bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-frequency scattering from the upper crust
Authors: Diachok Orest , Shaffer John , Henderson Laurel
Published: October 2005

The rms roughness of sediment-free basalt at a site east of the East Pacific Rise [measured by Lonsdale et al. (1980)] was computed versus averaging length for predictions of scattering loss versus Fresnel zone dimensions. The source-receiver geometry replicated previously, reported measurements of the reflection coefficient versus grazing angle at a nearby, sediment-free site [Diachok et al. (1986)]. The computed roughness increased slowly with decreasing grazing angle (θ) at large θ, being about 8 m (at 20 Hz) at 60°, and increased rapidly with decreasing grazing angle for small θ, being about 38 m (at 20 Hz) at 10° along a track that paralleled the ridge axis. The effective rms roughness inferred from the reflectivity data for 50° < θ < 70° was 6 m (at 20 Hz along a parallel track), approximately consistent with the inference from the deep tow bathymetric data. At large θ, the effective roughness r is much smaller than the wavelength λ, permitting use of Eckart scattering theory. At small θ, however, r and λ are comparable, violating the Kirchhoff approximation. Implications of these observations and other calculations for modeling reflectivity from sediment-free/thinly sedimented basalt, a prevalent feature of the Pacific, will be discussed.
Selected examples of Scholte wave propagation in deep and shallow water
Authors: Fisher Craig A. , Ali Hassan B.
Published: October 2005

The Naval Ocean Research and Development Activity recently completed a series of three experiments to measure very low-frequency (VLF) seismo-acoustic propagation in both shallow and deep water marine environments. A vertical hydrophone array and ocean bottom instruments were deployed in all three experiments. The ocean bottom instruments contained both hydrophone and three-component geophone sensors. In the single shallow water experiment, measurements were also made with buried three-component geophones. We compare the VLF propagation characteristics in deep and shallow water seen with ocean bottom and water column sensors. The importance of Scholte wave propagation in accounting for both signal and ambient noise energy at near bottom receivers is shown for selected frequencies using both measured and modeled results. Necessary environmental conditions for Scholte wave excitation are also examined.
Gaussian beam method for underwater acoustic reflection from an elastic bottom
Authors: Lu I. T. , Gao X. J. , Felsen L. B.
Published: October 2005

The Gaussian beam method furnishes a potentially useful numerical algorithm for modeling propagation in an inhomogeneous ocean environment. However, the paraxially approximated beams in the heuristically discretized stack suffer from spectral deficiencies that are problem dependent and make a priori predictability uncertain. Understanding these deficiencies may provide clues as to how to deal with them. The present test environment is a line source excited homogeneous ocean with a solid bottom that gives rise to two distinct critical reflections associated with the compressional (P) and vertical (SV) waves, respectively. Stacks of narrow beams, which have localizing advantages, have previously been found incapable of accounting for the critical angle (head wave) effects when the relevant wave phenomena involve only P or SV (horizontal shear), respectively [I.T. Lu, L. B. Felsen, and Y. Z. Ruan, Geophys. J. R. Astron. Soc. 89, 915–932 (1987)]. It is confirmed here that this situation persists in the presence of P-SV coupling. As before, very wide paraxial beams or narrow beams with full spectra remove these effects, but tracking the latter is computationally more difficult, while tracking the former is inconvenient and uncertain for successive encounters with an environment. Various alternative options are examined to cope with these difficulties. [Work supported by NOSC.]
Response of coupled one-dimensional dynamic systems
Authors: Dickey J. , Maga L. J. , Maidanik G.
Published: October 2005

Attention is focused on a complex of one-dimensional dynamic systems. The extent of a dynamic system is defined in terms of two terminal positions, one at each of two junctions. A terminal vector per junction can thus be constructed. The propagation in a dynamic system is defined in terms of two propagation functions each describing the propagation toward one or the other junction. A diagonal propagation matrix per junction can thus be constructed. The coupling among the dynamic systems is defined in terms of two junction matrices. The external drive at a position on a given dynamic system is defined in terms of the responses that it initiates toward one junction and toward the other junction. With this model and definitions of a complex of coupled one-dimensional dynamic systems one may appropriately derive the various component matrices of the impulse response matrix. The matrix yields the response of the complex to the appropriately defined external drive vector. The derivation is explained and discussed. The basic (exponential-type) propagation forms and the nonbasic (e.g., Bessel functional-type) propagation forms are contrasted. The utility of the formalism is briefly cited and discussed.
Coupled systems of anisotropic layers: A group formulation
Authors: Schoenberg Michael , Muir Francis
Published: October 2005

