are close in frequency does not create a flat response over a much wider frequency band. A significant improvement can be made, but maxima and minima in the response that are associated with cavity resonances cannot be eliminated without degrading the reponse at other frequencies.
Determination of the transfer function of the external ear by an impulse response measurement
Authors: Mellert V. , Siebrasse K. F. , Mehrgardt S.
Published: October 2005

The transfer function of the human ear in a free sound field is measured by an impulse response technique. The impulse response of the system is determined and the frequency response is computed with aid of a digital computer. Disturbing responses in time and frequency domain caused by loudspeaker, probe microphone, and surrounding objects are eliminated.
Further observations of intraoral pressures during sentence production
Authors: Brown W. S. , McGlone Robert E.
Published: October 2005

The purpose of this study was to obtain further information related to the changes that occur in intraoral pressures (tongue and air) as a result of increased vocal intensity caused by masking auditory feedback. Four males repeated sentences containing the /t,d,n/ consonants, during which different levels of masking were introduced binaurally. No significant differences in either intraoral pressure as a function of change in the masker level were noted. Furthermore, no systematic differences between /t/, /d/, and /n/ were observed for tongue pressures. These results are contradictory to previous studies; the contradictions were related (but not totally) to the speech samples used (the present study incorporated sentence materials whereas previous studies used nonsense syllables). Left-right dominance associated with tongue pressure was also noted.
Evidence for a theory of speech production based on observations of the speech of children
Authors: DiSimoni Frank G.
Published: October 2005

Studies of phoneme duration are reviewed for the purpose of explaining possible mechanisms to account for observed differential durational effects. Information relative to the chronologic appearance of these mechanisms in children is presented showing a developmental sequence and suggesting the possible interrelationship of mechanisms. Findings are related to the model of speech production proposed by MacNeilage and DeClerk.
An economic acoustic holography system
Authors: Farrell A. J.
Published: October 2005

A new technique for producing mechanically scanned acoustic holograms without reference beams is proposed. The instantaneous phase of the received acoustic signal is sampled at predetermined intervals. By altering the sampling point in time with scan position, an offset reference beam hologram is synthesized. The method allows the use of widely available ultrasonic nondestructive testing equipment, offering low-cost implementation of acoustic holography.
Two-Dimensional Anisotropic Acoustic Diffraction
Authors: Gates Edward
Published: October 2005

A scalar two-dimensional acoustic Green's function that is valid for particular orientations of several crystal classes is derived. The function is used to find expressions for aperture diffraction, array radiation, and radiation from a point source above a boundary. These results, if compared to similar calculations for isotropic media, show anisotropic variations that are dependent on the group velocity.
Shadowing of Randomly Rough Surfaces
Authors: Wagner R. J.
Published: October 2005

The first-order probability densities of height and slope on the portions of a rough surface illuminated jointly by rays in two arbitrary directions have been evaluated for a surface generated by a stationary normal random process. The dependence of the statistical properties of the apparent surface on the angles of incidence and observation is illustrated. For the case of backscatter, a simple calculation of the “shadowing functions,” valid at very small grazing angles, and a more detailed approximation, valid at the larger angles, are shown to be in excellent agreement with the computer-simulation results of Brockelman and Hagfors.
Refracted/Reflected Ray Transmissions in a Divergent Channel
Authors: Jacobson Melvin J. , Clark John G.
Published: October 2005

Refracted/bottom reflected ray transmissions in a divergent channel are studied when the sound velocity decreases linearly with depth. Ray geometry is examined in detail and, for a fixed source and receiving point, the number of arrivals, travel time, and spreading loss are found. For the source and receiving point on the channel bottom, bounds on the acceptable initial inclination angle, travel time, number of bottom reflections, and spreading loss are determined. Further, spreading losses in divergent and horizontal channels are compared. Spreading loss is also examined at all points along a ray emanating from a bottom source. In an example, bottom loss and bottom phase shift are superimposed upon spreading loss and travel-time phase shift, respectively, and the concept of bottom-induced interference is discussed.
Calculation of an Average Backscattering Coefficient of a Scattering Layer in a Frequency Band
Authors: Mohammed A.
Published: October 2005

The concept of a backscattering coefficient of a layer of isotropic scatterers averaged over a frequency band determined by the spectral characteristics of the transmitted signal and of the receiving equipment is introduced. The coefficient is evaluated for special cases of signal and receiver spectral shapes; numerical results of practical utility are included. The analysis neglects interaction effects among the scatterers and time variations of the medium.
Approximate Methods of Estimating Energy Spectra of Line Charges Fired under Water
Authors: Slifko John P.
Published: October 2005

