bluuebunny/crossref_metadata_2025 huggingface dataset:
Gaussian ray bundles for simulating shallow-water torpedo reverberation
Authors: Weinberg Henry , Keenan Ruth E.
Published: October 2005

A range-dependent propagation model was developed to simulate shallow-water torpedo reverberation. The model is based on Gaussian ray bundles in the form ‖P(r,z)‖2=[β/√2πσ(r)prr]exp(−0.5[(z−zr)/ σ(r)]2), where r is the horizontal range from the source to the field point, z is the vertical depth of the field point, zr is the vertical depth along a central ray, pr is the horizontal slowness along a central ray, β depends on the source, and σ(r) is an effective standard deviation given by σ(r)=(1/2)max(Δzr,8λ). Here, Δzr is the vertical distance between two adjacent rays and λ is the wavelength at the field point. [Work supported by the Naval Sea Systems Command (PMS-402 and PMS-406) and the Office of Naval Research (ONR-321).]
Nonadiabatic ocean acoustic environments and the flux density derivative
Authors: Ruppel Timothy H.
Published: October 2005

The accuracy of the adiabatic approximation is known to be suspect when applied to certain environments, particularly areas along the continental shelf. An issue in these environments is the degree to which the adiabatic assumption is valid. Transmission loss calculations using both parabolic equation and coupled mode models show that for steep slopes much more energy reaches the shelf from deep water than predicted by the adiabatic approximation. It has been shown that rapid variations in the energy flux as calculated from a parabolic equation model often indicate a breakdown of the adiabatic approximation and, therefore, significant mode coupling. This study connects these observations to the propagation physics and the standard coupled mode equations. The limits and strengths of using variations in the energy flux as an indicator of mode coupling are outlined. It is shown that this method of determining the degree of validity of the adiabatic assumption is valid in a large class of environments.
Optimum wideband detection of solid spherical objects of uncertain composition in the vicinity of a smooth sandy bottom
Authors: Wazenski M. , Alexandrou D. , Nolte L. W.
Published: October 2005

Wideband detection of solid spherical elastic objects is approached via optimal detection and estimation theory in conjunction with acoustic scattering models for both the object and the seafloor. The objective is the time domain development of full field optimal decision methods for high-frequency active detection of a target in the vicinity of the seafloor. This parametric approach incorporates the inherent uncertainty surrounding the physical composition of both the object and seafloor. The acoustic model used for the spherical object is the well-known modal series solution and is parameterized by object size, density (object and medium), compressional wave speed (object and medium), and shear wave speed. This deterministic model is used to predict the target signature measured at an array of sensors. Acoustic modeling of the seafloor is performed through application of a modified point-scatterer model. This model provides a physical mechanism for describing the spectral scattering properties of the seafloor and is used to predict the spatial and temporal coherence of the scattered sound field. Illustrative detection examples are presented using both simulation and tank experimentation. Performance measurements are given by receiver operator characteristic (ROC) analysis. [Work supported by ONR: Ocean Acoustics.]
Computer modal analysis of percussion sounds: A preliminary study
Authors: Beauchamp James W.
Published: October 2005

Short time Fourier transform methods can be applied to the problem of modal analysis of percussion sounds, which are well known to contain inharmonic partials. One problem is that the Fourier transform is equivalent to a harmonically spaced filter bank, so it is not possible to position filter centers at arbitrary positions. Another problem is that, typically, percussion modes are closely spaced while their amplitudes change rapidly, which plays havoc with frequency versus time resolution limitations. For widely spaced modes, the first problem is solved by choosing the base analysis frequency to be an integral common divisor of the modal frequencies, so that each mode corresponds to a unique equivalent filter. When modes become too dense, they cannot be resolved, and bands of modes must be treated as indivisible entities in order to conserve the temporal behavior. For example, if a 20-ms time resolution is desired, modes no closer than 50 Hz can be resolved. Results and ramifications of these limitations for analysis of percussion instruments such as tubular bells, timpani, and cymbals will be presented and discussed.
Clock chimes: Their spectra and their pitches
Authors: Espe David , Lin Jian-Yu , Hartmann William Morris
Published: October 2005

The chimes of contemporary 7-foot grandfather clocks are made from steel rods, tapered at their clamped ends so that modal frequencies are stretched compared to thin-rod theory. Melody rods, 39–56 cm in length, lead to matchable pitches, nominally in the octave from 220 to 440 Hz. Hour-strike rods, 59 and 67 cm in length, produce pitches that are less stable. Chime tones were digitally synthesized according to both measured and idealized frequencies, amplitudes, and decay rates. Pitch matching results were compared with the pitch model of Terhardt etal. [J. Acoust. Soc. Am. 71, 679–688 (1982)]. Both experiment and model show competition between spectral and virtual pitch and between cues at the nominal strike tone and the minor third. Generally the experiment finds the range of virtual pitch to be higher than predicted by the model. [Research supported by the Sligh Clock Company, Zeeland, Michigan, by the NIDCD, and by the NSF Research Participation for Undergraduates Program.]
Signal processing for computer-assisted instruction of sight singing
Authors: Smith Lloyd , McNab Rodger
Published: October 2005