A matrix formalism allows for the simple calculation of the anisotropic, homogeneous medium equivalent to a stationary distribution of thin layers in welded contact. Each layer itself may be an elastic anisotropic medium. The calculated medium is equivalent to the layered medium in the long wavelength limit. The physical properties of any constituent of the heterogeneous system can be shown to be transformable to an element of a commutative group. Adding group elements GA and GB (corresponding to thin layers of constituents A and B, respectively) gives the group element for the homogeneous medium equivalent to the interleaved layers of A and B. The group formulation, which is essentially a statement of conservation laws applicable to layered media, enables us to “decompose” an anisotropic medium into several constituent sets of layers by successive additions of inverse elements, i.e., subtractions. If, after each subtraction, the remaining group element corresponds to a stable anisotropic medium, a valid decomposition is obtained. Within the group of all anisotropic constituents there are nests of subgroups, each subgroup corresponding to a symmetry system more restrictive than the most general triclinic anisotropy. Given the symmetry systems to which the constituents belong, the subgroup structure reveals, a priori, the symmetry of the equivalent medium.
Bottom classification using backscattering at vertical incidence
Authors: Jackson Darrell R. , Nesbitt Eric
Published: October 2005

A technique has been developed for measurement of bottom geoacoustic properties using backscattering at vertical incidence. The parameters of a scattering model are determined by a maximum-likelihood fit to received intensity as a function of time. The procedure provides measurements or bounds for the following sediment bulk acoustic properties; impedance, absorption coefficient, and volume scattering strength. In addition, a measure of interface roughness can be obtained if the coherent component of recieved intensity is negligible. The method has been tested using high-frequency data from shallow silty and clayey sites. [Work supported by ONT and NORDA.]
Time spread of bottom interacting signals from an abyssal plain environment
Authors: Vidmar Paul J.
Published: October 2005

Measured signals from explosive sources are examined to determine some characteristics of the time spread introduced by bottom interaction in an abyssal plain area. Broadband (10–1600 Hz) acoustic data are examined that sample the transition from sediment penetrating paths that refract within the sediment to those that reflect from the basalt substrate beneath the sediment. Different characteristic time spreads at high and low frequencies were observed. In a high-frequency band (1500–1600 Hz), the time spread is relatively short (∼200 ms), while in a low-frequency band (50–150 Hz) the time spread is very long (>0.5 s). The short duration of the high-frequency time spread is consistent with reflection from layer interfaces in the sediment. The long duration of the time spread at low frequencies is consistent with interaction with the substrate (e.g., scattering). [Work supported by the NORDA Bottom Interaction Project and the ONR AEAS Program.]
Development of polyurethane encapsulants with improved resistance to seawater exposure
Authors: Stack G. M. , Miller J. M. , Chang E. Y.
Published: October 2005

Polyurethanes have been widely used as underwater acoustic encapsulants for over 20 years. In an attempt to produce polyurethane encapsulants with improved resistance to seawater exposure, polyurethane systems containing aliphatic isocyanate groups were investigated. Several commercial prepolymers containing aliphatic isocyanate groups were obtained for evaluation. Initially, low-temperature cure systems were developed to cure these prepolymers. It was found that the physical and acoustic properties of the resultant polyurethanes depended significantly on the composition of the cure formulation. The effect of prepolymer composition on the properties of the cured urethanes was then investigated. In particular, the molecular weight and isocyanate content of the prepolymers were varied. Several urethane systems suitable as underwater encapsulants were developed. These urethanes were subjected to long-term aging in seawater. It was found that this exposure to seawater did not significantly affect the dynamic mechanical properties of these polyurethanes. [Work supported by Sonar Transducer Reliability Improvement Program (STRIP).]
Cross-series selective adaptation with vowels
Authors: Dutton Dawn L. , Sawusch James R.
Published: October 2005

Cross-series selective adaptation has been found for vowels [J.J. Godfrey, Percept. Psychophys. 28, 103–111 (1980)], but the stimulus attributes relevant to adaptation were not clearly inferable. The predictions of two models of vowel recognition, the relational model and the octave band model [D. L. Dutton, J. R. Sawusch, and K. C. Tsoi, J. Acoust. Soc. Am. Suppl. 1 81, S18 (1987)] were tested using selective adaptation. An EHAE series served as the base continuum. Five vowels were generated to serve as adaptors. The relationship between the test series and the adaptors could be represented in three ways, depending on the stimulus information assumed to be relevant for pattern recognition. The two models above employ different frequency-based representations. A third model assumes adaptation is based on the pattern of movement of spectral peaks over time. Adaptors were constructed to be similar to one endpoint of the test series based on each of these three representations. Results will be discussed in terms of what cross-series adaptation can tell us about the representations that may be used during vowel recognition. [Work supported by NINCDS.]
Effects of nonstationary characteristics on vowel perception
Authors: Carré René
Published: October 2005

Amplitude transition effects were studied by means of a formant synthesizer. The signal amplitude control is located either between the vocal source and the formant filters or between the formant filters and the output. In the first configuration, corresponding to the human vocal tract situation, at the beginning of the amplitude transition, an impulse response of the formant filters is obtained. In the second configuration, the formant filters are always in a stationary state and, hence, the spectrum structure of the formant filter outputs is harmonic. The distortions introduced by the amplitude transitions do not induce more information on the transfer function of the formant filters. Clear spectral differences were obtained when comparing the two synthetic signals, at their onsets. Information on formant frequency can be obtained in the case of the first configuration even if F0 is high. It has been shown that signal differences obtained by the two configurations are specifically processed by the human auditory system and induce displacements of [i]-[e] boundaries. Moreover, the vowel spectra corresponding to the boundaries do not have a harmonic component in the center of the first formant.
The role of rate of transition in the perception of place of articulation
Authors: Zakia Renee A. E. , Kingston John
Published: October 2005

