bluuebunny/crossref_metadata_2025 huggingface dataset:
Individual magnitude estimation functions and their relation to the Pacinian (P) and non-Pacinian (NP) channels
Authors: Bolanowski Stanley J. , Gescheider George A. , McDonnell Karen A. , Verrillo Ronald T.
Published: October 2005

Four distinct channels of information can combine to signal the sensation magnitude of tactile stimuli. For example, a 250-Hz vibratory stimulus of large size (2.9 cm2) and of low/moderate intensities activates the P channel, but at higher intensities the NP channels also are activated. Because of saturation and the potentially different functional properties of the various channels, crossing from one channel (e.g., P) to another (e.g. NP II) along the intensity domain may result in breaks in the overall sensation magnitude functions. Absolute magnitude estimation (AME) experiments were performed on six observers [250 Hz and narrow-band noise (175–350 Hz), 700-ms duration, 500-ms rise/fall time, thenar eminence, 2.9-cm2 contactor size; 15, 30, 40 °C skin surface temperature]. Results of individual observers were of particular interest since averaging across observers can obscure breaks due to idiosyncratic differences in their location. As previously shown, the averaged AME functions approximated power law relationships. The individual functions, however, were scalloped in shape with breaks that coincided with the individual P/NP II crossovers. Other breaks occurring at SL levels below the NP II threshold may be explained by the manner in which P corpuscle fibers entrain to vibratory stimuli and how this entrainment is disrupted by noise. [Work supported by NIH Grant Nos. DC00380 and DC00098.]
Stories about F. V. Hunt’s Acoustics Research Laboratory (Harvard) and about nonlinear acoustics
Authors: Blackstock David T.
Published: October 2005

Ted Hunt’s Acoustics Research Laboratory developed at Harvard University after World War II, a kind of academic follow-on to the Harvard Underwater Sound Laboratory. What distinguished the Harvard acoustics program was the very wide breadth of interests Hunt had in acoustics−engineering, physical, architectural, underwater, and historical. The choice of topics offered to his students was therefore correspondingly broad. In the second part of this talk, several tales of nonlinear acoustics will be recounted. [Review supported by ONR−from many different eras.]
Parabolic-equation modeling of global-scale acoustic propagation in the ocean including comparison with Heard Island experimental results
Authors: Collins Michael D. , Heaney K. D. , Kuperman W. A. , McDonald B. E. , Baggeroer Arthur B. , Mikhalevsky Peter N.
Published: October 2005

An adiabatic normal-mode model was previously applied to explain the arrival structure of signals propagating between nearly antipodal points [Heaney etal., J. Acoust. Soc. Am. 90, 2586–2594 (1991)]. To investigate the role of mode coupling, an approximate full-wave version of this solution has been implemented based on solving a two-dimensional parabolic equation (PE) along modal ray paths. For 57-Hz propagation from Heard Island to California, a finite-difference solution of the energy-conserving PE is obtained with an Iris workstation in nearly real time (i.e., the computation time is comparable to the propagation time). This solution agrees with data received on a vertical array at a site off California during the Heard Island Feasibility Test (HIFT) [Munk etal., J. Acoust. Soc. Am. 90, 2328–2331 (1991)]. In particular, the PE predicts the experimental result that the received energy is concentrated near mode five. Energy migrates in depth with the sound channel starting near the ocean surface at Heard Island, reaching a maximum depth near the equator, and moving back toward the ocean surface approaching California. Significant mode coupling occurs off the southeast coast of New Zealand due to interaction with the seafloor and the Antarctic Circumpolar Current (ACC). Mode coupling due to the ACC was previously predicted for a shorter HIFT path by Shang etal. [J. Acoust. Soc. Am. 90, 2348 (1991)]. a)Permanent address: Planning Systems, Inc., McLean, VA 22101.
Attenuation of low-frequency sound in shallow water
Authors: Mellen Robert H. , Browning David G.
Published: October 2005

The dominant low-frequency sound absorption mechanisms in seawater are pH dependent. Since, for a given depth, pH values can vary significantly from ocean to ocean, the corresponding attenuation will vary also. This is most striking at the depth of the deep sound channel axis where, for example, the values of low-frequency attenuation in the North Pacific Ocean are only one-half those in the North Atlantic. Surface waters throughout the oceans, however, have a uniformly high pH due to universal interaction with a well-mixed atmosphere. As a result, shallow water of all oceans should have a relatively uniform and high attenuation. This attenuation is similar to measured values in deep water surface ducts. Examples are given for several shallow-water locations.
Binaural recordings from KEMAR mannequin in several acoustical environments
Authors: Kulkarni Abhijit , Woods William S. , Colburn H. Steven
Published: October 2005

