bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrasonic studies of high-Tc superconductors
Authors: Horie Yuuji , Terashi Yuichiro , Fukuda Hiroshi , Hidaka Masanori , Fukami Takeshi , Mase Shoichi
Published: October 2005

High-Tc oxide superconductors [MBa2Cu3O7 (M = Y and lanthanoids), (La1−xSrx)2CuO4, BaPb1−xBixO3, x < 0.35] and their related insulating oxides [MBa2Cu3O6, BaPb1−xBixO3, x > 0.35] were investigated by means of ultrasonic measurements. By using sound waves of f0 = 10 MHz, we observed several peaks in the curves of the attenuation coefficient α(T) versus the temperature T for the superconducting samples. These peaks can be attributed to sound energy dissipation accompanied by excitations in optical phonons. However, there was no obvious anomaly near Tc except for BaPb0.8Bi0.2O3 with f0∼30 MHz. The electronic contribution to α(T) was estimated to be very small in the Pippard mechanism of attenuation because of low electrical conductivity and a low f0. In order to increase f0, measurements with single-crystal samples having smaller resistivity are in progress. On the other hand, in the insulating samples, there are several peaks in the α(T) versus the T curves that can be assigned to some structural modulation. This assignment is supported by these piezoelectric and capacitance measurements. On the basis of these experimental results, the phonon contributions to high-Tc superconductivity are discussed.
Acoustic correlates of apical and laminal articulations
Authors: Dart Sarah N.
Published: October 2005

Several indigenous languages of the western United States have a phonemic contrast between segments articulated with the apex of the tongue up (apical) and those articulated with the apex down behind the lower teeth and the contact on the palate made instead with the blade of the tongue (laminal). This difference in apical and laminal articulation is also seen in individual variation in languages without such a phonemic distinction. In the present study, palatograms and linguagrams with synchronous audio recordings were taken of a number of speakers of French, American English, and several different Native American languages, illustrating apical and laminal articulations in languages both with and without the pertinent phonemic distinction. The segments studied include /t,d,n,l,s,z/. This paper reports on the acoustic correlates of the articulatory differences found within each language as well as some cross-language comparisons. [Work supported by NSF Grant BNS 8704361.]
Acoustic differences correlated with derivational history
Authors: Peet M. , Withgott M.
Published: October 2005

In a study of American English palatals, acoustic characteristics of allophones with different derivational histories were compared. In examples such as “toss sheepskins” versus “josh Sheila,” palatalization was found to be complete, as observed in a spectral analysis, and no rearticulation was found. However, the š derived from a sequence of two š's was observed to exhibit longer duration values than the s from an sš sequence, in keeping with the underlying, intrinsic segment duration values (cf. also, Zue and Shattuck-Hufnagel, 1980). The results suggest that a production/perception theory should model the underlying segment along with the assimilation process. The data were collected from a corpus of 60 sentences each read by eight adult male speakers. [Work supported, in part, by DARPA-ISTO.]
Aerodynamic constraints on language history: The ease of bilabial trills
Authors: Maddieson Ian
Published: October 2005

Bilabial trills, transcribed [B], are markedly rare as speech sounds in the world's languages, even though Catford (1977) claims that they are the easiest type of trill to produce. With one exception (Liangshang Yi), all languages known to have bilabial trills developed them in a highly restricted environment consisting (historically) of a sequence of a voiced bilabial nasal, a voiced bilabial stop, and a high rounded vowel, e.g., [mbu] → [mBu]. In many cases, the trill remains allophonic (e.g., Na?ahai, Windua) but some languages have undergone a restructuring resulting in phonemic bilabial trills (e.g., Kurti, Atchin). The limitation to this environment suggests that aerodynamic conditions normally only satisfied in speech by this sequence are required for labial trilling to develop. The essentials would seem to be: (1) transglottal airflow without intraoral pressure buildup, permitted by the nasal escape in [m] and not significantly affected by the very brief closure typically found for a homorganic post-nasal stop; (2) subsequent maintenance of bilabial closure without nasal flow, providing for an oral release; and (3) a following vowel with a target position for the lips of narrow aperture. Since this target lip position requires only a small movement from closure, articulatot movement is slow [Kent and Moll (1972)]; hence, there is a period of time during which the lips remain close enough together for Bernouilli forces, in the absence of increased intraoral pressure, to reclose them and initiate trilling. A simplified quantitative model of this process will be presented, together with speculations on why bilabial trills do not otherwise occur linguistically. [Research supported by NSF Grant BNS 87-20098.]
An acoustic analysis of English liquids uttered by the Japanese and native speakers of English
Authors: Nakashima Hirotake , Nakayama Yukihiro , McHugh Charles
Published: October 2005

