bluuebunny/crossref_metadata_2025 huggingface dataset:
Speed of sound in seawater as a function of temperature and salinity at one atmosphere
Authors: Millero Frank J. , Kubinski Thomas
Published: October 2005

The speed of sound in standard seawater (diluted with pure water and evaporated) has been measured relative to pure water with a Nusonics velocimeter as a function of temperature (0 to 40°C, at 5° intervals) and salinity (5 to 40 0/00, at 5 0/00 intervals) at a atm. The results have been fitted to an equation of the form c = c0 + A S (0/00) + B S (0/00)3/2 + C S (0/00)2, where c0 is the speed of sound in pure water, S (0/00) is the salinity in parts per thousand, and A, B, and C are temperature−dependent parameters. The sound speeds fit this equation to a standard deviation of 0.04 m sec−1 over the entire temperature and salinity range. Over the oceanographic range our results, on the average, agree with the work of Wilson to ±0.5 m sec−1 (max 1.08 m sec−1) and with the work of Del Grosso and Mader to ±0.05 m sec−1 (max 0.14 m sec−1). In the low−salinity range, (5−25 0/00 salinity) our results, on the average, agree with the work of Wilson to ±0.3 m sec−1 (max 1.1 m sec−1) and with the work of Del Grosso and Mader to within ±0.1 m sec−1 (max 0.20 m sec−1). From these comparisons it is clear that the 1−atm sound speeds of Del Grosso and Mader are more reliable than those determined by Wilson over the oceanographic range as well as at lower salinities (which is outside of the range of Del Grosso and Mader’s measurements). The adiabatic and isothermal compressibilities of seawater solutions reliable to ±0.003×10−6 bar−1 have been determined from the sound speeds. The isothermal compressibilities are in excellent agreement (avg. dev. ±0.02×10−6 bar) with the direct measurements of Lepple and Millero. The specific heat of seawater solutions at constant volume has also been determined from the sound−derived isothermal compressibilities.

Subject Classification: 30.25.
Vocalic transitions in the perception of voiceless initial stops
Authors: LaRiviere Conrad , Winitz Harris , Herriman Eve
Published: October 2005

Two experiments were conducted in order to test the transition dependency and integration hypotheses of speech perception. These two models emphasize the importance of vocalic transitions in stop−vowel syllables for different reasons. The transition−dependency model regards the vocalic transition as a primary cue for stop identification, and the integration model holds that the transition prevents backward masking. Nine stop−vowel monosyllables were treated, resulting in a set of (1) syllables in which the vocalic transition was deleted (Experiment 1), and (2) various nonsyllabic segments—the aperiodic portion, the aperiodic portion plus the vocalic transition, the vocalic transition, and the vocalic transition plus the vowel (Experiment 2). Recognition scores obtained for these stimuli indicate that the vocalic transition is neither a sufficient nor necessary cue for voiceless stop recognition and that the aperiodic portion of the consonant carries the heaviest perceptual load.

Subject Classification: 70.30.
The orb−web as an acoustic detector
Authors: Finck Alfred , Stewart George M. , Reed Charles F.
Published: October 2005

Movement response of the web of Araneus diadematus Cl. exhibits resonance from 20 to 30 Hz when placed in a sound field of at least 60 dB SPL. Virtually no movement of the web occurred for frequencies above 50 Hz (up to 20000 Hz). Hence it is unlikely that the orb−web serves an an acoustic detector for the approach of flying insects.

Subject Classification: 80.45, 80.50.
Basilar membrane and middle−ear vibration in guinea pig measured by capacitive probe
Authors: Wilson J. P. , Johnstone J. R.
Published: October 2005

Measurements of amplitude and phase were made on the basilar membrane and middle ear of guinea pigs. A subminiature capacitive probe giving wide dynamic range and linearity was used in conjunction with a slave filter to provide continuous frequency response records and a lock−in amplifier to provide high−sensitivity measurements on the basilar membrane down to 40 dB SPL. The results confirm the general features of previous measurements using various optical and Mössbauer techniques but also demonstrate that the mechanical tuning properties of the basilar membrane are equally poor at low SPLs and under excellent physiological condition of the cochlea, as indicated by the threshold of the gross cochlear action potential to clicks. The basilar membrane response conforms to the differential cochlear microphonic rather than the much sharper single cochlear nerve−fiber threshold curve. Linearity of response at the peak of the mechanical curve was observed over an 80 dB range: significant nonlinearities were observed only for frequencies on the high−frequency slope, and then only for sound levels above 110 dB SPL. The existence of an amplitude and phase plateau was confirmed. The peak basilar membrane/incus ratio averaged 29 dB independent of cutoff frequency over a range from 16−43 kHz, with an rms vibration amplitude at the peak of 500 Å at 100 dB SPL over cutoff frequencies in the 16−26−kHz range.

