bluuebunny/crossref_metadata_2025 huggingface dataset:
New developments in the field of acoustic transducers
Authors: Sessler G. M.
Published: October 2005

New developments in the field of acoustic transducers based on the silicon, fiber-optic, and polymer technologies are reviewed. The silicon transducers are produced on silicon wafers with micromechanic methods utilizing anisotropic etching procedures. Subminiature transducers of this kind, based on the capacitive or piezoelectric principles, were made with membranes of about 1-mm2 area and less than 1-uμm thickness. Their use as “intelligent sensors” with on-chip signal-processing capability is presently under study. Fiber-optic sensors consist of glass fibers and detect modulations of either phase or amplitude of the transmitted light waves, caused by interaction of the sound waves with the fiber. Such transducers have initially been used as hydrophones and accelerometers but are now also under study as microphones. Polymer-electret transducers are finding widespread applications as microphones, earphones, and ultrasonic devices. New developments include the use of electret biasing in silicon transducers and the design of electret-microphone arrays and antennas. Piezoelectric polymer transducers were recently improved by the use of better materials and by innovative poling techniques, such as methods to produce single-film monomorphs and bimorphs.
A new piezoelectric microphone with divided electrodes
Authors: Imai Nobuomi
Published: October 2005

A new type of piezoelectric ceramic microphone is proposed. Its merits are as follows. (1) High output, high efficiency—A high output voltage was obtained by dividing the piezoelectric ceramic electrodes and connecting them in series. The output voltge is proportional to the number of divisions. However, since the impedance is high, an FET circuit is required to decrease output impedance. At the same time, an improvement of the signal-to-noise ratio was also realized. (2) Reduction of diaphragm mechanical impedance—To improve the matching to the impedance of air, a mechanical transformer was introduced. The center of the diaphragm was lightened and its rigidity was increased by combining a dome-type diaphragm and ring-shaped piezoelectric ceramic. This made it easy to control the frequency response. (3) Stability—The diaphragm consists of a Y2O3⋅PSZ ceramic thin film formed into a dome shape and laminated to a ring-shaped ceramic. This structure showed a higher temperature stability and noticeably lower aging change than the conventional flat-type diaphragm. The specifications of the prototype microphone are the following: diameter, 1 in. (23.8 mm), nondirectional; sensitivity, −59 dB/uμbar at FET source output; frequency response, 20 Hz–12.5 kHz −+ 1.5 dB; S/N ratio, 59 dB A-weighted.
Use of thin PVDF film for measuring small single-crystal samples of high temperature superconductors
Authors: Maynard J. D. , Mather J. H. , Brown Stewart , Migliori Albert
Published: October 2005

Although polyvinylidene fluoride (PVDF) piezoelectric film has been adopted in commercial applications for some time, its use in basic research has been less extensive. Recently, there have been found significant advantages in using PVDF to study the ultrasonic properties of the new high-temperature oxide superconductors. In order to probe the anisotropy of the oxide superconductors, it is necessary to study single crystals, but currently available crystals are very small, on the order of the millimeter square and only about 100uμm thick. Measuring the temperature dependence of the ultrasound in such a small sample without having the transducer (or its leads or substrate) intrude on the measurement is a difficult problem that is not readily solved with conventional transducer materials. However, PVDF films as thin as 9 μm are commercially available and easily adapted to small samples and low-temperature operation. Small active areas and leads are produced with metalization patterns on each side of the PVDF film. For resonance measurements, electrical crosstalk across the small sample is processed by frequency modulating the drive and using phase sensitive detection. In our experiment, resonances in ≃ 100-uμm samples are measured with large signal-to-noise ratios. [Work supported by the Office of Naval Research and NSF Grant DMR 8701682.]
Directional microphone systems for teleconferencing
Authors: Elko G. W. , West J. E.
Published: October 2005

Many factors have contributed to historically unrealistic predictions for the growth of audio teleconferencing. Aside from the sociological issues, there exist many acoustic problems that can severely degrade the performance of present technology. A few of these problems are: the effects of reverberation, room noise, feedback, undesired speakers, and echo. At present, the most common solution for some of these problems has been to locate a microphone(s) in close proximity to the desired speaker(s) with gain switching to eliminate feedback problems. While this solution can sometimes be effective, it also introduces some compromises that are easily spotted and are considered annoying by teleconferencing users. The most notable problems are with gain switching and reverberation. These detrimental effects can be reduced by the use of highly directional microphones systems tailored to the problems of teleconferencing. The development of directional microphones and their present use in audio teleconferencing will be reviewed. Some of the highly directional microphone arrays that have been worked with will be described. Finally, comments will be given on how these new directional microphone systems address the problems of teleconferencing in small and large acoustic environments.
On the use of terfenol D in underwater acoustic projectors
Authors: Moffett Mark B. , Linberg Jan F. , Powers James M.
Published: October 2005

