bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic radiation due to the inelastic impact of a sphere on a rectangular plate
Authors: Troccaz Philippe , Woodcock Roland , Laville Frédéric
Published: July 2002

Impact between two structures is an important source of noise in industry. However, it is not a well-known phenomenon from a theoretical point of view. The models available in the literature for impact noise often address only part of the phenomenon. In this paper, a more comprehensive model is developed. The acoustic radiation due to the inelastic impact of a sphere with a rectangular simply supported thin plate is formulated and validated experimentally. The impact force is calculated from Hertz’s law, which has been extended to the case of plastic deformations, and the acoustic radiation in the time domain is obtained using Rayleigh’s integral, the plate being discretized in rectangular elements. The model is used to show that the sound-radiation mechanism includes two separate sources: the initial deformation of the plate and the propagation of the bending waves. The model is also used to determine the contribution to impact noise of parameters that characterize the two impacting structures or the impact configuration such as plasticity, damping, materials, and impact velocity.
A phenomenological model for the responses of auditory-nerve fibers: I. Nonlinear tuning with compression and suppression
Authors: Zhang Xuedong , Heinz Michael G. , Bruce Ian C. , Carney Laurel H.
Published: July 2002

A phenomenological model was developed to describe responses of high-spontaneous-rate auditory-nerve (AN) fibers, including several nonlinear response properties. Level-dependent gain (compression), bandwidth, and phase properties were implemented with a control path that varied the gain and bandwidth of tuning in the signal-path filter. By making the bandwidth of the control path broad with respect to the signal path, the wide frequency range of two-tone suppression was included. By making the control-path filter level dependent and tuned to a frequency slightly higher than the signal-path filter, other properties of two-tone suppression were also included. These properties included the asymmetrical growth of suppression above and below the characteristic frequency and the frequency offset of the suppression tuning curve with respect to the excitatory tuning curve. The implementation of this model represents a relatively simple phenomenological description of a single mechanism that underlies several important nonlinear response properties of AN fibers. The model provides a tool for studying the roles of these nonlinearities in the encoding of simple and complex sounds in the responses of populations of AN fibers.
Semi-analytical elastic wave-field modeling applied to arbitrarily oriented orthotropic media
Authors: Spies Martin
Published: July 2002

Three-dimensional elastic wave-field calculation is addressed for the case of orthotropic materials with arbitrary spatial orientation. Based on a mathematical formulation involving Green’s dyadic displacement tensor function, appropriate evaluation yields a representation of the displacement vector of transducer wave fields in anisotropic media which is convenient for effective numerical computation. With respect to bulk wave propagation, the numerical evaluation of Green’s dyadic function is circumvented by applying a reciprocity-based approach, which is valid in the (point source) far field. The presented formulation involves characteristic quantities obtained from plane-wave theory and appears as a point-source superposition representation including the respective point-source directivities. Thus, it is in the same form as a corresponding formulation for scattered elastic wave fields presented previously [M. Spies, J. Acoust. Soc. Am. 107, 2755–2759 (2000)]. Focusing on orthotropic composite materials, numerical evaluation examples are presented for ultrasonic tranducer field patterns and time-dependent radio frequency (rf)-pulse propagation.
Evaluation of impulse noise criteria using human volunteer data
Authors: Chan Philemon C. , Ho Kevin H. , Kan Kit K. , Stuhmiller James H. , Mayorga Maria A.
Published: July 2002

Four impulse noise auditory injury criteria adopted by NATO countries, namely, the MIL-STD-1474D (USA), Pfander (Germany), Smoorenburg (Netherlands), and LAeq8 (France), are evaluated against human volunteer data. Data from subjects wearing single-hearing protection exposed to increasing blast overpressure effects were obtained from tests sponsored by the US Army Medical Research and Material Command. Using logistic regression, the four criteria were each correlated with the test data. The analysis shows that all four criteria are overly conservative by 9.6–21.2 dB for the subjects as tested. The MIL-STD-1474D for single-hearing protection is 9.6 dB lower than the observed injury threshold for 95% protection with 95% confidence for this particular group of subjects as tested. Similar conclusions can be drawn for the other three criteria.
Lumped-element technique for the measurement of complex density
Authors: Petculescu A. , Wilen L. A.
Published: July 2002

A novel lumped-element technique is employed to measure the complex density of a gas in circular pores. The complex density expresses the geometry-dependent viscous coupling between the gas and the pore walls and is related to the thermoacoustic function fμ, or equivalently, F(λV). The acoustic impedance of a compliant region coupled to a pore (or pore-array) is measured and the impedance of the compliant region is subtracted to yield the impedance of the pore(s) alone, which is directly related to F(λV). Pores of different lengths are measured in order to eliminate end effects. Working down to very low frequencies achieves a wide range of values for the ratio of the viscous penetration depth to the mean pore size. The results agree very well with analytical solutions for circular pores. The technique is also applied to two porous foam materials. Comparing the results to previous measurements of the complex compressibility, it is shown that two different shape factors (or equivalently, characteristic dimensions) are required to account for the data.
Research into an integrated intelligent structure— A new actuator combining piezoelectric ceramic and electrorheological fluid
Authors: Quanlu Li
Published: July 2002