This research deals with the production of English liquids through an acoustic analysis of speech samples uttered by Japanese college students, advanced Japanese learners of English (college teachers of English), and native speakers of English 13–18 years of age who live in Japan. The speech samples are 64 English words with liquids in initial position. These speech samples were analyzed by the autocorrelation method of linear prediction to estimate the formant frequencies every 10 ms using an analysis window of 20-ms length. The second and third formant frequencies were extracted for each of the liquids. The results showed that: (i) There is a significant difference in the formant values of each liquid between males and females; (2) the formant values of each liquid for advanced Japanese learners of English coincide with those for native speakers of English; and (3) although the values of F2 and F3 of /r/ and /l/ uttered by Japanese students overlapped with each other on the F2-F3 plane, these separated clearly after pronunciation training.
Infants' vocalizations in mother-infant interaction
Authors: Shimura Yoko , Imaizumi Satoshi , Ichijima Tamiko , Saito Kozue
Published: October 2005

The vocal behavior of young infants was investigated to clarify the process of speech acquisition. Acoustic and picture analyses were carried out for audio and video recordings of 26 young infants (aged 4 to 19 months) being addressed by their mothers, unfamiliar adults, or voices presented through a loudspeaker. The results were the following. (1) Mothers tended to use a wider range of F0 than those observed in their speech toward adults. (2) The F0 upper limits in the mothers' speech was closely related to the F0 of their infants' voices. (3) Young infants produced various voice qualities, which could be characterized by the richness of their subharmonics, the richness of noise, or a sudden change in F0. (4) Not only the qualities of the infants' voices, but also their facial expressions and looking behavior seemed to change according to how and by whom they were being addressed. [Work supported by Toyota Foundation.]
Phonologically motivated substitutions in a 20–22 month old's imitations of intervocalic alveolar stops
Authors: Best Catherine T. , Wilkenfeld Deborah
Published: October 2005

Systematic deviations between early word productions and their adult targets reflect not only children's articulatory limitations, but also their phonological development. However, research in child phonology has overlooked an important source of information by excluding from analysis any direct imitations of adult words. Consistent with observations about syntactic and cognitive development, spoken imitations should be systematically modified by the child's phonological system. Imitation studies should thus reveal more about the sophistication of the early phonological system by minimizing demands on memory and lexical access, by allowing presentation of unfamiliar or nonsense words, and by permitting comparison of the child's productions with the actual phonetic and acoustic properties of the adult targets. The present research found remarkable phonological sophistication in a toddler's production of intervocalic stops, based on phonetic and acoustic analyses of her imitations of a set of phonetically reduced adult targets at 20–22 months of age. The adult targets were disyllabic words and nonwords containing /d/ or /t/ preceding 〈-er〉, 〈-le〉, or 〈-en〉, in which the stops were realized as the restricted phonetic variants [r], [dn], or [ʔ], (e.g., respectively, 〈wider〉 or 〈whiter〉; 〈widen〉; 〈whiten〉). Although alveolar stops are not normally produced in this phonetic environment, the child consistently substituted them for the more restricted variants found in the adult targets. The child's phonology also distinguished /t/ and /d/. The findings indicate a rule like that in the adult grammar which determines how these phonemes will be realized in highly specified phonetic contexts and, consequently, how phonetically disparate forms are related in an abstract category. The child's failure to exactly imitate the target utterances and the systematicity of her deviations further argue that the targets were, in fact, filtered through the child's phonology before she produced them. [Work supported by NIH.]
Fricative consonants: Comparisons between human and mechanical-model production
Authors: Shadle Christine H.
Published: October 2005

In an earlier paper [C. Shadle, J. Acoust. Soc. Am. Suppl. 1 82, S15 (1987)], the derivation of source parameters for fricative consonants from mechanical models of the vocal tract was discussed. Source location and source spectrum at a range of airflows were measured for the fricatives /∫, ç, x/, and the separation of these fricatives into two distinct acoustic types was proposed. This paper presents further analysis of these data. A collapsing of the source spectra into a single curve for each fricative, parametrized by flow rate, is proposed. These collapsed source characteristics were used in a frequency-domain model of the vocal tract [P. Badin and G. Fant, STL-QPSR 2–3, 53–108 (1984)] to predict the farfield sound generated. These predicted spectra were compared to the sound produced by the mechanical models and by Fant's subject on which the models were based. Some discrepancies between experiment and theory are apparent; these are due to the lack of higher modes in the computer model, some slight anatomical inaccuracies in the mechanical model in the region of the constriction, and probably also to spatial distribution of the source for /ç,x/. Aside from these discrepancies, the comparison demonstrates the validity and usefulness of the mechanical-model data.
The basics of flow noise
Authors: Skudrzyk Eugen J.
Published: October 2005