Subject Classification: 65.20, 65.26, 65.24.
On the flow−excited vibrations of cantilever struts in water. I. Flow−induced damping and vibration
Authors: Blake William K. , Maga Lawrence J.
Published: October 2005

The general problem of the response of a cantilever beam to flow over its surface is considered experimentally and theoretically. The model response of a beam in flowing water is shown normalized on the dynamic head of the inflow, the total mass of the beam, and the modal loss factors. Results are presented for a series of beams of varying length and chord. The magnitude of hydrodynamically induced damping is also characterized experimentally. It is shown that results agree favorably with an approximate expression based on finite aspect−ratio, unsteady airfoil theory. Loss factors, based on entrained mass, are found to be inversely proportional to a reduced frequency based on the width of the strut and inflow speed.

Subject Classification: 40.35, 40.22; 30.50.
Monostatic reflection of a plane wave from an absorbing sphere
Authors: Vogt Richard H. , Flax Lawrence , Dragonette Louis R. , Neubauer Werner G.
Published: October 2005

The monostatic reflection from a lucite sphere in water is measured and compared with the exact classical scattering theory. Experimental results do not agree with theory which neglects absorption, in direct contrast to the excellent agreement found when metal spheres are used as targets. The theory is modified to include the effects of absorption of shear and compressional waves in lucite, and agreement between experiment and the modified theory is demonstrated.

Subject Classification: 20.30, 20.15.
Neural responses in the inferior colliculus of albino rat to binaural stimuli
Authors: Flammino Frank , Clopton Ben M.
Published: October 2005

The responses of units in the inferior colliculus of rats were recorded while noise, tone, and click stimuli were presented binaurally. The interaural time and intensity disparities were varied; time to a maximum of 180 μsec in 30−μsec steps and intensity to a maximum of 20 dB in 4−dB steps. Total spike count, probability of firing, and average latency indicated that for most cells contralateral stimuli leading in time or of greater intensity relative to the ipsilateral ear produced increased spike counts and probability of firing and decreased latency of firing. While support is apparent for the influence of both time and intensity cues, the intensity cue would seem to predominate under naturally occuring conditions. A population model for the utilization of these two cues is supported by the data.

Subject Classification: 65.44, 65.62.
Duration−intensity reciprocity for equal loudness
Authors: McFadden Dennis
Published: October 2005

Magnitude estimates were obtained for a 1000−Hz tone presented at all combinations of seven different intensities and seven different durations. Power functions were plotted for each duration separately. These functions were horizontally intersected at several different values of judged magnitude, and the intensities necessary for equal judgment were determined and then plotted as a function of duration. The latter functions, which are analogous to classical acoustic−integration curves, indicate that for equal judged loudness, intensity must be decreased by between 3 and 15 dB for each doubling of duration, depending upon the subject. Thus, for some subjects the acoustic−integration curves for loudness are much steeper than those typically obtained using more conventional techniques.

Subject Classification: 65.50, 65.75.
Comments on ’’Analysis of class IV flextentional transducer by use of wave mechanics’’ [Gerald H. Brigham, J. Acoust. Soc. Am. 56, 31–39 (1974)]
Authors: Lubell Alan H.
Published: October 2005

The purpose of this communication is to point out errors in Sec. III of this very interesting paper and to suggest that the theory of compliance loading [Alan H. Lubell, J. Acoust. Soc. Am. 35, 1905(A) (1963)] might possibly be of use in improving the performance flextentional transducers.

Subject Classification: 30.85.
Reply to  Comments on ’Eigenfrequencies of thin plates and layer potentials’  [P. A. A. Laura, J. Acoust. Soc. Am. 57, 970 (1975)]
Authors: Filippi P.
Published: October 2005

Subject Classification: 40.24.
Statistical properties of wind over the coast and its stochastic model
Authors: Sato Takuso , Sasaki Kimio , Mori Akira
Published: October 2005

The statistical properties of the force of the wind over the coast observed at a fixed point were analyzed by using the bispectrum as well as the power spectrum. The results show that the fluctuation of the wind force, which is regarded as a stochastic signal, is strictly non-Gaussian. As a proper stochastic model of the wind force, the output random signal of a low-pass filter excited by a Poisson impulse sequence is proposed.

Subject Classification: 45.10.
Beat-like interaction between periodic waveforms
Authors: McFadden Dennis
Published: October 2005

It is possible to hear a beat-like interaction between the envelopes of two two-tone complexes, or between the envelope of a two-tone complex and a tone of lower frequency. This monaural effect can be explained as a modulation of the traveling-wave envelope of the higher-frequency complex by the lower-frequency waveform.

Subject Classification: 65.62, 65.60, 65.56.
Harmonic wave propagation in composite materials
Authors: Nelson Richard B. , Navi Parviz
Published: October 2005

This paper presents a study of the propagation of harmonic waves of plane strain in elastic composite materials. The composite structure is idealized as an assembly of identical subregions, each with the displacement field represented by a finite number of generalized displacements. The resulting model possesses a periodic lattice-type structure and its response to harmonic waves can be investigated as a problem in lattice dynamics. A set of generalized coordinates, applicable for the case of harmonic wave propagation in the discrete periodic structure, is employed to generate an algebraic eigenvalue problem, the solution of which gives the frequency spectrum for the medium. To show the accuracy of this method, examples of harmonic wave propagation in infinite isotropic and orthotropic homogeneous plates are presented, and cases of harmonic wave propagation in infinite isotropic and orthotropic media. The method is used to generate the frequency spectra for both a fiber-reinforced composite plate and an infinite composite medium to clearly indicate the dispersive effects which exist in periodic media when the half wavelength–lattice dimension ratio approaches unity. These results are compared with several well-known theories for composite materials.

