bluuebunny/crossref_metadata_2025 huggingface dataset:
On acoustic absorption in tissue.
Authors: Vilensky Gregory , Saffari Nader , ter Haar Gail
Published: July 2011

This work extends the relaxation theory of sound absorption to the case of continuous distribution of relaxation times. Such an extension is needed when the absorption mechanisms are not confined to viscosity and heat conduction, but are due mainly to the excitation of a large number of internal molecular degrees of freedom. In this case, the conventional Navier–Stokes equations are not sufficient, and additional equations are required to model relaxation stresses. When relaxation frequencies form a sufficiently dense distribution, as is the case for many biological fluids, it makes sense to consider the limit of continuously distributed relaxation frequencies in order to obtain the required equation for normal stresses. The proposed theory provides a means of deriving the equations of motion in physical time-space from absorption data for a wide range of absorption laws that can occur in practice. A number of experimental absorption laws are considered in detail, and the related systems of equations of motion are derived and analyzed. The methodology developed in the literature based on modeling of absorption in biological soft tissue by fractional derivatives is a special case of the proposed theory. Numerical properties of different absorption models in tissue are also presented.
In vitro validation of three-dimensional cavitation-based pressure mapping for quality assessment of clinical high intensity focused ultrasound devices.
Authors: Faragher Stuart , Collin Jamie , Hurrell Andrew , Doust Paul , Tanner Mark , Coussios Constantin-C.
Published: July 2011

Sufficiently robust and reliable quality assessment (QA) procedures are vital in assuring the widespread adoption of high intensity focused ultrasound (HIFU) for use in both thermal ablation and enhanced drug delivery. Mapping of broadband cavitation emissions in a tissue-mimicking material with a repeatable cavitation threshold offers the potential for rapid, 3-D, cavitation-based pressure mapping of the field produced by a given HIFU transducer. Previous work has demonstrated the viability of this concept, including the design and optimization of a 50-element, cylindrical array capable of mapping a collection of broadband sources distributed throughout a region comparable to the size of a typical HIFU focal volume. The work presented here relates to in vitro experimentation using the array to map cavitating fields produced by a number of HIFU transducers at a range of insonation amplitudes. Results are compared to the predicted size of the cavitation region determined via hydrophone-based characterizations of the HIFU field. Future work will involve using the array to map the instigation and evolution of cavitating fields in three-dimensions in ex vivo tissue during HIFU exposure.
An overview of acoustic research in Speech Communication.
Authors: Story Brad H.
Published: July 2011

Speech Communication in the ASA covers a wide range of research areas and brings together scientists from many different academic disciplines. This presentation will provide a brief overview of acoustic research relevant to the production, perception, and acquisition of speech, speech processing, speech intelligibility, and disordered speech.
Psychological and Physiological Acoustics: From sound to neurons to perception.
Authors: Oxenham Andrew J.
Published: July 2011

The area of psychological and physiological acoustics encompasses a wide and multidisciplinary range of topics. It is concerned with questions of what happens to sound once it enters the auditory system of humans and other species, and how sound is used to help organisms navigate their environment. Topics include the biomechanics of the middle and inner ear; the neuroscience of the auditory nerve, brainstem, and cortex; and behavioral and cognitive studies of auditory perception. This talk will give a brief overview of some of the many areas currently under investigation, ranging from basic questions about the neural codes used to represent aspects of sound to clinical applications, such as the development and improvement of cochlear, brainstem, and even midbrain implants that bypass the peripheral auditory system to restore hearing to people with profound hearing loss.
Introduction to Animal Bioacoustics.
Authors: Mellinger David K.
Published: July 2011

Animal bioacoustics (AB) covers all matters related to the production, transmission, and reception of sound in nature, as well as the investigation and use of natural sound by people and impacts of anthropogenic sounds by on animals. Topics include animal communication; sound production mechanisms; sound reception mechanisms (with P&P); evolution of sound production and hearing mechanisms; effects of acoustic propagation on natural sounds; sound detection, classification, localization and tracking; estimating populations and population density; impact of human-generated noise on animals; and a variety of other topics. All animals, and indeed all organisms, are considered within the scope of AB, though the most common taxa are marine mammals, birds, primates and other mammals, fishes, frogs and other amphibians, and insects.
An introduction to the technical committee on Noise.
Authors: Ryherd Erica E.
Published: July 2011

Noise is generally defined as “unwanted sound,” or more specifically sound that is “generally unpleasant,” or “interferes with one’s hearing of something,” or “lacks agreeable musical quality.” The demand for noise research and consulting continues to intensify in concert with rising population densities, increasingly industrialized societies, growing demands from consumers, and increasingly common standards and legislation related to noise. The Acoustical Society of America Technical Committee on Noise (TC Noise) is concerned with all aspects of noise, ranging from noise generation and propagation, to active and passive methods of controlling noise, to the effects of noise on humans and animals. Some specific interests include source mechanisms, predictions, measurements, evaluation, analysis, effects, regulation, mitigation, and legal aspects of noise.
The Musical Acoustics technical committee.
Authors: Morrison Andrew C.
Published: July 2011