In the development and evaluation of virtual acoustic displays, the relative importance of factors such as head movement, listener-specific pinna responses, and naturalness of the environment to the veridical localization of sound (including externalization) remains unclear. In this poster demonstration, the role of reverberation is explored through a series of recordings from an artificial head in a variety of acoustical environments. Specifically, several binaural recordings have been made on the acoustical mannequin KEMAR for single and multiple talker configurations in a variety of different environments and in a number of different conditions. The signals from KEMAR’s microphones (Etymotic ER−1/2 in.) were amplified (ER-11 amplifiers provided with microphones) and fed directly to a commercially available digital audio tape (DAT) machine. These recordings will be available for listening and discussion at the poster. [Work supported by NIDCD.]
On-line learning without forgetting for language acquisition
Authors: Agrawal A. , Mammone R. J.
Published: October 2005

In this paper, a new method for on-linetraining that overcomes interference in neural networks is presented. The language acquisition problem is modeled as a system of linear equations as first given by Gorin etal. [A. Gorin etal., ‘‘Adaptive Acquisition of Language,’’ in NeuralNetworks, TheoryandApplications, edited by R. J. Mammone and Y. Y. Zeevi (Academic, New York), p. 125]. The new method encodes data patterns or words that have been learned previously as a set of convex constraints. On-line training is then implemented using the row action projection (RAP) algorithm to readjust the weights subject to these convex constraints. The RAP algorithm asymptotically converges to the pseudoinverse solution in the case of simple linear constraints. The computational complexity of conventional methods of calculating the pseudoinverse make them unsuitable for on-line applications. The previously learned patterns are viewed as long-term memory while the on-line data is considered to reside in short-term memory. Memory retention is obtained in the new approach by storing the patterns that are close to the feature space boundaries in long-term memory. These stored patterns are then used as convex constraints for any subsequent on-line learning. In contrast to previous block learning strategies, the new approach learns the meaning of words sequentially. This enables the on-line training of a connectionist network. Computer simulations are presented that demonstrate the memory retention capabilities of the new on-line training algorithm.
Metaphoric learning for language acquisition
Authors: Naik D. K. , Mammone R. J.
Published: October 2005

A new approach to adaptive language acquisition is presented. Previous methods for language acquisition have used an information theoretic approach to determine the connection between words and actions. A novel approach to language acquisition was recently developed, where a linear neural network is adaptively trained to map a set of words into a specified set of actions [A. Gorin etal., ‘‘Adaptive Acquisition of Language,’’ in NeuralNetworks, TheoryandApplications, edited by R. J. Mammone and Y. Y. Zeevi (Academic, New York), p. 125]. This training can be used as a knowledge source to guide a neural network in acquiring associations more quickly in learning related tasks. This generalization of learning one task to help guide the learning of a related task is called metaphoric learning or learningbylearning. A new method for metaphoric learning in neural networks is presented. The method uses an observing neural network called a meta-neural network (MNN) to direct the training of a conventional word-to-action mapping neural network. The MNN provides the conventional neural network with gradient information that is based on successful training strategies acquired previously. If the conventional neural network is exposed to words that are similar to those learned previously, the MNN is shown to improve the learning rate. The proposed scheme can also be applied to the problem of learning of different languages that are structurally similar to a language learned previously. Computer simulation results are presented that demonstrate improved learning rates for related language acquisition tasks.
Downslope conversion in oceanic sound propagation: CENTRO/ANTS code interpretation
Authors: Yuan J. R. , Überall H. , Hodgkiss W. S.
Published: October 2005

The 1989 experiment by the Scripps Marine Physical Laboratory, studying sound propagation down the continental slope off Pt. Arguello and Pt. Conception, CA, has furnished evidence for the downslope conversion effect in which sound propagating down from a source over the continental shelf, by its interaction with the sloping ocean floor, gets trapped into the sound channel. As a consequence, the horizontal arrival structure observed at a distant receiver over deep water (the Scripps FLIP array, in this case) shows a flat ‘‘pedestal’’ shape centered at ±20° about the horizontal, while with a source also over deep water, a central minimum would be apparent due to Snell’s law. Our calculations, using the CENTRO/ANTS normal mode code written by J. I. Arvelo and developed further at Catholic University, bears out the pedestal shape of the arrival structure. In these calculations, downslope propagation is treated adiabatically, and the bottom structure (sediment with underlying rock) is correctly taken into account. [Work supported by the ONR.]
Eliminating phase errors in parabolic equation propagation models by perturbing the index of refraction
Authors: Wood David H.
Published: October 2005

For a fixed index of refraction, solutions of a parabolic equation consist of local normal modes added together using phase factors that are distortions of those of the Helmholtz equation. A method is presented for perturbing the index of refraction in such a way that the distortedphasefactors using a parabolic equation with the perturbed index are precisely the same as the desiredphasefactors that would have been obtained from the Helmholtz equation with the original index of refraction. The phase errors of numerous types of parabolic equations can be be eliminated in this way because the analytic form of the distortion of the phase factors follows from whatever formula has been used to approximate a certain square root. In addition, the perturbation of the index of refraction can be efficiently updated at each range step in a range-dependent environment.
Modeling and numerical method in the medium frequency range for vibroacoustic predictions using theory of structural fuzzy
Authors: Soize Christian
Published: October 2005