SST (Sight Singing Tutor) is a computer-assisted instructional program to teach the skill of singing melodies at sight. The program displays a melody on the screen, accepts acoustic input from a user, then evaluates the user’s attempt to sing the melody. SST’s primary signal processing tasks are frequency identification, note segmentation, and matching the singer’s input against the test melody. SST tracks frequency using the well-known Gold–Rabiner algorithm [J. Acoust. Soc. Am. 46, 442–448 (1969)], averaging over 20-ms frames in order to compensate for sampling error at higher frequencies. Notes are segmented using smoothing and grouping procedures based on frequency differences calculated in cents. The user’s melody is matched against the test melody using a dynamic time warping (DTW) algorithm designed to match discrete melodic sequences [Mongeau and Sankoff, Comput. Humanit. 24, 161–175 (1990)]. SST displays the DTW match and presents a score, which takes into account both pitch and rhythm. SST works equally well with both male and female voices and allows the singer to sing the melody in his or her most comfortable octave; the prototype system has been shown to accurately identify and display notes ranging from F2 (87 Hz) to A5 (880 Hz).
An ad hoc method for control of generator noise
Authors: Wetherill Ewart A.
Published: October 2005

A machine shop is housed in the same building as two large motor generators. Because of the need for overhead crane access to both facilities they are separated only by a partial-height wall. The resulting work environment is noisy and unpleasant although below the OSHA requirements for hearing protection. This paper describes two feasible methods of acoustical separation, one of which was aceptable to the owner but which has not yet been executed.
Methods of group evaluation of noise load in industry
Authors: Menshov Alexander A. , Levin Mark V.
Published: October 2005

Methods of evaluation and regulation of individual noise load for the analysis of its interrelation with quality, labor productivity, and emergency situations at production areas have been elaborated in detail. It is much more difficult to evaluate noise load for the whole group of workers even within the boundaries of one technological zone. For the production area attestation, from the viewpoint of the noise factor, it was proposed that the noise load of a group of workers should be evaluated as a percent ratio of the number of persons whose noise load is higher than the standard, to the total number of workers in the evaluated group. This index can be called the ‘‘coefficient of noise attestation’’ (CNA). For the analysis of the interrelation between quality, labor productivity, emergency situations at the production areas, and the noise load, it is proposed that the latter be evaluated as a quotient from the division of the sum of the noise load excesses for each of the workers by the number of workers in the evaluated group. This second index can be called the ‘‘coefficient of noise load on workers’’ (CNLW). These coefficients are used in new standards of Ukraine (N 2325 ‘‘Noise. Terms and definitions,’’ 1993), in a draft standard of Ukraine (‘‘Noise. Methods of definition of noise load of workers,’’ 1995), and in the analysis of the interrelation between emergency situations at thermal power plants of Russia and Ukraine and the noise load on the workers (1979–1989), while attesting working places at the enterprises of building materials in Kiev (1992–1994).
Blast sound propagation over hilly land
Authors: Isei Takehiro , Imaizumi Hiroyuki , Kunimatsu Sunao , Kinoshita Michiaki
Published: October 2005

A blast sound propagates over a long range, because of its large sound power of sources and low-frequency components. Blasting operations are often conducted at a hilly side and as a result, sometimes the sound of the blast influences the life environment beyond the hilly undulations. At both hilly sites with heights of up to several tens of meters and flat lands, excess attenuation of blast sound was measured at points of several hundred meters away. Frequency spectrums of excess attenuation beyond the hilly side show that (1) up to around 100 Hz, excess attenuation increases in proportion with frequency, and for more than 100 Hz, it shows mostly constant values of around 40 dB; (2) shapes of frequency spectrum of the excess attenuation show similar pattern with the ones of flat land; and (3) shielding effects of hills mainly appear at the frequency range around 100–250 Hz. From these results, the authors discuss the possibility of sound propagation modeling by extending usual models for flat land.
Preliminary analysis of SWellEX-3 noise characteristics
Authors: Pflug Lisa A. , Jackson Pam M. , Ioup Juliette W. , Ioup George E.
Published: October 2005

Higher-order moment analysis is performed for segments of data taken during the SWellEX-3 experiment, which was conducted off the Southern California coast in 1994. One SWellEX-3 objective was to provide a controlled data set for the purpose of improving understanding of detection in shallow water dominated by local shipping noise. Ambient noise and radar ship tracks were recorded for two full weekends over which the shipping character of the area changed dramatically. Second- and higher-order detection performance depends on the statistical character of the noise including the moment properties. As a prelude to higher-order detection evaluation, segments of data during times of light and heavy nearby shipping are analyzed for second- and higher-order moments, stationarity, and directionality. [UNO research supported by Office of Naval Research.]
Features of the seismoacoustic ambient noise field in a near-shore environment
Authors: D’Spain Gerald L. , Hodgkiss William S. , Berger Lewis F. , Kuperman William A.
Published: October 2005

