bluuebunny/crossref_metadata_2025 huggingface dataset:
Manifestation of nonlinear elasticity in rock: Convincing evidence over large frequency and strain intervals from laboratory studies
Authors: Johnson Paul A. , Rasolofosaon Patrick N. J.
Published: October 2005

Nonlinear elastic response in rock is established as a robust and representative characteristic of rock rather than a curiosity. This behavior is illustrated from a variety of experiments conducted over many orders of magnitude in strain and frequency. The evidence leads to a pattern of unifying behavior in rock: (1) Nonlinear response in rock is enormous; (2) the response takes place over a large frequency interval (dc–106 Hz at least); (3) the response not only occurs, as is commonly appreciated, at large strains but also at small strains where nonlinear response and the manifestations of this behavior are commonly disregarded. Nonlinear response may manifest itself in a variety of manners, including a nonlinear stress−strain relation (hysteretic/discrete memory), nonlinear dissipation, harmonic generation, and resonant peak shift, all of which are related. The experiments described include: quasistatic stress−strain tests (strains of 10-4–10-1 at frequencies near dc-1Hz); torsional oscillator experiments (strains of 10−4–10−7, frequencies between 0.1 and 100Hz); resonant bar experiments (strains of 10−4–10−8, frequencies between 103 and 104 Hz); and dynamic, propagating wave experiments (strains of 10−6–10−9, frequencies between 103 and 106 Hz). [Work supported by OBES/DOE through the University of California and the Institut Français du Pétrole.]
Hysteresis in elastic behavior: The connection between low-frequency response and acoustic properties of rocks
Authors: McCall Katherine R. , Guyer Robert A. , Zhu Lei
Published: October 2005

The strain response of rock to quasistatic stress cycles (e.g., 10−3 Hz) is highly nonlinear, hysteretic, and displays discrete memory. Rocks also display unusual nonlinear behavior in acoustic wave experiments (e.g., 104 Hz). Nonlinearity and hysteresis are prominent features in elastic measurements on rocks. This observation is the key to making the connection between low-frequency (quasistatic) and high-frequency (acoustic) measurements, e.g., between static modulus and dynamic modulus. A new paradigm has been developed for the description of the elastic behavior of rocks and other consolidated materials. This paradigm uses the statistical properties of an ensemble of micron-scale hysteretic mechanical units to describe the elastic response of a macroscopic piece of material. It provides a recipe for inverting stress-strain data (low-frequency data) for the distribution of hysteretic mechanical units. From this distribution, the high-frequency acoustic response of the macroscopic piece of material can be predicted. The new paradigm will be described in principle and in application. Quasistatic stress-strain data on sandstone lead to predictions for dynamic modulus and resonant response that agree well with experiment.
Experimental determination of the linear and nonlinear dynamic moduli of rock from quasistatic measurements
Authors: Zhu L. , Guyer R. A. , McCall K. R. , Boitnott G. N. , Hilbert L. B. , Plona T. J.
Published: October 2005

The central construct of a new theory of the elastic behavior of consolidated materials is the density in Preisach–Mayergoyz (PM) space. PM space is an abstract space in which the response of the mechanical units in the material to changes in stress state can be tracked. The theory provides a recipe for using quasistatic data to determine ρPM, the density of mechanical units in PM space. This recipe has been applied to quasistatic stress/strain data on three sandstones samples: (a) Berea I, (b) Berea II, and (c) Castlegate. The density of mechanical units ρPM was found for each sample. From ρPM the dynamic behavior of the samples can be predicted. Using the experimentally determined ρPM for each of the three samples the strain response to complicated stress protocols is predicted and the linear and nonlinear dynamic moduli of the samples are found as a function of pressure. The predictions agree well with experiments that test them.
Noise discriminability. II. Leaky integrator models
Authors: Robinson Donald E. , Rickert Martin E.
Published: October 2005

Several two-interval, same–different experiments involving the discriminability of samples of noise have been reported previously. A striking feature of these data is the effect of temporal position: samples that are altered near the end are more discriminable than those in which the change occurs earlier. This effect occurs over a wide range of durations and bandwidths. Here two models are reported that describe these results. In each model the waveforms from the two temporal intervals are jittered in amplitude, filtered, and squared or rectified. In one model, the resulting waveforms are passed through a leaky integrator and subtracted from one another. This difference waveform is squared and passed through a second leaky integrator. A sample of the output of the second-stage leaky integrator taken at the end of the integration period is used as a decision variable from which hit and falsealarm rates are obtained and d′ is computed. In the other model, the squared waveforms are multiplied by an exponential weighting function before subtraction. A signal-to-noise statistic is then used to obtain an estimate of d′. The fitting parameters for each model are the variance of the internal noise process and the time constant of either the second-stage integrator or of the exponential weighting function. The results of simulations will be compared with data from two experiments, and the relation of these models to others involving leaky integrators will be discussed. [Work supported by AFOSR.]
Localization of a virtual acoustic target in the presence of a distractor
Authors: Stellmack M. A. , Macpherson E. A.
Published: October 2005