In linear dynamic analysis of complex mechanical systems, the structural fuzzy is defined as the set of minor subsystems that are connected to the master structure but are not accessible by classical modeling. The notion of master structure is presently extended to other elements such as an external dense compressible fluid strongly coupled with the primary structure. For the low-frequency (LF) dynamic analysis, the modeling of the structural fuzzy is commonly made with a system of masses. If the LF modeling of the structural fuzzy is applied in the medium-frequency (MF) domain, there result some large differences between calculations and experiment. It is therefore necessary to take into account internal degrees of freedom of the structural fuzzy. A global probabilistic modeling of the structural fuzzy is proposed to improve the calculated estimates of the MF vibrations into the master structure and of the far field radiated by itself. In this paper, (1) a probabilistic modeling of the structural fuzzy is presented, (2) a probabilistic behavior law of the structural fuzzy is built, (3) the random vibrations in the master structure with a structural fuzzy and the far field radiated are studied, (4) the numerical analysis needed to implant the method is presented, and (5) numerical simulations on standard structures and on a complex industrial submarine structure are shown.
Notions and concepts in statistical energy analysis revisited
Authors: Maidanik G. , Dickey J.
Published: October 2005

The notions and concepts that helped develop and sustain the statistical energy analysis (SEA) are briefly reviewed and assessed. Particular attention is given to the division of a complex into constituent dynamic systems. It is argued that the division has a decisive role in the successful application of SEA. Indeed, the appropriate division may be dependent on the frequency range of interest. Modal groupings within each dynamic system are also discussed. When modes can be distinctly categorized; e.g., by their couplings to modes in other dynamic systems, it may become advantageous to group the modes into categories. Illustrations are cited in terms of complexes that can be modeled by coupled one-dimensional dynamic systems.
Backscattered echoes from submerged elastic shells insonified by short realistic pulses using Wigner-type distributions
Authors: Gaunaurd G. C. , Strifors H. C.
Published: October 2005

Significant features in the backscattered echoes of shells insonified by idealized pulses were studied earlier [J. Acoust. Soc. Am. 91, 2384 (A) (1992)], in the frequency, the time, and particularly in the combined time–frequency (t–f) domain. In this last case, (Gaussian) time-windowed Fourier transforms (TWFT) and pseudo-Wigner distributions (PWD) of the returned pulses were used. This analysis is now extended here to finite, realistic, incident pulses, with either rectangular or sinusoidal envelopes. The above distributions extract from the returned pulses the time-evolution of the resonances the target may have in the chosen (broad) band of operation. This band includes the so-called medium-frequency range. The selection of suitable carrier frequencies produces t–f-domain displays with recognizable features linked to specific target characteristics. One of these is, for example, the mid-frequency enhancement ‘‘hump,’’ present at ‘‘coincidence,’’ which determines the shell thickness. Adjusting the time-window widths controls the amount of detail in the displays, which will be shown in an informative colorized format in 3-D.
Comparison of exact and weak-coupling estimate of energy distributions in connected flexural beams
Authors: Bremner Paul , Constantine Paris , Kasper Peter
Published: October 2005

In previous publications, the authors have proposed an approximate ‘‘weak coupling’’ formulation for mechanical power flow between arbitrary vibrational substructures. Simple numerical examples have shown this formulation asymptotes to the statistical energy analysis (SEA) result at higher frequencies, when a large population of vibratory modes contribute to the substructure energy level, in any frequency band. This paper evaluates the accuracy of the formulation at low frequencies and low-modal density by comparison with ‘‘exact’’ energy distributions derived from the dynamic stiffness method. The results indicate that weak coupling modal power formulations are more accurate than SEA predictions in this domain. The current work highlights the importance of rigid body modes of the uncoupled substructures and the phase correlation and cross coupling of force and moment power transmission components at a structural junction.
The effect of irregularity on the scattering of acoustic waves from a ribbed plate
Authors: Photiadis Douglas M.
Published: October 2005

The scattered field from an irregularly ribbed fluid-loaded plate is ‘‘measured’’ using numerical simulations. The diffuse field scattered by the irregularity exhibits strong coherent features in the far-field scattering pattern associated with phase matching to locally propagating Bloch waves on the structure. These features are also apparent in the scattering from finite periodic arrays, but are strongly enhanced by irregularity. Some examples of the behavior of the system are presented and the scaling of the cross section with the number of scatterers and irregularity is determined.
Statistical grammar inference
Authors: Schabes Yves
Published: October 2005

