bluuebunny/crossref_metadata_2025 huggingface dataset:
Generalized Kirchhoff approach to the ocean surface-scatter communication channel. Part II: Second-order functions
Authors: Ziomek Lawrence J.
Published: October 2005

Three second-order functions which characterize the ocean surface-scatter communication channel are derived from the transfer function of the ocean surface. These second-order functions include the two-frequency correlation function or the two-frequency mutual coherence function, the scattering function, and the power spectral density function of the scattered acoustic pressure field. These functions are shown to be dependent upon the general form of the directional wavenumber spectrum. Both the slightly rough and very rough surface cases are included. The interrelationships which exist amongst these functions are demonstrated. As an example, the power spectral density function is computed for the very rough surface case using the Neumann–Pierson directional wavenumber spectrum.
Inverse frequency dependence of simultaneous tone-on-tone masking patterns at low levels
Authors: Zwicker E. , Jaroszewski A.
Published: October 2005

Using the Békésy tracking method, tone-on-tone masking patterns were measured with eight subjects at eight masker frequencies between 250 Hz and 6.03 kHz. Masking patterns were obtained for five masker levels between 20 and 60 dB SPL. Test-tone frequencies were chosen within two critical bands above and below the masker frequency. A level-dependent frequency asymmetry of masking was observed at all masker frequencies except at 250 Hz. At low levels there was a greater spread of masking towards the lower frequencies than toward the higher frequencies, but at high levels there was a greater spread of masking towards the higher frequencies than toward the lower frequencies. Only at masker levels of 40 dB SPL were the masking patterns approximately symmetrical.
Acoustic propagation in a rigid torus
Authors: El-Raheb Michael , Wagner Paul
Published: October 2005

The acoustic propagation in a rigid torus is analyzed using a Green’s function method. Three types of surface elements are developed; a flat quadrilateral element used in modeling polygonal cavities, a curved conical element appropriate for surfaces with one curvature, and a toroidal element developed for such doubly curved surfaces as the torus. Curved elements are necessary since the acoustic pressure is sensitive to slope discontinuities between consecutive surface elements especially near cavity resonances. The acoustic characteristics of the torus are compared to those of a bend of square cross section for a frequency range that includes the transverse acoustic resonance. Two equivalences between the different sections are tested; the first conserves curvature and cross-sectional dimension while the second matches transverse resonance and duct volume. The second equivalence accurately matches the acoustic characteristics of the torus up to the cutoff frequency corresponding to a mode with two circumferential waves.
Torsional dispersion relations of waves in an infinitely long clad cylindrical rod
Authors: Parnes R.
Published: October 2005

The dispersion relations of torsional waves propagating in a system consisting of an elastic rod of radius a embedded in a linear elastic medium are investigated. Phase speeds of waves of wavelength λ which propagate under steady-state conditions are determined. The dispersion relations are found to be dependent on the geometric ratio a/λ, as well as on nondimensional ratios of the rod-medium properties. The frequency equation obtained is analyzed and upper and lower bounds on the phase speed are determined. It is shown that torsional waves can propagate freely only if the propagation speed of torsional waves in the corresponding free rod is less than that of shear waves propagating in the medium. Results are presented by means of dispersion curves and surfaces.
Coherence and multiple scattering effects on acoustic backscattering from linear arrays of gas-filled bubbles
Authors: Bruno Daniel R. , Novarini Jorge C.
Published: October 2005

Acoustic backscattering of spherical waves from finite linear arrays of gas-filled bubbles, both regular and randomly spaced, is studied numerically including coherence and acoustic interaction to all orders between bubbles. Coherence effects are first examined neglecting multiple scattering. Large effects are observed and the single bubble resonance can be appreciably distorted. The combined effect of coherence and multiple scattering is studied through an interaction parameter which relates the total scattered field intensity and the single scattering incoherent intensity. Regular arrays resonate at the single bubble resonance frequency and when the bubble spacing is a multiple of the incident wavelength. Close to the array, coherence is predominant over multiple scattering. In the farfield, multiple scattering causes an enhancement of the intensity, depending on the bubble spacing. For random arrays only the single bubble resonance subsists and multiple scattering produces a decrement of the field intensity for any average bubble spacing.
Measurement and prediction of annoyance caused by time-varying highway noise
Authors: Yaniv Simone L. , Danner William F. , Bauer Jay W.
Published: October 2005

Twenty-eight audiologically normal adult subjects participated in a study designed to assess how well six noise-rating indices would predict the annoyance caused by 3-min recorded samples of traffic noise obtained from both nominally constant-speed and stop-and-go traffic. The study was performed in a laboratory simulating a home environment. Annoyance judgments were obtained through the use of a magnitude estimation technique involving a 10-point scale. Subjects were also asked if they could accept each of the 24 traffic sounds if heard on a regular basis in their homes. Data obtained indicate that the simpler noise-rating indices, such as the average sound level and the level exceeded 10% of the time, predict annoyance as well as, if not better than, complicated schemes incorporating a measure of either variability or rate-of-change of levels with time. Thus it appears that the measurement and computational burdens associated with these complicated schemes are unwarranted.
Vibration and stability of a two-layered beam with imperfect bonding
Authors: Chonan S.
Published: October 2005

