bluuebunny/crossref_metadata_2025 huggingface dataset:
Toward Safe Human Robot Collaboration by Using Multiple Kinects Based Real-Time Human Tracking
Authors: Morato Carlos , Kaipa Krishnanand N. , Zhao Boxuan , Gupta Satyandra K.
Published: October 2013

We present a multiple Kinects based exteroceptive sensing framework to achieve safe human-robot collaboration during assembly tasks. Our approach is mainly based on a real-time replication of the human and robot movements inside a physics-based simulation of the work cell. This enables the evaluation of the human-robot separation in a 3D Euclidean space, which can be used to generate safe motion goals for the robot. For this purpose, we develop an N-Kinect system to build an explicit model of the human and a roll-out strategy, in which we forward-simulate the robot's trajectory into the near future. Now, we use a precollision strategy that allows a human to operate in close proximity with the robot, while pausing the robot's motion whenever an imminent collision between the human model and any part of the robot is detected. Whereas most previous range based methods analyzed the physical separation based on depth data pertaining to 2D projections of robot and human, our approach evaluates the separation in a 3D space based on an explicit human model and a forward physical simulation of the robot. Real-time behavior (≈ 30 Hz) observed during experiments with a 5 DOF articulated robot and a human safely collaborating to perform an assembly task validate our approach.
Implementation of Trailer Steering Control on a Multi-Unit Vehicle at High Speeds
Authors: Roebuck Richard , Odhams Andrew , Tagesson Kristoffer , Cheng Caizhen , Cebon David
Published: October 2013

A high-speed path-following controller for long combination vehicles (LCVs) was designed and implemented on a test vehicle consisting of a rigid truck towing a dolly and a semitrailer. The vehicle was driven through a 3.5 m wide lane change maneuver at 80 km/h. The axles of the dolly and trailer were steered actively by electrically-controlled hydraulic actuators. Substantial performance benefits were recorded compared with the unsteered vehicle. For the best controller weightings, performance improvements relative to unsteered case were: lateral tracking error 75% reduction, rearward amplification (RA) of lateral acceleration 18% reduction, and RA of yaw rate 37% reduction. This represents a substantial improvement in stability margins. The system was found to work well in conjunction with the braking-based stability control system of the towing vehicle with no negative interaction effects being observed. In all cases, the stability control system and the steering system improved the yaw stability of the combination.
Contactless Shaft Torque Detection for Wide Range Performance Measurement of Exhaust Gas Turbocharger Turbines
Authors: Lüddecke Bernhardt , Filsinger Dietmar , Ehrhard Jan , Steinacher Bastian , Seene Christian , Bargende Michael
Published: October 2013

Turbochargers develop away from an auxiliary component—being “off the shelve”—towards an integrated component of the internal combustion engine. Hence, increased attention is paid to the accuracy of the measured turbine and compressor maps. Especially turbine efficiency measurement under engine-relevant operating conditions (pulsed flow) is recently receiving increased attention in the respective research community. Despite various turbine map extrapolation methods, sufficient accuracy of the input test data is indispensable. Accurate experimental data are necessary to achieve high quality extrapolation results, enabling a wide range and precise prediction of turbine behavior under unsteady flow conditions, determined by intermittent operation of the internal combustion engine. The present work describes the first application of a contactless shaft torque measurement technique—based on magnetostriction—to a small automotive turbocharger. The contactless torque measuring system is presented in detail and sensor principle as well as sensor calibration are illustrated. A sensitivity study regarding sensor position influences onto sensor signal proves the robustness and very good repeatability of the system. In the second part of the paper, steady state experimental results from operation on a conventional hot gas test stand over a wide map range are presented. These results are validated against full turbine stage (adiabatic as well as diabatic) CFD results as well as against “cold” efficiency measurements, based on measured inlet and outlet temperatures. The influence and relevance of bearing friction for such measurements is underlined and the improvements on this matter—achieved by direct torque measurement—are demonstrated.
Shape Optimized Heliostats Using a Tailored Stiffness Approach
Authors: Meng Li , You Zheng , Arif A. F. M. , Dubowsky Steven
Published: October 2013

In central receiver systems, the ideal reflective shape of a heliostat is a section of a paraboloid that adapting with the sun's angle and the mirror's location in the field. Deviation from this shape leads to optical astigmatism that increases the spot size on the receiver aperture, which eventually causes higher energy loss and lower conversion efficiency. However, it is challenging to implement the ideal shape by conventional design and manufacturing methods. In this paper, a novel compliant heliostat design methodology is proposed. By tailoring the two dimensional stiffness profile of a square plate, the paraboloid shape can be formed by a simple, low-cost mechanism with concentrated moment loads on the corners of the plate. The static optimized shapes, which can be easily realized by adjusting the loads according to the locations during heliostat assembly on the site, are suggested as approximations of the ideal shapes. Analytical models were developed in detail for the methodology. Numerical analysis consists of finite element analysis, optical ray tracing, and optimization. The numerical results illustrate that the performance of the shape optimized heliostats using tailored stiffness approach is close to the ideal shapes, providing substantial improvement in optical efficiency and reduction in spot size comparing to the flat mirrors. Furthermore, experiments on a prototype heliostat mechanism with a honeycomb-sandwich panel were conducted to validate the effectiveness of this low-cost shaping approach.
Finite Element Simulation of Process Control for Bolt Tightening in Joints With Nonparallel Contact
Authors: Ganeshmurthy Saravanan , Nassar Sayed A.
Published: October 2013