Localization of a virtual acoustic source in isolation was compared to that for the same source played in the presence of a distractor source. The target stimulus was a tonal complex consisting of a 253-Hz fundamental and all harmonics below 14 kHz. The distractor stimulus was a similar tonal complex with a 353-Hz fundamental. Both target and distractor were 250 ms in duration. Virtual sources were generated by filtering the source stimuli with individualized head-related transfer functions (HRTF’s), and the resulting stimuli were presented over headphones. Listeners were instructed to place an acoustic pointer (wideband noise source) at the same apparent position as the target by pressing buttons on a response terminal to manipulate the pointer position. Listeners were allowed to play the test stimulus and pointer at will during each trial. The variability of the pointer responses was similar in the two conditions (target alone and target-plus-distractor), but the difference between the actual target position and the average pointer position was larger when a distractor was present. Responses in the target-plus-distractor conditions tended to be biased toward the distractor position, particularly when the target and distractor were on the same side of the head.
Breakdown of echo suppression with multiple echoes
Authors: Guzman Sandra J. , Yost William A.
Published: October 2005

If a sound is followed a few milliseconds later by its echo, the echo is often suppressed. If a train of repeating sources and echoes is established and then the source and echo are reversed, there is a temporary breakdown of echo suppression. A procedure has been developed for studying echo suppression in which listeners attend to the last sounds in a series of repeating sounds. Using this procedure the effect of multiple echoes (up to seven) on echo suppression and the breakdown of echo suppression was investigated. In all cases there is a breakdown in echo suppression when the echoes are changed in a number of ways. The results indicate an interaction among number of echoes, spatial location of the echoes, and the timing among the echoes in both echo suppression and its breakdown. The results will be discussed in terms of the concept that echo suppression depends on the listener’s prior experience in the acoustic environment. [Work supported by NIDCD and AFOSR.]
Comparison of peak and energy detection for auditory masking of tones by narrow-band noise
Authors: Goldstein Julius L.
Published: October 2005

Classical energy-detection theory [Green and Swets, SignalDetectionTheoryandPsychophysics (Wiley, New York, 1966)] predicts that masking of tones by Gaussian noise is limited by the variability of detector responses and by internal auditory noise. It elegantly relates detection variability to masker duration–bandwidth product (TW). The theory accounts reasonably for Gaussian maskers with fixed RMS levels, but fails when the level is randomly roved with each stimulus presentation, suggesting that the auditory system detects waveform cues. A solution to this problem is proposed in which energy detection is replaced with the dual cues of envelope peak detection and normalized envelope peak detection, which are optimally processed as in classical theory [Goldstein and Hall, J. Acoust. Soc. Am. 97, 3330(A) (1995)]. The model was studied with periodic noise maskers comprising successive harmonics having uniform amplitudes and random phases, and with Gaussian noise maskers. Fixed-level masked threshold predictions converge to ∼−4 dB SNR for both noises when TW≳4, with small differences otherwise. Roved-level predictions for the periodic noise masker (one period duration) are ∼5 dB higher. Agreement exists between model predictions and the systematic masking data of Richards [J. Acoust. Soc. Am. 91, 3424–3435 (1992)].
Durational effects on masked thresholds in noise as a function of signal frequency, bandwidth, and type
Authors: Hant Jim J. , Strope Brian P. , Alwan Abeer A.
Published: October 2005

The reported perceptual experiments are aimed at quantifying the relationship between masked thresholds of signals within noise as a function of signal center frequency, duration, and signal type (pure tones or 1–8 critical-band noises). Tests are adaptive 2AFC with the signals’ center frequencies ranging between 0.4 and 6 kHz and their durations, between 10 and 300 ms. The masker is flat noise with a spectrum level of 36 dB SPL/Hz sampled at 16 kHz. Four subjects participated in the experiments. Critical-band theory accurately predicts the masked thresholds for tones at 300 ms. Tone thresholds increase almost linearly with decreasing logarithmic duration, and these durational effects are more pronounced at low frequencies. Thresholds for 1 CB noise and tone signals are similar at short durations (10–30 ms). For longer durations and for wideband noises, however, differences both in thresholds and the way the thresholds change with duration are observed. Possible explanations in terms of changing auditory filter bandwidths, temporal integration, temporal onset detection and/or an interplay between these factors will be presented. The data are used to predict the masked thresholds of stop bursts in the presence of noise. [Work supported by NIH.]
Wiener–Hopf techniques in electromagnetics
Authors: Felsen Leopold B.
Published: October 2005