This paper is a study of the vibration and stability of a two-layered beam with imperfect bonding subjected to axial and tangential loads. The beam consists of two identical layers joined together by a bonding agent. The normal and shear bond stresses at the interface of the layers are taken to depend on the respective relative vertical and horizontal displacements of the layers. Each layer is assumed to bend according to the Timoshenko beam theory. It is found that the modes of vibration are divided into three classes, that is, the bending mode, the thickness-stretch mode, and the longitudinal mode. The flutter and divergence instability loads are obtained for clamped-free beams and are shown graphically as functions of the shear and normal stiffnesses of the bond. The numerical results are also compared with those from the classical Euler beam theory.
The effect of near-surface layering on the reflectivity of the ocean bottom
Authors: Holthusen Helmut , Vidmar Paul J.
Published: October 2005

The effect of near-surface layering in marine sediments on the plane-wave reflection coefficient R of the ocean bottom is examined using a numerical model. A comparison of bottom reflection loss, BRL = −20 log10 (‖R‖), from a 500-m-thick sediment with and without realistic near-surface layering shows that additional reflections from the layering can reduce 1/3- octave averaged BRL (BRLA) by more than 10 dB at 1600 Hz for grazing angles above 20°. This results in a frequency inversion since, at lower frequencies, the effect of the layering is much smaller; at 50 Hz there is almost no effect. An important feature of this dramatic decrease in BRLA is its relative independ- ence from the details of the layering structure. However, the exact nature of the layering does have an important effect on BRL and the phase of R at a single frequency, and on BRLA at about 800 Hz. Studies of an artificial layered structure made up of equally spaced, identical layers show that the physical process producing the decrease in BRL is a collective effect of the layered structure and is related to the constructive interference of reflections from each of the layers.
Axisymmetric wave propagation on a conical shell
Authors: Fletcher N. H.
Published: October 2005

Equations are derived to describe the propagation of axially symmetric waves generated at the apex of a conical shell, taking into account the coupling between longitudinal and transverse waves. A form of approximate solution is proposed, based upon the Green’s function for wave propagation on a flat plate but containing several variational parameters, the number of which can be reduced to one if additional approximations are made. It is shown that the region of the cone near the vertex moves amost like a rigid body, but the motion becomes wavelike at a distance from the vertex which decreases rapidly with increasing frequency, and at large distances the propagation is essentially the same as on a flat plate. The one-parameter approximation is investigated numerically for two realistic situations, and appropriate solutions are presented and discussed.
Reflection of elastic waves under initial stress at a free surface: P and S
V motion
Authors: Chattopadhyay A. , Bose S. , Chakraborty M.
Published: October 2005

The phenomenon of reflection of elastic waves at a free surface of an initially stressed sandy medium has been studied here. The reflection coefficients have been computed numerically for both P and SV motion. The variations of reflection coefficients for different values of η, initial stress parameter, and angle of incidence have been represented graphically. The effects of initial stress and sandiness of the layer on surface waves have also been studied. To the best of our knowledge the idea of a sandy medium under initial stress is a new one which is physically possible. Taking into consideration of the theories given by Weiskopf [J. Franklin Inst. 239, 445 (1945)] and Biot [Mechanics of Incremental Deformations (Wiley, New York, 1965)] the equations of motion have been deduced here.
Directivity index of arrays of random line arrays
Authors: Lockwood J. C. , Thorn J. V. , Booth N. O.
Published: October 2005

The directivity index of a random array of random line arrays is analyzed statistically. Expressions are obtained for the ensemble average and variance of the directivity index for the general case of an array of random line arrays. These expressions are applied to the specific case of line arrays distributed with uniform pdf in a circular region, and both the average and the variance of the directivity index are approximated in closed form. The closed-form expressions are evaluated for a variety of parameter combinations to show the effects of number of elements per line, array dimensions, and array steering. The closed-form expression for directivity index is validated by comparison of its calculated results with those of a more exact numerical integration technique.
Obstruent production by hearing-impaired speakers: Interarticulator timing and acoustics
Authors: McGarr Nancy S. , Löfqvist Anders
Published: October 2005

This study examines the organization of laryngeal control and interarticulator timing in the production of obstruents and obstruent clusters by three severely–profoundly deaf adults. Glottal activity was monitored by transillumination; temporal patterns of oral articulation (lips and tongue–palate) were recorded using an electrical transconductance technique. For each of the deaf speakers, an inappropriate abduction gesture was often found between words, a pattern never observed for hearing speakers. At the same time, the deaf speakers differed from each other with respect to types of errors, variability, and interarticulator coordination. For the most intelligible speaker, the timing of glottal opening with respect to oral articulation was most like that observed for normals. The second deaf speaker often failed to observe voicing contrasts with respect to glottal opening. This subject was nevertheless consistent in producing most plosives without a glottal opening, and all fricatives with an opening gesture. For the third deaf speaker, the pattern of errors was more complex and included both missing and inappropriate glottal opening gestures.
Mechanisms of flow-excited cavity tones at low Mach number
Authors: Elder S. A. , Farabee T. M. , Demetz F. C.
Published: October 2005