The flow noise nearfield that is recorded by a flush-mounted hydrophone is generated by a “Bernoulli” effect. Because the pressure within the eddies is less than that in the fluid outside, fluid is injected into the eddies and thrown against the wall. The kinetic pressure is then recorded as nearfield noise. The nearfield sensitivity of a hydrophone seems to depend greatly on its shape and size. But a closer investigation shows that its sensitivity is inversely proportional to its extension in the direction of the flow and is approximately independent of its width. At high frequencies, the radiation field dominates over the nearfield. The radiation field is described by the Lighthill equation. Its left-hand side is identical with the wave equation for an inviscid fluid; on the right, turbulence-generating effects are accounted for by a known “forcing function.” For a point force, the solution is an image source supplemented by a thin layer of evanescent shear waves along the boundary. A similar solution is obtained for multipoles and for turbulence. There is no layer of sound-radiating dipoles nor a resonance board effect, as is proved by performing the computation in terms of the Fourier amplitudes.
Generation of discrete frequency noise due to periodic vortex shedding from a streamlined body
Authors: Fukano Tohru
Published: October 2005

The mechanism of discrete frequency noise generated from a flat plate with a sharp trailing edge immersed in a uniform oncoming flow was investigated experimentally. The results show that discrete frequency noise is caused by the periodic shedding of Karman vortices, and the necessary conditions of its generation are summarized as follows: (1) There must be a dead flow region with a definite area of a sufficiently large scale. (2) The shear layers starting from the two separation points near the trailing edge of the body must be very strong on either or both sides of the plate. A flow model was introduced to estimate the sound-pressure level theoretically and was verified experimentally as useful. The characteristics of Karman vortex shedding from a rotating blade were also examined.
Control of Karman-vortex sound by two crossing cylinders
Authors: Maruta Yoshiyuki , Suzuki Shoji
Published: October 2005

The pure tone generated from a cylinder's wake with a Karman vortex in the airflow is the basic phenomenon of aerodynamic sound and is also the sound that is often generated by flows of wind around constructions and the inner flow of turbomachinery. By putting another crossing cylinder into contact with the first, the Karman-vortex sound becomes quieter than for a single cylinder [Maruta et al., Proc. Internoise 87, 481–484 (1987)]. This phenomenon was investigated experimentally by changing the diameters, space, and crossing angle between the two cylinders. For cylinders with the same diameter, normal crossing was more effective for this sound reduction. For the ones with different diameters, inclined crossing was more effective with space less than 1.5 times the upstream cylinder's diameter. The sound reduction results from the fact that the spanwise coherence of the Karman vortex from the upstream cylinder is prevented by crossing with other cylinders. The Karman-vortex sound can be controlled by the optimum condition of two crossing cylinders.
The response of plates to TBL excitation: High versus low wavenumber effects
Authors: Martin Nathan C.
Published: October 2005

Structural response to turbulent boundary layer (TBL) wall pressure fluctuations has been recognized as an important consideration in the design of aircraft and ships for many years. Unlike most sources of structural response, the TBL generates fluctuating pressure components over a wide range of spatial (i.e., wavenumber) as well as temporal (i.e., frequency) scales. In the frequency range of interest for many applications, the dominant spatial components of TBL excitation lie at relatively high wavenumbers compared to the major acceptance regions of resonant structural modes. Chandiramani [J. Acoust. Soc. Am. 61, 1460 (1977)] has shown that the low wavenumber components of TBL excitation dominate the response of plates with simply supported boundary conditions when certain assumptions are made about the relative levels of TBL high and low wavenumber content. The purpose of this paper is to re-examine the subject of the relative importance of high and low wavenumber contributions to TBL-excited plate response as influenced by potential variables such as the various models of TBL wavenumber content and the nature of the plate boundary conditions.
Design considerations for reducing propeller cavitation noise
Authors: Hoshino Tetsuji , Sasajima Takao , Oshima Akira
Published: October 2005

In designing naval or oceanographic ships, the reduction of underwater noise radiated from the ship is of primary importance to secure the reliable operation of acoustic instruments. Among various hydrodynamic and mechanical noise sources, propeller cavitation is considered to be most harmful for acoustic survey operation. A design for low-noise propellers and design examples for oceanographic research ships are presented. The cavitation patterns and radiated noise characteristics of the propellers thus designed were investigated by model tests in a cavitation tunnel. It was shown that the radiated noise level from the propeller was sufficiently low in the model scale. This was further confirmed by radiated noise measurements on the propeller at full scale. The comparison of the full-scale noise data with those estimated from the model scale noise data showed that the noise measurements in a cavitation tunnel are useful in evaluating the design of a low-noise propeller.
Laser Doppler vibrometer technique for measuring surface waves produced on submerged elastomeric layers
Authors: McDevitt Timothy E. , Stuart Alan D.
Published: October 2005

A dual-channel, combination vibrometer/velocimeter laser Doppler system has been developed to measure the surface waves produced on a submerged elastomeric layer excited mechanically or by a fluid flow. This nonintrusive laser system permits velocity measurements to be made both normal and in the plane of the layer's surface without distorting its vibratory field. Since two laser systems are employed, measurements can be made simultaneously in two locations: permitting the spatial coherence of the surface disturbance to be assessed and transfer functions between source and response to be determined. This paper will present the results obtained for a long sample of elastomeric material submerged in water, and driven both longitudinally and in flexure to simulate typical in-plane and transverse motion of its surface. [Work supported by ONR.]
Acoustic concepts in nonuniform, steady potential flows
Authors: Campos L. M. B. C.
Published: October 2005

