bluuebunny/crossref_metadata_2025 huggingface dataset:
Listener preferences and spectral similarities of eigenparameter quantization schemes for speech
Authors: Strong William J. , Robinson Kem E.
Published: October 2005

Several quantization schemes for eigenparameters of speech have been studied as part of an effort to determine a set of spectral patterns that will be adequate to synthesize speech having the characteristics of, a particular talker. This paper describes an experiment in which sentence material from each of two male and two female talkers was analyzed using an autocorrelation method to obtain 12 log area ratios at 10 millisecond intervals. An eigenparameter analysis was then performed on the log area ratios. The eigenparameters were quantized in each of six ways based on their variance and standard deviation. Ten versions of speech were created for each talker: one was natural, three were synthesized from nonquantized parameters, and six were synthesized from quantized parameters. Each version of speech was paired with all other versions and listeners were asked which of the two versions in a pair they preferred. The same quantization schemes did not produce the same listener preferences for all talkers. Average spectral similarities of each quantized version (relative to a 12 parameter version) were also calculated using the minimum prediction residual and an ad hoc measure that maintains distance symmetry between “sample” and “template.” The results will be considered in terms of how well measures of spectral similarity correlate with listener preferences.
Decomposing speech into formants: A new look at an old problem
Authors: Atal Bishnu S. , Shadle Christine H.
Published: October 2005

We describe in this paper a method of decomposing a speech wave into a number of elementary signals representing the contribution of the individual vocal-tract resonances. The decomposition is achieved by filtering out all but the desired resonance component from the speech wave on the basis of a suitably defined criterion of smoothness. The method assumes that the waveforms of the individual resonances can be distinguished according to the smoothness criterion. The parameters of the filter vary with time according to the changing character of the vocal tract resonances. Typically, the filter coefficients are adjusted once every pitch period. The number of filter coefficients equals the number of complex resonances of the vocal tract. In addition to excitation parameters, each elementary signal is described by four parameters representing the frequency, amplitude, bandwidth, and phase of a particular formant. The method provides an automatic method of extracting formant parameters for speech recognition and synthesis.
Articulatory movements by time optimal control
Authors: Shigenaga M. , Ariizumi H.
Published: October 2005

Whenever a muscle contracts, a counter force is produced by the antagonistic muscles through tactual and auditory feedback. This paper describes a model for the articulatory movements controlled by a switching force (time optimal control). The vocal tract in transition from one phoneme to another is shaped as follows: The lateral shape of the vocal tract for each phoneme is decomposed into two component shapes for the tongue and the jaw. Then each point on each articulator is moved toward the corresponding point on the target shape under the assumption of a modified time optimal control. The control force is adjusted considering the features of each phoneme, the distance between the initial and the target shapes, and the speed of utterance. For example, the transition between vowels is controlled by a simple switching force, while a large additional force is temporarily applied to the tongue for the transition between a consonant and a vowel. ,The vocal tract is shaped by combining the two component shapes. Thus, the model can simulate the processes of coarticulation at an arbitrary speech rate and can be used for synthesis by rule of connected speech. [Work supported by Ministry of Education Grant-in-Aid for Scientific Research No. 239005.]
Automatic voice answerback using text to speech conversion by rule
Authors: Denes P. B.
Published: October 2005

A system for the rule synthesis of voice answerback sentences for telephone directory-assistance purposes is described. The sentences have the form “The number for (Mr. John Doe) of (213 Brooklands Road) is (987–6543).” Research on such a system offers the attractions of a genuine practical application for rule synthesis. It combines a nontrivial text-to-speech conversion task for the large numbers of names and addresses involved, yet avoids many of the unknowns associated with the synthesis of general English text because only a single carrier sentences is used. The task is performed in two steps. First the text is converted by rule into phonetic transcription, including stress and segment durations. This serves as input to the second part in which an intonation pattern is selected and dyadic concatenation of area function segments is used to calculate the acoustic wave. Recorded examples of the resulting speech will be played. The two stages of the synthesis process will be described in the two papers that follow.
Speech synthesis from phonemic transcription
Authors: Olive Joseph P.
Published: October 2005

In this paper we will describe the portion of the text-to-speech conversion system which accepts a phonetic transcription, stress, and timing information as its input, and outputs the corresponding speech wave. The synthesis program is a form of dyadic concatenation of LPC area segments obtained from natural speech; in addition, the program also calculates the amplitude and intonation. The dyadic concatenation is performed using a matrix of phoneme transitions to obtain the LPC area parameters; the amplitude is obtained by rules which depend on the class of the phonemes involved in the amplitude computation. The fundamental frequency contour is obtained by an adjustment of a stored fundamental frequency contour to fit the utterance to be synthesized. This adjustment is performed by selecting the portion of the stored fundamental frequency contour which fits the number of words and their function in the utterance. The location of the peak of the contour for each word in the utterance is then adjusted to fall at the location of the primary stress.
Near grazing scattering by slightly rough surfaces
Authors: Bailie J. , Medwin H.
Published: October 2005