Kewley-Port et al. [“Perception of static and dynamic acoustic cues to place of articulation in initial stop consonants,” J. Acoust. Soc. Am. 73, 1779–1783 (1983)] showed that listeners can reliably identify the place of articulation of initial bilabial and alveolar stops in stop-vowel syllables with severely truncated vowels from just the first 20 ms of the syllable, which includes the burst and the beginning of the formant transitions. However, they showed that listeners must hear substantially more of the formant transitions, 40 ms or more, to identify the stop's place of articulation when the stop is velar. They speculate that their listeners' need for a longer transition may reflect a slower change in formant frequencies observed overall for velars compared to stops at other places of articulation. Slower formant frequency changes for velars probably arise from the greater inertia of the tongue body compared to the tongue tip or lip, as do the longer voice-onset-times (VOTs) observed for velars versus bilabials or alveolars. If a listener has other (spectral) cues that a stop is a velar, then he will accept stimuli with longer VOTs as voiced than if the other cues indicate another place of articulation. Though the longer VOTs are not themselves cues that the stop is a velar, they may enhance that percept [cf. K. Stevens et al. “Toward a phonetic and phonological theory of redundant features,” in Invariance and Variability in Speech Processes, edited by J. Perkell and D. Klatt (Erlbaum, Hillsdale, NJ, 1986), pp. 426–449]. Again assuming that other cues to place are present, slower transitions may enhance the identification of a stop as velar in a similar way, but could have either a negligible or deleterious effect on identifying a stop as bilabial or alveolar. In this study, ABX-format discrimination experiments are being conducted in which listeners hear short (100 ms) CV syllables in which the second and third formant transitions match natural values for the syllables [ba, da, ga, bi, di, gi] in direction and magnitude, while their rate of change is varied in 15-ms steps across a range of 15–90 ms. The stop bursts have been excised from these stimuli so the only cues to place are in the formant transitions. It is expected that listeners' ability to discriminate place of articulation to degrade in two directions, with artificially short transitions for velars and artificially long transitions for nonvelars.
An evaluation of psychophysical trading relations and perceptual cues
Authors: Pastore Richard E. , Layer Jody Kaplan
Published: October 2005

Trading relations have been the empirical and theoretical focus of a number of research studies over the last decade. This paper provides a careful examination of the concept of a cue, the concept of a trading relation between cues for a given perceptual contrast, and published claims for empirical demonstrations of trading relations. While true trading relations should be expected for most types of perceptual phenomena, it was discovered that many studies claiming to find a trading relation have only demonstrated the effects of a single cue. Furthermore, some aspects of trading relations may be based upon a failure to adequately consider critical underlying assumptions about the nature of the continuum along which the dependent variable is defined. The theoretical implications of trading relations will be discussed. [Research supported in part by a NSF grant to the first author.]
Integrality and trading relations across syllabic and lexical boundaries
Authors: Torniak Gail R. , Sawusch James R.
Published: October 2005

Previous research using a speeded classification task with noise-tone analogs of monosyllables and disyllables has shown that monosyllabic stimuli show integral processing of adjacent phones when perceived as speech, but separable processing of adjacent pitch and amplitude information when heard as nonspeech. Furthermore, this integrality effect was found to be more pronounced within syllables than across syllable boundaries. It was suggested that this pattern of results reflects a speech mode of processing. The purpose of the present experiment was to determine whether trading relations can also be attributed to language specific coding processes or, to the auditory integration of information spanning syllable (and lexical) boundaries. Analogs of speech stimuli known to produce a trading relation [Repp et al., J. Exp. Psychol.: Hum. Percept. Perform. 4, 621–637 (1978)] were constructed and tested in a speeded classification task. The results, and implications of these findings, will be discussed. [Work supported by NINCDS.]
Temporal and spatial correlations for low-freqeuncy ambient noise in a diffuse ice edge
Authors: Makris N. C.
Published: October 2005

Low-frequency ambient noise data acquired during Mizex 84 have been analyzed for temporal and spatial variations. Several concurrent time series of rms pressure in the 25- to 50-Hz band sampled at 30-s intervals and of a few hours in duration were constructed from hydrophone data taken at various separations within a 10-km range. During noise episodes, a time scale on the order of 10 min has been obtained via autocorrelations. Also, variations in noise level of up to 7 dB between sensors as close as 1/2 km, together with crosscorrelations which are high at separations of 5 km but significantly smaller at half that distance, suggest a spatially banded or striated noise generation process. [Work supported by the Office of Naval Research.]
Statistical characterization of Arctic under-ice acoustic bursts and tonals
Authors: Nagle Samuel M. , Siedenburg Clinton T. , Ritcey James A.
Published: October 2005

