bluuebunny/crossref_metadata_2025 huggingface dataset:
Length in Lingua
Authors: Browman Catherine P.
Published: October 2005

Lingua is a program used for synthesizing speech from stored LPC-encoded demisyllables using rules to modify the duration, as well as other aspects, of the stored speech [C. P. Browman, ICASSP 80 Proceedings, 561–564 (1980)]. The original duration rules simply compressed nonphrase-final demisyllables a certain amount, depending on their stress level. The present duration rules, while still quite simple, are based on a different approach in which a variety of factors independently interact to produce the final durations of the subportions of the demisyllables. The factors include binary representation of stress (stress/unstress), binary representation of within-phrase position (final/nonfinal), and a variable factor based on the number of syllables in a set unit. The most recent output from Lingua, using the new rules, will be demonstrated.
Scanning laser acoustic microscopy: A new tool for nondestructive testing
Authors: Yuhas D. E. , Kessler L. W.
Published: October 2005

Acoustic microscopy is an advanced form of ultrasonic imaging in which the operating frequency is extended out to several hundred megahertz (compared with conventional ultrasonic nondestructive testing operating in the range, 1–10 MHz). The higher frequencies make it possible to achieve very high resolution and to interrogate samples for much smaller size defects than were heretofore possible. In addition, samples only a few millimeters in overall size which are not amenable to conventional nondestructive testing techniques may now be inspected. A significant contributor to the practicality of acoustic microscopy is the employment of a focused laser beam which acts as a small point-to-point ultrasonic sensor (receiving transducer). The laser scans the area of a sample at the rate of 30 images per second where each image consists of 40 000 image points. The subject of this presentation will be a discussion of applications of acoustic microscopy and, in particular, results obtained on a commercially available Scanning Laser Acoustic Microscope (SLAM) in the area of nondestructive testing of metals and ceramic materials.
Modes of vibration and modal coupling in a tamtam
Authors: Rossing Thomas D. , Fletcher N. H.
Published: October 2005

When a large tamtam is struck near its center with a heavy padded mallet, the initial deep sound slowly gives way to a delayed sound of shimmering overtones due to high-frequency modes excited by nonlinear coupling to the modes of low frequency. Although the exact nature of this coupling is not known at the present time, it can be described by a semi-quantitative theory which is consistent with experimental data observations. Coupling between two modes of high and low axial symmetry appears to depend upon one or more rings of hammered bumps. Modes of low frequency have decay times as long as 18 s, whereas modes of high frequency decay more rapidly. [Work supported by the U.S.-Australia Cooperative Science Program and by the Australian Grants Committee.]
The nonlinear vibrations of the spring doorstop
Authors: Hartmann W. M.
Published: October 2005

The sonorous twang of the spring doorstop is known and beloved throughout the United States. The waveform consists of a series of impulses of partly random character with significant spectral energy up to 8 kHz. The inverse of the impulse spacing is the fundamental frequency and the waveform exhibits well-developed harmonics at least up to the 20th. Two polarizations of spring vibrations may be excited, but there is a preferred orientation. As the doorstop vibration decays the polarization rotates into the preferred orientation. The fundamental frequency rises by more than an octave (16 to 40 Hz is typical). The fundamental frequency increases linearly with the number of cycles therefore it increases exponentially with time. Stroboscopic observation reveals no indication of wave motion along the spring axis. Therefore it is possible to model the system as two coupled, damped oscillators. The nonlinearity presumably arises from the compression of the spring, which produces a force discontinuity at the origin. Numerical solution of the coupled nonlinear differential equations reproduces most of the features of the spring vibrations, but as of this writing the computed frequency increase with increasing cycle number is not linear, as observed experimentally, but has positive curvature.
Geometric acoustics and coherence propagation
Authors: Berman David H. , McCoy John J.
Published: October 2005

The mutual coherence function of a deterministic acoustic field obeying a parabolic equation will be expressed in terms of Fourier representations of the Green functions for the field. In the short wave limit, these representations allow for a uniform treatment of the field near various real space caustics by circumventing apparent singularities. We use the Fourier representation of the Green function to compute, near a caustic, the intensity arising from an extended source and the mutual coherence function arising from a point source. We will show that the asymptotic Green function expression for the coherence function contains interference effects from separated ray paths that are not contained in local radiative transport equations for the coherence function.
Model of a central lateralization processor—Quantitative evaluation
Authors: Blauert Jens , Lindemann Werner , Gruber Klaus
Published: October 2005

It is established that the hearing system interprets interaural arrival time differences as well as interaural level differences when forming the lateral position of auditory events. Models of binaural signal processing have been constructed which perform the evaluation of arrival time differences and level differences either by means of two separate stages of processing (time difference processor plus level difference processor) or by one single stage which can handle time differences as well as level differences. The present paper deals with a model of the latter kind which has previously been proposed by the first author [Proceedings of the 5th International Congress of Hearing, edited by v. d. Brink and Bilsen (Delft U. P., Delft, 1980), pp. 421–424]. Examples of a quantitative evaluation of the model with respect to psychoacoustical data on lateralization and lateralization blur will be reported. Further implications of the model will be discussed.
SEA equivalences between large platelike systems and their subparts
Authors: Timmerman Nancy S.
Published: October 2005

