bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytic listening in the goldfish: Simultaneous frequency analysis.
Authors: Fay R.
Published: October 2005

A stimulus generalization paradigm was used with classical respiratory conditioning to determine the extent to which two simultaneous tones are analyzed separately, or ‘‘heard out’’ by the goldfish without explicit differential conditioning. Four groups of animals were used. Two groups were conditioned to suppress respiration to a 6-s pure tone (166 or 724 Hz). They were then tested for generalization to novel tone frequencies from one octave below to one octave above the conditioning frequency. The magnitude of respiratory suppression peaked at the conditioning frequency and declined monotonically toward higher and lower frequencies. Two other groups were conditioned to either 166- and 724-Hz tones alternating on successive trials, or 166 and 724 Hz mixed on every trial at equal sensation levels as a two-tone complex. Both groups were tested identically for generalization to novel pure tones from 79 to 1500 Hz. The generalization functions of frequency for both groups were nearly identical: Suppression responses were largest at the conditioning frequencies and progressively declined at more remote frequencies, producing generalization functions with peaks at the tone frequencies used in conditioning. These results demonstrate that the goldfish acquires independent information about the frequency components making up a complex tone, and thus listens analytically. The resolution of simultaneous frequency analysis is no less than for the same pure tones presented separately. This is the first demonstration of analytic listening in a nonhuman vertebrate. [Supported by a Center Grant from the NIDCD.]
Applying the sonar equation to the detection of a bottom target by an echo-locating dolphin.
Authors: Au Whitlow W. L.
Published: October 2005

The target detection range of two echolocating Atlantic Bottlenose dolphins as a function of target depth in Kaneohe Bay, Hawaii was determined by Murchison [A. E. Murchison, Ph.D. dissertation, Univ. of Calif. Santa Cruz (1980)]. The threshold range decreased monotonically as the depth of the 6.35-cm-diam solid-steel sphere increased and approached the bottom. For the target lying on the bottom, the threshold detection range was approximately 70 m. The scattering strength of the bottom in Kaneohe Bay at approximately the same location of the Murchison’s experiment was recently measured using a simulated dolphin echolocation signal and a transducer tilted at the appropriate grazing angle. The bottom scattering strength along with the target strength of the 6.35-cm sphere and the dolphin threshold range were incorporated into the generalized form of the sonar equation for a reverberation-limited situation and a detection threshold of 4.0 dB was calculated. This detection threshold compared well with the 2.3 dB obtained in an experiment in which the dolphin was required to detect a target in the presence of a clutter screen [W. Au and C. Turl, J. Acoust. Soc. Am. 73, 1676–1681 (1983)].
Attending to multiple discrimination cues.
Authors: Venema Theodore , Espinoza-Varas B.
Published: October 2005

Measures of listeners’ ability to attend to each of four possible discrimination cues were obtained. The stimuli comprised pairs (T1,T2) of 1500-Hz, 80-ms, 66-dB SL tones separated by a 80-ms silent interval [Espinoza-Varas, J. Acoust. Soc. Am. 74, 1687–1694 (1983)]. In a three-interval, 2AFC task, listeners discriminated a ‘‘standard’’ pair (interval 1) from a ‘‘comparison’’ pair (interval 2 or 3) containing increments in the duration (ΔT) or in the frequency (ΔF) of either T1orT2. Each of the four possible increments was controlled by an adaptive track targeting 71-percent-correct thresholds (Levitt, 1971). Separate adaptive tracks were used for each increment, but all four tracks were interleaved randomly within a block of trials. That is, only one kind of increment occurred onagiventrial, but all four increments alternated randomly within a block of trials. Each adaptive track terminated after 10 reversals, and thresholds were defined as the average increment value of the last five reversals. A block of trials terminated when the ten-reversals criterion was reached with all four cues. The slope of the adaptive tracks and the thresholds reached after ten reversals provided measures of attention distribution. [Work supported by OCAST Grant No. HSO-005 and Presbyterian Health Foundation.]
Spectral shape discrimination with random variations in background dimensions.
Authors: Li Xiaofeng , Pastore Richard E.
Published: October 2005

The current research investigated the ability of observers to discriminate a global property of a complex stimulus−the slope of the linear spectral envelope as a function of variation in two background dimensions: fundamental frequency (thus pitch) and a ripple filter function imposed upon the spectral envelope. Two dimensions are judged to be integral if a significant decrement in slope discrimination performance occurs due to a roved relative to fixed background dimension. All experiments used a XAB task with roving overall spectral level within trials to eliminate intensity cues. A significant decrement due to roving fundamental frequency suggests that the linear spectral envelope is integral with fundamental frequency. In contrast, a strikingly small decrement due to roving the ripple filter function suggests that the linear spectral envelope is more easily separable from the ripple filter function than from fundamental frequency. Therefore, the global property of slope of the linear spectral envelope may be unitized with pitch, but is relatively independent of a modest (4-dB) variation in the actual spectral envelope. [Work supported by NSF.]
The influence of spectral composition of complex tones and of musical experience on the perceptibility of virtual pitch.
Authors: Preisler Annemarie
Published: October 2005