The design, preparation, and application of high-performance piezoelectric ceramics, e.g., FD3–PZT and FD4–PZT, then preparation, performance measurement, and applications of composite electrorheological fluids have been studied, respectively. The integrated intelligent structure (i.e., a new actuator) combining the piezoelectric ceramic and the electrorheological fluids, and their applications have been investigated, and emphasis was given to the applications in acoustics and vibration control, etc. as may be noted.
Scattering by a fluid cylinder in a porous medium: Application to trabecular bone
Authors: Luppé Francine , Conoir Jean-Marc , Franklin Hervé
Published: July 2002

In a trabecular bone, considered as a nondissipative porous medium, the scattering of an incident wave by cylindrical pores larger than the wavelength is studied. The goal is to know if scattering alone may cause such a high attenuation as that observed in calcaneus. The porous medium is modelized via Biot’s theory and the scattering by a single pore is characterized from the definition of a scattering matrix. An approximation of weakly disordered medium is then discussed to estimate the effective attenuation and dispersion as a function of frequency. These effective properties are shown to be different of those measured on calcaneus, due to the neglect of wave conversions during the scattering process.
Frequency dependence of broadband propagation in coastal regions
Authors: Badiey M. , Simmen J. , Forsythe S.
Published: July 2002

To study the frequency-dependent spatial and temporal variabilities of sound propagation in coastal regions two experiments were conducted by transmitting sound impulses in the form of M sequences centered from 0.6 to 22 kHz. The site of the first experiment was the Atlantic Generating Station (AGS) where the source–receiver range was 214 m. The site of the second experiment was Delaware Bay where the range was approximately 760 m. The mean water depth was 14–15 m in both locations. Oceanographic data and acoustic data were collected simultaneously in both experiments. It was found that the temporal coherence of the propagated broadband signal changes significantly with pulse center frequency, as well as varying with geographic location and time. Trends of increasing signal decorrelation (between consecutive pulses) with increasing center frequency, and increasing signal decorrelation for paths with increasing number of interface interactions, were observed. It was found that for lower center frequencies there is hardly any decorrelation in signal over several hours, while for signals with center frequencies only a few kHz higher there was substantial decorrelation over times as short as 10 to 20 min. No significant spatial decorrelation of the signal was observed over the hydrophone spacing of a few meters for these experiments.
Mechanisms of vowel recognition for Ineraid patients fit with continuous interleaved sampling processors
Authors: Dorman Michael F. , Loizou Philipos C.
Published: July 2002

Vowel recognition was assessed for eight, cochlear implant patients who use the Ineraid’s six-electrode array. Recognition was tested in three conditions: with the Ineraid after years of experience; with a CIS processor at fitting of the processor; and with the CIS processor after 1 month’s experience. At the time of fitting of the CIS processor, vowel recognition was not superior to that with the Ineraid. Recognition improved significantly over the period of a month. At 1 month, performance was significantly better with the CIS processor than with the Ineraid. This outcome is interpreted to mean that remapping of the vowel space is necessary following fitting with the CIS processor and some of the remapping occurs over a time period of days or weeks, rather than hours. Vowel errors at one month could be accounted for by two mechanisms. One is that patients attended to low-frequency channels at the expense of high-frequency channels, or could not use information in high-frequency channels. The second is that, for diphthongs, patients could not detect frequency change over the course of the utterance.
Extraction of a target scattering response from measurements made over long ranges in shallow water
Authors: Sarkissian Angie
Published: July 2002

The scattering response of a structure may be extracted from acoustic measurements made in shallow water at relatively long ranges from the target. The procedure described uses an array of sources to approximately generate a low-order mode and an array of receivers to isolate from the received echo a low-order mode. Since low-order modes behave as plane waves in the vicinity of the target, the free-field target response may be extracted from such measurements. In general, such a procedure for the generation of a low-order mode requires a large number of sources. The number is of the order of the number of propagating, nonevanescent modes present in the shallow water environment at the frequencies used. If this number is prohibitively large, temporal discrimination may be used in addition to beamforming to reduce the number of sources necessary for the isolation of the free-field target response. Similarly, the number of receivers required for the isolation of a mode from the received signal may be reduced by the use of temporal discrimination in addition to beamforming techniques. This article presents the detailed procedure used as well as numerical simulations to demonstrate the feasibility of such a process.
Perceived lateral position of narrow-band noise in hearing-impaired and normal-hearing listeners under conditions of equal sensation level and sound-pressure level
Authors: Simon Helen J. , Aleksandrovsky Inna
Published: July 2002

The perceived lateral position of narrow-band noise (NBN) was studied in a graphic pointer task as a function of the method of compensation for interaural threshold asymmetries in hearing-impaired and normal-hearing subjects. The method of compensation consisted of equal sensation level (EqSL) or equal sound-pressure level (EqSPL) at the two ears within the same subject. The NBN signals were presented at 11 center frequencies with interaural intensity differences (IIDs) that varied from −20 to +20 dB. When equalizing by SL, the perceived lateral position is essentially linearly dependent on the degree and direction of asymmetry in asymmetric normal-hearing and hearing-impaired listeners. Equalizing by SPL shows no such dependency but produces images that are lateralized close to the midline. These results reveal that subjects may have adapted to their threshold asymmetries. These results will be discussed in terms of the fitting of binaural hearing aids.
Perceptual grouping of tone sequences by normally hearing and hearing-impaired listeners
Authors: Rose Marina M. , Moore Brian C. J.
Published: July 2002