The technical committee on musical acoustics (TCMU) is concerned with the application of science and technology to the field of music. Of particular current interest are topics which include the physics of musical sound production, music perception and cognition, and the analysis and synthesis of musical sounds and composition. The TCMU draws from a diverse body of scientists, engineers, musicians, instrument builders, psychologists, architects, and others interested in the study of the science of music. An overview of selected research topics and activities of the TCMU will be presented.
Structural Acoustics technical committee.
Authors: Capone Dean E.
Published: July 2011

An overview of the Structural Acoustics and Vibration Technical Committee (SAVTC) will be presented. The talk will provide a broad overview of the many research areas of interest to the SAVTC. In addition, a few topics will be explored in more depth to provide background on some of the more common analysis methods used by members of the technical committee. The content of the talk will be tailored to students and relative newcomers to the Acoustical Society of America.
Introduction to the Engineering Acoustics technical committee.
Authors: Warren Daniel M.
Published: July 2011

“Engineering acoustics encompasses the theory and practice of creating tools for investigating acoustical phenomena and applying knowledge of acoustics to practical utility”; thus opens the newly revised scope statement for the engineering acoustics TC, which was an occasion of some sole-searching in our group. The former scope had us pigeon-holed as “transducer guys.” While transduction is an important aspect of our field, this limited definition undermined the true role of engineering as an art common across and necessary for all other scientific endeavors. Behind every scientific discovery is a rack of test gear, and in front is a practical application of that discovery. This is what we do; we are the toolmakers, the designers, and the architects of acoustics.
An introduction to the Physical Acoustics technical committee’s activities.
Authors: Garrett Steven L.
Published: July 2011

The primary activity of any Technical Committee is to exploit the collective wisdom of the Committee’s membership to determine which research topics within its specialization area are most active and interesting. Based on that assessment, the Committee organizes special sessions at future meetings that will bring together experts from those areas, not necessarily limited to the Society members, who can share interesting results and provide guidance regarding the directions that will lead to further understanding. In Physical Acoustics, that is a particularly daunting challenge given the scope of topics that fall within its purview: use of sound to probe material properties, sound propagation and attenuation mechanisms on this planet and in other parts of the universe, and physical effects of sound and its interaction with other forms of radiation, all of which could also go well beyond the limitations of a linear acoustical theory. At just this meeting, PATC is sponsoring special sessions on gas hydrates and on violent cavitation. Needless to say, involvement in debates about “what is hot” is both interesting and valuable. Other activities include proposals for technical initiatives that allocate ASA resources. Recently, PATC received funding to sponsor a demonstration session at the Physical Acoustics Summer School.
Biomedical Acoustics: Making a quantum leap in medicine.
Authors: Porter Tyrone M.
Published: July 2011

At the dawn of a new era in medicine, the future of biomedical acoustics is bright. In the past century, we witnessed the introduction of ultrasound contrast agents, lithotripsy, and the visualization of ultrasound images in three dimensions. Currently, scientists are developing acoustic-based techniques for opening the blood-brain barrier transiently in order to treat brain tumors and neurological diseases. Additionally, researchers are developing echogenic liposomes and microbubbles for targeted ultrasound image enhancement and drug and gene delivery. Further excitement has been generated by the advances made with focused ultrasound to ablate or mechanically erode solid tumors in a noninvasive and site-specific manner. As technology and protocols continue to evolve, biomedical acoustics will have a dramatic impact on the diagnosis and treatment of debilitating diseases, thus improving patient care and quality of life.
Introduction to Acoustical Oceanography research and activities.
Authors: Siderius Martin
Published: July 2011

It could be argued that in many ways, we have a better understanding of the universe beyond earth than about the oceans right here. The difficulty in exploring the ocean might be put in perspective by recalling how long it took to find the Titanic after years of searching. Why is it so difficult to obtain information about the ocean? Consider the many tools we use in our terrestrial lives for exploration and convenience. These include GPS, mobile phones, remote sensing images (e.g., Google Earth), and wireless internet to name a few. Due to unfavorable propagation conditions for electromagnetics in the ocean, the equivalent tools mostly depend on acoustic signals. Therefore, exploring the ocean is highly dependent on using acoustic systems to do, for example, remote sensing, imaging, and communications. Acoustical oceanography is essentially concerned with the development and use of acoustical techniques to measure and understand the many parameters and processes of the sea. This presentation will provide an introduction to acoustical oceanography and describe some of the current research and activities. Topics include acoustic applications for ocean observing systems, remote sensing with ocean noise, acoustic techniques for studying marine life, and inverse methods for ocean and seabed properties.
Overview of Signal Processing in Acoustics.
Authors: Chambers David H.
Published: July 2011