Fifty-eight trained musicians and 58 naive listeners were instructed to adjust pure tones, generated by a computer-soundsampler system (ATARI MEGA/STE, AKAI S1100), to the perceived fundamental frequencies of alternatively presented harmonic complexes. Stimuli varied according to the number of their partials, the relative distance to the missing fundamental, and spectral density. Every person had to fulfill 112 different items. The degree of task difficulty was determined by the average of deviations of subjects’ performances from the greatest common submultiples of the complexes. It is shown that each of the considered variables has significant influence on fundamental frequency estimation. Moreover musicians tend to tune fundamentals to low (average: −17 Cent) whereas for nonmusicians the opposite trend is observed (average: +15 Cent). Results were related to performances on the subtests ‘‘Virtual/Spectral Test’’ [M. E. Albrecht, doctoral thesis (1972)] and ‘‘Interval-Classification’’ (Preisler, 1991) by a statistical ANOVA design. Interactions between performance scores are discussed with respect to their theoretical background. [Work supported by the Austrian Fonds for Scientific Research.]
Infant psychometric functions: Asymptotic performance.
Authors: Bargones Jill Y. , Marean G. Cameron , Werner Lynne A.
Published: October 2005

Psychometric functions have been obtained for detection of repeated, short (16-ms) tone bursts [L. A. Werner and G. C. Marean, Assoc. Res. Otolaryngol. (1991)] and for single, long (300-ms) tone bursts [J. Y. Bargones and L. A. Werner, Assoc. Res. Otolaryngol. (1992)] from infants and adults. Infant functions for these stimuli are similar: they tend to have shallower slopes and lower upper asymptotes than those of adults. Best infant performance for both stimuli is about 85% correct. Infant thresholds are also worse than those of adults, but this may result partially from the fact that thresholds were estimated using methods that assume an upper asymptote of 100%. However, most studies of infant threshold present a series of long duration, repeated stimuli. In the current study, upper asymptotic performance for this more optimal stimulus was examined. The observer-based psychoacoustic procedure [Olsho etal., Devel. Psychol. 23, 627–640 (1987)] was used to test 6- to 9-month-old infants. The stimulus consisted of 1-kHz tone bursts, with 500-ms duration. The tone was presented about 25 dB above previously estimated threshold for a similar stimulus. Asymptotic performance was predicted for this stimulus. On signal trials, the tone burst was repeated four times, with 500 ms between bursts. No-signal trials consisted of 4 s of silence. A 30-trial block, consisting of 15 signals trials and 15 no-signal trials, was obtained from each infant to estimate p(C)max. These data were used to estimate the effect of reduced upper asymptote on infant threshold estimates. [Work supported by NIH Grant No. DC00396.]
Discrimination of frequency transitions as a function of spectral and temporal psychoacoustic cues.
Authors: MacNeil J. F. , Slawinski E. B.
Published: October 2005

The present study examined discrimination of short duration frequency glides (60 ms) analogous to the second formant transition of speech. An interdependence of rate of change, frequency excursion, and duration complicates the study of frequency transitions, and to determine how these psychoacoustic cues impact upon perceptual decisions stimuli in the current studies varied as a function of offset frequency and rate of change. Three continua of computer synthesized signals were used to determine just noticeable differences (jnds) for signals described by: a constant onset frequency with diverging offset frequencies; varying onset frequencies with a constant offset frequency; and varying offset frequencies with a constant rate of change. To attenuate frequency onset information, a 20 ms of octave-band noise was appended to the beginning of each signal. Results showed that discrimination improved as a function of the available psychoacoustic information: covarying transition rate and offset frequency yielded smaller jnds than varying either offset frequency or rate of change alone. Discrimination of transitions is not a simple function of frequency excursion or rate of change and integration of rate-related and spectral properties is speculatively important in perceptual decisions regarding complex signals such as speech.
Apparent contribution of respiratory gas exchange to the in-vitro ‘‘cell density effect’’ in ultrasonic cell lysis.
Authors: Brayman Andrew A. , Doida Yukio , Miller Morton W.
Published: October 2005

Ultrasonic cell lysis invitro varies dramatically with cell volume density; densely suspended particles are thought to interfere with gas body activity. The general postulate that the ‘‘cell density effect’’ can be explained in part by cellular modification of the suspension medium by respiratory gas exchange was experimentally tested. Ultrasonic cell lysis occurred at higher levels in suspensions supplemented with the respiratory inhibitor NaCN than in control suspensions when suspension densities exceeded 2×107 cells/ml. At constant cell density, cell lysis diminished with increasing pre-insonation incubation time at 37 °C; the rate of this change was diminished significantly by cyanide treatment. These observations are consistent with the postulate that respiratory O2:Co2 exchange enriches the medium in CO2 while depleting the medium of O2, which cavitates more readily than CO2, thereby diminishing the potential for cavitation-related cell damage. However, this is only a partial explanation of the cell concentration dependence of cell lysis; cell density perse is an important factor in the phenomenon.
A comparison of hemolytic and sonochemical activity of ultrasonic cavitation in a rotating tube.
Authors: Miller Douglas L. , Thomas Ronald M.
Published: October 2005