Wiener–Hopf techniques have been applied to a variety of electromagnetic boundary value problems for the past four decades. Examples are presented, together with the techniques used to tackle them. Some questions are then asked concerning the role of Wiener–Hopf model solutions with respect to realistic problem scenarios in electromagnetics or acoustics.
Scattering by objects at fluid/solid interfaces
Authors: Craster R. V.
Published: October 2005

Canonical diffraction and scattering problems involving fluid/elastic solid interfaces are solved exactly using the Wiener–Hopf technique; the farfield directivities are explicitly identified. When fluid loading is light, there are regions of nonuniform behavior and intense beam formation that occur. In addition, an heuristic method is devised that partly decouples the fluid and solid responses. This leads to accurate results in the light fluid loading limit and allows one to utilize some results directly from elastodynamic problems solved when the fluid is absent.
Calculation of diffraction coefficients for a crack in an anisotropic solid
Authors: Wickham Gerry R. , Lewis Patricia A.
Published: October 2005

The diffraction of sound by a semi-infinite planar crack arbitrarily oriented in a homogeneous anisotropic linearly elastic solid is considered. The problem is formulated exactly as an integrodifferential equation with a difference kernel which is the stress tensor corresponding to the fundamental point force solution for the uncracked solid. The solution of this equation is the crack opening displacement (COD) induced by the incident field and this may be expressed in terms of the Wiener–Hopf factors of the Fourier symbol of the kernel. The quantity of physical interest is the diffraction coefficient which is proportional to the Fourier transform of the COD and relates the vector amplitude on an incident ray to the crack edge, to the amplitudes on the diffracted rays. In the general case, the necessary Wiener–Hopf factorization cannot be found explicitly. However, by exploiting the fact that the diffraction coefficient is independent of frequency, it is possible to develop a novel numerical scheme for its evaluation. The exact diffracted field is then analytically expressed in terms of these coefficients. It is shown how the rich qualitative geometrical structure of the diffracted field may be obtained and how the solution reproduces known results for special material symmetries.
Acoustic interaction with wedge-shaped structures
Authors: Norris Andrew N.
Published: October 2005

This paper will review recent developments in solving canonical structural acoustics problems involving wedgelike structures composed of plates and membranes. The two cases considered are (i) a membrane held taut over a line constraint, and (ii) two semi-infinite thin plates welded together to form a wedge. The wedge-shaped structures are subject to unilateral fluid loading from an acoustic fluid. The method of Malyuzhinets, which was used in the 1950s for the purpose of dealing with simple impedance-type boundary conditions on the wedge faces, has recently been significantly developed by A.V. Osipov, who has shown how it can be successfully applied to these structural acoustics problems. The central idea of the Malyuzhinets/Osipov method is to express the acoustic pressure using a generalized Sommerfeld integral, similar to a Laplace transform. The main analytical steps in the solution will be discussed, and some numerical results will be presented. The plate structure is particularly interesting because both subsonic flexural and nonleaky supersonic structural waves are excited at the vertex by an incident acoustic wave. Interesting asymptotics emerge when the wedge angle described by the fluid is almost 180o or 360o. [Work supported by ONR.]
Reflection and transmission of structural waves at a corner of an arbitrary angle
Authors: Lawrie Jane B. , Abrahams I. David
Published: October 2005

This talk is concerned with an analytic investigation into the reflection, transmission, and scattering of fluid-coupled structural waves by a corner of an arbitrary angle. The fluid domain is an open wedge, the surfaces of which are described by high-order boundary conditions (that is, containing derivatives with respect to variables both normal and tangential to the boundary). Malyuzhinets (1958) obtained an exact solution for a wedge with impedance faces. However, until the works of Osipov (1994) and Abrahams and Lawrie (1995), little progress was made on adapting his method to problems with more realistic wave-bearing boundaries. The model comprises a compressible fluid wedge bounded by two plane elastic surfaces. An unattenuated surface wave, incident from infinity along one wedge face, is scattered at the apex. Several different edge conditions are discussed, including configurations which excite in-plane plate motions. Explicit application of these constraints allows the boundary value problem to be formulated as two inhomogeneous coupled difference equations which are solved using Malyuzhinets’ special functions. An analytical solution is obtained for an arbitrary wedge angle.
Young infants’ use of prosodic cues to assess lexical information
Authors: Lacerda Francisco P.
Published: October 2005

Young infants were tested by the high-amplitude sucking (HAS) technique to assess their ability to use prosodic information to pick up word contrasts occurring in sentences. The results presented here were obtained from 33 experiments in which 20 Swedish infants (8 girls and 12 boys) participated. The ages at the date of the experiments varied between 58 and 147 days (mean age 105 days, median 108 days). The infants listened to pairs of natural carrier sentences, produced as child-directed speech, in which target words had been inserted. The infants were randomly assigned to each of the four conditions: (1) contrasting target words in focal position, (2) contrasting target words in nonfocal position, (3) contrast only in the position of the sentence focus, and (4) control condition (no change). The results seem to suggest that the infants, while sensitive to displacement of the sentence focus [F(1,29)=4.518,p<0.042], are unable to attend to the word contrast when the target word is in emphatic position [F(1,29)=2.358,p<0.135], but perform well when the same target word contrasts are presented in nonfocal position [F(1,29)=8.143,p<0.008]. [Research supported by The Bank of Sweden Tercentenary Foundation, Grant 94-0435.]
The relationship between prosody and syntax in generation and comprehension of spoken messages
Authors: Fujisaki Hiroya , Ohno Sumio
Published: October 2005

