bluuebunny/crossref_metadata_2025 huggingface dataset:
Using electrically evoked auditory potentials in the clinical management of pediatric cochlear implant users.
Authors: Brown Carolyn J.
Published: October 2005

For many young and/or prelingually deaf children, programming the speech processor of the cochlear implant and identifying malfunctioning electrodes or internal device failures can be difficult. Electrophysiologic recording techniques can be used to address both issues. The electrically evoked auditory brain-stem response (EABR) can be used to assist in device programming. Data describing the relationship between EABR threshold and behavioral measures of threshold and maximum comfort level for a group of 26 Nucleus cochlear implant users will be reviewed. Electrophysiologic techniques can also be used to record the stimulus artifact associated with activation of the Nucleus device. This response has been called the average electrode voltage (AEV) and has proven to be useful in identifying cases where there is total failure of the internal components of the Nucleus cochlear implant as well as diagnosing malfunction of individual electrodes. Normative data collected using three different stimulation modes from a group of 20 Nucleus cochlear implant users will be presented., Examples of commonly observed abnormal AEV recordings will be described and compared with AEVs recorded using an internal Nucleus electrode array submerged in a saline tank. [Work supported by NIH and the Iowa Lions Foundation.]
Active matched-field tracking.
Authors: Bucker Homer , Baxley Paul
Published: October 2005

The principal task of a sonar system is to generate possible tracks of an acoustic source. Matched-field tracking [Bucker, J. Acoust. Soc. Am. 96, 3809–3811 (1994)] is a signal processing algorithm for this purpose that has minimum operator input. In this presentation, the method is applied to active sonar systems by extending the definition of covariance matrix elements. A sample simulation will be shown where operator-independent tracks are obtained at different noise levels.
Robust nonadaptive matched-field beamforming in an uncertain ocean environment.
Authors: Harmanci Kerem , Krolik Jeffrey L.
Published: October 2005

Matched-field processing techniques can be both ambiguity-prone and sensitive to errors in the assumed environmental conditions. Although greater robustness to environmental variability can be obtained by the use of data adaptive methods, such as the MV-EPC beamformer [J. L. Krolik, J. Acoust. Soc. Am. 92, 1408–1419 (1992)] or joint estimation of source and channel parameters [D. F. Gingras and P. Gersoft, J. Acoust. Soc. Am. 97, 3589–3598 (1995)], these strategies require higher signal-to-noise ratios. The methods presented here concern the design of robust nonadaptive beamformer weights with sidelobe levels which are less signal-to-noise ratio dependent. As with Chebyshev filters, the weights are designed to minimize the maximum magnitude-squared sidelobe level. Robustness to environmental mismatch is achieved by defining the sidelobe level as the magnitude-squared response averaged over an ensemble of environmental conditions. The two algorithms proposed are a fast iterative constrained minimum variance method and the use of a minimax quadratic programming technique. For an uncertain Mediterranean environment, an improvement in the maximum average sidelobe level of as much as 3 dB over the Bartlett beamformer is achieved. [Work supported by NRaD/ONR.]
The determination of optimum array lengths based on signal coherence in deep and shallow water.
Authors: Carey William M. , Cable Peter
Published: October 2005

Experimental measurements of signal coherence and array signal gain are reviewed for both deep and shallow water sound channels. The signal gain is related to single path or modal coherence lengths through well-known relationships in the statistical theory of antennas. Signal gain measurements in the transverse and longitudinal directions are proffered as the optimum measures of coherence lengths for both broadband and narrow-band signals. Using this technique measurements (<1 kHz) are presented that show for the deep water cases lengths on the order of 300 wavelengths can be achieved while in the downward refraction conditions of a shallow water waveguide lengths between 30 and 100 wavelengths are realized. The measurement of broadband and narrow-band coherence and correlation functions are discussed with emphasis on the role of partly coherent noise backgrounds and multipath interference effects as well as averaging constraints. These results are interpreted with coherence models based on sound scattering from the volume and boundaries of the waveguide. The requirements for the numerical modeling of the signal coherence are presented.
Model-based processing of broadband sources in noisy shallow ocean environments.
Authors: Candy James V. , Sullivan Edmund J.
Published: October 2005

Broadband acoustic sources propagating in a hostile (noisy) ocean complicate the analysis of received acoustic data considerably. Normal-mode models are reasonable propagators for use in a shallow ocean environments. Our previous work developed the Gauss–Markov representation of the narrow-band normal-mode model and then recently extended it to the broadband case [Candy and Sullivan, J. Acoust. Soc. Am. Suppl. 1 98, (1995)]. In this paper the design and trade-offs of the processor are investigated when applied to both synthesized and experimental data in order to construct the desired broadband processor. The enhancement of broadband acoustic pressure-field measurements along with the estimation of underlying model functions using a vertical array is discussed. The model-based approach is developed and implemented for a broadband source using a normal mode propagation model. The structure of the processor is of interest, since it has an implied parallel structure due to the propagation physics, while the optimal estimation solution implies a ‘‘full’’ structure. The apparent discrepancy is resolved and the processor is implemented using a ‘‘bank’’ of narrow-band model-based processors. The resulting broadband pressure-field estimates are quite reasonable for both synthesized and experimental data.
An empirical fractal model for corona discharges in salt water.
Authors: Espinosa J. C. , Jones H. M. , Gleeson A. M. , Rogers R. L.
Published: October 2005