Cavitational bioeffects of ultrasound invitro may potentially result either from mechanical or from sonochemical mechanisms. Mechanical hemolysis was assessed in a 60-rpm rotating-tube system with unfocused 1.61-MHz exposure by the spectrophotometric method. Free radical generation was assessed by the terephthalic acid dosimeter, calibrated by gamma-ray dosage. Sonochemical production was assessed by measuring residual hydrogen peroxide using the isoluminol/microperoxidase method. Longer durations were needed for the free radical (e.g., 4 min) and hydrogen peroxide (e.g., 15 min) tests than for the hemolysis tests (e.g., 16 s). The sonochemical mechanism was relatively more important for increasing intensity (2.8 to 11 W/cm2 SpTa), and increasing temperature (2, 12, 20, and 37 °C). Bubbling with argon before exposure appeared to enhance both mechanisms. Burst mode exposure (10-μs bursts, 1:1 or 1:3 duty cycles) reduced cavitation activity, but gave relatively greater sonochemical activity for constant temporal average intensity. The results should be helpful for selecting exposure conditions suitable for studying bioeffects related to the sonochemical mechanism. [Supported by PHS Grant No. CA 42947 awarded by the National Institutes of Health.]
An examination of echocontrast enhancement by frequency-modulated acoustic pulses.
Authors: Fowlkes J. B. , Tan J. X. , Carson P. L. , Rubin J. M.
Published: October 2005

Albumin-encapsulated microbubbles (3-μm median diam) suspended in a 5% bovine albumin solution, or in canine urine or whole blood were subjected to 1-s acoustic pulses with pressure amplitudes of up to 4 bars and frequency sweeps between 1 and 10 MHz. Experimental measurements indicated a differential increase in the frequency-dependent backscatter and attenuation when the frequency within the pulse decreased with time (referred to as a ‘‘prich’’) rather than increased (‘‘chirp’’). The decreasing frequency of the prich pulse would more closely follow the resonance frequency of bubbles being grown by rectified diffusion and is thus a possible explanation for the dependence of scattering and attenuation on the frequency sweep direction. Rectified diffusion theory suggests an optimum frequency modulation for maximum bubble growth. A theoretical investigation is presented which examines the effects of the bubble size distribution, rectified diffusion, radiation pressure, and other parameters on the acoustic backscatter and attenuation measured in the present experimental system and the potential efficacy of an echocontrast enhancement system in medical imaging applications. [Work supported by NIH 1R01-DK42290.]
Exposure levels for lung hemorrhage and other bubble effects in vivo.
Authors: Frizzell Leon A.
Published: October 2005

The lungs of neonatal mice were exposed insitu to 1-MHz pulsed ultrasound (10-μs pulse duration, 1-kHz pulse repetition frequency) for durations of 2.4 and 180 s at 10 °C. The neonates were mounted in a special holder that was placed in a tank of physiologically compatible coupling medium such that the broad focal region of the transducer was centered on the dorsal surface overlying the lungs. After removal of the animal from the holder the lungs of sonicated and sham control animals were carefully removed and examined under a dissecting microscope by a second person, who did not know whether the specimen was a sham or sonicated animal, for signs of hemorrhage. The threshold levels for lung hemorrhage are well below those for bubble effects reported in other tissues, but in good agreement with levels reported for hemorrage in adult mouse lung [S. Z. Child etal., Ultrasound Med. Biol. 16, 817–825 (1990)]. The dependence upon on-time for the lung hemorrhage was similar to that for bubble effects in other tissues.
A partial review of path integrals for waves in random media.
Authors: Berman David H.
Published: October 2005

Path integrals are a convenient way to express exact solutions of the parabolic equation for wave propagation in variable media. Although path integrals can rarely be evaluated in closed form, the dependence of path integrals on spatially varying indices of refraction is explicit. This makes path integral solutions of the wave equation well suited for describing effects of randomly fluctuating refractive indices, and also well suited to developing classes of approximations that might otherwise go unnoticed. Moments of fluctuating fields are formed by approximation of exact path integral solutions. This is in contrast to moment methods, in which exact differential equations for the moments are approximated and then solutions for these approximate equations are developed. Here approximations for the path integral which replace integration over all paths by integration over a restricted class of paths will be discussed. This procedure gives a variant of the Rytov approximation, and moments are computed as if there were an effective phase screen. In appropriate limits this variant of the Rytov approximation gives Born scattering and the standard eikonal or WKB approximation. [Work supported by U.S. Naval Research Laboratory.]
Testing the results of stochastic modeling.
Authors: Ewart T. , Reynolds S.
Published: October 2005