Point source radiation which is at near-grazing incidence to a slightly rough surface generates a boundary wave in the fluid as well as the better known volume wave [I. Tolstoy, J. Acoust. Soc. Am. 63, S60(A) (1978)]. The boundary wave is weaker at larger distances of source and receiver from the boundary. However, it can dominate the volume wave at sufficient ranges when source and receiver are near the surface. In backscatter, where only the boundary wave exists, the signal strength increases with increasing frequency until one reaches a critical frequency which is a function of source and receiver heights and a scattering parameter which describes the rough surface; beyond this frequency this behavior is reversed. Anechoic chamber experiments, using a surface constructed of rigid hemispheres on a rigid plate, are compared with theory. [Work supported by the Office of Naval Research.]
Monostatic surface backscatter strength observed at the Azores Fixed Acoustic Range
Authors: Freese Herbert A. , Buehler Barry G.
Published: October 2005

Monostatic surface backscatter strengths were measured at the Azores Fixed Acoustic Range (AFAR) using a directive antenna which was steerable in both azimuth and elevation. Observations of scattering strength were made under the following conditions: grazing angles of 20°–90°; wind speeds of 5–25 knots; transmission frequencies in the range 500–5000 Hz; and various directions with respect to the surface swell. These results are compared with the results of Chapman and the theories of Barrick.
Microbubble distribution measurement using acoustic backscatter
Authors: Malme C. I.
Published: October 2005

Surface reverberation at low grazing angles and sound propagation in the mixed layer are influenced by microbubble layers near the surface. Acoustic extinction measurement over short propagation paths [Medwin, J. Geophys. Res. 82(6), 971–976 (1977)] has been used to obtain in situ data on bubble density and size as a function of depth. We have investigated another microbubble measurement technique which uses backscattered acoustic energy. Short, broadband acoustic pulses are projected at normal incidence to the surface from a directional transducer system mounted on a tow-body. The backscattered signal is received and analyzed to determine the volume scattering strength vs frequency and depth. The resulting data permit calculation of the bubble size and density distribution. Measurements conducted in Dabob Bay are described during which a bubble layer depth of about 30 ft was observed following a period of 30-kt winds. Microbubble distribution measurements were made over a three-day period during the decay of this layer. The projected signal was a 1.5 ms pulse of white noise, bandlimited to 32– 62 kHz. Results obtained using this technique are compared with reported microbubble distribution data from acoustic extinction measurements.
Correlation between small-scale temperature gradients and acoustic scatterers
Authors: Kaye G. T.
Published: October 2005

Reverberation data taken from R/P FLIP off southern California with a narrow-beam 87.5-kHz echosounder have been compared with temperature profiles obtained every two minutes over a nine-hour period. Prior to the rise of the Deep Scattering Layer and for approximately an hour after migration, there was a positive correlation between the temperature gradient fine structure and the scattering intensity profile. After this time a diffuse downward migration was observed until there was a negative correlation between the profiles. High frequency internal waves were shown to be accurately depicted in the acoustic information. It is suggested that biological sampling techniques to demonstrate faunal patchiness would be greatly aided by acoustic monitoring during the observations.
A source level model for propeller blade rate radiation for the world's merchant fleet
Authors: Gray Leslie M. , Greeley David S.
Published: October 2005

The total unsteady cavitation volume on a given propeller, which generates radiated noise at propeller blade rate and harmonics, can be bounded from basic design considerations. At a vessel's design speed, an upper limit to this unsteady cavitation exists from considerations of excessive ship vibrations, and a lower limit exists from considerations of propeller efficiency. This paper presents a model for blade rate radiated noise from merchant ships which is based on these design limitations for cavity volume, and an elementary radiation model. A sample survey was made of the propeller characteristics of the world fleet, which allows the further derivation of a source model based on physical characteristics of a given ship, including a definition of the uncertainty of the estimate. This model is exercised for the estimated merchant ship population at sea and a stochastic representation is derived for the source levels and frequencies to be expected for this merchant fleet operating at its design speed.
Depth dependence of the vertical directionality of low-frequency ambient noise in the ocean
Authors: Morris G. B. , Tyce R. C.
Published: October 2005