A procedure was developed to equate the properties of a large system, which is composed of a number of plates connected to each other in a variety of ways, with the properties of the smaller plates for use in Statistical Energy Analysis (SEA) modeling. Each small subsystem is a single plate, which can be characterized by a uniform thickness, an area, a material, and some internal losses. Each connection between systems is defined by a junction, with a length, a number of systems connected at that junction, and thicknesses of each system connected at that junction. Equivalents thicknesses, areas, loss factors, and junction lengths were determined for the larger composite system. The analysis was extended to the case where two composite systems are connected to each other.
Some perceptual cues to syntax: Palatalization and alveolar flapping
Authors: Scott Donia R. , Cutler Anne
Published: October 2005

The application of certain phonological rules of American (but not British) English is inhibited across a major syntactic boundary, e.g., palatalization of alveolar obstruents in the environment of a following palatal vowel [Cooper, Egido, and Paccia, J. Exptl. Psychol. (1978)], and flapping of intervocalic alveolar stops [Egido and Cooper, J. Phonet. (1979)]. We report an experiment testing whether listeners can use the presence or absence of palatalization and flapping to parse syntactically ambiguous sentences (e.g., “The last time we met Ann was horrible”). Twelve such sentences were LPC analyzed and resynthesized with a “neutral” pitch contour; flapped and palatalized segments were also cross-spliced with their nonflapped and nonpalatalized counterparts. Subjects were asked to match each resulting utterance to one of two possible syntactic structures. For native speakers of American English, both flapping and palatalization proved reliable perceptual cues to the absence of a major syntactic boundary. On the other hand, neither feature was effective for British English speakers. Our results suggest that for such contrasts to be of use in speech perception, they must be present in the listener's own speech.
Guitars: Steady state and transient response
Authors: Firth I. M.
Published: October 2005

Measurements of input admittance confirm that the guitar can be considered as a bass-reflex enclosure with flexible sides. The effect of this is to increase the sound output without distortion below the first resonance of the top plate. The proposed equivalent circuit will be reviewed. New measurements on plucked notes using a digital analyzer show that the onset of sound contains two distinct parts. The main steady state resonances are shock excited at the beginning of the pluck, grow, and decay within the first few milliseconds of the onset. Simultaneously the harmonics of the string grow and remain as the sustaining vibration of the tone after the steady state resonances have died away. It appears that every played note of the guitar contains at its beginning sound representative of the steady state response which contains information about the type of instrument being sounded and its quality, and this is followed by the sustaining harmonics of the string. Experiments with the violin, cello, and harp show this new effect to occur also in these instruments.
An acoustic technique for measurement of electric fields inside dielectrics
Authors: Migliori A.
Published: October 2005

If a dielectric containing an electric field is compressed locally by a narrow acoustic pulse, the potential difference changes between the boundaries of the dielectric along the direction of travel of the pulse. This change in potential is dependent on the compressibility of the dielectric, on the pressure dependence of dielectric constant, and on the local macroscopic electric field in the region being compressed [A. Migliori and T. Hofler, Rev. Sci. Instrum. 53, 662 (1982)]. Because the pulse travels at the speed of sound, the potential difference is time dependent and can be used to map the internal electric field over the path of the pulse. We describe the theory of this measurement technique and present data taken with laser-generated acoustic pulses. The data demonstrate a sensitivity of 5 × 104 V/M and a resolution of 50 μM with an absolute accuracy of ± 5%. [Work supported by U. S. Department of Energy.]
Ultrasonic characterization of fatigue in advanced composite materials
Authors: Cantrell John H.
Published: October 2005

In contrast to fatigue of metals which tends to originate from crack initiation at identifiable defect sites, fatigue of fiber-reinforced composite materials has not been identified with a single dominant failure process. Rather, fatigue of such materials is manifested by several damage mechanisms including through-the-ply cracks, fiber disbonds, and delaminations. The presence of multiple damage mechanisms presents special problems both in understanding the fundamental nature of failure in fiber/matrix composites as well as in their nondestructive evaluation. Ultrasonic methods for characterizing fatigue damage in fiber/matrix composites will be examined with special emphasis on quantitative measurements of attenuation, velocity, and the values of the linear and quadratic attenuation coefficients measured as a function of frequency. The effect of ultrasonic phase cancellation errors due to material anisotropy and inhomogeneity as well as the influence of pulse shape artifacts on quantitative measurements are discussed.
Concert hall acoustics and number theory? Acoustic precision measurements with music??
Authors: Schroeder Manfred R.
Published: October 2005

