bluuebunny/crossref_metadata_2025 huggingface dataset:
Invariant Gauss−Gauss detection in colored noise
Authors: Beckham L. W. , Austin M. E.
Published: October 2005

The purpose of this paper is to present a method of solving the Gaussian signal in Gaussian noise detection problem when the additive noise influence is not white and the signal and noise strength parameters are unknown to the receiver. This problem has been solved for a finite−dimensional receiver when the channel noise is white. By using a ’’simultaneous diagonalization of covariance matrices,’’ the problem of colored noise can be transformed into the previously considered problem. Furthermore, when the finite−dimensional representation does not apply, a ’’simultaneous orthogonal expansion of covariance kernels’’ will prove to be the medium through which the general problem can be transformed into a white−noise problem. For the restricted case when the finite−dimensional case does apply it will be shown that the same expansion leads to a receiver of the type previously proposed with minor modifications.

Subject Classification: 60.XX.
Underwater frequency discrimination in the bottlenosed dolphin (1–140 kHz) and the human (1–8 kHz)
Authors: Thompson Roger K. R. , Herman Louis M.
Published: October 2005

Frequency difference limens (DLs) were obtained for frequencies (F) from 1 to 140 kHz for the bottlenosed dolphin, Tursiops truncatus (Montagu), and from 1 to 8 kHz for two human subjects tested underwater. Discriminations were required between constant-frequency (pure-tone) signals and frequency-modulated signals, using a successive discrimination procedure. Relative DLs (DL/F) for the dolphin generally ranged from 0.002 to 0.004 between 2 and 53 kHz, and never exceeded 0.008 through to 130 kHz; at 1 and 140 kHz, relative DLs increased to 0.014. No responses were obtainable at 150 kHz. These findings demonstrate excellent frequency discrimination throughout the audible spectrum (above 1 kHz) of Tursiops and support electrophysiological evidence of highly sensitive frequency detection mechanisms. Results for the humans showed smaller DLs than the dolphin at 1 kHz, approximately equal DLs at 2 kHz, and progressively larger DLs at 4 and 8 kHz. The human underwater thresholds were generally consistent with typical human in-air measurements of frequency DL.

Subject Classification: 65.54, 65.22; 80.50.
Nonlinear propagation of a wave packet in a hard-walled circular duct
Authors: Nayfeh Ali Hasan
Published: October 2005

The method of multiple scales is used to derive a nonlinear Schrödinger equation for the temporal and spatial modulation of the amplitudes and the phases of waves propagating in a hard-walled circular duct. This equation is used to show that monochromatic waves are stable and to determine the amplitude dependance of the cutoff frequencies.

Subject Classification: 25.20; 20.45.
Nonlinear oscillations of gas bubbles in liquids. Transient solutions and the connection between subharmonic signal and cavitation
Authors: Prosperetti Andrea
Published: October 2005

The transient nonlinear oscillations of a spherical gas bubble in an incompressible, viscous liquid subject to the action of a sound field are investigated by means of an asymptotic method. Approximate analytical solutions are presented for the frequency regions of the fundamental resonance, the first and second subharmonic, and the first and second harmonic. Based on the results of this investigation, a new hypothesis to explain the connection between subharmonic signal and cavitation is put forward. It is suggested that bubbles emitting the subharmonic signal act primarily as monitors of cavitation events, and are smaller than resonance size. Finally, the free oscillations of the bubble are briefly considered.

Subject Classification: 35.10.
Effect of atmospheric absorption on the acoustic power spectrum of thunder
Authors: Bass Henry E. , Losey Robert E.
Published: October 2005

Recordings of six thunder events have been analyzed in 1/3-octave bands over the frequency range 50–500 Hz to determine the relative acoustic power spectrum. The received power spectra have been corrected for propagation loss due to viscosity, thermal conductivity, and molecular relaxation. The correction, which is strongly dependent upon atmospheric conditions that were not measured, yields spectra so nearly identical to suggest that the six thunder events have identical spectra (within 5 dB) in the frequency range considered.

Subject Classification: 28.20; 20.35.
Scaling loudness, noisiness, and annoyance of aircraft noise
Authors: Berglund Birgitta , Berglund Ulf , Lindvall Thomas
Published: October 2005

The capacity of man to differentiate and scale aircraft noise with regard to three psychological attributes frequently encountered in social survey research on ambient noise was tested. Calibrated scales for the attributes evolved from the two-step psychological scaling procedure employed. It was demonstrated that observers in carefully designed laboratory situations are able to use and produce scales of loudness, noisiness, and annoyance for aircraft noise. The relationships between the attributes were satisfactorily described by linear functions. In general, aircraft noise was judged to be more annoying than noisy and more noisy than loud. For all three attributes, the psychophysical relationships were best described by power functions with dB(A)max as the physical measure (exponents 0.21–0.24).