Terfenol D, an alloy of iron, terbium, and dysprosium, is a highly magnetostrictive material that can provide significantly more power than lead zirconate titanate (PZT) under field-limited conditions. Field-limiting at resonance, however, requires a mechanical quality factor Qm, less than unity for terfenol D and less than four for PZT. Transducers that are a small fraction of one wavelength in size will have to be elements of a large array in order to achieve the requisite low Qm's. If the Qm is too high, the transducer will be stress-limited, rather than field-limited, and the use of terfenol D is not particularly advantageous. [Work supported by NUSC's IR/IED program and by ONT.]
On left- and right-circularly polarized waves in isotropic noncentrosymmetric elastic media
Authors: Lakhtakia Akhlesh , Varadan Vasundara V. , Varadan Vijay K.
Published: October 2005

Acoustic waves in solids can discriminate between a chiral scatterer and its mirror image. Thus it is possible to construct an acoustically chiral composite medium by embedding chiral microstructures in a host medium. The microstructure size should be large enough compared to the shear wavelength in the matrix medium so that an incident wave can sense its handedness; at the same time, the microstructure size should be small enough that, at least in some frequency range, the composite structure should appear to be effectively chiral. Isotropic composite media with chiral microstructure can be modeled as noncentrosymmetric (hemitropic) micropolar elastic solids, which have been the subject of some recent investigations. The simplest possible constitutive equations have been obtained, and the dispersion equations have been derived and studied. Approximate solutions of the inhomogeneous field equations have also been derived using dyadic algebra. [Work supported by the Research Center for the Engineering of Electronic and Acoustic Materials.]
A study of generalized Lamb waves in solid-state bonded aluminum-steel samples
Authors: Adler Laszlo , deBilly Michel , Quentin Gerard , Talmant Maryline , Nagy Peter B.
Published: October 2005

Wave propagation in the aluminum layer on a steel substrate and the steel layer on an aluminum substrate has been studied. These material combinations correspond to the special case where the transverse velocities are close to each other while the densities and longitudinal velocities are not. Experimental measurements were carried out using two different methods: (i) single transducer broadband, and (ii) double transducer narrow band. Experimentally obtained dispersion curves for the phase velocities were compared to existing theoretical calculations. A method to evaluate the quality of solid-state bond based on the measured dispersion curve is also suggested. [Work supported by D.O.E.]
Scattering-induced error in longitudinal wave velocity measurements
Authors: Tada Hiroki , Fukuoka Hidekazu , Yamasaki Tomohiro
Published: October 2005

The scattering of an elastic longitudinal wave on reflection at a free-plane boundary is studied using the analytical solution for a two-dimensional wave field generated by strip surface stresses. The variation in the scattered field is calculated with various incident angles of the narrow beams and displayed in polar diagrams, which show a wide range of scattered strength. The calculated result reduces to the specular reflection of an infinite plane wave with an increase in the number of beams in the bundle. These results give the basis for estimating the experimental error due to the scattering of the first and second echoes launched by transducers of finite width. The scattering-induced error is well characterized by the ratio of the transducer width to the square root of the specimen thickness, both being normalized by the wavelength. As this ratio increases from zero, the error begins to increase, passes a peak, and then approaches a constant value. To minimize the error, the use of a transducer is suggested for which the nearfield length is at least four times the specimen thickness.
Development of hearing aids without earphones
Authors: Ono H. , Kanzaki J.
Published: October 2005

Inserting earphones in your ear canal can be uncomfortable sometimes. In fact, many people with light and moderate hearing impediments do not wear earphones for this reason, although they know that hearing aids can greatly enhance their hearing. To solve this problem, a new system of hearing aid was developed that will make sounds sound louder in certain areas—around the subject's ears—than in other areas of the room. Three methods for the system were devised. They use: (1) interference of ultrasonic interference, (2) nonlinear principle of parametric speakers, and (3) equipment to accumulate sound reflection. For each method, studies were conducted on: the S/N ratio of output sound pressure to sounds in other areas, energy conversion efficiency, methods to cancel outside noise, effect on human health, and the size and price of the device. All three methods were found to be feasible. Units were built on a trial basis using the three above methods, and are being studied to see if they can actually be used as hearing aids.
Interaction between compression limiting and frequency gain characteristics
Authors: Link H. Cynthia , Cudahy Edward A. , Levitt Harry
Published: October 2005

The interaction between frequency gain characteristics and compression limiting was investigated using an adaptive paired comparison strategy to estimate the optimum post-limiter frequency response for each of three pre-limiter frequency gain characteristics. Frequency-dependent compression limiting paralleling the subject's loudness discomfort level (LDL) curve was used. Stimulus intensity was adjusted to provide three levels of compression limiting. Results for both preference and intelligibility judgments with continuous discourse in quiet showed that most subjects tended to compensate for manipulations of the pre-compression filters with adjustments in the post-compression filters. The amount of compression had only a secondary effect on filter selection. [Research supported by NIDRR.]
Error analysis of cochlear implant consonant distributions
Authors: Wasserman Gerald S. , Miyamoto Richard T.
Published: October 2005