This paper presents the features of the 1- to 750-Hz ambient noise field recorded during MPL’s adaptive beach monitoring experiment, a near-shore seismoacoustic experiment off the Camp Pendleton Marine Base north of San Diego, CA. Signal propagation characteristics in this environment are presented in a companion paper. The data were recorded by two nearly orthogonal, horizontal hydrophone arrays located 3.4 km offshore in 20-m water. The most predominant aspect is the sounds created by biologics, particularly night-time ‘‘cycling’’ choruses of fish. Ideas on the use of these sounds for determining the geoacoustic properties of the ocean bottom are discussed. Also present at night are strong lines at 85 Hz and its two higher harmonics, associated with water pumps on the marine base used to fill wells in the surrounding hills. A still-puzzling feature is the broadband pulses (50–200 Hz) that occur at a 7.5-s repetitition period; they possibly also are of a biological nature. Fluctuations in the infrasonic band are associated with ocean surface wave propagation, thereby providing a means of determining the ocean surface wave directional spectrum. Finally, by judicious selection of data, noise generated by breaking surf can be measured. [Work supported by ONR, Code 32.]
Characterizing parameter landscapes for poroelastic media
Authors: Lingevitch Joseph F. , Collins Michael D.
Published: October 2005

There is presently a great deal of interest in modeling ocean sediments as poroelastic media. One of the topics of particular interest is matched-field inversion for sediment parameters. This paper will investigate the resolvability of poroelastic parameters in ocean sediments using acoustic sources and receivers located in the water column. The eigenvectors and eigenvalues of the covariance matrix of the gradient of the cost function indicate the most important underlying parameters as well as the degree of coupling between parameters [M. D. Collins and L. Fishman, ‘‘Efficient navigation of parameter landscapes,’’ J. Acoust. Soc. Am. 98, 1637–1644 (1995)]. This information is useful for designing effective experiments for resolving the desired parameters. The information in the covariance matrix can be used to determine the most effective frequencies and array configuration and to optimize the performance of the inversion at each frequency. Wave-number integration and parabolic equation models are available for solving the forward problem [M. D. Collins, W. A. Kuperman, and W. L. Siegmann, ‘‘A parabolic equation for poro-elastic media,’’ J. Acoust. Soc. Am. 98, 1645–1656 (1995)].
Determining sediment absorption using ambient noise in shallow water
Authors: Carbone Nicholas M. , Deane Grant B. , Buckingham Michael J.
Published: October 2005

The ambient noise field in shallow water interacts strongly with the underlying seabed. As a consequence, the vertical directionality of the noise is largely determined from the characteristics of the seabed. In previous research, this property has been utilized to perform inversions for the compressional and shear wave speeds in hard seabeds. Soft seabeds predominate along continental shelf regions. In these cases, the absorption of compressional waves in the sediment is an important determinant of the noise field statistics which creates a measurable asymmetry in the vertical directionality. This asymmetry has been used as the basis of an inversion methodology, whereby the compressional wave absorption is estimated from measurements of the noise. The technique uses a broadband measurement from a vertically separated hydrophone pair at a fixed location. The ambient noise method yields an absorption estimate representing an average over range and depth. The technique represents a new means of estimating seabed absorption which leaves the sediment undisturbed. Absorption estimates obtained from inversions of ocean noise data taken above various soft seabeds will be presented. [Work supported by ONR.]
A numerical solution of the parabolic elastic wave equation
Authors: Nagem Raymond J. , Lee Ding , Li Gongquin
Published: October 2005

Based on the parabolic equation approximation, a set of equations has been developed for three-dimensional time-harmonic wave propagation in an elastic medium. The elastic equations for the scalar and vector potentials are written in a matrix form which is a direct counterpart to previous work on the scalar wave equation for a fluid medium. An ordinary differential equation (ODE) method in conjunction with a finite-difference scheme leads to a stable marching procedure. One feature of this approach is that every finite-difference discretization results in a tridiagonal system of equations; these equations can be solved efficiently by recursive formulas. This paper reports the computational results which are used to check (1) the stability of the marching scheme, and (2) the accuracy of the elastic model. Accuracy and validity are verified by comparing the numerical results of the finite-difference method with a far-field analytic solution in an unbounded medium.
Quiet unlined HVAC ductwork: Using active silencing to obtain NC-35 in buildings without fibrous materials
Authors: Wise Steve , Gelin Lawrence J. , Burlage Kirk G. , Dineen Susan H.
Published: October 2005

Fan noise in HVAC ducts has traditionally been attenuated with fibrous internal duct liner or with passive silencers constructed with porous fill material. Now, with active noise control, it is possible to cancel the loudest frequencies in the fan noise spectrum using inert components on the duct-microphones and loudspeakers. Proper selection of fan type, optimal duct design, and appropriate active noise control system configuration can achieve acceptable noise levels in all octave bands in the sensitive building spaces. Many recent examples of actual installations are given, including systems on air handlers up to 25 000 cfm capacity. Systems are applied, not only the central station air handlers, but also to secondary fans such as those used in fan-powered VAV boxes. Application considerations such as duct design and energy efficiency will be noted in this paper along with the specific room acoustical requirements and system performance.
Kidney tubular epithelial cell injury in shock wave lithoripsy: The search for an appropriate in vitro model
Authors: McAteer James A. , Evan Andrew P. , Lingeman James E. , Andreoli Sharon P.
Published: October 2005