Subject Classification: 65.50, 65.75.
Dispersion of flexural elastic waves in honeycomb sandwich panels
Authors: Thompson R. B. , Alers G. A. , Thompson D. O. , Tennison M. A.
Published: October 2005

The phase velocity of flexural waves traveling along a 1-in.-thick honeycomb sandwich panel has been experimentally determined from 170 Hz to 50 kHz by using three techniques: measurement of resonant frequencies of beam-shaped samples in forced vibration, measurement of nodal spacing in standing wave patterns on beam-shaped samples, and measurement of the change in time delay of a particular phase feature of a wave packet as a function of propagation distance on large plate samples. The experimentally determined velocities ranged between 2.2×104 cm/sec at 170 Hz to 1.18×105 cm/sec at 40 kHz. This dispersion arises primarily from the geometrical effect of the finite thickness of the panel and agrees well with two theoretical models; a plate theory and an elasticity theory, each of which treats the core as a continuum. Above 40 kHz, the predictions of the two models differ greatly for the particular panel geometry studied. The experimental phenomena become more complex and appear to agree with neither model, quite possibly due to the neglect of the periodicity of the core. A brief description of these results is given.

Subject Classification: 40.24; 35.26.
Experimental investigation of subharmonic generation in an acoustic interferometer
Authors: Yen Nai-chyuan
Published: October 2005

The author has shown previously [J. Acoust. Soc. Am. 49, 119(A) (1971)] that the nonlinear properties of the medium can induce coupling among the modes in a multiresonant system and that the threshold and steady-state response of subharmonic components can be predicted. In the present work, coupling induced by nonlinear properties is further illustrated by observing the subharmonic generation phenomenon in an acoustic interferometer. The experimental investigation was conducted with a 1.5-MHz driving signal and used filtered and degassed water as the medium. Data concerned with the actual modes of the interferometer, the loss factor associated with the subharmonic modes, and the threshold of subharmonic generation, with length of the interferometer and the driving frequency varying, are consistent with the analytic results, provided that cavitation is carefully avoided.

Subject Classification: 25.15, 25.20; 30.75.
Optimum signal processing for passive sonar range and bearing estimation
Authors: Hahn William Robert
Published: October 2005

Optimum signal processing for passive sonar target range and bearing estimation is discussed for the case where the sonar array consists of an M-element linear array of hydrophone point detectors whole individual outputs are corrupted by sensor-to-sensor-independent self-noises of arbitrary power spectra. By comparing the measurement error covariance matrix to the Cramér–Rao matrix bound the system performance, relative to the theoretical optimum, is determined. Further, the Cramér–Rao bound is used to determine an optimum signal processor. The optimum processor is configured as a set of M (M-1)/2 cross-correlator delay estimators (one for each hydrophone pair), followed by a Gauss–Markov estimation of the array delay vector (target steering vector), which in turn is followed by a linear weighting of the estimated delay vector elements to determine a bearing estimate and a range estimate. The processor is shown to have the Cramér–Rao matrix bound for its measurement error covariance matrix.

Subject Classification: 60.30; 30.82.
Motor vehicle noise spectra, their characteristics and dependence upon operating parameters
Authors: Hillquist Ralph K. , Scott William N.
Published: October 2005

Data obtained from many sources are used to describe the physical characteristics of traffic noise, its individual components, and some of the means for reducing motor vehicle noise. The noise characteristics of trucks, automobiles, and motorcycles are discussed separately. The composite of all motor vehicle noise (traffic noise) is described in terms of the operating parameters of interest, including vehicle speed, engine speed, throttle position, engine type, tire-tread type, and road surface smoothness.

Subject Classification: 10.60; 50.25, 50.50.
Noise isolation in an infrasonic hydrophone calibrator
Authors: Bobber R. J.
Published: October 2005

Suspending a heavy hydrophone calibrator from pneumatic springs produced an order of magnitude improvment in isolation of the calibrator from strong sources of noise in the 5- to 10-Hz frequency range over that provided by a cork-nested foundation.

Subject Classification: 85.62; 30.85; 40.75; 28.30.
Free-field method for sound-attenuation measurement
Authors: Hruska Gale R. , Koidan Walter
Published: October 2005

A free-field method is described for measuring the attenuation of sound at ultrasonic frequencies. It makes use of the systematic deviation from the inverse square law caused by attenuation when a sound receiver is drawn away from a sound source. Measurements of attenuation from 20 to 100 kHz, made in air in a small anechoic chamber under ambient environmental conditions, were in good agreement with theoretical calculations. The sum of the distances between the acoustic centers of the transducers and the vibrating elements is obtained as a by-product of the procedure.

Subject Classification: 35.20; 20.35.
Some extensions of Babinet’s principle
Authors: Senior T. B. A.
Published: October 2005

Two different extensions of Babinet’s principle are discussed. In the first of these, an aperture in a soft or hard screen is covered with a membrane characterized by a jump discontinuity in either the normal component of the fluid velocity or the pressure, and the complementary problem is then a membrane in isolation. In the second, a boundary condition is imposed in the aperture, the solution for which can be obtained from the solution for the complementary disk.

Subject Classification: 20.30.
Short-wavelength acoustic backscattering by a prolate spheroid
Authors: Lauchle Gerald C.
Published: October 2005

The backscattering of a plane acoustic wave from a rigid prolate spheroid of large fineness ratio (length-to-diameter ratio of 22) is investigated analytically. The backscattering cross section is computed with the use of large argument asymptotic expansions of spheroidal wave functions. It is shown that in the short-wavelength limit, a spheroid backscatters in the axial direction nearly the same mean energy as a sphere whose radius equals the radius of curvature of the spheroid at the pole end. When the spheroid is positioned broadside to the incident wave, the backscattered mean energy is found to correspond to that backscattered from a sphere of diameter equal to the length of the spheroid.

