bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth and dissolution of a contrast microbubble: Effects of encapsulation
Authors: Sarkar Kausik , Jain Pankaj
Published: September 2008

Micron-size gas bubbles are intravenously injected into patients body at the time of ultrasound imaging to improve image contrast. The bubbles are encapsulated by a thin layer (4–10nm) of protein, lipids and other surface active materials, to prevent their premature dissolution in the blood. A model will be presented that describes the dissolution of a microbubble accounting for the effects of encapsulation. The encapsulation hinders the permeability of the gas-liquid surface and its elasticity balances the surface tension induced stress. Both these effects will be explicitly modeled. The model behavior will be discussed for variations of the material parameters and conditions (encapsulation permeability and elasticity, mole fraction of the osmotic agent and liquid saturation). The encapsulation significantly affects the bubble growth and dissolution including their time scales.
Echogenic liposomes loaded with recombinant tissue-type plasminogen activator (rt-PA) for image-guided, ultrasound-triggered drug release
Authors: Smith Denise A. B. , Vaidya Sampada , Kopechek Jonathan A. , Hitchcock Kathryn E. , Huang Shaoling L. , McPherson David D. , Holland Christy K.
Published: September 2008

A recently developed ultrasound contrast agent, rt-PA-loaded echogenic liposomes (TELIP), was assessed in vitro using a clinical diagnostic ultrasound scanner (Philips HDI 5000) equipped with a linear array (L12-5). The stability and echogenicity of static TELIP suspensions were determined using 4.5-MHz harmonic B-mode pulses (Pr=120 kPa; MI=0.04) in an anechoic chamber. An in vitro flow phantom with a flow rate of 5 ml/min at 37°C was also used to assess TELIP for ultrasonically-triggered drug release. TELIP samples were exposed to: (1) Fundamental 6.9-MHz B-mode pulses (Pr=600 kPa; MI=0.04) where diffusion of gas out of the liposomes occurs over 60 min, or (2) 6.0-MHz color Doppler pulses (PD=3.33μs, PRF=1 kHz) at two exposure levels, 0.8 MPa (MI=0.22) for which acoustically driven diffusion was evident or 2.6 MPa (MI=0.7), for which rapid fragmentation was confirmed. Exposure of TELIP to Triton-X, a nonionic detergent, served as a positive control for drug release. Release of rt-PA for each ultrasound exposure protocol was assayed spectrophotometrically (Shimadzu UV-1700). The thrombolytic drug remained associated with the lipid bilayer when exposed to B-mode pulses over time and was released when exposed to color Doppler pulses. [This work was supported by NIH 1RO1 NS047603 and NIH 1R01 HL074002.]
Acoustic targeted drug delivery in neurological tissue
Authors: Lewis George , Olbricht William , Lewis George
Published: September 2008

The success of treating brain cancer such as neuroblastomas and neurofibromatosis has not been very effective, and is in fact the leading cause of cancer-related death in patients younger than age 35. In the last 10 years recent developments in drug delivery methods have allowed doctors to implant/inject time-release drugs into the tumor cavity that allows for continuous release of chemotherapy; however results from these studies have not been as successful as anticipated. It is believed that the non-treated cancerous cells are able to migrate from the original tumor site, and relocate beyond the diffusion range for effective drug treatment. In this study we utilize high frequency focused ultrasound to increase drug perfusion into phantoms that mimic brain tissue as a method to increase the rate of drug permeation into the tissue before vascular clearance and cell migration reduce its effectiveness. Using various acoustic pulse sequences we show a substantial increase in drug perfusion into brain mimicking tissue then can be achieved by diffusion alone. We are therefore able to reduce the time of delivery, the amount of drug delivered and the drugs local impact range. This could significantly increase the success of treatment and reduce systemic effects of chemotherapy.
Robotic high intensity focused ultrasound (HIFU) control for tumor treatment
Authors: Kambhampati Shivkumar , Zderic Vesna
Published: September 2008

Introduction: Robotic surgery, with more precise and defined movements compared to manual human surgery, is the wave of the future. The purpose of this project is to move the focus of the HIFU transducer using a 3-axis robotic work cell in order to treat the whole volume of a tumor in a precise manner. Methods: A 3-axis robotic work cell from Arricks Robotics was chosen based on price ($3300 USD), precision, range of movement, and payload capacity (up to 2Kg). A LabVIEW program serves as the entire surgery interface including movement options, treatment algorithms with up to 25 points within the tumor, and a guidance system via ultrasound imaging and the hyperechoic spot of the HIFU focus. Results: The robotic work cell could achieve 0.5mm per 10mm precision and speeds of 10mm/sec in real-time within a cell of 180mm by 180mm by 50mm with a HIFU transducer mounted. Testing with native MD-2xp software has resulted in distance testing with less than 2% error in all three axes (0.7% in X, 1.5% in Y, 1.3% in Z). Conclusion: The final outcome will provide a robust, computer-assisted, cost-effective way to perform robotic HIFU surgery.
Comparison of pathway in high-intensity focused ultrasound lesion production
Authors: Zhou Yufeng , Hwang Joo Ha , Kim Kwang , Hwang Joo Ha
Published: September 2008