Renal injury is a documented consequence of SWL and includes direct damage to the tubular epithelium. The factors of SW administration that contribute to cell injury are not fully understood, nor have the mechanisms responsible for cell damage been adequately characterized. Numerous laboratories have used cultured cells to assess SW cytolytic potential. For the most part, these studies have employed fully dissociated cells. To test the idea that cell polarity and cell–cell interactions influence response to SW, the proximal tubulelike line LLC-PK1 was prepared to allow isolation for SW exposure as a polarized monolayer (PM). SW response of PM was compared to dissociated cells. SW exposures were performed with an unmodified HM3 (electrohydraulic). Viability of dissociated cells descrased with increased SW number at 18 kV but was equivalent when kV was varied (14–22 kV). ATP depletion was greater for freshly dissociated cells than for isolated cells from stable suspension culture. PM showed diminished lytic injury (LDH release) compared to dissociated cells. These findings indicate that the nature of an invitro preparation influences the characteristics and severity of cell injury, and that polarized epithelial monolayers can be used to model the tubular cell response to shock waves. [Work supported by NIH P01 43881.]
Biological effects of lithotripter fields
Authors: Dalecki Diane , Child Sally Z. , Raeman Carol H. , Carstensen Edwin L.
Published: October 2005

Lithotripsy has become a common procedure for the treatment of kidney stones. Fields of lithotripters are capable of producing both stone distintegration and damage to soft tissues. Thresholds for biological effects of lithotripter fields include hemorrhage in mammalian lung (∼1.5 MPa), kidney (3–5 MPa), and intestine (1–3 MPa), malformations in the chick embryo (<10 MPa), premature ventricular contractions in the frog heart (5–10 MPa), and killing of Drosophila larvae (<1 MPa). Tissues containing gas bodies are particularly susceptible to damage. Pulsed ultrasound can also produce comparable soft-tissue damage and the similarity of threshold pressures for lithotripter and pulsed ultrasound exposures suggests that the same mechanisms may be involved in both phenomena. Cavitation and purely mechanical forces have been investigated as possible mechanisms for these bioeffects.
A durable, wide-bandwidth lithotripsy hydrophone
Authors: Holz Byron , Everbach E. Carr
Published: October 2005

In order to balance wide bandwidth with durability, a hydrophone for lithotripsy research was developed using disposable elements of 9-μm-thick PVDF copolymer film. Each element, which measures 1 cm × 10 cm and is stretched across a Plexiglas frame, contains 0.2-mm-wide electrodes overlapping in a crosshair pattern at the element center. When an element fails, it may be quickly replaced. To avoid the need for recalibration with each replacement, the use of hysteresis poling ensures constant sensitivity of elements [E. Carr Everbach, J. Acoust. Soc. Am. Suppl. 1 87, S128 (1990)]. Electronics located in the frame include a wide-bandwidth preamplifier and gating circuitry to prevent saturation by the electromagnetic pulse from a spark-gap lithotripter. This design provides the needed bandwidth to resolve shock wave frequency components beyond 100 MHz, as well as the durability and spatial resolution necessary to map the acoustic field within a lithotripter. [Work supported by an NSF PFF.]
Further study of the effects of shear viscosity on inertial cavitation thresholds
Authors: Allen John , Roy Ronald A. , Church Charles C.
Published: October 2005

Initial research [Allen etal., J. Acoust. Soc. Am. 96, 3306(A) (1994)] on accessing the effects of shear viscosity on inertial cavitation thresholds has been extended in order to further explicate previous results. Thresholds for inertial cavitation in water and biological media modeled as a viscous fluid were calculated using a numerical implementation of the Gilmore equation for adiabatic bubble oscillations [Church, J. Acoust. Soc. Am. 83, 2210–2217 (1988)]. The threshold criterion was chosen to be a bubble collapse temperature of 5000 K as to facilitate comparison with the analytical theory of Holland and Apfel [IEEE-UFFC 36, 204 (1989)]. The scaling of the calculated pressure thresholds with initial bubble radius was previously not sufficiently explained by linear resonance theory. The addition of calculations of the ‘‘nonlinear resonance’’ sizes, however, more adequately explains this scaling. Furthermore, the nonlinear resonance size is shown to be a more accurate indicator of the bubble sizes most likely to undergo inertial cavitation than the linear resonance size. The qualitative physics pertaining to these additional results is highlighted along with comparisons to recent experimental measurements [Zheng etal., J. Acoust. Soc. Am. 95, 2855(A) (1994)]. [Work supported by NIH through Grant No. RO1 CA39374.]
Kidney size is a determinant of structural/functional injury following shock wave treatment of pigs
Authors: Evan Andrew P. , Connors Bret A. , Willis Lynn R. , Trout Anne , Lingeman James E.
Published: October 2005