Subject Classification; 20.15, 20.30.
Cross-correlation methods for studying near- and farfield noise characteristics of flow–surface interactions
Authors: Pan Y. S.
Published: October 2005

Systematic methods based on cross-correlation techniques are presented for experimental studies of near- and farfield noise characteristics in airflow–surface interaction problems. Analyses show that, in near- and farfields, the noise characteristics due to the surface contribution of fluctuating pressures and velocities and due to the volume contribution of the turbulence in the flow can be determined separately. Both farfield noise intensities and nearfield acoustic energy fluxes can be expressed in terms of appropriate cross correlations. These correlations can be obtained by making microphone measurements in the farfield, in the nearfield, and on the surface. Examples of the applications to the noise field generated by impinging jets, by surface blowing jets, and by turbulent flow over trailing edges are presented. Advantages of the present method over conventional methods are also discussed.

Subject Classification: 28.65; 50.25, 50.30, 50.55.
Monaural localization of low-pass noise bands in the horizontal plane
Authors: Belendiuk Krystyna , Butler Robert A.
Published: October 2005

Monaural localization of low-pass noise positioned in the horizontal plane on the side of the unoccluded ear was investigated. Listeners showed no localizing ability until the upper cutoff frequency of the noise was advanced to 5.0 kHz. Performance proficiency increased progressively with the inclusion of still higher audio frequencies. Consonant with the behavioral data were the results of sound spectrum measurements performed on a head–pinna model. The spectral composition of a broad-band noise positioned at various azimuthal positions became clearly distinguishable, one from another, only at the higher frequencies.

Subject Classification: 65.62, 65.75, 65.54.
Data requirements for the mapping of ultrasonic fields with conventional light diffraction
Authors: Berlinghieri Joel C. , Cook Bill D.
Published: October 2005

A procedure has been proposed by Cook [J. Acoust. Soc. Am. 53, 330(A) (1972)] through which a cross-sectional mapping of a progressive sound beam could be obtained by conventional light diffraction. This technique requires that a series of optical diffraction measurements be taken laterally across the field, for a large number of rotations about the sound field’s major axis. Since the number of measurements could become excessive, and investigation of the data requirements of this technique has been performed. Computer-generated data were calculated of the integrated optical effect (both magnitude and phase) produced by the pressure field of a circular plane piston in an infinite rigid baffle. From these data a cross-sectional map was obtained using an effective two-dimensional Fourier transform, as well as the two-dimensional fast Fourier transform algorithm. The cross-sectional mapping was evaluated at different axial positions, using one set of data obtained by varying the data set and comparing the results to those obtained from the diffraction integral. The data requirements were found not to be excessive.

Subject Classification: 35.65.
Perturbation solution of the Navier–Stokes equations and its relation to the Lighthill–Curle solution of aerodynamic sound
Authors: Pan Y. S.
Published: October 2005

The Lighthill–Curle solution of sound generated aerodynamically is examined by a perturbation approach. Based on the method of matched asymptotic expansions, the full Navier–Stokes equations are expanded for a small Mach number. To the first order, the nearfield is generally nonisentropic. The pressure field (pseudosound) is generated by the incompressible Reynolds stresses in the turbulent flow and the velocity, pressure perturbation, and their derivatives on the boundaries. In the farfield, the acoustic field is obtained by matching the nearfield and determined by the first-order sound sources. A uniformly valid first-order solution for the pressure field is obtained. The solution shows that this kind of aerodynamic sound generation does not depend on the viscous, thermal, and entropy effects in the adiabatic flow nor on the shear stress on a rigid smooth boundary. Comparisons with the Lighthill–Curle solution confirm some approximations used in current farfield aerodynamic noise studies.

Subject Classification: 28.65; 30.65; 50.55.
Probe-signal investigation of uncertain-frequency detection
Authors: Macmillan Neil A. , Schwartz Madelyn
Published: October 2005

Observers in a 2IFC detection task were instructed to listen for ’’primary’’ tones with one of two frequencies, in the presence of a broad-band background noise. On a small proportion of trials, probe tones of other frequencies were presented instead, following the procedure of Greenberg and Larkin [J. Acoust. Soc. Am. 44, 1513–1523 (1968)]. The function relating percent correct to signal frequency may be interpreted as an average internal filter characteristic. All six observers responded correctly on 70%–90% of trials on which primary signals were presented; performance on probe trials was poorer, falling to chance for probe frequencies sufficiently above the higher primary, sufficiently below the lower primary, and for some probes between the two primaries. The widths of the listening bands around the primaries were found to be similar to the widths estimated from one-primary control conditions. Examination of the sequential data suggests that, while the pattern of sensitivity changes from trial to trial, a model postulating a single filter shifting from one primary to the other is not adequate. Other models of uncertain-frequency detection are discussed.