In this paper, 3D finite element analysis (FEA) is used to simulate and evaluate different process control methods that are commonly used for automating the assembly of bolted joints in a mass production environment. The finite element (FE) model takes into account the thread helix angle of a fastener along with parallel and nonparallel contact surfaces under the bolt head. Simulation includes the torque-only and the torque-turn process control methods for achieving a desired level of the bolt preload at initial assembly of the joint. The torque-only process control option is simulated by applying the target torque at which the tightening process is automatically stopped. On the other hand, a torque-turn or torque-angle method is simulated by first applying a low level (threshold) torque, to the bolt head, followed by turning the bolt head by a specified angle of turn in order to achieve the desired bolt tension. The effect of variables such as thread and underhead bearing friction coefficients and bolt hole clearance is investigated. The FEA simulation provided in this study would be helpful in developing a reliable tightening strategy for joints with nonparallel bearing surfaces.
Large Eddy Simulation of a Bluff-Body–Stabilized Flame With Close-Coupled Liquid Fuel Injection
Authors: Smith Andrew G. , Menon Suresh , Lovett Jeffery A. , Sen Baris A.
Published: October 2013

Large eddy simulations (LES) are performed of a bluff-body–stabilized flame with discrete liquid fuel injectors located just upstream of the bluff-body trailing edge in a so-called “close-coupled” configuration. Nonreacting and reacting simulations of the Georgia Tech single flameholder test rig [Cross et al., 2010, “Dynamics of Non-premixed Bluff Body-Stabilized Flames in Heated Air Flow,” Proceedings of ASME Turbo Expo, Paper No. GT2010-23059] are conducted using an Eulerian–Lagrangian approach with a finite volume solver. Experimental data is first used to characterize the boundary conditions under nonreacting conditions before simulating reacting test cases at two different fuel mass flow rates. The two fuel mass flow rates not only result in different global equivalence ratios but different spatial distributions of fuel, especially in the near-field wake of the bluff body. The differing spatial distribution of fuel results in two distinct flame dynamics; at the high-fuel flow rate, large-scale sinusoidal Bérnard/von-Kármán (BVK) oscillations are observed, whereas a symmetric flame is seen under the low-fuel flow rate condition.
A Critical Review of Passive Noise Control Techniques in Industrial Fans
Authors: Bianchi Stefano , Corsini Alessandro , Sheard A.G.
Published: October 2013

This review aims to assist engineers in understanding and applying passive solutions for reducing industrial fan noise. The paper systematically reviews the extant literature on passive noise techniques, with a particular focus on experimental rather than theoretical research. The review provides an assessment of the current state of the art in industrial fan flow and noise control. It offers a vision for potential improvements in noise reduction via novel application of flow and noise control technologies. The review examines the interaction between aerodynamic cause and acoustic effect and the application of control technologies that current cause and effect theories have inspired. The purpose is to provide a vision for aerodynamics research during the next decade that will serve as a basis for systematically reducing industrial fan noise emissions. The review provides an assessment of recent flow and noise control advances and considers some opportunities for future research. The review reflects an emphasis on low-speed industrial fans. The authors consider high-speed turbomachinery noise control, with the objective of illustrating the linkages between the two technologies. The review concludes with a summary of the opportunities for future research and its application to flow and noise control in industrial fan design.
Effect of Rate Sensitivity on Necking Behavior of a Laminated Tube Under Dynamic Loading
Authors: Shi Y. , Wu P. D. , Lloyd D. J. , Li D. Y.
Published: October 2013

An elastic-viscoplastic based finite element model has been developed to study the necking behavior of tube expansion for rate independent materials, rate dependent monolithic materials, and laminated materials during dynamic loading. A numerical study shows that for rate independent materials, the dynamic loading will not delay diffused necking but localized necking; for rate dependent materials, high strain rate sensitivity can significantly delay the onset of localized necking for both monolithic and laminated sheets and affect the multiple-neck formation in high-speed dynamic loading. The model also shows that a higher volume fraction of a clad layer with positive rate sensitivity material in a laminated sheet improves the sheet ductility.
Internal oxidation and mechanical properties of Ru based alloy coatings
Authors: Chen Yung-I , Chu Hsiu-Nuan , Chang Li-Chun , Lee Jyh-Wei
Published: October 2013