This study examined the perceptual grouping of rapid tone sequences for listeners with normal hearing and listeners with unilateral and bilateral cochlear hearing loss. The sequence ABA–ABA–was used, where A and B represent sinusoidal tones bursts (10-ms rise/fall, 80-ms steady state, 20-ms interval between tones) and – represents a silent interval of 120 ms. Tone A was fixed in frequency at 250, 500, 1000, or 2000 Hz. Tone B started with a frequency well above or below that of tone A, and its frequency was swept towards that of tone A so that the frequency separation between them decreased in an exponential manner. Listeners were required to indicate when they could no longer hear the tones A and B as two separate streams, but heard only a single stream with a “gallop” rhythm. This is called the fission boundary. For the normally hearing listeners, the separation between tones A and B at the fission boundary was roughly independent of the frequency of tone A when expressed as the difference in number of ERBs (delta E) between A and B, which is consistent with a recent model of stream segregation [M. W. Beauvois and R. Meddis, J. Acoust. Soc. Am. 99, 2270–2280 (1996)]. For the unilaterally hearing-impaired listeners, there was no consistent difference in the delta E magnitudes across ears, even though the auditory filters were broader in the impaired ears. This is not consistent with the theory of Beauvois and Meddis. The bilaterally hearing-impaired listeners sometimes showed delta E magnitudes within the normal range, and sometimes showed larger than normal delta E magnitudes. The results are discussed in terms of the factors that might influence perceptual stream formation in hearing-impaired listeners.
Distortion product otoacoustic emissions in human newborns and adults. II. Level effects
Authors: Lasky Robert E.
Published: July 2002

This study varied the levels of the primaries and recorded distortion product otoacoustic emissions (DPOAEs) from human newborns and adults. Preterm as well as term newborns were tested. The 2 f1−f2 DPOAE was the most reliably recorded DPOAE, especially at low levels of the primaries. Amplitude and phase reproducibility deteriorated with decreasing level of the primaries. Newborn DPOAEs were slightly less reproducible than adult DPOAEs. The underlying DPOAE I/O functions were nonmonotonic for both newborns and adults. Unity gain characterized the initial increasing portion of those functions in most subjects. Although newborn and adult I/O functions were similar, they did differ. In particular, adult functions tended to be more linear with saturation at higher primary levels. Some of the newborn functions saturated at very low stimulus levels. Although differences in cochlear mechanics may explain developmental difference in DPOAE I/O functions, developmental differences in the resonance characteristics of the outer and middle ears may also be involved.
Growth behavior of the 2 f1−f2 distortion product otoacoustic emission in tinnitus
Authors: Janssen Thomas , Kummer Peter , Arnold Wolfgang
Published: July 2002

High-resolution hearing threshold and 2 f1−f2 distortion product otoacoustic emission (DP) were measured with the same in-the-ear sound probe and same calibration at 51 frequencies between 500 and 8000 Hz in 39 sensorineural hearing loss ears associated with tinnitus. Using a primary tone setting L1=0.4L2+39 that accounts for the nonlinear interaction of the two primary tones at the DP generation site at f2, DPs were elicited in a wide range from L2=65 to 20 dB SPL. We failed to find a uniform DP behavior in the 39 tinnitus ears tested. Seventeen of them behaved like impaired ears without tinnitus. In these ears a linearized DP growth was observed where the DP level decreased and the slope of the DP I/O functions steepened with increasing hearing loss and as a result both the DP level and the DP slope strongly correlated with hearing threshold. The other population, 22 tinnitus ears, exhibited a poor or even inverse relationship between DP level and hearing threshold, i.e., displayed an increase of DP level with increasing hearing loss. Despite the severe hearing loss but due to the high level, DPs could be recorded well in the frequency range that corresponded to the appearance of the tinnitus. The DP slope, however, increased with increasing hearing loss and, therefore, did still correlate with hearing threshold revealing pathological alteration. The data suggest that the DP level alone is hardly capable of assessing hearing impairment in tinnitus ears and may even be misleading. Thus just the DP slope seems to be the only reliable indicator of cochlear malfunction around the tinnitus frequency. The observed nonuniform DP behavior suggests different cochlear impairments in tinnitus ears. In those ears where the DP level decreases and the slope of the I/O functions increases with hearing loss, cochlear sensitivity and tuning are supposed to be diminished. In those ears where the DP level increases with increasing hearing loss, a reinforced mechanical distortion is hypothetized to be generated by cochlear hyperactivity that can be the source of both the abnormally high DP level and the tinnitus.
Differentiation of cochlear pathophysiology in ears damaged by salicylate or a pure tone using a nonlinear systems identification technique
Authors: Bian Lin , Chertoff Mark E.
Published: July 2002