Cavity tone spectra have been investigated as a function of wind speed in a low noise wind tunnel, at Mach numbers below 0.2. The cavity, a cylindrical closed pipe with a rectangular slot for a mouth opening, was flush mounted in the side of a flat plate, 30-in. downstream of the leading edge. Both laminar and (tripped) turbulent boundary layer effects were explored. Contributions to tone generation from turbulent boundary layer fluctuations, acoustic background noise, sheartone feedback coupling, and cavity resonant feedback coupling are quantitatively sorted out on the basis of theoretical models. A theory of laminar pipetones, complementing an earlier model of turbulent pipetones, is used as a basis for explaining sheartone/pipetone interaction. An empirical correction curve is introduced to take into account the slowing of wave speed in thick shear layers.
On evaluation of noises in solid media
Authors: Beltzer Abraham , Parnes Raymond
Published: October 2005

The paper formulates the problem of evaluating random noises in an elastic medium by means of the diffraction due to the presence of an inclusion. The solution is given for the case of an embedded rigid cylinder and conclusions are made on the values of governing parameters which would provide a more accurate evaluation.
Coupled amplitude theory of nonlinear surface acoustic waves
Authors: Kalyanasundaram N. , Ravindran R. , Prasad P.
Published: October 2005

The nonlinear propagation characteristics of surface acoustic waves on an isotropic elastic solid have been studied in this paper. The solution of the harmonic boundary value problem for Rayleigh waves is obtained as a generalized Fourier series whose coefficients are proportional to the slowly varying amplitudes of the various harmonics. The infinite set of coupled equations for the amplitudes when solved exhibit an oscillatory slow variation signifying a continuous transfer of energy back and forth among the various harmonics. A conservation relation is derived among all the harmonic amplitudes.
Structure and duration of vowels together specify fricative voicing
Authors: Soli Sigfrid D.
Published: October 2005

The durations of vowels specify several types of linguistic information. Thus multiple durational cues may be decoded from the same temporal interval of the signal, a situation which should create perceptual ambiguity. Four perceptual studies of postvocalic fricative voicing examined how information in the duration and dynamic structure of the vowel might combine to resolve these ambiguities. Stimuli were made by varying the duration and structure of vowels from utterances of /jus/ and /juz/. In the first experiment vowel structure differences influenced voicing judgments by 30%–40%. The second experiment showed that the offset characteristics of the /juz/ vowel were not the major vowel structure cues in the first experiment. The third experiment examined identification and discrimination of stimuli with neutral vocalic voicing cues which differed only in friction duration. Even with these stimuli, friction duration was a weak and poorly discriminated voicing cue. The fourth experiment showed that variations in the structure and duration of vowels are specific to the voicing contrast and minimally influence vowel identification. Acoustic analyses of /jus/ and /juz/ produced at normal and rapid rates revealed that the proportional durations of the semivowel transitions and vowel steady state differed reliable before /s/ and /z/, regardless of total vowel duration. Before /s/ the steady-state duration was approximately 45% that of the entire vowel, as compared with 65% before /z/. These proportional values remained stable across talkers and speaking rates. Postvocalic fricative voicing contrasts apparently may be encoded in the relative timing of articulatory events which produce the entire voiced portion of the syllable. Attunement to both the structure and duration of vowels as sources of perceptual information may then account for the minimal ambiguity of linguistic contrasts assumed to be cued by differences in vowel duration.
An infrared sensor using the high temperature-dependent performance of a liquid delay line oscillator
Authors: Toda Kohji , Urabe Heijiro
Published: October 2005

An infrared sensor using a liquid delay line oscillator is described. The delay line consists of two pairs of interdigital transducers operating at a liquid–solid interface and a thermal absorber used as a reflecting plate of the sound wave propagating in the liquid. The oscillation frequency of the device changes significantly under the influence of irradiation from a blackbody or a laser in the infrared region. The device performances as an infrared sensor are given.
Ultrasonic determination of thermodynamic threshold parameters for irreversible cutaneous burns
Authors: Cantrell John H.
Published: October 2005

I n vivo ultrasonic measurements of the depth of conductive cutaneous burns experimentally induced in anesthetized Yorkshire pigs are reported as a function of burn time for the case in which the skin surface temperature is maintained at 100 °C. The data are used in the solution of the one-dimensional heat diffusion equation with time-dependent boundary conditions to obtain the threshold temperature (65.3 °C) and the energy of transformation per unit mass (408 J ⋅ g−1) associated with the transition of the tissue from the state of viability to the state of necrosis. The simplicity of the mathematical model and the expediency of the ultrasonic measurements in studies of thermal injury are emphasized.
Low-frequency hearing sensitivity in the echolocating bat, E
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Authors: Poussin C. , Simmons J. A.
Published: October 2005