The concepts of Doppler factor, local Doppler-shifted frequency, Blikhintsev wave invariant, and group velocity, which are well known for sound in a uniformly moving medium, and in the ray approximation to the acoustics of nonuniform flows, are generalized to waves of arbitrary frequency in a steady, nonuniform potential flow of arbitrary Mach number. The generalized concepts coincide with the usual Doppler factor, local frequency, wave invariant, and group velocity, in the ray approximation, and their definition is made unique by the requirement that, outside the ray approximation, the following relations remain valid: (i) The generalized wave invariant remains an adiabatic invariant, in the sense that it equals the total (kinetic plus compression) energy divided by local frequency; (ii) the latter is related to the wave frequency through the generalized Doppler factor; (iii) the energy velocity is the ratio of energy flux to energy density. All these concepts depend on convection and energy partition factors, which reduce to unity in the ray limit. These concepts are introduced on the basis of the acoustic energy equation, which can be derived from a variational principle, which also yields wave equations.
Wall pressure fluctuations in the transition region
Authors: Galib Thomas A.
Published: October 2005

Wall pressure fluctuations on an axisymmetric body of revolution were measured with piezoelectric pressure transducers. Spectral analysis of the data showed discrete frequency bands of the pressure fluctuations corresponding to predicted Tollmien-Schlichting disturbance frequencies in the transitional boundary layer. Nondimensional power spectra showed that the peaks of the disturbance frequencies (for three free-stream velocities) collapsed to a single Strouhal number. Further manipulation of this result yielded an expression for the Tollmien-Schlichting frequencies in terms of a constant and the displacement thickness Reynolds number. These results were for a near-zero pressure gradient. They were later reproduced in an adverse pressure gradient for a variety of Reynold's numbers.
Vibroacoustic analysis of a space shuttle payload
Authors: Lee Y. Albert
Published: October 2005

A Vibroacoustic payload environment prediction system (VAPEPS) has been developed to perform statistical energy analysis of spacecraft under acoustic excitation. VAPEPS was employed to analyze the random vibration response of the NASA Office of Space Science-1 (USS-1 Payload in the space shuttle cargo bay acoustic environment. The OSS-1 payload consists of various experimental hardwares mounted on a pallet. The pallet is constructed of a framework covered with face panels that is responsive to the acoustic pressure field. The entire pallet structure was modeled as an equivalent plate with the same dimension, stiffness, surface mass density, and longitudinal wavespeed. Detailed models were also constructed of the individual panels of honeycomb construction, which make up the overall face panels. The predicted acceleration power spectral density in third octave bands was compared with experimental data measured at system level acoustic test in a reverberant chamber. The agreement is good.
Radiated sound-pressure levels and sound source locations on the German ICE high-speed train
Authors: Pfizenmaier E. , King W. F. , Lettmann H. , Barsikow B.
Published: October 2005

The German ICE high-speed train demonstrated on 1 May 1988 that speeds up to 406 km/h can be attained using conventional wheel/rail technology. High-speed railway vehicles such as the ICE generate strong aerodynamic sound sources that overwhelm the noise contribution produced by wheel/rail interaction, particularly when the wheels have been acoustically treated. If radiated noise levels are to be held to a minimum, the aerodynamic characteristics of such vehicles have to be optimized. The ICE has been designed in this way. Sound-source location measurements were carried out using a line array of 15 microphones positioned along the wayside. The first results of this study will be discussed in the present paper for train speeds up to 300 km/h. Wayside noise measurements made during the record-breaking run on 1 May 1988, when a speed of 406.9 km/h was attained, are also presented. The aerodynamic component of radiated noise is separated from that due to wheel/rail interactions, and the resulting analysis is shown to be also applicable to maglev vehicles. Also at Technische Universität Berlin, Inst. füt Techn. Akustik.
Mechanoelectrical transduction of the chick hair cell
Authors: Ohmori Harunori
Published: October 2005

Hair cells transduce mechanical energy applied to the apical hair bundle into an electrical signal, i.e., the transduction potential, through gating of mechanically gated ion channels (m-e.t. channel). The gate demonstrates sigmoidal displacement versus response relationship irrespective of the variation in the hair bundle's length (from 7 to 30μm), as long as the stimulus is applied to the hair bundle at a fixed height from its insertion into the apical surface of the cell. The angular displacement of the hair bundle could therefore be a primary factor that determines the gating of the m-e.t. channel. The channel demonstrates strong selectivity to divalent cations, particularly to Ca ions, over monovalent cations. Mn is one of the permeants through the channel. Fura-2 fluorescence is modified by Ca and Mn ions permeated through m-e.t. channel, and these ions produce a localized peak and a localized depression, respectively, in the 340/380-nm fluorescence ratio images during mechanical stimulation in the vicinity of the hair bundle's insertion into the apical surface of the cell. This might be indicating the site of the mechanoelectrical transduction.
Acoustic transmission across the water/sediment interface
Authors: Satkowiak L. J. , Williams K. L.
Published: October 2005