A corona discharge in water and a concomitant acoustic pulse is produced when a high electric field is applied across a pair of electrodes. The corona structure consists of many branching plasma fingers. The acoustic signal is produced by the formation and collapse of a vapor bubble; however, the details of this process are unclear. Furthermore, the relation between the acoustic and fractal stages is unknown. Voltage and current waveforms, obtained previously, are accurately described by a fractal model. High-speed photographs of discharges have been taken to further investigate the nature of corona discharges and elucidate the relationship between the two stages. From these experiments, an empirical model is under development that incorporates both the fractal and acoustic aspects of corona discharges. The most recent results of this effort will be presented. [Work supported by the Office of Naval Research.]
Underwater turbulence injection system for investigation of acoustic propagation in a randomly fluctuating medium.
Authors: Doust Barry J. , Gilbert Kenneth E. , Goodman Ralph R.
Published: October 2005

A preliminary investigation using cold water from melting ice to induce sound-speed fluctuations has shown significant effects on both one-way and two-way propagation. Although the melting ice approach is simple and effective, it is not easily controlled. The purpose of the present research is to develop a method for generating controlled sound-speed fluctuations by creating a thermal field with stable and repeatable statistics. The work has led to a novel cold water injection system for generating thermal fluctuations in an experimental tank. A relatively simple device has been designed for producing a range of turbulence spectra by varying the flow rate and orifice sizes. This paper will focus on the characteristics of the cold water injection system and will discuss its advantages over systems that use, for example, electric heaters or hot water injection to create the thermal fluctuations. Results from preliminary acoustic tests will be discussed. [Work supported by the Office of Naval Research and the Applied Research Laboratory.]
The effect of roadway traffic noise on territory selection by Golden-cheeked Warblers.
Authors: Benson Robert H.
Published: October 2005

Widespread concern that environmental noise produced by humans can negatively affect animal populations is reflected in a growing body of literature. This study evaluates the possible effects of roadway traffic noise on territory selection by the endangered Golden-cheeked Warbler. Seventy-eight listening posts were established randomly in a 212 ha study area in central Texas. Noise exposure at each post was estimated using a noise simulation model based on traffic counts. The presence or absence of warblers at each post was determined by field observations. Data were analyzed to determine if a correlation existed between the estimated noise exposure and the occurrence of warblers at a listening post. Exposure in Leq(h) ranged from 29.7–58.6 dB. Warblers were detected at 30 of the 78 listening posts. When the 78 posts were divided into high-noise and low-noise groups, there was no significant difference between the occurrence of warblers in the groups. Logistic regression failed to reveal a significant correlation between the occurrence of warblers at listening posts and the exposure to noise. It is concluded that, within the range of noise exposures considered in this study, Golden-cheeked Warblers do not select territories based on exposure to roadway traffic noise.
The impact of impulsive noise on bald eagles at Aberdeen Proving Ground, Maryland.
Authors: Russell William A. , Lewis Nelson D. , Brown Bryan T.
Published: October 2005

The U.S. Army Aberdeen Proving Ground supports one of the largest bald eagle concentrations on the Northern Chesapeake Bay (Buehler et al., 1987). The testing of large caliber weapons and detonation of large explosive charges at U.S. Army Aberdeen Proving Ground is creating significant noise and producing concerns on the potential effects on bald eagles. The population using Aberdeen consists of approximately 15 nesting pairs and up to 100 wintering or nonbreeding residents. Systematic observations on potential influence of noise on bald eagles were made from November 1993 through December 1995. We detected no response in a high percentage of nesting and roosting eagles exposed to numerous types of noise at varying levels of intensity.
Response of nonbreeding spotted owls to helicopter and chain saw noise.
Authors: Grubb Teryl G. , Delaney David K. , Reiser M. Hildegard , Beier Paul , Pater Larry L.
Published: October 2005

Mexican spotted owls (Strix occidentalis lucida) were exposed to two types of noisy stimuli: very low altitude helicopter overflights and chain saw activity. The stimuli were presented to the owls at several distances and noise levels during daylight hours in July through September 1995. Responses were characterized into two categories, ‘‘alert’’ and ‘‘flight.’’ ‘‘Alert’’ responses to low altitude helicopter overflights were typical, but ‘‘flight’’ responses occurred for only a small percentage of the trials. Chain saw presentations at similar distances elicited ‘‘flight’’ responses much more frequently. Consideration was given during data analysis to the owls’ hearing range and sensitivity. [Research supported by U.S. Air Force.]
Effects of sound and ultrasound on Zebra Mussels.
Authors: Donskoy Dimitri M. , Ludyanskiy Michael , Wright David A.
Published: October 2005