Echolocating bats of the species Eptesicus fuscus use sound at frequencies of 10 to 100 kHz for sonar or for acoustic social communication, and they hear these ultrasonic frequencies very well. Eptesicus also has a lower-frequency region of auditory sensitivity from 200 Hz to 5 kHz. They may use these lower frequencies to detect and identify insect prey by passive hearing of the insect’s own sounds. The hearing of Eptesicus at low frequencies is tuned to 0.7 to 1.3 kHz, indicating that some specialization of the auditory system, perhaps in the external or middle ear, underlies the capacity to hear these lower frequencies. The results also suggest some specific role for low-frequency hearing in the bat’s life, and it is known that Eptesicus orients towards the sounds produced by insects under natural conditions.
A new theory for multitone masking
Authors: Martens Jean-Pierre
Published: October 2005

In order to explain masked thresholds of a tonal probe centered between two tone maskers, Green [J. Acoust.Soc. Am. 37, 802–813 (1965)] introduced his famous energy-detection model. We argue that the model is in some respects inadequate and inconsistent with measurements of roughness, at least one psychological correlate of temporal fluctuations. Furthermore, it requires the assumption that tones interact over frequency distances considerably beyond a critical bandwidth. Therefore we propose an alternative theory that allows reconciliation of Green’s measurements with the commonly accepted critical band hypothesis. Our model is based on the hypothesis that the auditory system is capable of performing a spectral analysis of the time pattern of the waveform envelope. Important effects of probe type (noise, tone, or complex) and phase between masker and probe seem easily explained by the model. Also, the differences between two- and four-tone masking are successfully predicted. Finally, as a byproduct, our theory offers an explanation for the just noticeable amplitude modulation (AM) and frequency modulation (FM) of a sinusoidal carrier.
Ultrasonic imaging system using Doppler-modulated wave fronts
Authors: Sasaki Osami , Kirii Yuuji , Kitazawa Yoshikado
Published: October 2005

A new imaging method is proposed which reconstructs a stationary image at any time of a vibrating object from a hologram synthesized with Fourier coefficients of the detected signal over a few periods of the vibration. This signal arises from receiving time-varying ultrasonic waves frequency shifted by the Doppler effect. The signal processing of the new method produces some special features such as reduction of noise, elimination of stationary objects, and selective reconstruction of the object vibrating with a specified frequency. The computer simulations and the basic experimental results show the effectiveness of the imaging method.
Simplified technique for the evaluation of airborne sound insulation in buildings
Authors: Taibo Lucia N. , de Dayan Hilda Glasserman
Published: October 2005

In the present work, a simplified technique for the measurement of airborne sound insulation in buildings, is proposed. This procedure deals with the known measurement of average A-weighted levels in source and receiving room and introduces an average correction factor ??(A) due to the reverberation time of the receiving room, thus avoiding the systematic measurement of this magnitude. The correction factor ??(A) was obtained by averaging 66 reverberation times, measured in dwelling units and offices, with volumes between 25 and 100 m3, with typical furnishing and linings. From a population of 4620 data (70 sound reduction index curves and the 66 measured reverberation times), a sample of 100 random combinations was extracted. From these values the standardized index IA(STC), as well as a new parameter R′A, derived from dB(A) measurements, ??(A) and the classical correction factor due to the receiver volume and the sample surface, were obtained. A closely linear relationship between both indexes (IA = 1.05RA −11.7; r = 0.99) has been found. The sample and prediction confidence intervals of the fitted line, were calculated. Subsequently, the airborne sound insulation of 25 building elements, consisting of compound demountable partitions, gypsum boards of different widths, gypsum or wooden ceilings, etc., by both standardized and proposed techniques has been measured. The attained new values were located within the prediction interval of ±2.7 dB along the fitted regression line.
Vibration and stability of stiffened annular plates
Authors: Irie Toshihiro , Yamada Gen , Aomura Shigeru
Published: October 2005

The vibration and stability of radially stiffened annular plates subjected to an in-plane force uniformly distributed at the edges are analyzed by the energy method. For this purpose, the transverse deflection of a stiffened annular plate is written in a series of the products of the deflection function of a sectorial beam with a small angle and the trigonometric function of angular coordinate. The deflection function of the sectorial beam is approximately expressed by a quintic spline function satisfying the boundary conditions at the edges, and the frequency equation of the plate is derived by the Ritz method. The method is applied to annular plates with several stiffeners of uniform rectangular cross section located at equal angular intervals; the natural frequencies and the critical buckling loads are calculated numerically and the effects of stiffeners on them are studied.
Boundary reflection/diffraction effects and the parabolic-equation split-step algorithm
Authors: Dicus Ronald L.
Published: October 2005