Consonant discrimination in a two-alternative, forced-choice design was measured in adult- and juvenile-onset cochlear implant patients under control (3M-House) and receptor-coded conditions [cf. J. Acoust. Soc. Am. Suppl. 1 82, S71 (1987)]. Errors were not symmetric but dependent on which alternative of a pair of consonants had been spoken. Errors conserved phonemic identity for adult- but not for juvenile-onset patients. A two-dimensional (control versus receptor coding) coincidence filtration of adult-onset errors implicated second-degree regulation of performance by the various articulatory features of speech. This implication was tested with a regression analysis: it demonstrated a reliable influence of certain articulatory features, particularly of voicing and plosion, in both conditions. A coding-dependent shift of articulation influence was found: Voicing became a more reliable cue with receptor coding, manner cues changed subtly between conditions, and place became a reliable cue with receptor coding. [Work supported by NSF.]
Predictors of TTS after pure-tone exposure in the cat
Authors: Wiederhold Michael L. , De La Cruz J. Luis , Metzman Louis , Prihoda Thomas J.
Published: October 2005

Anesthetized cats were exposed to 4-kHz pure tones, of varying level and duration. The N1 auditory-nerve responses to filtered clicks, at 2, 4, 6, 8, 10, and 15 kHz, as well as 2f1 − f2 distortion product (DP) signals in the ear canal, were recorded before and after exposure. The f1, f2 pairs were 4.0 and 5.2 kHz for all animals and, additionally, 1.6 and 2.1 kHz and 4.6 and 6.0 kHz in a subset of animals. In all cases, L1 = L2 + 10 dB. Multiple polynomial regression analysis, relating pre-exposure 10-μV N1 thresholds at 4 and 6 kHz, −10-dB SPL DP thresholds for 4.0- and 5.2- and 4.6- and 6.0-kHz primaries and noise dose (total energy) to 6-kHz N1 threshold shift (TS) and DP TS (4.0- and 5.2-kHz primaries), as outcomes. The TS for both N1's and DPs displayed considerable variability between animals, even with the same exposure. Pre-exposure 4- and 6-kHz thresholds were the best predictors of 6-kHz TS (r2 = 0.57 and 0.58, respectively, p = 0.0001) and 6-kHz TS was the outcome that could be predicted with the most certainty. Addition of DP threshold did slightly increase the predictive ability of the model. Pre-exposure N1 threshold only weakly predicted DP TS. The DP TS assessed 6-kHz N1 TS weakly (r2 = 0.27) but significantly (p = 0.014). The poorer ability of DP threshold and DP TS to predict N1, TS, compared to pre-exposure N1 thresholds, is consistent with the variability between animals in DP levels, which are susceptible to abnormalities in forward conduction, sensory function, and reverse conduction of DP signals into the ear canal. [Work supported by Veterans Administration Medical Research Funds.]
The response of a hot film anemometry system and the mechanosensory lateral line of a teleost fish to the local flow field of a dipolar source
Authors: Coombs Sheryl , Janssen John
Published: October 2005

A hot film anemometry system (TSI, inc.) was evaluated for its potential use in characterizing lateral line stimuli by measuring its response to a sinusoidally vibrating sphere over a wide range of frequencies, intensities, and distances from the sphere. The amplitude response of the anemometer probe to signals along the axis of vibration was found to be linear over a 50-dB range for frequencies from 10–200 Hz and responses to displacement levels as low as 10−9 m were recorded. The measured attenuation of the signal with distance was also linear over this frequency range out to distances of six times the radius (= 3 mm) of the sphere, and followed the predicted falloff rate, 1/r3 (where r = distance from sphere center), for a dipolar source [Harris and van Bergeijk, J. Acoust. Soc. Am. 34, 1831 (1962)]. Behavioral measures of lateral line sensitivity in a benthic fish, the mottled sculpin (Cottus bairdi), also attenuated at the rate of 1/r3 for a wide range of stimulus frequencies. This attenuation rate can be predicted for benthic fish which, because they are coupled to the substrate, do not move in the flow field, but not for midwater fish that are neutrally buoyant and coupled to the surrounding water. [Work supported by NIH].
Midline and lateral field sound localization by the grasshopper mouse, Onychomus leucogaster
Authors: Kelly Jack B. , Furlonger Caren L.
Published: October 2005

Comparative studies of sound localization have placed almost exclusive emphasis on obtaining minimum audible angles for sources positioned symmetrically around midline. Little attention has been paid to the ability of animals to localize sounds within the lateral fields and reports of minimum audible angles for off-midline positions are rare. A recent study by Kavanagh and Kelly [Behar. Neurosci. 100, 200–205 (1986)] indicates that the albino rat has great difficulty localizing a brief acoustic stimulus in the lateral fields, a finding that is unexpected from estimates of midline acuity. The present study was undertaken to determine whether other small mammals might experience similar difficulty. Minimum audible angles were obtained for 0, +60, and −60 deg azimuth using a broad-spectrum single click in a two-choice spatial task. The minimum audible angles as defined by 75% performance levels were 28 deg for midline and 48.5 deg for the lateral fields indicating that the grasshopper mouse does have difficulty with lateral field localization but not to the same extent as the albino rat. [Work supported by NSERC.]
Measures of laryngeal adduction
Authors: Scherer Ronald C. , Vail Vernon J.
Published: October 2005