Work at the Drittes Physikalisches Institut, University of Göttingen, on acoustic quality of concert halls is reviewed. Methods for better sound diffusion by reflection phase-gratings, based on three different principles of number theory, are described. The concept of the “modulation transfer function” (MTF) is exploited to use the music itself, as played during regular concerts in the presence of a full audience, to measure such important room acoustical parameters as reverberation time and early-to-late energy ratio.
ESPI—The ultimate holographic tool for vibration analysis?
Authors: Løkberg Ole J.
Published: October 2005

Electronic speckle pattern interferometry—ESPI—may be described as image holography, where the TV-target has replaced the the photographic film as recording medium while the optical reconstruction is simulated by videoprocessing and display. ESPI can do similar interferometric measurements as holography, but the technique is especially suitable for measurements on vibrating objects. Here the object's vibration mode is displayed as easily interpretable fringe patterns across the monitor image without time delay and at a high repetition rate. ESPI permits measurements on difficult, unstable objects in adverse environments. Using optical phase-modulation techniques in ESPI, we obtain an extended measuring range (lower-upper limits 0.01–10 000 NM), separate contours of constant amplitude and phase, dynamic display of the vibration cycle and direct comparison between vibrating objects. The ESPI technique has been applied in various industrial and biomedical projects, which will be described. The general properties outlined above together with some samples of vibrating objects will be illustrated by a short movie.
Pragmatic aspects of underwater transducer design
Authors: Mapes Theodore J.
Published: October 2005

The majority of failures experienced by underwater transducers are caused by deterioration of the materials which are employed to protect the active elements from the hostile effects of the seawater environment. In many cases such failures result from a poor choice of materials or from lack of consideration of the compatibility of the materials with themselves and with their environment. This paper reviews several case histories which highlight poor design practice in materials application. Guidelines for materials selection are promulgated in the hope that knowledge of past mistakes will provide insight towards avoiding repetition of these failures in future underwater transducer designs. Both organic and metallic materials are included in the study.
Text-independent speaker recognition with short utterances
Authors: Li K. P. , Wrench E. H.
Published: October 2005

This paper presents a new approach to text-independent speaker recognition. The technique, developed to perform with short unknown utterances, models the spectral traits of a speaker with multiple sub-models rather than using a single statistical distribution as done with previous approaches. The recognition is based on the statistical distribution of the distances between the unknown speaker and each of the speaker models. Only frames that are close to one of the speaker's sub-models are considered in the recognition decision, so that speech events not encountered in the training data do not bias the recognition. The technique has been tested on a conversational data base. Models were generated using 100 s of speech from each of 11 male talkers. Unknown speech was obtained one week after the model data. Recognition accuracies of 96%, 87%, and 79% were obtained for unknown speech durations of 10, 5, and 3 s, respectively. The use of multiple sub-models to characterize spectral traits results in improved discrimination between speakers, particularly when short speech segments are recognized. [Work supported by U. S. Air Force, Rome Air Development Center.]
Noise control of surface mine equipment—A retrofit approach
Authors: Marraccini Leonard C.
Published: October 2005

Noise problems exist in the mining industry as in other industries. Mobile surface equipment such as bulldozers, front end loaders, haulage trucks, and shovels generate noise, that for the most part, exceed current noise regulations. New equipment incorporate noise controls installed by the manufacturer. However, the large percentage of equipment are 5 to 10 years old or older and do not have noise controls installed. Over the last 5 years, a major effort has been put forth to reduce the noise exposure of the operators of these mobile equipment through the use of retrofit noise controls. Results of studies involving flammability of acoustic materials and various installation techniques were incorporated into the work. Results have been very successful with typical noise reductions of 8–12 dBA achieved. Material costs have run typically under $1000.
Peak flat sound pressure level of a sonic boom, with limited frequency response
Authors: Young Robert W.
Published: October 2005

Peak flat sound pressure (level) at a designated place is a frequently used measure of a sonic boom. Primarily to insure correct measurement of the initial peak of the shock (N) wave, a system fiat up to 10 kHz is often specified. Primarily to delineate the waveform in the middle of the N and thus to preserve the duration of the positive pressure phase, a system response flat down to 0.05 Hz is often specified. The shape of a measured waveform is changed drastically by relatively small changes in the high- and low-frequency limitations relative to the duration of the N wave. A measured positive transient can occur after the original N wave, which differs little from the measured initial positive transient. In a single graph, this paper provides an estimate how great an error is made in the measurement of peak sound pressure level of a theoretical N wave, when a system is used whose response is limited by a one-pole high-pass filter and a one-pole low-pass filter. As an example for a system with − 3 dB high-pass response at 8 Hz, and − 3 dB low-pass response at 1 kHz, if the duration of the N-wave is 400 ms, the expected error in measured peak sound pressure level is − 0.4 dB; if the − 3 dB response of the low-pass filter is raised from 1 to 4 kHz, the expected error is − 0.1 dB.
Acoustic backscatter from the ocean bottom
Authors: Goldsberry T. G. , Pitt S. P. , Lamb R. A.
Published: October 2005