A long vertical array of hydrophones was used to measure the vertical directionality of ambient noise in the ocean in the 10–50-Hz frequency band. These measurements were made in deep water, 4300 m, at a site approximately 350 miles west of San Diego. The array was positioned at five different depths within the water column, ranging from near the surface to near the bottom. At all depths, most of the low frequency noise is concentrated in a near horizontal direction. At positions in the upper part of the water column, the −3 dB points on the measured beam noise level occur at about ±13° away from the horizontal (the horizontal direction being 0°). This angular sector decreases with increasing depth so that when the array is near the bottom, the measured beam noise is concentrated in an angular sector of ±4° as measured from the horizontal. [Work supported by NORDA Ocean Program Office.]
Horizontal directivity of ambient noise associated with a shipping lane
Authors: Bannister R. W. , Wagstaff R. A. , Aitkenhead J. W.
Published: October 2005

A simple analytical model of the horizontal noise field associated with a shipping lane has been developed which is based on a set of acoustic line radiators having uniform linear source density. This simple model has been computer coded and compared with a more complex model containing dynamic positioning of up to 1500 discrete ships. It was found that the simple model gives a comparable estimate of the smoothed horizontal noise field and also provides physical insights into the factors determining horizontal directionality of ambient noise in the ocean. In this presentation, the line radiator model is used to investigate the sensitivity of the shape and magnitude of the horizontal noise field related to a single arbitrary shipping lane. Parameters studies are lane widths and cross-sectional shape, distance from receiver point as well as the effects of different propagation conditions [work supported by Office of Naval Research (Long Range Acoustic Propagation Program) and Defence Scientific Research Establishment, NZ.]
Historical temporal shipping
Authors: Solomon L. P. , Barnes A. E. , Draper P. J. , Alessi T.
Published: October 2005

Shipping distributions serve as primary inputs to ambient noise models. Past work [Solomon et at., J. Acoust. Soc. Am. 62, S39(A) (1977)] discussed the generation of the tools necessary to calculate the present distributions. Shipping distributions by month, quarter, and annual average have been developed for numerous ship classes. These are world wide and presented in the form of 1° square distributions. The ships are partitioned into the following categories: tankers, VLCCs, ULCCs, general cargo, fishing and others. Numerical distributions produced by the computer codes have been validated by comparison with actual measurements in selected ocean areas. [Work supported by ONR.]
Blade rate radiation from merchant vessels
Authors: Greeley David S.
Published: October 2005

Acoustic radiation from merchant vessels at blade rate frequency and harmonics is caused by direct radiation from cavitation volume fluctuations and from forced vibration of the ship hull caused by unsteady propeller forces. Reciprocal measurements were made on a structural scale model of a 600-ft tanker (1: 100 scale) to determine the relationship between forced ship hull vibration and radiated power. Unsteady propeller forces have been predicted theoretically in order to estimate the acoustic power radiated by ship hull vibrations. Analytical methods have been used to predict cavitation volume fluctuations and the acoustic power radiated by these fluctuations. For a typical single screw merchant vessel, it is shown that the acoustic power at blade rate and harmonics radiated directly from cavitation volume fluctuations will dominate over the radiation from the hull response to unsteady propeller forces.
Wide frequency response of Type J-9 underwater sound projector in a reverberant tank
Authors: Curtis George D.
Published: October 2005

The characteristics and use of the Type J-9 transducer at frequencies up to ten times its calibrated range are discussed, and described quantitatively. Problems and precautions in using this and other projectors in reverberant experimental test tanks are covered. Examples of temporal, spatial, reverberation and directive effects are presented. Recommendations for effective use of high frequency sound projectors such as this, proper experiment design, and valid interpretation of results are made. [Work supported in part by NSF Grant BNS 76-81926.]
An onionskin composite as a transducer backing material
Authors: Behrens John A. , Blankenship G. W. , Stokes Robert H.
Published: October 2005

This paper describes the use of an onionskin composite for the backing material of piezoceramic elements in a high frequency array. It is the purpose of this paper to compare certain advantages of using this particular composite over a more rigid type material. Measurements on experimental test arrays consisted of single stave patterns and receiving responses versus hydrostatic pressure. In order to show that a sonar array performance can be affected by the piezoceramic backing material, calculated array pattern data, based upon measured and calculated single stave patterns, are presented in tabular form. The fabrication technique of putting the onionskin on a curved face housing is presented. In the process, the composite is precompressed such that, after potting the array in polyurethane, it will withstand high hydrostatic pressures without an extreme degradation in the sound isolating, tuning, and reflecting properties of the array.
Effect of transducer thickness and transducer backing material on the convergence of an incident ultrasonic pulse
Authors: Altman H.
Published: October 2005

Analysis of calculated pulse shapes for ultrasonic waves reflected from a plane transducer is made with respect to the effect of transducer thickness and transducer backing material. Conditions affecting convergence of the amplitude value of the infinite series of pulses internally reflected in the transducer are discussed in detail. The significance of the acoustic impedance of the sample under study as well as that of the transducer is shown to be an essential criteria in selection of transducer backing material.
Pressure radiation from the exploding wire
Authors: Matsuda M.
Published: October 2005