A 10-min time series of FRAM II Arctic under-ice noise data is analyzed, extending the results of an earlier study [J. G. Veitch, A. R. Wilks, and S.C. Schwartz, “Characterization of Arctic undersea noise,” pp. 45, Dep. Stat., Princeton University (June 1983), AD-A130 397/3 (No. 22, 1983)]. Specific analysis is conducted on the impulsive noise bursts and tonals that are characteristic of underwater noise when an ice cover is present. Point process modeling of the times of arrival of the impulse bursts is performed by testing the empirical distribution of the burst event interarrival times against an exponential parent distribution, characteristic of a Poisson process. Goodness-of-fit tests are invoked, as well as a test for serial correlation. Results suggest that the burst event point process may be modeled as a piecewise constant nonhomogeneous Poisson process. This model is accepted at > 5% confidence for all tests applied. Though a limited data set is utilized, the analysis methodology developed is applicable to larger sets of data. Spectral content of tonal components are also examined using Thompson's multiple window technique, and a harmonic relationship is found to exist.
Extracorporeal shock wave lithotripsy of gallstones: Objectives, current limitations, and preliminary in vitro and in vivo observations
Authors: Thistle J. L. , Petersen B. T.
Published: October 2005

Surgical removal of gallstones is performed about 500 000 times per year in the United States. Although the usual cost ranges from $5000 to more than $10 000 per patient, the operative mortality is less than 1% for otherwise healthy persons. Nonsurgical dissolution of gallstones is often possible, but many gallstones contain calcium compounds that slow or prevent dissolution using the direct content cholesterol solvent, methyl tertbutyl ether (MTBE). Extracorporeal shock wave lithotripsy (ESL) has potential clinical utility for facilitating dissolution and possibly allowing spontaneous or induced passage of small fragments via the bile ducts and intestines. Obstacles to be overcome include predictable fragmentation of multiple stones up to 3 cm in diameter so that all particles are small enough to be rapidly dissolved or pass safely through the bile ducts (⩽ 3 mm). This must be achieved using biologically tolerable shock wave dosages without requiring general anesthesia within one or two treatment sessions. Acute and chronic safety, patient acceptance, and cost must be competitive with surgical treatment. Initial experience suggests that only solitary noncalcified stones (10% of patients with stones) have a high probability of success using ESL plus oral bile acid dissolution therapy. Improving ESL technology and direct contact fragment dissolution using MTBE should increase the clinical utility of shock wave lithotripsy of gallstones.
Cavitation in flowing media by lithotripter shock waves in vitro and in vivo
Authors: Miller Douglas L. , Delius M. , Williams A. R. , Schwarze W.
Published: October 2005

Cavitation produced by lithotripter shock waves was characterized in vitro in water and blood, and in vivo in aortic blood by means of a resonant bubble detector. The 1.6-MHz detector can detect and count 4 ± 1-μm-diam bubbles flowing through it by receiving their second harmonic emissions at 3.2 MHz. Spark-gap lithotripters were used to expose the flowing liquid upstream of the detector at the shock wave focus. This system was readily able to detect bubbles resulting from shock wave-induced cavitation in both water and blood flowing through plastic tubes in vitro, and even in blood pumped by the heart through a plastic arteriovenous shunt. Multiple (up to several hundred) bubble counts were obtained for each shock wave. However, for 200–400 shock wave exposures of each of two dogs, this system was unable to detect evidence of shock wave-induced cavitational activity occurring within the intact vascular system in vivo. [Work supported by Dornier Medizintechnik and by NIH Grant CA 42947.]
Determination of design parameters for an ultrasonic kidney stone disintegrator
Authors: Agarwal R. , Singh V. R.
Published: October 2005

Acoustic techniques are now increasingly used for the removal of kidney stones without surgery. In the past, generally, acoustic shock wave techniques and lithotripsy have been used. However, focused ultrasound may be used to disintegrate such stones, without any effect on the surrounding tissues. Ultrasonic characteristics of kidney stones are studied to determine further the design parameters such as modulus of elasticity, acoustic impedance, frequency of vibrations, etc., to develop a kidney stone disintegrator. The value of ultrasonic velocity in kidney stone in vitro is found to be almost double that of water or soft biological tissues.
Effect of foundation design and resilient mount positions on structure-borne noise transmission
Authors: Kasper Peter K. , Miller Russel D.
Published: October 2005

A typical structure-borne noise control configuration consists of a vibrating machine, a set of resilient isolation mounts, a foundation supporting structure, and a building floor or deck. If the floor is represented by an infinite flat plate and the foundation is comprised of structural beam elements, the acoustic power transmitted to the floor can be calculated in exact fashion using the dynamic direct stiffness technique. This analysis approach involves the representation of beam segment properties in terms of dynamic frequency-dependent stiffness coefficients. The solution of dynamic displacement response to a harmonic input force parallels the solution of static deflections to an applied constant load. Calculations of transmitted acoustic power were made for a range of foundation structural parameters and resilient mounting configurations. The results indicate the sensitivity to such design parameters on structure-borne noise transmission.
Reflections on the development of a physicist
Authors: Chrien R. E.
Published: October 2005

