bluuebunny/crossref_metadata_2025 huggingface dataset:
Newborns’ head orientation toward trains of brief sounds
Authors: Clarkson Marsha G. , Swain Irina U. , Clifton Rachel K. , Cohen Kenneth
Published: October 2005

Four experiments assessed the importance of stimulus number, repetition rate, and duration for newborns’ head orientation toward brief sounds and related those parameters to the critical ones found for adults. Infants’ responses to various trains of repeated 14-ms rattle sounds were compared with those to a 10-s rattle sound, known to elicit head orientation. Directional responses did not differ from the standard when rattle bursts were repeated at a rate of 20 per second for 1 s (experiment 1). Responding did differ from the standard and deteriorated to chance levels when either the number of moderately paced (6/s) stimulus bursts was decreased to six or fewer (experiments 2 and 3) or the duration of rapidly repeated (24/s) bursts was shortened to 500 ms (experiments 4A and 4B). These results suggest that newborns’ head orientation depends, in part, upon the number of stimulus bursts and stimulus duration.
Material composition discrimination of cylinders at different aspect angles by an echolocating Dolphin
Authors: Au Whitlow W. L. , Turl Charles W.
Published: October 2005

An echolocating dolphin was trained to discriminate between the material composition of two cylinders oriented at different aspect angles. The two targets for the first task were a hollow aluminum and a hollow stainless steel cylinder of the same dimension. For the second task, the targets were the hollow aluminum cylinder and a cylinder of coral rock aggregates encased in degassed epoxy. The dolphin could discriminate the aluminum and steel cylinders perfectly at aspect angles of 0° and 10° (at 0°, the longitudinal axis of a cylinder was perpendicular to the dolphin). The dolphin had its lowest performance (79% and 81% correct) when the cylinders were at aspect angles of 45° and 90°, respectively. The echoes from the aluminum and steel cylinders were the most similar at 45° and 90° the two angles at which the dolphin’s performance was the lowest. The dolphin performed the second discrimination task between the hollow aluminum and coral rock cylinders almost perfectly, at all aspect angles considered. Differences in the occurrence time and amplitude of highlights along with the duration of the echoes seem to be important cues for discrimination of the cylinders. For a simple discrimination task such as the aluminum and coral rock targets, aspect independent information is available for discrimination at arbitrary aspect angles.
Differential sensitivity to vowel continua in Old World monkeys (Macaca) and humans
Authors: Sinnott Joan M. , Kreiter Nancy A.
Published: October 2005

Previous studies indicate that monkey pure tone frequency discrimination is quantitatively and qualitatively very different from that of humans: Monkey DLs at 1.0 and 2.0 kHz are up to 20 times larger than human DLs, and monkeys DLs increase as sensation level increases, in contrast to human DLs [Sinnott et al., J. Acoust. Soc. Am. 78, 1977–1985 (1985); Sinnott et al., J. Comp. Psychol. 101, 126–131 (1987)]. These results led to an hypothesis that monkey frequency discrimination is more dependent upon “rate” coding than is that of humans. The present study compared monkey and human DLs for formant frequency changes along three synthetic vowel continua /ɪ–i/, /æ–ɛ/, and /ɑ–ʌ/. Here, monkey DLs for formants near 1.0 and 2.0 kHz (32–48 Hz) were only about two to three times larger than human DLs (11–21 Hz), and both monkeys and humans exhibited relatively similar, flat sensation level functions. Taken together, these data indicate that monkey and human frequency discrimination is more similar in the case of a complex vowel stimulus than in the case of a simple pure tone stimulus. Results are discussed in relation to “rate” versus “temporal” coding of tones and vowels in the auditory system.
A two-dimensional curvilinear wavegrid for integration along traveling waves
Authors: Ziv M.
Published: October 2005

A curvilinear grid is constructed for the numerical integration of a wave characteristics formulation, where the independent variables are the two-spatial polar coordinates and the time dimension. The grid is formed by the bicharacteristic curves which represent the space-time location of the wave surfaces. This scheme of integration paths allows the solution to propagate along all existing waves that traverse the solution domain. Without detriment to generality, the wavegrid construction method is developed by considering longitudinal and shear waves with constant speeds of which the speed of the shear waves is the smallest.
Observation and inversion of seismo-acoustic waves in a complex arctic ice environment
Authors: Miller Bruce E. , Schmidt Henrik
Published: October 2005

The propagation of low-frequency seismoacoustic waves in the arctic ice canopy is examined through the analysis of data collected during the 1987 PRUDEX ice camp. Study of the geophone time series generated by under-ice detonations reveals not only the expected longitudinal and flexural waves in the ice plate, but also unexpected horizontally polarized transverse (SH) waves. The travel paths of all three wave types are found to be refracted in the horizontal plane along a known ridge line locally separating the ice canopy into two distinct half-plates of thin first-year ice and thicker multi-year ice. The need to determine both the origin of the SH wave and location of each detonation from the received time series highlights the dramatic superiority of geophones over hydrophones in this aplication. Inversion of the geophone data for the ice sheet’s low-frequency elastic parameters is conducted initially by modeling the ice as a single homogeneous isotropic plate using SAFARI. A modified stationary phase approach is then used to extend SAFARI modeling to invert for the parameters of the two ice half-plates simultaneously. The estimated compressional/shear bulk wave speeds are comparable to previously obtained values; however, the compression/shear attenuation values are up to four times greater than earlier estimates.
Effect of gating the masker on frequency-selective listening
Authors: Dai Huanping , Buus Søren
Published: October 2005