The exploding wire impulse source is a progressive one as compared with other high intensive impulse sources. Especially, it can achieve 10%–20% in efficiency, about 0.99 correlative degree in reproducibility and arbitrary directional characteristics with using the bent wire. The practical estimation of the acoustic sound radiation can be obtained by assuming that the initial state of wire has been ionized uniformly, as the difficulties are laid down in the exact estimation of the initial wire state. In the optimum condition of wire available for the circuit conditions, the image of the wire source (P) may be converted into an idealized line source (P1). Therefore, the radiational characteristics can be calculated by simple form, and this agrees well with the experimental results: ∀P1∃Pp (idealize; P1 → Pp), so, P = ∪P1 ⇒ P1 = ∪Pp: Pp; point source. Supplying wire, one of the practical problems, may be conquered by using the thin metal film explosion and it can be expressed in a similar form to the wire explosion.
High-frequency vibrations of rectangular crystal plates coated with multiple strip electrodes
Authors: Zee Charles , Lee P. C. Y.
Published: October 2005

The two-dimensional equations of motion for the vibrations of crystal plates developed by Lee and Nikodem are extended to incorporate the mass effect of electrode platings on a crystal plate. These, together with the unplated equations of motion, are combined to govern the motion of an elastically coupled piezoelectric resonator system with multiple strip electrodes. A rectangular AT-cut quarts plate with the strip electrodes which are parallel to the X1 axis and cover the full length of the plate in X1 direction are considered, X1 being the digonal axis of the crystal. Closed form solution is obtained for the coupled thickness-twist and face-shear vibrations, which satisfies the traction-free conditions at edges of the plate and the continuity conditions for traction and displacement at the junctures of the plated and unplated regions of the plate. The calculated results are compared with experimental values with close agreement. Then the dependence of the inter-resonator coupling, resonance frequencies, and vibrational modes on the electrode mass, on the dimensions of the electrodes' configuration, and on the plate geometry are studied and analyzed.
Development of lightweight compliant tubes for hydroacoustic baffles
Authors: Maple R. D. , Gay R. B.
Published: October 2005

Compliant tube baffles have proven very effective for self-noise reduction in the development of two-dimensional sonar receiving arrays. The in-water weight of such baffles, when composed of alloy steel tubes, has been the principal limiting factor in their use on large area arrays. A review of high strength to weight materials has led to the evaluation of graphite composites as a potential replacement for steel which will provide near neutrally buoyant baffles. Modal analysis of individual tubes in air, acoustic testing of single layer gratings in water, as well as hydrostatic pressure and strength of materials tests have supported this selection. In addition, the feasibility of using flat plate tubes fabricated from either aluminum or fiberglass has been demonstrated. This fabrication technique allows not only lighter, but less difficult to fabricate, lower cost compliant tubes. [Work supported by Naval Sea Systems Command.]
New developments and alternatives in compliant tube technology
Authors: Libuha J. J. , Brigham G. A.
Published: October 2005

The need for high compliance devices coupled with great strength and lightweight construction has generated interest in making compliant tubes from fiber composites. The technology of filament winding the flat oval shaped tube with high interlaminar shear and flexural strength has resulted in units capable of withstanding great depths while retaining a bending compliance nearly 100 times the compressibility of sea water. Unfortunately the price of the graphite fibers used in developing this statically rugged, acoustically soft tube is currently over $30/lb. This high price both restrains use of the new composite tubes and forces a search for less expensive materials as well as other tube shapes and/or tube-like concepts. One alternative material is S glass with a cost saving of 30 to 1, but possibly a trade of cost for some compliance in the cases where greater than (10)4 cycles of static loading are required. Alternative designs include multicomposite laminates, rectangular tubes with simple supports at the ends, strip loaded round tubes, corrugated tubing, and honeycomb tube configurations. This paper describes advantages and problems associated with each concept.
On maximizing peak insertion loss and bandwidth of compliant tube acoustic baffles
Authors: Brigham G. A. , Libuha J. J.
Published: October 2005

Compliant tube baffles have the insertion loss spectra of a mechanical band pass rejection filter. Peak loss occurs at the tube's flexural resonant frequency in the grating with a bandwidth proportional to tube compliance (i.e., average tube deformation), tube cross-sectional area, center to center spacing, and water/array inertial relative to tube inertia. Peak loss is logarithmically proportional to the ratio of tube mechanical Q in vacuo to array Q and is therefore maximum for minimum tube hysteresis and maximum array bandwidth. For uncompensated tubes the maximum bandwidth can be defined by first calculating the allowed wall thickness as a function of tubes stress to load ratio and midsurface eccentricity and then collating this with array geometry, spacing, and tube material. In this paper we present the variation of bending compliance, array bandwidth, ratio of interlaminar shear to flexural stress ratio, and peak loss curves with eccentricity. The optimum shape for a butted array of flat oval tubes using graphite fiber and S glass composites is determined and shown.
Comparative mammalian sound localization
Authors: Gourevitch George
Published: October 2005