It has been suggested that kidney size is a risk factor for increased shock wave lithotripsy- (SWL) induced damage. This relationship was investigated in pigs of two different ages; ten weeks of age (group 1) and five weeks of age (group 2). Each pig received 2000 shocks, 24 kV to the right kidney. Glomerular filtration rate (GFR), PAH clearance and extraction were measured 1 h before and 1 and 4 h after SWL treatment. The kidneys were harvested at the end of the clearance study. Values for GFR, PAH clearance, and extraction were reduced in the shocked kidney of both groups 1 h post-SWL. Calculated values for true renal plasma flow showed a greater reduction in the treated kidneys of group 2 versus group 1. The degree of subcapsular hemorrhage and intraparenchymal bleeding and tubular disruption was more extensive in group 2 versus group 1 treated kidneys. The data document the degree of structural and functional injury induced by SWL and support the hypothesis that the effect of SWL is greatest in kidneys having the least mass. [Work supported by NIH Grant No. P01 DK 43881.]
Effects of frequency-dependent absorption on the propagation and attenuation of high-intensity acoustic waves containing shocks
Authors: Khokhlova Vera A. , Sapozhnikov Oleg A. , Averkiou Michalakis A. , Crum Lawrence A.
Published: October 2005

Shock waves used in extracorporeal lithotripsy and ultrasonic surgery are greatly influenced by thermoviscous losses in the tissue. The influence of the frequency dependence of the absorption coefficient on nonlinear wave distortion and energy attenuation has not been investigated in detail up to now. For absorption frequency dependence other than quadratic, the corresponding nonlinear evolution equation is often complicated and thus frequency domain methods are more effective. The presence of the shock, however, makes this analysis time consuming due to the large number of spectral components needed in the numerical calculation. To avoid this complexity, a semianalytical method that enables calculations with relatively few harmonic components is used. Propagation in media with various power law absorption is considered. It is shown that energy attenuation of an initially sinusoidal wave in a medium with linear power law absorption is quite similar with that in a medium with quadratic power law absorption, even though the waveforms are quite different. The effect of selective absorption of a certain harmonic component is also investigated. It is shown that second harmonic selective absorption does not prevent shock formation, but results in much less energy attenuation over large distances. [Work supported by NIH, FIRCA, and RFFI.]
Relaxation dynamics of spontaneous otoacoustic emissions perturbed by external tones: Response to a single tone at multiple suppression levels
Authors: Murphy William J. , Tubis Arnold , Talmadge Carrick L.
Published: October 2005

The relaxation dynamics of spontaneous otoacoustic emissions (SOAEs) interacting with an external tone have been successfully described using a Van der Pol limit-cycle oscillator model [Murphy etal., J. Acoust. Soc. Am. 97, 3702–3711 (1995a) and Murphy etal., J. Acoust. Soc. Am. 97, 3712–3720 (1995b)]. The theory developed in Murphy etal. (1995a) includes the possibility for multiple external tones to produce suppression of the oscillator amplitude. The relaxation dynamics are dependent upon the final state of the oscillator. The oscillator’s rate of transition between two suppressed states is a function of κ22r1, the final amount of suppression and the negative damping parameter r1. Data were collected from an SOAE interacting with a single frequency ipsilateral suppressor. Transitions between different suppressed states were achieved by adding or removing signal at the same frequency. The ability of the relaxation dynamics theory to describe this special case will be examined.
Effects of repetition rate, phase, and frequency on the auditory brain-stem response in newborn neonates and adults
Authors: Parthasarathy T. K. , Borgsmiller Paul , Cohlan Barbara
Published: October 2005

Effects of repetition rate, phase, and frequency on wave V latency of the auditory brain-stem response (ABR) were evaluated and compared in ten normal newborn neonates and adult subjects. Single cycle sinusoids at 0.25 and 2.0 kHz were presented monaurally via an insert earphone at 75 dB nHL, using either a condensation (C) or a rarefaction (R) stimuli at two rates, 11.1 and 55.5/s. The stimulus phase by frequency interaction was significant. In both neonates and adult subjects, the ABR wave V latency for R stimuli was significantly shorter compared to C stimuli at 0.25 kHz. However, the effect of phase on wave V latency was insignificant at 2.0 kHz. Furthermore, the stimulus rate by age interaction was significant. The ABR wave V latency shift with an increase in repetition rate was significantly greater in the newborn neonates than in the adult subjects.
Directionality of sound-pressure transformation at the pinna of Musdomesticus
Authors: Chen Qi-Cai , Cain David , Jen Philip H.-S.
Published: October 2005