While it is generally believed that prosody of a spoken message conveys information concerning its syntactic structure, there exist many cases where prosody and syntax are discordant. The discordance, however, does not usually cause any difficulty in comprehension. The present study aims at elucidating the process whereby the prosodic structure is determined in speech production, as well as the process whereby it is utilized in speech perception. Using the contour of the voice fundamental frequency as an index, this paper shows examples of such discordance in utterances of various languages including English, Japanese, and Chinese, and presents an interpretation for the origin of the discordance, based on a model of the cognitive processes involved in message generation and speech production. The role of such discordance in speech preception and message comprehension is also discussed, referring to the cognitive processes involved. Finally, the implication of these results for speech synthesis by rule and automatic speech understanding is also mentioned.
On the acoustics of broad and narrow focus
Authors: Hoskins Steven R.
Published: October 2005

Linguistic analyses of focus [Halliday (1967), Chomsky (1971), Ladd (1980), Selkirk (1984), Gussenhoven (1984)] state that under certain conditions, foci of different scope have identical prosodic realizations. These claims have not yet been supported by empirical data. Eady etal. [Lang. Speech 29(3), 233–251 (1986)] found durational differences between broad and narrow focus within the verb phrase (VP). However, these experiments did not control for syntactic structure: According to Selkirk (1984), only verb-argument VPs have identical broad/narrow focus realization; verb-adjunct VPs do not. This study directly investigates the interaction of focus with verbal arguments and adjuncts. An experiment was conducted where matched sentences with verb-argument and verb-adjunct structures were read under three focus conditions: broad (on VP), narrow (on verb), narrow (on postverbal argument/adjunct). Both speech and electroglottographic data were gathered. Durations, absolute pitch, and change in pitch on the stressed syllable of the verb were analyzed. Preliminary results (three subjects) support Selkirk (1984): In the verb-adjunct structures, focus on the VP and narrow (postverbal) focus are significantly different for duration and pitch change; verb-argument structures, however, are not significantly different for these conditions.
Measurements and interpretation of spatial coherence and angular spread resulting from multiple boundary interactions in a shallow-water channel
Authors: Dahl Peter H. , Fox Warren L. J.
Published: October 2005

Measurements of the spatial coherence of high-frequency [0(10 kHz)] sound having propagated in a shallow-water channel are discussed. The experiment was conducted near Key West, Florida, in water depth of approximately 25 m. The bottom consisted of calcium shell deposits and soft mud. Measurements were made using omnidirectional sources suspended from a spar buoy and a horizontal line array of receivers. Broadband pulses were used in order to resolve the separate arrivals, e.g., direct path, single-surface, and double-surface bounce paths. With each boundary interaction, either surface or bottom, the forward propagating energy is scattered further in angle. The transmissions were measured along a line array oriented transverse to the direction of propagation, thereby giving an estimate of the horizontal coherence or equivalent horizontal angular spread. The results are discussed in the context of key geometric parameters such as source/receiver depth and range, and environmental parameters such as wind speed and surface wave spectral characteristics. [Work supported by ONR.]
Shallow water measurements of time spreading at high frequency
Authors: Hines Paul C. , Collier Arthur J. , Theriault James A.
Published: October 2005

Time spreading measurements provide an indirect measure of the acoustic bandwidth that can be supported by the water channel, which is critical to the design of sonar systems. Time spreading measurements were collected in a water channel 100 m deep, off the coast of Nova Scotia. Data were collected at frequencies of 20–22 kHz, 27–29 kHz, and 35–37 kHz using linear FM pulses 2 s in duration. The experiments were part of a collaborative trial conducted by Canada, the US, and the UK. Canada’s Seahorse array, an anchored, high-frequency active sonar was employed for the source-receiver, and a UK free drifting echo repeater was employed for the target. Source-receiver and target position were recorded using a portable target range operated by the US. In the paper, time spreading measurements are compared with estimates obtained from the generic sonar model (GSM) for the experiment geometry. The GSM estimates of time spreading due to multipath propagtion compare favorably with the experimental data. However, time spreading of individual paths beyond that predicted by GSM is also evident.
A coupled bispectral, temporal and spatial coherence function of the pressure field, scattered from a moving sea surface
Authors: Bjerrum-Niese Christian , Bjo/rno/ Leif
Published: October 2005