The ability to locate sound in space differs considerably among terrestrial, nonecholocating mammals. Of those that have been investigated so far, none has matched man in this capacity. The diversity in the accuracy of localization by these mammals will be presented, and factors such as headsize and gross peripheral anatomy contributing to this variability will be discussed. In addition to external anatomy, more central portions of the auditory system also limit the exactness with which mammals can localize sound sources. This aspect of the binaural auditory system, examined in lateralization studies on the sensitivity to time and intensity disparities, will be presented. Finally, some remaining issues raised by a comparative approach to localization will be discussed.
Measurement of attack sequences of musicians playing in ensemble
Authors: Harkness E. L.
Published: October 2005

The paper will describe methods of measuring attack sequences of from 2 to 24 instrumentalists “attacking” at the same “instant.” In separating the attack sequences (a) of 2 or 3 instrumentalists, one-third octave filters were used; (b) of 12 instrumentalists, 1% bandwidth filters were used; and (c) of 24 instrumentalists, 3-Hz bandwidth filters were used. Separation of attack sequences was possible only by the instrumentalists playing notes within a spread of less than one octave. To separate the attack sequences of 12 instrumentalists, full tones and half tones were played. To separate the attack sequences of 24 instrumentalists, full tones, half tones, and quarter-tones were played; fixed pitch instruments played full tones and half tones, and stringed instruments played quarter-tones. The measured attack sequences were compared to each of the performer's subjective judgments of his or her accuracy of attack, and also compared to the conductor's assessment of the orchestra's cleanness of attack. In addition, the cleanness of attack was assessed by the orchestra listening to a recording of its own performance.
On the measurement of timbre dependence upon bowing technique
Authors: Downs Barbara , Parvulescu Antares
Published: October 2005

Experiments have sought to determine the spectral changes that can be reliably measured when various bowing techniques are used, by the same performer or by different performers. The trained musician can generally identify the technique (legato, staccato, “col legno,” upbow or downbow, ponticello, etc.) through the distinctive timbres. This study has been limited to the violin, and the complexities of the electronic analysis, as well as the partially meaningful results will be presented. The difficulties include the room reverberation characteristics, the directional radiation of sound from the instrument, and the variance of the individual repeat of a given note, even without the inter-performer variance. We carefully avoid inclusion of psycho-acoustic consideration.
Experimental data on “singer's formant”
Authors: Hollien Harry , Keister Elwood , Hollien Patricia A.
Published: October 2005

Confusion exists relative to the presence or absence of a singing-related “formant” in the phonatory output of individuals classified as artistic or premier singers. It has been suggested that this special formant occurs in the 3-kHz region and that it accounts for the “ring” reportedly perceived when such professionals sing. Four groups of ten males and ten females were studied in order to test this notion. They were equally divided into the groups as follows: (1) artistic level singers, (2) student singers, (3) nonsinger musicians, and (4) nonsingers. All subjects produced the vowel /u/ at nine intensity/frequency combinations. Two evaluation procedures were applied: long term spectral analysis (energy in the 2700–3400-Hz range as a function of total energy) and wave analysis (difference in dB between maximum peak and greatest peak in the 2850–3150-Hz range). Both sets of data resulted in similar trends with all results statistically significant. Evidence of a singer's formant was most pronounced in the phonatory output of the singers and to a lesser extent in the vocalizations by students; the effect was more apparent in males than in females. The presence of a “singer's formant” appeared to be functionally related to the higher frequencies and especially to conditions requiring greater amounts of vocal intensity.
Comparison of theoretical and measured sound levels behind barriers with ground
Authors: Isei T. , Embleton T. F. W. , Piercy J. E.
Published: October 2005

Small-scale experimental results outdoors over grass and asphalt surfaces using plywood barriers have been described previously [J. Acoust. Soc. Am. 63, S59(A) (1978)]. The systematic variations of sound level about the curve due to Maekawa were described qualitatively in terms of the interference between direct and ground-reflected waves on each side of the barrier, including the changes of phase on reflection at the ground for acoustically soft surfaces. These and similar results, for example where the source/receiver line is oblique to the barrier as well as perpendicular, are now compared quantitatively with calculations based on several alternate versions of theory—integration over the irradiated area above the barrier, integration over the surface of the barrier plus Babinet's principle, and integration along the edge of the barrier. (In general integration must be done numerically because known analytical forms do not allow correct evaluation of ground-reflected waves since their amplitude and phase depend on direction.) The agreement between prediction and measurement is good, both for the frequencies at which interference occurs and the sound levels throughout the interference spectrum.
A new integrating real-time analyzer
Authors: Allen D. S.
Published: October 2005