Subject Classification: 20.15.
Experimental investigation of several passive sonar targets
Authors: Wallace R. H. , Hillery H. V. , Barnard G. R. , Marks B. M. , McKinney C. M.
Published: October 2005

This paper presents the results of an experimental investigation of several passive sonar targets of the types used for calibration, marking, and tracking. Targets studied include spheres, spherical lenses, triplanes, icosahedrons, biconics, and some composite types designed to have specific frequency responses. It is concluded that, of the targets investigated, only the accurately made sphere and spherical lens are suitable for use as calibration standards under the condition of the target being supported by a flexible line. The various corner reflector configurations are suitable for marking, navigation, and tracking. The feasibility of designing passive targets with a specified frequency response is demonstrated.

Subject Classification: 30.30, 30.50.
Dispersion of acoustic waves by fiber-reinforced viscoelastic materials
Authors: Sutherland Herbert J.
Published: October 2005

Acoustic waves are dispersed by two distinct mechanisms as they propagate through a fiber-reinforced viscoelastic material. The first mechanism, viscoelastic dispersion, is characterized by an increase in phase velocity with an increase in frequency, and the second mechanism, geometric dispersion, is characterized as a wave-filtering phenomenon in which periodic waves are selectively transmitted and reflected. To study the interplay between these two mechanisms, the dispersion characteristics of two fiber-reinforced viscoelastic materials were obtained at various temperatures using a water-bath technique. The first composite studied was a cloth-laminate quartz phenolic (2D-QP). Its dispersion characteristics (both phase velocity and attenuation versus frequency) were obtained at seven temperatures, ranging from 4 ° to 40 °C. The second material studied was stainless steel wires embedded in an Epon 828-Z matrix (Epon–SST). Its dispersion characteristics (phase velocity versus frequency) were determined at five temperatures, ranging from 5 ° to 42 °C. The characteristics of these two materials at their low-frequency limits are similar; namely, the phase velocity decreases with increasing temperature. There, the similarity ends. The relatively fine structure of the 2D-QP is weakly dispersive below 4 MHz, and viscoelastic dispersion dominates; whereas the relatively coarse structure of the Epon–SST is highly dispersive below 2 MHz (the cutoff frequency of the first passband was found to be about 1 MHz and this composite behaves as a wave filter.

Subject Classification: 35.26, 35.50.
Hypersonic absorption and velocity in molten potassium nitrate
Authors: Torell Lena M.
Published: October 2005

The spectrum of light scattered from thermal sound waves has been studied by Brillouin spectroscopy in molten potassium nitrate to provide information about the hypersonic velocity and the absorption of thermal waves. Brillouin spectra were investigated in a temperature range of 350–600 °C for scattering angles of 40 °–140 ° to determine the variation of the phonon velocity and attenuation as a function of temperature and frequency. The measurements did not reveal any difference between the sound velocities at a scattering angle of 40 ° (3 GHz) and at 140 ° (10 GHz), but the hypersonic velocities were all higher than the ultrasonic ones. In spite of this fact, considerable decrease in attenuation was observed within the investigated frequency interval, with the value at high frequency approaching the classical limit attributed to shear viscosity. These results indicate a relaxation frequency just below the measured frequency range. The relaxation time for the bulk viscosity coefficient was determined from two independent measurements: (1) the position of the Brillouin lines and (2) the width of these lines. A relaxation theory involving a single relaxation time has been applied and agrees with the experimental results.

Subject Classification: 35.24, 35.35.
Real and imaginary parts of the complex viscoelastic modulus for boron fiber reinforced plastics (BFRP)
Authors: Paxson Ernest B.
Published: October 2005

The general viscoelastic model was chosen to represent the mechanical properties of boron fiber reinforced plastic (BFRP). The experimental configuration selected was that of a thin beam subjected to transverse vibration. The mechanical properties of the beam (in the direction x parallel to the length of the beam) then manifest themselves in the form of a viscoelastic complex modulus E*xx = E\xx + iE\xx. In this investigation the purposes were to measure E′xx and E\xx (and the loss factor) for BFRP and to compare the loss factors for BFRP with that for a metallic material such as aluminum 2024-T4 alloy. Boron laminates used in these studies were fabricated from NARMCO 5505 preimpregnated boron fiber epoxy tape. Values of storage modulus E′xx and loss modulus E\xx as a function of excitation frequency are presented for three fiber orientations, 0 ° (undirectional), ±45 ° (crossply), and 90 ° (all transverse). Also presented is the damping (or loss) factor ηxx as a function of excitation frequency for the three above-mentioned fiber orientations. The values obtained for damping factor are compared with those obtained by measuring exponential decay of BFRP beams initially excited in the free–free mode of vibration.