Fluctuations in the scattering of high-frequency sound from the moving sea surface is of significance, particularly in underwater acoustic communication systems using adaptive methods. Surface scattering may statistically be described using coherence functions, especially for higher frequencies when the coherent part of the pressure field is virtually nonexistent. Previous studies have presented coherence functions as a function of either spatial and temporal variations of the channel, but with a fixed signal carrier frequency or two signal frequencies and temporal channel variations (or some of the several possible Fourier transform duals). Here, a coupled bispectral, temporal and spatial coherence function is presented. The coherence function is derived from the pressure field, given by the two-dimensional Kirchhoff–Helmholtz integral for two monochromatic tones evaluated at separate receiver positions. The channel variations are caused by a wind-driven, gravity-wave dispersed sea surface with a Pierson–Moskowitz spectrum. The derivation of the coherence function involves numerical integration. Numerical results are compared to earlier model data from the literature. [Work sponsored by the Danish Technical Research Council.]
Real time signal processing for high-frequency long distance crosswell tomography
Authors: Kuru Murat , Yamamoto Tokuo
Published: October 2005

Acoustic crosswell tomography was used for determining the sediment porosity, permeability, and shear strength from travel-time measurements by means of travel-time inversion and rock mechanics [Yamamoto etal., Geophysics (1994) (1995)]. These properties can be used to model the propagation and scattering of acoustic waves in saturated sediments. Due to the effects of intrinsic attenuation, transmission loss, and scattering, crosswell measurements usually are limited to ranges of 50–100 times the wavelength of the signals. It was believed that the diffusive nature of scattering put the coherent limit of acoustic wave propagation in sediments at approximately 1000 wavelengths. To extend the measurements of the propagation of acoustic waves to longer ranges, a real time processing and data acquisition system was employed. A crosswell tomography experiment with a crosswell distance of 540 m was performed at a limestone aquifer at Sanibel Island, Florida. Pseudorandom binary sequences modulated with carrier frequencies up to 6 kHz, which puts the range around 1400 wavelengths, were successfully transmitted by using pulse compression and coherent averaging techniques. The hydraulic structure of the Earth with a cross section of 540 m×150 m has been imaged at spatial resolution of a few meters. [Work supported by ONR.]
Broadband frequency dispersion in shallow water as an active classification technique
Authors: Wilson James H. , Davies J. Huw , Bourke Robert H.
Published: October 2005

Recently, an active broadband dispersion phenomenon was observed empirically in measured data for propagation paths within the mixed layer (ML) [Dien etal. (1994)]. This so-called Wilson Dispersion Phenomena (WDP) is explained simply by noting that high-frequency energy trapped within the ML travels faster than low frequencies that diffractively ‘‘leak’’ out of the ML. Thus WDP is a useful technique for distinguishing between reflectors in the ML and reflectors below the ML. More recently it was shown that the WDP may occur in other shallow-water environments [Davies etal. (1994)]. Several sound-speed profile (SSP) environments are examined, using normal mode theory, for depth dependence of broadband frequency dispersion. A very conservative approach is taken regarding frequency reflectors. Geoacoustic properties of the bottom are not addressed. SSPs for which dispersion depth dependence is observed within the water column for a lossy bottom are labeled useful for active classification. Future research including geoacoustic properties of the sub-bottom may lead to a wider range of SSP and geoacoustic sub-bottom environments which produce dispersion depth dependence. It has been empirically observed that bottom reflectors (the primary false targets) never have significant dispersion and are spread over much longer times than reflectors within the water column. a)Work performed while on temporary leave from Neptune Sciences, Inc., Slidell, LA 70458; b)Currently stationed at Fleet Numerical Oceanographic Ctr., Monterey, CA 93943.
Broadband frequency dispersion prediction using shallow-water data from Tanner Bank
Authors: Fabre J. Paquin , Wilson James H.
Published: October 2005

Recent analyses of explosive charge reverberation and echo data [Davies etal. (1994)] showed a useful active broadband dispersion phenomena that was observed empirically in measured data for propagation paths within a mixed layer (ML). This Wilson Dispersion Phenomena (WDP) was originally noted in an environment which was characterized by a mixed layer. In April, 1994 an experiment [Holland etal. (1994)] was conducted under Navy sponsorship off the coast of California (Tanner Bank) in order to examine low-frequency active acoustic sources for use in characterizing bottom parameters in shallow water. This data set provided an ideal scenario for further examination of WDP. Upon preliminary examination of the Tanner Bank data set, the WDP was found to not only exist, but also to be predominant in environmental scenarios other than in the presence of a mixed layer. The phenomena proves to be highly dependent upon source–receiver geometry and environmental acoustic (EVA) characteristics such as sound-speed structure, bathymetry, bottom sediments, etc. It has been shown using the Tanner Bank data set that the occurrence of this phenomena can be modeled to a reasonable degree of accuracy using a time domain finite element parabolic equation model and a normal mode model. [Work supported by ONR.]
Innovation in acoustical design
Authors: Marshall A. H.
Published: October 2005