Sound-pressure transformation properties at the pinna of laboratory mice, Musdomesticus, were studied by measuring the sound-pressure level of a continuous tone at a series of frequencies at the tympanic membrane as a function of the position of a sound source under free-field stimulation conditions. The spectral transformation, the interaural spectral difference, the isopressure contours and the interaural pressure difference contours were plotted. Sound-pressure transformation functions showed some prominent spectral notches throughout the frequency range of 10–80 kHz tested. When delivered from some angles within the ipsilateral frontal hemisphere, the sound pressure at the tympanic membrane of certain frequencies may be lower than that determined at the corresponding contralateral angles (i.e., the negative pressure). For each sound frequency tested, there was an angle (the acoustic axis) within the ipsilateral frontal hemisphere from which the delivered sound reached a maximal pressure level at the tympanic membrane. However, the acoustic axis often changed to a new angle after removal of the ipsilateral pinna. Removal of the ipsilateral pinna or modification of pinna posture expanded isopressure contours irregularly and split the 2-dB maximal pressure area into several parts. [Work supported by NIH and HFSP.]
An evoked potential study of directional sensitivity in the inferior colliculus of the laboratory mouse (Mus domesticus)
Authors: Cain David M. , Jen Philip H.-S.
Published: October 2005

Directional hearing of the laboratory mouse was studied by recording 30 evoked potential responses from the inferior colliculus to best frequency (BF) sounds delivered from within the frontal auditory field. Audiograms determined with maximal response amplitude (N=6) and minimum threshold (N=8) showed maximal auditory sensitivity occurring between 10–15 kHz (M±s.d.=11.2 kHz±2.34). For five evoked potentials, amplitude-intensity functions were obtained for seven selected azimuthal angles at 0° elevation. All 35 functions were nonmonotonic but their dynamic range was affected by sound direction. The azimuthal and elevational angles of maximal auditory sensitivity (the response centers) of 25 evoked potentials responses, were always located in the upper, contralateral quadrant (M±s.d.=up 25°±19.97, contralateral 39°±11.73). Spatial response areas measured at either 3 or 5 dB above the minimum threshold decreased with stimulus frequency (3-dB area: r=0.53, p=0.0118, and 5-dB area: r=0.44, p=0.0338). Spatial response areas associated with higher BFs were more concentric and smaller than those of lower BFs, which were larger and often expanded irregularly beyond the tested angles of the frontal auditory field. The results reflect the directionality of the sound-pressure transformation at the pinna of the mouse as demonstrated in our recent study (Chen etal., in press).
Correlations between auditory-filter shape parameters measured at proximal center frequencies
Authors: Fagelson Marc A. , Champlin Craig A.
Published: October 2005

Auditory-filter shape parameters in 20 normal-hearing listeners were determined at center frequencies (CFs) of 913, 1095, 3651, and 4382 Hz using the five-point roex (p,r) method. Slopes of the filters’ skirts were correlated for the CFs in each frequency region at both low and high stimulus levels. In the λ=1000-Hz region, the auditory filters’ low-frequency slopes were significantly correlated at the low and high stimulus levels, while the high-frequency slopes were associated at the high, but not the low level. In the λ=4000-Hz region the relationships were clearer as the low-frequency and high-frequency filter skirts diverged at the low level, but were significantly correlated at high stimulus levels. Level dependencies in auditory-filter shapes indicated subtle differences in cochlear frequency analysis at proximal places along the basilar membrane diminished as signal level was increased. Conversely, in those situations most likely to be affected by active processing along the partition, such as the low-level and high-frequency conditions, auditory filters centered at neighboring frequencies often did not resemble one another. This suggests that active cochlear mechanisms are not uniformly distributed throughout the length of the basilar membrane. [Work supported by the College of Communication (Jamail Grant) and NIDCD.]
Parameter estimation for fuzzy structures. A result concerning vibrations in the low-frequency range
Authors: Soize Christian
Published: October 2005

In the field of structural vibrations, the structural complexity can be induced by ‘‘secondary’’ mechanical subsystems attached to the ‘‘master’’ structure or by ‘‘local eigenmodes’’ of some continuum elastic subelements of the master structure; these local eigenmodes induce a structural complexity when the model of these subelements can only restitute the elastostatic behavior but not its elastodynamic response. Within this context, a model is presented of the apparent vibration damping of the master structure due to the vibrations of the structural complexity. This vibration-damping model is deduced from the theory of fuzzy structures that was previously developed by the author. Presently, this model uses only the mean part of the probabilistic fuzzy law of the fuzzy substructure. A model of the generalized damping matrix deduced from the model of the structural complexity, is explicitly constructed. This generalized damping matrix depends on parameters related to the fuzzy substructure. Problems related to the model parameters estimation are studied. Finally, an example is presented and allows the theory to be validated.
Fuzzy elements, their coupling rules, and the Jaynes–Shannon maximum entropy principle
Authors: Pierce Allan D.
Published: October 2005