Subject Classification: 40.60, 40.22.
Utilization of a forced-choice technique to verify statistical performance requirements for detection systems
Authors: Buratti R. J. , Trezona G. E.
Published: October 2005

An automated forced-choice method of evaluating detection performance is employed instead of the familiar fixed-threshold technique. The latter method utilizes a number of preselected, constant thresholds to estimate both detection and false-alarm probabilities, whereas the former incorporates a variable threshold with a precise false-alarm probability to estimate only the detection probability. The advantages of the forced-choice technique are a predetermined false-alarm rate, a single parameter test, less required test time, and real-time monitoring of test results by minimizing the amount of data reduction. A comparison of both techniques is presented for two sets of statistics which are representative of those typically encountered in detection systems under test conditions. Because of the uncertainty associated with the variable threshold, the forced-choice results are slightly pessimistic, but are within 0.3 dB of the fixed threshold results. However, the forced-choice technique can easily be made equivalent to the fixed-threshold procedure by incorporating a correction factor into the test procedure.

Subject Classification: 60.20, 60.30.
Spectrum restoration for uniformly spaced arrays
Authors: McDonough R. N.
Published: October 2005

An ambient narrow-frequency-band acoustic field is described by the power density function N (cos ϑ), with ϑ the bearing angle from a line array of sensors. This field is observed through a conventional delay-and-sum beamformer, with average power output B (cos φ) when steered to bearing φ. We present a method (spectrum restoration) for obtaining the (wavenumber) bandlimited version of N from observed values of B. We consider only uniformly spaced arrays, and treat two computationally distinct situations: Δ < λ/2 and Δ ? λ/2, where λ is the wavelength of the narrow-band field incident on the array and Δ is the array element spacing. In the former case, our method is only approximate; however, it can be carried through computationally, in contrast with methods proposed earlier, which in general succeed only for the case Δ ? λ/2. Computational results are presented for a variety of simulated noise fields, indicating sharper resolution and decreased side-lobe levels in the obtained field restoration, as compared with the beamformer response.

Subject Classification: 60.20.
Theoretical analysis of detection of monaural signals as a function of interaural noise correlation and signal frequency
Authors: Osman Eli , Tzuo Huan-yuan , Tzuo Pi-fong Lin
Published: October 2005

Results of Wilbanks and Whitmore on the binaural detection of monaurally presented tones in broad-band noise for interaural noise correlation ranging from 0 to +1 and signal frequency ranging from 150 to 4000 Hz are reexamined. The appropriate equations and corresponding curves based on the equalization–cancellation and correlation models are compared to each other and to the equation and curves presented by Wilbanks and Whitmore. The Wilbanks and Whitmore ’’empirical ’’ equation is shown to be a special case of the correlation model equation.

Subject Classification: 65.62, 65.60, 65.58.
Speech reception with low-frequency speech energy
Authors: Rosenthal Ruth D. , Lang James K. , Levitt Harry
Published: October 2005

The effects of low-frequency speech bands on consonant reception were investigated. A recording of the Fairbanks Rhyme Test was filtered such that four passbands were produced; a high band of 1100–2200 Hz and three low bands of 55–110, 110–220, and 220–440 Hz, respectively. Articulation scores were determined for the high band only and for the high band in combination with each of the low bands for both monotic and dichotic listening conditions. Additional data for the low-band-only conditions were also obtained. The relative gain of the low band was varied in steps of 10 dB from 0 to 40 dB. Results indicated that, compared with scores for the high band only, presentation of any one of the low bands significantly increased articulation scores and that this increase was greatest for the 220–440-Hz band in combination with the high band. An analysis of the data in terms of articulatory features showed the greatest improvement in the reception of voicing, a substantial improvement in the reception of manner of articulation, and a moderate improvement in the reception of place of articulation. Of the various consonants sampled in the rhyme test, the nasals benefited most from the additional low-frequency information. There was also a substantial improvement in the reception of plosives and the lateral, a moderate improvement in the reception of voiceless fricatives, and no measureable improvement in the reception of the glides. The relevance of these findings for the design of speech reception aids for the hearing impaired is discussed.

Subject Classification: 70.30, 70.55.
Comment on ’’Level and zero crossing in volume reverberation signals’’ [R. C. Spindel and P. T. McElroy, J. Acoust. Soc. Am. 53, 1417–1426 (1973)]
Authors: Ehrenberg John E. , Erickson Carl A.
Published: October 2005

Spindel and McElroy [J. Acoust. Soc. Am. 53, 1417–1426 (1973)] used the zero crossings of a reverberation process to obtain an estimate of the spatial density of scatterers. Errors in their analysis resulted in an intuitively incorrect relationship between the scattering density and the reverberation zero crossing rate. The errors in their analysis are discussed, and, using a different approach, an intuitively correct expression for the zero crossing rate is derived for the special case of a rectangular sinusoidal transmitted pulse and Rayleigh distributed echo amplitudes.

Subject Classification: 30.40; 60.20.
Supplement to ’’Method of Calculation of Frequencies of Partially Fixed Beams Carrying Masses’’ [C. L. Amba-Rao, J. Acoust. Soc. Am. 40, 367–371 (1966)]
Authors: Amba-Rao C. L.
Published: October 2005

Using finite Fourier sine transforms, it is possible to obtain frequencies and mode shapes of beams with masses and any unequal elastic restraints at the supports.