It is essential that models of the stochastic behavior of a propagating wave field represent experience. In the field of wave propagation in random media, few data sets are available where the stochastic index of refraction fluctuations are known sufficiently well to allow their use as input to stochastic propagation models. Only in those few cases can the model predictions be compared with the observed wave statistics. Interestingly enough, the statistical stability of ocean internal waves makes the study of this phenomena in the context of ocean acoustics a mechanism for model testing. Here a few of the available data sets are discussed and the success of the testing process is assessed. Data sets may be obtained using Monte Carlo methods to generate the random medium. Various propagation models then produce the statistically varying random fields. Such methods are valuable when used to provide initial testing of models, and for extrapolation of the results to ranges of scattering parameters not available in field experiments. Examples comparing predicted and measured moments of a propagating wave field will be discussed. A summary of unanswered questions will be proposed.
Parabolic equation average propagation routine: Some results.
Authors: Oba Roger M.
Published: October 2005

Results from a routine for computing the average solution to the generalized parabolic equation are presented. The parabolic equation average propagation routine (PEAP) uses profiles that are depth dependent but piecewise range independent with common intervals of invariance [R. M. Oba, J. Acoust. Soc. Am. 90, 2300 (1991)]. It uses analytically computed averages of normal mode solutions of the parabolic wave equation. Its application in the case that the probability distribution can be parametrized by one variable are demonstrated. Validation against averages of multiple runs of deterministic models have been performed. Features of the average solution transmission loss and phase change are shown and compared to deterministic solutions. The extensions to several parameters will be discussed. [Work supported by ONR/NRL-SSC and ONR Young Navy Scientist Program.]
Incoherent ocean bottom scattering from non-Gaussian slopes in the Pacific.
Authors: Dicus Ronald L.
Published: October 2005

Kirchhoff scattering theory was applied to measurements of bottom scatter to explain the time and angle spread of signals received on a horizontal array. The data were collected during ‘‘Pacific Echo II,’’ a joint experiment conducted by the U.S. Naval Research Laboratory and the Canadian Defence Research Establishment Pacific. Source signals were standard MK-61 SUS charges detonated at 244-m depth. The array was 300 m long, towed at 4 kn and 200-m depth. The 64 hydrophone groups of the array were equally spaced. The site was characterized by an average sediment thickness of 25 m. Water depth was 5000 m permitting time separation of arrivals having different numbers of bottom bounces. A slope density function was constructed partially from seabeam measurements at the site and partially from documented deeptow measurements at other Pacific thin sediment sites. Predictions of omni- and beam-formed time series and an angle spread function were calculated and compared with the data. Results show that the observed long coda and large angle spreads may be predicted by the long non-Gaussian tails of the slope density function.
Bispectral analysis of ocean volume reverberation.
Authors: Alexandrou Dimitri , Premus Vincent
Published: October 2005

The univariate probability density function (pdf) of the volume reverberation process is typically modeled as symmetric and non-Gaussian, with a variable kurtosis parameter. However, very little is known about the joint distribution of volume reverberation. In this study, the bispectral analysis of actual ocean volume reverberation data is performed in an effort to gain more insight into the structure of the joint probability density function of the volume reverberation process. The test vehicle is the Hinich test, a statistical method based on the sample bispectrum, which can be used to quantify the degree of non-Gaussianity and asymmetry in the joint pdf of a random process. Simulated data records, distributed χ2 with decreasing numbers of degrees freedom, are first examined to provide a baseline measure of test statistic behavior as a function of pdf asymmetry. The test is then applied to actual volume reverberation data records obtained using seabeam. Although the empirically determined univariate density function for each seabeam data record exhibits a very high degree of symmetry, the Hinich test statistic indicates the presence of a large degree of asymmetry in the joint pdf of the volume reverberation process.
Source localization in an uncertain scattering environment.
Authors: Haralabus G. , Premus V. , Alexandrou D. , Nolte L. W. , Richardson A. M.
Published: October 2005

The sensitivity of conventional matched-field processing algorithms to uncertainty in environmental parameters has prompted the design of more robust methods for source localization. Recently, the development of a new algorithm, the optimum uncertain field processor (OUFP), was reported which incorporates, apriori, the environmental uncertainty into the design of the matched-field processing algorithm [A. M. Richardson and L. W. Nolte, J. Acoust. Soc. Am. 89, 2280–2284 (1991)]. The processor was demonstrated to successfully locate a source in a deep ocean environment for the case of an uncertain sound velocity profile. The present study addresses the problem of source localization in a shallow-water channel, in which the received pressure field consists primarily of bottom and surface interacting rays. Surface and bottom roughness are parametrized by the Eckart reflection coefficient. Environmental uncertainty is then introduced through mismatch in the reflection coefficient. Initial simulation results demonstrate that, when scattered rays constitute a significant portion of the received pressure field, the OUFP outperforms the conventional matched-field processor when the actual reflection coefficient is imperfectly known.
Seismic conversion of low-frequency surface-generated ambient noise in the deep ocean.
Authors: Schmidt H. , Liu J-Y. , Kuperman W. A.
Published: October 2005

