bluuebunny/crossref_metadata_2025 huggingface dataset:
Factor analysis of the perception of the evaluation of environmental sounds using adjectives describing sound quality, emotional state, and information carried by sounds
Authors: Sone Toshio , Abe Kôji , Ozawa Kenji , Suzuki Yôiti
Published: July 2002

In order to investigate into the perception of environmental sounds, a psychoacoustic experiment was carried out. The experiment was performed with the SD (semantic differential) method using 66 environmental sounds for 39 pairs of the descriptive adjectives in Japanese. These pairs of descriptive adjectives are roughly divided into three groups. One of them was adjectives describing sound quality that had been used in similar studies reported so far. The other groups were adjectives describing emotional states of evaluators due to the sounds and information carried by sounds in addition to them. The new adjectives were selected for explaining a more general state of perception of the environmental sounds. As the result of a factor analysis, five factors were obtained. Three of them were factors describing ‘‘aesthetic state,’’ ‘‘volume,’’ and ‘‘brightness’’ of sounds. These factors correspond to the three well-known factors describing sound quality. Other than these, two new factors were derived: a factor concerning information on environment and a factor concerning the significance of sound. Moreover, it was shown that emotional states produced by environmental sounds correlate with the factor concerning the aesthetic state.
Wind noise challenge in the automobile industry
Authors: Her Jen-Yuan , Coney William B.
Published: July 2002

Aerodynamically generated noise during vehicle operations is of increased importance for automobiles as operating speeds increase and design improvements reduce noise contributions from the powertrain and road tire interaction. Wind noise reaches the interior through a variety of mechanisms, including the aeroacoustic penetration and aerodynamic excitation of vibration, and its radiation of sound from vehicle greenhouse (roof, windshield, side glasses, and backbite) and underbody. Although vehicle wind noise performance keeps improving, the fundamentals of wind noise generation and transmission paths still remain uncertain. Instead of relying on measurements on hardware, the recent development of the practical CAE approach, which is different from direct CFD plus FEA simulation, may shed light on solving the puzzle from the statistical energy analysis (SEA) point of view. This paper raises issues to be solved in vehicle-shape-related wind noise root-cause understanding and prevention using SEA. Wind noise mechanisms such as vehicle body wall pressure fluctuations (pseudonoise) generation, its scaling law, and interaction with body structure are examined in detail. Challenging issues such as the identification of low wave number contribution versus convective ridges of pseudonoise to structure excitation and how sound is radiated to driver’s and passengers’ ears are discussed.
Context effects in time discrimination
Authors: McAuley J. Devin
Published: July 2002

Music and speech processing exemplify skilled perception of temporal patterns, as both require an ability to make fine-grained comparisons of relative duration. Clock theories of time perception have been used to model the discrimination of isolated durations successfully, by assuming that temporal resolution is determined by the statistical variability of an independent central timing process. However, the explanatory power of the clock model has been shown to be limited when applied to more naturalistic tasks such as the detection of a temporal deviation embedded within a temporal pattern. This paper discusses an entrainment theory of time discrimination that is based on the concept of coupled oscillators. The theory accounts for a number of contextual effects in time discrimination which have been problematic for clock models. The theory also applies equally well to the discrimination of isolated durations. An important link is demonstrated between fast and slow tempos, short and long durations, and early and late onset of a comparison sequence which only becomes clear when one assumes that the relevant psychological variable in time discrimination is relative phase.
Implementation of a broadband, environment-sensitive detector in real-time systems
Authors: Haralabus Georgios
Published: July 2002

Active systems, such as Low-Frequency Active Sonars (LFAS), have extensively used the matched filter method for detection purposes. This model-free technique is designed to maximize the signal-to-noise ratio of known signals irrespective of the nature of the waveguide. However, shallow water and dense multipath conditions often distort and obscure the matched filter output to a point at which reliable detection is not possible. The objective of this project is to investigate the implementation of a Channel Sensitive Processor (CSP) in real time systems. The performance improvement of the conventional matched-filter processor by exploiting characteristics of the medium is demonstrated both in an ambient noise and a reverberation-limited environment. It is clearly shown that environmental mismatch poses the primary problem in applying the CSP in real-time systems. Environmental uncertainty can be overcome by utilizing global search methods in conjunction with the CSP detector. In implementing such a scheme, the balance between potential advantages and concomitant disadvantage of inefficiently long real-time processing is examined.
Parabolic equation models for poroelastic transversely isotropic sediments
Authors: Fredricks Andrew J. , Siegmann William L. , Collins Michael D.
Published: July 2002