We are here to honor the contributions of Arthur Benade to understanding the physics of musical instruments. These unique contributions were brought to fruition by a set of fortunate coincidences that resulted in a shift from Benade's original career orientation in nuclear physics to one of musical acoustics. As Benade's first student, from 1952 to 1957, I was in a position to view this change at first hand, and perhaps to understand how it occurred better than most others. The coming together of Arthur's deep interest in pedagogy, his broad view of the unity of physics, and the conducive atmosphere present in the department at Case—with its historical ties to acoustics—were responsible for initiating his career in the acoustics of musical instruments. Lessons for us all may be drawn from his ability to combine his vocation and his avocation in a harmonious and productive manner. I would like to share with you my remembrances of this formative time in his professional life.
From musician to listener via first principles and careful observation
Authors: Hoekje Peter L.
Published: October 2005

Many of the elements comprising the acoustics of musical wind instruments have been known since the time of Lord Rayleigh and Helmholtz. Yet, only in the last few decades have the contributions of acousticians been able to weigh significantly with those of artisans (whose names like Boehrn, Conn, Hotteterre, or Sax have become familiar to us through the instrument-making dynasties founded on their acoustic insights) in the creation of fine instruments. Art Benade was a leader in these recent successes. Part of the legacy he leaves us is a methodology for design (or redesign) of wind instruments. It describes the adjustment of tone holes, bore shapes, and reeds in order to improve mode cooperation and decrease energy loss, verified by a series of simple playing experiments. By his unique insight, theoretical results arising from fundamental physical principles are identified with common attributes of “good” instruments. By similar study, he improved the understanding of the perception of sound in rooms. The life work of Art Benade was the isolation of factors of importance to musicians by sound scientific practice, inspired observation, and careful experimentation.
Scattering/diffraction effects of a sound intensity probe incorporating direct particle velocity measurements
Authors: Krishnappa G.
Published: October 2005

Experimental studies were carried out to examine the scattering/diffraction effects of a sound intensity probe that determines particle velocity directly by using two pairs of ultrasonic transmitters and receivers. The measurement techniques employed were to detect the change in the separation distance acoustically of two closely spaced microphones placed in the immediate vicinity of the velocity measuring probe and to determine the accuracy of sound intensity measurements by comparing with sound-pressure level measurements made in the farfield of an acoustic source inside an anechoic room. The results show that there are noticeable changes in the acoustic field in the frequency range 3000–6000 Hz due to the insertion of the probe, and the scattering/diffraction effects tend to increase with increase in the angle of incidence of the sound waves, but do not affect in any significant way the accuracy of sound intensity measurements. Measurement accuracies of the probe are within 1 dB up to 5000 Hz, which includes other sources of errors associated with signal processing such as errors inherent with FFT techniques.
Investigation into the use of the filtered-x LMS algorithm for noise reduction in a duct
Authors: Schuck Peter L.
Published: October 2005

Burgess [J. Acoust. Soc. Am. 70, 715–726 (1981)] simulated an active noise reduction system in a duct. This system utilized a version of the filtered-x LMS algorithm to obtain noise reduction over a wide bandwidth. A similar system has been implemented using the TMS-32020 signal processing chip on a PC expansion board. In the filtered-x LMS algorithm, the reference signal must be filtered by the transfer function between the transversal filter output and the error signal input in order to maintain stability of the LMS weight update. In our system, this transfer function is calculated from the measured response to a maximum length sequence generated by the noise reduction system itself. Performance results are given for this system in a test setup. Some issues regarding practical implementation of this algorithm in fixed point arithmetic will also be discussed.
Accurate estimation of amplitude, frequency, and phase of harmonic signal components using an FFT
Authors: Burgess John C.
Published: October 2005

The signal analyzed using an FFT is seldom identical to the true signal. This can result in inaccurate estimates of amplitude, frequency, and phase of harmonic signals. Using an extension of a method described earlier [J. C. Burgess, “On digital spectral analysis of periodic signals,” J. Acoust. Soc. Am. 58, 556–567 (1975)], it is possible to estimate the true amplitude, frequency, and phase of a harmonic signal with good accuracy. For example, acoustic intensity measurements may require determining the phase difference between two harmonic signals of the same amplitude and frequency. Using the method described, this phase difference often can be estimated with an error less than 0.01%. The method requires use of an optimum data window that can be expressed as a Fourier series having only a few nonzero coefficients.
Sound attenuation in air over water on Puget Sound during temperature inversion and noninversion conditions
Authors: Hauge Jan H.
Published: October 2005

Excess attenuation of sound over a 7500-ft distance was measured on 6 days to determine effects of temperature inversions and wind direction. The tests were conducted using one-third octaves of pink noise at center frequencies of 250, 500, and 1000 Hz. During temperature inversions, excess attenuation downwind was found to be significantly reduced and negative. Results of the tests were used to predict sound levels that would be received at island residences and a bird sanctuary under a proposed industrial use of the mainland shoreline.
Model scale testing of outdoor noise propagation from a power plant
Authors: Putnam Robert A.
Published: October 2005