The strong increase in ambient noise observed at low frequencies (1–10 Hz) in shallow water can be explained by the strong excitation of seismic interface or Scholte waves by surface sources in this frequency regime [H. Schmidt and W. A. Kuperman, J. Acoust. Soc. Am. 84, 2153–2162 (1988)]. There is strong experimental evidence that a similar increase observed in deep water is also due in part to the excitation of Scholte waves [Dorman etal., J. Acoust. Soc. Am. 89, 1905–1906 (1991)]. However, here the separation of the surface and bottom is too large to allow for direct coupling of surface-generated noise into the evanescent seismic waves. Here, the hypothesis that the Scholte waves are excited through rough interface scattering of the surface generated noise is investigated. By combining the Schmidt–Kuperman noise model with a perturbation formulation for three-dimensional scattering by rough interfaces in the bottom [W. A. Kuperman and H. Schmidt, J. Acoust. Soc. Am. 86, 1511–1522 (1989)], it is demonstrated that rough interface scattering can account for a significant part of the observed increase in noise level at the seabed. In addition it is shown that the spatial coherence predicted by this model is consistent with the experimental observations. [Work supported by ONR and NOARL.]
Long-term 0.05–5 Hz ambient deep-ocean noise, wind, and ocean waves.
Authors: McCreery Charles S. , Duennebier Frederick K. , Walker Daniel A. , Schroeder Thomas A.
Published: October 2005

Long-term ambient ocean noise data from the Wake Island hydrophone array in the northwest Pacific are compared to wind measured at Wake and to ocean wave estimates near Wake from U.S. Navy models. Between 0.05 and 0.1 Hz, the hydrophone data are limited by system noise, although long-period signals from moderate to large earthquakes often exceed that limit. From 0.1 to 0.2 Hz, the ambient noise correlates well with the estimated long-period ocean swell, with about a 2.5:1 correspondence in their respective frequencies−close to the 2:1 correspondence predicted by nonlinear wave interaction theory. Between 0.2 and 0.3 Hz, the most energetic part of the noise spectrum, the correlation with ocean waves is weaker, suggesting that this noise may have its origin at a more distant location. Between 0.3 and 1 Hz, the noise again correlates strongly with the estimated ocean waves, although the frequency correspondence is 5:1 or greater. And from 1 to 5 Hz, the ambient noise correlates very strongly with windspeed and exhibits a saturation that probably corresponds to the saturation of short wavelength ocean wind waves. Based on hourly measurements made over a 4-yr period, ambient noise levels between 0.1 and 2 Hz vary by less than 20 dB, 90% of the time. Between 2 and 5 Hz, noise levels are found to be saturated more than 70% of the time.
Simultaneous observations of acoustic scattering and ocean microstructure in the arctic.
Authors: Plueddemann Albert J. , Padman Laurie , Stanton Timothy P. , Sherman Jeffrey T. , Pinkel Robert
Published: October 2005

Intriguing new observations from an ice camp, manned during the Cooperative Eastern Arctic Experiment (CEAREX) on the Northwest flank of the Yermak Plateau, indicate that ocean microstructure may be detectable with ‘‘standard’’ acoustic instrumentation (i.e., acoustic Doppler current profilers) of moderately high frequency (150–300 kHz). The strength of the CEAREX data set is the simultaneous observation of kinetic energy dissipation rate, temperature dissipation rate, and acoustic backscatter from both 160- to 300-kHz Doppler profilers. The turbulence levels observed during CEAREX were particularly strong (ε≳10−7 W kg−1) and occurred in well-defined patches. Backscattered intensity anomalies of 2 to 6 dB were found to be coincident in time and space with patches of strong turbulence in the thermocline. It is shown that the acoustic intensity anomalies co-vary with the strength of the turbulent dissipation above a threshold that presumably represents the background particulate scattering level. Theoretical predictions of the acoustic intensity level based on the microstructure measurements are used to support the hypothesis that the enhanced scattering levels are due to temperature anomalies.
Acoustic emissions of toroidal bubbles.
Authors: Kolaini Ali R. , Nicholas Michael , Crum Lawrence A.
Published: October 2005

Toroidal bubbles can be formed by injecting a small volume of air impulsively through a nozzle placed underwater. As the air leaves the nozzle, the front face (which is initially moving with a large velocity) slows down within a short distance and time, and a jet of air moving from the back of the bubble at high speed then penetrates the front face, thus forming a toroidal bubble. These bubbles then move upwards with their plane perpendicular to the direction of motion. The ring radius increases while the cross-sectional area of the air core decreases; simultaneously, the fluid velocity on the surface of the toroid slows down due to viscous effects. The combination of these two effects causes the toroidal bubbles eventually to become unstable and to break into a number of small bubbles. This phenomenon can be observed for a number of conditions. During the formation of the toroid, low-frequency, relatively high-amplitude damped acoustic emissions were observed, with a shift to higher frequencies as a function of time. During toroid breakup, a number of bubbles within a fairly narrow size distribution were observed which emitted sound at higher frequencies and lower amplitudes than the toroid-formation sound. In this presentation some preliminary results are shown of the acoustic emissions of toroidal bubbles formed using a variety of nozzle diameters, air injection velocities and air volumes. [Work supported by ONR and ONT.]
Optical detection of transient bubble oscillations associated with the underwater noise of rain.
Authors: Stroud John S. , Marston Philip L.
Published: October 2005