In high-frequency sonar, the dominant interfering noise is virtually always reverberation, and the most important contributor to this reverberation is backscattered energy from the ocean floor. This has been long recognized and in 1964 McKinney and Anderson [J. Acoust. Soc. Am. 36, 158–163 (1964)] summarized the results of a comprehensive experimental investigation of bottom backscattering for a number of shallow water locations. Measurements have recently been made at a shallow water site near San Diego, CA that extend the range of bottom backscattering measurements to smaller grazing angles and narrower beam widths than previously reported. Preliminary results of analysis of these data are described and summarized. [This work was supported by Naval Ocean Research and Development Activity, Code 530.]
The Model 706 side-scan mapping system: A marine geophysical survey instrument
Authors: Darby Rolland L.
Published: October 2005

A radically new side-scan mapping system, featuring an evolutionary approach, has integrated multiprocessors for future growth and custom expansion, while maintaining compatibility with proven technology in transducers, towfish bodies, and electrographic chart recorders. The balance between hardware and software solutions has produced a relatively small, modular, easily maintained machine with features that extend beyond the total spectrum of previous side-scan systems. These features include the ability to generate true scale mosaics of the sea floor while simultaneously displaying bathymetric, subbottom, and altitude tracking data on a 19-in.-wide, dry paper, electrographic chart recorder. All processing is performed in real time with additional signal processing possible from magnetic tape during playback. Menu driven user programming simplifies operational use and includes self-test fault diagnosis. Fault tolerant software recovery insures minimum downtime, during surveys. The features and design philosophy are examined in detail followed by a discussion of operational performance data gathered during the last year. Custom enhancement capabilities for specific applications will be covered with details on typical configurations.
Effective sensor placement and intersensor processing parameter selection for covergence zone acoustic source localization
Authors: Peri Robert , Marshall Robert W.
Published: October 2005

The performance of an intersensor processing algorithm which seeks to localize a moving vessel radiating a narrow-band acoustic signal is dependent upon the placement of the sensors relative to the source, as well as on the cross-correlation algorithm and its processing parameters. Since the localization uncertainty is dependent upon the accuracy of the measurements of intersensor differential time of arrival, the processing bandwidth and coherent integration time of the correlator must be chosen in such a way as to maximize the output signal to noise ratio, while simultaneously avoiding decorrelation effects caused by source-sensor motion and nonidentical ocean transfer function (multipath) effects. In this paper we will demonstrate how a-priori estimates of the acoustic source spectrum, the source kinematics, and the propagation characteristics of the ocean medium were used to specify a reasonable deployment geometry for a set of distributed sensors and an effective set of correlation processing parameters for the over-the-horizon localization of a towed projector. [Work supported by NADC.]
Intelligibility of running speech using a tactile vocoder aided by lipreading
Authors: Brooks P. L. , Frost B. J. , Chung K. , Mason J. L.
Published: October 2005

In a previous paper [P. L. Scilley and B. J. Frost, J. Acoust. Soc. Am. Suppl. 1 69, S123 (1981)] we reported that an artificially deafened subject could identify 150 live spoken words using only the information obtained through a tactile vocoder. The vocoder consists of 16, 1/3-octave filters whose outputs, after detection and logarithmic amplification, are transmitted to a 16-channel linear solenoid array. The subject continued word learning at approximately the same rate until 250 words were identified. Presently, the subject's performance is being evaluated using (a) phrases derived from the 250-word vocabulary (b) novel words, and (c) novel phrases comprised of frequently occurring English words. This material is in an “open set” format with each stimulus presented only once so the subject has no idea of the stimulus possibilities. With no additional training after the word learning experiments the subject could understand and correctly repeat 81% of the (a) phrases, 75% of the (b) words, and 75% of the (c) phrases using the tactile vocoder plus lipreading. In the lipreading alone condition 59% of (a) phrases, 40% of (b) words, and 48% of the (c) phrases were repeated correctly. [Work supported by National Health and Welfare Canada.]
A computer-controlled high pressure hydrophone calibrator
Authors: Crooks Robert E. , Powers James M.
Published: October 2005

A computer-controlled calibration method was developed which measures the quasistatic receiving sensitivity of piezoelectric hydrophones over a 0 to 7 MPa pressure range. In this method, a pressure step is applied to the hydrophone and the resulting change in charge is measured. This procedure is repeated over the desired pressure range and a plot hydrophone sensitivity versus pressure is generated. Hydrophones up to 10×10×30 cm in size can be calibrated. A microcomputer was used to handle the large number of repetitive measurements and to perform arithmetic operations, graphic display, and data storage. [Work supported by NAVSEA code 63R.]
The 3-3 parameters for piezoelectric ceramics: New parameter-measurement relations and transducer design implications
Authors: Martin Gordon E. , Johson Jeffrey L.
Published: October 2005