Research clearly has a relationship to the design of concert halls, as does innovation. How do these merge in the owner’s and user’s best interests? In some cases the research precedes the design. In others the design itself becomes a research hypothesis for exploration, sometimes over many years. The noise in the system is political power. Aspects of the design process for several innovative halls will be discussed, together with the research background, predictive techniques applicable to each, and a summary of results achieved.
New results for the music critic listening experiment at Dallas’ Meyerson Symphony Center
Authors: Lubman David , Siebein Gary W.
Published: October 2005

A pilot experiment was conducted to compare the assessments of the acoustics of a concert hall made by music critics, musicians, and ‘‘others.’’ The experiment, a cooperative effort between the ASA and the Music Critics Association of North America (MCANA), was performed in Dallas, TX at the McDermott concert hall of the Meyerson Symphony Center during MCANA’s June 1994 meeting. The critics’ meeting provided a unique opportunity to obtain acoustical assessments from a statistically significant number of critics attending concerts in the same hall. Standard survey forms and instructions were placed in the registration packets of about 75 music critics at check-in, and about 1000 noncritic volunteers attending concerts on two consecutive nights. The initial, disappointingly small number of survey forms returned by the critics was augmented by the critics’ responses to a supplemental mailed appeal. Ultimately, 18 critics, nine musicians, and 20 ‘‘others’’ submitted survey forms for the Dallas Symphony concert. thirteen critics, 36 musicians, and 106 ‘‘others’’ submitted survey forms for the Houston Symphony concert held on the next night. With these new responses, statistically interesting, significant results can now be reported. [Work supported with private donor and TCAA Technical Initiative funds.]
New developments of the ‘‘sound particle’’ concept in room acoustics
Authors: Stanzial Domenico , Prodi Nicola
Published: October 2005

The concept of a soundparticle, which is a small amount of acoustic energy that is supposed to move inside the sound field, has been used for a long time in room acoustics, principally in connection with the statistical interpretation of the reverberation theory and more recently with the ray-tracing-based computer simulations. New research on energetic properties of acoustic fields [G. Schiffrer and D. Stanzial, ‘‘Energetic Properties of Acoustic Fields,’’ J. Acoust. Soc. Am. 96, 3645–3653 (1994)] leads to the possibility of rigorously defining, by means of the energytransfervelocity, the trajectories of sound particles. Furthermore, the general decomposition of the air-particle velocity v into one part vp, which has the same time dependence as the acoustic pressure p, and the other one vq=v−vp such that 〈pvq〉=0, allows one to define two separate kinds of sound particle trajectories. These different behaviors are connected, respectively, to the instantaneous active and reactive acoustic intensities. A brief summary of the theoretical framework and some visualizations of sound particle trajectories for simple model fields will be presented.
Using broadband measurements and modeling near swimbladder resonance frequencies to determine biological characteristics of fish populations
Authors: Love Richard H. , Thompson Charles H.
Published: October 2005

The Naval Research Laboratory (NRL) has been investigating low- to mid-frequency scattering from dispersed layers of fish for a number of years. Since 1988, NRL has conducted eleven experiments in a variety of regions, over shelf, slope, and deep waters. Scattering measurements have been made on many different fishes, from large commercially important fish, such as salmon, to small mesopelagic fishes that comprise the deep scattering layer. The frequency range of interest in these measurements, approximately 0.5 to 10 kHz, is the frequency range in which the swimbladders of many fish resonate. By employing a swimbladder scattering model in conjunction with the scattering data, information of the biological characteristics of the scatterers can be derived. This technique can provide information on the geographical distribution, depth, size, abundance, and swimbladder characteristics of the scatterers. The technique has been used successfully to provide detailed information on well-known species as well as to identify significant populations of fish in habitats where they were not expected. Examples of results for both well-known and unknown fish from both deep and shallow water are presented.
Determination of fish school structure from low-frequency backscattering
Authors: Nero Redwood W. , Feuillade Christopher
Published: October 2005

A scattering model for predicting the backscattering from small ensembles of fish is used to determine the size and spatial arrangement of fish in schools. The model was initially developed to predict the low-frequency spectral signature of a fish school based on information on fish size and spacing. The inverse problem is to determine the size and spatial arrangement of fish within schools from measured scattering spectra. The method is applied to simulated data and measurements. Simulations provide information on the range of parameters that can be included in the inverse solution. Measurements are from several sources. They include examples of published data and recent measurements made by the Naval Research Laboratory. Results of this study suggest that low-frequency backscattering from fish schools may contain enough information to aid in their acoustic classification.
Sensitivity of the inverse problem to size-class selection
Authors: Jech J. Michael , Horne John K. , Schael Denise M.
Published: October 2005