The freshwater bivalve mollusk, Dreissena polymorpha – better known as the Zebra Mussel, since its introduction into the Great Lakes in 1985 has been quickly spreading throughout the waterways of both the United States and Canada causing serious economic and environmental consequences. The present study has been directed toward developing acoustic techniques to control Zebra Mussel infestation in various water intake and storage facilities. The effects of ultrasonic and hydrodynamic cavitation, low-frequency sound and vibration on various life stage mussels (from eggs and larvae to adults) have been studied. It was found that cavitation can be used as a control measure for Zebra Mussel veligers. The efficiency of the ultrasonic and hydrodynamic cavitation treatments were measured as an output energy rate to achieve 100% mortality. Laboratory experiments demonstrated the effective use of low-frequency waterborne sound to prevent Zebra Mussels from settling and translocating and to reduce reproduction abilities of mussels. [This work has been supported by Grant No. NA26RG0403-01 from the NOAA to the Stevens Institute of Technology, New Jersey Sea Grant College Program.]
Relationship between judgments of neighborhood noisiness and prevalence of annoyance.
Authors: Fidell Sanford A. , Silvati Laura A.
Published: October 2005

Dosage-response functions that relate the time-weighted daily average sound power of outdoor noise to the prevalence of a consequential degree of noise-induced annoyance in communities are often viewed as providing a basis for land use compatibility policy recommendations. Although such functions advance understanding of the rate of growth of annoyance with sound level and of related matters, they do not in themselves dictate any particular policy recommendations. It is therefore useful to consider how the growth of noise-induced annoyance is itself related to other nonacoustic measures of community response to noise exposure, such as the rate of growth of neighborhood noisiness judgments with sound level. A probabilistic model of community response to noise exposure developed by Green and Fidell (1991) is shown to provide a good account of a set of neighborhood noisiness judgments. The model is used to relate the growth functions for judgments of neighborhood noisiness and the prevalence of annoyance to one another.
A study of noise reduction by antisound using bypass in ducts with flow.
Authors: Zhu Zhichi , Guo Rui , Tien Rui
Published: October 2005

Noise reduction in ducts with flow is a very useful project. With common antisound methods, electronic instruments are required, so its application is restricted. By using bypass added to the main duct with flow, downstream noise reduction can also be obtained if suitable bypass parameters are selected: This simple method is completely in accord with antisound principle. But sound field analysis in this case is quite a complicated problem. The numerical and experimental research was completed by the authors. The numerical work included formulating acoustic relations and joint conditions and calculating the transmission loss for various noise sources. The experimental research on a duct with single bypass and outlet absorbing wedge under the conditions of different noise sources and flow velocities was carried out in a national lab. The measured data were in good agreement with the numerical results and considerable noise reduction was obtained in both dB(A) and 1/3 octave band. Finally, a spot test of noise reduction using double bypasses was carried out. It was shown that a noise reduction of 5 dB(A) was obtained even though the situation was not in optimization. [Work supported by NNSF of China.]
Quiet motor design.
Authors: Öztürk Cüneyt , Sönmez Emin , Açikgöz Harun , Göok Birdal
Published: October 2005

Acoustic modeling of appliance motors leads the product designers to fully grasp all the technical features of the motor that cause noise. Utilizing complete analysis packages during prototype development provides the capabilities of existing numerical analysis software to enable the designer to visualize the influence of all mechanical, electromagnetic, and acoustic features on the potential product. The purpose of this study was to develop a methodology to let the designer predict all parameters including mechanical resonances, electromagnetic forces, and aerodynamic and acoustic features that dominate noise spectrum of actual prototypes, during the development stage. This method enables the designer to be aware of all parameters that cause the increase of the audible noise and let them know the facts of using predictive design tools in an efficient and correct way on the basis of developed methodology. The result of this research is a design methodology that leads to the development of low noise products and efficient use of potential design tools.
Temperature variation of elasticity of α-quartz by the rectangular parallelepiped resonance method.
Authors: Ohno Ichiro
Published: October 2005

The resonant ultrasound spectroscopy of a specimen of α-quartz single crystal was carried out up to 558 °C, just below the α–β transition (T0=573 °C), and all of the independent elastic constants were determined simultaneously by the rectangular parallelepiped resonance method. The results show that bulk moduli decrease largely toward T0, while the shear moduli show only slight decreases. The constant, C14, characteristic of trigonal crystals, decreases to just below T0, but it seems not to vanish, but to remain a finite value, even at T0. It is noted that the isotropic aggregate of α-quartz is a curious and scarce material, in the sense that its bulk modulus is smaller than the shear modulus, and Poisson’s ratio is very small or even negative at temperatures higher than 450 °C. The effect of piezoelectricity of α-quartz on the theoretical frequencies was investigated in order to know whether the ordinary nonpiezoelectric theory gives considerably inaccurate resonance frequencies. It was shown that the nonpiezoelectric theory gives a frequency lower than the frequency given by piezoelectric theory, but the difference is 0.5% at most.
Measurements for pressure and temperature dependencies of elastic moduli by the resonant sphere technique, RST.
Authors: Suzuki Isao , Fujio Tomonori , Kikuchi Hiroshi , Oda Hitoshi , Ohno Ichiro
Published: October 2005