It is known that for a drop of water falling on a water surface a bubble will be entrained for certain drop diameter-impact velocity combinations [Pumphrey etal., J. Acoust. Soc. Am. 85, 1518–1526 (1989)]. Due to the small size of the entrained bubble, the frequency of oscillation (near 14 kHz), and the very small oscillation amplitude, it is extremely difficult to view the volume pulsations of the newly created bubbles. Such oscillations contribute to the underwater noise of rain. A method was developed for optical detection of these oscillations. The entrained bubble is in the path of a laser beam when the bubble is created. The beam was then directed to a photodetector and the transient signal resulting from oscillations of the optical cross section of the bubble was recorded. This optically obtained record was compared to an acoustic record of the same event (obtained by using a hydrophone). The two records agree remarkably well in both time and frequency. The general magnitude of the initial radial oscillation is estimated and compared with theoretical results by H. N. Oguz and A. Prosperetti [J. Fluid Mech. 228, 417–442 (1991)]. [Work supported by ONR.]
Broadband low-frequency sound radiator with high-frequency pump resonator.
Authors: Donskoy Dimitri M.
Published: October 2005

A new type of underwater low-frequency radiator is described. Operation of the radiator is based on the nonlinear conversion of high-frequency acoustic pump energy to low-frequency sound pulsation of the water volume of the open acoustic pump resonator. High-intensity pump waves in the resonator produce cavitation. Water containing bubbles is highly nonlinear (hundreds and even thousands of times more than pure water), and dispersive. Both of these factors, and also the use of the pump resonator, promote much stronger conversion of pump energy to low-frequency sound in comparison with a parametric radiator. The calculation of the acoustical characteristics is presented.
Monterey Bay acoustic environmental monitoring system.
Authors: Lashkari Khosrow , Denner Warren W. , Miller James , Chiu Ching Sang
Published: October 2005

Over the past few decades sound has been used with increasing success to measure and monitor a variety of oceanographic features and processes−biological populations, water structure, internal waves, bathymetry, and climatic change to name just a few. Monterey Bay and surrounding ocean regions have recently been proposed as a Marine Sanctuary. Scientists see this region as a natural marine laboratory. In an effort to unobtrusively monitor features and processes in this ocean region a group of local scientists have initiated the design of an Acoustic Environmental Monitoring System (AEMS). A preliminary design meeting was held 28–29 February 1992 by a group of interested scientists and engineers at the Monterey Bay Aquarium. This paper reports on the preliminary design and objectives of the AEMS based on that meeting. The AEMS will consist of three monitoring sites within Monterey Bay, one near the head of Monterey Canyon, and two on the adjacent shelf areas. The sites will be connected to shore by high bandwidth telemetry links. Each site will consist of an instrumentation platform, with quick connect sensor mountings. While acoustic instrumentation will constitute the backbone, the monitoring systems will have provisions to support other oceanographic instruments. Hardware and software interface standards will be established for accommodating these sensors. The acoustic instrumentation will consist of hydrophone arrays, projectors, and acoustic Doppler current meters.

The intent is to provide a long-term monitoring capability and a test bed for a variety of environmental monitoring systems. Some of the initial objectives for the AEMS are: provide a long-term acoustic research facility available to the civilian scientific community; provide a reception site for global-warming experiments and other long-range ocean propagation research; monitoring activity in the Marine Sanctuary; marine mammal research; monitoring geological processes; ocean circulation and water column processes. The purpose in presenting this paper at the May 1992 meeting of the Acoustical Society of America is to gain input to this ambitious project from the largest gathering of knowledgeable scientists and engineers possible.
The parabolic moment equations−Has their promise been fulfilled?
Authors: Uscinski B. J.
Published: October 2005

The parabolic equations for moments of a wave field in a weak random medium are attractively simple. They are linear second-order partial differential equations of the diffusion equation type. They involve the random medium only in terms of its two-point correlation, and most importantly they are mutually independent, so no closure condition is needed. In practice these equations have proved very difficult to solve. Despite the very solid results that have been obtained there are almost as many unresolved difficulties. A full solution has been found for the second moment at a single frequency, but it cannot naturally include the case of a curving ray path in anisotropic scattering irregularities. The cross-frequency second moment describes pulse spread, but closed solutions exist only for certain types of correlation functions. Solutions for the fourth moment tend to break down in the cross-frequency case. Attempts to solve equations for the higher moments have so far failed completely, leaving the question of the probability distribution still open. Despite these difficulties, however, the parabolic moment equations still offer one of the best vehicles for exploring wave propagation in random media.
Stochastic modeling of bottom scattering.
Authors: Jackson Darrell R.
Published: October 2005