A proposed cogenerating power plant of 70-MW capacity is to be located in an urban setting and will be subject to stringent environmental noise emission criteria. A four-cell forced draft cooling tower is included in the plant design. Computer modeling of cooling tower noise propagation to affected neighboring residences involved significant uncertainties due to the complex shapes of power plant building elements and existing surrounding buildings. Without a finished facility in which to perform full-scale field tests, the next best thing is a scale model test. This paper will discuss the specifics of the 1/20th scale test setup, materials, selection, instrumentation, test execution, some problems and some lessons learned. The results of the test will be given in terms of the differences in octave band sound-pressure levels between an unobstructed free-field value and the modeled in situ value, at several receptor positions. The test enabled the specification of more precise sound attenuating elements for the cooling tower fans and inlets in order to comply with the governing regulations.
Utilizing the form functions for determining the physical parameters of elastic solid spheres
Authors: Yen N. , Dragonette Louis R.
Published: October 2005

An approach is described to determine the density and the longitudinal and the shear velocities of elastic solid spheres based on their farfield response (the form function) in an insonified acoustic field. The processing scheme uses the information extracted from the characteristics of the form function within a finite frequency range. In particular, it is found that the rate of phase change with respect to frequency in the form function reveals three distinct types of reradiated modes, which are associated with their underlying physical causes. Their separated physical parameters can thus be determined accordingly. Examples with solid spheres constructed from different materials are used to illustrate the practical utilization of this study.
Broadside and end-on resonance scattering from submerged high-aspect ratio targets for several elastic materials
Authors: Überall H. , Werby M. F.
Published: October 2005

Broadside and end-on scattering from solid elastic spheroids composed of aluminum, steel, and WC is examined. The spheroids range in aspect ratio from 4 to 10 with a kL/2 range out to 26. A comparison of the form functions for the different materials shows that the ratios of the kL/2 values at resonances are equal to the ratio of the Rayleigh phase velocities of the respective materials and that the end-on and broadside resonance locations are in accordance with the phase matching method of Überall et al., which is based on the leaky Rayleigh type wave interpretation of resonances. Further, it is shown that the resonance locations are only sensitive to the shear speed and that it is possible to generate resonances that occur end-on at all angles including broadside, which is only consistent with the Rayleigh wave interpretation of resonances.
Acoustic resonance spectra of a finite cylindrical shell
Authors: Maze G. , Lecroq F. , Izbicki J. L. , Ripoche J.
Published: October 2005

Previous studies have explained acoustic scattering from an infinite cylinder or a sphere. The scattering depends strongly on resonances that are related to the propagation of circumferential waves when the acoustic axis is perpendicular to the cylinder axis or the propagation of guided waves when the insonification is oblique. The method of isolation and identification of resonances (MIIR) developed in our laboratory is used to study acoustic scattering from a finite cylindrical shell bounded by two plane disks. The acoustic beam diameter is larger than the target dimensions. When the acoustic beam axis is perpendicular to the target axis, the resonances observed on the resonance spectrum are identical to those observed with an infinite cylindrical shell. When the acoustic beam axis is not perpendicular to the target axis, the resonances are more numerous and, for certain incidence angles, next resonances have the same mode.
Bounded beam transmission across water/sand interface. Part 1—Experiment
Authors: Satkowiak L. J. , Williams K. L.
Published: October 2005

A series of measurements was made to investigate the effect of the water/sediment interface on a propagating acoustic signal. Under nearly laboratory conditions, data were collected mapping out the sound-pressure field in a homogeneous sand for a variety of nonlinear and linear sources. The data were collected using the following sources: a truncated parametric source, a saturation limited parametric source with effective length less than the sender-interface distances, and a linear source, all operating at a frequency of 20 kHz. The data were taken at grazing angles that ranged from well-above to well-below the critical angle for the sediment. Based on the data collected from the in-sediment pressure field, contours were obtained detailing the magnitude and direction of the pressure wave in the sediment. These pressure field contours, as well as experimental procedures and analysis techniques, will be presented. A comparison with theoretical predictions will be made in the following paper.
An iterative solution to acoustic scattering by rigid bodies
Authors: Schuetz Luise , Shirron Joseph J. , Kleinman Ralph
Published: October 2005

The scattering problem is formulated as an integral equation over the scattering surface. A solution to the equation is given in a convergent Neumann series where the convergence depends on a parameter α. The boundary element method is used to obtain an approximation to the solution, and the resulting matrix equation is solved by an iterative technique. Results are given for several different geometries and frequencies. A comparison of solution time and accuracy to direct methods such as Gaussian elimination is presented, showing the iteration to be more economical in most cases of practical interest. Finally, there is a short discussion on determining the iteration parameter α and its effects on the rate of convergence.
Determination of the reflection coefficient and the cross-sectional area function from high-frequency pressure measurements in the ear canal
Authors: Rabbitt R. D.
Published: October 2005