Anisotropy in ocean sediments can have a significant effect on transmission loss. A parabolic equation (PE) model for problems involving transversely isotropic elastic sediments was recently developed [A. J. Fredricks et al., J. Acoust. Soc. Am. 101, 3182(A) (1997)]. Biot’s theory of poroelasticity, which is appropriate for some sediments, is a generalization of elasticity that includes effects due to fluid-filled pores. Propagation models have been developed for poroelastic media, but only for the isotropic case. A poroelastic PE model is extended to handle transversely isotropic sediments. A description of the model will be presented along with examples to illustrate the effects of anisotropy. [Work supported by ONR.]
Broadband propagation over randomly varying, range-dependent elastic sediments
Authors: Jaye Michael , Tang Xin , Badiey Mohsen , Siegmann William L.
Published: July 2002

Acoustic experiments conducted over different tracks at the Atlantic Generating Station (AGS) site have shown significant transmission loss variability. These fluctuations cannot be accounted for entirely by bathymetric and water volume variations. Consequently, as suggested by previous studies, geoacoustic variations must be responsible for significant portions of the variability. We can take advantage of the relatively extensive core data that are available at the AGS site to model both the larger-scale range dependence and the smaller-scale variability. Uncertainties in the geoacoustic fields are modeled here by varying the vertical correlation length of the core profiles which changes the coefficients of representations by empirical orthogonal functions. The stochastic field representations are used for propagation modeling with both elastic and fluid sediments. Statistics of broadband signal transmission loss fluctuations are determined in terms of geoacoustic variabilities. Sensitivities of transmission loss predictions to frequency dependence of geoacoustic parameters are examined. Simulation statistics are compared with experimental data. [Work supported by ONR.]
Holographic reconstruction of active sources in a three-dimensional enclosure
Authors: Kim Yang-Hann , Kim Young-Key , Ko Byeongsik , Ko Kangho
Published: July 2002

This study proposes a method to identify active sources. The theory itself does not limit the application of the proposed method, but the main aim has been focused on finding the location of active noise sources and their strengths in an enclosure. The acoustic holography method can be applied to identify active sources, primary sources if one prefers to call them. However, it will depict all sources including imaginary sources, which one may call secondary sources, which are due to reflections on the walls of enclosure. In this study, an attempt has been made to distinguish these two different types of sources. First, boundaries are modeled by the inhomogeneous Robin boundary condition. It makes it possible to represent the boundaries as the combination of general ideal sources and passive boundaries; the ideal sources imply the primary sources, while the passive boundaries control the secondary sources. Second, this general boundary condition is combined with the holography method to reconstruct the strength of ideal sources. A technique for estimating surface admittance of passive boundaries is also proposed for a three-dimensional sound field by generalizing that for a duct.
Superdirectivity design for a sphere-buffled microphone array
Authors: Kawahara Kazuhiko , Fukudome Kimitoshi
Published: July 2002

For the signal extraction from a diffuse sound field, the superdirecitonal microphone array seems to be more stable and more effective than the noise canceling microphone array system. In this research, for the sphere-baffled microphone array (SBM), the superdirectivity characteristic was designed by the frequency domain beamforming method and the complex least mean square algorithm. The frequency domain beamforming is a method for a broadband beamforming. There is a possibility of improvement of the directivity frequency characteristic. The SBM is an array which was embedded 36 elements on the rigid diffractive sphere of 8.84 cm radius. An advantage of SBM is its isotropy. When the directivity characteristic was fixed for a definite direction, only the shift coefficent can be used to change the mainlobe direction. This idea can be easily generalized into the three-dimensional mainlobe control. In a typical design calculation, for the beamwidth of −3 dB, 30° was achieved at the frequency 2 kHz. This characteristic is comparable to that of a larger size microphone, which is called a shotgun microphone.
Maximum likelihood track-before-detect matched-field beamforming with SWELLEX data
Authors: Harmanci Kerem , Tabrikian Joseph , Krolik Jeffrey L.
Published: July 2002

Moving source localization methods are seriously limited at low signal-to-noise ratios because the signal energy becomes spatially spread over long observation times. In this paper, the integration time available to matched-field beamformers is extended by incorporating a priori statistical knowledge of the source dynamics. This is accomplished by first showing that the well-known minimum variance beamformer output power is essentially the log-likelihood function with respect to source location under a model consisting of a single target in an unknown but structured noise field. This likelihood function for a single frame of data may be combined with the conditional distribution of the current target position given its previous location to obtain a maximum-likelihood (ML) track-before-detect processor. In cases where the sample covariance matrix is ill-conditioned, derivation of a constrained ML estimate assuming known diffuse noise level is given. Results are presented using vertical hydrophone array data for an underwater acoustic source off the coast of southern California. Comparisons with conventional MV matched-field beamforming demonstrate that incorporating source dynamics into the processor improves its ability to maintain the target track even in the presence of interference.
The extraction of a target scattering response from measurements made in a range-dependent shallow-water environment
Authors: Sarkissian Angie
Published: July 2002