Mongolian gerbils were exposed to either α-ketoglutarate, salicylate, or an 8-kHz pure tone. Cochlear microphonic (CM) was recorded from the round window in response to 68 and 88 dB SPL Gaussian noise. A nonlinear systems identification technique provided the frequency-domain parameters of a third-order polynomial model characterizing cochlear mechano-electric transduction (MET). A series of physiologic indices were derived from further exploration of the model. Exposure to the 8-kHz pure tone and round window application of salicylate resulted in different changes in the polynomial parameters and physiologic indices even though the threshold shifts were similar. A general reduction of CM magnitude was found after the tone exposure, and an increase at low-mid frequencies was demonstrated in the salicylate group especially at the lower signal level. The slope of the MET curve was reduced by the acoustic overstimulation. The root or the operating point of the MET was shifted in opposite directions after the two treatments. Sound-pressure levels that saturate MET expanded in the tone exposure group and narrowed in the salicylate group. The signal level also had effects on these indices.
Ground effect over hard rough surfaces
Authors: Boulanger Patrice , Attenborough Keith , Taherzadeh Shahram , Waters-Fuller Tim , Li Kai Ming
Published: July 2002

Laboratory and outdoor measurements are reported of the relative sound pressure level spectrum over hard surfaces containing either random or periodically spaced arrays of 2-D roughnesses. The resulting data have been compared with predictions obtained analytically and with numerical predictions of a boundary element code. Effective impedances of the rough surfaces have been calculated from the boss theory developed by Twersky. A classical asymptotic approximation for propagation near grazing incidence from a point source over an impedance boundary has been modified, heuristically, to allow for diffraction grating effects. The resulting predictions are found to be in tolerable agreement with the data except for close and random packing. The boundary element code is found to give superior results for larger roughnesses, but computational restrictions on element size reduce its usefulness for roughnesses with small width or height.
Guided waves’ propagation in an elastic plate of linearly varying thickness
Authors: Guillet Arnaud , Ech Cherif El Kettani Mounsif , Luppe Francine
Published: July 2002

Experimental studies of guided waves propagating in an elastic plate of linearly decreasing thickness are presented. The plate is embedded in water, and the mode’s excitation is achieved by means of an ultrasonic beam at a given incident angle. Measurements are done either with a receiving transducer or with a laser interferometer. In the first case, the amplitude of the leaking wave and its reemission angle are measured, while, in the second case, the normal acoustic displacement at the surface of the plate is obtained. Use of the surface wave analysis method then provides the dispersion curves of the propagating waves. For plates of small thickness slopes (one or two degrees), the interface waves are shown to behave mostly as generalized Lamb waves which adapt continuously to the varying thickness as they propagate. Evidence of waves propagating backward before having reached the plate end is shown. Mode’s conversions also occur, giving rise to intermodes’ branches in the dispersion plane.
Sound localization in noise in normal-hearing listeners
Authors: Lorenzi Christian , Gatehouse Stuart , Lever Catherine
Published: July 2002

The ability to localize a click train in the frontal–horizontal plane was measured in quiet and in the presence of a white-noise masker. The experiment tested the effects of signal frequency, signal-to-noise ratio (S/N), and masker location. Clicks were low-pass filtered at 11 kHz in the broadband condition, low-pass filtered at 1.6 kHz in the low-pass condition, and bandpass filtered between 1.6 and 11 kHz in the high-pass condition. The masker was presented at either −90, 0, or +90 deg azimuth. Six signal-to-noise ratios were used, ranging from −9 to +18 dB. Results obtained with four normal-hearing listeners show that (1) for all masker locations and filtering conditions, localization accuracy remains unaffected by noise until 0–6 dB S/N and decreases at more adverse signal-to-noise ratios, (2) for all filtering conditions and at low signal-to-noise ratios, the effect of noise is greater when noise is presented at ±90 deg azimuth than at 0 deg azimuth, (3) the effect of noise is similar for all filtering conditions when noise is presented at 0 deg azimuth, and (4) when noise is presented at ±90 deg azimuth, the effect of noise is similar for the broadband and high-pass conditions, but greater for the low-pass condition. These results suggest that the low- and high-frequency cues used to localize sounds are equally affected when noise is presented at 0 deg azimuth. However, low-frequency cues are less resistant to noise than high-frequency cues when noise is presented at ±90 deg azimuth. When both low- and high-frequency cues are available, listeners base their decision on the cues providing the most accurate estimation of the direction of the sound source (high-frequency cues). Parallel measures of click detectability suggest that the poorer localization accuracy observed when noise is at ±90 deg azimuth may be caused by a reduction in the detectability of the signal at the ear ipsilateral to the noise.
Target strength of an oily deep-water fish, orange roughy (Hoplostethus atlanticus) I. Experiments
Authors: McClatchie Sam , Macaulay Gavin , Coombs Roger F. , Grimes Paul , Hart Alan
Published: July 2002