The resonant sphere technique, RST, has been developed for measurements of elasticity and anelasticity of small crystal specimens. This method has advantages over other methods, especially in high-temperature and high-pressure measurements. New methods of data acquisition have made it convenient to measure resonance frequency at high temperatures (using a buffer rod), making a 1 K temperature interval measurement possible; this opens up many possibilities in the determination of physical properties of solids. Preliminary measurements of resonance frequency were performed by RST up to 100 MPa, which showed interference of vibration modes between the specimen and the pressure medium, even for helium gas as the pressure medium. This interference may become more serious at higher pressures or under liquid pressure. In order to evaluate such effects, the cavity resonance method was developed by Ohno in 1993, with a spherical shell structure with a spherical specimen at the center. This gives clear boundary conditions in the wave equations. Theoretical evaluation of the resonant frequency on such a system shows the necessity of correction to pressure derivatives of elastic moduli, even in measurements up to 100 MPa.
Simultaneous determination of elastic constants and asphericity of aspherical specimen by the resonant sphere technique.
Authors: Oda Hitoshi
Published: October 2005

The resonant sphere technique (RST) is a method of resonant ultrasound spectroscopy developed to measure elastic constants of solids. In this method, resonant frequencies of a spherical specimen are measured and the elastic constants are determined by comparing the measured frequencies with theoretical ones that have been computed for a set of elastic constants. A perfect sphere is not always obtained, however; the specimen sometimes has small asphericity. In this case, the effect of asphericity on the resonant frequencies has to be corrected. Thus a method has been developed to determine simultaneously the elastic constants and asphericity of an aspherical specimen. When RST is employed for elasticity measurements of an ellipsoidal specimen, the difference between measured and computed resonant frequencies is expressed by δω=φiεi+AijδCij, where summation convention is assumed for repeated indices, and εi and δCij (i,j=x,y,z) are asphericity of the ellipsoid and small corrections for a set of elastic constants, respectively. Since the coefficients φi and Aij are known, the unknown coefficients εi and δCij can be determined by a least-squares method. Actual application will be reported for an ellipsoid of an olivine specimen with orthorhombic crystal symmetry.
Voigt stiffnesses and amplitude-dependent internal friction in
monocrystal silicon.
Authors: Ledbetter Hassel , Kim Sudook , Fortunko Christopher , Heyliger Paul , Tanaka Mitsuru
Published: October 2005

The specimen consisted of a 1-cm-diam monocrystal silicon sphere. Voigt elastic stiffnesses C11, C12, C44 were determined from the macroscopic eigenvibration frequencies. The Cij results agree closely with previous measurements by conventional acoustic methods. The internal frictions Q−1 were determined for two nondegenerate eigenfrequencies. One depends only on the shear modulus C44. The other, composed of 0.64C11+0.32 C12+0.04 C44, is nearly independent of C44. Granato–Lücke plots of ln ε Q−1 vs ln ε−1 showed two regions. The higher strain region showed a slope of approximately 3.5 times that of the lower strain region. A dislocation-model explanation will be offered for higher Q−1 at higher ε.
Transducers and measurements at high temperatures using resonant ultrasound spectroscopy.
Authors: Darling Timothy W. , Migliori Albert
Published: October 2005

Resonant ultrasound spectroscopy (RUS) measurements of material properties at high (above 150 °C) temperatures have been directed mainly at materials of geological interest, but a wide variety of other applications exists for high temperature RUS measurements. These include physical properties (phase transitions, elastic moduli) of novel solid state materials and understanding and control of processing parameters for industrial materials such as ceramics and steels. A RUS measurement system has been developed which operates to 600 °C without buffer rods. A description of the materials used and the transducer construction will be presented with some results from measurements on perovskite-type crystal structures and magnetic materials. A discussion of the limits of the present system and possible techniques for bufferless transducers with operating temperatures to 1000 °C will be presented. [Work supported by the U.S. Department of Energy.]
A review of active and passive basilar membrane cochlear mechanics.
Authors: Allen Jont
Published: October 2005

Since David Kemp first proposed the active model in 1979, the role of the outer hair cell (OHC) in basilar membrane (BM) mechanics has been hotly debated. In the ‘‘active’’ model view, the OHC modulates the motion of the BM traveling wave on a cycle-by-cycle basis, leading to a negative BM resistance and a traveling-wave power gain. Nonlinearity is introduced by assuming that the negative BM resistance depends on the signal level. In the ‘‘passive’’ model view, the OHC controls the stiffness of the basilar membrane, leading to a level-dependent (nonlinear) relative impedance between the BM and tectorial membrane and a nonlinear basilar membrane and transduction response. Both models seem to be able to achieve the important nonlinear variations in responses seen in the BM, OHC, IHC, and neural response, but with differing assumptions and degrees of physical reality. It is now clear that the OHC nonlinearly compresses both the dynamic range of basilar membrane motion (Rhode, 1971; Ruggero, 1990) and the neural response (Yates, 1989), extending the otherwise limited dynamic range of the IHC response. This role of the OHC may be quantified using psychoacoustic masking patterns, two-tone suppression, loudness growth and recruitment, and OAEs as objective measures.
Cochlear nonlinearity: Implications for auditory signal processing and perception.
Authors: Duifhuis Hendrikus
Published: October 2005