The free-field scattering response of a target may be extracted from measurements made over long ranges in a range-independent shallow-water environment by the use of vertical array of sources and vertical array of receivers. The procedure requires the generation of a low-order shallow-water mode by the source array and the extraction from the received echo at the receiver array of a low-order shallow-water mode. The algorithm is generalized to range-dependent environments where additional complications exist due to the mode coupling produced by the range dependence in the shallow-water environment, which exists in addition to the mode coupling produced by the scatterer. Results of numerical simulations are presented for a ribbed cylindrical shell with hemispherical end caps. The target scattering response is computed using the finite elements and infinite elements method, and the propagation is computed using the parabolic equations method. [Work supported by ONR.]
Formalism for boundary scattering in waveguides
Authors: Berman David H.
Published: July 2002

A natural scheme for discussing scattering in a waveguide with rough boundaries involves propagating waves from a source to the rough boundaries, followed by some form of interaction with the boundaries, followed by propagating from the boundaries to a receiver. The interaction with the boundaries is often described by a scattering amplitude whose relationship to the scattering amplitude for the same boundary located in a half-space is not entirely clear. The present work shows what this relationship is and what propagator should be used to carry the waves to and from the boundaries. These results are based on a systematic multiple-scattering analysis and provide non ad hoc expressions for both the scattering and the propagation parts of the problem. As an illustration, the problem of computing reverberation time histories is discussed, a problem beyond the realm of parabolic equation methods which are sometimes used to treat multiple scattering.
The detection of cylindrical objects of low acoustic contrast buried in the seabed
Authors: Evans Ruthven C. , Leighton Timothy G.
Published: July 2002

It is anticipated that the next generation of submarine fiber-optic telecommunications cables will be invisible to present-day detection systems. In cooperation with Cable and Wireless (Marine) Ltd., research has been conducted into the remote detection of buried objects of low acoustic contrast, with particular emphasis given to the detection of buried cables. Specifically, this has concerned the design of a detection system that can reliably discriminate a small diameter (cm scale), cylindrical target buried to a depth of up to 1 m below the seabed from a range of 1 m above. A purpose-built, laboratory-scale, automated sensing system comprising a bistatic arrangement of adjustable, focused transducers is described. This apparatus has been used successfully in the high-resolution imaging of a range of buried objects, proving an acoustic detection system to be a feasible solution. Recent experimental investigations have focused on two areas: Waveform optimization techniques, to maximize seabed penetration and target interaction, and matched filtering and clutter reduction techniques, to optimize the detection system to the acoustic signature of a particular buried object. Results are presented.
Representation of complex spectra in the peripheral auditory system
Authors: Young Eric D. , Calhoun Barbara M. , Yu Jane , Nelken Israel
Published: July 2002

The representation of acoustic stimuli in the auditory periphery is tonotopic; frequency is mapped onto a place in the array of auditory neurons and the stimulus energy at each frequency is represented by the activity of neurons at the corresponding place in the neural array. Despite this generality, the details of the process can be complex, in part due to nonlinearities in neural processing. In the dorsal cochlear nucleus (DCN), for example, neurons give the same response to an energy peak in the spectrum as they do to an energy notch. Because of the nonlinearities, it may not be possible to predict the responses to arbitrary spectral shapes from responses to tones. In the DCN, a physiological model which accounts for the nonlinearities has been developed, but this method is not generalizable. A method for characterizing receptive fields for broadband stimuli has been developed based on the presentation of ensembles of stimuli with random spectral shapes; a neuron’s sensitivity to a particular frequency is obtained from the correlation between the neuron’s rate and the stimulus energy at that frequency. Because this method uses complex stimuli, it should better predict responses to complex stimuli of similar bandwidths. [Work supported by NIDCD.]
Sound transmission through permeable double-leaf membranes
Authors: Sakagami Kimihiro , Kiyama Masakazu , Uyama Toru , Morimoto Masayuki
Published: July 2002

Double-leaf membranes with a permeable interior leaf are one of the typical constructions in membrane-structure buildings. A theory to predict the sound-pressure reflected by, and transmitted through, this type of double-leaf membrane was established by taking into account the coupled motion of the membranes and surrounding sound field [K. Sakagami, M. Kiyama, and M. Morimoto, J. Acoust. Soc. Am. 100, 2735(A) (1996)]. In this same paper, the theory was experimentally validated. That work focused on absorption characteristics since the lack of absorption is one of the main acoustical problems in this type of building. The present paper investigates the sound transmission through a structure of this type in order to gain insight into its sound insulation performance which, in many cases, needs to be improved. The effects of the parameters of the double-leaf membrane on its transmissibility are demonstrated and discussed through numerical examples: The characteristics drastically change with the permeability of the interior leaf. The effect of the interior permeable leaf’s mass is slight, whereas that of the exterior impermeable leaf is significant, particularly at mid-high frequencies. The effect of an absorbent layer in the cavity is also examined.
Prediction of noise transmission through commercial profiled metal cladding systems
Authors: Lam Y. W.
Published: July 2002