Target strengths (TS) of orange roughy (Hoplostethus atlanticus) are difficult to measure in situ because this species lives at 800–1200 m, has low TS at 38 kHz, shows strong avoidance behavior, and sometimes co-occurs with species having much higher TS. Orange roughy have wax-invested swimbladders and fish are ∼20% wax esters by weight. Estimates of orange roughy near-dorsal aspect tilt-averaged target strength (〈TS〉) are controversial, varying from [−39, −35] dB to [−52, −48] dB for a 35-cm fish in different studies. 〈TS〉 is estimated using experiments on both live and dead fish, and new swimming orientation data. Target strength of previously frozen and thawed fish decline rapidly, stabilizing after ∼12 h as air and oil diffuse out of tissues during rehydration. A 〈TS〉 of −46.3 dB is predicted for a 35-cm live orange roughy (bootstrapped 95% confidence intervals=−48.0 to −45.5 dB). This value is 3.7 dB higher than Australian estimates of ≈−50 dB for 〈TS〉 of a 35-cm live orange roughy. It is shown that the magnitude of the difference between in situ estimates of 〈TS〉 and experimental measurements of 〈TS〉 on live fish can be explained by the effect of strong avoidance reactions to a towed transducer on the tilt angle of the fish. Previously much higher estimates of dead orange roughy 〈TS〉 were an artifact of air pockets caused by freezing. Comparison of orange roughy TSmax measured in our experiments with a large dataset for nonswimbladder and swimbladder fish shows that orange roughy have an unusually low target strength at 38 kHz.
A minimum-variance frequency-domain algorithm for binaural hearing aid processing
Authors: Lockwood Michael E. , Jones Douglas L. , Elledge Mark E. , Bilger Robert C. , Goueygou Marc , Lansing Charissa R. , Liu Chen , O’Brien William D. , Wheeler Bruce C.
Published: July 2002

A new algorithm has been developed that allows optimal filtering methods to be applied individually to different narrow frequency bands. Using this technique it is possible to process binaural signals in a manner which dramatically reduces the amplitude of signals originating away from a desired receive direction. The algorithm was tested on artificially combined anechoic and reverberant signals with varying numbers of interfering sound sources. In addition to being computationally efficient, the algorithm was able to produce output which had a consistently positive intelligibility weighted SNR gain [Link and Buckley, J. Acoust. Soc. Am. 91, 1662 (1992)], and in which the desired talker was noticeably easier to understand. Results of a paired-comparison listening test confirmed these results, and allowed an estimate to be made of the algorithm parameters which provided the best speech intelligibility for the output. These parameters included the window length, length of a filtered block, and amount of data which must be stored in memory. Collectively, the results show that this algorithm may be the first building block for a binaural hearing-aid processing algorithm which suppresses off-axis interference. [Research supported by the Beckman Institute.]
The influence of musical training on the perception of sequentially presented mistuned harmonics
Authors: Burns Edward M. , Houtsma Adrianus J. M.
Published: July 2002

The question of whether musical scales have developed from a processing advantage for frequency ratios based on small integers, i.e., ratios derived from relationships among harmonically related tones, is widely debated in musicology and music perception. In the extreme position, this processing advantage for these so-called “natural intervals” is assumed to be inherent, and to apply to sequentially presented tones. If this is the case, evidence for this processing advantage should show up in psychoacoustic experiments using listeners from the general population. This paper reports on replications and extensions of two studies from the literature. One [Lee and Green, J. Acoust. Soc. Am. 96, 716–725 (1994)] suggests that listeners from the general population can in fact determine whether sequentially presented tones are harmonically related. The other study [Houtgast, J. Acoust. Soc. Am. 60, 405–409 (1976)] is interpreted in different terms, but could be confounded by such an ability. The results of the replications and extensions, using listeners of known relative pitch proficiency, are consistent with the idea that only trained musicians can reliably determine whether sequentially presented tones are harmonically related.
Hybrid geoacoustic inversion of broadband Mediterranean Sea data
Authors: Fallat Mark R. , Nielsen Peter L. , Dosso Stan E.
Published: July 2002

This paper describes an acoustic experiment (PROSIM’97) carried out to investigate inversion for seabed properties at a site off the west coast of Italy where previous acoustic and geophysical studies have been performed. Acoustic fields were measured at a vertical hydrophone array due to a swept-frequency source towed over weakly range-dependent bathymetry. Based on the known geology, the seabed is modeled as a sediment layer overlying a semi-infinite basement with unknown model parameters consisting of the sediment thickness, sediment and basement sound speeds, source range and depth, water depth at the source and array, and array tilt. A hybrid inversion algorithm is applied to determine the model values that minimize the mismatch with the measured acoustic fields. Multiple data sets are analyzed to examine the consistency of the inversion results. It is found that the low sound speed of the sediment layer, together with a large uncertainty in bathymetry, leads to strong correlations between the water depths and sediment thickness. This precludes reliable estimation of these parameters individually; however, the total depth to the basement can be estimated reliably. In addition, the basement speed and geometric parameters are estimated consistently, and all parameters compare favorably with the geophysical ground-truth information and with previous inversion results.
Integration of monaural and binaural evidence of vowel formants
Authors: Akeroyd Michael A. , Summerfield A. Quentin
Published: July 2002