An approximate method is discussed for estimating the energy spectrum of the shock-wave pulse from an end-detonated underwater explosive line charge of any weight and length, and at any angle of emission and range. This method requires only that the following quantities, which can be estimated, be known: (a) the impulse of an equivalent-weight ”point“ charge at the same range; (b) the shock-wave pulse-time parameter; (c) the frequency function for an approximate waveform generated at the emission angle of interest. Calculated results of energy-per-unit-area spectral density for several angles of emission are compared with experimental results for a 40-g 5-ft-long charge at 40-ft range and for a 2-lb 10-ft-long charge at 80-ft range. Also described is a method for scaling shock-wave energy spectra measured for one set of experimental conditions to the spectra for another set of conditions particularly for cases in which quantities (b) and (c) cannot be readily determined. This method is illustrated for complex waveforms resulting from line charges initiated simultaneously at several equally spaced points.
Criteria for Optimum-Signal-Detection Theory for Arrays
Authors: Edelblute David J. , Fisk Joanne M. , Kinnison Gerald L.
Published: October 2005

The purpose of this paper is to clarify the relationship between three different criteria for optimization of acoustic signal detection. Specifically, the maximization of array gain, the minimization of signal distortion, and the evaluation of the Neyman-Pearson likelihood ratio are shown to yield equivalent results at a single frequency.
Interaction of the Auditory and Visual Sensory Modalities
Authors: Brown A. E. , Hopkins H. K.
Published: October 2005

The general observation that dual sensory input enhances signal detectability is of considerable interest from the information-processing standpoint. Previous experiments on the effects of intersensory interaction have been concerned primarily with an observer's performance on a vigilance task. These studies have not produced results that are sufficiently precise to define the extent and manner of sensory interaction. This study is concerned with obtaining precise measurements of interaction occurring between auditory and visual sensory-information-processing networks. Separate auditory and visual threshold functions are determined and analyzed in terms of signal-detection theory. A bisensory threshold function is also determined, using equated stimuli levels derived from the individual sensory functions. The results of the bisensory test are compared to a theoretically derived curve based on the hypothesis of probabilistic adding and are found to have good correspondence.
Impact-Noise Rating of Various Floors
Authors: Mariner T. , Hehmann H. W. W.
Published: October 2005

The impact-noise transmission characteristics of approximately 75 floors have been examined using both the standard (ISO) hammer machine and real footfall as sources of excitation. The floors include concrete and wood-base construction, isolation layers, furred construction, simple and composite surfacing of various degrees of compliance, suspended ceilings. For each floor, the recently introduced Impact-Noise Rating (INR) derived from machine data is compared with the objective loudness computed from the spectrum of noise transmitted to the room below the floor when it is walked on by young women wearing hard-heeled, high-heeled shoes. The scatter of data confirms the authors' earlier conclusion that a rating method based on the standard hammer machine does not rank-order floors with adequate precision with respect to footfall noise. Floors having the same INR generally span a factor of 4 in loudness of hard-heeled female footfall. Floors producing the same loudness of footfall noise span in excess of 10 INR numbers. Since the loudness of transmitted hard-heeled footfall is self-consistent within ±10% (or approximately one INR number on the average), the observed discrepancy is fundamental, not due to poor technique.
Analysis of Pure-Tone Audiometric Responses in Relation to Speech Development in the Profoundly Deaf
Authors: Montgomery G. W. G.
Published: October 2005

The results of binaural audiometric tests of 83 profoundly deaf children were compared with their scores on a standardized speech test (the Phoneme Count), the American Medical Association (1947) audiogram-average assessment of percentage hearing loss for speech, and a qualitative diagnosis of speech defect. A contingency table of responses at 10-dB intervals against seven frequencies in both ears was compiled, and nonparametric analyses were undertaken to ascertain “speech frequencies” for this population. Mean standardized speech test scores per intensity interval appeared, by inspection, to be associated positively with residual hearing at all frequencies from 125 to 8000 cps in both ears, but a formal chi-square test of the association of speech scores and a response/no-response measure of each frequency from 125 to 8000 cps established significant relationships 4000 and 250 cps for the worse ear and at 2000, 250, 125, 1000, and 4000 cps for the better ear. The importance of lower frequencies as useful indicators of potential speech development in the profoundly deaf was noted, and the possibility of predicting eventual speech performance from the pure-tone audiogram was suggested. A lowering of frequency limits and a raising of the level of decibels above normal threshold was advocated for any audiogram-average method that sought to summarize hearing loss for speech for the profoundly deaf.
Measurement of the Piezoelectric Constant of Quartz at Gigacycle Frequencies
Authors: Carr Paul H.
Published: October 2005

