bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nearfield beam patterns of exponentially shaded end-fire line arrays
Authors: Mellen Robert H. 
Published: October 2005

A contour integration method of calculating nearfield beam patterns of continuous, exponentially shaded, end-fire line arrays is presented. Only semi-infinite arrays are considered; however, the method can be applied to arrays of finite length.
Subject Classification: [43]30.85, [43]30.75; [43]25.35.
Acoustic reflex, loudness summation, and the critical band
Authors: Scharf Bertram 
Published: October 2005

As the bandwidth of a sound increases up to the critical bandwidth, loudness remains constant so long as overall intensity is constant. To keep loudness constant at wider bandwidths, intensity must be reduced. Similarly, the minimum intensity required to activate the acoustic reflex (AR) is constant as bandwidth is increased up to a critical value; beyond that value, intensity can be reduced. This critical width is much wider for the AR than for loudness summation. The literature and some new data show that the difference does not arise simply because the AR is measured at signal levels higher than those at which loudness summation is usually measured. Measured at the same high signal levels as needed to activate the AR, the critical band in loudness summation appears to be about two times wider than at lower levels; the ’’critical bandwidth’’ measured for the AR is some four to six times wider. Moreover, the AR shows a strong dependence on the number of components in a multitone complex, whereas loudness summation does not. Also, at very wide bandwidths the AR threshold shows a much larger decrease than would be predicted by the change in loudness. These differences suggest that the AR is not a direct corollary of loudness.
Subject Classification: [43]65.22, [43]65.50, [43]65.75.
Acoustic estimates of fish density and scattering function
Authors: Peterson Miles L. , Clay Clarence S. , Brandt Stephen B. 
Published: October 2005

The amplitude of a sonar echo from a fish depends upon the species and size of the fish, acoustic wavelength, aspect, position of the fish in the sonar beam, range and backscattering cross section. We simplify the problem to a single species and size of fish, vertically downward echo sounding, single aspect, and nonoverlapping echoes. After removal of attenuation due to range and absorption two random functions remain. The position of the fish in the sonar beam is random and the scattering cross section for each trail is random. We assume that the fish have a uniform density (number/m3) and calculate the probability density function (PDF) for insonification and reception. We assume that the PDF of the envelope of the echo (excluding the variability of insonification and reception) has a Rayleigh PDF. Assuming two PDF’s are independent, we calculate the PDF of the echo envelopes wE(e). wE(e) depends upon the beamwidth of the sonar and the mean backscattering cross section. The theoretical PDF has the same shape as the measured PDF of echoes from alewife in Lake Michigan. We use the fit of the PDF’s to estimate the backscattering cross section and fish density. This calibrates the echo-integration processing system. A profile of the density of alewife in Lake Michigan is shown.
Subject Classification: [43]30.40; [43]80.40.
Scattering matrix for elastic waves. I. Theory
Authors: Varatharajulu Vasundara , Pao Yih-Hsing 
Published: October 2005

A matrix theory is developed for investigating the scattering of elastic waves in solids by an obstacle of arbitrary shape. The scattering matrix which depends only on the shape and nature of the obstacle relates the scattered field to any type of harmonic incident field. Expressions are obtained for the elements of the scattering matrix in the form of surface integrals around the boundary of the obstacle, which can be evaluated numerically. Using the principle of reciprocity and the conservation of energy, the scattering matrix is shown to be symmetric and unitary. These properties are essential to assure the accuracy of numerical calculations. Both two- and three-dimensional problems are discussed, and the obstacle may be an elastic inclusion, a fluid inclusion, a cavity, or a rigid inclusion of arbitrary shape.
Subject Classification: [43]20.15, [43]20.30.
Matrix theory of elastic wave scattering
Authors: Waterman P. C. 
Published: October 2005