Language can be talked, written, printed, or encoded in numerous different ways. As any form of communication, each of these codings can be analyzed statistically for the purpose of comparative judgment and predicting power. Early proposals of language models such as Markov models, N-gram models [C. E. Shannon, Bell Syst. Tech. J. 27(3), 379–423 (1948)] although efficient in practice, have been quickly refuted in theory since they are unable to capture long distance dependencies or to describe hierarchically the syntax of natural languages. Stochastic context-free grammar [T. Booth, in 10th Annual IEEE Symp. on Switching and Automata Theory (1969)] is a hierarchical model that assigns a probability to each context-free rewriting rule. However, none of such proposals perform as well as the simpler Markov models because of the difficulty of capturing lexical information [Jelinek etal., Tech. Rep. RC 16374 (72684), IBM, Yorktown Heights, NY 10598 (1990)] [K. Lari and S. J. Young, Comput. Speech Lang. 4, 35–56 (1990)] This is the case even if supervised training is used [F. Pereira and Y. Schabes, in ACL ’1992]. Stochastic lexicalized tree-adjoining grammar (SLTAG) has been recently suggested as the basis for training algorithm [Y. Schabes, in COLING ’1992]. The parameters of a SLTAG correspond to the probability of combining two structures each one associated with a word. This system reconciles abstract structure and concrete data in natural language processing since it is is lexically sensitive and yet hierarchical.

The need for a lexical and still hierarchical statistical language model is partially corroborated by preliminary experiments which show that SLTAG enable better statistical modeling than its hierarchical counterpart, stochastic context-free grammars. The experiments also show that SLTAG is capable of capturing lexical distributions as well as bigram models while maintaining the hierarchical nature of language.
Bandwidths and amplitudes of self-excited, flexible-walled cavity resonators
Authors: Mast T. Douglas
Published: October 2005

When a flexible-walled cavity resonator undergoes flow-induced (self-excited) oscillations in the presence of a grazing flow, its behavior can be fundamentally different from that of the same resonator undergoing forced oscillations. One difference is that the bandwidth of oscillations may be much narrower in the self-excited case: Q’s measured for this case are typically an order of magnitude higher than Q’s calculated using a simple lumped-element model. An explanation of this phenomenon is given, using the root-locus method of Cremer and Ising along with an approximate formulation for the impedance of the resonator opening. The impedance formulation incorporates ‘‘negative resistance’’ associated with instability of the mean flow, and nonlinear contributions to the resistance, which serve to limit the amplitude of oscillations. [Work supported by the William E. Leonhard Endowment to the Pennsylvania State University.]
Experiments on capillary wave turbulence
Authors: Wright William , Hiller Robert , Putterman Seth
Published: October 2005

Measurements of the response of a fluid surface to parametric excitation at a frequency that excites ripples, displays a number of qualitatively distinct regimes. As the amplitude is increased, standing waves (with higher harmonics) turn into a stationary, square ‘‘crystal,’’ pattern. At higher amplitudes, ‘‘dislocations’’ migrate through the pattern. While at the highest amplitudes, the spectrum becomes broadband with no discernable spatial pattern. Measurements are being made with a thin wire probe as well as the shadowgraph technique. The wire indicates that the broadband spectrum follows a power law: and the surface FFT indicates that many modes participate in the motion. Improvements in this absolute calibration are required before one can determine whether wave turbulence has been observed. [Work supported by the US DOE Division of Engineering and Geophysics and NASA−Microgravity.]
Concurrent pitch segregation based on AM
Authors: Sheft Stanley , Yost William A.
Published: October 2005

In a 2IFC paradigm, listeners indicated which of two concurrent harmonic complexes was amplitude modulated (AM). The fundamental of one complex was always 200 Hz and the fundamental of the other was either 220 or 245 Hz. Stimuli were three randomly chosen harmonics of both fundamentals. The harmonics of one fundamental were modulated in the first interval and those of the other in the second interval. The AM rate was either 5, 13, or 23 Hz. In control conditions the two harmonic complexes were presented sequentially in random order. Harmonic randomization significantly affected performance in all conditions. Even in conditions with the lowest variability (selecting three harmonics from a pool of four or five), performance levels for some subjects were below a d’ of 1.5. With coherent modulation in the concurrent pitch segregation task, performance came closest to the control conditions with the 45-Hz f0 separation, 5-Hz AM, and low variability in harmonic randomization. Incoherent modulation introduced by randomizing either modulator phase or rate made the task more difficult as did the addition of flanking tones unrelated to either f0. Results indicate that though dependent on stimulus variability, coherent AM can lead to spectral grouping for pitch segregation. [Work supported by NSF and AFOSR.]
Scaling the perceptual clarity of the presence or absence of target tones embedded in modulated noise maskers
Authors: Singh Punita G. , Bregman Albert S.
Published: October 2005