The piezoelectric constants of selected samples of X-, AC-, and BC-cut quartz have been measured in the range 1–5 Gc/sec and are found equal to the static and megacycle values (i.e., d11 = 2.3 × 1012 and d14 = −0.67 × 1012 C/N) within an experimental uncertainty of 10%. This establishes that the piezoelectric constants of quartz are frequency-independent up to gigacycle frequencies. Gigacycle acoustic waves were generated at the end surface of a quartz rod places in the electric field of a re-entrant cavity. The piezoelectric constant was determined from a measurement of the cavity insertion loss and the cavity filling factor. A perturbation method has been developed for directly measuring the latter, which has previously been assumed to be unity. The method involves the use of perturbation theory to compute the filling factor, or equivalently, the electric field generating the acoustic waves, from a measurement of the decrease in the cavity resonant frequency when the rod is moved a small distance into the cavity. The piezoelectric constant of some quartz samples is less than that of the selected samples, and this decrease is attributed to defects in the optically polished end surface where the phonons are generated.
Critical Band in Binaural Detection
Authors: Mulligan B. E. , Mulligan M. J. , Stonecypher J. F.
Published: October 2005

In order to account for binaural improvements in detection on the basis of interaural phase shifts, or time deviations, it is necessary to assume that the “critical band” is a sinusoidlike process and that corresponding processes from the two ears interact. Support for this assumption is reported for the binaural conditions N0Sπ, NπS0, N0S0, N0Sm, and NπSm. It was found that neither interaural level nor bandwidth differences matter so long as the levels within the critical bands at the two ears are unaffected. Detection at one ear is affected only by a narrow band of frequencies at the opposite ear, thus confirming the assumption of a band-limited binaural interaction. Experiments were carried out with three different maskers: a narrow-band noise, a medium-band noise, and a medium-band noise with a gap in it. The narrow-band masker was as effective as the medium-band masker. The noise with a gap in it, however, produced a minimal release from masking when added at the nonsignal ear. These findings are discussed within the context of those of earlier investigations.
Effect of Diffusion on Ultrasonic Attenuation in Mixtures of the Rare Gases
Authors: Law Andre K. , Koronaios N. , Lindsay R. B.
Published: October 2005

The attenuation of 70-kHz sound in mixtures of helium and argon and of helium and krypton has been measured over a temperature range from 23° to 140°C and a pressure range from about 20 to 200 mm Hg. Kohler's theory of absorption due to diffusion in a mixture of two monatomic gases is found to account successfully for the measured excess absorption over that due to viscosity and thermal conductivity. Total absorption is found to increase slightly with temperature, a result that may be ascribed to the nonrigidity of the gas molecules. Generally good agreement is found with the previous room-temperature measurements of Petralia, Holmes and Tempest, and Stavseth.
Numerical Model of Coarticulation
Authors: Öhman Sven E. G.
Published: October 2005

The essential features of the coarticulation properties of Swedish dental stops in vowel-consonant-vowel contexts can be described by the formula s(x; t) = v(x; l)+k (t)[c(x) − v(x; t)]wc(x), where x represents the longitudinal distance between lips and glottis and s(x; t) denotes the shape of the vocal tract at some instant of time, t, during the vowel-consonant vowel utterance. The vowel component, v(x; t) is a linear combination of the three “extreme” shapes of the vowels /i/, /a/, and /u/ with weights that vary as functions of time. The consonant is represented by c(x), an ideal target shape, and wc(x), a so-called coarticulation function. A time varying factor k(t) represents the degree of excursion of the consonantal gesture. Vocal tract shapes measured from x-ray motion pictures of a set of Swedish vowel-consonant vowel utterances compare well with shapes generated by the formula. This result is consistent with our earlier conclusions about coarticulation, viz., that the vowel and consonant gestures are largely independent at the level of neural instructions.
Analysis of Acoustic-Emission Strain Waves
Authors: Egle D. M. , Tatro C. A.
Published: October 2005

An acoustic-emission loading and detection system is described and the detection system's harmonic response to both longitudinal and flexural waves is evaluated. Photographs of acoustic-emission response pulses are presented, and it is shown that the flexural waves are of considerable importance in describing the detection systems's response to the acoustic-emission source pulse. An estimate indicates that the energy of the flexural part of one acoustic-emission pulse is two orders of magnitude greater than the energy of the longitudinal part.
Resonance of a Bubble on an Infinite Rigid Boundary
Authors: Blue J. E.
Published: October 2005