Lightweight profiled metal cladding systems generally have poor acoustic insulation characteristics, and traditional theories for evaluating noise transmission through building elements are usually not applicable to double-skin profiled systems because of their orthotropic nature. Based on extensive experimental observations, a new method for predicting the sound reduction index (SRI) of commercial double-skin cladding systems is proposed. The method combines existing theory for orthotropic flat plates with finite element analysis to account for the pronounced ‘‘dips‘‘ in the SRI at midfrequencies, which are caused by the resonances of the profile geometry. The predicted SRI was shown to compare well with measurements on 15 cladding systems used in the experimental work. The method was further extended to cover commercial double-skin cladding constructions. Analytical equations were formulated to account for the orthotropic nature of the cladding sheets, the sound bridging through fixing supports, and the sound reduction through the in-fill insulation. Comparisons of predictions against sound reduction measurements were made on a wide range of commercial cladding products. Good agreement between predictions and measurements was found.
Effect of low-frequency seismic exploration signals on the cetaceans of the Gulf of Mexico
Authors: Rankin Shannon , Evans William E.
Published: July 2002

The increasing use of seismic exploration has created a need to understand effects that intense low-frequency sounds have on the distribution, abundance, and behavior of cetaceans. The goal of this study is to determine possible effects of seismic exploration on cetaceans in the northern Gulf of Mexico. Low-frequency sounds originating from seismic exploration were compared with the presence/absence of cetaceans as determined by acoustic and visual methods of detection. The recordings were collected via a towed passive hydrophone array during seasonal GulfCet research cruises from 1992–1997. The study area consisted of 14 north–south transects ranging from the 100–2000 m isobath in the northern Gulf of Mexico. For odontocetes, with the exception of sperm whales, no relationship between presence of low- and medium-frequency seismic noise was found on a relatively large spatial scale of hundreds of kilometers. For mysticetes, results were inconclusive due to small sample size. These findings suggest that the repetitive signals generated by seismic exploration may not have a negative impact on the large-scale distribution or overall abundance of delphinids in the Gulf of Mexico. However, additional studies have indicated possible negative impacts on aspects of communication and orientation of behavior in sperm whales (Physeter macrocephalus).
Rough surfaces characterization using a time-reversal mirror
Authors: Roux Philippe , Fink Mathias , Rose James H.
Published: July 2002

A new method is described for determining the rms height and autocorrelation function of rough surfaces using measurements made with an acoustic time-reversal mirror (TRM). First, the TRM insonifies the surface and the backscattered wave is recorded and time-reversed. Second, the TRM is displaced parallel to the surface and, at each displacement the previously recorded time-reversal wave is rebroadcast. For zero displacement the time-reversed wave is matched to the surface and the original incident pulse is recovered (upon reflection of the rebroadcast wave). However, with increasing displacement the signal ceases to resemble the incident pulse. The decorrelation of the signal allows one to characterize the surface. Measurements are reported for a number of periodic and random rough surfaces.
Progress in silicon microphones
Authors: Sessler Gerhard M.
Published: July 2002

Recently, several advances have been made in the design, technology, and performance of silicon microphones. New or significantly modified transducers are: (1) condenser microphones consisting of a single chip processed with sacrificial-layer technology to form the electrode-air gap system; (2) condenser microphones with small parasitic capacitance to decrease the load on the sensor output; (3) optical-waveguide microphones utilizing novel waveguide designs and operating with intensity modulation, which, to date, has not been used in acoustic silicon sensors. Also, attention has been given to various types of ultrasonic silicon microphones for airborne sound. Of importance in all implementations is the equivalent noise level, which is, in some microphone-preamplifier systems, sufficiently low for certain applications, but still higher than for conventional microphones. The present state of the art with respect to transducer design and performance will be discussed.
Experimental study on the accuracy of sound power determination of S. I. scanning method
Authors: Yano Hiroo , Tachibana Hideki , Suzuki Hideo
Published: July 2002

In ISO/TC43/SC1/WG25, the precision method of sound power determination by sound intensity scanning method is being drafted as the third standard of ISO 9614 series. For this drafting work, some experimental studies were performed on the measurement accuracy, the methods for checking the measurement sound field (field indicators), and practical procedures of signal processing during the scanning. The sound power determination was made for artificial sound sources (a reference source and a sound source system consisted of two loudspeakers) and actual noise sources (a vacuum cleaner and an air compressor) by changing such measurement conditions as the scanning density, the scanning speed, and the strength of the extraneous noise. From the experimental results, the validities of the specifications in the draft are examined.
Measurement of microphone random-incidence and pressure-field responses and determination of their uncertainties
Authors: Gramtorp Johan , Frederiksen Erling
Published: July 2002