High intensity focused ultrasound (HIFU) is being evaluated for noninvasive treatment of solid tumors. The temperature at the HIFU focus can reach over 65°C, denaturing cellular proteins and resulting in coagulative necrosis and lesion formation. One common method for delivering HIFU therapy clinically is using the spot accumulation method that delivers sequential individual treatment spots. Because of thermal diffusion from nearby treatment spots, the size of subsequent lesions will gradually become larger as the HIFU therapy progresses, which may cause insufficient treatment of the initial spots, and over-treatment of later spots unless parameters are changed during treatment. A new pathway for HIFU treatment is proposed and compared with the conventional sequential path. Modeling, in vitro phantom and ex vivo bovine liver experiments demonstrate that the new treatment path produces more uniform lesions than the conventional treatment path (p<0.05). The relationship between lesion area/volume and delivered ultrasound energy and the dose-dependent discrepancies between scanning paths were also studied. In addition, the temperature changes in the ex vivo system were measured using a thermocouple array. Altogether, the new treatment path appears to be advantageous for producing more uniform lesions without modifying HIFU parameters during treatment or significantly increasing the scanning time.
Optimization of lesion formation using high-intensity focused ultrasound at large tissue depths
Authors: Samuels Joshua , Zderic Vesna
Published: September 2008

Background: The objective was to determine the parameters to making a sizable, controlled lesion deep within the treated tissue using high-intensity focused ultrasound (HIFU). High HIFU intensities allow for rapid temperature rises in tissue used for tumor ablation. Methods: Various experiments were conducted manipulating amplitude and treatment time to produce lesions at full focal length (5.2 cm) of a 3.35 MHz HIFU transducer. Beef thigh was used, as it closely resembles the nonuniformity of human tissue unlike phantom-gels or turkey breasts. Results/Discussion: Inconsistent lesion formation in our experiments showed that deep lesions in a nonuniform medium are not easily created. At 5.2 cm, in situ HIFU intensities dropped to 170–260 W/cm2 (vs. 40,000–60,000 W/cm2 free field). Reflections off fat, fascia, and bubbles formed at the HIFU focus (at higher intensities) often appear to result in prefocal lesion formation (average total depth of 3.8 cm). Lower intensities over longer treatment times (up to 120 s) yielded desirable lesion depth (average depth of 4.5 cm, highest depth of 6.8 cm), showing longer treatments at lower intensity could be the key to precise deep lesions. Lesion volumes ranged from 0.1 to 26.5 cc. Conclusion: The challenges posed by treatment of nonuniform tissues are similar to those to be encountered in clinical applications.
Enhanced high-intensity focused ultrasound lesion formation in tissue phantoms using embedded fibers
Authors: Labuda Cecille , Church Charles C.
Published: September 2008

High intensity focused ultrasound (HIFU) is currently being developed for hemorrhage control, since it provides rapid energy deposition in the focal region of the field. Near large vessels, the deposition rate is limited by loss of heat to the blood flow, making hemorrhage control difficult. In this study, nylon, copper, and stainless steel fibers were embedded in an albumen-containing tissue phantom to investigate whether these fibers would enhance the HIFU heating effect. The embedded fibers were sonicated at high power, and control sonications were performed away from the fibers. Visible regions of protein denaturation, or lesions, were produced. Control lesions were ellipsoidal and elongated along the acoustic axis. Lesions at the stainless steel and copper fibers were similar in shape, but smaller than the control lesions. Lesions produced at the nylon fibers were teardrop-shaped, elongated along the fiber, and larger than the controls. The roles of thermal conductivity and ultrasonic absorption in the enhanced heating effect were considered. It was concluded that a material of low thermal conductivity and high ultrasonic absorption, such as a polymer fiber, was most suitable for enhancing the HIFU heating effect. [Work supported by DAMD17-02-2-0014.]
Cost-effective radiation force balance for calibration of therapeutic ultrasound devices
Authors: Razjouyan Faezeh , Zderic Vesna
Published: September 2008

The objective was to create an inexpensive, portable, and accurate absorptive radiation force balance to measure acoustic powers of up to 100 watts generated by the high intensity focused ultrasound (HIFU) transducer. This paper describes the process of making an effective absorbing target with commercially available ingredients. Four different absorbing targets consisting of nickel powder, silicone elastomer, and microballoons were prepared and tested. Silicone Sylgard (Dow Corning, MI) was used for all samples. However, two different microballoons (acrylic and phenolic) and two different nickel powders (high density and spherical nickel powder) were used. The final results were compared with a commercially available reflection radiation force balance (RRFB). The results for the same 3.5 MHz HIFU transducer (Sonic Concepts, WA) revealed that a combination of spherical nickel powder (Alfa Aesar, MA) with acrylic microballoons (Douglas Sturgess, CA) offered an average efficiency of 89.8%, compared to that of RRFB, which was 80.7%. A combination of high density nickel powder (Inco Inc., Canada) with acrylic and phenolic microballoons were 82.5% and 84.2%, respectively (for the same HIFU transducer), while spherical nickel powder and phenolic microballoons (US Composites, FL) had efficiency of 64.4%, indicating incorrect measurements of HIFU transducer efficiency.
Detection of brachytherapy seeds at varying angles with a singular-spectrum-analysis algorithm
Authors: Ramachandran Sarayu , Mamou Jonathan , Feleppa Ernest J.
Published: September 2008

