bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adaptation and recovery from adaptation in single fiber responses of the cat auditory nerve
Authors: Chimento Thomas C. , Schreiner Christoph E. 
Published: October 2005

This study examined the time course of adaptation and recovery from adaptation of single auditory-nerve fiber responses. The conditions studied were: (1) adaptation response using low level, 800 Hz or characteristic frequency (CF) stimuli; and (2) onset recovery and whole tone response recovery of a probe tone following a masker of equal frequency with variable silent intervals between the masker offset and probe onset. Single unit responses to 290 ms long, 800 Hz or CF tones presented at 10–30 dB SL were recorded from the auditory nerve of the cat. Adaptation properties were determined and fit to the equation: A(tp)=Yre(−tp/τRr) +Yse(−tp/τRs)+Ass. Recovery from adaptation was determined by recording the response of a probe tone following a 100-ms masker tone equal in frequency to the probe, and with amplitudes ranging from 20- to 30-dB relative to the probe amplitude. Both the onset recovery and the whole tone recovery were determined for the single unit responses.
The onset data were analyzed and fit to either the equation: A(Δxt,tp)=Ass −Yre(−tp/τRr) −Yse(−Δt/τRs) or A(Δt,tp)=Ass−Yre(−Δt/τR). The whole tone response showed two distinctive time patterns that could be fit to either an adaptation equation or to the two-time-constant recovery equation, depending on the relative amplitude of the masker and the length of the silent interval between masker offset and probe onset. The results of this study indicate that single fiber time constants are comparable to those measured in previous studies using the auditory-nerve neurophonic (ANN). Likewise, the pattern of recovery of the whole tone response for single fiber responses is comparable to the ANN. Possible sites and mechanisms for adaptation and recovery from adaptation taking into account recent data from electrical stimulation studies and receptor channel morphology and kinetics are discussed.
Evaluation of simple models of auditory profile analysis using random reference spectra
Authors: Kidd Gerald , Mason Christine R. , Uchanski Rosalie M. , Brantley Merry A. , Shah Phalguni 
Published: October 2005

This article describes further study of the finding reported by Green et al. [J. Acoust. Soc. Am. 73, 639–643 (1983)] and others that, in certain conditions, the threshold of detectability for an intensity increment to the center tone of a multitone reference spectrum decreased as the number of nonsignal tones increased. That result was considered remarkable since critical-band theory would predict that these nonsignal tones, spaced outside the ‘‘critical band’’ containing the signal, would have no effect on or, at most, slightly decrease within-band detectability—and certainly could not account for the result of improved detectability found in the study cited above. Recently, Henn and Turner [J. Acoust. Soc. Am. 88, 126–131 (1990)] were unable to replicate the result described above, concluding that the phenomenon exists only in ‘‘limited conditions’’ and that it is ‘‘highly individual’’ in nature. Further, they speculated that the most likely reason for the discrepancy between their study and previous studies was the selection and/or training of the observers. The present study addressed the effects of the amount of subject training on the finding of Green et al. while controlling the potential effects of stimulus order. Specifically, for a group of three ‘‘naive’’ listeners, thresholds were measured for 3-, 7-, and 21-tone inharmonic complexes as a function of the amount of practice in a mixed-block design.
In all cases the group mean thresholds decreased as the number of nonsignal tones increased both initially and after extensive practice for both fixed- and roving-level conditions. Thus the effect does not appear to be an artifact of the amount or order of training subjects receive. The possible role of subject sample size and the magnitude of individual differences in obtaining the effect remains an open question. Two hypotheses suggested to account for the improvement in threshold with increasing number of nonsignal tones were evaluated. The hypotheses were represented by simple mathematical models, referred to as the ‘‘multiple-comparison’’ and ‘‘pitch-cue’’ models. The predictions of both models were compared with the results of a series of detection experiments in which the independent variables were the number of nonsignal tones and amount of random, within-trial ‘‘amplitude perturbation’’ [cf. Kidd et al., J. Acoust. Soc. Am. 79, 1045–1053 (1986)] of the nonsignal tones. Neither model, as applied, provided a satisfactory account of the effects of the main variables of number of tones and amount of perturbation. Finally, the results provided qualified support for the explanation offered by Kidd et al. [J. Acoust. Soc. Am. 86, 1310–1317 (1989)] that the lack of improvement in signal threshold with increasing noise bandwidth found in a tone-in-noise paradigm resulted from limits on performance imposed by the spectral variability of the random noise.
On the sufficiency of compound target specification of isolated vowels and vowels in /bVb/ syllables
Authors: Andruski Jean E. , Nearey Terrance M. 
Published: October 2005