For many applications it is important to know the frequency response of the measurement microphone. In an earlier paper the determination of the free-field response and the uncertainties of the responses based on actuator calibration for 1/2″ microphones was discussed [J. Gramtorp and E. Frederiksen, J. Acoust. Soc. Am. 100, 2672 (1996)]. This paper continues by discussing the determination of the pressure-field and random-incidence responses and the determination of their uncertainties. The pressure-field responses are based on estimated pressure-field corrections obtained using the pressure-field reciprocity technique and electrostatic actuator calibration. The random-incidence responses are based on a large number of free-field measurements with different angles of incidence increased in small steps, and calculated according to IEC 1183, combined with electrostatic actuator calibration. From most manufacturers no information on the uncertainties is available, but a complete set of uncertainty values for pressure-field and random-incidence corrections and responses for the new Bruel & Kjaer Falcon Range microphones will be presented and discussed.
Studies in bowing point friction in bowed strings
Authors: Schumacher Robert. T.
Published: July 2002

By using force transducers at the terminations of a violin E string, one may reconstruct the force and velocity at the bowing point that produces those termination forces [R. T. Schumacher and S. Garoff, Institute of Acoustics, Proceedings, Vol. 19: Part 5, 43–48 (1997) (ISMA’97)]. That information, combined with examination of the ‘‘friction track’’ [R. T. Schumacher and S. Garoff, CAS J. 3(2), 9–16 (1996)] allows the possibility of determining the frictional properties of the rosin-mediated bow–string interaction. The reconstruction of the force, f(t), and velocity, v(t), allows determination of the force–velocity relation F(v). That reconstruction is a delicate operation requiring careful measurement of the reflection functions of the transverse waves at the terminations. Use of simulations aids in determining the limitations of the reconstructions. Knowledge of F(v), combined with examination of the friction track, variation of the chemical constituents of the rosin, and chemical preparation of the string surface, as well as measurements of the rosin’s physical properties, such as softening temperature and x-ray structural examination, will eventually establish the physical basis for the alternating adhesion–lubrication properties of the rosin that produce the slip-stick string oscillation.
Investigation of intermittency in the noise exposure pattern of longwall coal miners
Authors: Burks J. Alton , Bartholomae Roy C.
Published: July 2002

It is generally recognized that intermittent exposures to noise are less hazardous than continuous exposures with the same energy. This effect has been accounted for in the USA with the use of a 5-dB exchange rate, instead of the 3-dB rate associated with the equal energy principle. However, the appropriateness of the 5-dB exchange rate for assessing the risk of noise exposures in mining has never been examined closely. The authors have previously reported the results of a worker noise exposure survey conducted at six longwall coal mines [R. C. Bartholomae and J. A. Burks, Proceedings: NOISE-CON ’94, 1017–1022 (1994)]; the time-resolved dosimeter data from that study were reanalyzed to determine if the noise exposure pattern of longwall miners can be categorized as intermittent. For this purpose effective quiet is defined to be a period of time in which the sound level is less than 75 dBA [W. Melnick, J. Acoust. Soc. Am. 90, 147–154 (1991)] for 10 s or longer [K. D. Kryter, The Effects of Noise of Man (1985), p. 273]. It is found that the miners experience an average of 125 periods of effective quiet and an average total quiet time of 1.7 h on a daily basis.
Occupational noise and solvent exposure in the printing industry
Authors: Ferris Rande , Groothoff Beno
Published: July 2002

The study examined the effects on hearing from occupational noise and solvent exposure in the printing industry and was conducted by measuring a selection of workers’ daily noise dose, sampling personal solvent exposures and audiometric testing before and after shifts for the detection of a hearing threshold shift. Audiometric test results were inconclusive due to the inadequate testing areas provided at each workplace. Personal monitoring confirmed that where solvent exposure occurs, high noise levels are usually also present. Fifty-three percent of the noise dose level measurements exceeded the statutory limit LAeq,8h of 85 dB and a further 9% exceeded the limit of 140 dB (Lin). Twenty-two percent of the analyzed solvent exposure samples revealed benzene, with 5% exceeding the worksafe exposure standard of 16 mg/m3. The lack of essential information contained in Material Safety Data Sheets (MSDSs) for substances used in the printing industry was highlighted. Accurate MSDSs are required to assist employers in discharging their obligation to provide correct information about hazardous substances to employees under the Workplace Health and Safety Act of 1995, as well as the hazards associated with those substances. Better information is required in an MSDS, from manufacturers and suppliers, as to the specific properties and health hazards of a hazardous substance.
Under which conditions is sonochemistry able to give information about the so-called extreme conditions prevailing inside the collapsing bubbles?
Authors: Reisse Jacques , Bartik Kristin , Segebarth Nicolas
Published: July 2002