A singular-spectrum-analysis (SSA) algorithm previously was shown to be successful in detecting brachytherapy seeds in B-mode images when seeds were orthogonal to the ultrasound beam. In this study, the algorithm was extended to detect seeds at angles to the beam. The SSA algorithm derives P-values from selected eigenvalue pairs of the autocorrelation matrix of seed echo signals. The P-value indicates the probability of presence of a seed. A seed inserted in a gel pad and another inserted in beef tissue were scanned with a 5-MHz transducer. The seed angle was varied from orthogonal to the beam to 23 deg from orthogonal, using 1-degree increments. Simulations of seed echoes based on empirical data were generated and used to test the algorithm. Success in seed detection was expressed by a score computed from P-values. Scores for simulations decreased from 0.8 to 0.45 as the angle increased from 0 to 12 deg. Scores for experimental data varied from 0.74 at 0 deg to 0.62 at 23 deg; the lowest value was 0.1 at 7 deg. Accordingly, the SSA algorithm was successful in detecting the seed with clinically relevant angles between seed and beam.
An investigation of the capabilities of a short hydrophone array towed by an ocean glider
Authors: Dossot Georges A. , Miller James H. , Potty Gopu R. , Sullivan Edmund J. , Holmes Jason D. , Lynch James F. , Glenn Scott
Published: September 2008

During the Shallow Water Experiment (SW06) a Webb Slocum glider, deployed by Rutgers University, demonstrated that gliders are promising vehicles for towing short acoustic arrays. The gliders saw-tooth trajectory allows for sampling the water column at varying depths and ranges. Further, the glider provides a low-speed platform, allowing for a flow-noise free towed array, which is ideal for the processing of low level signals. One attractive application for glider-towed arrays is target tracking. By using the passive synthetic aperture effect, coupled with a near-field model for the signal, the coordinates of an acoustic source can be estimated using a Kalman filter, but without the necessity of the maneuver normally required by bearings-only tracking. This is possible since the large aperture traced out by the glider permits wavefront curvature to be exploited for range estimation. Using synthetic narrowband data, it is shown that the range and bearing of a low-level acoustic source can be estimated without changing the gliders course. The algorithm is based on an Unscented Kalman Filter. Also, an approach for the broadband problem is outlined. [Work sponsored by the Office of Naval Research.]
Impact of structural support on vector sensor acoustic performance
Authors: Deveau David
Published: September 2008

Vector sensors hold great promise for the exploitation of undersea acoustics by providing the ability to measure the acoustic intensity. Current sensor developments can measure the acoustic acceleration in three dimensions as well as the pressure, which when combined through a cross-correlation produces the acoustic intensity field surrounding the sensor. Mathematical studies indicate that a gain of 4.6 dB is achievable by beamforming the sensor’s three cardioid outputs with the pressure sensor’s omnidirectional response. In these studies, the mechanics of physically retaining the sensor in position is not considered, but is necessary to allow the sensor to freely sense particle velocity/acceleration and not shadow the sensor to the surrounding pressure field. A set of PVC frames was constructed to hold an individual sensor, which was then combined to form an array of sensors for use in a long-term shallow water acoustic field intensity study. These frames are modeled to determine the level of forward and backscatter caused by the flooded PVC pipes and the possible impact to the theoretical patterns. The physical structures are then calibrated in a controlled measurement facility to determine if the accelerometers move freely in all three dimensions to generate the cardioid patterns necessary to achieve the gains predicted by intensity models over similar pressure sensor configurations.
Enhancing underwater acoustic vector sensor measurement performance by point source analysis
Authors: Clark Joseph A.
Published: September 2008

The beam pattern response to an actual point-like source that is measured with a vector sensor has been found to differ noticeably from the computed response to an idealized point source even under very low ambient noise conditions. This difference can be exploited to enhance underwater acoustic vector sensor measurements by a repeated process of subtracting an equivalent point source response from the measured response and analyzing the remainder beam. Details of a method for carrying out this type of analysis will be presented. The method will be illustrated with data from an at-sea experiment conducted at a U. S. Navy radiated noise facility near Ketchikan, Alaska (SEAFAC). Features of the equivalent point sources determined by the method will be shown to correspond to known characteristics of the ambient noise field at the measurement site. An evaluation of the improvement in detection and localization performance which can be achieved by the point source analysis method will be reported.
Development of a flextensional transducer for high resolution seismic imaging
Authors: Dubus Bertrand , Haw Gerard , Granger Christian , Mosbah Pascal , Kosecki Arkadiusz , Piwakowski Bogdan , Meynier Patrick
Published: September 2008