Many underwater acoustic transducers are designed to utilize the 3-3 mode of piezoelectric ceramic materials. The dominant elastic transducer parameter for such segments and stacks is s33D [G. E. Martin, J. Acoust. Soc. Am. 35, 510–520 (1963); 36, 1496–1506 (1964)]. Usually each segment is an annular ring and the direct measurement of s33D is not considered valid. This paper describes parameter evaluation techniques for such 3-3 parameters based upon finite element analyses of a short, thick annulus with relatively large cross section. The measured thickness resonance and antiresonance frequencies are related to the parameters using the equations for a long 3-3 bar with correction factors. The correction for s33D is small and for k33 it is nearly 10%. Experimental results for the ring for 20°–120°C showed that s33D is relatively constant whereas dielectric constant and coupling coefficient k33 are strongly dependent upon ambient temperature. Transducer design and reliability implications due to these 3-3 parameter result are discussed. Prior parameter-measurement relations are reviewed and compared to analyses here based upon finite-element models. [Work supported by NAVSEA 63X.]
Modal coupling in vibrating plates
Authors: Caldersmith Graham , Rossing Thomas D.
Published: October 2005

In square isotropic plates, some of the degenerate mode pairs are split in frequency due to coupling between longitudinal and transverse strain (which might be called Poisson coupling), and the same splitting of degenerate modes may occur in rectangular orthotropic plates having a certain length/width ratio. We have studied this coupling in free plates of aluminum and spruce (quarter-cut and skew-cut) and determined Poisson's ratios from the frequency ratio of the (2,0 ± 0,2) modes (called the X and ring modes by Luthiers). The critical length/width ratio was found to be considerably greater (3.2) in the skew-cut spruce than in the quarter-cut spruce (2.1), due to the smaller cross-grain elastic modulus and Poisson ratio.
Interaction of ultrasonic waves by periodically rough liquid-solid interfaces
Authors: Adler L. , Jungman A. , Claeys J. M. , Leroy O.
Published: October 2005

When a broadband ultrasonic wave interacts with periodically rough liquid-solid interfaces at normal incidence the reflected spectrum contains several minima which are characteristics of the various parameters of the interface as reported earlier [J. Acoust. Soc. Am. Suppl. I 68, S81 (1980)]. An analytical approach to this problem will be discussed which uses general boundary conditions suggested by Poiree [Rev. Cethedec 39, 21–24 (1974); 48, 7–34 (1976)]. These boundary conditions are expressed in terms of continuity of functions involving velocity field v, and stress tensor Tij in liquid and solid, respectively, as: V1 ⋅ ∇φ = V2 ⋅ ∇φ and Σj = 13 Tij1(∇φ)j = Σj = 13 Tij2(∇φ)j, where φ(x,z) = f(x) − z defines the profile. The frequency dependence of the reflection coefficient is calculated for various surface parameters. Correlation between height of the irregularities and intensities of diffracted orders is shown to depend mainly on the characteristics of the solid. Theoretical results for the reflected spectra are in very good agreement with experiments. [Work partially supported by the National Foundation of Belgium.]
Thermoviscous effects on acoustic scattering by elastic solid cylinders and spheres
Authors: Lin Wen H. , Raptis A. C.
Published: October 2005

This paper presents analytic solutions and numerical results of the scattering of plane sound waves from a thermoelastic circular cylinder and from a thermoelastic sphere in an infinite, thermoviscous fluid medium. The thermoelastic properties of the cylinder and the sphere and the viscosity and thermal conductivity of the surrounding fluid are taken into consideration in the solutions of the acoustic-scattering problems. The associated acoustic quantities, such as the acoustic-radiation force, the acoustic attenuation, and the acoustic-scattering pattern, are first derived in closed forms and then evaluated numerically for a given set of material properties. Numerical results show that increasing fluid viscosity tends to increase the magnitudes of the acoustic-radiation force, the acoustic attenuation, and the angular distribution of the scattering pattern. However, the opposite trends are observed when the fluid temperature increases. The plots of the acoustic attenuation coefficients versus the dimensionless wavenumber of the incident sound wave reveal oscillatory phenomena, which are caused by the resonant vibrations of the cylinder or the sphere.
Image formation by multiple shading
Authors: Jones C. H. , Thompson J. H. , Kesner J. W.
Published: October 2005

A novel method for obtaining an improved image from an array of hydrophones is described. The technique involves generating a set of different images. These images are then combined using an appropriate algorithm. The composite image is superior to any one of the original images. The technique achieves good angular resolution with low spurious side lobes. Three examples are given for a 16-element array using computer simulation. The procedure is applicable to line arrays, planar arrays, and conformal arrays.
Acoustic loading in planar networks
Authors: El-Raheb M. , Wagner P.
Published: October 2005