Two sets of measurements were made to investigate the effect of the water/sediment interface on a propagating acoustic signal. In the first experiment, at-sea measurements utilized a three-dimensional array of hydrophones buried in the sediment as acoustic receivers. A linear acoustic source was mounted on a moveable tower located on the seafloor. The sound-pressure levels were measured as a function of grazing angle, frequency, and pulse shape for two distinctly different sediment types, fine sand and soft mud. The second set of measurements was made under nearly laboratory conditions. Data were collected mapping out the sound-pressure field in a homogeneous sand for both linear and parametric sources operating at a frequency of 20 kHz. The data were taken at grazing angles that ranged from well-above to well-below the critical angle for the sediment. Based on the data collected, in-sediment pressure field contours were obtained detailing the structure of the pressure field in the sediment. Both sets of data were compared with theoretical predictions calculated using the SAFARI model [H. Schmidt and F. B. Jensen, J. Acoust. Soc. Am. 77, 813–825 (1985)]. A discussion of the applicability of the SAFARI model will be presented.
High-frequency acoustics bottom interaction
Authors: Boehme Hollis , Chotiros Nicholas P.
Published: October 2005

Over the past half century, a large amount of bottom interaction data has been collected by the scientific community. From a comparison of the extant high-frequency backscattering strength data, it is clear that the current schemes of bottom type classification, based on textural descriptions of the geology, make poor indicators of scattering strength. Recently obtained results suggest that bottom topography is as important as composition. The topography of the ocean bottom, in turn, is partly determined by oceanographic processes, such as currents and tides. Thus a new set of descriptors is evolving that will give better indications of bottom backscattering strength. Topography also exerts a strong influence on acoustic transmission through the interface. The effects include scattering and deformation of the wave front.
A review of high-frequency acoustic boundary scattering prior to 1982
Authors: Farwell Robert W.
Published: October 2005

High-frequency acoustic sea surface and ocean floor scattering have attracted much attention from underwater acousticians over the past 50 years. In keeping with evolving system needs, the level of knowledge required from scattered signal characteristics has expanded. Many of these issues arc currently being addressed. This paper will review the status of high-frequency acoustic boundary scattering measurements and models above 10 kHz. Both forward and backscatter strengths, coherences, higher-order statistical characterizations, as well as supporting environmental measurements, will be presented.
High-frequency sea surface scattering measurements
Authors: Roderick W. I. , Chester J. B.
Published: October 2005

Measurement and modeling of forward and backscatter from the sea surface are important areas of study in high-frequency acoustics. To validate acoustic scattering models that involve reradiation from the surface and near-surface volume scatterers (e.g., bubbles, biologies), acoustic measurement techniques are required that isolate the scattering mechanisms from multipath effects. In this paper, results from surface scattering measurements that obtained reverberation as a function of grazing angle utilizing both parametric and conventional projectors are presented. Measurements were conducted in shallow waters and the directivity properties of the parametric array isolated the surface scattered path. In the study of surface forward scatter, a new technique has been developed that allows separation of surface scatter and direct path by forming a vertical virtual aperture. This technique may be useful in situations where time resolution (bandwidth) is not sufficient. In terms of reverberation, surface scattering strength measured as a function of grazing angle (in 10-deg increments) will be presented for two different sea state conditions. Also, low grazing angle Doppler shift and spread will be shown as a function of up-wind and cross-wind conditions. These results were obtained in measurements conducted in the shallow waters east of Jacksonville, Florida.
Observations of weak scattering during AATE
Authors: Ewart Terry E. , Reynolds Steve
Published: October 2005

Under ice measurements of acoustic phase and amplitude were made in the Beaufort Sea during April 1985 in the AIWEX acoustic transmission experiment (AATE). Pulses of 2, 4, 8, and 16 kHz were sent every 0.49152 s over a 6.4-km path between a moored transmitter and a depth cycling receiver array. The receiving aperture covered 153 m during down cycles that were repeated every 4.8 min for 12 days. The observations exhibit levels of intensity scintillation much weaker than those observed in the open ocean. At the lower frequencies, the scintillation levels are representative of statistics predicted by Born or Rytov theory. Measurements made of the internal wave field by AIWEX investigators exhibit fluctuations a factor of 10 to 20 below those observed in the open ocean. The observed travel time fluctuations and second and fourth moments of the field are consistent with predictions made using the observed environmental statistics. Tests comparing variations in time with the vertical variability have been made.
Laboratory and field measurements of acoustic scattering from sea ice
Authors: Jezek K. C. , Stanton T. K. , Gow A. J. , Lange M.
Published: October 2005