When presented with variable-frequency tones in a continuous random-noise masker, observers detect the most frequently presented tone (the target tone) better than other infrequently presented tones (probe tones). The present paper shows that the detection of the probe tones improves, and detection of the target tone worsens, when the masker is gated a few hundred milliseconds before the signal onset. The results suggest that the observers are led to listen for several bands when the masker is gated.
Leaky Lamb waves in an anisotropic plate. II: Nondestructive evaluation of matrix cracks in fiber-reinforced composites
Authors: Dayal Vinay , Kinra Vikram K.
Published: October 2005

This paper is concerned with the use of leaky Lamb waves for the nondestructive evaluation (NDE) of damage in anisotropic materials such as fiber-reinforced composites. Two fundamental acoustic properties of the material, namely, the wave speed and attenuation have been measured. Stiffness is deduced from the wave speed. The damage mode selected for this study is matrix cracking. As expected, the in-plane stiffness decreases and the attenuation increases with an increase in the linear crack density.
Aeroacoustics of large wind turbines
Authors: Hubbard Harvey H. , Shepherd Kevin P.
Published: October 2005

This paper reviews published information on aerodynamically generated noise from large horizontal axis wind turbines operated for electric power generation. Methods are presented for predicting both the discrete frequency rotational noise components and the broadband noise components, and results are compared with measurements. Refraction effects that result in the formation of high-frequency shadow zones in the upwind direction and channeling effects for the low frequencies in the downwind direction are illustrated. Special topics such as distributed source effects in prediction and the role of building dynamics in perception are also included.
Acoustical characteristics of fortis and lenis consonants in Tyap and Jju.
Authors: McKinney Norris P.
Published: October 2005

The contrast between fortis and lenis consonants in Tyap and Jju of Nigeria must be explained otherwise than as a voicing distinction. The acoustical correlates of this phonological contrast between prevocalic consonants include temporal differences, reported earlier [N. P. McKinney, J. Phon. 18, 255–266 (1990)] and expanded upon in this study, and spectral differences, which are also examined here. Pairs of words differing only in whether the initial consonant was fortis or lenis were produced by two speakers of each of the two languages and were analyzed spectrographically. Transitions to vowels from fortis palatalized consonants were found to start with a higher F2 than those from corresponding lenis consonants. Similarly, transitions from fortis labialized consonants were found to start with a lower F1 and F2 than those from lenis ones. Interdependence of these temporal and spectral characteristics will be discussed.
Seismo-acoustic rough bottom scattering of ambient noise in a stratified ocean.
Authors: Liu Jin-Yuan , Schmidt Henrik
Published: October 2005

A previously developed formulation [J.-Y. Liu and H. Schmidt, J. Acoust. Soc. Am. 89, 2013 (1991)], based on a combination of theories for rough interface scattering in a stratifed medium [W. A. Kuperman and H. Schmidt, J. Acoust. Soc. Am. 86, 1511–1522 (1989)] and for the noise field produced by distributed random sources at the sea surface [W. A. Kuperman and F. Ingenito, J. Acoust. Soc. Am. 67, 1988–1996 (1980)], has been applied to a realistic ocean model to explore the noise field characteristics due to the rough bottom scattering of ambient noise. The scattering mechanism established in the previous study was able to account for the high noise levels in an otherwise ‘‘quiet’’ bottom of an upward refracting deep ocean environment. The intensity and spatial correlation of the overall noise field have been examined. It is demonstrated that the existence of the rough interfaces greatly affects the noise field; in particular, the rescattering of Scholte waves due to roughness accounts for the major scattering energy near the bottom of the ocean, and the rough surface statistics shows a dominant effect on the spatial characteristics of the noise field. [Work supported by NOARL.]
Determination of the complex sound speed of the longitudinal wave of materials using test-panel measurements.
Authors: Giangreco C. , Audoly C.
Published: October 2005

The characteristics of materials for underwater acoustics are frequently evaluated by measuring the complex (modulus and phase) reflection and transmission coefficients of panels with respect to the frequency. Using these measurements, which can be obtained accurately for normal incidence excitation, two methods of determination of the complex sound speed of the longitudinal wave of the tested material are presented here. Both methods use experimental results on the test panel measurements and theoretical expressions. The first one uses the information in a frequency range and can lead to the density, the thickness (which can be useful under hydrostatic pressure measurements), and the complex velocity of the longitudinal wave of the tested material. The second one uses the information at a given frequency and leads only to the complex velocity of the longitudinal wave. The variation of the complex velocity along the frequency in the sonar frequency range can be obtained using these methods. The accuracy of this determination is studied numerically for different kinds of the materials. Experimental results obtained on three test panels confirm the conclusions of the theoretical study. Used as examples were the variations of the speed of sound in P foam and anechoic-like materials in the range 1.5–20 kHz.
Flaw sizing from pulse-echo ultrasonics: A model based approach.
Authors: Cook Bill D. , Johansen Michael
Published: October 2005