Piezoelectric transducers are considered as potential sources for geophysical applications such as 4D monitoring or shallow subsurface survey, which require high repeatability and precise control of the emitted signal. However, the use of piezoelectric sources is limited by their low power and narrow bandwidth. Flextensional transducers are compact, high power, low frequency, wide-band projectors used in underwater acoustics. The design, fabrication and test of a flextensional transducer for high resolution seismic imaging are presented in this paper. Circuit modeling is used to discuss the general properties of piezoelectric sources radiating in the ground. Finite element simulations (ATILA code) are conducted to design a wide band 500–1500 Hz flextensional transducer. On-site tests are performed for a typical configuration of shallow subsurface survey. The prototype transducer is compared to a weight drop which constitutes a well-known seismic source. By taking advantage of the source repeatability and using specific signal processing, it is found that the flextensional transducer is equivalent to weight drop ranging from 300 to 1300 J. Bandwidth is increased by 200 to 300%, leading to a significant improvement of image resolution.
Soundscapes without decibels
Authors: Blomberg Leslie D.
Published: September 2008

This paper will examine the advantages and limitations of describing soundscapes in terms of the effects of on specific populations.
Identification of distinctive patterns and features in soundscapes
Authors: Genuit Klaus , Fiebig Andre
Published: September 2008

The environmental noise of several cities located all over the world was recorded, compared, and analyzed. The analyses were focused on the determination of distinctive features and significant patterns of the respective soundscapes, which led to the unique sound of the urban places and that are important because of their individuality, numerousness, or domination. By means of this study and the applied analyses, several acoustical properties, particularities, and patterns were identified, which could be the starting point for an acoustical-orientated soundscape classification. It was found that the environmental noise differs, for example, in character, spectral content, time structure, degree of variation of certain parameters, background to foreground relationship caused by the location-specific noise sources, and their spatial as well as temporal occurrence. It is important to emphasize that the acoustical analyses, on the one hand, have to capture the global, overall impression of the soundscape and, on the other hand, must recognize and adequately interpret single noise events, which also cause strong reactions and emotions. The presentation will show and discuss the case study results.
Shape factor characterization of fibrous media with a temperature gradient
Authors: Slaton William V.
Published: September 2008

Recent theoretical work generalizes thermoacoustic theory to random porous media [H. S. Roh et. al., J. Acoust. Soc. Am. 121(3), 1413–1422 (2007)]. Characteristics of the porous media, such as the tortuosity and dynamic shape factors for viscous and thermal effects, are introduced into the thermoacoustic wave equation and may be determined by suitable impedance measurements at zero temperature gradient. This theoretical approach may also be used to model fibrous media, such as fiberglass or steel wool. A new technique to determine the scaling factors for fibrous media utilizing a single-step finite difference inversion of the thermoacoustic wave equation [R. Raspet et. al., J. Acoust. Soc. Am. 103(5), 2395–2402 (1998)] with zero temperature gradient will be presented. Roh et. al. predict that acoustic gain with a nonzero temperature gradient may be written in terms of these scaled cylindrical dissipation functions. The acoustic gain term may also be determined by suitable application of the single-step finite difference technique. [This material is based upon work supported by the U. S. Army Space and Missile Defense Command under Contract No. W9113M-06-C-0029.]
Design environment for low-amplitude thermoacoustic energy conversion (DeltaEC)
Authors: Clark John P. , Ward William C. , Swift Gregory W.
Published: September 2008

The Los Alamos thermoacoustics code, available at www.lanl.gov/thermoacoustics/, has undergone extensive revision this year. New calculation features have been added to the original Fortran computational core, and a Python-based graphical user interface wrapped around that core provides improved usability. A plotter routinely displays thermoacoustic wave properties as a function of x or tracks results when a user-specified input variable, such as frequency or amplitude, is varied. The Windows-like user interface provides mouse-based control, scrolling, and simultaneous displays of plots and of several categories of numerical values, in which color indicates important features. Thermoacoustic phenomena can be calculated with superimposed steady flow, and time-averaged pressure gradients are calculated. In thermoacoustic systems with toroidal topology, this allows modeling of steady flow caused by gas diodes (with or without time-averaged heat transfer) and Gedeon streaming. Thermoacoustic mixture separation is included, also with superimposed steady flow. The volume integral of the complex gas momentum is available, so vibrations of thermoacoustic systems can be analyzed.
Thermoacoustic quality factor measurement in a Helmholtz resonator
Authors: Smith Holly , Slaton William
Published: September 2008