The morphology of sea ice growing thermodynamically in calm seas is complicated. The ice is characterized by temperature and salinity gradients that are driven by the prevailing oceanic and atmospheric conditions, the gradients, in turn, affecting physical properties such as permeability, porosity, liquid brine content, and the structure of the ice-water interface. That interface, in particular, exhibits a range of dynamic characteristics from submillimeter, pure ice dendrites that grow down into the liquid to smoother cellular structures that are believed to develop when either thermodynamic growth is slowed or when the salinity of the liquid is much reduced. The objective of the work presented here is to measure and understand the role changing ice morphology has on the acoustic properties of sea ice. To that end, measurements over the frequency band from 120 to 800 kHz have been made of the scattering properties of sea ice when insonified by a narrow beam at normal incidence. Observations made in an outdoor tank at CRREL and from the research vessel Polarstern, which operated in the Fram Straits during May 1988, reveal that the reflection coefficient can vary by at least a factor of 5 depending on the composition and structure of the ice near the ice/water boundary. The dendritic interface typical of growing sea ice plays a particularly important role resulting in improved acoustic coupling into the ice. As seasonal evolution changes the interface from dendritic to either cellular or ablating, the reflection coefficient rises to about 0.25. [Work supported by ONR and the Alfred Wegener Institute.]
Evaluation of an electronically focused multipulse imaging system
Authors: Miller A. P. , Harrold S. O. , Reeves J. M.
Published: October 2005

The scan rate of electronically focused imaging systems is dependent on three factors: the time for the electronics to create the transmit transducer energizing pulses, the ultrasonic propagation time, and the time to produce an image from the received signal. This paper describes a method for utilizing the idle time between the transmitted pulse and its reception at the receiving array. The system operation is based on linear arrays of 32 elements for both transmit and receive. Short bursts of ultrasonic energy, several cycles in duration, are focused sequentially on each resolution cell of the scanned volume. The focusing on transmit is achieved by suitably delaying the energizing pulses to the individual transducers. Focusing on receive is achieved by limiting the reception period for each transducer to the time during which a received echo is expected from the resolution cell at the focal point. This allows several pulses to be transmitted before reception of the first echo, which considerably increases the scan rate. This paper presents the initial results of a prototype system and compares them with a computer simulation, enabling an evaluation of the system and its potential to be made.
Stability of vowel formants based on a simple acoustic tube model and a tongue model
Authors: Kakita Yuki , Honda Kiyoshi
Published: October 2005

Mapping from articulatory parameters to acoustic parameters for vowel(s) was examined based on a simple acoustic tube model of the vocal tract and on a three-dimensional model of the tongue. In the acoustic tube model, two articulatory parameters, i.e., the location (L) and size (S) of the constriction, were selected. The second formant frequency showed an interesting folded pattern, as L varies, in the vicinity of the formant frequency for the vowel /i/. However, only using L and S, no other quantal characteristics in Stevens' sense [K. N. Stevens, Human Communication, A Unified View, edited by P. B. Denes and E. E. David, Jr. (McGraw-Hill, New York, 1972), pp. 51–66] were observed. On the other hand, the tongue model demonstrated stable formant frequencies for the vowel /i/ as reported in our previous paper [O. Fujumura and Y. Kakita, Frontiers of Speech Communication Research, edited by B. Lindblom and S. Ohman (Academic, London, 1979), pp. 17– 24]. The stabilizing effect of muscle contraction on formant frequencies is further discussed.
Use of the x-ray microbeam system for the study of articulatory dynamics
Authors: Nadler Robert D. , Abbs James H.
Published: October 2005

The new University of Wisconsin low-dosage x-ray microbeam system is capable of tracking the movements of multiple (up to ten) small (2–3 mm) gold pellets attached to speech articulators. A variety of speech and nonspeech research questions are currently being addressed by investigators using the microbeam system. These include studies of linguistic issues, acoustic and articulatory modeling, speech motor control, articulatory kinematics, mastication, and swallowing. The system also permits digitization of wideband speech acoustic and other physiological signals. These signals, obtained along with articulatory pellet tracking, include multichannel EMG, glottal impedance, differential oral and nasal airflow rate, air pressure, rib cage and abdominal movement, and external lip LED marker movements. A brief description of the x-ray system operating characteristics and performance specifications as well as overall facility data acquisition and analysis capabilities will be provided. Sample data will be presented in order to illustrate recent findings and highlight important practical considerations associated with running microbeam experimental protocols. [Support for this facility is provided by NINCDS (NS-16373).]
Vocal tract dimensions obtained from magnetic resonance images
Authors: Baer T. , Gore J. C. , Gracco L. C. , Nye P. W.
Published: October 2005

Serial magnetic resonance images (MRIs) of the vocal tract were obtained from two speakers of English during steady-state productions of nine isolated vowels including the four point vowels. Vowels were sustained for about 2.5 min, interrupted only by inhalations. Maintenance of a stable configuration was aided by a head positioner and by constantly hearing the target vowel. Images were obtained in the transaxial, and also in the sagittal and coronal planes for the four point vowels. Images representing 0.5- to 0.8-cm slice thickness were obtained at 0.5-cm intervals. Computer-assisted tracings of the boundaries of the vocal tract were used to construct a three-dimensional digital model of the airway. Using methods from the Haskins articulatory synthesizer, vocal-tract area functions were derived and vowels were resynthesized. Analysis of the first three formants showed good agreement with the subjects' original productions. Data on the relationship between the sagittal dimensions and the cross-sectional areas at various positions in the vocal tract were also obtained and will be reported. [Work supported by NIH, the Klingstein Fund, General Electric Co., and the Yale School of Medicine.]
Viscous flow analyses of glottal models using a finite element method
Authors: Iijima Hirohisa , Miki Nobuhiro , Nagai Nobuo
Published: October 2005