The degree of closeness of the arytenoid cartilages (laryngeal adduction) plays an important role in vocal function and quality. In this paper, adduction for steady vowels was varied between voiced qualities of breathy (greater abduction) to normal to constricted (greater adduction). The superior view of the larynx of various subjects was videotaped and dimensions of laryngeal adduction were measured. The measurements were compared with values of the abduction quotient [1. R. Titze, J. Acoust. Soc. Am. 75, 570–580 (1984)] obtained from simultaneous recordings of the electroglottograph signal and with a measure of electroglottograph waveform width. The width measure strongly correlates with the abduction quotient. Results suggest that the adduction measures may be useful for clinical and research purposes. [Work supported by NIH.]
Physiologic factors in vocal vibrato
Authors: Shipp Thomas , Doherty E. Thomas , Haglund Stig
Published: October 2005

Vocal vibrato when produced on a sustained vowel with constant subglottal air pressure is made up principally of fundamental frequency oscillations about the target pitch. This type of phonation was studied in two professional and one amateur singer, while EMG activity was sampled from their cricothyroid muscle (CT) unilaterally. Singers initiated phonation at a designated frequency without vibrato and then changed to their customary vibrato production. Coincident with the onset of vibrato, the EMG activity from the CT changed from a relatively stable interference pattern to one of quasiperiodic bursts and attenuation. Bursts immediately preceded initiation of upward F0 for the vibrato wave while attenuation preceded downward F0 movement. Further, the average integrated EMG value over one vibrato cycle equaled the EMG level for straight tone production at the same frequency. These data provide evidence for a metering system of neuromuscular discharges that equate CT activity and F0 mean whether during production of straight tone or vibrato oscillations.
An overview of array processing methods for ω-k analysis of space-time signal fields
Authors: Baggeroer Arthur B.
Published: October 2005

Signals from an array of sensors can be used to estimate the frequency-wavenumber content of a signal field using several methods. The array geometry has a significant impact upon the signal processing methods used. In those applications where the arrays have a lattice spacing, 2-D or 3-D extensions of Fourier methods can readily be used; however, when the array has few sensors and/or sparse and irregular spacing, alternative algorithms must be used. These include approaches based upon minimum variance filters (maximum likelihood), prediction-error filters (maximum entropy), and eigenvector (MUSIC) decompositions. Many structural acoustics experiments involve broadband, transient signals, so the time variation of the wavenumber content of the field becomes important, e.g., when group as well as phase speeds are desired. There are a number of methods for transient analysis that are commonly referred to as velocity, or slowness, time spectra. These also must be tailored to the array geometry. This presentation will give an overview of the methods used for ω-k analysis with applications drawn from structural, borehole, and underwater acoustics.
An underwater acoustic imaging method using cross-fan beam scanning
Authors: Kaihoh Ieharu , Hayakawa Hisami , Osanai Masanori
Published: October 2005

A real-time underwater acoustic imaging method named cross-fan beam scanning has been developed by OKI Electric Co., Ltd. In this method, acoustic projector elements are arranged vertically, and hydrophone elements are arranged horizontally to form a cross-linear array. That transmitting array generates thin horizontal fan beams, and the receiving array generates multi-thin-fan preformed vertical beams. Total beam patterns are obtained as the product of the transmission and reception beam patterns, so that narrow pencil beams are generated at the intersection of the two beams. Transmission and reception beams are electrically scanned, respectively, and the resulting pencil beams can be pointed at in any direction in a moment. Using this method, several types of imaging systems were completed. These are installed in submersibles, surveying ships, and work vessels such as the “Shinkai-6500” deep-sea manned submersible of the Japan Marine Science and Technology Center and the “Marcas-2500” deep-sea ROV of KDD, etc. In this paper, the imaging principle, the sonar system design, and the characteristics of typical systems are described and the imaging results are shown.
Wavenumber-frequency calibration for planar arrays
Authors: Trivett D. H. , Luker L. D. , Petrie S. , Van Buren A. L.
Published: October 2005