Ru based laminated coatings with various transition metal solutes were deposited on silicon wafers using a direct current magnetron cosputtering system. After annealing in a 1% O2–Ar atmosphere at 600 °C for 30 min, Ti–Ru, Zr–Ru, Mo–Ru, Hf–Ru, and W–Ru coatings were internally oxidized and maintained a laminated structure, consisting of alternating oxygen-rich and deficient layers stacked along the original growth direction. Conversely, V–Ru and Cr–Ru coatings exhibited external oxidation and failed to maintain the laminated structure after annealing, due to the fast outward diffusion of V and Cr. The variations in crystalline structure and nanohardness of Ru based coatings caused by oxidation after annealing were investigated.
The importance of the direct to reverberant ratio in the perception of distance, localization, clarity, and envelopment, Part one.
Authors: Griesinger David
Published: October 2013

The component of hall sound that travels directly from a musician to a listener carries information on both the location and distance of the sound source and is vital to both the clarity of the sound and the emotional involvement of listeners. Experiments in laboratories and a hall show that the human ability to separately perceive the direct sound in a reverberant field depends both on the time delay between the direct sound and the reverberant energy and on the direct-to-reverberant ratio (D/R). Threshold data for direct sound perception as a function of time delay and D/R will be presented, and their implications for listening room and hall design will be discussed. In large halls the delay can be long enough that the direct sound is perceptable at D/R values less than −10 dB, but in small halls the threshold becomes as high as 0 dB. Consequences for hall design include: early reflections in the best halls need not be lateral, small halls sound better with fewer early reflections (implying the use of non-shoebox shapes, absorbent stage houses, and shorter reverberation times), and in small halls electroacoustic enhancement should increase only the late reverberation.
Effects of room reverberation time and receiver position on measured binaural room impulse responses.
Authors: Ronsse Lauren M. , Wang Lily M.
Published: October 2013

This research examines the effects of room reverberation and receiver position on the fine detail in measured binaural room impulse responses, which can affect psychoacoustic perception in rooms such as speech segregation. Binaural room impulse responses have been gathered in four spaces with a range of shapes and reverberation times for three different receiver positions (center, 1 m from side wall, and 1 m from back wall) and three different source orientations (0, 45, and 90 deg from receiver). The directional loudspeaker is located approximately 0.5 m in front of the receiver for all conditions. Relationships between room reverberation times and measures impacting source localization such as interaural level differences and frequency-to-frequency fluctuations are analyzed. The results will determine if conclusions from previous research in this area conducted in a classroom [B.G. Shinn-Cunningham, N. Kopco, and T.J. Martin, J. Acoust. Soc. Am. 117, 3100–3115 (2005)] are applicable to spaces with varying shapes and reverberation times.
The impact of visual cues on perceived intimacy in an acoustic ecology.
Authors: Myrbeck Shane A. , Valente Daniel , Braasch Jonas , Gibbs Bobby
Published: October 2013

Crossmodal studies of the effects of visual cues on the perceived acoustics of a performance space have suggested the inextricable relationship between vision and audition. When designing a building or virtual environment for music, critical attention must be paid to a visual aesthetic to ensure a desired level of intimacy between the audience and performer. This visual aesthetic is ordinarily left entirely to the main architect or visual artist. However, given the body of research suggesting crossmodal influences on the human auditory system, it is clear that acousticians must also carefully consider the visual effects of their recommendations for acoustic improvement. The objective of this study is to establish the effects of various visual cues on audition as pertaining to intimacy in an ecological context. This study uses digital compositing (bluescreen) techniques to place a musical performance in various virtual environments, and employs real time audio-video processing to create an interactive, cross-modally immersive environment. Participant-adjusted direct-to-reverberant ratio as well as visual cues adapted from stage lighting techniques are used to establish crossmodal relationships. It is hypothesized that the ability to adjust visual cues will significantly effect subjects’ perception of intimate acoustic settings.
Stereotypy and variability in the mating call of the Lusitanian toadfish, Halobatrachus didactylus.
Authors: Amorim M. Clara P. , Simoes J. Miguel , Almada Vitor C. , Fonseca Paulo J.
Published: October 2013