Computations with the parabolic-equation (PE) split-step Fourier algorithm are compared with normal-mode and diffraction theories to evaluate the accuracy of PE-computed fields above a reflecting faceted boundary. All computations are made for a 10-Hz source in a uniform sound-speed medium overlying reflecting facets each consisting of a fluid layer with a specified reflection critical angle, this angle being the same for all facets. The PE-computed field above an infinite plane is shown to agree with normal-mode theory to within 2 dB when allowance is made for small range shifts. Diffraction effects (difference between exact and ray-theoretical fields) as large as 10 dB in both the total field and vertical angular power spectral density are demonstrated for boundaries composed of one or two semi-infinite plane facets. PE and diffraction-theory computations of the field above the faceted boundaries generally agree within 2 dB except for small range shifts. Agreement in computed angular power spectral densities is generally within 1 dB when allowance is made for small angular shifts less than one degree. Although range-specific angular power spectral densities from fluid and solid facets differ, range averaging leads to a common power spectrum. Implications are discussed for using a three-dimensional PE algorithm for modeling faceted sediment or rock bottoms.
Vibrations of nonhomogeneous plates of variable thickness
Authors: Tomar J. S. , Gupta D. C. , Jain N. C.
Published: October 2005

A simple model is presented for use by research workers in engineering design and technology where the investigations are devoted to the nonhomogeneous elastic bodies of variable thickness. The nonhomogeneity in materials arises due to imperfections in the material and therefore in nonhomogeneous elastic bodies the material properties are not constant but vary with the position in a random manner. Plywood, timber, delta wood, or fiber reinforced plastics are some examples. Further, some other high strength composites such as glass epoxy or boron epoxy are recent innovations.
The acoustical structure of highly porous open-cell foams
Authors: Lambert Robert F.
Published: October 2005

This work concerns both the theoretical prediction and measurement of structural parameters in open-cell highly porous polyurethane foams. Of particular interest are the dynamic flow resistance, thermal time constant, and mass structure factor and their dependence on frequency and geometry of the cellular structure. The predictions of cell size parameters, static flow resistance, and heat transfer as accounted for by a Nusselt number are compared with measurement. Since the static flow resistance and inverse thermal time constant are interrelated via the ’’mean’’ pore size parameter of Biot, only two independent measurements such as volume porosity and mean filament diameter are required to make the predictions for a given fluid condition. The agreements between this theory and nonacoustical experiments are excellent.
Note on fine structure models in underwater acoustics
Authors: Desaubies Yves
Published: October 2005

Some of the assumptions on which two recent papers [Flatté et al., J. Acoust. Soc. Am. 68, 1771–1779 (1980); Unni and Kaufman, J. Acoust. Soc. Am. 69, 676–680 (1981)] on sound scattering by ocean fine structure are based, are discussed.
The multipath coherence function for uncorrelated underwater channels
Authors: Graham William J.
Published: October 2005

A new measure is introduced for determining the coherence of acoustic signals in multipath channels which have random fluctuations that are uncorrelated between them. The analysis is based upon a formulation of the spectral coherence function in terms of the random multipath channel transfer functions. The derived coherence function allows each channel to be analyzed individually, and separates the effects of random fluctuations from the effects of deterministic multipath interface (frequency selective fading). Examples of applications are given to determining the effects of independent sensor motion on coherence, and the effects of internal waves on signal coherence between widely spaced receivers.
Effects of transducer motion on echo-integration techniques
Authors: Stanton T. K.
Published: October 2005

Deviations in a time-integrated sonar-echo signal caused by angular motion of the sonar transducer have been calculated. The effects are due to the change in orientation of the transducer between the times of transmission of the acoustic pulse and reception of the resultant echoes. The transmission and reception beams are then aimed in different directions than in the static case. If the beams are narrow enough in relation to the augular displacement, then the departures of the integrated echo from the static case will be significant. The deviations are presented for several beamwidths as a function of angular displacement of the transducer. The results quantify the expected outcome—the change in echo-integration values from the corresponding static case increases with both increasing angular displacement and decreasing beamwidth. In an example calculation, a ship-mounted transducer is shown to roll in conjunction with the ship an angle of 4° between the times of transmission and subsequent reception of echoes from a collection of randomly distributed 400-m-deep targets. It is demonstrated that for a circular transducer, the deviations in this case can range from 1.4% to 64% for beamwidths of 40° down to 5°, respectively.
Forward masking of auditory nerve (N1) and brainstem (wave V) responses in humans
Authors: Kramer S. J. , Teas D. C.
Published: October 2005

Wave V of the auditory brainstem response and N1 from the ear canal were recorded from normal hearing adults using a forward masking paradigm. Response amplitudes and latencies to 40 dB HL probe clicks presented in quiet and as a function of the time delay (ΔT) following short-duration wideband noise maskers were measured. The masking effects for wave V were different than for N1. The primary effects were decreases in N1 amplitude and increases in wave V latency, neither of which were recovered by ΔT = 100 ms. The V–N1 latency interval increased for ΔTs below 50 ms. Wave V amplitude was fully recovered by ΔT = 25 ms, even though N1 amplitude was significantly reduced. Recovery functions are also described for some variations in masker duration and masker level. Results are explainable in terms of peripheral and central processes or entirely peripheral processes. The differential effects of N1 and wave V suggest, at least for some stimulus conditions, that these two responses are to some degree independent of each other.
Collection of equivalent circuit representations of electric-field coupled and magnetic-field coupled transducers
Authors: Thompson William
Published: October 2005