Conscious perception of auditory nonlinearity in combination tones, the low-frequency intermodulation products of two or more tones, goes at least back to Tartini (1692–1770). Renewed interest around 1970 [e.g., J. L. Goldstein, J. Acoust. Soc. Am. 41, 676–689 (1967); J. L. Hall, J. Acoust. Soc. Am. 56, 1818–1828 (1974); G. F. Smoorenburg, J. Acoust. Soc. Am. 52, 615–632 (1972)] led to the conclusion that the nonlinearity originates in the (intact) cochlea. At that time, nobody paid special attention to the point that acoustical effects within the cochlea should be reflected at the aural entrance. Today, that issue (DPOAE) is actively explored. The link with auditory perception receives lesser emphasis, hopefully not because a proper psychoacoustic measurement requires more than reading a stimulus parameter (cf. Psychoacoustics and David M. Green). Next, two-tone suppression became an issue where psychological and physiological nonlinear acoustics met. The phenomena are intertwined, and probably inseparable from the point of view of underlying biophysical mechanism. Finally, obviously the auditory nonlinearity is compressive. The negligible impact of this result on development of a biophysical basis for the auditory dynamic range and the decibel scale remains puzzling.
Inner hair cell and organ of Corti responses to very low frequency tones.
Authors: Cheatham M. A. , Dallos P.
Published: October 2005

The timing of excitation observed in the auditory nerve exhibits a strong dependence on best frequency (BF). Fibers innervating the base of the cochlea respond to near threshold, low-frequency inputs approximately in phase with basilar membrane velocity to scala tympani while fibers innervating apical regions respond in phase with basilar membrane velocity to scala vestibuli [M. A. Ruggero and N. C. Rich, J. Neurophysiol. 58, 379–403 (1987)]. Although the latter is consistent with the velocity dependence of inner hair cells (IHC) and with the classical view of hair cell stimulation, the response phase of single units in the base of the cochlea has been difficult to explain. Consequently, IHC recordings from the second turn of the guinea pig cochlea (BF = 4000 Hz) were used to determine phases of depolarization relative to basilar membrane displacement. To better estimate synaptic drive, the organ of Corti response was subtracted from that recorded in the IHC since the voltage gradient that induces transmitter release can be influenced by extracellular responses that reflect receptor currents generated in nearby outer hair cells. Results indicate that IHC depolarization occurs near basilar membrane velocity to scala tympani consistent with single unit excitation in the base of the cochlea. [Work supported by Grant No. 5R01DC00089, National Institute on Deafness and Other Communication Disorders.]
Impact noise exposure in chinchilla: Effects of frequency, level, and interstimulus interval.
Authors: Davis Rickie R. , Murphy William J.
Published: October 2005

The effect of impact noise on hearing threshold was investigated in a parametric study which manipulated frequency, level, and interstimulus interval (ISI). The chinchilla pinna passively amplifies acoustic stimuli between 2 and 6 kHz suggesting greater effects in that frequency range. Exponentially decaying pulses (t = 40 ms) with carrier frequencies of 1, 3, and 8 kHz were presented at peak pressure levels of 114, 117, 120, and 129 dB SPL and ISI of 1, 10, and 100 s. The chinchillas were exposed for 8 h, with one animal per condition. Hearing function was assessed by measuring auditory-evoked potentials from tonebursts at 0.5, 1, 2, 4, and 8 kHz from implanted electrodes. The data indicate a small (<10 dB) permanent threshold shift (PTS) in the 10- and 100-s ISI conditions. For the 1-s ISI conditions, the animals exposed at 129 dB experienced more than 25 dB PTS at high frequencies. Animals exposed at 120 dB exhibited large temporary threshold shifts (TTS) while the animals exposed at lower levels had smaller TTS and minimal PTS. Stimulus level and ISI had significant effects on the PTS while frequency content was not significant.
Neural representation and psychophysical discrimination of vowel formants.
Authors: May Bradford J. , Hienz Robert D.
Published: October 2005

Auditory-nerve fiber responses were modeled to estimate neural representations of frequency changes in the second formant (ΔF2) of the steady-state vowel /eh. Simulations were performed at vowel levels of 33–84 dB, both in quiet and in continuous noise at a constant 3-dB signal-to-noise ratio (S/N). Signal detection analysis of model outputs suggested that formant changes at higher stimulus levels and in background noise were better represented by rate responses of fibers with low spontaneous rates (SR). Psychophysical tests were then performed in cats to measure behavioral thresholds for the detection of formant frequency changes under stimulus conditions similar to those of the neural simulations. Behavioral ΔF2’s were obtained at vowel levels of 10–70 dB, in quiet and in continuous background noise at S/Ns of 3, 13, and 23 dB. ΔF2 decreased with increasing vowel level and increased with decreasing S/N. These trends in psychophysical performance paralleled changes in the quality of vowel representations, particularly those based on discharge rates of low SR auditory-nerve fibers. [Work supported by NIDCD Grant Nos. 5R01DC01388-04 and 2R01DC00109-22.]
The effect on pitch and loudness of major interpulse intervals within modulated current pulse trains in cochlear implantees.
Authors: McKay Colette M. , McDermott Hugh J.
Published: October 2005