Subject Classification: 40.22.
Estimating CNC discrimination with spondee words
Authors: Bode Daniel L. , Carhart Raymond
Published: October 2005

Five experiments with normal listeners were performed to determine the percentage of CNC monosyllables correctly identified in various presentation paradigms at the speech reception threshold (SRT) for spondee materials. The purpose was to obtain information which would allow the quick estimation from the SRT of the stimulus level yielding these CNC percentages. Descending, simple-up-and-down, and best-of-three measuring techniques were used for SRT tests, and best-of-five, doublet, and constant-level tests were employed for measuring CNC discrimination. All tests involved monaural (earphone) listening conditions in quiet or against a background of either 60 or 80 dB SPL white noise. Findings revealed that the various SRT tests estimated percentage CNC discrimination scores ranging in about 17–29% on the rising portion of articulation functions. In general, present results indicated that SRT tests are most apt to measure approximately the 23% point on CNC functions for normal listeners.

Subject Classification: 70.35.
Cancellation of turbulent boundary-layer pressure fluctuations
Authors: Kennedy Robert M.
Published: October 2005

An optimum beamforming scheme has been applied to a system of sensors flush mounted in a turbulent boundary-layer pressure field. It is shown that flow noise propagating at subsonic velocities can be significantly discriminated against while passing, undistorted, a sonic signal. Two- and three-sensor systems are evaluated and extrapolations to a N-sensor case are made. Comparisons of the two- and three-sensor cases are made with a single sensor of finite size as well as with some previously reported results from a method by Jorgensen and Maidanik (J. Acoust. Soc. Am. 43, 1390–1394 (1968)].

Subject Classification: 30.70, 30.85.
Amplitude shading of sonar transducer arrays
Authors: Wang H. S. C.
Published: October 2005

Amplitude shading is an important technique for controlling the beamwidth and sidelobe level of transmitting and receiving arrays in sonar and radar. The traditional method of Dolph–Tchebyscheff synthesis for the determination of array amplitude shading or weighting coefficients is, however, highly restrictive despite the extension and generalizations by many workers following Dolph. This paper outlines an entirely new method of finding these shading coefficients by minimizing the power received by the array in an isotropic noise field exclusive of a three-dimensional spatial slice around the mainbeam direction. The method is completely general in the sense that it is applicable to any discrete array of transducers arbitrarily distributed in a three-dimensional space. As an illustrative example, nonuniformly spaced linear arrays (which are necessary for reasons of economy and operation over a band of frequencies) are shown to have been successfully shaded to acceptable pattern shape and sidelobe levels. In the special case of equally spaced linear transducer arrays, the new method of shading yields an essentially identical mainbeam shape as Dolph–Tchebyscheff’s for the same sidelobe level, while the total power received (or transmitted) via the sidelobes is actually slightly less than one half of that by the latter synthesis. Necessary detailed mathematical formulas for applying the method to circular or arc arrays are also suggested.

Subject Classification: 30.82; 20.15; 60.30.
Wave propagation in nonuniform elastic rods
Authors: Rosenfeld Gerald , Keller Joseph B.
Published: October 2005

Asymptotic solutions are obtained for elastic waves propagating in any nonuniform rod, with an arbitrary cross section which varies slowly along the length of the rod. The solutions are valid when the variation in cross section along the rod is sufficiently slow. For each mode the result is of the WKB type, involving a phase function, an amplitude function, and a mode form. The phase velocity and the mode form at each cross section are obtained from the solution for the corresponding uniform rod. The amplitude function is obtained from an equation which is equivalent to conservation of energy. An application of the results is made to long waves. The linear theory of elasticity is used throughout.

Subject Classification: 40.20, 40.22; 20.15.
Motion of a three-layered elastic–viscoelastic plate under fluid loading
Authors: Sandman B. E.
Published: October 2005

A mathematical model of a three-layered plate structure is employed to study the vibration characteristics of a composite panel under the influence of fluid loading. The effects of heavy, in-water fluid loading is adapted in the analysis by the definition of normal and cross-coupling coefficients for the acoustic pressures which accompany the normal modes of vibration. The numerical solution is presented for relatively low-mode resonant response. The results indicate that structural stiffness and damping constitute primary factors in the resonant response and radiated pressures displayed by a finite rectangular plate. It is shown that constrained-layer damping, a normal-mode component, affects a significant reduction in the degree of cross coupling between resonant and nonresonant modes.

Subject Classification: 40.24; 20.15.
Moment impedance of internally damped rectangular and square plates with simply supported boundaries
Authors: Snowdon J. C.
Published: October 2005

Theoretical expressions for the moment impedances of simply supported, internally damped, rectangular and square plates are presented. The plates are driven either centrally or at an arbitrary point by a bending moment, the line of action of which has arbitrary direction. In calculations made to illustrate the frequency dependence of moment impedance, plate damping of the solid type has always been assumed. The expressions for moment impedance do not contain a logarithmic term that becomes infinitely large as the separation of the moment-producing pair of forces normal to the plate surfaces is reduced to zero, and so contrast with prior expressions that have been derived for the moment impedance of infinite plates.