A new integrating real-time analyzer features true portability (40 lb), battery operation and a built-in scope display. It offers a new convenience for laboratory and field noise and vibration measurements. Frequency analysis in octave or 1/3-octave bands from 2.5 Hz to 20 kHz is complimented by a unique level versus time mode which allows display of A, flat or frequency band levels over up to 32 preselected measurement periods. For community noise analysis, up to 32 hourly Leq values can be displayed. The instrument will find wide application in industrial, community and product noise studies.
Nearfield measurement of the radiation impedance of a vibrating plate in a reverberant room
Authors: Hansen Colin H. , Bies David A.
Published: October 2005

An experimental procedure is described which allows both the resistive and reactive parts of the acoustic radiation efficiency of a resonantly vibrating surface to be determined. In addition the procedure allows the precise location of acoustic sources which radiate sound energy to the farfield. The method makes use of a continuous microphone scan in the nearfield of the vibrating surface to determine pressure, and a single acceleration measurement and a time-averaged hologram to determine velocity. The information recorded in computer memory is used to determine the local complex acoustic intensity at each pressure measurement point on the vibrating surface. The experimental procedure is applied to the investigation of the effect of a rotating diffuser on the instantaneous radiation impedance presented to a resonantly vibrating plate located in a reverberant room.
Acoustic emission arising from plastic deformation and fracture
Authors: Ono Kanji
Published: October 2005

This paper reviews diverse observations of acoustic emission from materials and attempts to interpret them on the basis of current knowledge of plastic deformation and fracture. An attempt is made to unify diverse and often conflicting findings paying special attention to microstructural conditions. Observed acoustic emission characteristics have been classified according to their probable origins such as heterogeneous and homogeneous yielding, dynamic strain aging, twinning, decoheston and fracture of second phase particles, and deformation-induced transformation. Temperature effects and sources of burst-type emissions are considered. The micro-yielding concept and other mechanisms are correlated to various acoustic emission behavior observed. Fracture processes generally produce high levels of acoustic emission. Various fracture mechanisms found in different classes of materials are correlated to observed acoustic emission behavior. Relationships between different AE parameters and stress intensity factor or crack tip opening displacement are discussed. It is shown that the consideration of second phase particles is of crucial importance in identifying the mechanisms of acoustic emission. [Work supported by ONR.]
Deformation and failure information from composite materials via acoustic emission
Authors: Hamstad M. A.
Published: October 2005

An introductory literature review of the applications of acoustic emission (AE) to the study of composite materials and structures is given. This survey demonstrates the unique information that AE provides on the deformation and fracture processes which occur when composite materials are stressed. Also included in the review is a survey of the application of AE to nondestructive testing of composite materials. Following the review, new research results are presented in some areas of current research interest. The following areas are emphasized: (1) Wave propagation complications and the development of AE source location techniques in Kevlar 49/Epoxy composite pressure vessels; (2) evaluation of a special immersion type AE transducer; (3) study of couplants for AE testing of composites; and (4) application of AE to the study of a Boron/Aluminum particulate composite. [Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore Laboratory under contract No. W-7405-ENG-48.]
Evidence for mechanisms of ultrasonic attenuation in tissue derived from measurements on myocardium
Authors: Miller J. G. , O'Donnell M. , Mimbs J. W.
Published: October 2005

Although reports have suggested that protein content, especially collagen content, may be a significant determinant of the acoustic properties of soft tissue, the responsible mechanisms have not been established. Two classes of mechanisms have been considered: (1) structural, conformational, or chemical relaxations of the macromolecular constituents, and (2) processes arising from the inhomogeneous nature of tissue, such as viscous relative motion. As an approach toward identifying the mechanisms, the present investigations address quantitatively the relationship between the ultrasonic attenuation and certain physical properties of myocardial tissue. Myocardial infarction provides a method for investigating the relationship between collagen content and the ultrasonic attenuation, since increased concentration of collagen has been reported in areas of infarct. Collagen concentration was determined quantitatively using an assay for hydroxyproline. Measurements were conducted in vitro on approximately 900 sites from 60 dogs. The dependence of the ultrasonic attenuation on frequency and temperature, as well as on collagen concentration, was investigated to provide evidence of the mechanisms responsible for the attenuation.
Temperature dependence of the velocity of sound in suspensions of erythrocytes
Authors: Rooney J. A. , McAlister G. B.
Published: October 2005