Signal processing is used to some extent in all areas of acoustics such as extracting relevant information from acoustic measurements made either in the laboratory or in the field, processing signals, and/or synthesizing data to cope with demanding tasks raised in acoustics. Techniques range from simple classical approaches based on Fourier transforms and Gaussian noise to sophisticated model-based techniques that incorporate physical/parametric models of the acoustical system. In this talk we highlight new approaches to signal processing that could be applied to a broad variety of acoustical problems. Examples of each approach will be shown to illustrate the class of problems addressed and the performance. [This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.]
Community-based environmental noise management.
Authors: Finegold Lawrence S.
Published: July 2011

Many local noise control initiatives in the past have been very successful in engineering terms, but community noise problems still exist, more needs to be done, and without concerted and sustained action these problems will continue to get worse. However, deciding on the most effective noise control options for communities is not just a matter of promulgating legally required noise exposure criteria and/or mandating the development of action plans to achieve these required noise levels. There are often multiple, conflicting perspectives among the various stakeholders involved in the resolution of community noise issues, which must be resolved to achieve effective solutions. This presentation provides a brief introduction to some of the concepts and techniques that can be utilized to fill this need. It will introduce the idea of community-based environmental noise management, which includes a “tool-kit” concept, which can be used by local communities in developing effective, acceptable, and affordable noise policies. Major components of this approach include land use planning and urban design, the use of a modern environmental impact assessment Process (EIAP), implementation of state and local noise ordinances and building codes, plus related technical tools and various support requirements.
Application of vortex identification to acoustic streaming flows.
Authors: Sou Mei , Ray Chittaranjan , Layman Chris , Allen John S.
Published: July 2011

Acoustic streaming has an important role in a variety of industrial and medical ultrasound applications. Enhanced mixing and chemical processing can be achieved with the addition of ultrasound. Coherent structures in streaming flows, such as vortices, contribute to the overall transport and convective heat transfer. Their unsteady development is not well understood and thus the subject of on-going investigations. Previous studies measuring both acoustic heating and streaming have used thermocouples and been limited to specific spatial locations within the flow field. In this study, simultaneous velocity and temperature measurements are made using synchronized particle imaging velocimetry (PIV) and infrared thermography in a model sono-chemical reactor. This experimental system is water-filled acrylic tank with a 20 kHz Langevin acoustic horn mounted on the side. With overlapping fields of view for an IR camera and the PIV camera, the spatial-temporal evolution of the acoustic streaming and heating at the liquid surface is investigated. A vortex pair adjacent to the horn is identified with respect to its swirling strength and unsteady flow regimes are quantified in terms of the Lagrangian coherent structures (LCS) methodology. The swirling strength reveals the location of the vortex cores and LCS shows the evolving boundaries of the vortices.
Nonlinear scattering of crossed ultrasonic beams in a constricted flow for the detection of a simulated deep vein thrombosis.
Authors: Mock Sean M. , Korman Murray S.
Published: July 2011

A three phase experiment performed at the USNA Acoustics Laboratory uses turbulent flow to generate nonlinear scattering of crossed ultrasonic beams. The intent is to simulate blood flow through a vein with and without a constriction to flow and compare the nonlinear scattering effects. In phase 1, a submerged turbulent water jet (Re=4×104 and diameter=0.6 cm) interacts with overlapping crossed focused beams (f1=1.8 MHz, f2=2.0 MHz, and 15 cm focal lengths), 20 diam downstream, to create nonlinear scattering at the sum frequency (f+=f1+f2=3.8 MHz). A circular plane receiving transducer rotates azimuthally in the plane of the transmitted beam axes about the intersection to obtain angular dependent Doppler shift (about f+) and spectral broadening results. In phase 2, the turbulence at the meeting point is channeled into a simulated 30 cm long, 4.5 cm diameter “vein” with a thin, polyethylene membrane. Results show negligible nonlinearly scattered sum frequency, suggesting laminar flow. In phase 3, a constriction to flow is introduced via a 4.0 cm ping pong ball caught in a narrowed segment of vein. Results show a scattered sum frequency with narrow broadening, indicating the return of some vortices or turbulence.
On the axial drift of free pistons in acoustic systems.
Authors: Spoor Philip S.
Published: July 2011