The resonant frequency of a bubble attached to a rigid infinite plane in an infinite incompressible liquid was determined theoretically taking into consideration the angle of contact of the bubble with the plane. The resonant sizes at 33 and 36 kHz were determined experimentally by plotting the relative acoustic pressure (required to cause bubbles to jump one bubble diameter horizontally) versus the bubble radius and were found to be 76 and 67 μ, respectively. The experimental resonant sizes were found to be in good agreement with the theoretical resonant sizes. A small minimum on the plot can possibly be explained by using a Mathieu equation.
Comparison of Curvilinear and Linear Profile Approximation in the Calculation of Underwater Sound Intensities by Ray Theory
Authors: Pedersen Melvin A. , Gordon David F.
Published: October 2005

This paper presents the forms and curve-fitting techniques necessary for the calculation of ray-theory intensities for a curvilinear profile approximation in which continuity of slope as well as velocity is preserved. Using the Epstein profile as a control, this approximation is compared with various approximations that have slope discontinuities. The continuous-slope approximation does not display the artificial effects inherent in approximations with slope discontinuities, such as the introduction of spurious caustics, the omission of real caustics, and the generation of unrealistic regions of low intensity. However, artificial-layering effects in the form of infinite rates of change in intensity appear in the computations for the continuous-slope approximation because of discontinuities in the second derivative. The use of a new profile approximation that can preserve continuity of an arbitrary number of derivatives is suggested.
More on the Detection of One of M Orthogonal Signals
Authors: Nolte L. W. , Jaarsma David
Published: October 2005

Receiver operating characteristics (ROC's) for the classic problem of detecting the presence or absence of one of M orthogonal signals is presented. Previous results were valid for low detectability, for which the ROC is approximately normal (i.e., appears as a straight line with unit slope on normal normal probability paper) and the detectability depends on the logarithm of the number of possible signals M. For high detectability, however, the ROC departs from normality. In addition, the rate at which detectability decreases as M increases is more rapid than that predicted by the classical approximation.
Some Properties of Sound Transmission in the Middle and Outer Ears of Cats
Authors: Tonndorf Juergen , Khanna S. M.
Published: October 2005

With round-window cochlear microphonics serving as reference, sound pressure levels (SPL's) at the tympanic membrane (for acoustic inputs) and displacement amplitudes (for mechanical inputs to various middle-ear structures) were measured. The following results were obtained: (a) stapedial displacement for constant microphonics changes initially with −12 dB/oct, the curve flattening out gradually beyond 300 Hz; (b) slippage occur,in the incudo mallar joint below 50–60 Hz, increasing with inverse frequency; (c} the leverage ratio malleus/stapes is 2.2. A gradual lessening observed at higher frequencies may be due to an experimental artifact; (d) mallar displacement for constant SPL at the tympanic membrane is independent of frequency up to 600 Hz (bulla open; closed system), up to 2000 Hz (bulla closed, closed system), and up to 2500 Hz (bulla closed, open system); (e) the calculated input impedance of the tympanic membrane agrees quantitatively with results obtained by means of acoustic bridges; (f) the external ear canal contributes an additional pressure transformation (owing to its resonant properties) and also a small load effect upon the tympanic membrane; (g) the annular ligament of the stapes acts like a low-frequency attenuator (12 dB/oct) below 600 Hz; (h) at the cat's threshold of hearing, the displacement of the manubrium mallei is approximately 10−10 cm for 1000 Hz and about 10−11 cm for 5000 Hz.
Atmospheric Effects on Sonic Booms
Authors: Howes Walton L.
Published: October 2005

Whitham's equation for the sonic-boom-pressure signature is modified by using an invariant given by Blokhintsev in order to account for the effects of steady atmospheric variations on the boom. The resulting formula is expected to be useful for correlating experimental data. The atmospheric variations probably affect the boom primarily by wavefront distortion. When focusing of the wavefronts occurs, superbooms may result even from aircraft in uniform rectilinear flight.
Comments on “Flexural Vibrations of a Circular Ring When Transverse Shear and Rotatory Inertia are Considered” [J. Acoust. Soc. Am. 40, 372–375 (1966)]
Authors: Wilkinson J. P. D.
Published: October 2005

A correction is made to the boundary conditions given in the subject paper for the plate in the form of a circular sector bounded by concentric circles and polar radii.
Comments on “Aural Pulse Compression in Bats and Humans” [J. J. G. McCue, J. Acoust. Soc. Am. 40, 545–548 (1966)].
Authors: Strother Greenville K.
Published: October 2005

A reply to recent criticism of a letter written in 1961, on the possible use of pulse compression by bats for echolocation, is offered. The original proposal was, and still remains, technically feasible; this is explained in detail. Several articles published since 1961 have been devoted in part to the original proposal with the result that it now appears unlikely that a bat uses an equivalent pulse compression network, but the premise is not disproved. A more interesting (although closely related) problem is how the mixed frequency-modulated and continuous-wave pulses are processed by the bat's hearing mechanism.