A Helmholtz resonator consists of a hollow neck attached to an empty chamber. This resonator can be modeled as a spring-mass system in which the air moving inside the neck acts as the mass and the gas inside the chamber acts as the spring. Every Helmholtz resonator has a characteristic quality factor that is dependent upon the total mechanical resistance present. A system with low resistance will have a narrow peak on its amplitude versus frequency graph and a high quality factor, whereas a system with high resistance will have a broader peak and a low quality factor. In this experiment, a porous ceramic substrate is inserted into the neck of a Helmholtz resonator. Introducing this substrate into the neck of the Helmholtz resonator alters the resonance frequency and the quality factor of the resonator. The quality factor will be shown to be increased with increased temperature difference until spontaneous onset of sound generation. The effect of convection will be studied by exploring the dependence of the quality factor on the physical orientation of the resonator with respect to the vertical. [This work was supported by the Arkansas Space Grant Consortium and the University of Central Arkansas University Research Council.]
Thermoacoustics and thermal dissociation of water
Authors: Swift Gregory W. , Geller Drew A.
Published: September 2008

Near 2600 K, 10% of water molecules are thermally dissociated at atmospheric pressure, with a reaction time constant below 1 ms. Such temperatures can be reached with focused sunlight. To use this endothermic reaction for the production of hydrogen, the hydrogen must be separated from the oxygen at high temperature, because they would quickly recombine to form water again, if the unseparated mixture were simply returned to lower temperatures. We have considered thermoacoustic mixture separation for this purpose. Our calculations show that the thermal-diffusion ratios are high enough to yield steadily flowing streams of hydrogen-enriched steam and oxygen-enriched steam in a separation channel less than a wavelength long. However, the thermoacoustic power density in 1-bar steam is low, so the required apparatus would be large, needing alot of expensive and fragile high-temperature material, such as calcia-stabilized zirconia. Our estimates show that this approach to solar hydrogen production would be approximately 30 times more expensive than solar-Stirling electricity generation driving traditional water electrolysis. [Work supported by DOE Office of Science.]
The acoustic vowel space in speech disorders: Data and interpretation
Authors: Weismer Gary
Published: September 2008

The acoustic vowel space, usually defined by the area enclosed by the corner vowels in an F1-F2 plot, may have some use as a general index of speech severity in various types of speech disorders. In this presentation, vowel space data will be reviewed for a number of different speech disorders, and the issue of the role of vowel space measurements in understanding both the underlying speech production deficit, as well as deficits in speech intelligibility, will be considered. Vowel space estimates, it will be argued, are in large part a gross estimate of speech motor control deficit. This is in contrast to a view of vowel space estimates as direct predictors of, say, specific aspects of segmental articulation difficulties or componential aspects of speech intelligibility deficits (for example, the extent to which vowel problems predict a speech intelligibility deficit). Some suggestions for future work, including extensions of the vowel space concept to include planar estimates of formant motion, will be presented. [Work supported by NIH.]
Clear speech effect on vowel production across languages
Authors: Smiljanic Rajka , Bradlow Ann
Published: September 2008

In this talk, we discuss vowel production in clear speech, a distinct mode of speech production intended to enhance intelligibility, across languages with different phonological properties (Croatian and Spanish with small vowel inventories vs. English with a large vowel inventory). A comparison of Croatian and English revealed the equivalent clear speech vowel space expansion in both languages. In addition, listeners recognized words in noise more accurately in clear than in plain speech in their native language, establishing that the plain-to-clear speech articulatory modifications increased intelligibility. A comparison of Spanish and English also showed similar amounts of vowel space expansion as well as the maintenance of coarticulatory patterns in clear speech for both languages. The inventory-independent vowel space expansion in all three languages suggests that talkers hyperarticulate even when segments are unlikely to be perceptually confusable (few vowel categories that are fairly distinct). The maintenance of coarticulation further suggests that spreading of segment identity across neighboring sounds may be beneficial to the listener. In this talk, we also discuss various measures of vowel space expansion and different clear speech strategies across talkers. We conclude with some remarks about the link between the identified acoustic-phonetic features of clear speech and intelligibility.
Listener influences on vowel intelligibility
Authors: Bent Tessa , Hargus Ferguson Sarah , Kewley-Port Diane
Published: September 2008

Do the acoustic-phonetic parameters that promote highly intelligible speech vary across different listener populations? The current study investigated whether inter-talker differences in American English (AE) vowel intelligibility were maintained across three listener groups: Normal hearing native AE-speaking adults (NH), normal hearing Korean-speaking adults learning AE as a second language (L2), and hearing impaired native AE-speaking adults (HI). These groups heard recordings of 10 AE vowels in /bVd/ context produced in conversational speech style by 12 talkers. The stimuli were mixed with noise and presented for identification in a 10-alternative forced choice task. Vowel intelligibility varied substantially among the talkers. There were significant correlations of talker scores for the NH and HI listeners, but not for NH and L2 listeners. An analysis of acoustic-phonetic vowel features indicated that vowel intelligibility was negatively correlated with vowel space expansion for the HI group, while for the L2 group, intelligibility was positively correlated with vowel duration. These data suggest that although both HI and L2 listeners have difficulty in noisy listening situations, their degraded performance has different underlying causes that lead to substantial differences in the perception of the intelligibility of different talkers. [Work supported by NIH-NIHDCD 02229 and T32-DC00012.]
Nonnative phonemes are open to native interpretation: A perceptual learning study
Authors: Sjerps Matthias J. , McQueen James M.
Published: September 2008