Inversion of pulse-echo ultrasonic signals for flaw characteristics requires accounting for the excitation signal of the transducer, transducer characteristics, and diffraction of sound. The approach most often taken is to remove the influence of these factors by deconvolution using a signal obtained by reflecting the ultrasound from a flat surface. This flat surface needs to be located at the same distance from the transducer as the flaw which is a great disadvantage for an arbitrarily located flaw.

This paper suggests an alternate technique in which rather simple time models account for the above influences. The goal is to describe the flaw from its scattering response. Instead of choosing the impulse response, there is a definite advantage of seeking the ‘‘ramp’’ response. The ramp response is defined such that two time derivatives of the ramp response yields the impulse response. The ramp response approximates the ‘‘area profile’’ function of the scatterer. An integral of the area profile function yields the volume of the flaw scatter. The findings show the output (echo) signal from the transducer can be expressed as the sixth time derivative of the convolution of the desired ramp response with the transducer function twice, the radiation function twice, plus the smoothing function due to attenuation, and the excitation pulse. The convolution of the transducer, radiation, and attenuation functions is ‘‘Gaussian’’ in shape. The experimenter has some control over the time width of these discontinuous functions: by choice of thickness of the piezoelectric in the transducer; and, by choosing a transducer so that the scatterer is in the farfield of the transducer. The functions describing radiation and the transducer enter twice as they are involved in transmission of the sound pulse and its reception after being scattered by a flaw. Assuming that the ‘‘Gaussian’’ shaped function is designed to be insignificant, the output contains the sixth derivative of the convolution of the area profile function and the exciting function to the transducer. By exciting the transducer with a well-behaved, narrow Gaussian function of time, the output signal can be deconvolved using the sixth derivative of this Gaussian yielding the desired output, an approximation to the area profile function. In cases where the ‘‘Gaussian’’ shaped function is not insignificant, it can be deconvolved from the above answer, within limits. In this case, the length of the area profile function should not be significantly shorter than the ‘‘Gaussian’’ shaped function.
Comparison of two analyses of the collapse of a long cylindrical bubble.
Authors: Lopez de Cardenas Jorge E. , Finch Robert D.
Published: October 2005

The solution for the collapse of a long cylindrical bubble obtained with a ‘‘semicompressible-fluid’’ model (energy balance method) is compared with Kedrinsky’s solution which is based on a dynamic analysis (with an acoustic approximation). The semicompressible model is based on an approach similar to Rayleigh’s solution for a spherical bubble which assumes an incompressible fluid. The semicompressible model also assumes incompressible fluid, but the energy balance is made in the fluid contained within the acoustic envelope defined by r=ct; the fluid outside this envelope is neglected. The semicompressible model yields good results for the spherical and cylindrical case but not for the plane case. The differences are explained in terms of the velocity field of each case.
A fast parabolic equation method for outdoor sound propagation.
Authors: Gilbert Kenneth E. , Di Xiao , You Chulsoo
Published: October 2005

A Green’s function approach is used to derive a fast parabolic equation (PE) method for atmospheric sound propagation over a locally reacting ground surface. In the absence of a ground surface, the method reduces to the well-known Fourier split-step algorithm. The new method is approximately 100 times faster than existing PE algorithms that use the Crank–Nicolson method. Hence, the new method opens the door to real-time predictions on desktop computers, fast pulse propagation calculations, and three-dimensional calculations. Numerical results from the new PE model are presented and compared to exact calculations, Fast-field calculations, and to PE results computed with the Crank–Nicolson method. [Work supported by NASA.]
Low-frequency sound propagation conditions in a dense sea fog.
Authors: Browning David G.
Published: October 2005

Although sound absorption due to water droplets was shown by Wiener [F. M. Wiener, J. Acoust. Soc. Am. 33, 1200–1205 (1961)] not to be important under average sea fog conditions, it may significantly increase the attenuation of sound under dense or heavy fog conditions. A comparison of propagation conditions is made between normal and dense fogs, for typical fog signal frequencies, using the droplet absorption estimates of Davidson [G. A. Davidson, J. Acoust. Soc. Am. 62, 497–502 (1977)] to determine the resulting impact on detection ranges.
Sound radiation from noncompact vibrating surfaces in motion.
Authors: Wu X.-F. , Akay A.
Published: October 2005