Unlike the pistons in car engines, or other devices with crankshafts and other mechanical linkages, the pistons in acoustic devices such as pressure-wave generators, thermoacoustic coolers, or Stirling engines are part of a resonant system. The motion is induced by the overall dynamics of the system, but is not rigidly proscribed. It is therefore possible, and exceedingly common, for these pistons to experience axial “drift” from their nominal rest position while running. This most often occurs in devices that use radial “clearance seals” in which the working fluid flows in a very narrow annulus between the piston and the piston cylinder. There is no guarantee that the mass of fluid that “blows by” one way during one-half of the cycle equals the the mass that blows by during the second half; and in general these devices experience net mass transfer through the clearance seal, resulting in a buildup of dc pressure across the piston. This dc pressure tends to force the piston away from its natural center, shortening its useful stroke. Through our work with clearance seal devices, we have learned how to quantify the processes that cause this piston drift, and how to passively suppress it.
Enhancement of the photoacoustic effect and sonoluminescence in carbon suspensions through exothermic chemical reaction.
Authors: Park Han Jung , Diebold Gerald J.
Published: July 2011

Generation of the photoacoustic effect through chemical reaction of particulate carbon in chemically reactive solutions is presented. Experiments are carried out using a Q-switched Nd:YAG laser to heat carbon nanoparticles, initiating chemical reaction which results in sound production. The amplitude of the photoacoustic signal from a carbon suspension in H2O2–H2O mixtures is shown to increase dramatically as the percentage of H2O2 in solution increases. Laser induced chemical generation of sonoluminescence in aqueous carbon suspensions is also reported. Following irradiation and chemical reaction, highly compressed gas bubbles are formed. The expansion of the gas bubble past its equilibrium diameter results in oscillation of the bubble diameter. Tens of μs after the initial formation of the bubble, sonoluminescence is found to take place on collapse of the bubble. Experiments show that the sonoluminescent intensity is increased by a factor of more than 10 as the external pressure is increased from 1 to 6 atm. The time of appearance of optical radiation following the initial firing of the laser is found to decrease with increasing external pressure as well.
Looking back and hearing progress in the noise.
Authors: Rubel Edwin W.
Published: July 2011

The past 40 years we have witnessed an explosion of knowledge on the development and plasticity of the hearing organ, and the central pathways subserving hearing. Studies of the periphery have advanced from light microscopic descriptions of morphologic and cellular changes toward a detailed understanding of the molecular interactions responsible for cell specification and dynamic emergence of mature structures. Physiological studies evolved from measures of gross electrical potentials toward understanding the emergence of transduction events and the molecules controlling sensitivity and filtering of mechanics and electrical properties. Developmental analyzes of the central auditory pathways largely changed from descriptions of changing morphology and physiology that approach the mature phenotype toward the search for genetic and cellular interactions that underly such changes and there has been a growing interest in defining the developmental constraints on emergence of a mature structural and functional phenotype, the so-called plasticity of the system: real and potential therapeutic advances ranging from cochlear implants to hair cell regeneration and the potential for prevention of hearing loss of genetic and environmental origin. In this presentation I will try to wade through the noise and select some of the key areas of progress toward understanding the substrates of hearing development.
Effects of stimulus variability in auditory development.
Authors: Buss Emily , Leibold Lori J. , Grose John H. , Hall Joseph W.
Published: July 2011

Stimulus variability can affect the performance of child and adult listeners differently. For informational masking, stimulus variability appears to have a greater effect on children than adults in some conditions and a comparable effect in others. For intensity discrimination, children are less prone than adults to threshold elevation with the introduction of interval-by-interval stimulus level jitter. These results have been interpreted as reflecting different aspects of auditory processing. Informational masking in children is thought to reflect greater difficulty focusing on the signal cue. The intensity discrimination data have been interpreted as reflecting higher levels of internal noise and reduced sensitivity for intensity in children relative to adults. In the case of informational masking, supra-threshold masker variability may have a greater disruptive effect on signal processing, and in the case of intensity discrimination, variability near threshold has a smaller effect due to reduced sensitivity. Susceptibility to the disruptive effects of stimulus variability will be discussed as a means of gaining insight into the factors limiting auditory processing in children.
The time course of maturation on auditory tasks can differ between the average and consistency of performance and also between the sexes.
Authors: Huyck Julia J. , Wright Beverly A.
Published: July 2011

Between infancy and adulthood, performance on auditory perceptual tasks becomes both better on average and more consistent. However, little is known about the relationship between these two aspects of performance during development. This issue was investigated by using a cross-sectional design to estimate the ages at which measures of average performance (the mean of multiple threshold estimates for each listener) and performance consistency (the within-listener standard deviation of those estimates) became adultlike on two temporal-interval discrimination and four masking conditions (ages: 8–30 years, n=50–142 per condition). Average performance became mature before consistency on two simultaneous-masking conditions, after consistency on two nonsimultaneous masking conditions (backward and forward), and at the same time as consistency on the two temporal-interval discrimination conditions. In addition, on five of the six conditions, males matured more quickly than females on both measures or on consistency alone, but did not differ from females on either measure in childhood or adulthood. These results suggest that different processes may underlie the average and consistency of performance on auditory tasks and that transient sex differences in these processes could lead to a male advantage during adolescence on some of the everyday skills that rely on auditory perception. [Work supported by the NIH/NIDCD.]
A review of noise control methods for composite structures.
Authors: Mathur Gopal P.
Published: July 2011