Measurements of the velocity of sound in suspensions of human erythrocytes were made using a Panametrics 5054 ultrasonic time intervalometer. Data was taken using the pulse echo overlap method for sound velocity at a frequency of 2.25 MHz. The erythrocyte suspensions had a hematocrit of 45% and were made using either 0.75, 0.9, or 1.1% saline solutions. The erythrocyte samples were placed in a chamber maintained at a specified temperature for 10 min to allow thermal equilibrium to be reached and stirred throughout the measurement procedure. The velocity measurements were made by having the pulse of sound pass through a buffer region and observing the echoes received from the front and rear interfaces of the sample chamber as well as a target rod placed in the chamber. For all suspensions studied the velocity of sound increases in a nonlinear manner by about 40 m/s in the temperature range from 25° to 60°C. Details of this variation depend upon the suspending medium and age of the cells. [This work was supported in part by the National Science Foundation.]
Biomedical ultrasonic imaging at SRI International
Authors: Suarez J. , Buxton J. , Green P. , Holzemer J. , Ramsey S. D. , Wilson D.
Published: October 2005

Three different real-time imaging systems for medical diagnosis have been developed at SRI. The first is a transmission C-scan system operating at 2 MHz. This system uses a 192-element linear receiving array, a 28 element diffuse illumination source, and a lens/deflector package to produce an orthographic image of a field approximately 15 cm on a side. The second is a 10 MHz B-scan system designed to visualize atherosclerotic plaque in the carotid arteries. An area 3 cm wide by 3 cm deep is imaged with the mechanically scanned and dynamically focused transducer. The third system, designed for detection of pancreatic cancers, is a 10-M Hz B-scanner that incorporates a miniaturized 64-element linear array in the tip of an endoscope. Scanning and focusing on both transmit and receive are accomplished by appropriate grouping and phasing of array elements. This system images an area 3 cm wide by 4 cm deep. The principles of operation of each system are discussed and a movie showing representative images made with each of the systems is presented. [Work supported by NIH.]
Acoustic phonetic word recognition
Authors: Jones B. L. , Garrett B. L. , Rayne M. A. , Gerber S. E. , Malecot A.
Published: October 2005

The ability of listeners to identify specific words in known and unknown languages using only acoustic information was examined. Each of ten listeners (representing eight different languages) listened to eight passages of fluent dialog, including one in his primary language and one in English (a secondary language for eight listeners). The average number of accurate identifications was slightly more than 50% with nearly 30% of responses being false positive. Word-spotting ability varied widely and appeared to be language dependent, it also appeared to be subject dependent, but the language background of a subject did not affect his ability. Phonetic transcriptions of passages containing false alarm responses revealed that, in unknown languages, false positive responses often appeared to be elicited by utterances that were phonetically similar to the target word. In known languages, semantic similarity was the eliciting factor. Although the average subject's word-spotting ability was better in a known language than an unknown language, the most efficient word-spotters performed better in some unknown languages than the native speakers of that language.
Two useful techniques for automatic speech recognition
Authors: Coker C. H.
Published: October 2005

We describe two quite separate techniques that can enhance the performance of automatic speech recognition. One is a procedure that, in most task domains, will very significantly restrict the combinatoric explosion of possible interpretations. The other is a metric and a method for optimizing that metric for the discrimination of very similar words (diphones or other tokens). Two traditional paradigms that are similar to desirable properties of speech recognition are medical diagnosis and biological classification. In both fields, the procedures are to use rather simple methods to narrow the search to a few very similar choices, and then to perform specific tests that are optimum to discriminate these specific cases. We describe a technique that will automatically optimize a distance metric to give the best performance in differentiating a vocabulary item from its most confusable neighbors.
Plosive detection and segmentation using the Adaptive Lattice Linear Prediction algorithm
Authors: Carter T. E.
Published: October 2005

A new approach to acoustic segmentation of speech has been developed and incorporated into a plosive detection algorithm. The technique uses a measure of fast spectral change derived from the Adaptive Lattice Linear Prediction (ALLP) algorithm, a speech processing technique based on the least mean square gradient adaptation method [T. E. Carter, IEEE ICASSP-78 Conference Record, 27–30 (1978)]. This measure can be formed from the inherent disparity created between the forward and backward prediction coefficients of the ALLP algorithm during these transitions. Good time resolution is achieved because the filter coefficients are computed on a sample basis. A plosive detection algorithm utilizing this spectral measure with additional acoustic-phonetic information has been designed and tested. It may also be possible to perform acoustic segmentation of speech by marking segment boundaries at points of significant spectral change. Details and experimental results will be discussed.
Influence of vocalic context on perception of the [s]-[∫] distinction
Authors: Repp Bruno H. , Mann Virginia A.
Published: October 2005