This paper presents an integral formulation for predicting sound radiation from noncompact vibrating surfaces in motion, with the effect of turbulence induced by source convection taken into account. The fluid density fluctuation is shown to be expressible in terms of volume and surface integrals. The volume integral represents the turbulence effect, while the surface integral describes the effect of the unsteady surface force and the surface displacement effect. For a class of special cases in which the Mach number M is nearly constant across the source region such as in a rectilinear motion, the ratio of the contribution of the volume integral to that of the surface integral is proportional to M/(1−MR), where MR is the component of the Mach number in the direction of wave propagating from the source to receiver. Dimensional analyses show that the turbulence effect dominates the sound radiation at high Mach numbers, especially as the Mach number approaches unity. At low Mach numbers, however, the turbulence effect is negligible and the sound field can be determined based on knowledge of acoustic quantities specified on the surface. Numerical examples of sound radiation from transversely and radially oscillating spheres moving rectilinearly at constant subsonic speeds are demonstrated. The acoustic pressures are shown to be greatly enhanced in the forward direction, while suppressed in the reverse direction. The modification of the acoustic pressure distribution also results in sound radiation in the perpendicular direction. [Work supported in part by ONR, NSF, and IMR of Wayne State Univ.]
Physical optics interpretation of forward scattering from infinite cylindrical elastic shells.
Authors: George Jacob
Published: October 2005

While applications of the methods of physical optics to acoustic backscattering have only been partially successful, the results for forward scattering have been much more encouraging. In previous work [J. Acoust. Soc. Am. 89, 1950 (1991); J. Acoust. Soc. Am. Suppl. 1 70, S21 (1981)] it has been shown that Fresnel diffraction provides a good approximation to forward scattering from spherical elastic shells, rigid/soft spheres, and rigid/soft infinite cylinders. In the present work, forward scattering from infinite cylindrical elastic shells is examined. The results are compared with predictions using the Fresnel method and rigid/soft body approximations. The implications of these findings will be discussed.
A statistical study of tongue muscle EMG and vowel formant frequencies.
Authors: Honda Kiyoshi
Published: October 2005

Toward designing a realistic model of the vocal tract to explain transformational processes from motor to acoustic patterns, statistical relationships between activities of several articulatory muscles and vowel formant frequencies were examined. The EMG and acoustic data of Haskins Laboratories obtained during repetitions of /schwa pvp/ word utterances were used to compare the token-to-token variabilities of EMG signals for vowel segments and of vowels formants. A large variability of EMG signals observed for each tongue muscle during repetitions of the identical utterances seems to be compensated for by other muscles or jaw positions to realize small variabilities of formant frequencies. The extrinsic tongue muscles showed various degrees of correlations with vowel formants. The anterior and posterior genioglossus muscles had a high correlation with F1 and F2 for /i/, and they also showed a positive correlation with F0. The hyoglossus and the anterior genioglossus showed a relatively high correlation with F1 and F2 for /a/, even when jaw position data were excluded, but not significant correlation with F0. The observations from further analyses will be discussed in terms of vocal tract length adjustment. [Work supported in part by an NIH grant to Haskins Laboratories.]
Effects of alcohol on speech: I. Durations of isolated words, sentences, and passages in fluent speech.
Authors: Behne Dawn M. , Rivera Susan M. , Pisoni David B.
Published: October 2005

Although the effects of alcohol on speech production have not been widely investigated, previous research has suggested that utterances produced while a talker is intoxicated may be longer than those produced while the talker is sober [e.g., Sobell etal., Folia Phonetica 34, 316–323 (1982); D. B. Pisoni and C. S. Martin, Alcoholism: Clinical Exp. Res. 13, 577–587 (1989)]. As part of a larger investigation of the effects of alcohol on speech, nine talkers were recorded while sober and intoxicated. Talkers produced isolated monosyllabic words, isolated spondees, isolated sentences, and passages of fluent speech. Two questions of utterance duration were addressed: (1) Does alcohol affect the duration of utterances? (2) Does alcohol affect the duration of different utterance types in the same way? The results revealed that isolated sentences and sentences from within passages produced in the intoxicated condition were reliably longer than those produced in the sober condition. However, for isolated monosyllabic words and spondees, utterance durations were not reliably different between the sober and intoxicated conditions. Results are discussed in terms of the effects of alcohol on speech motor control.
Infrequent words are longer in duration than frequent words.
Authors: Whalen D. H.
Published: October 2005

Studies measuring productions of frequent and infrequent words have shown an increased duration for the infrequent items. However, this increase has previously been attributed to anything but word frequency: differences in the number of phonemes, in the duration of the phonemes themselves, in the number of letters in the spelling, in functional load, and even in the pauses between the items. The present study attempted to avoid those interpretations by using high-frequency/low-frequency homophones that are not also homographs (e.g., ‘‘through’’/‘‘threw’’). In this way, the number and type of phonemes were exactly controlled for. In addition, the items were chosen so that the lower frequency word had the same number of letters or fewer, and did not have an exceptional spelling unless the higher frequency word did as well. These items were then produced in a rehearsed, speeded list, where functional load was negligible. Even so, the infrequent items were longer in duration (by about 3% in preliminary measurements). Since identical phonemes strings were uttered, these results suggest that a link to the lexicon is maintained throughout production. [Work supported by NIH Grant DC-00825.]
A stochastic model for scattering from the near-surface oceanic bubble layer.
Authors: Gilbert Kenneth E. , Wang Lintao , Goodman Ralph R.
Published: October 2005