Fisheries sonar systems typically operate at discrete frequencies between 38 and 420 kHz. Can length-frequency distributions of aggregated fish be accurately estimated using available frequencies and the inverse problem? The inverse problem requires measured fish lengths and realistic scattering models. The size distribution of threadfin shad (Dorosomapetenense) in Lake Nornman was estimated using 120-, 200-, and 420-kHz data, and a recently developed scattering model [Jech etal., J. Acoust. Soc. Am. (in press 1995)]. Size distribution estimates were compared to length frequency measurements from purse seine catches. Fits of probability density functions (PDF’s) using the inversion technique to those using length frequency measures were sensitive to the choice of fish size classes. Preliminary results indicate that estimation of length frequencies using multi- frequency data and the inverse problem appears dependent on the shape of measured length-frequency distributions. [Work supported by NOAA Coastal Ocean Program (NA16RGO 492-01) and NSF (OCE-9115740).]
High-power electromagnetic transducer array for Project Artemis
Authors: Massa Donald P.
Published: October 2005

The low-frequency, high-power transducer array installed on the Mission Capistrano for use in Project Artemis was developed by Massa during the late 1950s and manufactured during 1961. The 33-×50-ft array contained 1440 Massa model TR-11C transducer elements. This paper will present a historical review of this 300 000-lb megawatt transducer array that successfully operated in the 420-Hz region. The design of the transducer will be described, along with a few of the manufacturing procedures used to hold the resonance of the 180-lb vibrating structure to within 10 Hz. The 10-mile-long receiving array, consisting of 200 towers 80 ft tall containing hydrophones and lag lines for beam steering, will also be discussed.
Historic overview of the concept of velocity control relative to acoustic interactions in sonar arrays
Authors: Carson David L.
Published: October 2005

This paper discusses the following historic points concerning the concept of velocity control for sonar projector arrays which have strong acoustic interactions among the transducer elements of a given array. (1) Diagnosis of problems that led to the introduction of the concept of velocity control and of including velocity control provisions in the design of the subject sonar projector arrays. (2) Some early observations concerning potential methods to provide velocity control and the corresponding early state of the art for a practical hardware realization of each of these potential methods. (3) An array design approach which specifically included velocity control provisions. (4) A general definition of velocity control in the context of the array design approach of item (3) above. (5) The first specific velocity control method used in the application of the concept of velocity control to the LORAD ARRAY. (6) Two more recent examples of implementation of specific velocity control methods applied to actual high-power, low-frequency, highly interactive projector arrays. (7) An example of the usefulness of inclusion of velocity control considerations in one’s thinking concerning active sonar system design when interactive projector arrays are under consideration. (8) A parting thought—the discussion for the above seven points was in the context of analysis in the steady-state frequency domain; what possible relevance might these experiences have to present design problems concerned more with non-steady-state time domain analysis?
Approximating array mutual interactions
Authors: Benthien George W.
Published: October 2005

In this paper some of the analytic and numerical techniques that have been applied to the array interaction problem will be reviewed. For problems where high accuracy is not required, many modelers have used an approximation for the mutual interactions that has come to be known as the Pritchard approximation. In this paper a new approximation technique will be presented which appears to be more accurate than the Pritchard approximation for the cases that have been examined. Results will be shown that compare this new approximation scheme both with the Pritchard approximation and with more accurate numerical computations. [Work supported by SPAWAR PMW-182.]
An overview of variational methods
Authors: Robinson Harold C.
Published: October 2005

Variational methods provide a powerful method for determining the behavior of complex physical systems without needing to solve the equations of state or satisfy the boundary conditions exactly. This technique has been widely applied in the areas of structural vibration and scattering, but has not been used much in the areas of transduction and array modeling. The advantage of this method over many others is that the answers obtained from variational principles are always significantly better than the inputs to them. A totally general method for deriving stationary variational principles from the equations of state and the boundary/initial conditions will be shown. Techiniques for choosing the inputs, or trial functions, judiciously will be discussed. The method will be illustrated using two examples: Determining the resonance frequencies of a clamped vibrating string and of a string with an attached point mass. The results of the variational treatment will be compared with exact analytical solutions of the problem for both accuracy and simplicity of solution. A brief historical overview of variational methods in acoustics will also be given.
Calculation of the total and individual powers of vibrating finite panel by mutual radiation impedance
Authors: Mikami Daiji , Hasegawa Akio , Kikuchi Toshiaki
Published: October 2005