Perceptual judgments of the presence or absence of tones embedded in modulated noise maskers were obtained using a six-point rating scale (1=clearly absent, 6=clearly present). The maskers comprised four simultaneous noise bands centered at 500, 1000, 1500, and 2000 Hz, with bandwidths of all bands either 12.5, 25, 50, or 100 Hz. The bands were derived either from the same noise source by filtering and transposition, or from different sources, and were subsequently multiplied by same or different (phase shifted) modulators. A sine tone at the center frequency of one of the noise bands was used as the signal. A single noise interval was preceded by a cue tone that was either present or absent in the noise at a fixed S/N≊−13 dB SPL. The cue and noise intervals were both 400 ms long, and separated by 1 s of silence. Rating scores from ten normally hearing listeners were generally higher for tones embedded in maskers with common envelopes, indicating less masking and improved perceptual clarity of the tones. Common origin of noise source did not lead to improved audibility of the tones. There was no significant effect of tone frequency. However, bandwidth affected judgments significantly. For the 12.5- and 25-Hz bandwidths, the difference between modulation conditions was reduced, while false alarm rate increased substantially. These narrow-band noises apparently sounded tonal even in the absence of the signal, thereby receiving higher ratings. For the 50- and 100-Hz-wide maskers, the effect of modulation pattern was enhanced, and there were fewer false alarms. Similarity of amplitude envelopes within a masker has been invoked as a simultaneous grouping cue facilitating segregation of a concurrent signal.

It seems that sequential grouping factors such as similarity of perceptual attributes (e.g., pitch or timbre) of the cue and masker also play a role in signal detection. [Work supported by NSERC.]
Temporal resolution for frequency gliding signals and its relation to the phonemic perception of /b/ and /w/
Authors: MacNeil J. F. , Slawinski E. B.
Published: October 2005

The effects of age and hearing loss on amplitude and temporal resolution were examined. The first experiment assessed the perception of the phonemic distinction between three continua of /b/ and /w/ stimuli which varied in their amplitude envelopes. The degree of hearing impairment significantly effected the importance of the type of acoustical cue with hearing impaired listeners demonstrating a greater influence of the amplitude envelope and a shift in the phonemic boundary toward longer transition durations relative to normal listeners. The second experiment examined duration discrimination in a 2AFC task using a constant stimuli method for isolated analogs of the second formant transitions. Thresholds were interpolated from the 75% correct position from probits fitted to the psychometric function. The effects of both age and hearing status were significant, however the type of hearing impairment (shallow or steeply sloping) was an important factor in temporal resolution. Additionally, among listeners with normal hearing within the frequency range being tested elderly adults showed poorer temporal resolution relative to young adults.
Time-frequency representations of auditory signatures: Dynamic signal models
Authors: Scruggs Shelley E. , Wakefield Gregory H.
Published: October 2005

Signal theory provides a mathematical framework within which to pose questions of representation. Such theory establishes the minimum conditions for which signals can be represented uniquely, for example. Time-frequency distributions are often used as representations of the temporally varying spectral characteristics of acoustic signals. When one desires a correspondence between the distribution of a signal and the auditory perception of that signal, however, it is not clear how to proceed. Several researchers have approached the auditory representation problem within the domain of time-frequency distributions [M. D. Riley, SpeechTime-FrequencyRepresentations (Kluwer Academic, Boston, 1989) and W. Heinbach, Acustica 67, 113–121 (1988)]. In the present paper, an alternative approach is provided based on dynamic signal models and psychoacoustic spectral processing theory. This approach is applied to characterizing acoustic transients such as automotive starter sounds. A dynamic signal model is introduced and experimental results are presented concerning the ability of this model to uniquely characterize the signals of interest. Application of Terhardt’s Fourier t transform is also investigated [E. Terhardt, Acustica 57, 242–256 (1985)] and results are compared with other time-frequency distributions. [Work supported by a Bell Communications Research graduate fellowship, the Ford Motor Company, and a National Science Foundation PYI award.]
The ASA’s role in preventing nonoccupational hearing loss in the United States
Authors: Clark William W.
Published: October 2005

Recent evidence has suggested that exposure to excessive noise outside the workplace is making a significant negative contribution to the hearing of Americans, both young and old. Once considered a hazard only to those who worked where loud noise necessarily accompanied manufacturing processes, excessive noise exposure also threatens the hearing of individuals who engage in noise leisure activities such as hunting and sport shooting or listening to amplified music through headphones or in ‘‘boom box’’ automobiles. ASA can help to prevent nonoccupational hearing loss in several ways. The collective scientific and engineering expertise of ASA members should be exploited to conduct and report careful, quantitative studies on noise exposure associated with leisure activities. Recommendations concerning hazardous exposures can be developed by the ASA and disseminated to the public through the media, to manufacturers of noise products, and to appropriate regulatory bodies. Educational programs can be developed by the ASA for use in schools, 4-H clubs, scouting, gun clubs, and other community organizations. These efforts would increase the visibility of the ASA nationally, and may reduce the impact of nonoccupational noise exposure on Americans.
Achievable ways ASA can promote education about noise
Authors: Royster Julia Doswell , Florentine Mary
Published: October 2005