Emerging theories of fuzzy structures are regarded as the wholesale replacement of certain portions of the structure by fuzzyelements, whose chief characteristic is a smeared-out (fuzzied) distribution of natural frequencies, so that there are an infinite number of natural frequencies in any given frequency band. Descriptors of fuzzy elements are the mass per unit natural frequency band and the elements of a mass matrix per unit natural frequency band. Modeling of complex structures is simplified by regarding internal and appended structures as assemblages of coupled fuzzy elements, so circuitlaws are here suggested for determining parameters of an overall fuzzy element from the known features of its fuzzy components. In regard to assigning mass distributions among frequencies to actual elements that are to be modeled as fuzzy elements, the appropriate guide is Jaynes’s (1957) general method of statistical inference (principleofmaximumentropy) extracted from Shannon’s information theory. The mass distribution is regarded as a probability distribution, and the known features, such as total mass, asymptotic behavior, mass-weighted average natural frequency, d-c behavior, are imposed as constraints on a variational principle that maximizes the entropy asssociated with that probability distribution, to find the most likely such distribution consistent with the known information. [Work supported by Office of Naval Research.]
Real and apparent dissipation of vibrations of structural systems
Authors: McCoy J. J.
Published: October 2005

Discussions of ‘‘real’’ and ‘‘apparent’’ dissipation of the vibrations of structural elements to which are attached substuctures, have suffered from a lack of precision in terminology. Identifying a real dissipation with the transformation of mechanical energy to heat and an apparent dissipation with the transformation of mechanical energy from a form that one observes to a form that one doesn’t, would clarify issues. A further classification of a real dissipation as either ‘‘resonant’’ or ‘‘nonresonant’’ is suggested. A resonant dissipation is obtained for vibration frequencies that are nearly coincident with the natural frequencies of a subset of the attached subsystems. Finally, a further classification of an apparent dissipation as either ‘‘reversible’’ or ‘‘irreversible’’ is also suggested. The physics underlying the different type dissipations; their modeling; and, the dependence of measures of dissipation on more fundamental measures of the attached substructures will be discussed.
Determination of modal masses from plots of driving point impedance magnitude versus frequency when modal overlap is present
Authors: Livingston Jacques , Pierce Allan D.
Published: October 2005

Implementation of a piecemeal technique for the modeling of complex structures within the context of the theory of fuzzy structures requires that one have some prior knowledge of the distribution of modal masses for each class of internal appendages that have similar design features and function. For each such category, sample calculations or measurements can yield data that can be gathered into an ensemble and then used in the computational replacement of each appendage within that category by a generic fuzzy element. The present paper is concerned with how such data might be obtained from experimental tests that determine how the magnitude squared of the driving point impedance varies with frequency. For a lightly damped one-degree-of-freedom system, basic vibration theory leads to an expression for the (modal) mass which is proportional to the height of the resonance peak divided by the square root of the magnitude of the second derivative at that peak. However, for a multidegree-of-freedom or continuum structure, a fundamental scheme based on the measurement of heights of peaks and of the second derivatives at such peaks can be frustrated by the occurrence of strong modal overlap. A numerical iteration method that can largely overcome this makes use of a general functional form for the complex impedance and proceeds to gradually ‘‘filter out’’ the contributions from the stronger peaks, so that the weaker peaks can be identified and then also filtered out. [Work supported by Office of Naval Research.]
Loss factor of a beaded structure
Authors: Maidanik G. , Dickey J.
Published: October 2005

It is found that when beads are inserted into the interior of a pipelike structure, the damping of the beaded structure may substantially exceed that of the unbeaded structure. The beads are modeled by a ‘‘beaded fluid’’ characterized by a low density, a low sound speed, and a high loss factor. Statistical energy analysis (SEA) is developed to account for the presence of the beaded fluid within the structure. It is shown that in certain frequency regimes and certain choices of the parameters that characterize the beaded fluid, relative to those that characterize the structure, the loss factor of the beaded structure can be designed to significantly exceed that of the unbeaded structure. The mechanism for the increase lies in that the stored energy in the beaded fluid may, in the ‘‘steady state,’’ be made to substantially exceed that in the structure. The bulk of the stored energy is then decimated by the high damping capability that the beaded fluid enjoys. A selected number of computer experiments are cited to illustrate the potential effectiveness of this damping mechanism and the manner by which the parameters, that define the beads and the structure, control it.
Acoustic correlates of perceived vowels of American English
Authors: Miller James D.
Published: October 2005

Relations between four acoustic paramenters, fundamental frequency (F0) and the center frequencies of the first three formants (F1, F2, and F3), and the perception of vowels are described. Prediction of listeners’ identifications of vowels are best when acoustic trajectories are based on all four parameters. These parameters can be taken separately to form a four-dimensional space or they can be combined to form a three-dimensional space such as Miller’s Auditory Perceptual Space (APS). The time-normalized paths through such spaces correlate best with listener responses. Temporal factors such as durations and speeds along these paths, within limits, are not critical. However, the direction of movement along the path can be crucial. While movement in a forward direction usually evokes the perception of the intended vowel, the opposite movement may sometimes evoke the perception of another vowel. Recent work shows that neural networks, trained with inputs based on F0, F1, F2, and F3, perform very similarly to humans listening to the waveforms of the isolated nuclei. These results will be reviewed and their implications for models of vowel perception will be discussed. [Work supported by NIDCD, AFOSR, and CID.]
Analog experiments of tissue damage generated during ESWL treatments
Authors: Takayama K. , Kodama T. , Kuwahara M. , Ioritani M.
Published: October 2005