At moderate to high frequencies, incoming and outgoing pressure waves combine to form standing waves in the ear canal. The exact form of the pressure distribution depends on the geometry of the ear canal and on the magnitude, and phase, of the reflected wave relative to the incoming wave. An asymptotic theory describing this interaction is combined with pressure measurements in the ear canal in order to determine the reflection coefficient at the eardrum, the cross-sectional area function of the ear canal, and the relative phase of the reflected wave. The theory is based on a high-frequency multiscale solution of the one-dimensional horn equation and is shown to agree well with experimental measurements of standing wave patterns and with the distribution of phase in the ear canal. Since the absorption of energy at the eardrum is determined, this method is particularly well suited to determine the input to the ear at high frequencies. [Work supported, in part, by the Whitaker Foundation.]
Measured frequency responses of the peripheral auditory organs in goldfish
Authors: Hastings Mardi C. , Rogers Peter H.
Published: October 2005

The frequency responses of the primary peripheral auditory organs in eight goldfish (Carassius auratus) were measured using a recently developed noninvasive vibration detection system based on ultrasound and having a spatial resolution of 0.28 mm [M. Cox and P. H. Rogers, J. Vib. Acoust. Stress Reliability Design 109, 55–59 (1987)]. The fish averaged 4.5 cm in standard body length and 3 g in weight. They were freely suspended underwater and anesthetized during the measurement process. Most of the responses were recorded in vivo; however, some of the fish did not recover from the anesthesia and may have died during the procedure. The results are the first to verify the existence of a high-pass filtering mechanism via the Weberian ossicles, as previously postulated in the literature. [Work supported by ONR.]
Behavior of two major organ of Corti proteins during development and maturation of the cochlea
Authors: Thalmann Isolde , Kraus Peter , Varghese Jogy , Comegys Thomas H. , Thalmann Ruediger , Zenner H. P.
Published: October 2005

Two highly acidic, low molecular weight proteins, present in very high concentration in the organ of Corti (OC) and termed OCP-I and OCP-II [I. Thalmann et al., Arch. Otorhinolaryngol. 226, 123–128 (1980)] have been previously described. The behavior of these proteins during the post-natal development in the rat cochlea has now been determined. On the 6th day post partum (pp), only trace amounts of the substances are present. The concentration of OCP-I and OCP-II increases most rapidly between days 12 and 14 pp, and the proteins approach adult levels by day 18 pp. The sharp increase of OCP-I and OCP-II occurs at approximately the same time as the sudden increase of the endolymphatic potential on day 13 pp [S. K. Bosher and R. L. Warren, J. Physiol. 212, 739–761 (1971)]. It is of interest that a major basilar papilla-specific protein in the chick increases in step with the onset of auditory function during embryonic development [J. C. Oberholtzer et al., Hear. Res. 23, 161–168 (1986)]. This protein is similar but not identical in its electrophoretic pattern to OCP-II. The behavior of OCP-I and OCP-II will be compared with the pattern of other important proteins such as actin, tubulin, and calmodulin.
Perturbation of cochlear microphonics by an intracellular electrode in the organ of Corti
Authors: Zwislocki J. J. , Smith R. L.
Published: October 2005

Recording the receptor potentials of cochlear inner and outer hair cells in situ has become an essential part of cochlear research. To reach the cells, the recording electrode has to traverse parts of the organ of Corti. Such intrusion may affect the cochlear micromechanics. This possibility was tested by recording scala-media CM in the second cochlear turn in Mongolian gerbils. A small hole was drilled in the cochlear bony capsule above the basilar membrane, and an intracellular electrode was made to traverse Hensen's cells all the way to the OHCs. A second electrode placed in the endolymph recorded CM amplitude and phase as a function of sound frequency. Our results indicate that an intracellular electrode lodged in the organ of Corti can produce substantial changes in CM tuning. This means that the cochlear micromechanics was perturbed. [Work supported by Javits Grant NS 03950.]
Indirect evidence for the absence of electrotonic coupling between hair and support cells in the mammalian cochlea
Authors: Oesterle Elizabeth , Dallos Peter
Published: October 2005

Gap-junctional complexes link goldfish and lizard hair cells with adjacent supporting cells [Hama, J. Neurocytol. 9, 845–860 (1980); Nadol, Mulroy, Goodenough, and Weiss, Am. J. Anat. 147, 281–302 (1976)]. Lizard hair cells and support cells appear to be electrically coupled [Baden-Kristensen and Weiss, Hear. Res. 8, 295–315 (1982)]. In mammals, anatomical evidence suggests the absence of gap-junctional complexes between hair cells and support-cell neighbors, but suggestive membrane specializations have been observed [Gulley and Keese, J. Neurocytol. 5, 479–507 (1976); Nadol, Ann. Otol. 87, 70–80 (1978)]. Horseradish peroxidase marking and intracellular recording techniques were utilized to determine the origin (s) of sound-induced potential changes in supporting cells of the organ of Corti. Recordings were made in the low-frequency region of the adult guinea-pig cochlea, an in vivo preparation. Response characteristics of support cells to tone bursts at various sound levels and frequencies were compared with hair-cell responses (IHC and OHC) and potentials recorded in organ fluid spaces. Comparisons of the harmonic content of the responses, magnitude, and phase of the fundamental component, and the magnitude of de-response components suggest a lack of electrotonic coupling between mammalian hair cells and support cells. [Work supported by NIH Grant NS-08635.]
Neurotransmitter and peptide neuromodulator candidates in haircell and nerve fractions of the saccular macula of the rainbow trout
Authors: Drescher Marian J. , Drescher Dennis G.
Published: October 2005