There is wide agreement that meaningful educational materials and curricula about noise are badly needed. However, without government funding, most current efforts in this area are voluntary projects by private individuals and professional groups. Popular press coverage of noise effects is often sensational, and media features seldom address noise control or effective hearing protection. Public awareness of noise issues needs to be raised to create a demand for quieter products and environments. ASA could take a leadership role by making available resource packs of materials that could be copied and used by society members, educators, health professionals, and others. Model educational units are needed for students from preschool through graduate school. Duplication masters of information brochures targeted at parents and consumers could be provided to influential professionals, retailers, and manufacturers. These strategies would not only serve the public, but would also raise the visibility of ASA without being prohibitively expensive.
How the Acoustical Society of America can assist industry in plant noise control
Authors: Roth Stephen I.
Published: October 2005

Industry should insure that its workers do not incur noise-induced hearing loss above that which is expected of the general population. Engineers should purchase new equipment that provides acceptable noise levels, and should reduce noise of existing factory equipment to proper levels. Unfortunately, many engineers are not knowledgeable in noise control techniques, and are not conversant in acoustical terminology. Many equipment manufacturers are not versed in noise control, cannot provide noise level information for engineers to make purchase judgments, and have not developed low-noise products. Many decision makers in industry do not understand the impact of high noise on their employees. ASA should influence universities to provide undergraduate acoustic education opportunities for students planning to become plant engineers. ASA should develop interest in the manufacturing sector to produce low-noise equipment, and to make product noise level information available. ASA should encourage the development of standards that assist plant engineers in making noise control decisions. ASA should take the lead in educating the general public, and industry on the consequences of high-noise level workplaces.
Nonlinear behavior of PZT ceramics at megahertz frequencies
Authors: Breazeale M. A. , Na Jeongkwan
Published: October 2005

The ceramic PZT often is used as a transducer. It can be polarized by raising the temperature above the Curie temperature and applying an electric field. It has exhibited many anomalous physical properties, however, and its nonlinearity is no exception. An increase in the nonlinearity parameter of two orders of magnitude near the Curie temperature and a frequency dependence even at room temperature have been observed. Such behavior is different from that of any solid that has been measured. Measurements of the anomalous nonlinear behavior of PZT are presented and mention is made of some technological implications of this behavior. [Research supported by Murata Corp.]
Multifrequency acoustic visualization and information retrieval (MAVAIR) system
Authors: Kirsch Jay
Published: October 2005

The oceanographic community has seen a sharp increase in the application of underwater acoustics to biological studies. While the emphasis has been on sensor development, only a few signal processing systems have been designed to handle the large amounts of data being generated. Moreover, these systems lag in speed, do not adhere to standards, and center around single frequencies. Future applications of bioacoustics will be limited by the ability to comprehend data being generated. A UNIX workstation-based multifrequency acoustic visualization and information retrieval (MAVAIR) system has recently been designed which is capable of acquiring, analyzing, integrating, and displaying multifrequency data. This integrated post-processing system includes an innovative signal acquisition scheme via DSP hardware, standard bioacoustical software algorithms, and flowgram-based interactive visualization of all parameters. The MAVAIR system should greatly shorten the bioacoustical post-processing task while being more universal and yet simple to use. Work to develop MAVAIR has enabled us to extract more biological information from the acoustical data. Examples of high-resolution fish scattering obtained from the prototype system will be illustrated.
Solid-state integrated microsensors
Authors: Najafi Khalil
Published: October 2005

The development of integrated sensors based on solid-state technology has become an important goal for many application areas. These devices are an important link for gathering, processing, and communicating information between many electronic systems and users, and the nonelectronic world in areas such as health, care, transportation, manufacturing, avionics, environmental monitoring, and many others. Significant advances have been made in developing new integrated sensors and microsystems: sensors for measuring pressure, acceleration, flow, image, vibration, strain, sound, and many others have been developed. This paper will review the state-of-the-art in integrated sensors and microsystems. It will briefly review the application of integrated circuit technology to micromachining and microsensors, and will provide examples of a few solid-state, silicon-based microsensors. Finally, the paper will discuss the impact that these devices have had on measurement and control systems, and will review future applications.
The case for magnetically driven microactuators
Authors: Busch-Vishniac Ilene J.
Published: October 2005