Composite materials and structures offer great promise to all air vehicles and are being increasingly considered for lightweight advanced applications. However, composite structures are efficient radiators of noise mainly due to excitation and propagation of supersonic bending and/or shear waves in the structures. Composite skin-stringer structures mostly support supersonic flexural or bending waves propagating in the laminated structure whereas noise radiation by sandwich structures is dominated by supersonic shear waves in the core. The vibro-acoustic behavior of sandwich composites has been studied by several investigators. Wave number diagrams have been useful in identifying supersonic flexural and shear waves in composite structures. It has been shown that the radiating wave number components increase with increasing plate stiffness, causing increased sound radiation. Although design criteria for sandwich composites in terms of sub-sonic core wave speeds have been evolved, skin-stringer composite structures must use added noise control treatments. Noise control of composite structures, thus, still presents a significant technical challenge as the main advantages afforded by these structures, such as low weight and high strength, must not be compromised by added treatments. This paper presents a review of recent advances in the noise control techniques for composite structures.
On the study of wave propagation and the sound radiation of structures.
Authors: Chin Cliff
Published: July 2011

In this study, the wave propagation of structures in relation to the sound radiation and the sound transmission of structures are examined with analytical and numerical approaches. The 1-D structures (i.e., beams) demonstrate a simple example of how the wave propagation in sub- and supersonic regions affect the overall sound radiation of the beam. The same concept is extended to more complicated two-dimensional (2-D) structures such as metallic, composite, and sandwich panels, and the wavenumber spectral approach will be utilized to understand the sound radiation qualitatively. The wave speed may not be a sole factor in determining the final radiation efficiency of the structures, but it certainly helps engineers with designing light-weight, mechanically strong, and efficient sound insulator panels for aircraft vehicles.
Acoustical characteristics of honeycomb sandwich composite panels.
Authors: Kim Yong-Joe
Published: July 2011

For the purpose of investigating acoustical characteristics of various honeycomb sandwich composite panels, finite element method (FEM) combined with boundary element method (BEM) has been widely used. However, the latter approach is not always applicable to a relatively high-frequency analysis since it is required to use a large number of FEM/BEM meshes resulting in a high computational cost. In order to reduce computational resources as well as modeling times, a hybrid analytical/finite element method (HAFEM) is developed that uses a finite element approximation in thickness direction while analytical solutions are assumed in the directions parallel to a panel surface. By applying the HAFEM, three acoustical characteristics of honeycomb sandwich composite panels are identified: i.e., sound transmission characteristics, structural wave propagation characteristics, and sound radiation characteristics. By comparing measured sound transmission losses and predicted ones, the proposed HAFEM procedures are validated. It is shown that structural responses converge asymptotically to flexural waves in low-frequency region, core shear waves in mid-frequency region, and skin flexural waves in high-frequency region. It is also shown that the corner and edge radiation modes of finite size panels below critical frequencies can be visualized from predicted supersonic intensities.
Noise mitigation and wave number characterization in sandwich structures.
Authors: Sargianis James J. , Suhr Jonghwan
Published: July 2011

Sandwich structures are the ideal materials to use for many engineering applications since they are lightweight, strong, and stiff. While sandwich structures are mechanically advanced, their acoustic properties are not ideal since they are excellent sound radiators. Therefore by studying their wave number characteristics, the acoustic properties of sandwich structures can be improved to help mitigate noise propagation. This study used several different combinations of carbon fiber-epoxy, glass fiber-epoxy, and aluminum face sheets with honeycomb and Rohacell foam core materials. These beams were vibrated with an electro-dynamic shaker, while the vibration response was measured at numerous equidistant points along the beam with a micro-accelerometer. Results showed the frequency response functions, which were transformed to the wave number/frequency domain yielding dispersion plots. From this plot one can calculate the coincidence frequency of the sandwich structure, which determines how and when the structure will radiate noise. Experimental results showed that thin aluminum face sheets with Rohcell 51 WF foam core had the greatest noise mitigation properties with a coincidence frequency of approximately 4500 Hz. Furthermore, it is shown that the experimental wave speed values agree with analytical methods. [Work supported by The Boeing Company.]
Predicting response of a honeycomb sandwich panel to diffuse acoustic field vs turbulent boundary layer excitation using coupled finite element-boundary element approach.
Authors: Madjlesi Reza , Atalla Noureddine
Published: July 2011