Subject Classification: 40.24.
Infant cry sound; developmental features
Authors: Prescott Robin
Published: October 2005

The breath group was employed as the unit of analysis in measures of longitudinal samples of infant cry. Developmental trends were seen in decreased durations of intra-utterance silences. Small but reliable increases in intra-utterance pitch variability were observed for both longitudinal and independent samples of cry. Measures of the cries of a six-months-old hearing impaired child suggested that the above features merit further investigation as possible functions of both audition and maturation.

Subject Classification: 70.20.
Low-frequency propagation via shallow refracted paths through deep ocean unconsolidated sediments
Authors: Christensen R. E. , Frank J. A. , Geddes W. H.
Published: October 2005

The shallow refracted path through sea floor sediments plays a significant role in the transmission of acoustic energy at low frequencies. Explosive data from three bottom acoustics stations, located in the Caribbean Sea and Bering Sea, were processed through a high-bandpass (2 to 20 kHz) filter and a low-bandpass (20 to 200 Hz) filter. Bottom returns at the high frequencies were found to be reflections. Bottom returns at the low frequencies were found to come from both reflected and refracted paths. For bottom grazing angles of 90 ° to 25 ° low-frequency acoustic energy was observed to come from reflected paths. For bottom grazing angles of 25 ° to the angle of intromission (10 °) the dominant contribution of low frequency acoustic energy comes from shallow refracted paths through the sediments. At angles less than the angle of intromission, low-frequency acoustic energy appears to be received from both the refracted and the reflected paths. The refracted path is possible because of the positive velocity gradient within the sediment. The sudden emergence of the refracted arrival is related to the overall sound path length in the sediment and sediment absorption of sound. Since sediment absorption is directly proportional to frequency, only low-frequency energy is transmitted via this path. The refracted path should exist wherever unconsolidated sediments exceed a thickness of a few hundred feet.

Subject Classification: 30.20, 30.30.
Effect of a dense gas equation of state on the expansion and contraction of an underwater gas bubble
Authors: Epstein David
Published: October 2005

At the high pressure believed to occur in underwater explosion gases, and in cavitation gas bubble collapse, deviations from an ideal gas must be considered. A theoretical investigation into the effect of a simplified dense gas equation of state on underwater gas bubble dynamics is presented. Our approach is to make a direct comparison between ideal and dense gas results. First, the lossless, incompressible liquid case is analyzed. The requirement of a realistic equation of state yields some startling results, placing severe bounds on some of the key parameters: the peak bubble pressure, the maximum bubble wall velocity, and the minimum bubble radius. Next, nonviscous energy losses are discussed. A generalization of the Herring method is used for approximate evaluation of the radiation-loss integral derived from the Kirkwood–Bethe equation. These calculations appear to give physically reasonable loss estimates under both the ideal and dense gas assumptions. Also, an often-quoted formula for the acoustic radiation loss has been found to be in error and has been corrected. For ease in calculation of some of the important quantities of interest, useful graphs and formulas have been presented.

Subject Classification: 30.60, 30.75; 25.60.
On the flow-excited vibrations of cantilever struts in water. II. Surface-pressure fluctuations and analytical predictions
Authors: Blake William K. , Maga Lawrence J.
Published: October 2005

Analytical predictions of the flow-excited vibration of resonant bending modes of cantilever struts are made. These predictions are compared to selected samples of measured responses of struts in a water tunnel. The measurements have been described in Part I. As a basis for the estimates, a wind tunnel study of the statistical properties of the boundary layer formed by flow on a rigid strut is described. The air measurements were made on a Reynolds-number-scaled model of one of the cantilever struts which were excited by water. For the crude geometry used, the wind results disclose that flow separation at the leading edge (which is sensitive to angle of attack) generates a low-frequency pressure field which is markedly higher than that normally encountered in boundary layers. At high frequencies the pressure field is influenced by the local flow parameters normally used in boundary-layer scaling. Predictions of the response of the struts to inflow turbulence are based on existing theory and measured water tunnel turbulence spectra. The comparisons of the calculations with the measured vibration response indicate that while the response to turbulent inflow is dominant at low frequencies, the response of the strut to its own boundary layer is important at high frequencies.

Subject Classification: 40.35, 40.22, 40.20; 30.70.
Optimal acoustic design of sandwich panels
Authors: Lang Mark A. , Dym Clive L.
Published: October 2005

An optimization study to investigate the feasibility of an optimal acoustic design process for sandwich panels is presented here. Using a pattern search procedure it is shown that the average transmission loss of a panel may be improved through optimization over a range of frequency, and that the optimization procedure results in a shift of the panel symmetric coincidence frequency beyond the range of interest.