Recent attempts to build microactuators have centered on electrostatic actuators made of silicon. Three arguments have been repeatedly presented for favoring electrostatic approaches over magnetic: The stored energy densities are comparable or higher on micron scales, the efficiency can be higher, and the approach can be made compatable with semiconductor fabrication. In the work presented here, the arguments favoring electrostatic microactuators are reexamined and found to be flawed. In particular, magnetic fields are shown to be potentially greater than electrostatic fields even down to submicron scales, while the actuator efficiency is shown to be determined by the powering electronics rather than the actuator itself. Further, the need for a monolithic device based on semiconductor fabrication techniques is called into question by the incompatibility of most micromachining (3-D) and VLSI (2-D) processing steps. Other factors, such as robustness, suggest that the case for magnetic approaches to microactuators is quite strong.
Capacitive devices for the efficient transduction of ultrasonic fields in air
Authors: Schindel D. W. , Hutchins D. A.
Published: October 2005

Capacitive devices that are able to efficiently generate and detect ultrasonic fields in air have already been designed and manufactured. They consist of metallized insulating films resting upon rigid conducting backplates. In order to increase efficiency, the backplates must be roughened, providing a resonant air cushion behind the thin insulating films. Unfortunately, roughening by conventional mechanical means [D. W. Schindel and D. A. Hutchins, Proc. IEEE Symp. 1, 301–304 (1991)] will be shown to produce a transducer whose beam profile is highly nonuniform above several hundred kilohertz. Ways of overcoming this are being investigated, including the manufacture of backplates through irradiation of metals by high-intensity ultrasound and micromachining of silicon. The result of the characterization of such new transducers in terms of bandwidth, sensitivity and beam profiles will be given, along with a discussion of the versatility of air coupled transducers manufactured completely from integrated circuit processing techniques.
How ASA can assist the federal government in noise control
Authors: Suter Alice H.
Published: October 2005

ASA has a great opportunity to assist the federal government in promoting noise control, but has done little to exercise this opportunity over recent years. Industrial noise, aircraft and other transportation noise, and noise effects are probably the areas where ASA members can share their knowledge and expertise most effectively. They can testify at congressional hearings and send written materials to interested members of Congress. They can also supply information and testimony at many stages along the rule-making process and can assist in the implementation of these rules once they are made final. Federal employees are often unaware of improvements in instrumentation and new noise control methods or devices. Inspectors who cover many occupational hazards cannot know about all of the available noise control options without assistance from professionals in acoustics. The ASA needs to develop a method of alerting its members about the specific congressional committees, federal agencies, and activities where acoustical expertise is needed. For the greatest effectiveness, ASA and its Noise Committee should be prepared to take a stand on important noise control issues.
A bivariate model for Arctic undersea noise
Authors: Nagle Samuel M.
Published: October 2005

A bivariate model is developed for the impulsively contaminated noise of the Arctic undersea environment. It is based on one proposed by S. V. Czarnecki [‘‘Nearly Optimal Detection of Signals in Non-Gaussian Noise,’’ Ph.D. thesis, Dept. of EECS, Princeton Univ. (October 1983)] where impulsive and normal background noise regions are treated as coming from two independent Gaussian sources with differing variance. The noise is considered as the output of a switch that toggles between the two noise sources. In this paper, a statistical analysis is conducted on a 10-min time series of Arctic in-water noise data (Fram II) to provide a stochastic description of the real noise data within the framework of such a model. A median filter-based detector is developed to detect the state of the noise source selection switch and partition the time series into the impulsive and normal background regions. Goodness-of-fit tests are used to check the dual source noise distributions against the Gaussian hypothesis. A point process description of the operation of the source selection switch is also derived by statistically analyzing the switch transition inter-arrival times.
Low-frequency ambient noise variation in the Beaufort Sea
Authors: Gardner Susan D. , Meredith Roger W.
Published: October 2005

NRL/SSC conducted Arctic acoustics experiments in the Beaufort Sea as part of ICEX-92 in March and April of 1992. One objective was to collect a long-term time series of low-frequency (less than 50-Hz) acoustic ambient noise with a volumetric array to investigate environmental forcing functions and 3-D noise characteristics. A total of 191 nearly continuous hours of acoustic ambient noise was collected with a vertical array and three horizontal line arrays that were separated approximately 60° in azimuth. A geophone array was also deployed coincident with one of the horizontal line arrays. Meterological data collected included wind speed, wind direction, temperature, and barometric pressure. Oceanographic data included CTD’s and current velocities. Local environmental conditions varied widely during the data collection period. In addition, both ridging and an opening of the ice occurred within 500 ft of the vertical array during data collection. The focus of this presentation is the first step in the analysis of this data set and examines the relationship between ambient noise level fluctuations observed on an individual hydrophone and changes in local air temperature for different time scales. Gradual surface temperature increases and decreases over 10-h time segments occur simultaneous with an increase in the noise fluctuation. Temperature changes during time periods less than 5 h show minimal effect on noise fluctuations. Geophone data agree well with acoustic data in both level and fluctuation. Comparisons of ambient noise with other local forcing functions will be discussed. [This research was supported by ASW Environmental Acoustics Support Program (AEAS).]
Transduction mechanisms
Authors: Busch-Vishniac Ilene J.
Published: October 2005