The acoustic pressure in complex planar networks is determined by a method which adopts Green's function surface elements. The boundary of each duct is discretized into small straight and circular elements each carrying a source density of constant strength. This process enables us to convert the Fredholm integral equation in the source density into a set of linear algebraic equations. Increase in computational efficiency is attained using the transfer matrix technique. Basically, the influence coefficients including elements on the interface of conjoined ducts are determined separately for each duct in the network. The unknown source density vector on the walls is expressed in terms of the source density vector at the junction lines. Enforcing compatibility of acoustic pressure and velocity at the interface of consecutive ducts determines a system of linear algebraic equations in the form of tridiagonal blocks. The transfer matrix approach is best suited for long configurations formed by repeated patterns of straight, circular, and branched ducts. The computation of transfer matrices is then limited to a few basic building segments of the network.
Auditory signal processing in hearing-impaired persons with residual high-frequency hearing
Authors: Long Glenis R. , Cullen John K.
Published: October 2005

A number of persons with severe sensorineural hearing losses in the frequency range below 6000 Hz have been shown to have near-normal thresholds for frequencies above 6000 Hz. This paper reports on measures of high-frequency signal processing in seven persons with this type of heating impairment. Measures taken include estimates of difference limens for intensity and frequency, gap detection, rate discrimination, and narrow-band masking functions. Although little normative data exist for comparative purposes, measures of frequency, intensity, and time resolution are within the range of what one would anticipate by extrapolation. Intensity and frequency differences limens, and wideband and narrow-band masking functions also were obtained in the region of impaired hearing {i.e., 3–6 kHz}; narrow-band masking measures and difference limens indicated impaired frequency processing and varied between subjects. Intensity discrimination fell within previously published ranges. [Work supported by the National Institutes of Health.]
Portable programmable calculator control of acoustic analyzer
Authors: Brack Michael
Published: October 2005

The recent introduction of the Hewlett-Packard Interface Loop (HPIL) has provided the means for interfacing the Ivie IE-30A 1/3-octave, real-time analyzer to the HP-41C programmable calculator resulting in a small portable system for detailed spectrum analysis in the field. A battery-powered interface is described which, in conjunction with the HP-IL converter, allows the HP-41C to read in the 1/3-octave or octave band spectrum to its memory with 0.2-dB resolution over a 50-dB dynamic range. The weighted level from the SLM portion can also be read into memory with about 0.5-dB resolution. Some of the programs developed for this system are described. These include a program to average spectra for use in determining the space-average SPL in a room from a moving microphone, which can then be printed out, stored to memory, magnetic card, or cassette for use in noise reduction, equalization or other calculations. Machine language programming of the HP-41C will also be discussed for use in speeding up data manipulations by a factor of 10 to 50 times over that of normal user code.
A case history of noise control for a laboratory with fume hoods
Authors: McKay Ronald L.
Published: October 2005

Centrifugal fans of fiberglass construction and with radial blades were employed to exhaust fume hoods in a medical research facility. The result was high sound levels with annoying blade-passage tonal peaks both indoors and outdoors. Initial sound levels will be presented, as well as reduced levels after the installation of duct silencers. Level distributions within rooms will be shown. Comparisons will be made between actual measured insertion loss of silencers and published insertion loss. Silencer acoustical performance with respect to location in the fan-duct system will be discussed. [Work supported by Daniel, Mann, Johnson, and Mendenhall.]
Ocean bottom seismic instrumentation
Authors: Duennebier Frederick K.
Published: October 2005

During the past several years the quality of seismic data obtained in the deep oceans has improved markedly due to the development of better instrument packages and recording systems. These improvements take advantage of improved understanding of the seismic coupling problem, the effects of ocean currents, and Stoneley waves. The coupling problem arises from the inability of an ocean bottom seismometer (OBS) to move with the ocean bottom in response to seismic waves when the bottom is soft. The transfer function between the motion of the bottom and the OBS is good at very low frequencies and poor at high frequencies, the corner depending on the softness of the bottom and the mechanical characteristics of the OBS. The buoyancy of the OBS also has a pronounced effect on the response. These coupling effects are not observed on hydrophones. Several solutions to the above problems are being proposed and tested. First, since many of the problems with collecting high quality seismic data on the ocean floor are related to the ocean bottom interface, one solution is to remove the sensors from the interface and place them in drill holes under the ocean floor. This operation is considerably more expensive than emplacing OBS's but preliminary results suggest that the increase in data quality is significant. Solutions to the coupling problem include sensor burial, increasing the surface area in contact with the ocean bottom, and making sensor packages neutrally buoyant in the sediments. Current noise problems are greatly improved by decreasing the OBS cross section to the water. Stoneley wave generated noise is truly seismic and can be discriminated against by using multiple sensors or hydrophones that are much less sensitive to these signals.
Propagation of acoustic surface-wave pulses
Authors: Gaunaurd G. C. , Überall H. , Subrahmanyam J. V.
Published: October 2005