Three new lumped element equivalent circuits, one for an electric-field transducer and two for a magnetic-field transducer, are discussed. For completeness and ease of comparison, however, a set of four equivalent circuits, many of which are familiar, is presented for either type. Each circuit correctly predicts the electromechanical terminal pair behavior of the transducer in the frequency neighborhood of an isolated mechanical resonance. In half of the circuits, electromechanical coupling is represented by an ideal transformer while in the other half, an ideal gyrator must be used. As a consequence, in half of the circuits the mechanical domain can be represented by an impedance-type analog, while in the remaining half, a mobility-type analog must be used. Some for the new equivalent circuits are suggested.
Reply to Cole’s ’’Comments on ’Thermodynamic corrections to the velocity of propagation in a bubbly medium’’’ [J. Acoust. Soc. Am. 72, 1066 (1982)]
Authors: Floyd Edward R.
Published: October 2005

This letter rebuts Cole’s comments.
Sound scattering by rigid and elastic infinite elliptical cylinders in water
Authors: Pillai T. A. K. , Varadan V. V. , Varadan V. K.
Published: October 2005

Numerical results are presented here to the problem of scattering of acoustic waves from infinite elastic elliptic cylinders under water. The T-matrix (or null field) method has been used to evaluate the scattered field coefficients. Comparisons have been drawn between the form functions of a rigid (acoustically hard) cylinder and an elastic cylinder of similar geometry. The smooth periodic form function of the rigid cylinder is analyzed on the basis of the existence of Franz waves (creeping waves), while the sharp peaks in the elastic cylinder case have been interpreted as due to resonance effects of the submerged cylinder. Though, in general, it is possible to distinguish between the two kinds of targets from the scattering pattern (polar plots at fixed frequencies), it is observed that at ka = 5.0, one cannot distinguish between a rigid cylinder and an elastic cylinder.
A classification and comparison of vocalizations of captive killer whales (O
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Authors: Dahlheim Marilyn E. , Awbrey Frank
Published: October 2005

An acoustical study was conducted on captive killer whales (Orcinus orca) to determine if individuals or groups differed in their vocalizations. Twenty-one different underwater vocalization categories produced by 13 animals were recorded within a 40 Hz to 20 kHz bandwidth. Eight acoustical variables (starting and ending frequencies of the signal, duration, harmonic interval, starting and ending frequencies of the fundamentals, and low and high concentration of energy) were measured for each vocalization. multivariatediscriminant analysis was used to determine whether individual, oceanarium, or sexual differences were detectable in their vocalizations. Results showed distinct acoustical groupings by individuals, by oceanariums, and by sex.
A cochlear nonlinear transmission-line model compatible with combination tone psychophysics
Authors: Furst Miriam , Goldstein Julius L.
Published: October 2005

Human psychophysical measurements of the cubic combination tone (2f1− f2) have shown that at low and moderate stimulus levels its phase decreases at 6°–12° per dB increase in stimulus level. This finding contrasts with physiological measurements in anaesthetized animals where the CT phase is insensitive to stimulus level. We have characterized quantitatively the difference in cochlear nonlinear response between humans and animals in terms of a cochlear nonlinear transmission line model having different nonlinear elements for human and animal. Following Hall [J. Acoust. Soc. Am. 56, 1818–1828 (1974)], a nonlinearity was introduced in the resistance of the cochlea partition (model A) for describing the animal cochlea. To model the human cochlea, we found that adding a nonlinear stiffness to the nonlinear mechanical loading of the basilar membrane gave the correct phase-amplitude dependence (model B). Simulation was used to solve the nonlinear models in the time domain. For high amplitude stimuli, both models predict similar results, mainly saturation in the response. The significant differences between the models occur at low and moderate stimulus intensities. According to model B the site of the resonant frequency along the basilar membrane depends on the stimulus level, while it is independent of stimulus level according to model A. As a result of the shift in the resonant site location in model B, the phase response profile is shifted as well, so that the phase response at the original resonant site depends on stimulus level. The psychophysical data on CT cancellation were predicted by model B, while physiological data on CT cancellation are predicted by model A.
The behavior of acoustic distortion products in the ear canals of chinchillas with normal or damaged ears
Authors: Zurek Patrick M. , Clark William W. , Kim D. O.
Published: October 2005