Subject Classification: 65.35, 65.75, 65.58.
Interaural attenuation versus frequency for guinea pig and chinchilla CM response
Authors: Teas Donald C. , Nielsen Donald W.
Published: October 2005

Interaural attenuation was estimated for the guinea pig and the chinchilla by determining isopotential curves for the cochlear microphonic (CM) response produced by contralateral and by ipsilateral stimulation at frequencies from 300 Hz to 14.3 kHz. Intracochlear electrodes were used to record the CM from the basal turn. For ipsilateral stimulation, bulla-sealed to bulla-open sound pressure ratios showed effects similar to those reported by other investigators: 10–12-dB loss for chinchilla and 20–22-dB loss for the guinea pig for the bulla-sealed condition. The variability of the sound pressure measures, considered across animals, was larger in chinchillas than in guinea pigs, and the variance was greatest at frequencies near those at which the external auditory canals and bulla cavities show resonant peaks. There appears to be additional low-frequency resonances associated with contralateral stimulation for the closed bulla in the chinchilla, largest at 1.1 kHz for frequencies sampled in this report. The interaural attenuation for the chinchilla is largest at low frequencies and is at a minimum of about 34 dB for the open bulla, near 3.0 kHz; in the guinea pig, the minimum interaural attenuation occurs for the closed bulla, about 44 dB at 300 Hz.

Subject Classification: 65.42, 65.40, 65.75.
Speed of sound in water: A simple equation for realistic parameters
Authors: Medwin Herman
Published: October 2005

A simple equation is presented for the dependence of sound speed on temperature, salinity, and depth of water. The comparison with Del Grosso’s NRL II shows discrepancies of the order of tenths of m/sec for realistic values of the parameters.

Subject Classification: 30.25.
Range-dependent normal modes in underwater sound propagation: Application to the wedge-shaped ocean
Authors: Graves R. D. , Nagl Anton , Überall H. , Zarur G. L.
Published: October 2005

We use the adiabatic range variation method of Pierce and Milder to perform an approximate separation into normal modes of the wave equation for the problem of underwater sound propagation in an almost-stratified under-ocean channel with gradual range dependence of medium and boundaries. Our solution is illustrated by an application to the isovelocity ocean wedge with rigid ocean floor, and compared with the exact solution of Bradley and Hudimac. Even when mode coupling is neglected, good agreement is obtained for moderately large wedge angles.

Subject Classification: 30.20; 20.15, 20.40.
Linear estimation of nonstationary signals
Authors: Liporace Louis A.
Published: October 2005

The efficacy of linear prediction for speech analysis depends upon the degree to which the speech signal is stationary within an analysis interval. For this reason the speech signal is usually divided into small intervals during each of which the signal is assumed to be stationary. The formulation described in this paper is aimed at accomodating the nonstationarity more automatically by allowing the linear estimate of the speech signal to be time varying.

Subject Classification: 70.40, 70.65.
Equivalent circuit of a ceramic ring transducer operated in the dipole mode
Authors: Gordon Robert S. , Parad Leonard , Butler John L.
Published: October 2005

An equivalent circuit for a piezoelectric ring transducer excited in its dipole mode and its remaining odd-order curcumferential extensional modes is derived. The analysis is accomplished by expressing the applied electric field excitation by a Fourier series and then combining solutions appropriately. The equivalent network presented here has a voltage–current terminal pair and a force–velocity terminal pair to each Fourier component which yield the transducer performance for the dipole and higher-order modes.

Subject Classification: 85.52; 40.85.
Observation of acoustic layering and internal waves with a narrow-beam 87.5-kHz echo sounder
Authors: Fisher F. H. , Squier E. D.
Published: October 2005

Multiple thin layers have been observed from depths of 154 to 470 m with a narrow-beam (±0.5° at 3 dB down) high resolution (0.6-msec pulse) mounted on the bottom of FLIP. Layer reflection coefficients vary between −90 and −100 dB. The layers varied in depth sinusoidally about 5 m with a 22-min period, indicating internal wave motion. Echo returns from the bottom at 770 fathoms indicated a reflection coefficient of −34 dB, in good agreement with earlier work at 75 kHz by Bezdek.

Subject Classification: 30.20, 30.82.
Nonlinear effects of initial bending on the vibrations of crystal plates
Authors: Lee P. C. Y. , Wang Y. S. , Markenscoff X.
Published: October 2005

The changes in the resonance frequencies of circular crystal plates subject to initial bending stresses are studied. The plate is flexed as a cantilever clamped near the edge and stressed by a transverse, concentrated force applied at a point diametrically opposite the support. A system of plate equations which takes into account the nonlinear effects due to the large, initial deflection and to the third-order elastic stiffness coefficients in the stress–strain relations is employed. In obtaining the initial fields caused by bending, strain components are assumed to be small, but large gradient of plate deflection and large rotations of the plate element about x1 and x3 axes are permissble by retaining their quadratic terms in the strain-displacement relations. The changes of resonance frequencies of fundamental thickness-shear vibrations are calculated for rotated Y cuts of quartz. The calculated frequency changes are compared with experimental values as a function of the force position, the azimuth angle ψ, and also as a function of the magnitude of thr force P.