During the breeding season, Lusitanian toadfish males become territorial and emit a tonal advertisement call (the boatwhistle) to attract mates to their nests. We recorded 16 males in the Tagus River estuary (Portugal) during the breeding season and studied boatwhistle variability in a short (minutes) and long time scale (days). We also related boatwhistle acoustic features with male physical characteristics. The recorded males were inside closed artificial nests in groups of eight individuals. Boatwhistles showed individuality in short periods of time but some males showed significant intraindividual variability in a longer time scale. Both social interactions (number of calling males) and tide level changed significantly male calling rate and acoustic characteristics of boatwhistles. The fundamental frequency of boatwhistles (equivalent to the sonic muscle contraction frequency) and boatwhistle emission rate were correlated with male condition (somatic and lipid content). Sound emission rate was also correlated with sonic muscle index. These results suggest that different toadfish males produce distinct boatwhistles, and that they have the ability to modulate the acoustic characteristics of their sounds with the level of social interactions, which increase during rising and high tide. Moreover, boatwhistles characteristics and acoustic activity seems dependent on male condition and sonic muscle index.
Toadfish boatwhistles also function as territorial keep-out signals.
Authors: Vasconcelos Raquel O. , Simoes J. Miguel , Fonseca Paulo J. , Amorim M. Clara P.
Published: October 2013

Boatwhistles produced by the toadfish Halobatrachus didactylus seem to function as mate attraction calls during the breeding season. Recent observations, however, indicate that their emission is not restricted to this period, suggesting that boatwhistles may have other functions. The possible dual function of boatwhistles was tested by eliciting sound production from reproductive males in advertisement and territorial defence contexts. These were simulated by creating aggregations of confined nesting males in an intertidal area and by conducting territorial intrusion experiments in tanks, respectively. Furthermore, we investigated whether parental care (eggs in the nest) affected the behavioral responses of territorial males. Nesting males kept in aggregations emitted boatwhistles spontaneously for several days. The relation between calling rate and number of eggs in the nest is under analysis. During territorial intrusions, resident males prevented the entrance of intruders in their shelters by producing mostly boatwhistles. Parental males revealed higher aggression levels, exhibiting additional threatening and attack behaviors. Agonistic boatwhistles differed from the mating calls by presenting less amplitude modulation and lower dominant and fundamental frequencies. These results suggest that, apart from attracting mates, the boatwhistles of batrachoidids may also function as an active keep-out signal during territorial defence.
Sound production and hearing in coral reef butterflyfishes.
Authors: Tricas Timothy C. , Boyle Kelly
Published: October 2013

Butterflyfishes (family Chaetodontidae) exhibit a diversity of close affiliative social behaviors. All 87 species of Chaetodon have a laterophysic connection and extensions of the anterior horns of the swim bladder near the otic capsule, which are proposed to impart sound pressure sensitivity to the normally mechanosensitive lateral line and acceleration-sensitive inner ear. Video kinematic analyses reveal that the motor action patterns used to produce pulsed sounds vary among species. The sound production mechanisms in Chaetodon and Forcipiger do not appear to be conserved, thus sound production may have evolved independently within the family. Species with long swim bladder horns have lower AEP hearing thresholds than those without, and deflation of the horns and bladder decreases hearing sensitivity in the former group. When the laterophysic connection and swim bladder horns are physically disrupted in wild fish, movement within their territories decreases and fish pairs swim closer together. Thus, the low intensity sounds produced by butterflyfishes may favor close social behaviors that increase communication efficiency among individuals on a noisy coral reef. We are currently investigating how hydrodynamic flow fields produced during social interactions may be used for intraspecific communication during these natural behaviors.
Assessment of cumulative sound exposure level as criterion for exposure of fish to impulsive sound.
Authors: Halvorsen Michele B. , Carlson Thomas , Popper Arthur N.
Published: October 2013

Acceptable exposure of fish to pile driving impulsive sound is currently determined by cumulative sound exposure level (SEL). The implicit assumption in this regulatory approach is that cumulative SEL, regardless of how reached, is one of the critical measures of sound exposure for fish health. We are testing this assumption by exposing juvenile Chinook salmon to sequences of impulsive sound differing in individual impulse SEL and number of impulses, but with the same cumulative SEL value. Test fish are exposed in a unique device that permits accurate simulative of impulsive pile driving sound. Following exposure, the hearing of test fish is evaluated using auditory evoked potential methods followed by necropsy for assessment of barotrauma. The null hypotheses we are testing is that the probability of hearing threshold shift ⩾6 dB and the probability of barotrauma mortal injury is the same for all cumulative SEL exposures. The results of these tests will determine the experimental design of additional tests to derive criteria for exposure of fish to pile driving sound. [Work supported by National Cooperative Highway Research Program (NCHRP) and Minerals Management Service (MMS).]
Spatial aspects of acoustic processing in complex environments.
Authors: Colburn H. Steven , Shinn-Cunningham Barbara , Sen Kamal
Published: October 2013