Wavenumber-frequency calibration of planar receiving arrays requires the ability to generate homogeneous, single wavenumber pressure fields over the surface of the array. When the wavenumber-frequency region of interest is evanescent, transmitting arrays previously designed to generate such fields have been found to generate fields contaminated with harmonics, acoustic wavenumbers, and nonacoustic wavenumbers from the excitation of antisymmetric Lamb waves. Two transducers that greatly reduce contamination have recently been constructed using sheets of PVDF with 20 independent rectangular electrode stripes. The stripes are driven with shading coefficients generated by a simple point source numerical algorithm and are found to be capable of generating homogeneous, single wavenumber, evanescent pressure fields over a specified region. The two arrays differ in their method of eliminating contamination due to the excitation of antisymmetric Lamb waves. One array shifts the phase velocity of the Lamb wave out of the region of interest by bonding the PVDF directly to a thick plate of Lexan. The second array decouples the PVDF laterally by the use of slicing along the electrode stripes and plotting in a heavily damped elastomeric material. Measured pressure fields and phase velocities of both arrays are compared with numerical calculations. [Work partially supported by ONT.]
A wavenumber domain analysis of the coupling of a structural mode and flow turbulence
Authors: Hwang Y. F. , Maidanik G.
Published: October 2005

Previous studies on the coupling of a structural mode and the pressure field induced by a turbulent boundary layer have concentrated on the determination of the relative contributions of two regions of the wavenumber domain; the high-wavenumber region at and near hydrodynamic coincidence and the low-wavenumber region at and near the structural free wavenumber. The corresponding contribution to the coupling by the intermediate-wavenumber region that lies between the high- and low-wavenumber regions has not received proper attention. In this paper, formulas to estimate the contributions to the coupling by the three wavenumber regions are derived, and numerical results are evaluated and compared. It is found that situations exist in which the contribution by the intermediate-wavenumber region may be significant. [Work supported by ONR.]
Efficient computation of ideal starting fields for parabolic equation models
Authors: Robinson E. Richard , Wood David H.
Published: October 2005

When one replaces the Helmholtz equation by the related parabolic equation, the resulting gain is the relative numerical ease of solving the parabolic equation using a marching type algorithm. However, one is left with the problem of providing the initial data—or the starting field for the PE model. Although it is well known that the normal mode starter is the corrected initial data, it is not widely used because of the expense involved in the compuation. In this approach, however, the idea that one need not compute the normal modes individually to obtain the correct starting field is exploited. If one considers the function represented by a weighted sum of the normal modes, then it is found that the correct starting field can be obtained by computing the −14 power of the matrix generated from the FFT of the index of refraction. This result is derived and some examples of the starting fields are presented and compared to starters computed or approximated in other ways. Further, the effects on PE model outputs using the various starters are demonstrated.
Weighted-Gaussian-quadrature-generated irrational functions for ray trajectories for range-independent and range-dependent problems
Authors: Floyd Edward R.
Published: October 2005

A parametric description of ray trajectories in terms of irrational functions was developed. These irrational functions are generated by applying weighted-Gaussian quadratures (WGQ) to a parametric Hamilton-Jacobi representation of the ray trajectory. The irrational function may be developed in principle to any order as it is consistent with the order of our weighted-Gaussian quadrature. The Hamilton-Jacobi transformed canonical variables are constants for the range-independent problem but are functions of range for the range-dependent problem. The range dependence of the transformed canonical variables has been developed by nonadiabatic range-dependent canonical perturbation theory. The irrational function description of the ray facilitates a description of the perturbing Hamiltonian in terms of only range and the transformed canonical variables. The perturbation expansion of the transformed canonical variables is structured to be consistent with the expected WGQ remainder. This perturbation technique is applicable to cases whose unperturbed Hamiltonians cannot be integrated in closed form.
Complex source pulsed beams: New test pulses for transient acoustic propagation and diffraction modeling
Authors: Heyman E. , Steinberg B. Z. , Felsen L. B.
Published: October 2005

Complex source pulsed beams (CSPB) are transient waveforms generated when the space coordinates and initiation time of a pulsed line source (two dimensional) or point source (three dimensional) are assigned complex values. They generalize to the time domain the time-harmonic, complex-source-point Gaussian beams. A CSPB is described by the analytic signal obtained from analytic continuation of the conventional impulsive time-dependent, free-space Green's function to the domain of the complex source parameters that control the spatial and temporal widths of the pulsed beam. Numerical examples illustrate the CSPB shapes obtained for various choices. Generalized CSPB fields can be constructed by convolving the CSPB with various time functions. The general theory of the CSPB is discussed. It is also shown how to apply the CSPB as the excitation of a propagation or diffraction environment when the complex space-time source coordinate substitution is performed on the conventional space-time Green's function for that environment. This yields new formulations for transient propagation and diffraction. Examples include a two-fluid medium separated by a plane interface, and diffraction by a knife edge. [Work supported by ONR.]
A VLF propagation experiment off the coast of Oregon: Measurements and numerical predictions
Authors: Fisher C. A. , Ali Hassan B. , Authement Mona
Published: October 2005