The intelligibility of speech is sustained at lower signal-to-noise ratios when the speech has a different interaural configuration from the noise. This paper argues that the advantage arises in part because listeners combine evidence of the spectrum of speech in the across-frequency profile of interaural decorrelation with evidence in the across-frequency profile of intensity. To support the argument, three experiments examined the ability of listeners to integrate and segregate evidence of vowel formants in these two profiles. In experiment 1, listeners achieved accurate identification of the members of a small set of vowels whose first formant was defined by a peak in one profile and whose second formant was defined by a peak in the other profile. This result demonstrates that integration is possible. Experiment 2 demonstrated that integration is not mandatory, insofar as listeners could report the identity of a vowel defined entirely in one profile despite the presence of a competing vowel in the other profile. The presence of the competing vowel reduced accuracy of identification, however, showing that segregation was incomplete. Experiment 3 demonstrated that segregation of the binaural vowel, in particular, can be increased by the introduction of an onset asynchrony between the competing vowels. The results of experiments 2 and 3 show that the intrinsic cues for segregation of the profiles are relatively weak. Overall, the results are compatible with the argument that listeners can integrate evidence of spectral peaks from the two profiles.
Temporary shift in masked hearing thresholds of bottlenose dolphins, Tursiops truncatus, and white whales, Delphinapterus leucas, after exposure to intense tones
Authors: Schlundt Carolyn E. , Finneran James J. , Carder Donald A. , Ridgway Sam H.
Published: July 2002

A behavioral response paradigm was used to measure masked underwater hearing thresholds in five bottlenose dolphins and two white whales before and immediately after exposure to intense 1-s tones at 0.4, 3, 10, 20, and 75 kHz. The resulting levels of fatiguing stimuli necessary to induce 6 dB or larger masked temporary threshold shifts (MTTSs) were generally between 192 and 201 dB re: 1 μPa. The exceptions occurred at 75 kHz, where one dolphin exhibited an MTTS after exposure at 182 dB re: 1 μPa and the other dolphin did not show any shift after exposure to maximum levels of 193 dB re: 1 μPa, and at 0.4 kHz, where no subjects exhibited shifts at levels up to 193 dB re: 1 μPa. The shifts occurred most often at frequencies above the fatiguing stimulus. Dolphins began to exhibit altered behavior at levels of 178–193 dB re: 1μPa and above; white whales displayed altered behavior at 180–196 dB re: 1 μPa and above. At the conclusion of the study all thresholds were at baseline values. These data confirm that cetaceans are susceptible to temporary threshold shifts (TTS) and that small levels of TTS may be fully recovered.
Error analysis of a practical energy density sensor
Authors: Parkins John W. , Sommerfeldt Scott D. , Tichy Jiri
Published: July 2002

The investigation of an active control system based on acoustic energy density has led to the analysis and development of an inexpensive three-axes energy density sensor. The energy density sensor comprises six electret microphones mounted on the surface of a 0.025-m (1 in.) radius sphere. The bias errors for the potential, kinetic, and total energy density as well as the magnitude of intensity of a spherical sensor are compared to a sensor comprising six microphones suspended in space. Analytical, computer-modeled, and experimental data are presented for both sensor configurations in the case of traveling and standing wave fields, for an arbitrary incidence angle. It is shown that the energy density measurement is the most nearly accurate measurement of the four for the conditions presented. Experimentally, it is found that the spherical energy density sensor is within ±1.75 dB compared to reference measurements in the 110–400 Hz frequency range in a reverberant enclosure. The diffraction effects from the hard sphere enable the sensor to be made more compact by a factor of 23 compared to the sensor with suspended microphones.
Cavitation in Viscoelastic Media
Authors: Kaelble D. H.
Published: July 2002

A theoretical model for cavitation in viscoelastic media is developed which incorporates both interfacial and rheological arguments. The properties of interfacial and bulk cavities are correlated, and the influence of time-dependent cavity vapor pressure Pν(t) or hydrostatic tension σ̄(t) are correlated with the extension ratio λ=r/r0 of the cavity surface in a stress relaxation model. Experimental data are analysed for cavitation by peeling, tensile loading of butt joints, and superheating of swollen elastomers. For each case an agreement between theory and experiments is obtained which identifies the specific mode of cavitation and indicates for all cases the presence of prenucleated cavities with radii r0⩾1.0 microns. The direct correlation of peeling stresses with viscoelastic restraints to interfacial cavitation provides a new type of experimental confirmation for the applicability of rate-temperature superposition to peeling data. The implicit assumption that the interfacial failure stress depends upon frequency or strain rate in the same fashion as cohesive failure stress is confirmed by cavitation theory for the general case where surface tension constraints are negligible compared to viscoelastic constraints.
Characterization of the rheological properties of a fast-curing epoxy-molding compound
Authors: Han Sejin , Wang K. K. , Hieber C. A. , Cohen C.
Published: July 2002