Subject Classification :[43]40.24.
Gaussian–Laguerre/Hermite formulation for the nearfield of an ultrasonic transducer
Authors: Cook B. D. , Arnoult W. J.
Published: October 2005

The orthonormal sets of functions known as Gaussian–Laguerre and Gaussian–Hermite functions (G–L/H) have previously been used in quantum mechanics, electromagnetic waves and laser optics. These functions satisfy a modified wave equation, valid under certain restrictive conditions appropriate to slowly diverging sound fields. The nearfield of an ultrasonic transducer can be expressed as a linear combination of modes, each described by a G–L/H function. Each mode has a slightly different phase velocity in the nearfield but has the same spreading nature and phase velocity in the farfield. Using this formulation, the transition from nearfield to farfield is readily explained.

Subject Classification: [43]20.55; [43]35.80; [43]20.15.
Dichotic ’’masking’’ of voice onset time
Authors: Repp Bruno H.
Published: October 2005

When CV targets are presented to one ear and isolated vowel masks to the other ear, the perception of the voicing feature of the target is biased by the temporal relationship between target and mask which acts like a ’’pseudo-voice onset time’’ and competes with the actual voice onset time of the target as a voicing cue. The effect is especially strong when there is high a priori uncertainty about the voicing category of the target, and it is more pronounced when the masking vowel lags behind than when it leads in time. The bias is strongest when the masking vowel is the same as the vowel of the target, but is present with a phonetically different vowel mask as well. There tends to be a right-ear advantage which is strongest when the masking vowel leads in time. The fundamental frequency at masking vowel onset has an additional influence: The lower it is, the stronger is the tendency to identify the target as voiced. Two simple additive models of the vowel ’’masking’’ effect are rejected. The relative complexity of the effect suggests dichotic interaction at the phonetic (precategorical) level. The present experiments demonstrate that a temporal relationship, voice onset time, may be ’’masked’’ by another temporal relationship, the voice onset time across ears.

Subject Classification: [43]70.30; [43]65.48, [43]65.58, [43]65.62.
Phase effect of an input f2−f1 tone on the level of the 2f1−f2 combination tone
Authors: Crane Hewitt D. , Bell Donald W.
Published: October 2005

A model of hair cell excitation that involves mechanical impact between the hair cells and the tectorial membrane has been proposed by Crane [J. Acoust. Soc. Am. 40, 1147–1154 (1966); J. Acoust. Soc. Am. 51, 508–514 (1972)]. The model predicts that if the impact is unilateral, biasing of the basilar membrane toward or away from the tectorial membrane will significantly affect the generation of nonlinear combination tones. An f2−f1 envelope tone synchronized with the f1 and f2 primaries was used to achieve such biasing. The experiment reported here investigates the effect of the phase of the f2−f1 tone on the prominence of the beating of a 2f1−f2 combination tone (generated by input primaries f1 and f2) and a probe tone that differs in frequency by a few hertz from the frequency of the combination tone. The input thus consists of four explicit tones: f1, f2, f2−f1, and (2f1−f2)+δ. It was found that the f2−f1 tone can have a large effect on the level of the 2f1−f2 combination tone. The phases of the f2−f1 tone that lead to a maximum and minimum level of combination tone are approximately 180° apart, and there can be almost total discrimination between those two phase conditions.

Subject Classification: [43]65.56, [43] 65.28, [43]65.60.
Critical angle for reflection at a liquid–solid interface in single crystals
Authors: Henneke Edmund G. , Jones Gerald L.
Published: October 2005

Recent investigations have utilized the measurement of the critical angle for reflection from a liquid-solid interface for determination of the elastic constants of the solid. For anisotropic media, this technique is appropriate only for certain special cases of the incident plane and reflecting surface. We discuss here the general condition for the critical angel in anisotropic media and show that for some planes in quartz, major errors may arise if one employs the usual statement of Snell’s law for definition of the critical angle.

Subject Classification: [43]20.30; [43]35.26.
Further calculation on Rayleigh wave diffraction by elastic wedges
Authors: Yoneyama Tsukasa , Nishida Shilgeo
Published: October 2005

An additional calculation is made of diffraction of Rayleigh waves on homogeneous, isotropic elastic wedges following a formulation by Kane and Spence [Geophys. 28, 715–723 (Oct. 1963)]. For the wedges of which interior angles are close to 180°, power transmission, reflection and radiation coefficients can be derived in simple quadratic forms. Numerical data for rapid estimation of these coefficients are presented as functions of Poisson ratio.

Subject Classification: [43]20.30; [43]35.54.
Use of the cepstrum method for arrival times extraction of overlapping signals due to multipath conditions in shallow water
Authors: Fjell Per O.
Published: October 2005

The use of the cepstrum method for signal arrival times extraction of overlapping signals due to multipath conditions in shallow water is considered. The cepstrum method is applied to signal data from a research cruise. The results fall in two parts: (1) the use of a single cepstrum calculation will not clearly identify the different arrival times and (2) the use of several cepstrum calculations gives a consistant pattern of dominant peaks at or near the calculated arrival times. The assumption made in the cepstrum derivation that echoes are replicas of the first arrival is not correct.