Sonochemistry is able to give information about the extreme conditions prevailing inside collapsing bubbles. However, this information is obtained only when the experimental data correspond to primary chemical steps taking place in the gas phase inside the bubbles. This is unfortunately often not the case: The experimental data correspond, in the majority of cases, to secondary reactions taking place either in a shell around the collapsing bubble or in the bulk liquid. The short introductory talk to the sonochemistry session will be devoted to trying to answer the following questions: How must reactions, able to give relevant information about the so-called extreme conditions inside the bubbles, be selected? What is the actual reaction zone inside the bubble and what are the temperature limits for this zone? Is it certain that the ‘‘active zone’’ for sonochemistry is always the same as the ‘‘active zone’’ for sonoluminescence? Why does sonochemistry involve radicals instead of ions?
Sonoluminescence and sonochemistry in aqueous solutions containing surface active solutes
Authors: Grieser Franz , Ashokkumar Muthupandian , Barbour Katrina
Published: July 2002

The ultrasound induced reduction of gold chloride in aqueous alcohol solutions has been measured and compared with the extent of sonoluminescence (SL) quenching observed in the same solutions, as a function of alcohol concentration. Both ultrasound initiated phenomena were found to be directly related to the Gibbs surface excess concentration of the alcohol at the gas/water interface. The SL quenching occurs in two distinct surface excess regimes. The first region accounts for about 90% quenching of the SL signal. The second quenching region extends over a broader surface excess range and the profile matches the extent of enhancement in the reduction of gold chloride. When the nonvolatile surfactant sodium dodecylsulfate (SDS) was used instead of alcohol, the trends in the SL signal and in the sonochemical reduction process were quite different. At low concentrations (<2 mM) of SDS, the SL signal was enhanced over that obtained from water without surfactant. At higher SDS concentrations, the SL signal declined and leveled off to about 80% of the water signal at about 10 mM. In contrast, the reduction of gold chloride increased to about 8 mM SDS and then remained constant above this value. Possible mechanisms that explain the results will be presented.
Development of solid state nonlinearity
Authors: Breazeale M. A.
Published: July 2002

The nonlinear acoustics of solids developed from the nonlinear acoustics of fluids. Originally, the problem was to undo correctly the Hooke’s Law assumption without losing nonlinear terms. At present, one problem is to find a use for nonlinear acoustics of solids. The first problem has been solved; the second one is an ongoing one. It is the reason for special sessions. To develop geological exploration based on nonlinear acoustics, at first it was thought that nonlinear acoustics of crystalline solids would do. Now it is known that other nonlinearities must be considered. The purpose of the present paper is to show how solid state nonlinear acoustics developed, how nonlinear acoustics of crystals requires only one nonlinear term, and to give evidence of the fact that the subject needs to be expanded.
Acoustic nonlinearities in earth solids
Authors: Ostrovsky Lev A. , Johnson Paul
Published: July 2002

Nonlinear elastic response in earth solids is a robust and representative physical characteristic. In this lecture the evidence leading to this conclusion is presented by providing an overview of theoretical and experimental developments in the domain. Illustrated measurements include those of nonlinear response in rock from a variety of dynamical wave experiments. The evidence leads to a pattern of unifying behavior. Nonlinear elasticity in earth solids is large relative to most materials; hysteresis and ‘‘discrete’’ memory play an important role in nonlinear properties of earth solids; nonlinear response is evident over a large frequency interval (dc to several MHz at least); and nonlinear response is significant, as is commonly appreciated, at large static and dynamic strain levels, but also at small strains where this behavior and the manifestations of this behavior are commonly disregarded. Recently, the methodology for extracting the nonlinear coefficients for a material have been proposed. Some theoretical models of structural nonlinearity of solid media and of wave propagation in such media are also described.
Measurements of surface-wave harmonic generation in nonpiezoelectric materials
Authors: Hurley Donna C.
Published: July 2002

Methods for exciting surface waves suitable for harmonic generation experiments in nonpiezoelectric materials have been investigated. Such methods are needed for improved characterization of engineered surfaces. Unlike conventional ultrasonic techniques, nonlinear experiments require the ability to produce finite-amplitude, spectrally pure surface waves. Comb structures were selected from the methods evaluated, because they appear to offer the greatest potential for harmonic generation experiments on arbitrary substrates. The out-of-plane component of the surface waves was measured using a Michelson interferometer. The apparatus enabled direct measurement of absolute displacements with a spatial resolution of approximately 50 μm. Using this combination of excitation and detection techniques, the evolution of narrowband surface waves in the 1–10 MHz range was studied. Displacement amplitudes as large as 35 nm at a fundamental frequency of 10 MHz were observed. The spatial behavior of the fundamental and second-harmonic displacements indicated that, for correct interpretation, it was necessary to account for diffraction and other geometrical effects. Quantitative results will be presented for a variety of experimental configurations, including different substrates and comb shapes. Experimental results will also be compared to predictions of available theories for nonlinear surface wave propagation.
Nondestructive flaw detection in a solid medium using nonlinear acoustic effects
Authors: Song C. M. , Jung K. I. , Yoon S. W.
Published: July 2002