The Naval Research and Development Activity (NORDA) recently conducted a very low-frequency (VLF) acoustic experiment in a sloping bottom environment off the coast of Oregon. A 16-element vertical hydrophone array was deployed in water depths of 200 and 400 m. An upslope and two cross slope explosive shot lines were completed. In addition, an upslope cw (15 Hz) tow was recorded. This paper uses the results of this experiment to investigate the importance of bottom shear and bathymetric variation on energy partitioning between water and ground paths. The measured data are compared with predictions from SAFARI, a range-independent model that allows conversion to shear energy in the bottom, and PE, an acoustic model that allows variable bathymetry. Two different PE codes are used, viz., IFDPE and a PE pulse code recently developed at NORDA (M. Collins), which allows for subbottom structure that is not necessarily parallel to the ocean bottom. Measured cw propagation loss and explosive shot record sections are compared with predicted results from both SAFARI and PE.
A generalized canonical sound-speed model
Authors: Daubin Scott C. , Nghiem-Phu Lan , Tappert Frederick D.
Published: October 2005

A generalized canonical sound-speed (GENCASS) numerical environmental model has been developed to support range-dependent underwater acoustical propagation models, especially the PE/SSF model. The GENCASS model provides an interface between the environmental data base and acoustical model; it could guide and improve the cost effectiveness of the processes of environmental data acquisition, processing, storage, and access. It extends the usefulness of Munk's canonical model to include conditions where no subsurface axis exists, as in the arctic and subarctic, and provides for such common phenomena as mixed layers, fronts, eddies, and the double minima found in the region influenced by the Mediterranean outflow. It provides a natural parametric hierarchy for organizing environmental data, based on phenomenological time scales, ranging from climatological to seasonal to diurnal. In temperate regions, four parameters are sufficient to define the model: scale depth, bottom temperature, extrapolated surface temperature, and either actual surface temperature or mixed layer depth, which are functionally related. The GENCASS model introduces a surface thermal layer depth to account for surface superheating that may occur in tropical waters. A mixing function is introduced to account for the transition through oceanographic fronts, across eddies, and through the double minima profile. A companion paper will use the GENCASS model to support PESOGEN-II illustrative runs.
An inquiry into noise intrusion in naturally ventilated tropical school buildings
Authors: Allen Barbara
Published: October 2005

Many schools in tropical areas are naturally ventilated to save on costs of air conditioning. The inherent problem with this method of cooling is noise intrusion from adjacent areas, rendering the classrooms marginal teaching environments. Four naturally ventilated problem classroom buildings on the University of Hawaii campus are studied. The noise problems were identified as to source, location, SPL, and frequency. Reverberation times were measured for the classrooms at the various frequencies. Construction documents were used to verify the various building materials and that field transmission loss teats were conducted. Theoretical retrofit solutions were proposed for each classroom building. Solutions included site alterations, building fenestration additions, and interior space modifications. This study is the initial phase of the actual physical modeling that will take place next year in order to test our theoretical solutions.
Random incidence sound transmission through foam-lined panels
Authors: Shiau N.-M. , Bolton I. S. , Ufford D. A.
Published: October 2005

Recent measurements of the sound transmission loss of aluminum panels lined with polyurethane noise control foam are reported. The measurements were conducted using an intensity probe to measure the sound power transmitted through panels mounted in the wall of a reverberation room in which a diffuse sound field was generated. Tests were conducted using four single-panel configurations: i.e., a single 1.27-mm aluminum panel and a 27-mm foam layer that was either bonded directly to one side or the other of the panel with glue or was separated from the panel by small spacers (thus creating a thin air gap between the panel and the foam). It was found that bonding the foam to the panel lowered the coincidence frequency from approximately 10 to 2 kHz; below this frequency, however, performance is improved relative to the unbonded treatment. Four double-panel configurations have also been tested: i.e., with the foam mounted directly to one or the other of the interior panel faces or separated from it by a small distance using spacers. Effects similar to those described above have been observed. It will also be shown that these effects are well predicted by a recent theory of two-dimensional wave propagation in elastic porous material [J. S. Bolton and N.-M. Shiau, AIAA Paper AIAA-87-2660 presented at the 11th Aeroacoustics Conference, San Jose, October 1987].
Final lengthening and the prosodic hierarchy
Authors: Hayes Bruce
Published: October 2005

Segments undergo phonetic lengthening both utterance-finally and in certain medial contexts, characterized informally as “word-final” or “phrase-final.” No complete account exists of what these contexts are, or how they vary in the degree of lengthening induced. In phonology, prosodic hierarchy theory (Selkirk, 1980) posits that syntactic structure is reparsed into a hierarchy of nested levels of phonological phrasing. The theory is based on phonological rules that apply only when all segments involved occur within a single phrase of a particular size. The theory suggests a general account of final lengthening: The higher the level of a phrase on the prosodic hierarchy, the more final lengthening it receives. This hypothesis is compatible with the final lengthening rules proposed by Allen et al. (1987). The experiment described here used the method of Beckman and Edwards (forthcoming) to test the hypothesis further. Sentences were recorded in which the words hate, incompetence, and hating competence were divided across clitic group, phonological phrase, and intonational phrase boundaries. The prediction is that hate and hating should show increased final lengthening across the three contexts. Pilot results agree roughly with the predictions of the theory.
Acoustic-phonetic correlates of stress shift
Authors: Shattuck-Hufnagel Stefanie
Published: October 2005