Recently the active acoustic control technique using the controllable secondary source has attracted much attention as an effective method to reduce the power output from the primary source. In this technique, essential reduction in the sound power output from the primary source is achieved by the acoustic destructive interaction effect which is characterized by mutual radiation impedance. In this paper, the mutual radiation resistance of two identical rectangular panel cells (a×b) simply supported in an infinite baffle is determined from the total power output radiated to the farfield. Numerical values of the mutual radiation resistance are given as a function of ka for rectangular panel cells with various aspect ratios and orientation angles. The 3-D representations of individual output power from a multiplicity of panel cells are shown for (a) even–even mode (quadrupole type), (b) even–odd mode (dipole type), and (c) odd–odd mode (monopole type). In some 3-D plots of odd–odd modes, for frequencies well below the critical frequency, the magnitude of the power output from each panel cell is observed to follow the velocity distribution of panel cells exactly.
Computation of complex wave numbers and amplitudes on vibrating structures from response data
Authors: McDaniel J. Gregory , LePage Kevin D. , Martin Nathan C.
Published: October 2005

This work demonstrates a robust approach for computing complex wave numbers and amplitudes of waves in structures from experimental or numerical data. The approach postulates a wave field, which is a linear combination of damped waves. The number of waves and initial estimates of the complex wave numbers are based on any apriori physical knowledge and on the results of standard analyses of the data, such as wave-number transforms and spatial attenuation rates. Given these initial estimates of wave numbers, associated wave amplitudes are computed by linear least-squares inversion to data. Optimization algorithms improve these estimates by searching for complex wave numbers and amplitudes that minimize the normalized mean-square error between the data and the wave field. This approach is often more robust than Prony-based techniques, which require equally spaced data and are more sensitive to noise or unmodeled components. The approach is demonstrated on experimental vibration measurements of a damped box beam. Loss factors are computed for traditional flexural waves as well as plate waves, which involve flexural motions of the walls of the box beam. [Work supported by ONR.]
Energy transport in a vibrating, extruding/intruding cantilever beam
Authors: Konzelman Charles J. , Stylianou Marinos C.
Published: October 2005

Everyone has performed this experiment at one time or another: Take a ruler, hold it over the edge of a tabletop like a cantilever beam, pluck the end, and slowly retract the ruler into the tabletop. The frequency of the resulting vibration is observed to increase as the ruler is retracted into the tabletop. Although numerical simulations based on the linearized equation of motion for this intruding cantilever beam reveal that its total energy increases with the passage of time, the source of the energy is apparently unaccounted for. This study examines the transport of energy into (and out of) a cantilever beam which intrudes or extrudes from a rigid support with uniform axial velocity. By examining some second-order effects at the support and over the length of the beam, an attempt is made to define the mechanisms of energy transport into (and out of) the beam. This has potential application to the solution of transverse vibration control problems, if the velocity of axial intrusion/extrusion is a properly prescribed function of time.
Perceiving oral release rate of voiced stop consonants
Authors: Williams David R.
Published: October 2005

Because of the differences in articulator mass and contact length, initial rates of increase in a constriction area at a consonant release may differ for stops produced at the various places of articulation. This paper examines the listener preferences for variations in the oral release rate (ORR) of syllable-initial labial, alveolar, and velar voiced stops. For each place of articulation, a five-member ORR continuum was synthesized using a set of articulatory parameters [K. N. Stevens and C. A. Bickley, J. Phon. 19, 161–174 (1991)] to control the rate of increase in the oral cross-sectional area at the stop release. ORRs were 15, 20, 30, 50, and 100 cm2/s for [b] and [d], and 10, 15, 20, 30, and 50 cm2/s for [g]. The synthesized CV syllables were presented in pairs to naive and experienced listeners for preference judgments. In general, faster ORRs were preferred for labial stops than for alveolar and velar stops. For the most stimuli, experienced listeners showed clearer preferences than did naive listeners. Normalized scores indicated that the range of preferred ORRs for alveolars was narrower than for labials and velars. Implications of these results for studies of phonetic prototypes will be discussed. [Work supported by NIH.]
Acoustic and perceptual study of French stop bursts: Implications for stop recognition
Authors: Djezzar Linda
Published: October 2005

A perceptual and acoustic investigation was conducted to better understand the discrimination power of the burst regarding place-of-articulation of French stops. These perceptual experiments showed that the burst provided very reliable spectral information about stop place and that prior knowledge of the vowel identity led to a slight but significant improvement in stop identification [A. Bonneau etal., to appear in J. Acoust. Soc. Am. (1995)]. This acoustic study confirmed that burst cues cannot be extracted and exploited without taking into account the vocalic context. Based on these conclusions, a hybrid recognizer was implemented. First, it recognizes the vocalic context, and then it takes this into account to extract and exploit the burst cues for the stop recognition task. The vocalic context was correctly recognized in 90% of the cases: Back vowels were perfectly recognized, central vowels with 80% accuracy, rounded front vowels with 90%, and unrounded front vowels with 89%. The global recognition rate of stop place was 88%. Statistical tests indicated that the best recognized stop was /k/ (93%), then /t/ (87%), and /p/ (84%). These results agree with listeners’ performance observed in the perceptual experiments (/k/: 94% ≳ /t/: 91% ≳ /p/: 62%).