Four experiments examined whether Dutch listeners can learn to interpret a nonnative phoneme (English [θ]) as an instance of a native category (Dutch [f] or [s]). During exposure in Experiment 1, two listener groups made lexical decisions to words and nonwords. Listeners heard [θ] replacing [f] in 20 [f]-final words (Group 1), or [s] in 20 [s]-final words (Group 2). At test, participants heard e.g., [doθ], based on the minimal pair doof/doos (deaf/box), and made visual lexical decisions to e.g., doof or doos. Group 1 were faster on doof decisions after [doθ] than after an unrelated prime; Group 2 were faster on doos decisions. The groups had thus learned that [θ] was, respectively, [f] or [s]. This learning was thorough: effects were just as large when the exposure sound was an ambiguous [fs]-mixture (Experiment 2) and when the test primes contained unambiguous [f] or [s] (Experiment 3). In Experiment 4, signal-correlated noise was used as the exposure sound. Listeners learned that the noise was an [f], irrespective of [f]- or [s]-biased exposure, showing that learning is determined by the new sounds spectral characteristics. Perceptual learning in a native language is thorough, and can override years of second-language phonetic learning.
Neutralization in the perception and production of English coda obstruents by Korean learners of English
Authors: Park Hanyong , Hao Yen-chen , de Jong Kenneth J.
Published: September 2008

Phonological neutralization rules require the suspension of differences between segments in perception and production. This paper examines the role of neutralization in the production and perception of Korean learners of English. In Korean, laryngeal and manner contrasts found in initial obstruents are systematically neutralized in coda position into stops that sound like voiceless stops in English. The current paper pursues two questions: (1) Does neutralization have the same effect on perceptual and production abilities? (2) are neutralization effects found with all English segments, or are they restricted to stops, which are transferred from Korean? /p, b, t, d, f, v, θ, δ/ were placed after /a/. Two tasks are compared: (A) Identification. Forty Korean learners identified coda consonants produced by four native speakers of English, using English labels. (B) Reading. Ten native English listeners identified coda consonants produced by four Korean learners. Identification errors were largely unidirectional; for example, many segments were labeled /f/, while /f/ identification was highly accurate. Reading errors were largely bidirectional with a systematic tendency for more errors, resulting in voiceless consonants and stops, conforming to the Korean neutralization pattern. Such neutralization effects were as prevalent in fricatives as stops. [Work supported by NSF.]
Experimental paradigm influence subject’s perception of attitudes
Authors: Menezes Caroline , Erickson Donna , Maekawa Kikuo , Kawahara Hideki
Published: September 2008

Japanese utterances spoken with different attitudes (admiration, suspicion, and disappointment) were independently manipulated for pitch-contour and voice quality using STRAIGHT {Kawahara}. Close copy stylization of the prototypical pitch contour for the three attitudes was imposed on the naturally spoken utterances, producing stimuli with all combinations of voice quality types and pitch-contour shapes. The utterances were submitted to two separate experiments, wherein subjects were asked to judge the attitude of the morphed utterances. The first, a forced choice experiment, asked subjects to choose if the utterances were admiration, suspicion, or disappointment, and the second, a free choice experiment, where subjects could freely choose the attitude they perceived. The results from the forced choice test indicated that subjects used pitch contour cues to choose speaker attitude. However, the results from the free choice paradigm indicated that subjects used both voice quality and intonation cues, and were able to perceive more affect types than the original three. Whereas the forced choice paradigm suggested that intonation was the primary cue for listeners to determine speaker attitudes, the free choice paradigm suggested an independence of voice quality and intonation in determining speaker attitudes, which resulted in a larger number of perceived attitudes by listeners.
On voicing activity under the control of emotion and loudness
Authors: Kim Samuel , Lee Sungbok , Narayanan Shrikanth
Published: September 2008

For a parametric study of interplay between loudness control and emotional modulation in voicing activity, electroglottography (EGG) data collected from two male and two female subjects are examined. The subjects read emotionally neutral sentences in a self-controlled manner with four different emotional states (neutral, angry, sad, happy) and three levels of loudness (soft, normal, loud). The analysis focused on the timing and shape-related EGG waveform parameters of the vowel /a/ in the data as a function of emotional state and loudness level. Specifically, open quotient (OQ), speed quotient (SQ), and noise-to-harmonic ratio (NHR) of EGG waveform are investigated. Pitch, root-mean-square (RMS) energy, and duration of speech waveform are also analyzed. Despite inter-subject differences, some general tendencies of the EGG parameters can be observed. It is found that angry emotion shows the lowest OQ in a given loudness level, and happy emotion exhibits significantly higher OQ than angry emotion. SQ mainly varies along the loudness dimension, smaller SQ in louder voice. NHR is the highest in soft voice and shows no clear emotion-dependent pattern. The results suggest that OQ is the main EGG parameter that is controlled by speakers for emotion expression, in addition to its role in loudness control.
The effects of linguistic experience on the perception of pathologically-disordered phonation
Authors: Esposito Christina
Published: September 2008