Composite materials are being extensively used in primary and secondary aerospace structures due to high specific strength and stiffness as well as low weight. In this study finite element (FE) and boundary element (BE) are used to study acoustical performance of honeycomb type structures subjected to common excitation sources in flight. Coupled FE-BE is applied to predict transmission loss (TL) of honeycomb type structure, excited by diffuse acoustic field and turbulent boundary layer. Structural FE model correlation is performed using experimental modal analysis. Transmission loss of honeycomb panel was measured at the GAUS TL Lab using diffuse acoustic field. TL results are used to validate coupled FE-BE vibro-acoustic model of a curved honeycomb panel. Correlated model is used to predict response of structure to TBL source. Effect of noise control treatments in reducing radiated noise from honeycomb panel excited by TBL and diffuse field are studied.
Gradient perception of laryngeal contrast of stops in English and Korean: Eye-tracking evidence.
Authors: Kong Eun Jong , Edwards Jan
Published: July 2011

Categorical perception implies that listeners discard subphonemic acoustic variation and attend only to higher-level phonemic representations. However, a number of studies have shown that listeners are also sensitive to subphonemic fine phonetic detail, given the appropriate task. The current study aimed to investigate gradient perception of the stop voicing contrast using an anticipatory eye movement paradigm. Specifically, our study examined English- and Korean-speaking adults’ sensitivity to changes in VOT and f 0 parameters that differentiated their native stop voicing categories. The stimuli varied VOT values in six steps (9–59-ms) and f 0 in five steps (98–114 Hz) in synthesized CV syllables, with a vocalic source from either a male speaker of English or Korean. Adult listeners’ anticipatory eye movements to the target categories were collected, as they listened to a series of stimuli. Looking latencies were assessed in a mixed-effect regression model. Preliminary results found gradient responses to VOT changes for both English and Korean speakers as well as evidence of sensitivity to f 0 for Korean, but not English speakers. Results are also presented for bilingual English-Korean speakers, who were asked to perform the task in both English and Korean. [Work supported by NIDCD Grant No. 02932 and NSF Grant No. 0729140]
Production and perception of voice onset time cues in spoken Japanese and Taiwan Mandarin.
Authors: Ogasawara Naomi
Published: July 2011

This study investigates (1) VOT length of Japanese and Taiwan Mandarin (TM) stops in word-initial and word-medial positions of disyllabic words and (2) VOT boundary between voiceless and voiced stops in word-initial and word-medial positions of Japanese disyllabic words perceived by TM listeners. Japanese has voiceless and voiced distinction of stops, while Mandarin has aspirated and unaspirated distinction of stops. This discrepancy makes it hard for TM listeners to perceive Japanese stops correctly. In addition, based on my observation, stops in word-medial position seem to be more difficult for them to hear. In the first part of the study, an acoustic analysis is conducted to investigate the difference in VOT length of stops of the two languages. Perception experiments are conducted to examine the relationship between VOT boundary and the positions of stops in words. Groups of TM listeners at different Japanese proficiency levels participate in the experiments in order to test the effect of second language acquisition.
Assessing the relative importance of consonants and vowels in Spanish and English.
Authors: McAuliffe Michael E.
Published: July 2011

There appears to be a systematic difference in the dialectal variation of phonemes within languages. In his treatment of English dialects, Wells [(1982)] had three volumes detailing the vocalic differences of the dialects of English, but he remarked that these dialects “do not differ very greatly in their consonant systems” (1982:178). Conversely, Hualde [(2005)] detailed the dialectal variation of each consonant in detail, but only sad of vocalic variation that “vowel qualities are remarkably stable among Spanish dialects” (2005:128). These differences in variation suggest that English values consonants as more integral to a word, and Spanish values vowels more, as those are the more stable segments in their respective languages. To empirically test this observation, a lexical decision task [Goldinger (1996)] is employed, with native speakers of both English and Spanish, using nonwords varying from attested words either in a single consonant (such as ship versus shid in English) or a single vowel (such as ship versus shup). The predicted outcome is that languages that value consonants, such as English, will make the decision faster when the consonant is changed, and languages that value vowels, such as Spanish, will make the decision faster when the vowel is changed.
Perception of natural vowels by monolingual Canadian-English, Peninsular-Spanish, and Mexican-Spanish listeners.
Authors: Morrison Geoffrey Stewart
Published: July 2011