In a solid material it is very difficult to find tiny defects or cracks with the conventional linear acoustic techniques as nondestructive evaluation methods. When defects exist in a material, nonlinear acoustic responses become dominant in a propagating medium and can make it possible to detect such defects. As an application of such nonlinear acoustics, a nonlinear acoustic modulation technique for nondestructive flaw detection described in previous work [Kim et al., J. Acoust. Soc. Am. 101, 3029 (1997)] was applied to several different sample materials to confirm its feasibility. The second harmonic measurements can easily indicate existence of tiny defects or cracks in the samples. The time-delay measurements of the modulated sum and difference frequency signals can accurately locate defects in aluminum, steel, and brass solid rods, respectively.
Perceiving talking faces: Insights into attention
Authors: Massaro Dominic W.
Published: July 2002

Perceivers naturally integrate auditory and visual information in the perception of speech and emotion. Although both modalities contribute to perception, instructions and intention appear to modulate the impact of these modalities. Although there is some influence of the to-be-ignored modality, perceivers can attenuate its influence so that some degree of control is possible. The fuzzy logical model of perception provides a good account of performance under the different instruction conditions. For the estimation of the free parameters corresponding to the parameters that correspond to the evaluation of the auditory and visual sources, the FLMP assumed different parameter values in the different instruction conditions. Different parameter values were sufficient to capture the results. Intention can thus be accounted for in terms of information with no qualitative changes in information processing. Within the framework of the FLMP, the fundamental pattern recognition algorithm does not change. Bearing out this assumption, intention can enhance or attenuate the information contribution of sources that are available, but intention does not seem capable of enforcing another type of pattern recognition algorithm. Future research using expanded factorial designs should be able to provide a more definitive understanding of the role of intention and attentional set in pattern recognition. [Work supported by NIDCD.]
Full-spectrum-based acoustic spectroscopy for determining elastic and damping constants in forced-free bars
Authors: Guo Qiushuang , Brown David A.
Published: July 2002

Elastic moduli and damping have been previously determined by measuring the resonant frequencies and quality factor of a virtually free–free bar. The development of a complete analytical solution to the longitudinal wave equation including damping effects for a bar freely supported, driven at one end, and under the influence of transducer mass and stiffness at both ends was previously reported on [Qiushuang Guo and David Brown, ‘‘Effects of transducer mass on resonance frequency and quality factor of free-free bar,’’ J. Acoust. Soc. Am. 101, 3062 (1997)]. The analytical solution to the torsional and flexural waves in a bar including damping effects will be reported on here. When the entire spectrum of data is used, a more accurate determination of elastic moduli and internal damping coefficient is obtained. [Work supported by the University of Massachusetts—Dartmouth.]
Statistical analysis of boundary sound absorption in a panel-cavity system
Authors: Sum K. S. , Pan J.
Published: July 2002

Sound absorption due to acoustic-structural coupling has a significant effect on the acoustical behavior of an enclosed sound field in vibroacoustic systems. In the high-frequency range, this absorption is related to the average behavior of acoustic and structural modes and a statistical description (e.g., statistical energy analysis) of the coupling and its effect on the sound field response is well known. In both the low- and medium-frequency ranges, acoustic-structural coupling of low-order modes tends to dominate and there are large variations in acoustical behavior between acoustic modes. Therefore accurate modal description of the sound field boundary conditions is now important. However, in the medium-frequency range, the complicated boundary conditions are difficult to describe due to the presence of a large number of dominant acoustic and/or structural modes. Thus acoustic-structural coupling is not well understood and the physical interpretation of sound absorption in this frequency range is not clear. The aim of this paper is to obtain some physical insights in the behavior of sound absorption due to acoustic-structural coupling at medium frequencies. The coupling is statistically analyzed for a panel-cavity system and its physical relationship to the boundary sound absorption is illustrated.
Sound transmission through multilayer structures with isotropic elastic porous materials
Authors: Atalla Noureddine , Panneton Raymond , Tournour Michel , Amedin Celse K.
Published: July 2002

This paper discusses the prediction of transmission loss through multilayer structures with porous materials. First, a brief review of recent formulations for multilayer structures with poroelastic materials is presented. Second, the transmission loss problem is described and formulated using a coupled finite element and boundary element procedure. Issues such as poroelastic-elastic coupling, poroelastic-fluid coupling, and radiation from a poroelastic material will be addressed. The developed model is validated through numerical examples. Its advantages and limitations are discussed. Finally, typical results showing the vibroacoustic effects of several parameters such as the multilayer configuration, the types of porous materials, and the mounting conditions are presented. [Work supported by Bombardier, Inc., Canadair and N.S.E.R.C.]
A comparison of Hankel transform algorithms’ performance in shallow-water waveguides and their effect on the determination of seabottom plane-wave reflection coefficients
Authors: Cox Ben , Joseph Phillip
Published: July 2002