Ladefoged [Vocal Fold Physiology: Contemporary Research and Clinical Issues, College Hill Press, San Diego, 1983] wrote, what is a pathological voice quality in one language may be phonologically contrastive in another If one persons pathology is another persons phonemic phonation, then speakers of languages with phonation contrasts should treat pathologically-disordered and linguistically-relevant phonations in the same way. To test this, Gujarati (breathy versus modal contrast), Spanish (no breathiness) and English (allophonic breathiness) listeners participated in similarity-rating tasks. One used Mazatec (breathy, modal, and creaky phonation) stimuli, the other pathologically-disordered stimuli. Gujaratis treated pathologically-disordered stimuli and Mazatec stimuli in the same way. With both types of stimuli, Gujaratis based their judgments on H1−H2 (amplitude of the first harmonic minus the second) and mapped the stimuli into clusters with similar H1−H2 values across the two experiments. In both experiments, English listeners relied on cepstral peak prominence and H1−H2, and Spanish listeners relied on H1−H2 and H1−A1 (amplitude of first formant peak). English and Spanish listeners grouped both types of stimuli into clusters with similar values for the acoustic measures. However, English and Spanish listeners differed in how they weighed the importance of the different dimensions across the experiments. To English and Spanish listeners, pathologically-disordered phonations are subtly different from linguistically-relevant ones.
Analysis of voice perturbations using an asymmetric model of the vocal folds
Authors: Nardone Marco , Fulcher Lewis , Scherer Ronald
Published: September 2008

A mathematical model was developed to investigate possible causes of jitter and shimmer. The model builds on the classic, lumped element model of Ishizaka and Flanagan and allows for asymmetric motions of the vocal folds and aerodynamic imbalances. The intraglottal pressures were derived from empirical pressure data obtained from a static physical model of the larynx (M5). The mathematical model is based on ten, second-order, nonlinear, coupled, ordinary differential equations that were solved simultaneously using the software Mathematica. The solutions were analyzed graphically and numerically to identify perturbations in the fundamental frequency and amplitude of the glottal airflow. Jitter and shimmer were quantified using the jitter factor and the amplitude variability index. The results indicate that only time-dependent variations in biomechanical and aerodynamic parameters result in jitter and shimmer. The magnitudes of jitter and shimmer tend to be less than those observed in the natural sounding voice, even when the asymmetries are large. Although time-independent asymmetries may cause the vocal folds to oscillate out of phase or with different amplitudes, they tend to entrain and vibrate at a common frequency. [Work supported by NIH R01DC03577.]
Phonetic correlates of phonological register in Takhian Thong Chong
Authors: DiCanio Christian
Published: September 2008

The author’s phonetic fieldwork from the Takhian Thong Chong language demonstrates that the four phonological registers are distinguished phonetically with distinct voice quality (phonation) contours, pitch contours, and durational properties. Both EGG and acoustic data were gathered from seven native speakers. A dynamic open quotient contour extracted from electroglottographic recordings demonstrates register-specific phonation type correlates. The four distinct registers are characterized by: Modal phonation throughout with a mid-level pitch, a contour from modal to tense phonation with a high rising and falling pitch contour, a contour from breathy to modal phonation with a mid-falling pitch contour, and a contour from breathy to tense phonation with a midrising and falling pitch contour. Investigations into the correlation between OQ (open quotient) values and pitch indicate a positive global correlation between the relative length of the glottal cycle and the open period, but a lack of correlation between dynamic OQ and pitch curves. Aside from providing a phonetic description of a typologically rare phonological contrast, these findings suggest that there is not a strong relationship between absolute changes in degree of glottal abduction and changes in pitch, contrary to previous claims (Silverman 1997). [Work supported by UC Berkeley Graduate Division.]
Model-based quantification of pathological voice production
Authors: Schwarz Raphael , Deliyski Dimitar , Lohscheller Joerg , Doellinger Michael
Published: September 2008

Hoarseness, the primary symptom of voice disorders, results from irregular vocal fold vibrations. The oncological therapy of laryngeal cancer may even result in a total loss of voice if an excision of the larynx, and thus, the vocal folds, is necessary. State-of-the-art voice rehabilitation technique in this case is the utilization of scarred tissue in the upper part of the esophagus for substitute voice production. The quality of laryngeal voice, as well as the substitute voice, primarily depends on the anatomy and the vibration patterns of the voice-producing element. Using endoscopic high-speed recordings, the voice generators are observed during voice production. In this work, a model-based approach feasible for the analysis and objective quantification of vocal fold vibrations, as well as the PE dynamics, is presented. By means of an automatic parameter optimization, the dynamic of a biomechanical model of the considered voice-producing element is fitted to the recorded vibration patterns. Thereby spatial and temporal properties of the vibrations are incorporated. The resulting values of the optimization parameters represent an objective quantification of the vibration patterns. In addition, the model parameters enable an approximation of physiological tissue parameters as stiffness and mass distribution.
Neural representation of pitch-shifted voice feedback at N100 and P200 components: An event-related potentials (ERP) study
Authors: Behroozmand Roozbeh , Liu Hanjun , Larson Charles R.
Published: September 2008