Some numerical flow analyses for glottal models using a finite element method are shown. The basic equations to be analyzed are two-dimensional Navier-Stokes equations, where the airflow from the lung is assumed to be an incompressible viscous fluid. Both the steady-flow and the unsteady-flow analyses are performed. In the case of the steady-flow analysis, a Newton-Raphson iteration is used to obtain the solution. The generation and the growth of vortices and the complication pressure distributions were found to be affected by the viscosity. In the case of the unsteady flow, the velocity correction method is used to form the discrete finite-element equations. As a result, a dynamical downstream movement of the vortices was determined. Both in slow steady flow and fast unsteady flow vortices were generated in the glottis. These results indicate that the vortex at the glottis cannot be ignored for voiced sounds.
Vocal-tract areas versus articulatory parameters in speech production modeling
Authors: Schroeter J. , Larar J. N. , Parthasarathy S.
Published: October 2005

Evaluation of articulatory codebooks [e.g., J. Schroeter et al., J. Acoust. Soc. Am. Suppl. 1 82, S54 (1987)] has clearly shown that improvements can be realized by inserting codewords that reduce access error for certain problematic sounds (e.g., /r/, /l/). Originally, it was not clear whether the needed shapes are attainable with the articulatory model used to convert geometrical parameters of the tract model into area data. Comparing two simple articulatory models did not reveal major differences between them. Both seem to be able to cover the formant space adequately when driven by random parameter values that included formant configurations similar to those of /r/ and /l/. Different optimization algorithms, however, were only moderately successful in finding the global optimum in these cases. The approach taken to overcome this problem was to optimize vocal tract areas directly, thus eliminating any articulatory model. Instead of the geometric constraints inherent in an articulatory model, only loose constraints of specified bounds were imposed on each of the tract sections. These bounds were obtained from histograms of section areas computed from the largest articulatory codebook. In the analysis/synthesis system, area optimization showed superior performance over articulatory model parameter optimization.
Three-dimensional representation of articulatory kinematics from x-ray microbeam data
Authors: Westbury John R. , Xue Qiuzhen
Published: October 2005

Records of speech-related movements of flesh points and anatomic landmarks obtained from the University of Wisconsin x-ray microbeam system are fundamentally two dimensional in the sense that they provide time histories of relative positions of points within a plane. However, the third spatial dimension associated with each point is implicit in its two-space representation and, under special conditions, can be reconstructed mathematically. For example, three points attached to a rigid body such as the mandible determine a system of three polynomial equations, which, when solved, provides an account of the location of each point with respect to sagittal and coronal plane axes. Both the feasibility and resolution limits of a conventional numerical approach to this problem have been established by analysis of calibrated movements of three-point arrays attached to a machine-driven phantom and tracked by the microbeam system. Moreover, the same analysis procedure has been applied to kinematic data for multipoint arrays attached to the head and mandible of nine adult subjects to determine whether and to what extent their respective movements, during speech and other selected oral motor behaviors, are restricted to the sagittal plane. The advantages of a three-dimensional representation of speech motor behavior for at least these structures, within the context of recent microbeam experiments, will be discussed. [Work supported by NIH Grant NS-16373.]
Analysis of tongue motion for the dental consonants based on the high-speed palatographic data
Authors: Mizutani Takao , Hashimoto Kiyoshi , Wakumoto Masahiko , Hamada Hareo , Miura Tanetoshi
Published: October 2005

Using a new high-speed palatograph system, tongue motions for dental consonants were recorded at a rate of 250 frames per second, and contact patterns of different consonants were compared using the gross features of the contact area (front-back position and high-low position). Each of five male subjects uttered 30 nonsense English syllables. /hə'CV/ (C = /t,d,n,s,z,r/, V = /a,i,u,e,o/). Then the front-back position of the contact area is represented by the position of the center of gravity of the contact area. Information on the vertical position of the tongue was expressed by the total number of contact points between the tongue and the palate. Representation of the contact pattern in the two-dimensional space of these parameters shows the characteristic feature for each utterance. A distinctive feature among the plosives /t,d,n/ is that the tongue position is more frontal and/or higher for /t/ than for the other two plosives /d,n/. As for the fricatives /s/ and /z/, the tongue position for the latter is usually more frontal than for the former. [Work supported by MESC of Japan.]
Some factors affecting vowel articulation
Authors: Faber Alice , Raphael Lawrence J.
Published: October 2005