From the perspective of acoustical signal processing, it is a challenge to analyze a complex sound environment and segregate the acoustic mixture into individual sources, each with its own spatial characteristics and reverberation pattern. However, auditory systems perform this perceptually critical task with impressive ease. This talk will review how acoustical array processors work to separate sound sources. We then consider what most vertebrates, who have two point receivers separated in space, can accomplish by combining the signals that reach their two ears. The nature of the information available to bird and mammalian auditory systems is briefly reviewed, and the computational approaches these systems take to separating sound sources is assessed, including the logic of processing sound within narrow frequency channels over brief time epochs (rather than, e.g., undertaking broadband analysis). Some observations about the ability of classical binaural processing models to implement earlier stages of processing for these complex environments will be discussed. Finally, performance of human and zebra-finch subjects in tasks requiring judgments about individual sources embedded in complex sound mixtures will be considered in the context of physiologically motivated processing schemes. [Work supported by NIDCD: DC00100 (Colburn), DC05778 (Shinn-Cunningham), and DC07610 (Sen).]
Localization and identification of concurrent sounds in the owl’s auditory space map.
Authors: Keller Clifford H. , Takahashi Terry T.
Published: October 2013

In nature, sounds from multiple sources sum at the eardrums, generating complex cues for sound localization and identification. In this clutter, the auditory system must determine “what is where.” We examined this process in the auditory space map of the barn owl’s inferior colliculus using two spatially separated sources simultaneously emitting uncorrelated noises, which were uniquely identified by different frequencies of sinusoidal amplitude modulation. The neurons responded when either source was placed within the receptive field, suggesting two clearly segregated foci of activity at appropriate loci on the space map. The spike trains were locked strongly to the AM of the source within the receptive field, while the other source had minimal influence. Two sources AMed at the same rate were successfully resolved, suggesting that source separation is based on differences of fine structure. The spike rate and synchrony were stronger for whichever source had the stronger average binaural level. A computational model showed that neuronal activity was largely proportional to the degree of matching between the momentary binaural cues and the neuron’s preferred values. Individual neurons respond to and synchronize with sources in their receptive field if there are frequencies having an average binaural level-advantage over a second source. [NIH-DC003925.]
Some brain mechanisms for auditory scene analysis.
Authors: Middlebrooks John C. , Lee Chen-Chung , Macpherson Ewan A.
Published: October 2013

Detection and discrimination of sounds in complex auditory environments is facilitated by knowledge of the locations of sound sources and by spatial separation of signals and maskers. In studies of the spatial sensitivity of auditory cortical neurons in anesthetized cats, we find that location-dependent variation in temporal spike patterns can signal sound-source locations throughout up to 360 deg of space. In awake cats, spatial receptive fields can be similarly broad, although cortical neurons show a greater diversity of temporal patterns than is seen in anesthetized conditions. Our recent results demonstrate that spatial tuning tends to sharpen when a cat is engaged in an auditory task, compared to idle conditions, and that tuning can sharpen even further when the task involves sound localization. In human psychophysical studies, spatial hearing permits perceptual “stream segregation” of multiple temporally interleaved sequences of sounds. In parallel studies of the auditory cortex in anesthetized cats, we find that interleaved sound sequences, in configurations that likely would be segregated perceptually, result in activation of discrete cortical neuron populations. The spatial acuity for this neuronal stream segregation is substantially sharper than has been observed in studies of cortical representation of single sound sources.
On the use of broadband acoustic scattering techniques for observing physical and biological scattering features in the ocean.
Authors: Lavery Andone
Published: October 2013

Broadband acoustic scattering techniques, and associated signal processing techniques, are emerging as a powerful tool for the remote sensing of physical and biological scattering features in the ocean. These techniques allow (1) the frequency spectrum of oceanic scatterers to be measured, thereby resulting in enhanced classification and quantification potential relative to more traditional single-frequency scattering techniques, and (2) increased spatial resolution resulting in high-resolution images of oceanic scattering features, obtained through use of pulse compression signal processing techniques that exploit the broadband content of the signal. In this presentation, broadband processing techniques are discussed and results from laboratory and field measurements of broadband acoustic scattering from both physical and biological scatterers, spanning the frequency range from 100–600 kHz, are presented. Controlled laboratory broadband scattering measurements allow coherent ping-to-ping analysis to be performed as well as individual scattering features to be determined. The laboratory approaches are then expanded into the field to investigate physical and biological scattering features in the ocean on relevant temporal and spatial scales. Examples of broadband field measurements are presented from recent field experiments, and include scattering from nonlinear internal waves, zooplankton, turbulent oceanic microstructure, salinity microstructure in rivers, and bubbles.
Transverse coherence lengths, processing limits and implications.
Authors: Carey William M.
Published: October 2013

How does scattering in sound channels (deep and shallow waters) limit coherent array processing or what is the limitation of resolution in terms of the mutual coherence function and its temporal and spatial coherence lengths? The resolution of an array is limited by the mutual coherence function; but estimation in a partially coherent noise background with a multipath signal is difficult using the normalized cross power spectral density, magnitude squared coherence, because of the properties of both signals and noise. The measurement of magnitude-squared coherence is a poor statistical estimator since it is a function of the signal-to-noise ratio and multipath interference with large confidence bounds. Array gain measurements and a wave-theoretic coherence functional form can provide estimates of temporal and spatial coherence lengths defined as the 1/e value of this function. This paper reviews single path coherence results and those derived from array measurements over the low- to mid-frequency range in deep and shallow water. Representative coherence lengths are discussed in terms of boundary interactions, internal wave scattering, and coastal mesoscale features. The implications for arrays used to estimate geoacoustic properties, mammal locations, and scattering from the boundaries are presented.
Ceiling details in wood frame construction.
Authors: Keene James
Published: October 2013