Several basic issues arise in stochastic modeling of bottom scattering. Most models predict the mean intensity (a second moment) in terms of an interface scattering cross section per unit area. The cross section is defined under asymptotic conditions, e.g., the transmitter and receiver are infinitely distant, the propagation medium is homogeneous, and time-harmonic excitation is assumed. The key question is the following: When is the cross section thus defined applicable to realistic conditions? Even when the cross section is of no use, the second moment may still have utility, particularly if the scattered field obeys Gaussian statistics. Data are available at high frequencies showing both Gaussian and non-Gaussian behavior of the backscattered field [Chotiros etal., J. Acoust. Soc. Am. 77, 975–982 (1985)]. In the case of low-frequency bottom scattering, the division of bottom topography into large scales (to be treated deterministically) and small scales (to be treated stochastically) is an important issue. Here one must consider acoustic, geological, and practical criteria in making the division.
Modal decomposition of operational response measurements in a multi-source environment.
Authors: Gilheany John J. , Warwick David C.
Published: October 2005

An approach is developed combining experimental modal analysis with operational deflection measurements to determine the contributions of individual modes to the response of a structure subjected to multiple uncorrelated sources. Singular value decomposition is applied to measured cross spectral functions to decompose the response measurements into contributions associated with each significant source. A modal decomposition is then performed on fully coherent deflection patterns associated with each source. The modal participation due to each source in the total response is determined. Damping and natural frequency estimates from the modal analysis are used to determine the generalized force inputs to each mode from each source. Finally, by constraining possible degrees of freedom, estimates of the excitation force vectors associated with each source are made. To demonstrate the approach, standard experimental modal analysis techniques are applied to frequency response functions generated via a numerical model. The results are then combined with numerical simulations of both single and multi-source response measurements to obtain the modal participation spectra. These results are further reduced to determine the generalized forces and physical force vectors associated with each source.
Resonant vibrations of fluid-loaded plates. Two-dimensional case.
Authors: Kauffmann Christiaan
Published: October 2005

Vibrational properties of hull plates of ships are considerably modified by the presence of the water. A simple model problem, consisting of a thin, transversely vibrating plate with a compressible fluid at one side, is analyzed in some detail. The model equations are solved by means of a Green integral representation along with a set of coupled boundary integral equations. The kernel of the integral representation is found by using the Fourier integral transform technique and by evaluating numerically the inverse transform in the complex wave-number plane. For the two-dimensional case the boundary integral equations degenerate to a system of algebraic equations, thus yielding an exact representation of the solution. Numerical results are presented that show the fluid-loading effect on the resonant frequencies of the plate, which are shifted downwards relative to the in-vacuo natural frequencies, while acoustic radiation contributes to the sampling of the plate’s resonant modes. [Work supported by the TNO Institute of Applied Physics, Delft, The Netherlands.]
Interactive coordination of articulation and prosody in Japanese: A chronotopographic observation of laryngeal EMG.
Authors: Honda Kiyoshi , Yoshida Yukinari , Kakita Yuki
Published: October 2005

It is widely accepted that the cricothyroid (CT) plays a predominant role in accentual rise of F0 while the strap muscle, particularly the sternohyoid (SH), exhibits a supplementary function in F0 fall. Antagonistic activity has often been observed between these muscles in typical Japanese accent types. However, the activity of SH is usually less consistent with F0 of overall utterances, mainly because the strap muscle is also involved in articulatory control for jaw opening. Therefore, the interaction should be observed between articulatory and prosody controls. This study is aimed at examining the coordination of jaw articulation and prosody production in Japanese words, using a noninvasive technique to record EMG from the CT and the strap. The signals from arrays of miniature surface electrodes attached on the neck surface are processed to form a chronotopographic EMG, i.e., the place versus time display of neck surface electrical potential. The EMG of the CT is extracted by removing signals from the superficial muscles. The activity of the SH either to lower F0 or to lower the jaw tends to vary with overall F0 of utterances: the SH becomes active when the utterance is produced in low F0. The results suggest a complicated relationship between jaw articulation and prosody control: SH activity and the degree of jaw opening are slightly reduced when high F0 is maintained due to sandhi, and F0 rise tends to be suppressed at jaw lowering in some accent kernels of focused words.
Modeling a leaky glottis.
Authors: Cranen Bert , Schroeter Juergen
Published: October 2005