The viscosity of an epoxy-molding compound (EMC) has been characterized using a parallel-plate viscometer and a specially-developed slit rheometer. In particular, steady-state and dynamic viscosities at low temperatures and shear rates have been determined with a parallel-plate viscometer. Measurements with this instrument indicate that an extended Cox–Merz relation can be used to relate the dynamic viscosity to the steady shear viscosity for the given EMC. For measurements at high shear rates and high temperatures, a special slit rheometer has been built. In this viscometer, the slit is preceded by a disk-shaped reservoir where curing of the specimen takes place. The sample fills the thin reservoir fast and has its temperature raised by heat conduction from the hot wall. Because the reservoir is thin, the specimen quickly reaches the wall temperature with negligible cure and then cures under approximately isothermal conditions. The degree of cure of the sample is measured by quenching the specimen as it is extruded out of the slit and then performing differential-scanning-calorimeter measurements. By combining results from these two viscometers, the viscosity of the EMC has been obtained over the typical processing range of shear rates, temperature and degree of cure encountered during chip encapsulation. The measurement results indicate that the EMC viscosity exhibits a yield-stress behavior at low shear rates and a power-law behavior at high shear rates. The temperature dependence can be described by the WLF (Williams–Landel–Ferry) equation and the degree-of-cure dependence at low cure by an equation proposed by Macosko.
A thermodynamically admissible reptation model for fast flows of entangled polymers
Authors: Öttinger Hans Christian
Published: July 2002

The primary purpose of this paper is to introduce the effect of chain stretching into a previously developed, thermodynamically admissible reptation model incorporating anisotropic tube cross sections, double reptation, and convective constraint release, while avoiding the independent alignment approximation. A second goal is the detailed illustration of the thermodynamic modeling approach. Two versions of the model with different stretching mechanisms are proposed, and the simpler one sheds new light on thermodynamically admissible reptation models without independent alignment. The stochastic reformulation of the new model, its simulation, its linear viscoelastic properties, its predictions for rapid double-step shear strains, and the model parameters are discussed in detail.
Association of Allostatic Load With Overall Mortality Among Patients With Metastatic Non–Small Cell Lung Cancer
Authors: Obeng-Gyasi Samilia , Li Yaming , Carson William E. , Reisinger Sarah , Presley Carolyn J. , Shields Peter G. , Carbone David P. , Ceppa DuyKhanh P. , Carlos Ruth C. , Andersen Barbara L.
Published: July 2022

Importance

Adverse social determinants of health (SDHs) (eg, poverty) are associated with poor oncologic outcomes among patients with lung cancer. However, no studies have evaluated biological correlates of adverse SDHs, operationalized as allostatic load (AL), with mortality due to lung cancer.

Objective

To examine the association among AL, SDHs, and mortality among patients with metastatic non–small cell lung cancer (NSCLC).

Design, Setting, and Participants

This cross-sectional study of an observational cohort was performed at a National Cancer Institute–designated comprehensive cancer center with data accrued from June 1, 2017, to August 31, 2019. Patients with metastatic (stage IV) NSCLC enrolled at diagnosis into a prospective observational cohort study were included in the present analysis if they had all the biomarkers to calculate an AL score (N = 143). Follow-up was completed on August 31, 2021, and data were analyzed from July 1 to September 30, 2021.

Exposures

Social determinants of health.

Main Outcomes and Measures

Overall mortality and AL.

Results

A total of 143 patients met the study criteria with a median age of 63 (IQR, 55-71) years (89 men [62.2%] and 54 women [37.8%]). In terms of race and ethnicity, 1 patient (0.7%) was Asian, 7 (4.9%) were Black, 117 (81.8%) were White, 17 (11.9%) were of multiple races, and 1 (0.7%) was of other race or ethnicity. The mean (SD) AL was 2.90 (1.37). Elevated AL covaried with lower educational level (r = −0.26; P = .002), male sex (r = 0.19; P = .02), limited mobility (r = 0.19; P = .04), worsening self-care (r = 0.30; P < .001), problems engaging in usual activities (r = 0.21; P = .01), depressive symptoms (r = 0.23; P = .005), and a high number of stressful life events (r = 0.30; P < .001). Multivariable analysis found only increasing difficulty with mobility (r = 0.37 [95% CI, 0.13-0.60]; P = .002) and male sex (r = 0.63 [95% CI, 0.19-1.08]; P = .005) associated with higher AL. On adjusted analysis, elevated AL (hazard ratio, 1.43 [95% CI, 1.16-1.79]; P = .001) and low educational level (hazard ratio, 2.11 [95% CI, 1.03-4.34]; P = .04) were associated with worse overall mortality.

Conclusions and Relevance

The findings of this cross-sectional study suggest that higher AL was associated with adverse SDHs and worse overall mortality among patients with advanced NSCLC. These results provide a framework for replication and further studies of AL as a biological correlate for SDH and future prognostic marker.
A Musical Ode
Authors: Rajendran Tara
Published: July 2022

This essay explores the author’s experience with music and medicine.
Persistent Vascular Lesion in a Young Boy
Authors: Lee Tonya , Movaghar Mansoor , Liu Catherine Y.
Published: July 2022

A 3-year-old boy presented with a vascular lesion involving the left orbit and face. A magnetic resonance imaging scan revealed an orbital mass surrounding the left lateral rectus muscle with mass effect on the globe and extension into the eyelid, pterygopalatine fossa, and cheek. What would you do next?
Mycobacterium tuberculosis low molecular weight T‐cell antigen Mtb8.4 has heme‐binding and fiber‐forming properties
Authors: Singh Rashika , Kundu Prasun , Bhattacharje Gourab , Das Amit Kumar
Published: July 2022