Complex acoustic pressure data as a function of range may be decomposed into its constituent wave-number components by taking the Hankel transform. This paper investigates the accuracy of a number of discrete Hankel transform algorithms applied to computer simulated pressure data in a shallow water channel for a variety of seabed bottom types. The results are compared against the exact solution and the most accurate algorithm identified for shallow-water applications. The differing behavior of these algorithms is illustrated by their use in the Hankel transform method proposed by Frisk et al. [J. Acoust. Soc. Am. 68, 602–612 (1980)] for the determination of seabottom plane-wave reflection coefficients. The results from computer simulations and scale model tank experiments are compared.
Shallow-water salmon and herring detection using 100-kHz sidescan sonars
Authors: Trevorrow Mark V. , Farmer David M. , Pedersen Bjarke
Published: July 2002

Acoustic results of fish detection using fixed 100-kHz sidescan sonar installations in the Fraser River (British Columbia) and in the Oresund (near Copenhagen, Denmark) are reviewed. Looking transverse to the river flow, echo traces due to migratory salmon were observed at ranges up to 250 m in water 6 to 13 m deep. The salmon trajectories were readily identified and counted against the background of reverberation from the river surface and bottom sediments. Similarly in the Oresund, long-term monitoring detected migrating herring schools above background reverberation at ranges up to 500 m in water 10 to 13 m deep. In both cases, occasional strong backscatter interference from vessel wakes and wind-induced surface bubble layers was observed. In the Oresund, changes in acoustic propagation conditions due to bottom inflow of more saline oceanic water drastically reduced fish detectability. For salmon in the river, acoustic multipaths due to boundary reflections were distinguishable from direct echoes at ranges up to 150 m. The general problems of shallow-water boundary reverberation and multipath reflection focusing will be reviewed, with discussion on how to compensate for these waveguide effects.
Sound scattering from a few scatterers: Application to swimbladder fish
Authors: Ye Zhen , Alvarez Alberto
Published: July 2002

This paper presents a general method for describing sound scattering by an ensemble of a few scatterers. A scheme is developed for calculating the effective scattering function of such an ensemble, including all orders of multiple scattering between targets. The method is then applied to low-frequency sound scattering by small fish schools. It is shown that in the backscattering, certain regular patterns in scattering appear as a result of interference rather than multiple scattering, when the fish form an ordered structure. The interference peaks are due to in-phase scattering, and can be explained by the Bragg reflection mechanism. Such regular interference patterns are gradually degraded, as the random deviation in each individual fish location from its mean position increases. For a completely random distribution of fish, the model recovers the results from the random-phase approximation. For the forward-scattering case, it lacks either the regular or the noisy interference. The scattering strength seems rather smooth, and may be well approximated by the incoherent summation of forward-scattering function of each individual fish. The scattering by partially or perfectly ordered fish schools is hardly distinguishable from that by totally random distributions of fish in the forward direction. [Work supported by the National Science Council and the Spanish Ministry of Education.]
Design and development of PC-IMAT: Teaching strategies for acoustical oceanography, part II
Authors: Hurley Lee Anne , Thomas Kevin M. , Korman Murray S. , Schuler John W. , Holmes Eleanor
Published: July 2002

The PC-IMAT (Personalized Curriculum for Interactive Multisensor Analysis Training) project is proving to be a flexible and effectively evolving computer-based training/educational platform needed to help tackle ASW and other tasks which require extensive analysis, classification, and interpretational skills. Midshipman taking SP411 (Underwater Acoustics and Sonar) are currently using PC-IMAT [J. Acoust. Soc. Am. 101, 3096A (1997)] to help investigate effective instructional strategies which convey understanding of a complex multivariate domain (like ray trace or propagation loss models). Classroom demonstration lectures and out-of-class projects allow students to successfully interact with experimental apparatus and make actual measurements (e.g., Fourier analysis, detection theory, beam pattern functions, sound speed versus temperature, computer ray tracing, reflection and transmission at an interface, and target strength versus angle of a scale model sub). However, a link between textbook theories, the actual physics experiments, and the real world setting of tactical sonar has been missing. Usage of PC-IMAT on actual submarine training exercises shows the limitations and enhancements of tactical maneuvering when sonar systems are subject to complex surroundings. The research and development of ‘‘scientific visualization’’ on PC-IMAT should ultimately incorporate a strong link between both learning environments. [Work supported by ONR.]