During the last decade, awareness has grown that the glottis does not necessarily close completely during normal phonation. To what extent a glottal leak affects the glottal flow waveform, however, is still poorly understood. A speech production model is implemented that is capable of simulating source/tract interaction using a time-varying glottal impedance analogous to that in the two-mass glottal model of Ishizaka and Flanagan. The original formulas are extended to incorporate two different types of glottal leakage: (1) a leak that is in open connection with the membranous part of the glottis, and (2) a leak formed by a separate duct (e.g., in the posterior commissure). However, instead of letting the glottal geometry be defined by a self-oscillating mechanical model of the vocal folds, the glottal inlet and outlet areas are prescribed by the authors. In the present simulations it is found that for a moderate leak area the flow through a type 2 leak and the flow through the membranous part may be in opposite directions during the interval that the folds close, thus enhancing the excitation of the vocal tract. Another interesting consequence of this result is that a physical explanation might be given for some of the waveform details sometimes observed in inverse filtered speech that are often considered as artifacts of the inverse filtering method.
Effects of RLN and SLN stimulation on glottic area.
Authors: Bielamowicz Steven A. , Berke Gerald S. , Watson Deborah , Ming Ye
Published: October 2005

In vivo canine experiments have demonstrated that vocal fold stiffness varies proportionately with changing levels of recurrent laryngeal nerve (RLN) and superior laryngeal nerve (SLN) stimulation. This study evaluates the morphologic changes in the glottis at varying levels of nerve stimulation and the effects on laryngeal resistance. Stroboscopic data from the invivo canine model were examined under varying conditions of RLN and SLN stimulation. Computerized analysis of stroboscopic images was used to reconstruct the glottic area versus time waveforms and the results will be presented. Glottal dynamics were measured using photoglottography, electroglottography, and the glottal area waveforms. The effects of varying RLN and SLN stimulation on laryngeal resistance will be discussed. [Work supported by an American Laryngologic Research Award.]
Measurements of mucosal wave propagation and vertical phase difference in vocal fold vibration.
Authors: Titze Ingo R. , Jiang Jack J. , Hsiao Tzu-Yu
Published: October 2005

Examination of surface wave properties in the vocal fold mucosa is becoming an important part of assessment of vocal function. A key wave property is propagation velocity, which determines the phase delay between upper and lower margins of the vocal folds. Excised canine larynges were used in this study to measure this phase delay, and therewith propagation velocity. The motion of two fleshpoints was tracked stroboscopically. Differential displacements between the fleshpoints were matched to displacements of a model. A least-squared fit of the data to the model provided the numerical values of propagation velocity, which varied from 0.5 m/s to about 2.0 m/s, depending on fundamental frequency. The corresponding phase delay along the medial surface of the vocal folds varied from about 60°/mm to 30°/mm. [Work supported by NIDCD, Grant No. P60-DC0976.]
Aerodynamics of phonation: Effect of consonantal context on vowels.
Authors: McGowan Richard S. , Koenig Laura L. , Löfqvist Anders
Published: October 2005

Recordings of oral airflow have been made of four subjects producing VCV sequences with different middle consonants and an open vowel. The flow signals at vowel offset and onset have been inverse filtered using a software inverse filter and characterized as a function of time using measures of maximum flow, minimum flow, open quotient, and area of the glottal pulse. Results suggest that the aerodynamic properties of the source differ considerably among vowels following different consonants. For example, at the onset of a vowel following a voiceless stop or fricative, the source typically shows a breathy pattern of vibration, as evidenced by high values of peak flow and an open quotient close to 1; the source then changes gradually into a modal type of phonation. These variations can be explained by different observed patterns of coordination between the larynx and the oral articulators. The present study reports experimental data and simulations of such dynamic patterns of source variations using a two-mass model of the vocal folds incorporated into a low-frequency model of the vocal tract’s aerodynamics. [Work supported by NIH.]
Vibration and acoustic response of a ribbed plate excited by a line or point force.
Authors: Juang Ten-Bin , Pate Anna L. , Flatau Alison B.
Published: October 2005

An analytic formulation for the vibrational and acoustic responses caused by application of a point or a line force to the rib of a single-ribbed, infinite plate with negligible fluid loading has been investigated previously by the same authors [‘‘Vibrational and Acoustic Response of a Ribbed Infinite Plate Excited by a Force Applied to the Rib,’’ Proc. 2nd Int. Congress on Recent Developments in Air and Structure-Borne Sound and Vibration, March 1992]. An expression for the same responses of ribbed plate system due to similar excitation away from the rib was formulated. Numerical solutions were obtained by using the same technique as before. The results again show that the structural intensity in the ribbed plate is an excellent tool for force and rib localization. Acoustic radiation patterns between the previous case of force on the rib and the present case of force away from the rib are quite different as shown in 3-D pattern results. Moreover, the interaction between force and rib plays an important role in the plate’s vibrational and acoustic responses.
The vibroacoustic response of a laminated plate to a line excitation.
Authors: Hwang Y. F. , Zoccola P. J. , Kim M.
Published: October 2005

This paper discusses a mathematical formalism for numerical calculations of the vibration and acoustic responses of a fluid-loaded laminated plate to a line excitation. The fluid loading may apply to either or both sides of the composite plate that may consist of any arbitrary number of layers of different materials. Numerical examples are presented for the acoustic radiation from the wetted surface of a soft-cored sandwich plate subjected to a line force on its dry side. Detailed analysis on the wave propagation in the layers and effects of material damping are also discussed.