Kunisaki and Fujisaki [Ann. Bull. RILP 11, 85–91 (1977)] have reported that perception of fricatives from a synthetic [s]-[∫] continuum depends on the nature of the following vowel: Listeners give more [s] responses when the vowel is rounded than when it is unrounded. After replicating their basic finding using 100-ms fricative noises followed by either [a] or [u] (with appropriate formant transitions), we have begun to investigate the limits of this contextual dependency. Our experimental manipulations include (1) extending the duration of the fricative noise, (2) introducing silent intervals of varying length between the fricative noise and the vocalic portion (so that a fricative-stop-vowel sequence is heard), and (3) preceding the fricative-stop-vowel stimuli with another vowel (thereby introducing a syllable boundary between the fricative and the stop). We have also preceded and/or followed the fricative noises with steady-state vowels, and we have systematically varied the formant transitions of the following vowel, in order to dissociate contextual effects due to the transitions themselves from those due to the vowel. By comparing our perceptual results with measurements of natural speech, we will examine to which extent contextual dependencies in perception (and their changes in the various experimental conditions) parallel coarticulation effects in the production of analogous utterances. [Work supported by NICHD and BRSG.]
Influence of preceding [s] or [∫] on stop consonant perception
Authors: Mann Virginia A. , Repp Bruno H.
Published: October 2005

The category boundaries on synthetic [da]-[ga] and [du]-[gu] continua are shifted substantially when the syllables are preceded by one of the two synthetic fricatives, [s] or [∫]: More velar stops are heard following [s] than following [∫]. We have investigated how this contextual dependency changes as (1) the silent closure period following the fricative is extended, and as (2) the fricative is preceded by a vowel to create a syllable boundary between fricative and stop. Preliminary data indicate that, while neither manipulation completely removes the contextual effect, both cause a reduction in its size. We suppose that the context dependency reflects the dynamics of speech production. Fricative-induced shifts in stop consonant category boundaries presumably correspond to coarticulatory shifts in the precise place of contact between tongue and palate. We expect to obtain measurements on natural speech that bear on this hypothesis. [Work supported by NICHD and BRSG.]
Contralateral cueing effects in the perception of aspirated stop consonants
Authors: Pastore Richard E.
Published: October 2005

Backward making has been conjectured to be one possible acoustic factor determining the category boundary for voiceless stop consonants in CV syllables. Recent research from our laboratory has shown that contralateral cues providing timing information about the signal to be detected improved the detectability of monaural tonal signals in backward masking situations, but not in either simultaneous or forward masking situations [Puleo and Pastore, J. Acoust. Soc. Am. 62, S25(A) (1977)]. We therefore employed this technique to investigate the perception of the aspirated stop consonant-vowel syllable /pa/. Both tonal and noise cues providing timing information to the earphone contralateral to the signal earphone altered performance in the predicted manner. Under certain conditions the Gaussian noise cue also altered the perceived phonetic category from /pa/ to /ta/. [This research was conducted while the author was visiting Haskins Laboratories and was supported by BRS Grant RR-05596 to Haskins Laboratories.]
Detection of nasals using a production model
Authors: Shirai K. , Gomi T.
Published: October 2005

An important task in speech recognition is to detect nasal or nasalized sounds. In this paper, this problem is considered in the framework of an articulatory model. In this model, the position of the articulatory mechanism is expressed by six parameters containing a nasalization parameter XN which expresses the position of the velum. The transfer function of the vocal tract with a side branch was obtained from Kelly's ladder equivalent circuit. Two kinds of production models were prepared depending on whether the nasal output was dominant or not when compared with the oral output. The estimation was performed under criteria which minimized the spectral error. Isolated nasalized vowels and continuous speech including nasal consonants were analyzed. In both cases, the nasalization parameter XN was proved to be useful for the detection of nasal sounds. While all the articulatory parameters can be estimated rather successfully in the case of nasalized vowels, the method is not sufficient for discriminating /m/ and /n/ completely in continuous speech.
Vowel normalization by frequency warping
Authors: Matsumoto H. , Wakita H.
Published: October 2005

Normalizations of formant frequencies have frequently been used to eliminate inter-speaker differences in vowel identification. However, estimation of formant frequencies become difficult under certain circumstances. This paper proposes a new approach to vowel normalization based on a frequency warped spectral matching. A frequency normalized distance between test and reference spectra is defined on the basis of the minimum mean square difference over all possible choices of frequency warping functions. The warping functions are constrained so that they mostly take account of linear scaling for the differences in vocal-tract lengths and of slight nonlinear differences. The slope of the warping function is restricted by an assumed range of the vocal-tract length. After adaptively eliminating the individual glottal characteristics, the spectral distance is computed by means of dynamic programing. A preliminary experiment indicates a substantial improvement in identifying female steady-state vowels when male vowels are used as references. The vocal-tract length can also be estimated from the slope of the warping function.