Upon invoking Huygen’s principle, matrix equations are obtained describing the scattering of waves by an obstacle of arbitrary shape immersed in an elastic medium. New relations are found connecting surface tractions with the divergence and curl of the displacement, and conservation laws are discussed. When mode conversion effects are arbitrarily suppressed by resetting appropriate matrix elements to zero, the equations reduce to a simultaneous description of acoustic and electromagnetic scattering by the obstacle at hand. Unification with acoustic/electromagnetics should provide useful guidelines in elasticity. Approximate numerical equality is shown to exist between certain of the scattering coefficients for hard and soft spheres. For penetrable spheres, explicit analytical results are found for the first time.
Subject Classification: [43]20.15, [43]20.30.
A near-wake model for the aerodynamic pressures exerted on singing trailing edges
Authors: Blake William K. 
Published: October 2005

Periodic vortex streets are formed in the wakes of blunted trailing edges on airfoils and struts. The pressures generated on the shedding struts by the vortices in these wakes are periodic in time with a frequency that is set by the shedding rate for the vortices. A simple analytical formulation is derived to relate wake-induced pressures to the characteristics of the wake near the edge. The chordwise distribution and magnitude of the pressure is shown as a function of the circulation of shed vortices, as well as the formation distance and the spacing of the vortices in the street. Predictions from the theory are compared to some recent measurements which were obtained in the wakes downstream of different trailing edges. These measurements were made at Reynolds numbers, based on trailing edge thickness, on the order of 104 to 105.
Subject Classification: [43]28.65; [43]50.55.
Vortex-shedding noise from oscillating cylinders
Authors: Burton T. E. , Blevins R. D. 
Published: October 2005

The theory of sound radiation from cylinders vibrating in resonance with vortex shedding is extended to consider the effects of vibration amplitude and mode shape. Farfield intensity and total radiated power are expressed as functions of given structural and flow parameters. Closed form solutions for intensity are obtained when cylinder vibration velocity is either much smaller than or comparable to mean flow velocity.
Subject Classification: [43]28.65, [43]40.26, [43]50.55.
The ac and dc components in lateral line microphonic potentials
Authors: Boston J. R. 
Published: October 2005

Measurements of the microphonic potential from the lateral line sensory organs of killifish (Fundulus heteroclitus) are presented in this report. The potential consists of a dc shift and a dominant oscillatory component at twice the frequency of the stimulus, and it grows with the square of the stimulus at low amplitudes. An electrical circuit model of the microphonic is developed, assuming a simple quadratic nonlinearity in the electrical response of an individual hair cell as suggested by Flock. The model allows investigation of variable conductive or variable capacitive effects in microphonic generation, and the results obtained from the model are compared to the observed properties of the microphonic potentials. It is concluded that hair cell microphonics appear to be generated by a process involving current flow through a variable conductance, although capacitive effects of the hair cell are important in determining the waveform of the microphonic and its behavior as a function of frequency. A discrepancy between the observed low-amplitude growth of the microphonic in killifish and the reported low-amplitude growth of the microphonic in other acoustico-lateralis preparations is also discussed.
Subject Classification: [43]65.28, [43]65.20, [43]65.40.
Growth of loudness at 1000 and 3000 Hz
Authors: Hellman Rhona P. 
Published: October 2005

Loudness growth at 1000 and 3000 Hz was measured directly by magnitude estimation and production, and indirectly by loudness matches between tone and wide-band noise and by interfrequency matching. The outcome of the three series of experiments does not reveal any systematic difference in shape of the loudness curves at 1000 and 3000 Hz. To a first approximation, above about 30 dB SL the loudness functions at 1000 and 3000 Hz are power functions of sound pressure with an exponent close to the accepted ISO standard of 0.60 (0.30 re sound intensity). Below 30 dB SL both loudness curves become progressively steeper than a simple power function and approach the same limiting slope, re sound intensity, of unity. Consistent with Steven’s calculation system [J. Acoust. Soc. Am. 51, 575–601 (1972)], the data also show that loudness equality is achieved when a 3000-Hz tone is about 8 dB below the SPL of a tone at 1000 Hz.
Subject Classification: [43]65.50, [43]65.75.
Some vocal distinctive features used by gelada monkeys
Authors: Richman Bruce 
Published: October 2005