A stochastic scattering model has been developed that allows the backscatter from a subsurface bubble layer to be written as the product of a geometric factor times the horizontal wave-number (‘‘power’’) spectrum of the bubble layer. By dividing the measured backscatter versus frequency data by the geometric factor, one can ‘‘invert’’ the backscatter data and directly infer the horizontal wave-number spectrum of the bubble layer. Three different data sets give power-law wave-number spectra: P(K)≊A‖K‖−β, where β≊4 for two of the data sets and β≊3 for the third data set. The factor A is a constant that is different for each data set. When the inferred wave-number spectrum is used to predict backscatter versus angle, good agreement is obtained with the data at low frequencies and low grazing angles. The consistency in the inferred wave-number spectrum strongly suggests that a systematic power-law spectrum exists for the near-surface oceanic bubble layer. A time-dependent bubble plume model is discussed that shows how a power-law wave-number spectrum can arise in the bubble layer. [Work supported by ONR.]
Rheological studies of surfactant-coated drops in microgravity.
Authors: Apfel Robert E. , Holt R. Glynn
Published: October 2005

Measurement of the rheological properties (viscosity, tension, elasticity) of liquid surfaces and interfaces is a task that is complicated by configuration and unwanted contamination. Acoustic levitation can partially alleviate the configuration and contamination problems by isolating the test fluid as a drop in air or another host liquid. However, the drops are unavoidably deformed from a spherical shape by the intense ultrasonic radiation force required to balance the gravitational force. Use of sonic fields to position drops in a microgravity environment can provide a spherical drop in a contact-free environment, making experiments easier to perform, and enabling comparisons with the solution of theoretical models in which a simple geometry can be assumed. The First United States Microgravity Laboratory (USML-1) mission, which will utilize the shuttle Columbia for a 13-day flight devoted to science, will include experiments designed by our Yale acoustics group to be performed in a dedicated acoustic positioning apparatus called the drop physics model (DPM). The goals of these experiments are: (1) to determine the rheological properties of liquid drops in the presence or absence of surface active materials by exciting single drops into their quadrupole resonance and observing their free decay; and (2) to investigate the mechanisms for coalescence of droplets with and without surfactants using a variety of techniques for perturbation of the interface between the drops. Results from current ground-based experiments and theoretical modeling performed to support the microgravity effort will be presented. Additionally, the flight experiments’ design, implementation, and execution will be discussed, as well as ideas for possible future experiments that would exploit the unique environment that the DPM provides. [Work supported by NASA through JPL Contract 958722.]
Predicting acoustic noise environments on Space Station Freedom using statistical energy analysis.
Authors: Bergen Thomas , Badilla Gloria
Published: October 2005

Noise control is an important design consideration for Space Station Freedom (SSF), both for crew safety and productivity. Crew acoustic noise requirements are established to eliminate fatigue and potential hearing loss from long-term exposure and to facilitate speech communications. The requirements are set at noise criteria (NC) 50 for the work areas, and NC 40 during sleep periods. The noise environments are induced by various sources such as fans, pumps, and other mechanical devices. Prediction of the on-orbit noise environments in the U.S. modules has been performed using the vibroacoustic payload environment prediction system (VAPEPS). VAPEPS is a computer program that utilizes statistical energy analysis (SEA) techniques to predict vibroacoustic environments in complex systems. A VAPEPS model of the habitation module (before reconfiguration) was developed, and various sources were input to the model to predict their effects on the system. Results from the preliminary analysis indicated that acoustic noise requirements would be severely exceeded with the initial scenario of equipment. [Work performed by the Jet Propulsion Laboratory, California Institute of Technology, and sponsored by the National Aeronautics and Space Administration.] a) Gloria Badilla is an employee of SYSCON Corporation under contract to JPL.
Determination of traffic noise barrier effectiveness.
Authors: Herman Lloyd A. , Bowlby William , O’Grady Thomas , Chen Cong
Published: October 2005

This study evaluated the benefits of a noise control program involving construction of over $13 million of traffic noise barriers along Interstate 440 in Nashville, TN. In addition, much of I-440 was depressed in a rock cut with an objective of reducing the traffic noise levels. There were four basic objectives to the study: (1) determine barrier insertion losses at various sites for various geometric configurations; (2) determine change in community noise levels (from before the highway project); (3) study effectiveness of sound-absorbing blocks used on one section to minimize multiple reflections between parallel barriers; and (4) investigate reasons for any differences between predicted and measured insertion losses. Measurements of A-weighted average sound levels and noise reduction were made at over 40 sites. Calibrated predictions of levels without the barriers were also made. Differences in design geometries, terrain, and construction techniques made it impossible to generalize results from one measurement area to the next. The study also afforded the opportunity for a major application and evaluation of the indirect measured and indirect predicted methods in ANSI S12.8-1987, ‘‘American National Standard Methods for Determination of Insertion Loss of Outdoor Noise Barriers.’’
Viscoelastic polymer temperature-frequency shift functions.
Authors: Dewitt Leilani , Reader Wayne T.
Published: October 2005