Surface waves on impenetrable or on elastic objects, produced by acoustic scattering or by other mechanisms, show pronounced dispersion effects. Their dispersion curves may be obtained from the resonances exhibited by their amplitude function either in the complex frequency plane (“SEM” or singularity expansion method poles) or in the complex mode number plane (“Watson poles” or “Regge poles”) [such acoustic resonances have recently been observed and analyzed by Maze, Taconet, and Ripoche, Phys. Lett. A 84, 309 (1981)]. Accordingly, the propagation of surface-wave pulses, and their arrival times, are determined by their group velocity. This is demonstrated by summing the normal-mode series of the surface wave portion of scattering amplitudes on spherical and cylindrical surfaces, using a stationary-phase approach. At the stationary points, which determine the pulse arrival times, there occurs a coherent summation (constructive interference) of the normal modes, and the stationary condition is recognized to lead to the correct propagation of the pulses with group velocity. [H. Überall is also at Catholic University, Washington, DC and is additionally supported by ONR.]
Approximate closed form solution to the generalized interface wave speed equation
Authors: Wilbur JoEllen , Claus Richard O. , Gray John W.
Published: October 2005

An approximate closed form solution for the speed of generalized surface acoustic waves which are bound to a thin layer separating two infinite half-spaces is presented. The exact form of the characteristic equation is first derived by considering the usual requirements of particle displacement and stress continuity at both layer-substrate boundaries [J. P. Jones and J. S. Whittier, J. Appl. Mech. 905 (Dec. 1967)]. It is then noted that in many cases the interface wave speed is less than half the lower longitudinal wave speed and as much as 5% less than the lower shear wave speed. After expressing terms involving ratios of these speeds in the exact equation as series expansions, this has been used to neglect appropriate small terms and to simplify the resulting equation. Additional simplification yields approximate closed form expressions for all 12 complex roots. Variations in these solutions as a function of the viscoelastic properties of the boundary layer are compared with theoretical [V. Kumar and G. S. Murty, IEEE Trans. Sonics Ultrason. SU-29, 138 (1982)] and experimental results [R. O. Claus, J. Phys. (Paris) 42, CS-1159 (1981)]. [Work supported in part by NSF and NASA.]
Water permeation through elastomer laminates
Authors: Cassidy Patrick E.
Published: October 2005

Neoprene and EPDM elastomers were used to measure the permeation rates of distilled water and salt water at 23°, 40° and 60 °C. For laminates, the rates were measured in both directions. The laminates showed a directional dependence of permeation rate and rates lower than the arithmetic mean of the two single layers. Effect of temperature on permeation rate had an Arrhenius type behavior and the activation energies fall within the range for those membranes that follow activated transport mechanism. Tentative mechanisms were proposed for the directional flow behavior in regard to concentration-dependent permeation.
Vibrational modes of a handbell
Authors: Perrin Robert , Peterson Richard W. , Rossing Thomas D. , Sathoff H. John
Published: October 2005

The vibrational modes of a small handbell tuned to C5 (523 Hz) have been calculated by means of a finite element method, and also measured by means of holographic interferometry as well as by scanning the sound field close to the bell. The frequency ratios calculated for the various modes as well as the locations of the nodes are found to be in good agreement and also consistent with those previously reported [T. D. Rossing and H. J. Sathoff, J. Acoust. Soc. Am. 68, 1600 (1980)]. Only two flexural modes without nodal circles are observed; these have two and three complete nodal meridians, respectively (m = 2 and 3). For m > 3, the modes without nodal circles are replaced by a family of modes having a nodal circle near the mouth of the bell, similar to those observed for m > 4 in a large handbell [T. D. Rossing, Overtones 29 (1), 15 (1983)]. The finite element analysis also predicts several extensional modes and other modes that have not yet been observed experimentally.
A new model of an auditory nerve fiber
Authors: Donhouédé Blaise , Dolmazon J. Marc
Published: October 2005

The main temporal characteristics of discharges observed in the primary auditory neuron are the phenomena of adaptation and synchronization of the responses on the phase of the stimulus. These phenomena play a major role in the mechanisms of speech coding [Delgutte, J. Acoust. Soc. Am. 68, 843 (1980)]. We propose a stochastic threshold model which mainly asumes that the process of adaptation is additive. This model reproduces appropriately adaptation and its per-stimulatory effects. It simulates in the same way the locking of nerve discharge to the stimulus cycle up to about 5000 cycles/s, in accordance with experimental results (Anderson et al., J. Acoust. Soc. Am. 54(2) (1971)]. In comparison with other threshold models, the originality of ours lies in the fact that it includes the temporal evolution of graded potentials described by Furukawa et al. [J. Physiol. 276 (1978)].
Point process model of LSO unit discharges
Authors: Johnson Don H. , Linebarger Darel , Tsuchitani Chiyeko
Published: October 2005