Recordings have been made of gelada monkeys freely vocalizing during normal social interchanges in captivity. Spectrographic analyses and perceptual evaluations of the recordings suggest that these primates produce a greater range of vocal distinctive contrasts than have been observed previously. In particular, evidence is presented which suggests that gelada monkeys are capable of producing three distinctive voice qualities, a wide range of vowel qualities, and a set of consonants that differ in manner of articulation (glides, a fricative, plosives, nasals) and in place of articulation (labial, postdental, velar).
Subject Classification: [43]70.40, [43]70.20; [43]80.50.
Measurement of acoustoelastic and third-order elastic constants for rail steel
Authors: Egle D. M. , Bray D. E. 
Published: October 2005

Measurements of the stress-induced changes in ultrasonic wave speeds in steels typically used in railroad rails are presented. All of the five possible relative changes in wave speeds for a uniaxial state of stress have been determined and agree, to within the limits of accuracy of the measurement, with the second-order theory of Hughes and Kelly. The third-order elastic constants are calculated from the acoustoelastic data.
Subject Classification: [43]85.20, [43]85.22, [43]35.26.
Low-frequency coherence transverse to the direction of propagation
Authors: Fitzgerald R. M. , Guthrie A. N. , Shaffer J. D. 
Published: October 2005

Experimental evidence is presented which indicates that the coherence of 10 Hz signals in the deep ocean is sufficient to form a passive-transverse synthetic aperture in excess of 1600 m.
Subject Classification: [43]30.20.
Prediction of noise distribution in various enclosures from free-field measurements
Authors: Galaitsis Anthony G. , Patterson William N. 
Published: October 2005

The image theory method is used to predict sound pressure levels generated by an acoustic source of known strength in regular rooms, tunnels, and flat rooms. For regular rooms, the results are identical to those of the well-established diffuse field theory. For tunnels and flat rooms, the predictions are verified by direct measurements taken in underground mines.
Subject Classification: [43]55.20, [43]55.55.
Modified phase integral approximation for a more rigorous ray tracing technique
Authors: Floyd Edward R. 
Published: October 2005

The phase integral approximation is modified to describe wave propagation in three dimensions without any singularities at classical turning points. For stratified media a rigorous ray tracing scheme is derived. Stratified media are shown in general to induce dispersion. The connections to both the normal mode and filter theory methods are discussed. The effects of oceanic surface thermoclines upon rigorous ray tracing are shown to be frequency dependent.
Subject Classification: [43]30.20; [43]20.15.
Nonspectral pitch
Authors: Burns Edward M. , Viemeister Neal F. 
Published: October 2005

The spectrum of amplitude-modulated wide-band noise is invariant with changes in modulation frequency, and consequently such waveforms cannot convey melodic information by spectral changes. The results of several experiments indicate, however, that sinusoidally amplitude-modulated wide-band noise does have pitchlike properties. Simple melodies can be identified when the ’’notes’’ correspond to different modulation frequencies. More importantly, musically trained observers can immediately recognize melodic muscial intervals composed of such waveforms. The pitchlike properties of modulated noise are maintained when the modulated noise is bandpass filtered and when an unmodulated band-reject masker is added to the bandpass noise. Presumably the perception of pitch elicited by modulated noise is based upon temporal information in the envelope of the waveform. This ’’temporal pitch’’ is less salient than the pitch elicited by pure tones. Also, temporal pitch can be elicited only over a restricted range of modulation frequencies. The upper limit (approximately 850–1000 Hz) appears to reflect the inability of the auditory system to follow rapid temporal changes.
Subject Classification: [43]65.54, [43]65.75.
Response to ’’Comments on ’Diffuse sound reflection by maximum length sequences’ ’’ [J. Acoust. Soc. Am. 60,268–268(1976)]
Authors: Schroeder M. R. , Gerlach R. 
Published: October 2005

Complementary maximum length sequences, recently proposed by Moharir,1 do not give as good sound diffusors as those originally proposed by Schroeder.2 A rule for constructing two-dimensional sequences is given.
Subject Classification: [43]55.20, [43]55.40.
Multipath scintillation spectra
Authors: Adams Stanley L. 
Published: October 2005