The frequency and temperature relationships of viscoelastic moduli, in particular, the loss factor and shear or Young’s elastic moduli, can be critical to acoustical damping applications. By practical necessity, these data are collected by varying both temperature and frequency, thereby resulting in a family of curves. Using the equivalence of the effects of frequency and temperature on polymers, that is invoking the principle of time-temperature superposition, numerous shifting techniques have been used to present the moduli as a function of only one variable with the other held constant. This paper compares various shifting techniques that are being used. Advantages and disadvantages of each method are discussed. Methods evaluated include: the popular Williams, Landel, and Ferry (WLF) equation [J. D. Ferry, ViscoelasticPropertiesofPolymers (Wiley, New York, 1970)], a method based on activation energy, an iterative method based on both the shear and loss data [L. Rogers, 60th Shock and Vibration Symposium, Virginia Beach, VA, Nov. 1969], and a newly developed simplified method based only upon the slope of the shear modulus curve.
Attenuation and modulus at low frequencies in a homogeneous, viscoelastic medium : Temperature effects on an acrylic rod.
Authors: Smith Billy J. , Batzle Michael L.
Published: October 2005

For calibration of a low-frequency, broadband device, Young’s modulus (E) and attenuation (1/Qe) were measured for acrylic plastic and compared to resonant beam results. Broadband data yield 1/Qe and E in viscoelastic materials when stress/strain relationships are obtained with bonded strain gages. A sample 2.54 cm in diameter and 4.75 cm in length was measured in the broadband device at amplitudes less than 1 microstrain over the 1- to 2000-Hz frequency range at 23 °C and 40 °C. As the sample heated, E decreased and the 1/Qe peak shifted up in frequency and magnitude. Since fluid-saturated porous materials (e.g., rocks) require pressure isolation, a 0.00254-cm-thick brass jacket was then applied. Jacketed sample behavior was similar, but overall attenuation decreased over the frequency range. Here, 1/Qe and E values coincided with values obtained on a 5.08-cm-diam by 60.95-cm-long sample of acrylic measured in a resonant beam apparatus at 1650 Hz, confirming broadband measurement validity.
Development of the infrastructure of phonological systems.
Authors: Oller D. Kimbrough , Lynch Michael P.
Published: October 2005

Insightful description of infant vocal development requires a framework that allows comparison of the vocal units of infant sounds to a comparable level of structure in mature speech systems. The infrastructure of phonological systems can be accounted for by focusing on essential components of acoustics/articulation of each tier of the natural rhythmic hierarchy of speech. The hierarchy includes at least syllable, foot, line, and verse tiers, all of which can be characterized in terms of essential properties (e.g., allowable durations, resonances, F0 patterns). Having once established the infraphonogical properties of elements at a variety of levels, it is possible to describe infant vocalizations in terms of those properties and to discern important patterns of development in infants−stages of development that correspond to the mastery of different parts of the infrastructural scheme. In addition, in the context of such description, certain key differences in the development of normal and handicapped infants come into focus−deaf infants are severely delayed in the onset of infraphonologically well-formed syllables, Down Syndrome infants are slightly delayed in well-formed syllables, but show major differences from normal infants in the time frames accompanying rhythmic structure of their vocalizations, etc. In such ways, infraphonological descriptions offer the opportunity to more fundamentally characterize the nature of speechlike vocal development.
The role of experience in nonhuman primate vocal development: Evidence from cross-fostered rhesus (Macaca
mulatta) and Japanese macaques (M. fuscata).
Authors: Owren Michael J.
Published: October 2005

Vocal development both in human infants and many songbirds is shaped by a combination of innate predispositions and early auditory environment. In contrast, deprivation experiments with nonhuman primates have suggested that species-typical calls can emerge in the absence of experience with these sounds. To directly test for the possibility of learning effects in primate vocal development, neonatal rhesus and Japanese macaques born to socially housed females were cross-fostered between species. These subjects experienced an altered auditory environment but were treated as ordinary offspring by their adoptive mothers and cagemates. Playback experiments showed that both foster mothers and offspring recognized each other by voice and were appropriately responsive to vocalizations. However, only limited modification of vocal development occurred in the experimental subjects. They generally used calls in a manner matching that of their genetic rather than adoptive species and also produced sound that were not used by their different-species cagemates. [Work supported by NIH.]
The developmental role of spectral relations in perception of the prevocalic [m]–[n] contrast.
Authors: Ohde Ralph N. , Hawkins Anne M.
Published: October 2005

The mechanisms involved in processing spectral change between the nasal murmur and the vocalic transition for speakers of different ages was assessed before and after disruption of the variation in spectra between these properties. Three children, ages 3, 5, and 7, and an adult female and male, produced CV syllables consisting of either /m/ or /n/ followed by /i/ and /u/. In one condition (spectral noncontiguous), the acoustic information surrounding the region of spectral change was digitally removed and in another condition (spectral contiguous) this portion of the signal was retained. In both of these conditions, intervals of silence were inserted between 50-ms segments of murmur and vocalic transition. Across speakers, the results for the spectral contiguous condition support two mechanisms in processing spectral relations, auditory short-term adaptation and auditory memory, but the results for the spectral noncontiguous condition primarily support auditory memory. [Work supported by NIH DC00464.]
The effect of lexical knowledge on children’s phoneme identifications.
Authors: Hurlburt Michael S. , Goodman Judith C.
Published: October 2005