In multifamily projects, the details of floor/ceiling installation have been a known and constant problem. Errors when installing noise control elements have caused lots of failures. Specifically, gypsum board ceiling and wall isolation with caulking is often short circuited when the gaps are incorrect. This paper details a new method of installing gypsum board ceilings and walls to provide a more easily inspected and detail assured isolation system. The system applies a similar system for ceiling installation as has become the standard in floor perimeter isolation. An “L” shaped fabric strip is installed around the perimeter of the room to create the gaps that today are created by the contractor in the field. The paper and presentation will review the methodolgy of the system and the laboratory test results that show performace compared to the present approach. The fire rated test performance will also be summarized. Since this is multifamily, the economic savings of this system are also presented.
Modeling sound transmission through large rectangular openings in a damped enclosure.
Authors: Xu Buye , Sommerfeldt Scott D.
Published: October 2013

The understanding of sound transmission through large rectangular openings in a damped enclosure plays an important role in designing noise reduction solutions where enclosures and openings are often involved. A complete solution for this problem should consider diffraction, coupling between exterior and interior sound fields, and damped boundaries, each of which is a challenging task. A theoretical model will be introduced in this paper that deals with all these phenomena and, in addition, also considers the effects of the direct sound field in the solution. Numerical simulations and experimental results will be presented and analyzed.
Three-dimensional mechanical tongue and vocal cord models for human speech production.
Authors: Fukui Kotaro , Shintaku Eiji , Ishikawa Yuma , Sakakibara Nana , Mukaeda Yoshikazu , Takanishi Atsuo , Honda Masaaki
Published: October 2013

We have developed talking robot Waseda Talker series, which mimicked human speech production mechanism. This robot is consisted of mechanical vocal cords, tongue, lips, and nasal cavity. The current version, WT-7R (Waseda Talker No. 7 Refined), has 16 DOF (7 DOF in tongue, 1 DOF in jaw, 4 DOF in lips, 1 DOF in velum, 2 DOF in vocal cords, and 1 DOF in lung), having same vocal tract length as average adult male. The mechanical vocal cord model is made of styrene based thermoplastic elastomer “Septon” and the shape is mimicking vocal folds of human with three dimensions. The vocal code model has pitch control mechanism by adjusting the cord tension and glottal opening-closing mechanism, and it could reproduce the vocal cord vibration of the vocal fry (double pitched) and the breathy voice (unclose in one cycle) as well as the modal voice with variable pitch. The three-dimensional tongue model is constructed by the rigid link mechanism covered by the Septon soft rubber. The tongue model could be controlled so as to configure the tongue shape in a three-dimensional way. We will describe the details of the mechanism of talking robot by showing some demonstration videos.
Biomimetic vocal tract modeling: Synthesis of speech articulation.
Authors: Hofe Robin , Moore Roger K.
Published: October 2013

In recent years, a number of researchers have started to investigate cognitive aspects of speech production using “speaking robots.” This paper introduces AnTon–the Animatronic Tongue and vocal tract model developed at the University of Sheffield, UK. AnTon’s distinctive feature is its design principle. Whereas other speaking robots are motivated by functionality—to produce a good imitation of human speech—AnTon mimics human anatomy, including tissue properties and muscle (actuator) configurations. Any ability to produce speech sounds emerges solely as a consequence from that anatomy. Such imitation of a biological system is called “biomimetic.” The reason to choose a biomimetic approach lies in the need for an experimental tool that makes speech articulation processes transparent. The use of realistic muscle configurations means that the model’s speech gestures can be mapped directly to human behavior, facilitating the evaluation of both the quality of AnTon’s speech gesture reproductions as well as any predictions about human behavior inferred from experiments with AnTon. AnTon will be used to clarify speech articulation processes, specifically in relation to energy efficiency of articulatory gestures and the importance of an auditory feedback loop. The project’s progress is continually documented on http://www.dcs.shef.ac.uk/∼robin/anton/anton.html.
Response of synthetic vocal fold models with geometry based on visible human project data.
Authors: Pickup Brian A. , Thomson Scott L.
Published: October 2013