Among the possible causes of ESWL tissue damage, the interaction of shock waves with cavitation bubbles is believed to be the most responsible. A series of analog experiments has been carried out for clarifying the mechanism of tissue damage during ESWL. Interactions of shock waves with single air bubbles in water were examined, including the formation of a rebound shock wave and the generation of liquid microjets. The collapse of air bubbles which were attached to gelatin walls and exposed to shock waves was quantitatively observed using double-exposure holographic interferometry and high-speed cinematography. In these analog experiments, shock waves were created via microexplosives: 10-mg silver azide pellets were pasted on the tip of an optical fiber and detonated with the radiation of a pulsed YAG laser beam. Details of the bubble collapse were well resolved. More complex materials analogous to human tissue have been tested and will be presented also.
Applications of the trans-spectral coherence technique
Authors: Vaidya P. G.
Published: October 2005

The trans-spectral coherence technique (TSC) [Vaidya and Anderson, J. Acoust. Soc. Am. 89, 2370–2378 (1991)] has been used to remove noise and distortions from periodic signals. Recent results show that the technique is also well suited to analyzing nonstationary signals, including chaos. For example, TSC can be used to distinguish a chaotic signal from a random one. As opposed to a truly random signal, in chaotic signals nonzero TSCs are required, at least for some combinations. In fact, for the Duffing equation undergoing chaos, nearly perfect trans-spectral coherence was observed for many combinations. In this case, TSC proved to be a very useful diagnostic tool, and it helped develop a deeper insight into the nature of the specific attractor, and the associated invariant group structures. Similar strong coherences have also been observed in speech signals. This sheds further light on the issues of speaker and speech recognition. Further, it is important in many fields (heart arrythmia, for example), to be able to predict in advance that a periodic system is likely to become chaotic. TSC can be used to arrive at a premonition of such a forthcoming change.
Hot topics in physiological acoustics
Authors: Nielsen Donald W.
Published: October 2005

For those in the Society whose main interest lies in other acoustic fields, the presentation will review current topics in physiology of audition. Much basic physiological research has been focused on the micromechanics of the cochlea, the end organ of hearing. For many years the cochlear tuning process was through to be passive and mechanical; however, recent studies indicate that active motion of one group of cochlear hair cells adds to and sharpens the tuning. The results and implications of studies of outer hair cell motion will be discussed. Also discussed will be the cochlear implant, a device that addresses injury or loss of cochlear hair cells, the cause of most incurable forms of deafness. With this device, the electric fields of electrodes surgically implanted in the cochlea stimulate the nerve supply in the absence of normal hair cells. Also presented will be recent advances in molecular biology that attempt to induce growth or regrowth of hair cells in cochleae that have none.
Hot topics in physical acoustics
Authors: Atchley Anthony A.
Published: October 2005

The field of physical acoustics involves: (1) the use of our understanding of the parameters governing propagation of acoustic waves in and interaction of acoustic waves with other systems to understand the structure and behavior of those systems; (2) the study of nonlinear acoustic propagation and phenomena; and (3) the use of acoustics to generate or stimulate physical processes. This hot topics presentation will draw on examples from each of these categories to demonstrate both the breadth of the field and how physical acoustics is closely tied to many other technical areas within the Society. Some specific topics are sonoluminescence, thermoacoustics, high intensity ultrasonic surgery, sonic booms, imaging at the nanometer scale, resonant ultrasound spectroscopy, and applications of modulated radiation pressure to fluid mechanics.
Voice analysis: A stochastic approach
Authors: Qi Yingyong
Published: October 2005

Current methods of computing noise present in human voices depend upon being able to determine fundamental periods. In this paper, a method of estimating noise present in human voices that does not depend on the determination of the boundaries between fundamental periods is described. In this method, noise was computed as the uncorrelated component in the voice signal. The magnitude of the uncorrelated component was obtained by computing the average, maximum cross correlation between many pairs of short frames of voice signals. The method is evaluated using synthetic and natural voice signals. Results indicate that it is an effective tool for estimating the noise component in voice signals. [Work supported by NIH.]
High-frequency propagation in a bubbly medium
Authors: Goodman Ralph R. , Caruthers Jerald W. , Stanic Stephen J. , Su Ming Y.
Published: October 2005

During a shallow-water, direct-path experiment off the Panama City, Florida coast a storm passed through the area that gave rise to both a change in sound speed of about 50 m/s and pulse-to-pulse variations that were significantly larger than those found during relatively benign periods before and after the storm. The depth of the water was about 10 m with the propagation path over a range of about 60 m at mid-depth. Very narrow beam pulsed signals from 20 to 135 kHz were transmitted at 1-s intervals. Measurements of the void fraction of bubbles showed a bubble concentration that can account for the change in the speed of sound. Fluctuations in the arrival times can be attributed to small changes in the average bubble concentration along the propagation path. Both scattering and dispersion due to the presence of small bubbles will be discussed. Comparison of measurements before, during, and after the storm period will be presented. [Work supported by NRL and ONR.]