Numerous studies have shown that perturbations in voice pitch feedback lead to compensatory responses in voice fundamental frequency (F0), but few have reported on neural responses to the acoustical stimulation during the pitch-shifted voice feedback. In this study, randomized-onset, upward pitch-shift stimuli (60 ms duration) were presented to ten subjects during sustained vowel phonation while the event-related potentials (ERPs) were recorded through Cz-linked earlobe surface electrodes. ERPs were also recorded as subjects passively listened to the same feedback signal that was recorded during vocalization. The experimental task was repeated for 100, 200, and 500 cents conditions, respectively, and the results were compared in vocalization and listening conditions. Across three stimulus magnitudes, the N100 responses during vocalization were suppressed in comparison with those recorded in the passive-listening condition. On the other hand, the P200 responses in the passive-listening task were graded in amplitude according to the magnitude of the stimulus, with the smallest responses for 100 cents and largest for 500 cents stimuli. However, during vocalization, the P200 responses were found to be graded in the opposite way, where the largest responses were associated with 100 cents and the smallest with 500 cents stimuli.
Detecting rhythmical prominence in speech by an optimized convolution kernel
Authors: Orphanidou Christina , Kochanski Greg
Published: September 2008

We present an approach for detecting rhythmical prominence in read speech. A production experiment was conducted during which subjects repetitively read out speech to a metronome, trying to match stressed syllables to its beat. In the analysis, we compute a function from the speech waveform, related to acoustic properties of speech such as specific loudness, pitch, voicing, and spectral slope. The function is then convolved with a Mexican Hat convolution kernel. Taking large maxima in the function to be predictions of the metronome ticks, we adjust the parameters of the signal to maximize the accuracy of the predictions. The parameters are adjusted by minimizing the phase variation between metronome ticks and ticks predicted from the audio, over a specified time interval. We confirm the results by Bootstrap resampling. We find that the most important factor is the contrast in specific loudness between a syllable and its neighbors. The prominence can be deduced from the specific loudness in an (approximately) 360 ms window centered on the syllable in question relative to an (approximately) 800 ms-wide symmetric window.
The influence of position-in-utterance on the scale of articulatory gestures
Authors: Kuo Christina , Weismer Gary
Published: September 2008

The influence of prosodic structures of utterances on articulation has been of interest in speech production. Data on fundamental frequency, peak oral airflow, movement, and speech timing has been reported. Nonetheless, little is available in the literature regarding the magnitude of articulatory behavior as a prosodic phenomenon. This study is motivated by the phenomenon of articulatory declination, which is a hypothesized gestural weakening over an utterance, analogous to the better known F0 declination. An attempt is made to describe and examine articulation at the start and the end of an utterance under varied stress during sentence reading of normal speakers aged 20 to 30. Target words were ‘‘row,’’ ‘‘sew,’’ and ‘‘sigh.’’ A control word ‘‘bee’’ was included given the diphthongal nature of the three targets. Each target word was surrounded by the neutral vowel ■ and embedded in a grammatical sentence under five position-in-utterance conditions: initial, initial-stressed, final, final-stressed, and final without a following ■. Formant transitions were measured from the first glottal pulse after the consonant through the following ■. Transition extent and duration were derived for analysis. Pilot data with two participants (one male, one female) and work in progress are discussed within the framework of articulatory declination.
Gradiency and categoricity in prosodic boundary production and perception
Authors: Krivokapic Jelena , Ananthakrishnan Sankaranarayanan
Published: September 2008

A study investigating whether the production and perception of prosodic boundaries is categorical or gradient is presented. Most theories assume a small set of prosodic categories which are marked by categorically different prosodic boundaries (e.g., Beckman & Pierrehumbert 1986 Phonology Yearbook, 3, 255–309, Nespor & Vogel 1986 Prosodic Phonology), while an alternative view suggests the possibility of gradiently varying prosodic boundaries (e.g., Byrd & Saltzman, 2003 J. of Phonetics, 31, 149–180). The first part of this study is an articulatory study investigating the production of twenty-four prosodic junctures ranging from no boundary to very strong boundary. In the second part of the study listeners evaluate the perception of these same boundaries. Two evaluations (histograms and fitting mixture distributions) were conducted on both the production and on the perception data. The production of prosodic boundaries was found to be categorical, showing a large (IP) and a predominantly small prosodic boundary. The perception of prosodic boundaries showed that listeners perceive two distinct categories, but also that the data is better explained if more prosodic categories, up to 8, are assumed. [Supported by NIH.]