An epithelial sheet of 30 000–40 000 hair cells, detached from the basal lamina of the trout saccular macula, has been analyzed for primaryamine and N-acylated compounds by cation-exchange HPLC. This haircell fraction (HC), greatly reduced in supporting cells and neural elements, was simpler in primary-amine composition than the saccular nerve fraction (SN), which included afferent and efferent neurons and Schwann cells. The HC contained more phosphoserine and phosphoethanolamine, or co-eluting components, per microgram protein than SN [cf. M. J. Drescher and D. G. Drescher, Comp. Biochem. Physiol. 86A, 553–558 (1987)], and ten times more beta-alanine. Of the excitatory amino acids in HC, glutamate was present in highest concentration, and was significantly elevated (p < 0.02), 2.6-fold, above levels determined for SN, consistent with published efflux and release studies [M. J. Drescher, D. G. Drescher, and J. S. Hatfield, Brain Res. 417, 39–50 (1987)]. Histidine-containing peptides in millimolar concentrations appeared uniquely partitioned: Carnosine and homocarnosine, in a ratio of 10:1, respectively, were associated with SN, while a third histidine-containing component, tentatively identified as N-acetyl histidine, was associated primarily with HC. Possible involvement of histidine-containing compounds as neuromodulators will be discussed. [Work supported by NIH Grant NS 16166.]
Quantitative light microscopic comparison of cochlear nerve morphology in Sprague-Dawley and Brown Norway rats
Authors: Hoeffding Virginia , Feldman Martin L.
Published: October 2005

Cochlear nerve morphology was studied in young adult albino (Sprague-Dawley) and pigmented (Brown Norway) rats. Following perfusion of the animals with mixed aldehydes, blocks including the cochlear nerves were removed, embedded in Araldite, and sectioned in a plane transverse to the longitudinal axis of the nerve. Analysis of the material included counts of normal and degenerating fibers and of glial cell nuclei, and measurements of vascularity and of the nerve cross-sectional area. The median number of normal fibers in the Sprague-Dawley rats was 21 216; in the Brown Norway rats it was 20 186. There were no statistically significant differences between the two strains in numbers of normal fibers, degenerating myelin sheaths, or glial cell nuclei, or in the cross-sectional areas of the nerves. Vascular area density (VAD) was significantly higher in the Sprague-Dawley rats. The median (VAD) in that strain was 0.0149, while in the Brown Norway rats the median (VAD) was 0.0099. [Work supported by NIH Grants AG 00001 and T32 NS07152.]
Forward masking of the compound action potential: Thresholds for the detection of the N1 peak
Authors: Relkin Evan M. , Smith Robert L.
Published: October 2005

A computerized two-interval forced-choice method was used to measure the threshold for detection of the N1 peak of the compound action potential (CAP) recorded at the round window of the chinchilla in response to a 23-ms probe tone. A 100-ms, pure-tone masker of equal frequency preceded the probe tone. Threshold shifts produced by the masker were measured as the intensity of the masker and the time delay between the masker and the probe were varied. The techniques differ from prior studies in that forward masking of the compound action potential has been quantified as shifts in detection thresholds rather than decrements in the magnitude of the N1 peak. Results were compared to analogous measures for single neurons in the auditory nerve [E. M. Relkin and D. G. Pelli, J. Acoust. Soc. Am. 82, 1679–1691 (1987)] and analogous psychophysical measures of forward masking. Preliminary findings indicate that forward masking of the CAP more closely corresponds to that observed psychophysically than does the forward masking observed in the response of a single neuron. [Work supported by the Deafness Research Foundation and NIH.]
Auditory nerve fiber responses predict the discriminability of VOT syllables
Authors: Sinex Donal G. , McDonald Lynn P.
Published: October 2005

Responses of chinchilla auditory nerve fibers to synthesized syllables differing in VOT were obtained. A continuum heard as /da/∼/ta/ was used. Many neurons responded with an increase in average discharge rate or with a change in synchronized response whose latency matched the nominal stimulus VOT. Response latency was treated as a random variable. For each VOT pair, a statistic analogous to d' was calculated from the distribution of the difference between two random variables. Thresholds for ΔVOT were interpolated from psychometric functions based on this statistic. Thresholds were lowest for standard VOTs of 30–40 ms, but were highly dependent on the direction of change from the standard. These characteristics were also typical of the chinchilla's psychophysical thresholds for ΔVOT, reported by Kuhl [J. Acoust. Soc. Am. 70, 340–349 (1981)]; in addition, the quantitative agreement between neural and behavioral thresholds was usually very good. For this VOT continuum, discriminability reflects the precision of stimulus coding at the level of the auditory nerve. [Work supported by NINCDS.]