It has been suggested [e.g., Strange et al., J. Acoust. Soc. Am. 74, 695–705 (1983); Verbrugge and Rakerd, Language Speech 29, 39–57 (1986)] that the temporal margins of vowels in consonantal contexts, consisting mainly of the rapid CV and VC transitions of CVC’s, contain dynamic cues to vowel identity that are not available in isolated vowels and that may be perceptually superior in some circumstances to cues which are inherent to the vowels proper. However, this study shows that vowel-inherent formant targets and cues to vowel-inherent spectral change (measured from nucleus to offglide sections of the vowel itself) persist in the margins of /bVb/ syllables, confirming a hypothesis of Nearey and Assmann [J. Acoust. Soc. Am. 80, 1297–1308 (1986)]. Experiments were conducted to test whether listeners might be using such vowel-inherent, rather than coarticulatory information to identify the vowels. In the first experiment, perceptual tests using ‘‘hybrid silent center’’ syllables (i.e., syllables which contain only brief initial and final portions of the original syllable, and in which speaker identity changes from the initial to the final portion) show that listeners’ error rates and confusion matrices for vowels in /bVb/ syllables are very similar to those for isolated vowels. These results suggest that listeners are using essentially the same type of information in essentially the same way to identify both kinds of stimuli.
Statistical pattern recognition models confirm the relative robustness of nucleus and vocalic offglide cues and can predict reasonably well listeners’ error patterns in all experimental conditions, though performance for /bVb/ syllables is somewhat worse than for isolated vowels. The second experiment involves the use of simplified synthetic stimuli, lacking consonantal transitions, which are shown to provide information that is nearly equivalent phonetically to that of the natural silent center /bVb/ syllables (from which the target measurements were extracted). Although no conclusions are drawn about other contexts, for speakers of Western Canadian English coarticulatory cues appear to play at best a minor role in the perception of vowels in /bVb/ context, while vowel-inherent factors dominate listeners’ perception.
Waveform inversion for the geoacoustic parameters of the ocean bottom
Authors: Rajan Subramaniam D. 
Published: October 2005

The geoacoustic properties of ocean sediments in deep water environments are important parameters necessary to predict low-frequency acoustic fields in the water column. A full wave method for obtaining the geoacoustic parameters from the acoustic field measured as a function of range with a cw source is presented. By assuming horizontal stratification, the unknown geoacoustic parameters are reduced to functions of one variable, i.e., depth. The problem of estimating the geoacoustic properties of the ocean floor is then cast as a parameter estimation problem in which a cost function φ(m), where m is a vector containing the unknown parameters, is minimized. This problem is then solved using a nonlinear optimization algorithm. This algorithm requires the determination of the derivative ∂φ/∂m. For a fluid bottom model an efficient algorithm for obtaining these partial derivatives is presented. The performance of the inversion algorithm is studied using noise free and noisy synthetic data. These inversions are carried out using the complex pressure field and the magnitude of the field as data. For the noise-free case, both approaches yield estimates close to the true value.
In the case of noisy data, inversions carried out using the magnitude of the pressure field as data do not perform as well as inversions where the data are the complex pressure field. However, in both cases the algorithm is stable. The effect of modeling errors on the estimates is studied and it is shown that even small errors in source/receiver location lead to significant errors in the estimates. The effect of modeling the sediment as a fluid on the estimation of its geoacoustic properties is studied. In the case where the sediment shear speed is much smaller than compressional wave speed, the fluid approximation has no significant effect on the estimate of the compressional wave speeds. On the other hand, if the shear speed is such that considerable conversion exists, the fluid bottom model leads to a poor estimate of the compressional wave speed. In both cases the estimates of compressional wave attenuation and density are significantly affected by the fluid approximation. Finally this method is applied to data obtained in a field experiment and an estimate of the compressional wave speed profile in the sediment layers is obtained. This result is compared with the model obtained by iteration of forward models [G. V. Frisk et al., J. Acoust. Soc. Am. 80, 591–600 (1986)].
Transient analytic and numerical results for the fluid–solid interaction of prolate spheroidal shells.
Authors: Jones-Oliveira Janet B. 
Published: October 2005