Acoustic intermodulation distortion products were measured in 15 ear canals of chinchillas with normal or damaged ears. Pretreatment results showed that when two primary tones at frequencies f1 and f2, f1<f2, were presented at levels from 30 to 90 dB SPL, acoustic distortion products at 2f1−f2 and 2f2−f1 were 30 to 50 dB below primary-tone levels. Noise exposures that caused temporary or permanent hearing loss produced corresponding temporary or permanent reductions in distortion-product levels. Mechanical damage to the cochlea or middle ear reduced the distortion-product levels to below the noise floor of the measurement system. Comparisons of distortion-product level with behaviorally measured threshold shift and cochlear histopathology suggest that, in the absence of conductive impairment, the level of 2f1−f2 or 2f2−f1 can be used as a sensitive indicator of hearing sensitivity and the condition of the cochlea.
A basic problem of resource allocation in target tracking
Authors: Psaraftis Harilaos N. , Perakis Anastassios N.
Published: October 2005

Stochastic dynamic programming techniques are used to formulate and solve the problem of tracking two independent and stationary targets with one sensor in order to maximize a certain measure of performance. At any point in time, the sensor, usually a passive sonar array, can be allocated to only one of the two targets. Assuming the fluctuation process in the ocean to be governed by a phase-random multipath law, the sensor ’’holds’’ the target when ρ, the root-mean-square pressure at the receiver, is above a user-specified threshold. Using discrete time models for the ocean acoustic detection process formulated in earlier papers, we solve the problem for a finite horizon of observations using several alternative objective and reward/penalty functions. Delays of user-specified magnitude in ’’switching’’ from one target to the other are also incorporated in our algorithms. Examples using both real and simulated data are presented and discussed. Finally, future research directions are suggested.
An ultrasound power meter
Authors: Engan Helge
Published: October 2005

An ultrasound power measuring method based on measurement of the radiation force is described. The method requires no target to measure this force since the force is measured at the holder of the ultrasonic transducer that is transmitting. The actual power meter reported is based on modulated acoustic transmission to facilitate electronic detection and measurement.
Consonant-feature transmission as a function of presentation level in hearing-impaired listeners
Authors: Gutnick Howard N.
Published: October 2005

Normal-hearing listeners and listeners with a high-frequency sensorineural hearing loss identified 17 consonants as part of a consonant-vowel syllable with /a/ or /i/ as the vowel. The syllables were set at presentation levels of 10 to 65 dB re thresholds at 1000 Hz. The performance for the consonants comprising each of 11 a priori acoustic-phonetic features improved directly with increases in presentation level for both subject groups, but was better in the /a/ than in the /i/ context. The performance of the hearing-impaired listeners was significantly poorer than the performance of the normal-hearing listeners only for the higher-frequency features of frication and sibilance. The lower-frequency features of voicing and sonorance were reflected in the confusion matrices of hearing-impaired listeners at presentation levels of 10 and 20 dB; only at 35 to 65 dB were higher-frequency features transmitted in the confusion matrices of this group.
Tactile communication of speech: II. Comparison of two spectral displays in a vowel discrimination task
Authors: Clements M. A. , Braida L. D. , Durlach N. I.
Published: October 2005

Vowel discrimination experiments were performed comparing two tactile, Optacon-based, spectral displays: a frequency-amplitude (FA) display and a time-swept (TS) display, The set of vowel pairs tested consisted of all pairs from the set of ten American nondipthongized vowels. One set of materials consisted of natural /b/-V-/t/’s (with each vowel represented by 12 utterances generated by four speakers producing each vowel three times). A second set consisted of synthetic vowels (with each vowel represented by a single waveform). On the average, the score obtained with the second set of materials was substantially better than with the first (92% vs 79%); the score obtained with the TS display was slightly better than with the FA display (87% vs 83%); the feature best differentiated was tenseness, followed by the features high and low, then by round and back, and finally by retroflexion; and the correlation between discrimination performance and the physical parameters duration, amplitude, F1, and F2/F1 (taken singly) was relatively weak. In general, the results of this study, together with those of other studies previously reported, suggest that the two displays studied are far from optimum.
Subjective speech-to-noise ratio as a measure of speech quality for digital waveform coders
Authors: Nakatsui Mamoru , Mermelstein Paul
Published: October 2005

The ultimate performance measure for evaluating voice communication systems is the subjective quality of the received speech. Modern digital speech-coding techniques achieve high intelligibility and significant transmission economies. The high level of speech intelligibility is a necessary but insufficient condition for user acceptance of the systems. Quality, as well, must meet acceptability criteria. However, no adequate single measure of overall speech quality has yet been developed. This work takes a utilitarian approach in attempting to satisfy the urgent requirement for a practical measurement method. The subjective speech-to-noise-ratio (SNR), derived from the forced-choice pair-comparison test using the psychometric analysis procedure commonly used in the method of constants, is evaluated. A speech signal degraded by varying amounts of multiplicative white noise is selected as the reference system in the test. Seven types of digital speech coders are simulated and evaluated in this study, including log-PCM, ADM, ADPCM coders with variable or fixed predictor, APC, residual-excited and pitch-excited LP coders (RELP and LPC). Thirteen configurations of these coders covering the transmission bit rates of 2.4 to 64 kb/s are included. Pair-comparison tests were conducted in two separate sessions 14 months apart using different groups of speakers and listeners. The subjective SNR estimated from 13 coder configurations ranges from 7 to 40 dB and well represents overall speech quality in a single dimension. No significant speaker and listener variation is found for a wide range of waveform coders. The subjective SNR estimate is found to be highly reproducible with different speakers and listeners. Arbitrary selection of as few as five listeners yields a stable subjective SNR estimate for the waveform coders. On the other hand, highly significant listener variation is found for the narrow-band digital vocoders (RELP and LPC). This listener variability reflects a limitation of the measure that may prevent its extension to vocoded speech whose distortions differ significantly from those of the reference speech.
From text to speech with SRS
Authors: Hertz Susan R.
Published: October 2005