Many speakers of American English exhibit “stress shift,” in which the lexical prominence of a polysyllabic word seems to shift to an earlier syllable, as when “thirTEEN” becomes “THIRteen” in “THIRteen MEN,” or “MissisSIPpi” becomes “MISsissippi MUD.” Fundamental frequency and duration measurements suggest that this is a phrase-level phenomenon that arises from the confluence of two separate events: (a) The pitch accent occurs not on the target Word, but on a different word of the phrase (here “MEN” and “MUD”); and (b) another phrasally based pitch rise occurs on the earlier syllable of the target word (here “THIR-” and “MIS-”). Three lines of evidence support this account: (1) The first rise can occur even earlier, i.e., on a preceding word, suggesting a domain larger than the individual lexical item; (2) under certain conditions of phrasal prosody, for the same word string, the pitch accent returns to the location of the lexically stressed syllable of the target word, showing that the “shift” does not result simply from the lexical stress patterns of adjacent words; and (3) the two types of pitch excursion can have different characteristics, indicating that the early rise and the pitch accent are separate phenomena. These observations are consistent with the hypothesis that pitch marking occurs on lexically stressed syllables when phrasal prosody requires it, but not otherwise.
Word structure and accentuation in Japanese—Is Japanese basic accent the antepenultimate type?
Authors: Sato Hirokazu
Published: October 2005

It has been reported that the accent nucleus of a Japanese word tends to be located on the antepenultimate mora, i.e., the third mora counted from the end of the word (henceforth, the antepenultimate type). This tendency of the accent pattern of Japanese has been confirmed through various statistical analyses [e.g., S. Hashimoto, Trans. Inst. Electron. Commun. Eng. Jpn. 56-D, 654–661 (1973)]. In this paper, the relationship between word structure and accent pattern has been investigated using about 50 000 headwords in the Japanese Accent Dictionary to explain why the antepenultimate type appears to be the most frequent accent pattern in Japanese. The results show that this accent type mainly originates from compound accentuation in (full word + full word) and (full word + affix) concatenations, rather than being an intrinsic accent type of the Japanese language. Further study on the intrinsic accent of basic Japanese words of four morae or less has been conducted. The results will be reported according to the origin of the analyzed words, including original Japanese, Sino-Japanese, and loan words (from western languages).
The influence of higher level linguistic information on production of duration and pitch patterns at syntactic boundaries
Authors: Beach Cheryl M.
Published: October 2005

Syntactic parsing strategies like “minimal attachment” have mainly been studied for written language. However, there is recent interest in whether parsing strategies are used for speech. An alternative view is that, because speech contains acoustic patterns that covary with structure, and these influence listeners' syntactic interpretations, acoustic patterns can indicate structure, and so strategies are unnecessary. A critical assumption of the latter view remains to be tested: Speakers reliably produce acoustic correlates of structure for minimal and nonminimal attachment sentences. The present study investigated this, comparing productions of minimal and nonminimal attachment sentences. Longer duration and more extreme pitch fall-rise were expected for a sentence containing a major syntactic boundary in the critical region (i.e., nonminimal attachment). Surprisingly, phrase-final lengthening did not appear; duration for the syntactic boundary condition was shorter. Additional experiments suggest why. When subjects assign sentence-focus-stress to material in the critical region of a no-boundary sentence, stress is represented by increased duration or pitch rise. Thus both syntactic and nonsyntactic linguistic information influence the form of the acoustic patterns produced, and determine whether the expected differences are observable across sentences. Implications for parsing models and for investigations of speech production and perception will be discussed.
Finite-amplitude propagation in lossless and absorptive media
Authors: Reilly Clarence R. , Parker Kevin J.
Published: October 2005

The propagation of finite-amplitude waves in distilled water and an absorptive fluid media with acoustic characteristics similar to tissue was investigated. Axial and focal beampatterns of linear and quasilinear waves were obtained from lens focused sources of 1.75, 2.25, 2.94, and 3.38 MHz using a PYDF needle-type hydrophone. Experimental beampatterns were compared to spherically converging and focused Gaussian beam theories. The shock parameter at the focus predicted from Gaussian theory was in general agreement with the estimate made from the relative strengths of the first four harmonics to the fundamental. Apodization provided by the lens reduced, but did not eliminate, the nearfield maxima, minima, and sidelobes associated with a piston source. Additional sidelobes predicted from the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation were evident in the harmonic beampatterns. Harmonic focal beamwidths decreased as n−1/2 for the lower source frequencies, in agreement with theory. Beamwidths were generally more narrow in the absorptive media than in the water. The second harmonic peak location on-axis was distal to the fundamental, although the difference was small for higher source frequencies and propagation in the absorptive media. Higher harmonics had sharper axial focal dimensions, but the position of the axial peak was dependent on the trade-off between propagation growth and decay caused by attenuation. The extension of the results to propagation in tissue is noted.
The dynamics of a music education facility design team—The role of acoustical consultant
Authors: Paoletti Dennis A.
Published: October 2005