Subject Classification: [43]30.20; [43]60.30; [43]85.84.
Orthogonality relation for the Rayleigh–Lamb modes of vibration of a plate
Authors: Fraser W. B.
Published: October 2005

An orthogonality relation for the Rayleigh-Lamb modes of vibration of an isotropic, homogeneous, elastic plate is derived.

Subject Classification: [43]40.24.
Toward damage risk and habitability criteria for pure-tone pulse trains
Authors: Harris J. Donald
Published: October 2005

Reports from this and other laboratories are summarized to the effect that pulse trains in the 3–4-kHz region, with pulse duration ?1 sec and with on fractions up to 0.05, are habitable when presented a round the clock for weeks, and yield no TTS greater than can be borne, when the level does not exceed 85 dB SPL. For more onerous acoustic loads, a damage risk criterion of 80 dB should be set for long-lasting continuous exposures. The ear is more susceptible to this sort of acoustic load than is any other system of the body, and can serve as an early warning device for potential damage to those systems.

Subject Classification:[43]65.50,[43]65.64, [43]65.66.
Acoustic effects of style of speech
Authors: Ladefoged Peter , Kameny Iris , Brackenridge William
Published: October 2005

Recordings were made of nine subjects producing test words in seven different styles, varying from completely informal conversation to reading the test words in lists. The subjects were all educated male speakers of standard English who had lived in Southern California from an early age. The data were analyzed using a computer system that determined the frequency, amplitude, and intensity of the first four formants. It was found that the nucleus of the vowel was not affected by differences in the style of speech.

Subject Classification: [43]70.40, [43]70.65.
Comments on ’’Species differences in cochlear fatigue related to acoustics of outer and middle ears of guinea pig and chinchilla’’ [J. Acoust. Soc. Am. 56, 929–934 (1974)]
Authors: Sinyor A. , Laszlo C. A.
Published: October 2005

There appears to be a significant discrepancy between the results of Drescher and Eldredge [J. Acoust. Soc. Am. 56, 929–934 (1974)] and those reported by Sinyor and Laszlo on the transmission characteristics of the ear canal of the guinea pig. We suggest that this discrepancy is due mainly to the differences in the conditions of the middle ears of the guinea pigs at the time of measurement.

Subject Classification: [43]65.24, [43]65.22.
Use of calculated sound fields and matched-field detection to locate sound sources in shallow water
Authors: Bucker Homer P.
Published: October 2005

The calculated complex sound field cj for sensor j at depth zj and range rj from a sound source of frequency ω and depth z0 can be written in the normal-mode form as cj= (2π/rj)1/2 ΣmUm(z0) Um(zj) exp[i (kmrj−ωt)]. Here, km is the horizontal wavenumber of mode m and Um is the depth function of the mth mode. It is proposed that the detection factor DF=ΣJj=1 cjc*k〈 (c0jc0k*) *〉 is a reasonable measure for determination of whether a set of sound pressure measurements {c0j} for j=1,2,⋅⋅⋅,J is a good fit to calculated values of {cj} for an assumed location of the sound source. Here 〈 〉 denotes a time average and * denotes complex conjugate. Several examples are shown where a set of {c0j} are calculated for a given source location in a typical shallow water channel and values of DF are then calculated for a grid of range depth or range azimuth locations.

Subject Classification: [43]60.20; [43]30.82.
Nonlinear feedback system for the normalization of active sonar returns
Authors: Ricker Dennis W.
Published: October 2005

The problem of dynamic range reduction for signal-detection systems operating in the presence of reverberation is discussed. An automatic gain-control system is described that utilizes nonlinear feedback to achieve a high degree of signal envelope normalization over a wide dynamic range. It is shown that the system is characterized by loop dynamics that are insensitive to input level, an improvement over linear, automatic gain-control systems in which loop gain increases with background level which causes increased echo distortion.

Subject Classification: [43]60.30, [43]60.50, [43]30.82, [43]30.40.
New method for normal-mode models of sound propagation in the ocean
Authors: McKisic J. Michael , Hamm D. P.
Published: October 2005

Newman and Thorson have recently proposed and developed a new method which permits the rapid and efficient solution of eigenvalue problems associated with linear second-order differential equations. Results on applications of the method to problems of interest in underwater acoustics are presented.

Subject Classification: [43]30.20; [43]20.40; [43]30.50.
Quick sound-velocity measurements by an improved pulse-superposition method
Authors: Ishizaki Kozo , Spain Ian L. , Bolsaitis Pedro
Published: October 2005

This paper discusses a modification of the McSkimin technique which permits measurements on acoustically soft solids of poor quality with a higher accuracy than is possible with the conventional McSkimin technique.

Subject Classification: [43]85.22; [43]35.26, [43]35.80.
Low-frequency attenuation in the Pacific Ocean
Authors: Mellen R. H. , Browning D. G.
Published: October 2005

There is increasing evidence that the low-frequency sound absorption in the Pacific is less than that in the Atlantic. The origin of the excess absorption below 1 kHz has recently been identified as a boron relaxation. A compilation of available Pacific data appears to show one-half the boron absorption found in the Atlantic, which suggests significant differences in the chemical composition of the oceans.