A transient solution is presented that models the fluid–solid interaction of a thin elastic prolate spheroidal shell loaded end-on by a nonconservative acoustic shock wave. Solutions to the Lagrangian equations of motion are provided for the normal and tangential shell displacement fields, as well as for the incident, scattered, and radiated fluid pressure fields. The temporally and spatially dependent shell displacement and fluid pressure fields are expressed modally in terms of an orthonormal basis that is selected specifically to satisfy the kinematic boundary conditions at the fluid–solid interface identically. Further, the modal representations for the shell displacements resolve the boundary conditions imposed by the problem configuration; and the modal representations for the fluid field satisfy causality. The solutions are developed in terms of prolate spheroidal angular and radial wave functions. For both analytic and computational reasons, the shell displacement and fluid pressure fields are ultimately expressed in terms of Legendre polynomials and modified spherical Bessel functions of the first and third kinds. The resulting solutions are exact within the limit of series solutions. A novel analytic/numerical hybrid solution technique is introduced for solving the inhomogeneous coupled PDE’s; the spectral method is a Galerkin variation. The explicit analytic solutions converge to the exact solution of the actual coupled differential equations over the entire temporal and spatial domains both in the structure and in the fluid.
Series truncation is postponed until the final expressions and their mathematical structure are known, thereby ensuring that all relevant physics has been correctly modeled having taken full advantage of inherent symmetries. Numerical results for the free vibrations and for the transient fluid–solid interactions of a fluid-loaded prolate spheroidal shell are presented. Specifically, the axisymmetric in-vacuo nondimensionalized frequencies are tabulated for three characteristic cases corresponding to low, intermediate, and high aspect ratio geometries. The fluid loading is shown to shift the frequencies, as well as introduce additional structural frequencies. Plots of the shell displacements, velocities, accelerations, strains, and strain rates are presented for the submerged shock-loaded low aspect ratio case. Insights into the qualitative and quantitative effects of the fluid on the structural response are revealed. DOE-macsyma was used extensively to develop and verify the solutions to this problem. [This work was performed under the auspices of DOE by LLNL under Contract No. W-7405-Eng-48.]
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.
Characterization of cardiovascular tissue with ultrasonic backscatter.
Authors: Wickline Samuel A. , Perez Julio E. , Barzilai Benico , Sobel Burton E. , Miller James G. 
Published: October 2005

Quantitative characterization of cardiovascular tissue with backscattered ultrasound has evolved from a laboratory tool to a clinical adjunct for conventional echocardiographic imaging. Integrated backscatter imaging was developed by our laboratory to permit analysis of the physical properties of myocardial tissue independent of wall motion or chamber dimension. Initial observations in experimental animals and later in patients revealed that normal myocardium exhibits a cardiac cycle-dependent alteration in the intensity of backscatter that reflects intrinsic myocardial contractile performance. Detection of blunted cyclic variation of backscatter has been used by this laboratory and others to delineate regional contractile dysfunction in patients with infarction, ‘‘stunned’’ myocardium, cardiomyopathy (idiopathic and diabetic), hypertension, and cardiac transplant rejection. Automated ventricular boundary detection is another recent clinical application based on integrated backscatter imaging that allows on-line display and tracking of cavity edges throughout the cardiac cycle in either transthoracic or transesophageal imaging modes to define global ventricular performance.
Another recent clinical innovation, ‘‘lateral gain compensation,’’ permits quantification of and compensation for the ultrasonic anisotropy of scattering exhibited by myocardial tissue, which is attributable to a highly ordered and complex arrangement of myofibers. Promising novel developments for tissue characterization include determination of the frequency dependence of scattering, which may improve the specificity for echocardiographic diagnosis of acute infarction and cardiomyopathy and facilitate quantification of pathologic tissue architectural remodeling. [Work supported by NIH Grant Nos. HL42950, HL40302, HL17646.]
The relationship between behavioral and auditory brainstem response thresholds in infants and adults.
Authors: Werner Lynne A. , Rickard Mancl Lisa , Folsom Richard C. 
Published: October 2005