In a recent paper by Dyson, Munk, and Zetler [’’Interpretation of multipath scintillations Eleuthera to Bermuda in terms of internal waves and tides,’’ J. Acoust. Soc. Am. 59, 1121–1133 (1976)], approximate expressions were derived for the spectrum of the phase and intensity scintillations of a sinusoidal signal after propagation through a certain random multipath channel. From the multipath structure specified in that paper, exact results are obtained for the phase-derivative fluctuation spectrum. This expression can be easily evaluated and compared to the approximation. In addition, amplitude and square-amplitude fluctuation spectra are derived.
Subject Classification: [43]30.20, [43]30.30.
Use of a nearfield array for acoustic backscattering cross-section measurments
Authors: Fiorito Ralph , Madigosky Walter 
Published: October 2005

It is theoretically demonstrated that a circular piston operating at high frequency can be used as a nearfield array to receive and measure farfield backscattering (sonar) cross sections. Experiments are described which use a 4.75-in.-diam piston operating at 15 MHz as a transmitter/receiver within the nearfield zones of the piston and scattering object. Results obtained are in good agreement with those theoretically predicted by finite-beam insonification-scattering theory. Comparison of scaled-model ship measurements with farfield values shows reasonable agreement as well.
Subject Classification: [43]30.82; [43]30.40.
Turbulent-boundary-layer noise in the interior of aircraft operating at varying altitudes
Authors: Bray Don E. 
Published: October 2005

The effect of altitude on the interior noise level of commerical aircraft has been studied. Changes in noise levels are shown to be very closely related to the square of the local air density. Data collected on regularly scheduled flights on the C scale and the A scale are generally seen to be in very good agreement with the predicted changes.
Subject Classification: [43]50.50, [43]50.55; [43]28.65.
Influence of subarachnoid structures on transmeningeal ultrasonic propagation
Authors: Johnston R. L. , Dunn F. 
Published: October 2005

The previously observed frequency dependence of the ultrasonic threshold dose, for production of irreversible lesions in mammalian brain, is ascribed to the brain meninges. The collagenous trabeculae of the subarachnoid space, interposed between the arachnoid and the pia mater, are considered responsible by virtue of the increased elastic moduli associated with their structural supporting role. A plane three media model provides acoustical parameters of these anatomic structures. The method provides the frequency-independent lesion-threshold function It1/2=200 W/cm2 sec−1/2.
Subject Classification: [43]80.40.[43]80.20
Rayleigh disk in an aligned nematic liquid crystal
Authors: Hayes C. F. 
Published: October 2005

If a Rayleigh disk were suspended in an aligned nematic liquid crystal there would be two torques acting on the disk: one due to the acoustic wave and the other an elastic torque due to the liquid crystal. For a disk of radius 50 μm an acoustic intensity typically of ∠1 mW/cm2 would orient the disk at 45° to the direction of the incident wave if the acoustic wave is directed perpendicular to the optic axis of the liquid crystal. The applicability to detection of acoustic fields is noted.
Subject Classification: [43]85.35.
Spherical-wave reflection from a boundary of reactive impedance using a modification of Cagniard’s method
Authors: Donato R. J. 
Published: October 2005

The solution using Cagniard’s method for the reflection of a spherical wave from a locally reacting plane boundary is compared to that using the steepest descents method. The contribution from the presence of a pole is less arbitrary using this method and the transition from the pole to the no pole case is shown to be gradual. A further solution in the time domain for an incident time impluse function is also derived.
Subject Classification: [43]20.15, [43]20.30; [43]28.40.
Brainstem auditory evoked responses in man. I. Effect of stimulus rise–fall time and duration
Authors: Hecox Kurt , Squires Nancy , Galambos Robert 
Published: October 2005

Short latency (under 10 msec) evoked responses elicited by bursts of white noise were recorded from the scalp of human subjects. Response alterations produced by changes in the noise-burst duration (on time), interburst interval (off time), and onset and offset shapes are reported and evaluated. The latency of the most prominent response component, wave V, was markedly delayed with increases in stimulus rise time but was unaffected by changes in fall time. Increase in stimulus duration and therefore loudness resulted in a systematic increse in latency, probably due to response recovery processes, as this effect was eliminated with increases in stimulus off time. The amplitude of wave V was insensitive to changes in signal rise and fall times, while increasing signal on time produced smaller amplitude responses only for sufficiently short off times. It is concluded that wave V of the human auditory brainstem-evoked response is solely an onset response.
Subject Classification :[43]65.59.[43].65.75.
Graphical method for reflection of plane waves in a micropolar half space
Authors: Ozgur Dincer , Cakmak Ahmet S. 
Published: October 2005