As part of an extensive series of studies of tongue activity in vowel production and of the muscle activation patterns producing this activity, data were gathered from one speaker (LJR). Four sets of 15 repetitions of 15 English vowels and diphthongs in a /pVp/ context were produced, in four separate conditions (± bite-block, rested versus fatigued). Acoustic analysis of each token was undertaken, along with analysis of the electromyographic signals, recorded, in parallel, from seven intrinsic tongue muscles and the lower obicularis oris. The vowels in the bite-block conditions differed from the corresponding non-bite-block vowels in F1/F2 values and in the consistently stronger EMG signals recorded for the former. In addition, tokens from the “fatigued” conditions were shorter than those from the “rested” conditions and, for some vowels were characterized by a markedly higher F0. [Work supported by NIH.]
Stable lingual gestures in vowel articulation
Authors: Alfonso P. J. , Horiguchi S.
Published: October 2005

Lingual movements monitored by lateral cineradiographic pellet tracking along with first and second formant frequencies for the articulation of /i/ and /u/ in labial, alveolar, and velar stop (əCVC/ syllables were analyzed in order to quantify both the relatively stable and more variable components of vowel-related tongue movements that occur as a function of stop coproduction. Horizontal and vertical tongue displacements varied by as much as 10 mm at tongue body locations for /i/ and 6 mm at tongue blade and anterior tongue body locations for /u/. Formant frequencies varied correspondingly. However, vertical displacement of the tongue blade for /i/ and of the posterior tongue body for /u/ were much more stable. These relatively stable displacement components suggest that the characteristic gestures for /i/ and /u/ act to create critical oral cavity apertures by tongue blade and posterior tongue body vertical displacements, respectively. The precise anterior-posterior locations of the lingual constriction are not specified in the gestures and are free to vary with consonantal coproduction. [Work supported by NIH NS-13617 and NS-13870.]
The effect of wearing aerodynamic measuring devices on speech articulation
Authors: Mahshie James J.
Published: October 2005

Aerodynamic measures of speech production have been used to obtain insights into the dynamic properties of the vocal tract during speech production. It is unclear, however, how wearing devices such as the pneumotachograph and oral pressure transducers affects the articulatory processes being studied. The present research examined the articulatory characteristic of speech production by two normal speakers under two conditions: (1) while wearing a Rothenberg type pneumotachograph mask and oral pressure transducer and (2) without these devices. The x-ray microbeam data were obtained for lip, jaw, and tongue movement during multiple productions of voiced and unvoiced plosives in varied vowel contexts. Preliminary analysis suggests that articulatory dynamics appear not to change as a result of wearing the mask, although movement amplitudes may. Comparisons between the two conditions will be presented, together with implications for use of such measures as indices of speech articulatory behavior.
Evaluation of the sound field in a room using PICC
Authors: Yamaguchi Kiminori , Ono Takahiko , Mizota Hirokazu , Yahata Yasuhiko
Published: October 2005

To find an adequate physical parameter that can explain the subjective impression of the sound field properties of a room, the PICC (perceptual interaural cross-correlation coefficient) is discussed. The PICC is a special interaural cross-correlation coefficient taking into account Haas' effect on hearing characteristics. Two experiments are reported in this paper. The first experiment was done in an actual auditorium with a volume of 9000 m3. The speech signal sources were recorded at several seats in this auditorium; then a listening test on the subjective evaluation of the spatial impression was performed using these signals. At the same time, the PICC was measured by the synchronous response-multiplication method at each seat. The experimental results show agreement between the psychological scale of the spatial impression and the value of the PICC. The second experiment examined whether the PICC is useful in explaining the size of the sound image of reproduced sound sources in a small room. Here, a listening room with a volume of 50 m3 was used. Several sound sources were prepared using comb filters. The results of the listening test on the size of the sound image were correlated with the value of measured PICC for each of the sound sources.
Efficient subband coding of speech with optimized uniform DFT filter banks
Authors: Satt A. , Malah D.
Published: October 2005

Uniform DFT filter banks (FB) offer reduced implementation complexity of subband coders (SBC) as compared with QMF-based SBC. However, because known design techniques aim at minimizing the overall response error of the FB, using either deterministic [V. K. Jain and R. E. Crochiere, Proc. ICASSP 83, 228–231 (1983)] or statistical [A. Dembo and D. Malah, IEEE Trans. Acoust. Speech Signal Process. ASSP-36, 328–341 (1988)] error measures, the performance of DFT-based SBC was found to be subjectively inferior. A new approach is presented for DFT-FB design, which is based on a frequency-doman distortion function in which different weights are applied to the different error components (including interband aliasing and leakage of both signal and quantization noise) thus allowing an optimized design for SBC. The minimization of the proposed distortion function results in two sets of linear equations that are solved iteratively to obtain the optimal analysis and synthesis prototype filters. A 16-band DFT-based SBC operating at 16 kb/s with the designed filters was found in simulations to have subjective and objective performance similar to a QMF-based SBC at the same rate, but with less than half of the computations.