Subject Classification: [43]30.20, [43]20.35.
Ballistic range experiments on the superboom generated at increasing flight Mach numbers
Authors: Sanai M. , Toong T.-Y. , Pierce A. D.
Published: October 2005

Ballistic range experiments for the study of the propagation of converging shocks are described and the similarity between the observed phenomenon and that expected for superbooms created by accelerating supersonic aircraft is discussed. For weak shocks (shock Mach numbers of about 1.03), a structure resembling that of a folded shock predicted by geometrical acoustics theory is observed while for stronger shocks, a concave front with enhanced overpressure is recorded. Other results are in general accord with the basic concepts of shock propagation and in conjunction with some theoretical scaling laws indicate that the peak magnification of sonic booms due to aircraft flight acceleration in the real atmosphere should be in the range of 6 to 13.

Subject Classification: [43]25.20, [43]25.30; [43]28.55; [43]50.55.
Investigation of laryngeal control in speech by use of thyrometer
Authors: Kakita Yuki , Hiki Shizuo
Published: October 2005

Laryngeal control in speech was studied by observing vertical laryngeal movements using the ’’thyrometer,’’ an optoelectric device. The thyrometer consists of a light source casting a narrow beam of light onto a small mirror stuck to the skin of the neck over the laryngeal cartilages and a special photocell which picks up the reflected light beam. Vertical movements of the laryngeal cartilages tilt the mirror and thus change the angle of reflection of the light beam onto the photocell which converts the change in the angle of the light into a voltage monotonically related to the original laryngeal movements. This method yields a highly sensitive recording of the vertical movements of the larynx in running speech without causing any significant impediment to normal articulation. Using this device investigations have been made of the laryngeal mechanisms employed in the production of the following: step-function changes in pitch, word accents and sentence intonation in Japanese, and the four tones of Mandarin Chinese. The correlation between vertical larynx movement and the activity of the laryngeal muscles for pitch control is discussed based on some electromyographic data and the anatomical structure of the larynx.

Subject Classification: [43]70.60, [43]70.20.
Speaker sex identification from voiced, whispered, and filtered isolated vowels
Authors: Lass Norman J. , Hughes Karen R. , Bowyer Melanie D. , Waters Lucille T. , Bourne Victoria T.
Published: October 2005

The purpose of this investigation was to determine the relative importance of the speaker’s laryngeal fundamental frequency and vocal tract resonance characteristics in speaker sex identification tasks. Six sustained isolated vowels (/i, -, -, a, o, u/) were recorded by 20 speakers, 10 males and 10 females, in a normal and whispered manner. A total of three master tapes (voiced, whispered, and filtered) were constructed from these recordings. The filtered tape involved 255 Hz low-pass filtering of the voiced tape. The tapes were played to 15 listeners for speaker sex identification judgments and confidence ratings of their evaluations. Results of their judgments indicate that, of the 1800 identifications made for each tape (20 speakers × 6 vowels × 15 listeners), 96% were correct for the voiced tape, 91% were correct for the filtered tape, and 75% were correct for the whispered tape. Moreover, the listeners were most confident in their judgments on the voiced tape, followed by the filtered tape, and showed the least amount of confidence on the whispered tape. These findings indicate that the laryngeal fundamental frequency appears to be a more important acoustic cue in speaker sex identification tasks than the resonance characteristics of the speaker.

Subject Classification: [43]70.30.
Asymptotic behavior of the acoustic nearfield of a circular piston
Authors: Stepanishen Peter R.
Published: October 2005

The acoustic nearfield of a circular piston is investigated using the impulse response technique. Although the harmonic field can be expressed as either a convolution integral or Fourier transform, the integrals cannot be simply evaluated. An asymptotic evaluation of the Fourier transform of the spatially dependent impulse response for the circular piston is, however, readily performed. The resulting expressions very simply illustrate the nearfield behavior of the piston. Furthermore, the expressions are shown to be in agreement with the asymptotic properties of known nearfield results and are consistent with the usual farfield expressions.

Subject Classification: [43]20.55, [43]20.15.
Tactile localization of sounds: Acuity, tracking moving sources, and selective attention
Authors: Frost B. J. , Richardson B. L.
Published: October 2005

Most attempts to design artificial ears have concentrated on displaying frequency information to the skin of deaf subjects in the hope that they may recognize complex patterns of sounds and thus have some ’’auditory function’’ restored. The problem from a practical standpoint is that simultaneously occurring sounds that originate from different sources are difficult if not impossible to unscramble. In normal audition, auditory localization not only enables subjects to perceive the locus of origin of sounds with a high degree of accuracy, but also appears to be the most important determinant of selective auditory attention. The three experiments reported in this paper demonstrate first of all that tactile sound localization is possible with an accuracy that approaches normal audition, and secondly that subjects can track moving sound sources. Finally, an analog of selective auditory attention was found by using tactile localization. These experiments show the utility of incorporating a localization unit in future designs of artificial ears for the completely deaf.