It has been previously reported [L. A. Werner etal., J. Acoust. Soc. Am. Suppl. 1 88, S18 (1990)] that for 3-month-old infants, there is a modest but significant correlation between detection thresholds measured behaviorally and using the auditory brainstem response (ABR) for tone pips at 4 and 8 kHz, but not at 1 kHz. It has been hypothesized that one should not see a correlation between behavioral and ABR thresholds among young normal-hearing adults, since variability in hearing levels in this group would be small, and that as infants’ thresholds approached those of adults (around 6 months of age), the correlations we observed at 3 months would decrease. In the current study, detection thresholds were obtained from 20 to 30 yr olds at 1, 4, and 8 kHz and from 6-month olds at 8 kHz using behavioral and ABR measures to test these hypotheses. The stimuli were tone pips with 2-cycle rise and fall and no steady state. ABR thresholds were measured by reducing the level from 20 dBnHL until no response was observed, then increasing the level until the response reappeared. Behavioral thresholds were estimated adaptively, and defined as the average of the last 8 reversals obtained.
For infants, a trial was considered ‘‘correct’’ if an observer said ‘‘yes’’ when a signal was presented to the infant, or ‘‘no’’ when no signal was presented. The observer had no prior knowledge of trial type. Adults were instructed to respond whenever they heard the tone pips. The correlation between ABR and behavioral threshold for adults was not significant at 1 or 4 kHz. Similarly, there was no correlation between the two measures for 6-month olds at 8 kHz. The correlation between ABR and behavioral thresholds for adults was significant, however, at 8 kHz. These findings suggest that variability associated with development of the auditory system is responsible for the ABR-behavioral threshold correlation seen at young ages. [Work supported by NIH DC00520.]
The role of envelope fluctuations in an apparent demonstration of suppression in simultaneous masking
Authors: Wright Beverly A. 
Published: October 2005

Fastl and Bechly [J. Acoust. Soc. Am. 74, 754–757 (1983)] reported that the threshold of a brief 900-Hz signal simultaneously masked by a band of noise, 100 Hz wide, centered at 1000 Hz, was reduced by approximately 8 dB by the addition of an 1150-Hz tone having a level of 20 dB above that of the narrow-band masker. They concluded that this decrease in threshold was a demonstration of suppression in simultaneous masking. Here it is argued that Fastl and Bechly’s results simply reflect the poorer detectability of signals masked by higher-frequency fluctuating maskers (their narrow-band masker) than by relatively flat-envelope maskers (their composite narrow-band plus tonal masker). The results of three experiments support the masker-envelope explanation. In the first experiment, as in the report of Fastl and Bechly, the masker centered at 1000 Hz (M1) was a narrow-band noise and the masker centered at 1150 Hz (M2) was a tone. Fastl and Bechly’s result was replicated. However, thresholds obtained when M1 was presented alone (the M1-only condition) were more affected by the starting level of the signal within each adaptive track than were thresholds obtained when M1 and M2 were presented together (the M1+M2 condition). This result paralleled a previous report that starting level influenced performance more with fluctuating than with flat-envelope maskers.
For the four of seven subjects who showed learning, there was also more improvement in the M1-only than in the M1+M2 condition. In the second experiment, M1 was a tone and M2 was a narrow-band noise. Thresholds were higher in the M1+M2 than in the M1-only condition, presumably due to the increased masker fluctuations in the M1+M2 condition. Finally, in the third experiment, there was little or no difference in threshold in the M1-only and M1+M2 conditions for the majority of subjects when M1 and M2 were both tones. Caution is advised in interpreting a release from masking as suppression. The failure to demonstrate suppression in simultaneous masking for the majority of subjects, using an off-frequency signal and stimuli relatively free of the confounding influence of envelope fluctuations, is in contrast to a prediction that suppression in simultaneous masking should be revealed if the masker and signal have different frequencies and thus are not equally influenced by the suppression effect.