Two experiments were completed with five subjects who have been implanted with the Mini System 22 cochlear implant. In the first experiment, 1000-Hz pulse trains were modulated so that there were two high- and eight low-current pulses in each 10-ms period. Five stimuli were constructed with differing time intervals between the two high-current pulses, and a further six stimuli were unmodulated pulse trains with rates between 100 and 250 Hz. All stimuli were loudness balanced and presented to the subjects in a single-interval pitch ranking task. The unmodulated stimuli showed a monotonic increase in pitch with rate. The pitch of the modulated stimuli was mostly determined by the longer of the two intervals between the high currents. When the high currents were very close, the modulation period was also important in determining the pitch. The second experiment used constant-current pulse trains with two pulses in every 20 ms. The effect on loudness of the interval between the two pulses was measured using loudness balancing. For interpulse intervals less than 4 ms the loudness increased as the interval decreased. This result implies that a facilitatory effect dominates over any refractory effect on loudness at short interpulse intervals.
Effects of meclizine in young adults, measured with otoacoustic emissions, REPs/ABR, qEEG, and a computerized test of eye–hand coordination.
Authors: Lauter Judith L. , Wood Suzanne B. , Lynch Onita , Agnew Kaye
Published: October 2005

Twelve neurologically normal young adults were tested before and after administration of meclizine, an over-the-counter medication for motion sickness. The battery consisted of four components: (1) repeated-measures distortion-product otoacoustic emissions (DPOAEs); (2) the repeated-evoked-potentials version of the auditory brain-stem response (REPs/ABR); (3) quantitative electroencephalography (qEEG) measured over left- and right-side auditory cortex; and (4) a computer-based eye–hand coordination task. The battery required approximately 1.5 h to complete. Each subject was tested with the battery in each of eight longitudinal sessions: three times on a control day (no medication); the same times on a second day one week later (medication at mid-day); and 24- and 48-h check-up sessions following the medication day. Results show dramatic changes in all battery components, with details suggesting the site(s) of action of this type of antihistamine. The ‘‘auditory-system cross sections’’ yielded by this battery make it possible to observe effects from periphery to cortex, including evidence linking otoacoustic emissions with central auditory physiology. Implications range from cautions regarding the acute effects of antihistamines, to physiological support for using such medications to improve performance in learning-disabled children.
Joint effects in the mid-frequency vibration of connected plates.
Authors: Igusa T.
Published: October 2005

Structure-borne noise in coupled systems has been shown to be highly sensitive to joint properties. In this presentation, the effects of joint behavior is examined for coupled plates joined in the canonical L-shaped configuration. The effects of the variation of the joint properties with respect to the coordinate axis along the two-plate junction is of interest. Mid-frequency loads are used, where the modal density is not sufficiently high for standard statistical energy analysis. The problem is analyzed using several methods. A mobility approach [J. M. Cuschieri, J. Acoust. Soc. Am. 87, 1159–1165 (1990)] is used as a benchmark, which, for the thin-plate model, is exact except for mode truncation. The problem is then examined in the perspective of the following two approximate methods: a spatial and temporal averaging method using energy and intensity as the primary field variables [O. M. Bouthier and R. J. Bernhard, AIAA J. 30, 616–623 (1992)] and an asymptotic method, based on Skudrzyk’s Mean Value Theory [T. Igusa and Y. Tang, AIAA J. 30, 2520–2525 (1992)]. It is found that the effects of the variations in the joint properties can be interpreted using wave vector decompositions.
The vibro-acoustic response of coupled structures using hybrid analytic-numeric methods.
Authors: Grosh Karl , Halliday Peter J.
Published: October 2005

A hybrid analytic-numeric formulation for the time harmonic structural acoustics problem is presented. The variational framework for the seamless inclusion of analytic solutions into the Galerkin finite element formulation for a fluid-loaded structure and results of the application of this method are given. One goal of this formulation is to increase overall efficiency by eliminating regions of the structure from the computational domain via an analytic representation of the response. In this way, the total degrees of freedom present in the problem will be reduced. This reduction in the degrees of freedom enables higher frequency, more complex problems to be solved by decreasing memory requirements and compute time. The analysis of complex structures, comprised of structural members coupled at joints, is facilitated by this approach. Using a discretization of the equations of elasticity for the joint, its response may be represented to a desired level of accuracy. The elasticity representation is coupled to the reduced plate or shell theory producing an efficient model of the complete structure. The effect of the joint and the level of modeling detail required for the desired fidelity of prediction for the vibration and acoustic response of the system are studied.
Multiple-reference adaptive active noise control in enclosures.
Authors: Rhea Zane M. , Sommerfeldt Scott D. , Burroughs Courtney B.
Published: October 2005