Numerous synthetic and computational models have been and are currently being used in research studies of human vocal fold vibration. Model geometry plays an integral role in governing dynamic response. However, the various model geometry definitions have typically been idealized and often exhibit wide variability with each other. The present research compares the response of synthetic vocal fold models of different geometries. One model is based on idealized geometry, while the other is based on geometry obtained from the National Library of Medicine’s visible human project (VHP). The process for image extraction, model definition, and model fabrication is described, including: (1) image conversion from 2-D VHP image sequences to 3-D stereolithography (STL) format, (2) conversion to 3-D computer model format in which model geometric manipulations can be performed, and (3) fabrication of synthetic models using rapid prototyping. Results of measurements to characterize the dynamic response of self-oscillating synthetic vocal fold models, including onset and offset pressure, instantaneous glottal width using high-speed imaging, and glottal jet velocity profiles using particle image velocimetry (PIV), are presented for models based on both VHP data and idealized geometries. The sensitivity of the models to geometry changes is also reported.
Analysis of recent experimental studies of phonation threshold pressure done with a physical model of the vocal fold mucosa.
Authors: Fulcher Lewis P. , Scherer Ronald C. , Liu Chen , Nardone Marco
Published: October 2013

The pioneering work on the physics of small amplitude oscillations of the vocal folds by Titze resulted in a simple analytic formula that predicted the phonation threshold pressure of the uniform glottis to be a linear function of the glottal half-width, to be directly proportional to energy dissipation properties of the vocal fold, and to be reduced by the presence of a vocal tract. These relationships have been examined in a series of experiments [R. Chan and I. Titze, “Dependence of phonation threshold pressure on vocal tract acoustics and vocal fold tissue mechanics,” J. Acoust. Soc. Am. 119, 2351–2362 (2006)], and the linear connection with glottal half-width has been observed in several cases. However, the analysis described above did not consider the role of viscosity of the air, which may be important at small widths, as suggested by Lucero. The present study examines these experiments in the context of the surface wave model developed by Titze using intraglottal pressure distributions taken with the static physical model of the glottis M5. The M5 data include effects of viscosity and of flow separation. Preliminary results indicate that the threshold pressure should decrease as glottal width decreases, over the entire range of glottal widths examined by Chan and Titze. [Work supported by NIH R01DC03577.]
Vocal and postural coupling in singing and speech.
Authors: Vatikiotis-Bateson Eric , Oberg Martin , Barbosa Adriano , Hermiston Nancy , Kurth Richard
Published: October 2013

This study examines behavioral measures during speech and singing to assess the interaction of the postural control system and the production of expressive vocal behavior at different levels of vocal effort. We know that head motion is essential to both expressive speech and to balanced posture, suggesting that the head must be entrained to some extent by both subsystems simultaneously. This study shows that increased vocal effort (defined here as loudness) affects rigid body (6D) head motion and other measures of postural behavior acquired from force plates (6D) and video-based motion analysis (2D). Specifically, as vocalizations becomes louder, the postural system becomes more simply coupled spatially and temporally to the vocal system.
The influence of dynamic flow conditions on sound generation in fricative consonants.
Authors: Ramsay Gordon
Published: October 2013

Studies of speech production have often remarked that frication noise in voiced fricatives is weaker than that produced in homorganic voiceless fricatives. This is traditionally attributed to the reduction in mean flow (and, hence, Reynolds Number) produced by the glottal constriction needed to induce voicing. However, research in fluid mechanics has demonstrated that turbulence may develop quite differently in steady and unsteady background flows. Strong flow gradients may inhibit the transition to turbulence, or even relaminarize an already-developed turbulent flow. This paper describes a series of mechanical modelling experiments designed to investigate the effect of dynamic flow conditions on sound generation in fricatives. A feedback-regulated Kolvenbach flow valve, controlled by computer, is used to create carefully-shaped dynamic modulations of the air flow through a stereolithographic replica of the vocal tract, about a series of static flow conditions. A multitaper spectral analysis technique is then used in conjunction with sweeptone measurements to separate out the contribution of source and filter components to the far-field sound spectra recorded with a microphone, and source properties are compared across flow conditions. The observed variations cannot be explained by differences in mean flow alone, suggesting that dynamic effects may be important.
Transport theory for shallow water propagation with rough boundaries.
Authors: Thorsos Eric I. , Henyey Frank S. , Elam W. T. , Hefner T. Brian , Reynolds Stephen A. , Yang Jie
Published: October 2013

At frequencies of about 1 kHz and higher, forward scattering from a rough sea surface (and/or a rough bottom) can strongly affect shallow water propagation and reverberation. The need exists for a fast, yet accurate method for modeling such propagation where multiple forward scattering occurs. A transport theory method based on mode coupling will be described that yields the first and second moments of the field. This approach shows promise for accurately treating multiple forward scattering in one-way propagation. The method is presently formulated in two space dimensions, and Monte Carlo rough surface PE simulations are used for assessing the accuracy of transport theory results. [Work supported by ONR Ocean Acoustics.]
Parabolic equation modeling of anisotropic waves in heterogeneous media.
Authors: Metzler Adam M. , Siegmann William L. , Baer Ralph N. , Collins Michael D.
Published: October 2013