Subject Classification: [43]65.62, [43]65.70.
Perception of the missing fundamental by cats
Authors: Heffner Henry , Whitfield I. C.
Published: October 2005

Two cats were tested on their ability to perceive the missing fundamental through the use of an avoidance technique. The animals were trained to discriminate between rising and falling pitch sequences first with single and then with multiple tones. They were then tested by presenting them with tone triads known to produce the perception of the missing fundamental in humans. In these triads, the pitch of the frequencies composing the triad either remained the same or shifted in the direction opposite the shift of the missing fundamental. The results show that the animals’ response to these triads was not in conformity with that expected from the direction of change of the component frequencies, but could be accounted for if it were assumed that the cats were responding on the basis of the missing fundamental. A further test given one of the cats indicated that this phenomenon declined progressively as the center frequency was raised, until at 6 kHz it was apparently completely absent. A similar decline in the strength of the fundamental pitch occurs over the same range in humans. Thus, there is reason to believe that cats perceive the missing fundamental.

Subject Classification: [43]65.75, [43]65.56, [43]65.54; [43]80.50.
Effects of sea-ice ridges on sound propagation in the Arctic Ocean
Authors: Diachok O. I.
Published: October 2005

An environmental/acoustic model of sound propagation in the Arctic Ocean, which accounts for reflection losses from ridged sea ice, has been developed. In this model sea-ice ridges are represented as infinitely long, randomly distributed, elliptical half-cylinders. Under-ice reflection losses for acoustic wavelengths either large or small compared to ridge dimensions are computed from theoretical equations as a function of average keel depth and width, number of ridges/km, and grazing angle. Numerical values of under-ice reflection loss as a function of grazing angle are then incorporated into ray-theoretical computations of transmission loss assuming a single sound- speed profile which is characteristic of the central Arctic Ocean. The validity of the concepts and approximations, the limitations of the model, and the accuracy of coincident measurements of environmental and acoustic parameters required to validate the model are discussed. To illustrate the predictions and accuracy of the model under diverse ice conditions, several comparisons of theoretical and experimental determinations of under-ice transmission loss in the central Arctic Ocean are presented. Midwater absorption loss, a complicating feature of transmission loss measurements at high frequencies, is also considered.

Subject Classification: [43]30.20, [43]30.30.
Tilted directional response patterns formed by amplitude weighting and a single 90° phase shift
Authors: Hughes W. Jack , Thompson William
Published: October 2005

It is shown that by appropriately processing the output signals of the elements in a symmetric array, a tilted sum pattern or difference pattern can be produced without numerous delay lines or phase-shift networks. The tilted pattern is achieved by combining, in proper phase, two outputs of an array; the first output is that of a particular amplitude weighted phase-symmetric array while the second is that of a particular amplitude weighted phase-antisymmetric array. To achieve the proper phase relationship between these two outputs, one of them must be phase shifted by ±90°. Theoretical calculations and experimental results are presented for the case of a line array of nine elements that are equally spaced a half-wavelength apart; both a sum pattern and a difference pattern tilted to 30° from the normal to the line array, by this method, are shown. The variation of the side-lobe levels of these tilted patterns is examined as the ±90° phase shift is perturbed. The possibility of using this technique to continuously vary the angle of tilt is discussed.

Subject Classification: [43]20.55; [43]30.50; [43]60.30; [43]35.54.
Intensity preception. VI. Summary of recent data on deviations from Weber’s law for 1000-Hz tone pulses
Authors: Rabinowitz W. M. , Lim J. S. , Braida L. D. , Durlach N. I.
Published: October 2005

Data from 15 modern studies are used to characterize the deviations from Weber’s law for intensity discrimination of 1000-Hz tone pulses. The results show that Weber’s law is satisfied in the region 10–40 dB SL, that resolution descreases with decreasing intensity below 10 dB SL and increases with increasing intensity above 40 dB SL, and that resolution at 90 dB SL is roughly 2.5 times better than at 40 dB SL.

Subject Classification: [43]65.50, [43]65.75.
Resiude pitch as a function of component spacing
Authors: Patterson Roy D. , Wightman Frederic L.
Published: October 2005

In an effort to determine whether the pitch shift of the residue is strictly proportional to the frequency spacing between the stimulus components, observers were asked to match the pitch of waves with component spacings of 100, 200, 300, or 400 Hz. The stimuli were sets of 6 or 12 equal-amplitude sinusoids and the position of each set was varied throughout the frequency range in which the resiude was audible. The pitch shift of the residue showed a disproportionate increase with component spacing for stimuli containing low-frequency components. Six-component waves produced slightly larger pitch shifts than 12-component waves, again when low-frequency components were included. As the spectral location of the set increased, both effects decreased; once the lowest component in the stimulus was more than about five times the component spacing, both effects were minimal. The results indicate that the dominance region is a function of the absolute, as well as the relative, frequency of the components in this case.

Subject Classification: [43]65.54, [43]65.35, [43]65.75.
Effects of ultrasound on unicellular algae
Authors: Giordano R. , Leuzzi U. , Wanderlingh F.
Published: October 2005

The effect of ultrasonic irradiation (up to 3W/cm2 and 1 MHz of frequency) on unicellular algae is experimentally studied. It is unambiguously shown that the damage of the cells and their breakage is to be related to cavitation. The dynamics of the breakage is examined from the point of view of practical application.

Subject Classification: [43]80.40; [43]35.75.