Based on a previously reported synthetic-vowel perception experiment, it was hypothesized that the location of the perceptual boundary between Spanish /i/ and /e/ differed for monolingual Peninsular-Spanish and Mexican-Spanish listeners (North-Central Spain and Mexico City), and this would affect the perception of the Canadian-English /i/—/ɪ/ contrast (Western Canada): Peninsular-Spanish listeners were predicted to identify almost all tokens of Canadian-English /i/ as Spanish /i/ and almost all tokens of Canadian-English /ɪ/ as Spanish /e/ (two-category assimilation), whereas Mexican-Spanish listeners were predicted to identify almost all tokens of Canadian-English /i/ as Spanish /i/, but identify some tokens of Canadian-English /ɪ/ as Spanish /i/ and some as Spanish /e/. Monolingual Peninsular-Spanish and Mexican-Spanish listeners’ perception of natural tokens of English /i/, /ɪ/, /e/, and /ε/ produced by monolingual Canadian-English speakers was tested. Both the Peninsular-Spanish and the Mexican-Spanish listeners had results consistent with the perceptual pattern predicted for the Peninsular-Spanish listeners. Implications for second-language speech perception are discussed.
Active change in American English dialects and their role in age perception.
Authors: Hadeed Krista , Harnsberger James
Published: July 2011

Prior studies on vocal aging have varied with respect to the perceptual relevance of vowel formants. Two patterns have been (inconsistently) observed: formant lowering due to age-induced laryngeal lowering and formant centralization. A third hypothesis was investigated here: that active changes in the vowel systems of American English dialects, lead by younger (especially female) speakers, can themselves serve as vocal age cues independent of the cited (physiological) changes. One active vowel change is the California vowel shift, involving the lowering/backing of [I], [E], and [ae], one that has also been observed in young speakers in Florida and elsewhere. Would such systematic differences in vowel quality occurring frequently in younger speech play a significant role in female voice age perception? Speech samples were collected from 20 young and 20 middle-aged female residents of northern Florida under four conditions: (a) while conversing with another speaker matched versus mismatched in age category and (b) having been trained (versus untrained) to accurately simulate the California vowel shift in younger speakers. Acoustic analysis and age estimation studies were conducted to determine if the presence of a natural/simulated “younger” dialect shifted perceived age and the extent of any shift relative formant lowering and formant centralization.
On the relationship between vocal aesthetics and speech perception.
Authors: McGuire Grant , Babel Molly , King Joseph , Miller Teresa , Satterwhite Alyssa
Published: July 2011

This study reports data from four experiments exploring the interplay of meta-linguistic analyzes and lower level tasks with the goal of understanding how judgments of vocal aesthetics and voice typicality affect voice and phoneme processing. In the first, speakers of west coast North American English rated the attractiveness of 60 American English voices. Results from this experiment were compared against the following ones. In the second experiment listeners were asked to rate the typicality of each voice for its sex. Ratings for both showed a strong correlation, suggesting that vocal attractiveness and voice typicality are related. In the next experiment listeners were asked to quickly classify the voices as male or female. Faster reaction times correlated with judgments of higher typicality, but not with attractiveness. Finally a group of listeners were asked to classify the vowels produced by the voices. Here a correlation was found with both rating tasks such that listeners were faster at vowel classification for both the more attractive voices and the more typical ones. Moreover, a correlation was found between both online tasks such that voices that listeners classified quickly by sex were also classified quickly by vowel.
The influence of concurrent working memory tasks on the visual contributions to speech.
Authors: Buchan J. N. , Munhall K. G.
Published: July 2011

Visual speech information can influence the perception of acoustic speech. In acoustically noisy environments, people can often understand more words correctly if they can see a talker as well as hear them. Additionally, conflicting visual speech information can influence the perception of acoustic speech (namely, the McGurk effect), causing a percept of a sound that was not present in actual acoustic speech. This auditory and visual speech information does not need to be perfectly synchronous in order to be integrated. Rather, there is a “synchrony window” over which this information can be integrated. The extent to which a distracting cognitive load task affects the influence of the visual speech is still not well understood. It is also unknown whether a distracting cognitive task has an influence on the integration of temporally asynchronous speech. A series of experiments using both speech-in-noise and McGurk tasks with concurrent working memory tasks was used to address this question. The temporal offset in some of the McGurk tasks was also manipulated. Overall, results suggest that while some interference of the cognitive task can be observed, this influence is quite small and does not have a substantial influence on the integration of asynchronous speech.
Sentence recognition in noise for English-, Chinese-, and Korean-native listeners.
Authors: Liu Chang , Jin Su-Hyun , Chen Chia-Tsen
Published: July 2011

The present study aims to investigate the effects of background noise on English sentence recognition for English-native (EN), Chinese-native (CN), and Korean-native (KN) listeners. The hearing in Noise Test (HINT) [Nilsson et al., (1994)] was used to measure the percent correct word identification in both quiet and noise conditions. Each sentence consists of uniform length with six syllables spoken by a female talker with general unaccented dialect-free American English. Two types of noise, multitalker babble and long-term speech shaped noise (LTSSN), were presented at various singal-to-noise ratios SNRs. Preliminary data demonstrated that first, the sentence recognition of non-native listeners was significantly lower than native listeners in both quiet and noise conditions; second, both native and non-native listeners showed significant amount of masking release at each SNR (−10, −5, and 0 dB SNRs); third, there was substantial individual variability in sentence recognition within each non-native group. This variability might be related with high variability in phoneme recognition in noise for the non-native individuals.
Identifying gender in fricatives: A comparison of human performance with a classification based on Cepstral coefficients.
Authors: Spinu Laura , Machnik Maica
Published: July 2011