Although adults are sensitive to lexical information when identifying phonemes, little is known about the development of lexical effects. Children appear to process acoustic–phonetic information less efficiently than do adults and to have more global representations of words in their mental lexicons. These differences may lead to larger lexical effects on children’s phoneme identifications. The effect of lexical information on phoneme identifications in 5- and 6-year-old children and adults were examined. Subjects identified the initial phoneme in stimuli from 18 acoustic continua varying in voice onset time. For each continuum, one of the two possible phonemic categorizations formed a word and the other did not. For example, subjects categorized the initial phoneme in a continuum extending from the word desk to the nonword tesk and in a corresponding continuum from the nonword dest to the word test. Children and adults were strongly influenced at the phoneme boundary by lexical status. In addition, children, unlike adults, showed a lexical effect at the endpoints of the continua for /g/–/k/ and /b/–/p/ contrasts, but not for the /d/–/t/ contrast. These results are interpreted in terms of the nature of children’s representations of words in their lexicons and the relationship of those representations to neighborhood density. [Work supported by Biomedical Research Support Grant to the Univ. of California, San Diego.]
Auditory sensitivity in human neonates.
Authors: Shoup-Pecenka Angela G. , Walton Gail E. , Bower Nick , Bower T. G. R.
Published: October 2005

Auditory sensitivity was assessed behaviorally in neonates in the well-baby nursery at a community hospital. Reliability was determined by repeating the measure during the infants’ stay in the nursery. Stimuli used were three frequency bands: 800 Hz and below, 1–3 kHz, and 4–8 kHz. The infants were presented with five different intensity levels: 0, 5, 10, 15, and 20 dB re: normal adult threshold. Assessment was accomplished by an operant sucking paradigm in which the infants controlled stimulus presentation by varying their rate of sucking. If the infants paused longer than a preset interval (1 s) between sucks, the stimulus changed to another level. The first level was absolute 0, in order to get a measure of the infants base sucking rate. The thresholds obtained with this technique more closely approximate those for adults than have previously been reported in this population. Information about speech processing has also been obtained.
Auditory information processing in preschool children.
Authors: Jerger Susan
Published: October 2005

Within the last decade, the study of speech processing has benefited from the application of the methodologies and theories of cognitive psychology. This experimental orientation has particularly illuminated the dependency relations characterizing the processing of speech stimuli. The present study attempts to extend this database by investigating the interactive nature of speech processing in young children. Interactions between the auditory and semantic dimensions of speech were studied with two different types of selective-attention reaction-time (RT) tasks. One methodology utilized conflict and congruence between the auditory and semantic dimensions (a ‘‘Stroop’’ task). The other methodology presented the same speech targets in two conditions−a control condition where the voice dimension varied in isolation as the irrelevant semantic dimension was held constant, and an orthogonal condition where the relevant and irrelevant dimensions varied in an unpredictable manner (a ‘‘Garner’’ task). Results on these two different types of interference tasks provide additional insights into the developmental course of the dependency relations in speech processing. [Work supported by NIH NIDCD.]
Beamforming in the atmosphere near the ground.
Authors: Havelock David I. , Stinson Michael R. , Daigle Gilles A.
Published: October 2005

Adaptive beamforming techniques in the atmosphere have been relatively unexploited. Existing studies that could be applied to the case of atmospheric sound propagation have been mostly restricted to simulations and there is little published data on the actual performance of beamforming arrays in the real atmosphere. The acoustical signals arriving at receiver elements of an array in the atmosphere are influenced by the effects of the ground and ground topography, wind speed and temperature gradients causing refraction, and the loss of wave-front coherence due to atmospheric turbulence. A comprehensive understanding of these effects is required before adaptive beamforming can be properly performed in the atmosphere. This presentation reviews the published work relevant to adaptive beamforming in the atmosphere. Preliminary results obtained with a 16-microphone array in the presence of realistic meteorological and topographical conditions will be discussed. Pure tone frequencies (approximately 100 to 1000 Hz) and other broadband source signals were used, and the propagation studied at various ranges (hundreds of meters). Where possible, the measured results are compared to theoretical predictions. Particular emphasis is given to the effects of wave-front coherence and the associated analysis algorithms and beamforming strategies. Some practical aspects of the implementation and deployment of a beamforming array in the atmosphere will also be discussed.
Computations of measurement system effects in ultrasonic scattering experiments.
Authors: Waag Robert C. , Astheimer Jeffrey P.
Published: October 2005