Subject Classification: 55.75.
Detection of underwater signals by a California sea lion and a bottlenose porpoise: variation in the payoff matrix
Authors: Schusterman Ronald J. , Barrett Barry , Moore Patrick
Published: October 2005

A sea lion (Zalophus californianus) and a porpoise (Tursiops truncatus) were trained to report the presence of a pure tone under water in yes–no psychophysical procedures. Signal probability was held constant at 0.50. For the sea lion signal strength and payoff matrix were varied concurrently while only payoff matrix was varied for the porpoise. Payoff matrix was manipulated by changing the amount of reinforcement (number of fish) consequent on the two different classes of correct responses—hits and correct rejections. In terms of the ratio of hits to correct rejections the matrix was varied over three values—1:1, 4:1, and 1:4. In the sea lion signal detection improved as signal intensity increased and was independent of the sea lion’s response bias. In the porpoise changes in response bias occurrred as a function of changes in the payoff matrix. Both the sea lion and the porpoise repeatedly demonstrated rapid acquisition of a stable response bias. These experiments demonstrate that varying the payoff matrix may be an effective way to control response bias in experiments dealing with the detection of underwater signals by marine mammals.

Subject Classification: 80.50, 80.60.
Resonant frequencies of cylindrical Helmholtz resonators
Authors: Panton Ronald L. , Miller John M.
Published: October 2005

A simple analysis predicts the Helmholtz and higher modes of cylindrical resonators. Formulas for the quarter-wave tube, the closed tube, and the classic Helmholtz resonator are special cases. It is found that the classic Helmholtz formula begins to lose accuracy for resonator lengths L≳λ/16. A corrected Helmholtz equation is given as an approximation to the exact result. The analysis requires values of inside and outside orifice end corrections. Rayleigh’s model of a piston in an infinite wall and Ingard’s calculations for a piston radiating into a tube give satisfactory results when the theory is compared to experiments. Resonator experiments were performed with k0L in the range π/8 to 3π/8 and orifice to cavity diameter ratios from 0.1 to 0.8.

Subject Classification: 20.40.
Comments on ’’Application of the USRD type E8 tranducer as an acoustic parametric source’’ [A. I. Eller, J. Acoust. Soc. Am. 56, 1735–1739 (1975)]
Authors: Muir T. G.
Published: October 2005

Several practical disadvantages of the E8 as a parametric source limit its suitability as a parametric standard. The relationship of other work reported in the subject paper to previously published work is pointed out.

Subject Classification: 30.75; 25.35; 85.40.
Comments on ’’Effects of prestress on the acoustic behavior of panels’’ [C. L. Dym, J. Acoust. Soc. Am. 55, 1018–1021 (1974)]
Authors: Dym Clive L.
Published: October 2005

The previous paper suggests that the effect of prestress on the transmission loss properties of walls could be salutory. A more detailed examination of these effects demonstrates that the gains are likely to be quite small. However, the observation that this problem couples various effects that might be thought to be unrelated is still valid.

Subject Classification: 55.75; 40.24.
Vowel perturbation as a function of tongue height
Authors: Kasprzyk Patricia L. , Gilbert Harvey R.
Published: October 2005

Ten normal adult male speakers were asked to sustain the vowels ‖i‖, ‖u‖, ‖λ‖, ‖ae‖, and ‖a‖. A perturbation factor was then calculated for each vowel. The results indicated that no relation existed between vocal fold aperiodicity and tongue height associated with vowel production.

Subject Classification: 70.20, 70.40.
Effective length of horns
Authors: Pyle Robert W.
Published: October 2005

Some authors writing about brass musical instruments have used the term ’’effective length,’’ usually meaning the length of a cylindrical tube having the same resonance frequencies as a given horn, but possibly with different end conditions. In this paper, alternative definitions of effective length are considered, and one definition is chosen and generalized to all frequencies, not just discrete resonance frequencies. Within the framework of lossless plane-wave horn theory, a nonlinear first-order differential equation is derived that yields effective length as a function of frequency and horn contour. Effective length has been calculated for some horn contours resembling French horns and trumpets. The solutions are qualitatively consistent with the experience of instrument makers and players, and with the effective lengths of actual instruments, determined from measured resonance frequencies.

Subject Classification: 85.60; 75.40.
Theory of groove deformation in phonograph records
Authors: White James V.
Published: October 2005

This paper describes a theory for predicting the vibrational motion of a phonograph stylus sliding in a modulated record groove. Previous theories of this interaction suffer from two main defects: (1) they are based on the assumption that the groove deformation is perfectly elastic, whereas groove impedance data have shown that this assumption is inappropriate at both high and very low tracking forces; (2) they are based on the assumption that the groove wall shape is paraboloidal in the stylus-contact region. This second assumption is inappropriate when the recorded wavelength is comparable to the width of the contact region and leads to a complete breakdown in these theories at very short wavelengths, where scanning loss is important. This paper describes a generalized formulation of the stylus–groove interaction in which the nonlinear deformation properties of the groove are specified in terms of several functions that can be determined experimentally by measuring the mechanical impedance of an unmodulated groove and by measuring scanning loss. The resulting theory is consistent with existing data on groove impedance and scanning loss. Predictions of nonlinear playback distortion based on this theory compare favorably with experimental results reported by Woodward and Werner on difference-tone distortion. More comparisons with experiment are needed to determine the range of validity of the theory.