A point process model for the responses of single auditory-nerve fibers to time-varying stimuli was extended to describe lateral superior olive (LSO) unit responses to monaural cf tones. In contrast to auditory-nerve fiber discharges, successive interspike-intervals of LSO unit discharges exhibit serial dependence. This dependence was found to be well described by a first-order Markov model of the underlying point process. The characteristics of this model were measured from the conditional interval histogram: the usual interspike interval histogram restricted to those intervals preceded by an interval of a specified duration. From this quantity, the conditional hazard function was derived. This computation revealed that the influence of the pentultimate interval was to shift the hazard function. This detailed description of the serial dependence cannot be derived from measurements of serial correlation coefficients. The cf tone burst responses of LSO units are characterized as “chopper”-type. Within the context of the point process model outlined above, the parameters of the model were measured from the sustained portion of the tone burst response. Using the model thus derived, the initial chopping portion of the response was predicted. [Work supported by NINCDS and NSF.]
Materials used by industry for the production of piezoelectric transducers. The state of the art of research work performed in the field of PZT ceramics and ferroelectric polymers
Authors: Eyraud Lucien , Eyraud Paul , Bauer François
Published: October 2005

For inorganic materials such as piezoelectric PZT ceramics, the phenomena of conduction and aging set severe limits to the development of some industrial applications. Various models, in particular that of a suggested structure model, allow one to get insight into these phenomena and to limit these effects by acting either on the manufacturing process or on the composition itself. For organic materials, in contrast, the phenomena are quite different and, from the outset, the problems are much less severe. A brief review will be given of the properties of the PVF2 homopolymer as well as of a few copolarized in a suitable manner. These organic and inorganic materials must be taken into account as strong candidates for the production of new transducers.
Simulation of flow through a parametrized “reed-aperture”
Authors: Strong William J.
Published: October 2005

In systems used to simulate wind instrument behavior the blowing pressure is often set to some constant value. This is equivalent to assuming that the blowing pressure source (lungs-bronchi-trachea-vocal tract) has an internal impedance that is small in comparison with reed-aperture plus tube impedance. A stylized pressure source plus reed-aperture plus tube is simulated to investigate the effects of source characteristics and tube characteristics. The pressure source is represented by one of four configurations: large cross-sectional area vocal tract, small cross-sectional area vocal tract, an /a/-shaped tract, and an /i/-shaped tract. The rectangular “reed-aperture” is parametrized so that its time variation is independent of any source or tube loading. Four “tube” loadings are simulated: a zero impedance, a resistance, an inertance, and a section of uniform tubing. Waveforms and spectra are calculated for air flow through the reed-aperture, blowing pressure, and tube pressure for the 4 × 4 = 16 possible combinations to demonstrate the effects of source and tube characteristics.
Semi-empirical formula for the clarinet spectrum
Authors: Benade A. H. , Kouzoupis S.
Published: October 2005

A single formula is presented giving the normalized strengths (pn/p1 of the harmonics belonging to any note of a clarinet's scale. The formula is based on Worman's internal spectrum systematics, a transformation function connecting this with the external (room average) spectrum, plus the pipe-scaling relations for air column damping. Any note is characterized by the ratio F of its fundamental frequency f1 to the instrument's essentially constant tone hole lattice cutoff frequency fc. The playing level is specified by L = (p1/p0) where p0 is the value of p1 when the reed just beats (L < 1). (pn/p1) = Ln [1 + α(nF)6]−1/2(1 + βF1/2e−γF n)e DN. For n odd, e = ± 1 and D = 1. For n even, e = − 1 and D = nF/(1 + nF). Here N normalizes to unity at n = 1, α = 0.85, β = 8.5, γ = 3, as fitted to the clarinet C4 (where F≃1/6.5) at L = 1. A fixed-parameter filter set can be built, which when driven by a constant-width pulse train having a repetition rate corresponding to any desired note, can well approximate the clarinet's spectrum for L = 1. A-B listening tests against a real clarinet show good matching over the entire scale. Analogous spectral formulas and filter sets for other wind instruments appear possible.
The legal aspects and economic feasibility of engineering noise controls; origin and developments of cost/benefit
Authors: Barnako Frank R.
Published: October 2005

In Continental Can Company the respondent defended a citation for violation of the noise standard 29 C.F.R. 1910.95 raising the question of economic feasibility of technological controls as compared with an effective hearing conservation program. The Occupational Safety and Health Review Commission (OSHRC) in a two to one decision held that feasibility as used in the standard contemplates economic as well as technological feasibility; that the cost of engineering controls, loss of production or efficiency, if any, together with annual maintenance costs thereof and the reasonably expected noise reduction must be weighed against the cost of an effective hearing conservation program. The Commission held that under that test the cost of controls was excessive and vacated the citation. Subsequent Review Commission decisions in Turner Company, Samson Paper Bag Co., Inc., Carnation Co., Louisiana-Pacific, RMI, International Harvester, and Castle and Cook developed the application of that decision in various factual situations and following decisions of the United States Circuit Court of Appeal. The definitive case of Castle and Cook in the Ninth Circuit sustained the Commission in its position. The Court deferred to the Commission's expertise as a “independent adjudicator” and agreed that the Act and Standard required only those controls economically justified after analyzing costs of controls versus benefits obtained by effected employees from an effective hearing conservation program. The citation was dismissed.