Wave propagation in heterogeneous media can be modeled efficiently with the parabolic equation method, which has been extended to problems with homogeneous anisotropic layers [A. J. Fredricks et al., Wave Motion 31, 139–146 (2000)]. This approach is currently being extended to the heterogeneous case, including piecewise continuous vertical dependence and horizontal dependence that is relatively gradual but which may be large over sufficient distances. Vertical dependence is included by applying appropriate heterogeneous depth operators in the equations of motion. Horizontal dependence is included by extending the single-scattering solution [E. T. Kusel et al., J. Acoust. Soc. Am. 121, 808–813 (2007)] to the anisotropic case. [Work supported by the Office of Naval Research.]
A comparison of acoustic uncertainty approximations in a Pekeris waveguide.
Authors: Dowling David R. , James Kevin R.
Published: October 2013

Uncertainty in environmental parameters is often the dominant source of error in underwater acoustic field predictions. This presentation provides comparisons of three techniques for assessing uncertainty in a predicted acoustic field caused by uncertainty in environmental parameters: field shifting, polynomial chaos expansion, and coarse uniformly sampled direct simulations. The uncertainty assessments are performed in a 100-m deep Pekeris waveguide with an uncertain water-column sound speed for frequencies of 100 Hz to 1 kHz at ranges of 1 to 10 km with a variety of common bottom types. The accuracy and computational efficiency of each approximation are quantified in terms of an absolute-difference error norm for the probability density function (PDF) of acoustic field amplitude and the number of acoustic field calculations necessary to predict this PDF, respectively. In all cases, the true field-amplitude PDF is determined from numerically converged direct numerical simulations. The strengths and limitations of each technique are highlighted and the applicability of these results to other sound channels and uncertain parameters is discussed. In particular, polynomial chaos expansion produces the highest accuracy but does so at the highest computational cost, while field shifting produces acceptable accuracy for the least computational cost. [Work sponsored by the Office of Naval Research.]
Modeling gradients in ocean acoustics.
Authors: Odom Robert I. , James Karsten
Published: October 2013

Modeling acoustic propagation in the ocean requires a representation of the ocean sound speed. For a 1-D, range independent ocean, probably the most common representation comprises constant sound speed layers and/or gradient layers. Gradients of the form 1/c2(z), admitting an exact solution for the acoustic pressure field in terms of Airy functions, are commonly employed. A disadvantage of using the Airy functions is that they are specific to that profile. For more general profiles, the best representation may be a stack of constant sound speed layers for which the pressure field is expressible in terms of simple exponentials. As an example, computing the backscattering strength from a stack of layers containing volume heterogeneities requires evaluation of an integral proportional to the 4th power of the pressure field. Integrating the simple exponential solutions for constant sound speed layers is trivial. Integrating a product of four Airy functions, either analytically or numerically, is not. If the medium is represented only by constant sound sound speed layers, what is the best way to choose the layers, and how many layers are needed? These questions are investigated by employing an algorithm originally due to Fuchs (1968). [Work partially supported by ONR.]
LEED (Leadership in Energy and Environmental Design) and indoor environmental quality—What about office acoustics?
Authors: Powell Kevin M.
Published: October 2013

Recent research conducted by the US General Services Administration and the Center for the Built Environment disclosed an anomaly about “green building” interiors, that is, an apparently unintended consequence of the current LEED rating system. The anomaly is this: while occupants of offices that have been upgraded to achieve LEED certification express high levels of satisfaction with the “indoor environmental quality” of these spaces on most dimensions, there is one exception where scores actually decrease. This exception is the only dimension where occupant DISsatisfaction grows—it is acoustics. What is it about LEED-rated offices that cause this anomaly to occur? Why are occupants dissatisfied with the “acoustical comfort” of the new LEED-certified offices? Is it because there are more reflective, hard surfaces causing noise to reverberate? Or because the HVAC system has become quieter? Or because partition heights have been lowered to allow better airflow and more natural light, resulting in less privacy? Since increased occupant dissatisfaction may result in reduced productivity or increased absenteeism, the GSA’s office of research has been examining this issue and will report on its findings and conclusions.
An acoustical consultant’s experiences with the leadership in energy and environmental design (LEED) green building rating system(s).
Authors: Salter Ethan
Published: October 2013

The panelist will discuss his experiences with several leadership in energy and environmental design (LEED) green building rating systems, developed by the U.S. Green Building Council (USGBC). He will provide insight into the process, advantages, and challenges of becoming a LEED accredited professional, his observations of how the promulgation of LEED acoustics credits will impact acoustics professionals, and also how the systems affect the solutions and products he recommends. The panelist became LEED accredited in 2006 and has consulted on several LEED projects across the country. He is active in his local chapter of the USGBC. Additionally, the panelist has attended the last four Greenbuild conferences put on by the USGBC.