A recently developed mode, which describes the relation between the spatial localization and the corresponding blur in spatial frequency, has been used to compute the spatial-frequency distribution of measurement system weight on intrinsic parameters of scattering. The computations employ an angular spectrum representation of the emitter beam and detector sensitivity patterns and a narrow-band representation of the emitter waveform and detector time gate. The narrow-band representation of signals permits the effect of the temporal waveforms to be represented as a one-dimensional convolution in wave space. Visualization of the wave space results as translucent reflecting shells show pictorially changes in the distribution of measurement system weight with apodization of the apertures, angle between the emitter and detector, and temporal waveforms. The results illustrate use of the model to design experiments that yield intrinsic scattering parameters and also illustrate transducer array characteristics important in analysis of techniques for the correction of wave-front distortion.
Rate and intensity effects on brainstem binaural interaction component in normal and hearing-impaired subjects.
Authors: Parthasarathy T. K.
Published: October 2005

Rate and intensity were the stimulus parameters utilized to evaluate the binaural interaction component (BIC) of the auditory brainstem response (ABR) in normal hearing and high-frequency sensorineural (cochlear) hearing-loss adult subjects. Rarefaction click-like (2.0 kHz) stimuli of 85 and 100 dB SPL at 11.1 and 44.4/s rate were presented monaurally and binaurally. The binaural interaction component (BIC) was derived by subtracting the summed monaural (SM) waveforms from the binaural waveforms. Both the wave V of ABR and N1–P2 component of BIC consistently evoked shorter latencies with larger amplitudes from all normal hearing subjects than in the cochlear hearing-impaired subjects. Increasing the stimulus rate produced longer latencies and smaller peak amplitudes of the BIC’s and concomitantly longer latencies and smaller wave III and V amplitudes of ABR from both normal and hearing impaired subjects. These results seem to suggest a higher frequency dependence of BIC/ABR.
A hybrid method to simulate acoustic/elastic wave scattering from a rough seafloor.
Authors: Holliger Klaus , Levander Alan R.
Published: October 2005

A hybrid scheme to simulate 2-D wave propagation through a vertically heterogeneous ocean and local scattering from a highly irregular elastic seafloor is presented. The hybrid scheme is based on the combination of Gaussian beam, finite-difference, and Kirchhoff integral solutions of the wave equation. Gaussian beam method, used to propagate the source field through a vertically heterogeneous water column to the scattering region, is regular in the critical and caustic regions, making it ideally suited to accommodate the gradational velocity variations within the oceanic water column, and is numerically efficient. Finite differencing is used to compute the complex acoustic/elastic interaction of this wave field with the rough seafloor. A fourth-order space, second-order time 2-D finite-difference algorithm permits calculation of high-frequency (150–300 Hz) acoustic/elastic scattering from fine-scale (1–10 m) roughness. The backscattered field is extrapolated to a receiver array distant from the scattering locale by means of the Kirchhoff integral, with the Gaussian beams being used in the Kirchhoff kernel.
Directional processing of the simulated broadband reverberation data and its interpretation.
Authors: Kalra Ashok K.
Published: October 2005

Broadband ocean bottom/subbottom reverberation data have been simulated for the Naval Oceanographic and Atmospheric Research Laboratory’s (NOARL’s) Deep Towed Acoustic and Geophysical System’s (DTAGS’s) shooting configuration. The DTAGS is similar to the marine seismic streamer acquisition system, complete with its own omnidirectional marine vibroseis energy source and a set of receiver arrays. It was towed at 300 m from the seafloor in deep waters over a sediment pond to simulate the bottom/subbottom direct path, low grazing angle (±15°) backscattered reverberation data for the Acoustic Reverberation Special Research Program (ARSRP). The DTAGS records the reverberation and/or reflection data from all angles, and the application of the intercept time-slowness (t-p) processing algorithms was studied to filter out the undesired reverberations at high grazing angles. The low grazing angle (±15°) data are then interpreted to identify the (location of) bottom and/or subbottom scattering patches or elements. These are further analyzed to study the reverberation hypotheses. [Work supported by ONR.]
Acoustical measurements in rooms with variable acoustics.
Authors: Jin Shirley , Cervone Richard P. , Chiang Wei-hwa , Siebein Gary W. , Doddington Harold W. , Schwab Wilhelm K.
Published: October 2005

A dedicated, computer-based system was developed to perform a complete set of acoustical measurements of recent interest in full-sized rooms and in scale models of rooms. The measurements included reverberation time, early reverberation time, loudness, early-to-late temporal energy ratios, lateral energy fractions, interaural cross correlation, and speech transmission index, among others. Measurements were made at multiple locations in four large multiuse halls with different variable acoustics features. Measurements were made with and without an orchestral shell in place, with a concert wall in use, with a ceiling lowered to close off the upper part of a balcony, with curtains raised and lowered on the walls of a room, and with a curtain used to close off the rear position of a large room. Changes in the various measurements at equivalent seating locations will be presented. The magnitude of the changes are compared to changes perceived by listeners of various acoustical qualities in a recent study [R. P. Cervone etal., J. Acoust. Soc. Am. 89, 1857 (A) (1991)]. [Work supported by NSF.]