Mtb8.4, a secretory T‐cell antigen of Mycobacterium tuberculosis, is important for providing an antigen‐specific immune response. In this study, we showed Mtb8.4 to have both heme‐binding and fibril‐forming properties, using experimental and in silico methods. High absorbance at 410 nm and interaction with hemin‐agarose demonstrated its heme‐binding nature. Titration of Mtb8.4 with heme resulted in 1 : 1 stoichiometry. The heme‐binding pocket in Mtb8.4 was identified by molecular modeling, and binding residues were predicted using molecular docking. The molecular dynamics simulations of apo‐ and heme‐bound Mtb8.4 confirmed that the heme group forms a stable complex. Transmission electron microscopy analyses and dye‐binding assays showed that Mtb8.4 forms fibers. Computational studies predicted that the C‐terminal sequence (93AAQYIGLVESV103) is important for forming fibers. In silico analyses further anticipated the probable epitope (82AMAAQLQAV90) of Mtb8.4. The fiber‐forming properties of Mtb8.4 could be advantageous from a vaccine perspective for aggregate/fibril‐based vaccine delivery or it might influence the epitope presentation of Mtb8.4.
Efficiency Measurement and Modeling of a High‐Performance Mg2(Si,Sn)‐Based Thermoelectric Generator
Authors: Camut Julia , Ziolkowski Pawel , Ponnusamy Prasanna , Stiewe Christian , Mueller Eckhard , de Boor Johannes
Published: July 2022

Mg2(Si,Sn) is an attractive material class due to its excellent thermoelectric (TE) properties, its eco‐friendly constituents, its low mass density, and its low price. A lot of research has been done on optimizing its TE properties; however, works on its use in thermoelectric generators (TEG) are scarce. Herein, the first conversion efficiency measurement of a functional, fully Mg2(Si,Sn)‐based TEG, approaching a maximum value of 4% for an applied  = 375 °C, is shown. A maximum power density of 0.9 W cm−2 (related to the cross‐sectional area of the TE legs) at =375 °C is also reported, which is among the highest performance of silicide‐based modules reported in literature. Efficiency measurements can be tricky due to the uncertainty of heat flow measurement and parasitic heat losses; therefore, assessing the measurement reliability by confronting it to theoretical calculations is necessary. TEG device simulation in a constant property model is used to compare measured data to expected values and a good match is found (<1% deviation for current at maximum power, <4% difference for maximum power output, deviation within measurement uncertainty range for heat flows and efficiency). The significant discrepancy between measurement and calculations of the inner electrical resistance reveals room for improvement. Cracks form due to thermally induced mechanical stress, which dramatically increase the inner electrical resistance. It is shown that by avoiding those cracks, the maximum power output and conversion efficiency of the TEG could be improved by 30%.
Controlled Formation of Conduction Channels in Memristive Devices Observed by X‐ray Multimodal Imaging
Authors: Liu Huajun , Dong Yongqi , Galib Mirza , Cai Zhonghou , Stan Liliana , Zhang Lei , Suwardi Ady , Wu Jing , Cao Jing , Tan Chee Kiang Ivan , Sankaranarayanan Subramanian K. R. S. , Narayanan Badri , Zhou Hua , Fong Dillon D.
Published: July 2022

Neuromorphic computing provides a means for achieving faster and more energy efficient computations than conventional digital computers for artificial intelligence (AI). However, its current accuracy is generally less than the dominant software‐based AI. The key to improving accuracy is to reduce the intrinsic randomness of memristive devices, emulating synapses in the brain for neuromorphic computing. Here using a planar device as a model system, the controlled formation of conduction channels is achieved with high oxygen vacancy concentrations through the design of sharp protrusions in the electrode gap, as observed by X‐ray multimodal imaging of both oxygen stoichiometry and crystallinity. Classical molecular dynamics simulations confirm that the controlled formation of conduction channels arises from confinement of the electric field, yielding a reproducible spatial distribution of oxygen vacancies across switching cycles. This work demonstrates an effective route to control the otherwise random electroforming process by electrode design, facilitating the development of more accurate memristive devices for neuromorphic computing.
Scaling Laws for Perovskite Nanolasers With Photonic and Hybrid Plasmonic Modes
Authors: Huang Zhen‐Ting , Chen Jia‐Wei , Li Heng , Zhu Yizhi , Cui Qiannan , Xu Chunxiang , Lu Tien‐Chang
Published: July 2022

Surface plasmons exhibit an extraordinary capability to reduce the structural size and improve light−matter interaction. However, for small‐sized plasmonic cavities, the optical diffraction limit makes the near‐field difficult to observe, complicating the analysis of exact lasing characteristics. In this study, a 4f measurement system is used to extract the mode parity from the interference pattern and reconstruct the near‐field of the hybrid plasmonic perovskite nanolasers. In conjunction with other measurements, a series of rigorous methods for determining the exact resonance mode and obtaining the precise lasing characteristics of perovskite nanolasers are described. By applying these methods, the scaling laws for wire‐type hybrid plasmonic perovskite lasers are successfully determined and an appropriate size is selected for achieving outstanding lasing performance with low threshold power consumption and a high group index. These methods can be applied to nanowire plasmon‐based lasers to advance the development of plasmonic devices.