Subject Classification: 85.66, 85.68.
Hydroacoustic transduction
Authors: Bouyoucos John V.
Published: October 2005

Professor Hunt once asked, ’’Can you ’blow’ a whistle under water?’’ This question was perhaps the first of a series of events that has led to the emergence of a new power-conversion technology for the efficient conversion of hydraulic power to acoustic or vibratory power. This hydroacoustic power-conversion process embodies flow-switching techniques that are analogous to switching methods that are employed in electronic dc to ac power-conversion practice. The hydroacoustic technology has been developed for the generation of high-power underwater sound for communication and echo location and for such industrial uses as high-frequency rotary percussion rock drilling and pile driving. The origins of the power-conversion technology are reviewed, analytical models used for predicting equipment performance are described, and illustrations of specific applications anticpated by Hunt and the author are set forth.

Subject Classification: 10.60; 30.70; 28.65; 85.40.
The status and future of nonlinear acoustics
Authors: Westervelt Peter J.
Published: October 2005

In addition to serving as an ideal discipline for introducing the concepts of quantum field theory and general relativity, nonlinear acoustics provides a new means for absorbing and generating sound. The many applications of this exciting subject are based in part on the fact that, in common with vector (electromagnetic and shear) and tensor (gravitational) waves, the scalar sound wave transports energy, angular momentum, linear momentum, and, incidentally, information. The methods of nonlinear acoustics can account for such disparate phenomena as the parametric array and the radar time delay in a gravitational field; the absorption of sound in superfluid helium and shock-wave attenuation in a gas; radiation pressure and sonic boom; the scattering of sound by sound; and the generation of gravitational waves. Based on the ability of nonlinear acoustics to subsume within its methodology, and hence to unify, different physical processes, as well as its demonstrated ability to contribute solutions to practical problems, it semms reasonable to expect that this subject will become a part of the curriculum in more colleges and universities than is the case at present.

Subject Classification: 10.60; 25.10.
F. V. Hunt as author
Authors: Schenck Harry A.
Published: October 2005

Professor F. V. Hunt documented what he thought, what he invented, what he learned, and what he accomplished. During a 40-year period, he published over 50 papers and reports. He also authored numerous technical memoranda, one complete book and sections of others, and many key speeches. Many of these contributions were in his classical field of interest, acoustics. However, he made significant contributions in other fields, such as improved instrumentation and education. Through open and classified publications, Professor Hunt greatly influenced the development of U.S. Navy sonar systems. The breadth and impact of this record of accomplishment is examined. Special attention is given to describing the evolution and status of two unfinished books. One of these manuscripts was developed initially to be a major textbook on physical acoustics. The other manuscript began its life as a historical introduction to the text on physical acoustics, became at times a scholarly hobby for Professor Hunt, and grew into a mature draft for a separate book on Origins in Acoustics.

Subject Classification: 05.60; 10.60.
Measurement of acoustic intensity in reactive sound field
Authors: Schultz Theodore J. , Smith P. W. , Malme C. I.
Published: October 2005

The usefulness of direct measurements of vector intensity for the calibration of acoustic transducers has been studied by laboratory experiments in anechoic and reverberant chambers and by analysis. Determination of total power output is feasible by intensity measurements in the nearfield and in reverberant spaces, situations where pressure measurements would be inadequate without elaborate calculation. However, the directional distribution of intensity differs from the farfield, free-space directivity both near a source and far from a source but in a reverberant space. Analysis shows no theoretical way to correct for these differences. In some circumstances, even though intensity measurements do not yield the exact directivity pattern, the differences may be acceptable.

Subject Classification: 10.60; 85.22.
An application of Poisson process models to multipath sound propagation of sinusoidal signals
Authors: Jobst William J.
Published: October 2005

A theory of multipath sound propagation is developed in which the number of rays between a source and receiver is modeled as a Poisson distributed random variable. Using probability distributions obtainable from environmental measurements and acoustic ray tracing programs, moments of the received sound field are derived as functions of space and time. An example is presented in which spatial and temporal coherence are estimated for a horizontal line array. It is shown that spatial coherence decreases with increasing angle from broadside, with increasing frequency, with increasing source speed, and with increasing ray vertical arrival angle at the receiver. Temporal coherence decreases with increasing source speed, with increasing ray vertical angle at the source, and with increasing frequency.

Subject Classification: 20.20; 30.20; 60.20.
Nonlinear resonances in a class of multi-degree-of-freedom systems
Authors: Sridhar S. , Nayfeh A. H. , Mook D. T.
Published: October 2005

An analysis is presented of the superharmonic, subharmonic, and combination resonances in a multi-degree-of-freedom system which has cubic nonlinearity and modal viscous damping and is subject to harmonic excitation. It is shown that in the absence of internal resonances, the steady-state response contains only the modes which are directly excited. It is shown that in the presence of internal resonances, modes other than those that are directly excited can appear in the response. The strong influence of internal resonances is exhibites in numerical examples involving hinged–clamped beams. It is shown that when a multimode solution exists the lowest mode can dominate the response, even when it is not directly excited.

Subject Classification: 40.30, 40.20.