The design of facilities for music performance, rehearsal, and education is a complex task. Some of the major aspects of realizing such facilities include: Teaming, marketing, negotiating contracts, establishing criteria, client/user interface, technical acoustical analysis and design, aesthetics, consulting, compromise, budgeting, construction/installation, contractor interface, acoustical measurements, acceptance, and evaluation of user and audience satisfaction. This paper will discuss the prominent role of the acoustical consultant in the process of designing facilities for music performance, rehearsal, and education.
The acoustics of small rooms for music practice and teaching
Authors: Klepper David L.
Published: October 2005

At best, the small rooms typical for music teaching and practice are unnatural environments for music production. Given the usual constraints of budget and practicality, a small room cannot be made to approximate the acoustics of a fine concert hall. If all normal modes are suppressed completely by sound-absorbing treatment, the room will be unnaturally dead or anechoic, and will be disliked by students and instructors. Yet, if normal modes are not controlled and the small room left “live,” it will not sound like a normal concert hall but be “boxy,” with a very uneven frequency response, and will be equally disliked. Compromise solutions involving fixed treatment on one wall or two adjacent walls, or adjustable treatment, with varying degrees of room irregularity and splaying, which have provided satisfaction in music teaching buildings, will be discussed. Organ practice rooms pose a separate problem, and solutions involving no applied sound-absorbing treatment, but considerable splaying or irregularities in ceiling and wall surfaces appear best. Some discussion of sound isolation will be presented.
Structural intensity measurement techniques for single and multiple sources
Authors: Wagstaff Peter R. , Bouizem Boudjema , Henrio Jean-Claude
Published: October 2005

The information available for power flow measurements may be used to determine the transmission paths of vibration sources. In multiple source situations, direct measurements of structural intensity do not give information on the contribution of each source. Reference signals associated with each source may be used to condition the spectra obtained at the measurement point to provide an estimate of the power flow due to each input. This technique has already been successfully applied to acoustic measurements. Results are presented using the direct method and these “selective techniques” for measurements using two, three, and four accelerometers, and for single and multiple inputs. The structure used for these experiments was a lightly damped bar and the results, using different types of reference signal and various estimators for the source contributions, illustrate the problems and the advantages of such methods in structural intensity measurements.
Resonant excitation of interface waves on a compliant coating in the presence of a fluid flow
Authors: Talmant Maryline , Bao Xiao-Ling , Überall H. , Madigosky W.
Published: October 2005

The stability of interface waves on a compliant coating, attached to a rigid substrate and exposed to a laminar or turbulent fluid flow, has been the subject of several theoretical studies, and of experimental investigations in which the onset and growth of instability waves was determined. Solutions of the characteristic equation of the problem have been obtained, which furnish dispersion curves and stability information for the interface waves, assuming a compressible fluid in order to attain the correct static limit. It has been shown that the excitation of these interface waves can occur in a resonant fashion; using this approach, an accurate experimental determination of the dispersion curves, the onset of instability, and the growth properties of interface waves will be possible.
Modeling of transient vibration envelopes using statistical energy analysis techniques
Authors: Lai Ming-Lai , Soom Andres
Published: October 2005

The modeling, by the statistical energy analysis (SEA) method, of transient vibration envelopes of coupled systems is investigated. The relation between the time-varying energy transferred between two coupled subsystems and time-varying energies of the individual subsystem is studied numerically and experimentally. These studies indicate that time-varying energy transmitted between two subsystems can be related to the subsystem energies by an appparent time-varying coupling loss factor. It is shown that the apparent coupling loss factor approaches the asymptotic (or steady-state) coupling loss factor as response energies and transferred energies are integrated over progressively larger times. Both the apparent time-varying coupling loss factor and the asymptotic coupling loss factor, determined experimentally, are used in energy balance equations to predict the time-varying vibration envelopes of a system of two point-coupled plates and the results are compared. Although overall response predictions are similar, considerable differences are noted in individual frequency bands
A nonlinear theory for high-frequency vibrations of piezoelectric crystal rods
Authors: Dökmeci M. Cengiz
Published: October 2005

This paper is addressed to a systematic derivation of a hierarchy of one-dimensional theories for the motions of crystal rods in view of the author's review article [Shock Vib. Dig. 20(2), 3–20 (1988)]. The nonlinear theories are derived using a unified variational principle [IEEE UFFC, 35(6) (November 1988)] together with the trigonometric series expansions of the field quantities [cf. Int. J. Solids Structures 10(4), 401–409 (1974)]. All the mechanical and electrical effects and the material nonlinearity are taken into account. The resulting equations govern all the extensional, thickness, flexural, torsional, and coupled motions of crystal rods. By a proper truncation of the series expansions, special motions and material of crystal rods are considered. Also, the fully linearized equations of crystal rods are examined. The sufficient boundary and initial conditions are enumerated so as to ensure the uniqueness in solutions of the linearized rod equations. [Work supported by U.S. Army through its European Research Office.]