While acoustical transducers such as microphones and loudspeakers have changed dramatically over the years, the fundamental mechanisms upon which they are based have remained the same. In this tutorial focus is on the underlying principles of electrochemical transduction. The session will begin with a brief presentation of an energetically consistent way to view transducers. Next this approach will be used in describing a variety of transduction mechanisms including, but not limited to, piezoelectricity, electrostriction, magnetostriction, linear magnetic transduction, and piezoresistivity. Advantages and disadvantages of each approach to transduction and examples of transducers using each transduction mechanism will be discussed. Finally, some topics on the frontiers of transduction research, such as solid state sensors, will be touched upon.
Predicting room acoustical behavior with the ODEON computer model
Authors: Naylor Graham , Rindel Jens Holger
Published: October 2005

The computational bases of the ODEON model for room acoustics are described in a companion paper. The model is implemented for general use of a PC. In this paper, various technical features of the program relevant to the acoustical design process are presented. These include interactive visualizations of reflection paths and sequences, mapping of overall energy distributions and of coverage provided by individual reflectors, and minimized recalculation times. Comparisons are made between predicted room acoustical indices and values measured in full-size and model halls, and reasons for discrepancies are discussed. These discrepancies indicate areas in which the computational model has to be improved, and highlight some shortcomings of current room acoustical survey methods. The effects of various calculation parameters (e.g., number of rays, early reflection order) are also briefly considered.
Evaluating the importance of source directivity, frequency, and phase response in the auralization of sound system designs
Authors: Mochimaru Akira
Published: October 2005

Acoustic sources for the sound systems, i.e., loudspeakers have unique and individual characteristics such as amplitude frequency response, phase frequency response, transient response, and directivity. Consideration of these characteristics is as important a part of sound system auralization process as the calculation of precise room responses, such as diffusions and diffractions, in architectural acoustic oriented auralization systems. However, no statistical studies have been made on this subject so far. In this study, the importance and advantage of considering sound source characteristics as a transient response are revealed and a practical impulse response calculation algorithm that is accurate enough and practical for auralization of sound system designs is described.
A modified evaluation of energy parameters in ODEON 1.1 using Sabine’s diffuse energy decay formulas
Authors: Januarsari T. R.
Published: October 2005

The lack of diffuse reflection in a room acoustic computer model ODEON 1.1 [created by Tech. Univ. of Denmark] is considered as one major technical shortcoming. This can lead to very poor estimation of the reverberation behavior of the room whose geometry is itself poorly diffusive. In order to overcome this problem, surfaces are considered to be partially specularly and partially diffusely reflecting, as quantified by absorption coefficient a and diffusion coefficient d, respectively. The diffuse energy, i.e., a proportion d(1−a) of the incident energy, is assumed to be distributed uniformly inside the room and accumulating in an imaginary pool. By using Sabine diffuse energy decay formulas: E(t)=E(t0)exp[−(t−t0)/τE], the diffuse sound energy coming into pool at any time t can be calculated. Thus the total diffuse energy accumulated in the pool at certain time t is added to the nondiffuse energy, and taken into account in evaluation of energy parameters. The prediction of RT and EDT in midfrequencies give better agreement with measured RT and EDT made in rectangular 1:50 model room, than those of origin program. [Research project for Master degree, supervised by Dr. Y. W. Lam.]
Including diffraction effects in image method solutions for sound fields in arbitrarily shaped rooms
Authors: Kovitz Paul S.
Published: October 2005

The image method is often used by computer programs to model sound fields in rooms. Because programs that use the image method ignore the effects of diffraction, the programs fail to model the sound field correctly when a room has an arbitrary shape. A new computer program that attempts to address this limitation has been developed. The program models both geometrical and diffracted components of the sound field by combining the image method with infinite wedge theory. Experimental data are used to evaluate the validity of this new program.
Additional data on low-frequency elastic wave propagation in ice
Authors: Stein Peter J.
Published: October 2005

Current ONR initiatives in ice mechanics research are looking toward using wave propagation in Arctic pack ice as a means to probe the ice mechanical properties. The most robust modes of wave propagation are the low-frequency (<100 Hz) flexural, longitudinal, and horizontally polarized shear waves. Here use is made of multi-sensor triaxial geophone data from the ICEX-1-90 experiment and the March 1992 Allen Bay ice mechanics-acoustics experiment to further analyze these waves under ideal first-year ice conditions. Data will be presented on wave speeds (2750 m/s for longitudinal and 1650 m/s for shear), attenuations, and scattering. Inverting this data to obtain ice mechanical properties such as the moduli, Poisson’s ratio, density, and thickness, will also be looked at. Discussion will address the impact of the nonuniform vertical structure of the ice and the accuracy to which the mechanical properties can be uniquely specified. [Work supported by ONR Arctic Sciences Program.]