Noise control of multiple noise sources in 3-D enclosures remains a concern in many applications. This is of particular interest in vehicles, where multiple primary sources contribute to the sound field inside the enclosure. When utilizing active noise control (ANC) systems in these applications, multiple reference inputs are required. A comparison of active noise control with multiple and single reference inputs of multiple noise sources is presented in a case format. Since most sources are structural in origin, independent harmonic vibration of two of the rectangular enclosure walls are used as the primary noise sources. Although a multiple reference input ANC system is much more successful at controlling multiple noise sources, care must be taken in choosing the reference inputs. If the reference inputs are not independent the ANC becomes ineffective. Also, a case study of sound-pressure reductions obtained for on and off resonance of both the enclosure and the enclosure walls is presented. [Work supported by the Applied Research Laboratory.]
Voice effects in implicit memory tasks.
Authors: Brown Julie M. , Fowler Carol A. , Rueckl Jay G.
Published: October 2005

Spoken words are easier to identify if they have been heard recently. This phenomenon, known as repetition priming, can be used to investigate the processes underlying word recognition. Using an implicit memory paradigm, this study looked at the effect of changing the voice of the speaker on repetition priming. Voice effects occur if repetition priming is reduced when a spoken word has been heard in different voices at study and test. Voice effects have been found in implicit memory tasks, such as word identification and word-stem completion [B. A. Church and D. L. Schacter, JEP:LMC 20, 521–533 (1994); S. D. Goldinger, doctoral dissertation, 1992]. This study investigated if these results could be generalized to other implicit memory tasks—specifically, lexical decision, naming, and a new task, auditory fragment completion. No voice effects were found with any of these three tasks. These results are problematic for current accounts of word recognition and imply that as yet unidentified factors control the occurrence of voice effects.
Toward a simple resolution of the temporal resolution/integration paradox.
Authors: Formby C. , Forrest T. G. , Heinz M. G. , Hargus S. E. , Zeiders J. W.
Published: October 2005

Green [Time Resolution in Auditory Systems, 1985] distinguished between two broad classes of paradigms that presumably represent the two ends of the auditory temporal processing continuum. At one extreme are measures of temporal integration (TI) that estimate the maximum time over which acoustic information can be stored. At the other extreme are measures of temporal acuity/resolution (TA) that estimate the briefest detectable change in acoustic information. The goal of both paradigms is to estimate a time constant (τ) for the auditory system. Traditionally, τ1 reported for TI is more than an order of magnitude longer than τA estimated for TA. The aim of this study was to resolve this apparent paradox. Detection thresholds were obtained for a range of brief bandlimited (WN=62–6000 Hz) increments within a broadband noise to estimate τ in TI and TA tasks from the same listeners. For each WN condition, detection thresholds were measured as a function of (1) increment duration (PN=10–480 ms) by tracking increment level adaptively to estimate τI and (2) increment level by tracking increment duration adaptively to estimate τA. The resulting τI and τA estimates are comparable and vary inversely with WN from about 70 to 7 ms. [Research supported by NIH.]
Fast-acting compression in human hearing.
Authors: Carlyon Robert P. , Datta A. Jaysurya
Published: October 2005

Physiologically motivated auditory models calculate excitation from a compressed and rectified version of auditory filter responses. Unlike the ‘‘power spectrum’’ model, they predict that, when the responses of a filter to two sounds have equal power but different peak factors, the sound producing the less peaked response will produce more excitation. This was confirmed by experiments using two sounds, each consisting of harmonics 2–20 of a 100-Hz fundamental, presented at 68 dB SPL/harmonic, and with the harmonics summed in either positive or negative Schroeder phase. Kohlrausch and Sander [J. Acoust. Soc. Am. 97, 1817–1829 (1995)] have shown that the response of an auditory filter centered on 1100 Hz to the positive phase complex is highly modulated, whereas that to the negative phase complex is not. It is reported that the threshold for a 10-ms 1100-Hz signal presented 5 ms after the positive phase stimulus is approximately 10 dB less than after the negative phase stimulus. Also, listeners judged harmonics 9–13 of the positive phase sound to be quieter than the corresponding harmonics of the negative phase sound. It is concluded that the results reflect fast-acting compression in the human auditory system.
Angular dependence of Bloch wavepackets.
Authors: Gaumond Charles F. , Drumheller David
Published: October 2005

The contribution to an echo by a particular scattering mechanism, which occupies a specific region in the time-frequency or time-scale domains, is defined as a wavepacket [N. Yen, J. Acoust. Soc. Am. 81, 1841–1850 (1987)]. Previous studies have isolated wavepackets generated by specular reflection, Bragg reflection and Bloch waves in backscattered echoes from a ribbed, finite cylinder at a few discrete target aspect angles. For this target, the echoes mainly contain components from specular reflection and Bloch waves in the frequency region near ka≂5. These two kinds of wavepackets are experimentally extracted in the time-scale domain over the angular range from 10° to 70°. The time extents and spectra of these wavepackets are shown to vary with target aspect angle. This angular dependence is shown to be related to physical mechanisms. [Work supported by NRL 6.2 funds.]
Acoustic scattering by a fluid-loaded cylindrical shell with an internal plate.
Authors: Klauson Aleksander , Metsaveer Jaan , Baillard André , Decultot Dominique , Maze Gérard
Published: October 2005