SRS (Speech Research System) is a highly flexible computer system for the development of text-to-speech rules for any language. Its powerful interactive facilities and special rule language have been designed to facilitate rule development by programmers and nonprogrammers alike. The system has been used for instruction in acoustic phonetics, for the generation of stimuli for perceptual experiments, and for the development of synthesis rules for a variety of languages. This paper focuses on the SRS rule framework, which allows users to express four kinds of rules that apply in succession to convert text to sound. The paper also illustrates the user-oriented nature of the SRS interactive facilities, and describes the system’s implementation and use.
Rebuttal by Karl D. Kryter to comments by T. J. Schultz
Authors: Kryter Karl D.
Published: October 2005

This paper contains further evaluation of Leq measures obtained in the French and German aircraft noise studies, and a rebuttal to comments made by T. J. Schultz [J. Acoust. Soc. Am. 72, xxx–xxx (1982)].[AIP]
Torsional impact response of a flat annular crack in a finite elastic cylinder
Authors: Shindo Y.
Published: October 2005

The torsional impact response of a flat annular crack in an elastic cylinder of finite radius is investigated in this study. Laplace and Hankel transforms are used to reduce the problem to the solution of a set of triple integral equations. These equations are solved by using an integral transform technique and the result is expressed in terms of a singular integral equation of the first kind. The singular stress field near the crack tip and the dynamic stress-intensity factor are determined. Numerical results on the dynamic stress-intensity factor are obtained to show the influence of inertia, geometry, and their interactions on the load transmission to the crack tip.
Intensity corrections in a random medium in the neighborhood of a caustic
Authors: Mazar R. , Beran M. J.
Published: October 2005

We apply the two-scale expansion developed previously to solve the equation governing the propagation of the coherence function in a random medium with a mean speed-of-sound profile. We obtain a formula for the vertical intensity distribution, resulting from an acoustic beam propagating in a statistically homogeneous, isotropic random medium with channel velocity profile. We use this formula to calculate the intensity distribution in the vicinity of a caustic in two limiting cases: weak scattering and strong scattering. We present a numerical example.
Coupling loss factors at a beam L-joint revisited
Authors: Sablik M. J.
Published: October 2005

Transmission coefficients and coupling loss factors are obtained for an L-joint between two beams when incident flexural waves are vibrating out of the plane of the L-joint. In the analysis, it is found that torsional waves develop at the L-joint and that flexural-to-torsional transmission can be more efficient than flexural-to-flexural transmission. Also treated are the cases of an incident torsional wave at the L-joint and an incident torsional wave at a butt joint. The expressions developed in this paper may be utilized in a statistical energy analysis of a beam network.
Investigation of interaural attenuation factors for frequencies above 8000 Hz
Authors: Rappaport B. Z. , Fausti S. A. , Schechter M. A. , Frey R. H.
Published: October 2005

Interaural attenuation values for frequencies from 8000 to 20 000 Hz were obtained from subjects with profound unilateral hearing loss. The values presented are specific to the Koss HV/1A earphone and cushion which is used as a transducer in our high-frequency testing system. Data are provided regarding the influence of nontest ears at frequencies above 8000 Hz in cases where ear asymmetry exists.
Perception of voice pitch waver over headphones and loudspeakers
Authors: Schmidt-Nielsen A. , Everett Stephanie S.
Published: October 2005

The perception of pitch waver in synthetic vowels was investigated. The waver was more easily detected when heard over a loudspeaker than over headphones. This effect seems to be related to the occurrence of amplitude variations as well as pitch variations in a live room environment.
LPC synthesis with simplified spectrum flattening of the excitation function
Authors: Gold B. , Tierney J.
Published: October 2005

Implementation of spectrum flattening of the excitation signal of an LPC (Linear Predictive Coding) vocoder is described. This modification yielded a small increase of intelligibility and a noticeable change in the quality of the perceived LPC speech.
Differences between read and spontaneous speech of deaf children
Authors: Smith Clarissa R.
Published: October 2005

Recordings were made of 20 congenitally deaf children, who produced spontaneous speech and, at a later session, read their own spontaneous utterances. Intelligibility scores and judgments of appropriateness of intonation, stress, timing, and sentence contour were obtained from experienced listeners. Read-spontaneous speech was more intelligible than spontaneous speech for 16 of the 20 children. Percentage of correct phoneme articulation was not significantly related to intelligibility.