Analysis of reflection of plane waves from a flat boundary in a micropolar half space poses tedious calculations. In this paper, utilizing the concept of slowness surfaces, a simple and efficient method is proposed as an alternative to the previous analytical methods. Critical angles of incidence, the nature of the reflected body, and boundary waves corresponding to the incident longitudinal displacement and coupled transverse displacement microtational waves are studied.
Subject Classification: [43]20.15, [43]20.30.
Angle-depth diagram for use in underwater acoustics
Authors: Flatté Stanley M. 
Published: October 2005

The value of a diagram in which the angle of an acoustic ray is plotted versus its depth is explored. The concept of source line in angle-depth space is developed. Characteristics of different sound channels, reflection, multipath, caustics, and the analysis of obstacles such as seamounts are described within the context of the diagram. The application of Liouville’s theorem is discussed.
Subject Classification: [43]30.20; [43]20.20.
Image profiles in schlieren observations of acoustic wave fronts
Authors: Bucaro J. A. , Flax L. , Dardy H. D. , Moore W. E. 
Published: October 2005

Image-intensity functions have been calculated for acousto-optic phase-resolved schlieren in the phase grating (Raman–Nath) diffraction limit. The calculation applies to the case where a circular stop is used. Any number of diffraction orders may be stopped. The results are programmed into a laboratory GT-44/PDP-11 real-time graphic system and compared to experimental observations. The latter include TV monitoring of both the diffraction orders and the image distribution and photomultiplier-pinhole recording of the image-intensity distribution. It appears that phase resolution will permit quantitative pressure level determinations. The results aid significantly in interpreting phase-resolved schlieren observations from radiation and scattering mechanisms.
Subject Classification: [43]35.65.
Method to convolve sound-level distributions for prediction of community sound levels
Authors: Kessler Frederick M. , Gottlieb Peter 
Published: October 2005

Predicting community noise levels requires the addition of background ambient sound levels and the source’s contribution to ambient sound levels. Baseline data are obtained, from community sound surveys, in the form of histograms and cumulative distributions. Source (for example, a construction site) sound level data are also obtained as histograms and cumulative distributions. The problem of combining the two distributions is made somewhat difficult by the logarithmic nature of the physical variable. The prediction is accomplished by the mathematical convolution of the variables representing baseline and the source. Since the data are provided as histograms rather than as continuous probability density functions, it is convenient to decompose the density functions into a sequence of Dirac delta functions. The result can be programmed for a rapid and efficient computation. Results are provided for the combination of various construction site sound level distributions (e.g., normal and bimodal) with community background ambient sound. Data are shown of the effect on community noise of a source contribution which is attenuated by distance.
Subject Classification: [43]50.75.
Auditory-nerve-fiber bandwidths and critical bandwidths in the cat
Authors: Pickles J. O. , Comis S. D. 
Published: October 2005

The effective bandwidths of cat auditory-nerve fibers were estimated electrophysiologically from the masked thresholds of tones at the nerve fibers’ characteristic frequency. The masking noise was of variable bandwidth but constant total power and was geometrically centered on the characteristic frequency. It was presented at an intensity which, for the narrowest masker bandwidth used, raised the tone threshold by about 20 dB. The point at which the masked tone threshold began to decline as the masker bandwidth was increased provided an estimate of the fiber’s effective bandwidth. A similar method had been used in earlier psychophysical estimates of the cat’s critical band. The auditory-nerve-fiber bandwidths were on average 6 dB less than the critical bandwidth at the same frequency. Two of the cats had been tested both psychophysically and electrophysiologically; in these cats the difference was 6.8 dB. Most fibers, moreover, had critical ratios less than that observed psychophysically. The results suggest that the critical band is not a simple correlate of the tuning curves of auditory-nerve fibers.
Subject Classification: [43]65.42, [43]65.58.