An experimental and theoretical study of acoustic scattering from a fluid-loaded circular cylindrical shell with an axially attached internal plate is presented. The normally insonified stainless-steel shell has an outer to inner radius ratio b/a=0.98. A stainless-steel plate of the same thickness is diametrically soldered, inside the shell, at both edges along the axis. The object is closed by two flat circular endcaps and is vertically immersed in a water tank (6 m×4 m×3 m). The aim of the study is to separate the effects of the shell and those of the plate and to interpret different sound generation mechanisms of the structure. The numerical simulation is done by the modal expansion method using the unstiffened cylindrical shell eigenmodes. The shell is taken as infinitely long. The internal plate is considered as a line constraint with the frequency-dependent impedance. The comparison between theoretical and experimental results is achieved by an analysis of backscattered spectra and of arrival times of backscattered echoes. The scattering from the structural joints, the generation and transmission of flexural waves through the internal plate, and the interaction between different vibration forms are observed and analyzed. [Work supported by NATO.]
Strong bending modes for scattering from elastic spheroidal solids and shells.
Authors: Werby Michael F. , Sidorovskaia Nataly A.
Published: October 2005

Bending (flexing) modes are excited when signals scatter at oblique incidence from spheroidal shells [M. Werby et al., J. Acoust. Soc. Am. 85, 2365 (1989)]. This was inferred by comparing the exact T-matrix resonance calculations with those predicted from Timoshenko beam theory. A more sophisticated approach was also developed using the general phase- integral method that allowed for nonuniform shapes. The possibility of the existence of such modes not only for fairly thick shells but also for thin shells is considered. Acoustical signals scattered by elastic shells of various materials, aspect ratios and shell thickness are investigated. The presence of bending modes even for very thin shells is demonstrated. It is showed that for thick shells the resonances manifest themselves as maximum amplitude returns while for thin shells they manifest themselves as minimum amplitude returns. The effect is associated with the transitional nature of a rigid-like background to a soft-like background for the two extremes so that the return signals vary in their coherence from adding constructively to adding destructively over the thickness variation. The sensitivity of resonance locations as a function of the elastic parameters is also presented. [Work supported by Naval Research Laboratory and Office of Naval Research.]
Theory of the scattering of an acoustical signal from an elastic spheroidal shell near reflecting or absorbing interfaces.
Authors: Sidorovskaia Nataly A. , Werby Michael F.
Published: October 2005

A new formulation that allows one to describe backscattered echoes from elastic shells near pressure release, rigid, and absorbing planer interfaces is presented. The proposed formulation is always consistent—in contrast to earlier formulations—even at low frequencies and large distances from the interface. It allows for the rapid reproduction of backscattered echoes over frequency ranges of practical interest. This novel approach is developed and is shown to be sufficiently general to allow for nonreflecting smooth surfaces. The method has been implemented and numerical results for both pulse and continuous wave signals scattering from various shells are carried out. The studies for various object materials, distances from the interface, and for the effect that the three type of interfaces have on the detected signals are presented. [Work supported by Naval Research Laboratory and Office of Naval Research.]
Diffraction from simple shapes by a hybrid asymptotic-numerical method.
Authors: Montgomery Joshua M. , Barbone Paul E.
Published: October 2005

The application of a hybrid asymptotic/finite-element method to the problem of scattering from prismatically shaped objects is considered. The hybrid method is based on patching a short wavelength asymptotic expansion of the scattered field to a finite-element interpolation of the near field. In patching, the diffracted field shape functions with unknown amplitude are forced to agree smoothly with the solution in the near field along a curve at a prescribed distance from the diffraction points. An asymptotic DtN (Dirichlet-to-Neumann) map on this artificial boundary represents the effect of the outer domain on the solution within this new boundary. This allows us to replace the original boundary value problem with an asymptotically equivalent boundary value problem, the domain of which is small and efficiently discretized. The method is applied to diffraction by a blunted wedge, which in this context represents a degenerate prism. The hybrid scattering solution shall be compared to a complete analytic field representation found using matched asymptotic expansions. [Work supported by ONR.]
Backscattering of obliquely incident plane waves by a composite cylindrical shell constructed of isotropic and transversely isotropic layers.
Authors: Kaduchak Gregory , Loeffler Charles M.
Published: October 2005

Acoustic scattering from a transversely isotropic cylindrical shell excited by an obliquely incident plane wave is examined. The shell is comprised of N layers which may be described by isotropic or transversely isotropic material parameters. The present research solves the boundary value problem for a transversely isotropic, infinite cylindrical layer within the framework of exact 3-D elasticity theory. The layers which comprise the shell are connected via a ‘‘propagator matrix’’ which relates the interior and exterior boundary conditions. The backscattering form function is then constructed for several commonly used composite materials which display transverse isotropy. The results for anisotropic shells are compared to results found for isotropic shells with similar parameters. Here, attention will be given to the similarities (and dissimilarities) of the scattering mechanisms which are the chief contributors to the backscattering form function as the degree of transverse anisotropy is increased. Analysis of the scattered waveform through Fourier synthesis into the time domain will also be discussed. [Work supported by ONR.]