A recent gender identification study using Cepstral coefficients extracted from voiced and voiceless fricatives from four different places of articulation yielded 78% correct classification in a linear discriminant analysis (LDA) [Spinu and Lilley (2010)]. This high accuracy was somewhat unexpected, as previous cross-linguistic studies of fricatives generally found no significant effects of gender on various types of acoustic measures. The current study investigates whether humans can identify gender based solely on frication noise as successfully as the LDA. 30 English-speaking undergraduates were asked to identify the gender of fricatives produced by 10 speakers (5 males and 5 females)—a subset of the sounds used in the LDA study. The analysis, currently in progress, suggests that humans may not be as successful as the LDA. These findings are expected to shed light on both (a) the differential distribution of acoustic features related to gender in fricatives, and (b) the extent to which these features are available/employed in human perception.
A technique for adjusting Gaussian mixture model weights that improves speaker identification performance in the presence of phonemic train/test mismatch.
Authors: McLaughlin Jack , Owsley Lane
Published: July 2011

Speaker identification is complicated by cases where training material is phonemically deficient. Misclassifications can result either because subsequent test material from that speaker contains primarily the phonemes missing from the training data or because that test material is phonemically most consistent with another talker’s model. This situation can arise in any dialog where, for reasons of brevity and clarity, conventions must be imposed on phraseology. We present here a technique for detecting phonemic deficiencies in a speaker model, and then correcting that model to partially compensate for the biased training data. This technique relies upon a specially constructed universal background model (UBM) from which speaker models are adapted. This UBM is formed by weighting several dozen phoneme GMMs using EM training. As a result, each Gaussian component of the UBM (and of the resulting speaker models) corresponds to a specific phoneme. Analysis of the speaker model weights reveals whether the training data had the typical phonemic variety found in ordinary speech, and if it did not, the weights are adjusted. Using a specially designed corpus created from the TIMIT utterances, we show that this reweighting technique improves performance over non-reweighted models. Results are also given for the Air Traffic Control Corpus.
Category interaction and stimulus effects in the perception of synthetic liquid+stop clusters.
Authors: Nearey Terrance M. , Tucker Benjamin V.
Published: July 2011

There are numerous studies of the perception of English stops in the syllables /arga, alga, arda, alda/ [e.g., A. Lotto and K. Kluender, Percept. Psychophys. 60, 602–619 (1998)]. Listeners give more /-da/ responses after /ar-/ syllables. There is controversy over the degree to which this effect involves general auditory contrast rather than phonetic context. The present study uses a two-dimensional continuum of 49 stimuli composed by crossing a seven-step /al-/ to /ar-/ series with a seven-step /-da/ to /-ga/ series. The variation in stimulus properties is localized to F3 only for both VC and CV stimuli. Listeners (n = 34) responded with all four categories. Results show clear phoneme level context effects. Ambiguous VC stimuli near the /al/-/arr/ boundary show significantly more /da/ responses in cases where the VC is heard as /ar/. This pattern is consistent with what has been called a diphone bias effect [T. Nearey, J. Acoust. Soc. Am. 101, 3241–3256 (1997)]. Surprisingly, for these stimuli, evidence for more continuous tuning of the /da/-/ga/ boundary by preceding l/r is quite weak. Thus, in this experiment, phonetic effects appear to dominate auditory contrast effects.
Why diverse spectral structure coheres for children.
Authors: Tarr Eric , Nittrouer Susan
Published: July 2011

Coherence masking protection (CMP) refers to the phenomenon in which lower thresholds for accurate vowel labeling are obtained when an informative F1 is presented with a constant, and therefore non-informative, F2/F3 cosignal than when F1 is alone. Tarr and Nittrouer reported this effect for adults and showed enhanced effects for children with synthetic speech [J. Acoust. Soc. Am. 126, S2300 (2009)]. With sine waves, no CMP was found for either group. Two new experiments asked what accounts for these differences across age and stimulus type. Hypotheses focused on the principle of common harmonic structure and expectations of speech-like signals. Experiment 1 combined sine-wave F1 with three synthetic cosignals, one that was harmonically related to F1 and two that were not. Experiment 2 used all synthetic speech, but F1 and the cosignal differed in harmonic structure. All signals were speech-like. Stimuli were presented in white noise for labeling, with and without the cosignal. Labeling thresholds were measured adaptively for F1 only and all three formants. Adults showed no significant CMP in either condition, but children did in both. It was concluded that children perceptually organize auditory signals based on the expectation of speech and do not require harmonicity. [NIDCD grant DC-00633.]